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March 2023 Stormwater Management Plan - - 149 MAIN STREET
STORMWATER MANAGEMENT PLAN for Main and Second LLC 149 Main Street & 14 Second Street North Andover, Massachusetts Parcels 030-8-0 and 030-7-0 Prepared For: Main and Second, LLC c/o Crespo Group, LLC 65 Lewis Street East Boston, MA 02128 617.470.0339 Prepared By: Langan Engineering & Environmental Services, Inc. 100 Cambridge Street, Suite 1310 Boston, MA 02114 Hilary Holmes, P.E. hholmes@langan.com &OFN FRANK HELM ES CIVIL No.40203 u , 74, Frank Holmes, P.E. Massachusetts Licensed Professional Engineer No. 40203 fholmes@langan.com November 2022 Revised February and March 2023 A IVEiA IV Langan Project No. 151028501 00, Carnbridge Street, suite 1310 Boston, MA 02114 T 1 .824.9 o0 - 6 d82' �9 ° ° ,I a n gian com New,JerseyConnecticut*Massachusetts Pennsylvaniao,Wasfiirigton,,,DC lo 0hrioIllinoisFloridaArizona Colorado#Wasjhin California Atherris&Calgary a"Dubai*London*Panania TABLE OF CONTENTS Page No. EXECUTIVESUMMARY........................................................................................................... 1 1.0 INTRODUCTION............................................................................................................ 3 1.1 General .............................................................................................................. 3 1.2 Site Location ..................................................................................................... 3 1.3 Existing Conditions........................................................................................... 3 1.4 Project Description ........................................................................................... 4 1.5 FEMA ................................................................................................................. 4 1.6 Soil Conditions.................................................................................................. 4 2.0 STORMWATER MANAGEMENT.................................................................................. 5 2.1 Stormwater Management Regulations........................................................... 5 2.2 MassDEP Stormwater Performance Standards.............................................. 6 2.3 Design Criteria .................................................................................................. 9 2.4 Design Methodology.......................................................................................10 2.5 Existing Conditions Watersheds.....................................................................10 2.6 Proposed Conditions Watersheds ..................................................................11 3.0 STORMWATER QUALITY............................................................................................13 3.1 Stormwater Quality Improvements ...............................................................13 3.2 Additional Stormwater Quality Features.......................................................14 3.3 Retention and Infiltration Sizing.....................................................................14 4.0 STORM DRAINAGE COLLECTION SYSTEM DESIGN................................................15 4.1 Design Criteria .................................................................................................15 4.2 Design Methodology.......................................................................................15 4.3 Storm Drainage Collection Summary ............................................................16 5.0 CONSTRUCTION PERIOD POLLUTION PREVENTION AND EROSION AND SEDIMENTATION CONTROL PLAN............................................................................16 5.1 Introduction......................................................................................................16 5.2 Construction Sequence...................................................................................16 5.3 Construction Period Pollution Prevention Controls ......................................17 5.3.1 Perimeter Controls.............................................................................................17 5.3.2 Sediment Track-out Control ...............................................................................18 5.3.3 Stockpiled Soil or Sediment ...............................................................................18 5.3.4 Dust Control.......................................................................................................18 5.3.5 Minimize Disturbance of Steep Slopes ..............................................................18 5.3.6 Soil Compaction.................................................................................................18 5.3.7 Storm Drain Inlet Protection...............................................................................19 5.3.8 Dewatering ........................................................................................................19 5.3.9 Site Stabilization.................................................................................................19 TO C- 1 of 3 LAIVGA/V TABLE OF CONTENTS (Continued) 5.4 Pollution Prevention Standards......................................................................20 5.4.1 Spill Prevention and Response...........................................................................20 5.4.2 Designated Washout Areas ...............................................................................21 5.4.3 Proper Equipment, Vehicle Fueling, and Maintenance Practices........................21 5.4.4 Equipment and Vehicle Washing........................................................................21 5.4.5 Spill Control Equipment......................................................................................21 5.4.6 Spill Containment and Clean-Up Measures ........................................................21 5.4.7 Hazardous Materials Spill Report .......................................................................21 5.5 Operation and Maintenance of Erosion Control............................................22 5.6 Inspection Schedule ........................................................................................22 6.0 CONCLUSION ..............................................................................................................23 7.0 REFERENCES...............................................................................................................24 TO C- 2 of 3 LAIVGA/V TABLE OF CONTENTS (Continued) FIGURES Figure 1 Site Location Map Figure 2 FEMA Flood Hazard Map Figure 3 Aerial Map Figure 4 NRCS Hydrologic Soil Map DRAWINGS Drawing CS Series Site Plan and Details (Hard Copy Provided Under Separate Cover) Drawing CG Series Grading & Drainage Plan (Hard Copy Provided Under Separate Cover) Drawing CE Series Soil Erosion & Sediment Control Plan (Hard Copy Provided Under Separate Cover) Drawing LP Series Planting Plans and Details (Hard Copy Provided Under Separate Cover) Drawing EX-WS Existing Watershed Map (Appendix A) Drawing PR-WS Proposed Watershed Map (Appendix B) APPENDICES Appendix A Existing Stormwater Discharge Calculations Appendix B Proposed Stormwater Discharge Calculations Appendix C Stormwater Quality, Recharge, and Groundwater Mounding Calculations Appendix D TSS Removal Worksheets Appendix E Stormwater Collection System Calculations Appendix F Long Term Pollution Prevention Operation and Maintenance Plan Appendix G Illicit Discharge Compliance Statement Appendix H Geotechnical Test Pits & Borings TOC-3 of 3 LA/V&A/V Stormwater Management Report November 2022 149 Main Street& 14 Second Street North Andover, Massachusetts Langan Project No.: 151028501 EXECUTIVE SUMMARY The stormwater management report has been prepared in support of the proposed mixed-use development of an approximately 0.66-acre site comprised of two developed parcels at 149 Main Street and 14 Second Street in downtown North Andover, Massachusetts. The site is bound by Second Street to the north, Main Street to the east, and residential properties to the south and west. 149 Main Street is occupied by a one-story masonry building once used as a bank and a paved parking lot. 14 Second Street is occupied by a two-story wood framed residential home with a paved driveway. The existing buildings and paved areas will be demolished for the proposed development. The proposed development includes a three-story, mixed-use development with 6,700 square feet of commercial space on the ground floor and a total of 24 residential units on the second and third floors. The building with a ±14,800 sf footprint will occupy the north portion of the site with 22 at-grade tandem parking spaces covered by the building. The remaining portions of the site will be occupied by the driveway entrance on Main Street in the southeast corner of the site, the driveway exit on Second Street in the northwest corner, 22 surface parking spaces along the south and west sides of the site, and landscaping. A retaining wall up to approximately 5 feet in height will be required along the south side of the site in order to accommodate lower grades on the site and the higher grades along the neighboring properties. The predevelopment site impervious area is 0.570 acres (87% of the site) and the post-development site impervious area is approximately 0.595 acres (91 % of the site). The site is located in Zone X unshaded (areas outside of the 0.2% annual chance flood). Hydrologically, the site is located in the Merrimack River watershed. The Merrimack River is located approximately 2,225 feet to the northwest of site. The watershed is approximately 51010 square miles of which the project site encompasses a negligible area. The majority of the runoff from the site drains via overland flow to the catch basins and drain lines in Main Street and Second Street. The building at 149 Main Street appears to have roof leaders that connect underground directly to the 18-inch drain line in Main Street. In the proposed condition, the site will drain through closed pipe networks to stormwater treatment systems before discharging to the town drain lines in Main Street and Second Street. The existing hydrology of the site is being maintained to the maximum extent possible. The stormwater management report has been designed in accordance with the most recent versions of the town of North Andover Stormwater Management and Erosion Control Regulations, Massachusetts Department of Environmental Protection (MassDEP) Stormwater ES-1 of 2 A/VGA/V Stormwater Management Report November 2022 149 Main Street& 14 Second Street North Andover, Massachusetts Langan Project No.: 151028501 Handbook, and the U.S. Environmental Protection Agency's (EPA) National Pollutant Discharge Elimination System (NPDES) Small Municipal Separate Storm Sewer System (MS4) General Permit. It is the opinion of this office and the findings of this report that the proposed stormwater system, as designed, will effectively manage quality and quantity of stormwater runoff for the proposed development. ES-2 of 2 LA/V&A/V 1.0 INTRODUCTION 1.1 General The stormwater management report has been prepared in support of the proposed mixed-use development of an approximately 0.66-acre site comprised of two developed parcels at 149 Main Street and 14 Second Street in downtown North Andover, Massachusetts. The proposed development includes a three-story, mixed-use development with 6,700 square feet of commercial space on the ground floor and a total of 24 residential units on the second and third floors. The building with a ±14,800 sf footprint will occupy the north portion of the site with 22 at-grade tandem parking spaces covered by the building. The driveway entrance is proposed on Main Street in the southeast corner of the site and the driveway exit is proposed on Second Street in the northwest corner. There will be a surface parking lot with 22 spaces along the south and west sides of the site. The development includes site improvements including drainage, utilities, and landscaping. This report addresses the engineering design of stormwater conveyance and management systems for the project site. The predevelopment site impervious area is 0.570 acres (87% of the site) and the post-development site impervious area is approximately 0.595 acres (91 % of the site). 1.2 Site Location The project site consists of two adjacent parcels: a 0.59-acre parcel at 149 Main Street and a 0.07-acre parcel at 14 Second Street. The site is in the General Business (GB) and Downtown Overlay zoning districts. The two existing parcels that make up the project site will be combined and reconfigured into one lot. The site is bound by Second Street to the north, Main Street to the east, and residential properties to the south and west as shown on Figure 1 and 3. 1.3 Existing Conditions The site is currently developed. 149 Main Street is occupied by a one-story masonry building once used as a bank and a paved parking lot. 14 Second Street is occupied by a two-story wood framed residential home with a paved driveway. The existing buildings, paved areas, and existing improvements will be demolished for the proposed development. Site grades generally slope down from the high point (Elev. _ ±104) located in the southwest corner of the site to the low point (Elev. _ ±93) at the northeast corner of the site at the intersection of Main Street and Second Street. The existing finished floor elevation of the one-story masonry building is ±95 and the finished floor elevation of the residential home is ±102. Based on field LA/V&A/V observations Langan was able to determine the residential structure has a below grade level. Elevations reference the North Andover Vertical Datum. 1.4 Project Description The proposed development of the site includes a three-story, mixed-use development with 6,700 square feet of commercial space on the ground floor and a total of 24 residential units on the second and third floors. The proposed building has ±14,800 sf footprint. Site grades will be modified to accommodate the proposed development and a retaining wall with a maximum height of 5 feet will be required on the south side of the site in order accommodate lower grades on the site and the higher grades along the neighboring properties. An entrance drive on Main Street, an exit driveway on Second Street, parking, landscaping, site utilities, and stormwater management improvements are proposed to support the development. More information on the proposed watersheds can be found in Section 2.6 of this report. 1.5 FEMA According to the Flood Insurance Rate Map (FIRM) for Essex County published by the Federal Emergency Management Agency (FEMA), Map No. 25009CO209F effective 7/3/2012, the site is in Zone X. "areas determined to be outside the 0.2% floodplain (500 year floodplain).It See Figure 2 for the FEMA map. 1.6 Soil Conditions According to the USDA Natural Resources Conservation Service (NRCS)Web Soil Survey, the site soil type is comprised of Charlton fine sandy loam and Canton fine sandy loam (see Figure 4). The Web Soil Survey has classified these soils as hydrologic soil group B, see a description below. Group B: Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Langan performed a preliminary subsurface exploration throughout the site consisting of 3 borings (LB-01 through LB-03) and 4 test pits (TP-01 through TP-04) on 23, 24, and 25 May 2022. The borings and test pits were overseen by a Langan field engineer. Borings were advanced between 28 and 37 feet below the existing grades (about el. +59.0 to el. +72.0). The test pits were performed to depths ranging from about 2 to 7.5 feet below LAIVGA/V existing grades (about el. +89.5 to el. +99.0). The test pits were performed to observe soil conditions for the paved parking area as well as for storm water design. Soil profiles were visually examined and classified in the field in general accordance with the Unified Soil Classification System (USCS). Groundwater observation wells were installed in LB- 02(OW) and LB-03(OW). The bottom of the wells extend from about 28 to 30 feet below existing grades (about el. +59.0 to el. +64.5). The subsurface conditions generally consist of a surficial layer of asphalt underlain by layers of fill and till. Below the surficial material an about one to three foot thick layer of fill was encountered in all borings and test pits. Two distinct layers of fill where encountered during our investigation. Immediately below the pavement a one foot thick layer of fill consisting of an orange-brown fine to medium sand with varying amounts of silt and gravel was encountered in all borings and test pits, except for LB-02. Below this layer of fill, and below the pavement in LB-02, a one to two foot thick layer of fill consisting of a brown to gray fine to medium sand with varying amounts silt, fine to coarse gravel, glass, wood, bricks, and asphalt was encountered in all borings and test pits except LB- 01 and TP-01. Below the fill a layer of glacial till was encountered in all borings and test pits up to about 37 feet below ground surface (about el. +59). The glacial till is generally composed of silty fine to medium sand with varying amounts of silt, clay, gravel, cobbles, and boulders Groundwater was first encountered in the borings from about 4 to 6.5 feet below existing grade (about el. +88.5 to el. +92.0). Groundwater was observed to stabilize in the observation wells from about 5 to 6 feet below existing grade (about el. +89.0 to el. +95.0). An exploration location plan, boring logs, and test pit logs are provided in Appendix H. 2.0 STORMWATER MANAGEMENT 2.1 Stormwater Management Regulations The purpose of the Stormwater Management Plan is to provide long-term protection of natural resources in and around the site. This is achieved by implementing stormwater quality and quantity control measures designed to reduce pollutant discharge from the site, maintain a level of stormwater recharge, and control discharge rates. The following regulations and guidelines where referenced for this project: • Massachusetts Stormwater Handbook (2008) LA/V&A/V • U.S. Environmental Protection Agency (EPA) National Pollutant Discharge Elimination System (NPDES) Stormwater Permit for Construction Activities (EPA, Federal Register, December 8, 1999 as amended). • Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas, Department of Environmental Protection, Bureau of Resource Protection (May 2003) • U.S. EPA's NPDES Small Municipal Separate Storm Sewer Systems (MS4) General Permit (EPA, 2016). • Massachusetts Department of Transportation Project Development and Design Guide, Chapter 8 Drainage and Erosion Control (2006) • Town of North Andover Stormwater Management and Erosion and Control Regulations (2022) 2.2 MassDEP Stormwater Performance Standards A summary of MassDEP Stormwater Performance Standards as well as a method of ensuring compliance with each standard are summarized below: 1. No new stormwater conveyances may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. Response: Stormwater will be treated on site with a combination of street sweeping,trench drains,water quality units, and a subsurface infiltration and detention system and will connect to the town drain lines. 2. Stormwater management systems shall be designed so that post-development peak discharge rates do not exceed pre-development peak discharge rates. This Standard may be waived for discharges to land subject to coastal storm flowage as defined in 310 CM R 10.04. Response: The development of this site, as discussed in Section 2.5 and 2.6 and Appendix A and B of this report,will result in an overall decrease of peak discharge rates from the existing condition. 3. Loss of annual recharge to groundwater shall be eliminated or minimized through the use of infiltration measures including environmentally sensitive site design, low impact development techniques, stormwater best management practices, and good operation and maintenance. At a minimum, the annual recharge from the post-development site shall approximate the annual recharge from pre-development conditions based on soil type. This Standard is met LAIVGA/V when the stormwater management system is designed to infiltrate the required recharge volume as determined in accordance with the Massachusetts Stormwater Handbook. Response: This project proposes a subsurface infiltration and detention system to promote groundwater recharge. Supporting calculations regarding groundwater recharge volume can be found in Section 3.3 and Appendix C of this report. 4. Stormwater management systems shall be designed to remove 80% of the average annual post-construction load of Total Suspended Solids (TSS). This Standard is met when: • Suitable practices for source control and pollution prevention are identified in a long- term pollution prevention plan, and thereafter are implemented and maintained; • Structural stormwater best management practices are sized to capture the required water quality volume determined in accordance with the Massachusetts Stormwater Handbook; and • Pretreatment is provided in accordance with the Massachusetts Stormwater Handbook. Response: Runoff generated from the proposed project will meet the water quality requirements of this standard using a variety of on-site treatment practices to exceed the 80% TSS removal requirement. Proposed treatment train features include trench drains with filters,water quality units, and a subsurface infiltration system. The TSS Removal Worksheets can be found in Appendix D of this report. Stormwater Operations & Maintenance Measures are included in Appendix F of this report. 5. For land uses with higher potential pollutant loads, source control and pollution prevention shall be implemented in accordance with the Massachusetts Stormwater Handbook to eliminate or reduce the discharge of stormwater runoff from such land uses to the maximum extent practicable. If through source control and/or pollution prevention all land uses with higher potential pollutant loads cannot be completely protected from exposure to rain, snow, snow melt, and stormwater runoff, the proponent shall use the specific structural stormwater BMPs determined by the Department to be suitable for LAIVGA/V such uses as provided in the Massachusetts Stormwater Handbook. Stormwater discharges from land uses with higher potential pollutant loads shall also comply with the requirements of the Massachusetts Clean Waters Act, M.G.L. c. 21, §§ 26-53 and the regulations promulgated thereunder at 314 CMR3.00, 314CMR4.00and314CMR 5.00. Response: The site is not considered a high pollutant load generator. The Water Quality Volume (WQV)for the redevelopment will treat 0.5- inch of rainfall over all new impervious surfaces with the exception of the roof areas. 6. Stormwater discharges within the Zone II or Interim Wellhead Protection Area of a public water supply and stormwater discharges near or to any other critical area require the use of the specific source control and pollution prevention measures and the specific structural stormwater best management practices determined by the Department to be suitable for managing discharges to such areas as provided in the Massachusetts Stormwater Handbook. A discharge is near a critical area, if there is a strong likelihood of a significant impact occurring to said area, taking into account site-specific factors. Stormwater discharges to Outstanding Resource Waters and Special Resource Waters shall be removed and set back from the receiving water or wetland and receive the highest and best practical method of treatment. A "storm water discharge" as defined in 314 CM R 3.04(2)(a)1 or (b) to an Outstanding Resource Water or Special Resource Water shall comply with 314 CM R 3.00 and 314 CM R 4.00. Stormwater discharges to a Zone I or Zone A are prohibited unless essential to the operation of a public water supply. Response: Proposed stormwater management system discharges are not within the Zone II or Interim Wellhead Protection Area of a public water supply and are not near or to any other critical area. Water quality treatment will be provided based on a prescribed water quality treatment volume in accordance with the MassDEP policy. 7. A redevelopment project is required to meet the following Stormwater Management Standards only to the maximum extent practicable: Standard 2, Standard 3, and the pretreatment and structural best management practice requirements of Standards 4, 51 and 6. Existing stormwater discharges shall comply with Standard 1 only to the maximum extent practicable. A redevelopment project shall also comply with all other requirements of the Stormwater Management Standards and improve existing conditions. LAIVGA/V Response: The site is not considered a redevelopment. The project will fully meet all of the requirements of the MassDEP Stormwater Standards. 8. A plan to control construction related impacts including erosion, sedimentation and other pollutant sources during construction and land disturbance activities (construction period erosion, sedimentation, and pollution prevention plan) shall be developed and implemented. All redevelopment projects shall fully comply with Standard 8. Response: Soil erosion and sediment control plan has been developed for this project and can be found in the drawings attached to this report. The plan has been designed in accordance with the Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas. 9. A long-term operation and maintenance plan shall be developed and implemented to ensure that stormwater management systems function as designed. Response: Stormwater Operations & Maintenance Plan is included in Appendix F. 10. All illicit discharges to the stormwater management system are prohibited. Response: The stormwater management system for this site does not include any illicit connections to the stormwater system. An illicit discharge compliance statement is included in Appendix G of this report. 2.3 Design Criteria Peak flow rates at all points of discharge from the site were analyzed to compare proposed discharge rates with the existing condition. The storms analyzed include the following: • A 2-year, 24-hour storm consisting of 3.14 inches of rainfall • A 10-year, 24-hour storm consisting of 4.98 inches of rainfall • A 25-year, 24-hour storm consisting of 6.13 inches of rainfall • A 100-year, 24-hour storm consisting of 8.80 inches of rainfall These events are based on the most current data and the greatest depth of rainfall from National Oceanic and Atmospheric Administration (NOAA) Precipitation Frequency Data LAIVGA/V Server (PFDS) and the Northeast Regional Climate Center (NRCC) Atlas of Precipitation Extremes for the Northeastern United States and Southeastern Canada. 2.4 Design Methodology The peak runoff discharges for the existing and proposed conditions were analyzed using Soil Conservation Service (SCS) methodology, which outlines procedures for calculating peak rates of runoff resulting from precipitation events, and procedures for developing runoff hydrographs. Values for area, curve number, and time of concentration were calculated for the existing and proposed conditions. The curve number "CN" is a land-sensitive coefficient that dictates the relationship between total rainfall depth and direct storm runoff. The soils within the watershed are divided into hydrologic soil groups (A, B, C and D) as previously described. The time of concentration, Tc, is defined as the time for runoff to travel from the hydraulically most distant point in the watershed to a point of interest. Values of time of concentration were determined for existing and proposed conditions based on land cover and slope of the flow path, using methods outlined in the SCS methodology. For this study, a 24-hour SCS Type III standard rainfall distribution was used to determine the peak flow rate to all points of discharge from the site. 2.5 Existing Conditions Watersheds The site has been broken into two watersheds, with corresponding design points, as shown on the EX-WS map included in the drawings attached to this report. The existing watersheds analyzed in this report were delineated into Watershed A and B as described below: Watershed A. ±0.183 acres, includes the portion of the site that sheet flows towards the east property line to catch basins and to the 18-inch drain line in Main Street and the building roof leaders that are connected to the 18-inch drain line (Design Point A). This watershed consists of the masonry building, paved parking lot, and a narrow vegetated open space along the south border of the property line. Watershed A-0, ±0.030 acres, includes the portion of the offsite adjacent property that flows from the roof down spouts and sheet flows onto the site parking lot and towards the east property line to catch basins and to the 18-inch drain line in Main Street (Design Point A). This watershed consists of a section of the existing abutting building's rooftop located at 159 Main Street. LAIVGA/V Watershed B. ±0.473 acres, includes the portion of the site that sheet flows towards the north property line to the catch basins and to the 12-inch drain line in Second Street (Design Point B). This watershed consists of the house with surrounding vegetated open space, paved parking lot, and a narrow vegetated open space along the west and south border of the property line. Watershed B-0, ±0.007 acres, includes the portion of the offsite adjacent property that sheet flows onto the site and towards the north property line to the catch basins and to the 12-inch drain line in Second Street (Design Point B). This watershed consists of a section of the impervious paved lot and shed rooftop located at 161 Main Street along the south border of the property line. 2.6 Proposed Conditions Watersheds The extent of the proposed watersheds is within the previously defined limits of the existing watersheds. The watersheds have been delineated to model the proposed conditions, as shown on the PR-WS map included in the drawings attached to this report. The proposed watersheds are A-1, A-21 B-1, B-21 B-3, and B-4. Watershed A-1, ±0.011 acres, includes small area in the front of the building that sheet flows into Main Street (Design Point A). The watershed will consist of landscaped areas and impervious sidewalk. Watershed A-2, ±0.165 acres, includes the entrance driveway, a portion of the parking lot, and landscaped area. Runoff from this area will be captured by a trench drain and conveyed to a water quality unit and discharge to the 18-inch drain line in Main Street (Design Point A). This watershed consists of impervious driveway and parking lot and landscaped areas. Watershed A-0, ±0.037 acres, includes a portion of the offsite adjacent properties that sheet flows onto the site parking lot. Runoff from this area will be captured by a trench drain and conveyed to a water quality unit and discharge to the 18-inch drain line in Main Street (Design Point A). This watershed consists of a section of the house rooftop located at 159 Main Street and a portion of the shed rooftop and impervious paved lot located at 161 Main Street.Watershed B-1, ±0.340 acres, includes the building. Runoff from this area will be captured by roof drains and conveyed to the subsurface infiltration and detention system. By means of an outlet control structure, attenuated flows are then LAIVGA/V discharged to the 12-inch drain line in Second Street (Design Point B). The watershed will consist of impervious building. Watershed B-2, ±0.056 acres, includes the southwest portion of the parking area and a landscaped area that will be captured by a trench drain with a filter for pretreatment and conveyed to the subsurface infiltration and detention system. By means of an outlet control structure, attenuated flows are then discharged to the 12-inch drain line in Second Street (Design Point B). Watershed B-3, ±0.063 acres, includes the northwest portion of the parking area, the exit driveway, and landscaped areas that will be captured by a trench drain and conveyed to a water quality unit and discharge to the 12-inch drain line in Second Street. (Design Point B). Watershed B-4, ±0.020 acres, includes a small area in front of the building that sheet flows into Second Street (Design Point B). The watershed will consist of landscaped areas and impervious sidewalk. Refer to Table 1 for a comparison of pre-construction and post-construction peak flow rates and volumes at each design point. Refer to Appendix A and B of the Stormwater Report for the HydroCAD analysis. As stated previously in this report, the project has been designed so that post- construction peak flow rates do not exceed pre-construction peak flow rates, as required by MassDEP Stormwater Standard 2. There is an increase in runoff volume in the post- construction condition when compared to the pre-construction condition at Design Point A for the 10-, 25-, and 100-year storm events and at Design Point B for the 100-year storm event. The project is not required to mitigate for the volume of runoff increase, however it is a small 1-4% increase and is not anticipated to cause downstream runoff issues. LAIVGA/V Table 1: Peak Flow Runoff Rate and Volume Comparison, Existing vs. Proposed Conditions Design Point Condition 2-year 10-year 25-year 100-year Peak Flow Rate Pre(cfs) 0.57 0.93 1.16 1.69 Post(cfs) 0.53 0.91 1.14 1.67 Delta -0.04 -0.02 -0.02 -0.02 A Volume Pre(cf) 1,917 31223 4,051 5,924 Post(cf) 1,873 31267 41138 61186 Delta -44 44 87 262 Peak Flow Rate Pre(cfs) 1.23 2.11 2.66 3.92 Post(cfs) 1.21 2.04 2.56 3.77 Delta -0.02 -0.07 -0.10 -0.15 6 Volume Pre(cf) 3,790 61708 8,581 12,850 Post(cf) 3,398 61534 8,494 13,112 Delta -392 -174 -87 262 3.0 STORMWATER QUALITY 3.1 Stormwater Quality Improvements The stormwater management system has been designed in accordance with the MassDEP Stormwater Handbook, the Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas, the town of North Andover Regulations, and to the greatest extent practicable the Massachusetts Small MS4 General Permit. The WQV has been calculated using 0-5-inch over all new impervious areas, with the exception of roof areas. Groundwater recharge volumes have also been addressed for the site. Required volumes were calculated for each watershed based on the MA Stormwater Handbook guidelines. The calculation work sheets for water quality volume can be found in Appendix C. The site utilizes a number of stormwater features to provide stormwater quality and attenuation. Below are the features used in the proposed design: LA/V&A/V • Underground Infiltration/Detention Systems: Provides attenuation of peak runoff rates before discharging downstream. • Proprietary Separators (Water Quality Units): Provides TSS removal and oil water separation. • Proprietary Trench Drain Filters: Trench drain on the site that discharge to the infiltration/detention system will have filters installed to provide pretreatment. The measures described above were designed to remove 80% of the average annual load of TSS generated from the total post-construction impervious surface area on the site as required by the town of North Andover Stormwater Regulations and the MassDEP Standard 4: Water Quality. The TSS Removal Worksheets can be found in Appendix D of this report. 3.2 Additional Stormwater Quality Features In addition to the water quality improvements described above, the following water- quality control measures will be provided: • Operations & Maintenance Plan: Comprehensive Operations and Maintenance programs have been developed for the proposed site. These programs include regular pavement sweeping, and trench drain cleaning. Refer to Appendix F. 3.3 Retention and Infiltration Sizing The underground infiltration system has been designed in accordance with Volume 3 Chapter 1 of the Massachusetts Stormwater Manual. This system meets and surpasses the required volume and recharge rate as noted in the calculations below. A field investigation was performed to confirm soil texture and depth to groundwater and bedrock. See Appendix H. Recharge volume and minimum sizing criteria for the infiltration system has assumed an infiltration rate based on the hydrologic soil group B and soil classification of sandy loam. The Rawls Rate used was 1.02 in/hr. See Appendix C for recharge volume calculations. Total Required Recharge Volume (Rv) for the Project Rv = Required Recharge Volume F = Target Depth Factor associated with Hydrologic Soil Group (HSG) Alm,,= Total Impervious cover associated with LAIVGA/V Rv = I(F) x (Almp) Rv = 1,155 cubic feet Refer to Appendix C for detailed Rv calculations. Total Provided Recharge Volume for the Project = 1,268 cubic feet Drawdown Time . Rv Timedrawdown = (K)(Bottom Area) = # hr < 72hr Rv = Design Storage Volume K = Rawls rate per HSG Subsurface infiltration and detention system drawdown time is 8 hours. Refer to Appendix C for 72-hour Drawdown Analysis calculations. The underground infiltration and detention system has been sized for the 100-year design storm. 4.0 STORM DRAINAGE COLLECTION SYSTEM DESIGN 4.1 Design Criteria The proposed subsurface storm drainage collection system is designed to convey the 25-year design storm event to the discharge locations. 4.2 Design Methodology The storm drainage system was analyzed using the Rational Method for estimating runoff for a 25-year design storm event. The site was divided into subareas, each contributing runoff to an individual catch basin, inlet or roof drain. A value for area, time of concentration, and runoff coefficient was calculated for each contributing subarea. See Appendix E. Values of time of concentration were chosen based on land cover and flow path slope from the hydraulically most distant point in the subarea to the appropriate inlet. A minimum six-minute inlet time was assumed for each subarea. The average runoff coefficient, is the weighted average of the land uses within the drainage area. The runoff coefficient is an empirical coefficient representing the ratio of LA/V&A/V runoff to the rate of rainfall. The following runoff coefficients were used when calculating the average runoff coefficient for each drainage area. CONDITION C Grass/Landscaping 0.30 Paved/Impervious 0.90 Rainfall intensities were taken from the intensity-duration-frequency curve for Massachusetts as presented in National Weather Service (NOAA) Precipitation Frequency Data Server (PFDS). Storm drainage pipes were then sized based on calculated flows using Manning's Equation and were verified by solving for the hydraulic grade line. 4.3 Storm Drainage Collection Summary The runoff from the development will be collected using a conventional roof drains, trench drains, and manhole system. In cases of large storm events where overtopping occurs along the collection system, all flooding is directed away from buildings. 5.0 CONSTRUCTION PERIOD POLLUTION PREVENTION AND EROSION AND SEDIMENTATION CONTROL PLAN 5.1 Introduction The following sections describe the potential pollutant sources, controls to reduce the pollutants, construction sequence, and construction and earth movement schedules related to the project's soil disturbance. The Erosion and Sedimentation Control Plans (CE series) can be found under separate cover submitted with this report. 5.2 Construction Sequence The total limit of disturbance of the proposed development is approximately 0.66 acres. Installation of erosion and sediment control controls! Earthwork, site utilities, retaining wall, and stormwater management facilities, construction of building, final site paving, striping, site stabilization, and plantings. Duration: ±9 months. 1. A pre-construction meeting shall be held by all members of the project team prior to land disturbing activities to discuss project staging and installation of erosion controls. Notify all appropriate town departments prior to commencement of on-site activities and in accordance with all approvals. 2. Construct stabilized construction exits and entrances and install all required soil erosion and sediment controls: compost filter tubes or silt fences and inlet LA/V&A/V protection at locations as shown on Soil Erosion & Sediment Control sheet (CE 100 series). 3. Perform tree clearing. Stumping and grubbing shall be phased to the extent feasible to limit exposed soil. Additional erosion controls may be required, at the expense of the contractor, to compensate for stump and ground cover removal. 4. Begin earthwork, mass grading & site preparation, creation of soil and vegetation stockpiles requiring stabilization, retaining wall construction, and site utilities construction. Note: for stockpiles that will be unused for 14 or more days, provide cover or temporary stabilization. 5. Implement and maintain stabilization measures (e.g. seeding protected by erosion controls until vegetation is established, sodding, mulching erosion control blankets, hydromulch, gravel, etc.) that minimize erosion from exposed portions of the site. 6. Begin building construction 7. Establish uniform, perennial vegetation that provides 70 percent or more of the cover that is provided by vegetation native to local undisturbed areas for final stabilization. 8. Complete building and site construction. 9. Remove all soil erosion and sediment control measures, only after all exposed earth surfaces are stabilized. 10. Remove stabilized construction exits/entrances only prior to pavement construction in these areas. Removal of all construction equipment and vehicles. 5.3 Construction Period Pollution Prevention Controls Best Management Practices (BMPs) will be utilized as Construction Period Pollution Prevention Controls to reduce potential pollutants and prevent any off-site discharge. The objectives of the BMPs for construction activity are to minimize the disturbed areas, stabilize any disturbed areas, control the site perimeter and retain sediment. The contractor will minimize the area disturbed by construction activities to reduce the potential for soil erosion and stormwater pollution problems. In addition, good housekeeping measures will be followed for the day-to-day operation of the construction site under the control of the contractor to minimize the impact of construction. This section describes the control practices that will be in place during construction activities. 5.3.1 Perimeter Controls Perimeter controls for this project will consist of the installation of a perimeter silt fence or compost filter tube to prevent any soil runoff. The silt fence or LAIVGA/V compost filter tube will prevent sediment laden storm runoff from leaving the construction site or disturbed area. Perimeter controls will be installed before earth disturbing activities, pavement, and concrete slab removal. 5.3.2 Sediment Track-out Control Stabilized construction entrance and stabilized construction pads shall be established on site within the drive aisles. The construction entrances are constructed in accordance with local regulatory criteria. The entrances are located within the perimeter silt fence or compost filter tube. 5.3.3 Stockpiled Soil or Sediment As part of the sediment controls, soils will be loaded directly into dump trucks and removed from the site, or soil stockpile areas will be established on-site. The stockpile areas will be surrounded by compost filter tube and silt fencing and stabilized if unused for more than 14-days (e.g., hydroseed with an appropriate annual or winter rye seed mix and tackifier). The initial stockpile area will be established at the outset of the construction activities on site. As construction progresses, stockpile areas may be relocated as needed but must maintain the erosion and sediment control protection described above. 5.3.4 Dust Control Dust control will be accomplished by use of vegetative cover, mulch, spray-on adhesives, tillage, water sprinkling, dust barriers, or stone. Dust control will be applied on an as-needed basis, specifically when dry or windy weather increases site-wide dust kick-up. 5.3.5 Minimize Disturbance of Steep Slopes There are existing or proposed steep slopes at the site. In these areas the contractor will install soil erosion control blankets and provide soil roughening. Soil erosion control blankets will be installed upon completion of grading. 5.3.6 Soil Compaction The majority of proposed construction will be building, asphalt, concrete, and gravel cover. The areas of vegetation will be accessible only to lightly loaded landscape equipment or hand-operated equipment and tools. Upon completion of grading, construction equipment and activities are to be avoided within areas designed for infiltration. LAIVGA/V 5.3.7 Storm Drain Inlet Protection At-grade inlets and curb inlets will be provided with inlet protection throughout the construction activities until final stabilization is achieved. This inlet protection will be installed at the onset of the construction activities. The inlet protection shall consist of a silt filter bag which is placed under the grate. Filter tubes may be placed around catch basins after the initial grading to filter and divert sediment until final paving is complete. 5.3.8 Dewatering Based on the proposed construction activities, the depths of proposed excavations, and the known ground water table elevation, dewatering practices are anticipated to be required for deeper excavations, foundations, and site features. Water infiltration to the foundation excavation can likely be controlled using gravity-fed sump pumps via gravel trenches or sumps assisted with collector trenches. The dewatering measures implemented should adequately dewater all foundation-related excavations such that compaction of footing subgrades is feasible. All dewatering activities shall be supervised and witnessed by the designated erosion control monitor. Dewatering activities shall be monitored daily by the erosion control monitor to ensure that sediment laden water is appropriately settled prior to discharge. 5.3.9 Site Stabilization During construction, any area of exposed soils that will be left idle for more than 30 days shall be stabilized with a layer of mulch hay. For areas that are not meant to remain actively utilized, stabilization procedures will occur on the following schedule: • Initiate the installation of stabilization measures immediately in any areas of exposed soil where construction activities have permanently ceased or will be temporarily inactive for 14 or more calendar days. • Complete the installation of stabilization measures as soon as practicable, but no later than 14 calendar days after stabilization has been initiated. All exposed soil finish grade surfaces shall be immediately landscaped and stabilized, loamed, seeded, and mulched with a layer of mulch hay. All disturbed areas must be graded, loamed, and seeded prior to November 1 st of each year. Outside of the growing season, beyond November 15th of any construction year, exposed soil finish grade surfaces shall be stabilized with a layer of mulch LAIVGA/V hay, straw, tackifier or biodegradable erosion control blanket until climate conditions allow for seeding. All temporary erosion and sedimentation controls will be removed after final site stabilization. 5.4 Pollution Prevention Standards Potential sources of pollution during construction are: • sediment from exposed soils and dewatering • construction material debris • human waste • concrete washout • diesel, gasoline, and hydraulic and engine oil All sources of soil erosion pollution or construction pollution to stormwater bodies will be mitigated with the use of silt fence, compost filter tubes, and construction fencing around the construction area. To prevent prohibited non-stormwater discharge the good housekeeping practices must be followed. 5.4.1 Spill Prevention and Response The Contractor will be responsible for preventing spills in accordance with the project specifications and applicable federal, state and local regulations. The Contractor will identify a properly trained site employee, involved with the day- to-day site operations to be the spill prevention and cleanup coordinator. The name(s) of the responsible spill personnel will be posted on-site. Each employee will be instructed that all spills are to be reported to the spill prevention and cleanup coordinator. The supervisor will assess the incident and initiate proper containment and response procedures immediately upon notification. Workers should avoid direct contact with spilled materials during the containment procedures. Primary notification of a spill should be made to the local Fire Department and Police Departments. Secondary notification will be to the certified cleanup contractor if deemed necessary by fire and police personnel. The third level of notification (within 1 hour) is to the DEP or municipality's Licensed Site Professional (LSP). The specific cleanup contractor to be used will be identified by the Contractor prior to commencement of construction activities. LAIVGA/V 5.4.2 Designated Washout Areas Concrete waste will be placed in designated dumpster (or comparable structure) and concrete washout will occur in designated containment areas. 5.4.3 Proper Equipment, Vehicle Fueling, and Maintenance Practices On-site vehicles will be monitored for leaks and receive regular preventative maintenance off-site to reduce the risk of leakage. To ensure that leaks on stored equipment do not contaminate the site, oil-absorbing mats will be placed under oil-containing equipment during storage. Refueling will occur outside wetland resource areas and buffers. Any petroleum products will be stored in tightly sealed containers that are clearly labeled with spill control pads/socks placed under/around their perimeters. 5.4.4 Equipment and Vehicle Washing No equipment, vehicles, and machines will be washed on-site. 5.4.5 Spill Control Equipment Spill control and containment equipment will be kept in the work area. Materials and equipment necessary for spill cleanup will be kept either in the work area or in an otherwise accessible on-site location. Equipment and materials will include, but not be limited to, absorbent booms and mats, brooms, dust pans, mops, rags, gloves, goggles, sand, plastic and metal containers specifically for this purpose. It is the responsibility of the contractor to ensure the inventory will be readily accessible and maintained. 5.4.6 Spill Containment and Clean-Up Measures Spills will be contained with granular sorbent material, sand, sorbent pads, booms or all of the above to prevent spreading. Certified cleanup contractors should complete spill cleanup. The material manufacturer's recommended methods for spill cleanup will be clearly posted and on-site personnel will be made aware of the procedures and the location of the information and cleanup supplies. 5.4.7 Hazardous Materials Spill Report The contractor will report and record any spill. The spill report will present a description of the release, including the quantity and type of material, date of the spill, circumstances leading to the release, location of spill, response actions and LAIVGA/V personnel, documentation of notifications and corrective measures implemented to prevent reoccurrence. This document does not relieve the Contractor of the Federal reporting requirements of 40 CFR Part 110, 40 CFR Part 1171 40 CFR Part 302 and the State requirements specified under the Massachusetts Contingency Plan (M.C.P) relating to spills or other releases of oils or hazardous substances. Where a release containing a hazardous substance or oil in an amount equal to or in excess of a reportable quantity established under either 40 CFR Part 110, 40 CFR Part 117 or 40 CFR Part 302, occurs during a twenty-four (24) hour period, the Contractor is required to comply with the response requirements of the above mentioned regulations. Spills of oil or hazardous material in excess of the reportable quantity will be reported to the National Response Center (NRC). 5.5 Operation and Maintenance of Erosion Control The erosion control measures will be installed as detailed on the drawings (CE series). If there is a failure to the controls the contractor, under the supervision of the engineer, will be required to stop work until the failure is repaired. Periodically throughout the work, whenever the engineer deems it necessary, the sediment that has been deposited against the controls will be removed to ensure that the controls are working properly. 5.6 Inspection Schedule During construction, the erosion and sedimentation controls will be inspected as detailed on the drawings. Once the Contractor is selected, an on-site inspector will be selected to work closely to make sure that erosion and sedimentation controls are in place and working properly. The Owner must schedule the following site inspections: 1 . Initial Site Inspection: prior to approval of any Plan. 2. Project Progress Inspections: observe and document project progress at certain milestones. a) Erosion and sediment control measures are in place and stabilized; b) Site Clearing has been substantially completed; c) Rough Grading has been substantially completed; d) Final Grading has been substantially completed; e) Close of the Construction Season; f) Final Landscaping (permanent stabilization) g) Project final completion. LAIVGA/V 3. Owner Inspections: weekly inspections and prior to and following any storm events with over 0.25" of precipitation. 4. Bury Inspection: prior to backfilling of drainage piping or stormwater conveyance structures. 5. Final Inspection: after construction is completed. 6.0 CONCLUSION The proposed stormwater management system has been designed in accordance with the town of North Andover Stormwater Management and Erosion Control Regulations, Massachusetts Stormwater Management Handbook, and the Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas. The system incorporates stormwater quality measures and maintains or decreases the existing rate of runoff for all storm events analyzed. We believe based on the findings of this report that the proposed stormwater system, as designed, will effectively manage quality and quantity of stormwater runoff for the proposed redevelopment. LA/V&A/V 7.0 REFERENCES 1. Stormwater Management Handbook, Massachusetts Department of Environmental Protection, 2008. 2. Hydrology Handbook for Conservation Commissioners, Massachusetts Department of Environmental Protection, 2002. 3. Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas, Department of Environmental Protection, Bureau of Resource Protection, May 2003. 4. Precipitation Frequency Data Server (PFDS) National Weather Service (NOAA). 5. USGS Web Soil Survey, United States National Resources Conservation Service, 2016. 6. Urban Hydgy for Small Watersheds, Technical Release 55, United States Department of Agriculture, Soil Conservation Service, June 1986. 7. Massachusetts Small MS4 General Permit 2016 Final Permit, effective July 1, 2018. 8. Project Development and Design Guide, Chapter 8 Drainage and Erosion Control, Massachusetts Department of Transportation, 2006. 9. Stormwater Management and Erosion Control Regulations, Town of North Andover, 2022. Wan gan.com\data\BOS\Data5\151028501\Project Data\_Discipline\Site Civil\Reports\Stormwater\149 Main Street Stormwater Management Report Narrative.docx LA/VGA/V 2 v) 3 4 rew McEvoy Naygr"OL,Irid A 71 0 Suttons Mills 1�v e N sutt'01,7 Por"id r otk' B e' SITEZ North And�over Q7 ur0on St r st C t,A ck d e S t af 0\ DI" St A 70ft 11R§ 'A eS D 41, 41 C" Al Legend NOTES: 1,WORLD TOPOGRAPHIC BASEMAP IS PROVIDED THROUGH 800 0 800 LANGAN'S ESRI AND ARC S SOFTWARE LICENSING AND Approximate Site Boundary I I ARC SCALE IN FEET' GIS ONLINE, 9 Project Figure Title Project No. Figure No. L A 151028501 100 Carribridge Street,Suite 1310 Date Boston,MA 02114 11/14/2022 T 617-824-9100 F:617-824-9101 www.larigari.com 14!9` MA1N" ST OK"'EET 'ITE L"'C"I Ar"N Scale Langan Engineering&Environmental Services,Inc- 1 11=800' Langan Engineering,Environmental,Surveying, NORTH ANDOVER MAP Drawn By Landscape Architecture and Gedogy,D,P.C. MG angan lnternafional I LC Submission Date Collectively known as Langan ESSEX COUNTY MASSACHUSETTS cv Path:\\Iangan.corn\data\l3OS\Data5\1 51028501\Project Data\,ArcGIS\APRXN151028501\151028501,aprx Date:11/14/2022 User:mgeorgalas Time:11:30 AM 1 2 3 4 A *-A B FFI( C OPP` i"AAM11.................. V, D W Legend, NOTES: 1.AERIAL IMAGERY PROVIDED THROUGH LANGAN'S SUBSCRIPTION Approximate Site Boundary 300 0 300 TO NEAR MAP,DATED 09/24/2022. 2.FLOOD DATA PROVIDED BY FEMA. SCALE IN FEET Zone AE Project Figure Title Project No. Figure No. LA/VGA/%/ 151028501 100 Carribridge Street,Suite 1310 Date Boston,MA 02114 11/14/2022 T 617-824-9100 F�617-824-9101 www.larigari.com 149) MAINSTREET NAN'T Scale 2 Langan Engineering&Environmental Services,Inc- FEMA PRELIMUL K 111=300' Langan Engineering,EnvironmentW,Surveying, NORTHANDOVER FLOOE)" MAP Drawn By Landscape Architecture and Gedogy,D,P.C. MG angan lnternafiona�I LC C14 Submission Date Collectively known as Langan ESSEX COUNTY MASSACHUSETTS C14 WINNOW 1 '11 111111 1 0 Path:\\Iangan.corn\data\l30S\Data5\1 51028501\Project Data\,ArcGIS\APRXN151028501\151028501,aprx Date:11/14/2022 User:mgeorgalas Time:11:30 AM 2 3 ..... ft. 4 P" .......... A '15' fe, A F, q A A, ""7 Al" B jq R j*' IF, C ff "fw S, uj$ 01 /6 AT "Ad AJ/1 Legend NOTES: 1.AERIAL IMAGERY PROVIDED THROUGH LANGAN'S SUBSCRIPTION Approximate Site Boundary 100 0 100 TO NEAR MAP,DATED 09/24/2022. SCALE IN FEET Project Figure Title Project No. Figure No. LA/VGA/%/ 151028501 100 Carribridge Street,Suite 1310 Date Boston,MA 02114 11/14/2022 T 617-824-9100 F�617-824-9101 www.larigari.com 14!9" MAIN STREET Scale Langan Engineering&Environmental Services,Inc- AERIAL MAP 111=100' Langan Engineering,EnvironmentW,Surveying, NORTHANDOVER Drawn By Landscape Architecture and Gedogy,D,P.C. MG angan lnternafiona�I LC C14 Submission Date Collectively known as Langan ESSEX COUNTY MASSACHUSETTS C14 WINNOW 1 '11 111111 1 0 Path:\\1angan.corn\data\B0S\Data5\1 51028501\Project Data\,ArcGIS\APRXN151028501\151028501,aprx Date:11/14/2022 User:mgeorgalas Time:11:30AM 3 4 Vw ,, u I ul�lz It �Illlll���r,- .l ml , h i II t I,IL f• 4Y,k ^�t I .I Y / , 4 V Illllu I u,l PI II I, I l I i , � I�.i 1� IIIIIIIIIIIIIIIII �t I I I I I I i I i I I Y lily, I. I L IL. r / / f / m t t / I / l r I 1 r l i I /r �I IIlii�illl I�� III��� i / rt`/ Ilr-III . ,,,I�II� I uuluuu. i r 1 / / I t r i f i f r / r >r r 1 � 1 / r r r / IYi 11�II�� � III III I 1 II II I w N r, I r, �� rcol / / I i r � J l f I r � , I , Ir l I� 1 ,1 Y-" I / 1 ® � i I � / t / i / / �I r � l r_ r, / i / 1 I y � ( I 1 1 f r 1 , /r IYf IIIII r 1 o. f / I h I I' I I � l r 1 iti i I� / l r 1 1 I�I , 111,1 l>l1 i ��iIIIIJI � I 1�� iU I!;/r'r �UII���I i ''.filj �I,/,ill� lp000ii iiVMlui' 1 I J 1 6 / pp vuii 1 lUl p�llll I IIII�II I ,Approximate Site Boundary 405B,C Carlton fine sandy loam,3 to 3 percent slopes D , 1,Water 405C';,Charlton fine sandy loam,3 to 15 percent slopes 305B Paxton fine sandy loam,3 to 3 percent slopes 420B,Canton fine sandy loam 3 to 8 percent slopes All 310B,Woodbrid e fine sandy loam,3 to 3 percent slopes p p 420C;,Canton fine sandy loam,3 to 15 percent slopes 310C,Woodbridge fine sandy loam,3 to 15 percent slopes 602,Urban and i t7����,, aim�m�wmmr�»�d�m»iw��rluuvo!Il�uou�ulwma�a�rm�ullwl��owwur»gym aa�ur�o»u,w ,na�oti�rr� � Iwmom,�l»r�r�»000mrv�uil�,�lwa ~dme tmww�», ,�»»�nlo� ��r��rraaenr nnawr �ro»tr»mlmw�m�umauurvuwMsmu��v�i�iiaii �oa�o�r�cu�l���n�li u!wu!wllmlmlwialmauo��lu�ceummom� �wv�rn��waummi�utmsn!,bdm�wmmll,uir�mwa�,mwml�aa�umnlnmw�romia�r� �nmsmro»uwwau�r��amuamlru�o� ,, NOTES: 1.AERIAL IMAGERY PROVIDED THROUGH LA GAN'S SUBSCRIPTION 300 0 300 TO NEAR MAP„DATED 09/24/2022. 2.SOIL DATA PROVIDED BY USDA NATURAL RESOURCES SCALE IN FEET CONSERVATION SERVICE. Project Figure Title Project No. Figure No. L A/VGA 151028501 100 C arribrrdgea Street,Suite 1310 Date Boston,MA 02114 14!961MA1N STREET 11 f 14/2C)22 T:617-624-9100 F:617-824-9101 wwwovww.larigari.com N RCS Scale Langan Engineering&Environmental Services,Inc. 1 11=300' Langan Engineering,Envrorament<W,Surveying, ORTH ANDOVEI S I L AP Drawn S Landscape rchitectur and Gedogy„D,P.0. MG q angan lnternahonal I.LC c Submission Date Collectively known as Langan ESSEX COUNTY MASSAC USETTS cv Path:\\1an n.corn\ a\B0S\Dat 5\1 510285011l r je I a 1,r GIS PRXN1 1C28501\1 10 01, rx Date:11/14/0 User:mg or ala Time:11:31 AM APPENDIX A Existing Stormwater Discharge Calculations LA/VEA/V 1 2 3 4 5 6 7 8 Z Z A )001 y Cl) z WATERSHED A-0 IMPERVIOUS AREA-1,32S SF PERVIOUS AREA--0 SF TOTAL AREA.1,325 SF CN.98 TC-6 MIN. B 1 WUW U ERVIODS AREA-293 SF PERVIOUS nRrw-0SF , TOTALA 293 SF ' TCr6MIN. WATERSHED A IMPERVIOUS AREA—7,342 SF PERVIOUS AREA.610 SF TOTAL AREA-7,9S2 SF CN-9S WATERSHED BOUWDARY----------4 1 *v, 7 �O l �j/OO �v �"',� loll 1 .. IMPERVIOUS AREAw 7,474 SF DESIGN POINT A —// PERVIOUS AREA.3,134 SF / J' MAIN STREET f TOTAL AREA-20AW SF J\ J CN-92 / TC 6 MIN. TIME OF CONCENTRATION PATH Data Description No. Revisions _ I >+DESIGN POINT B - N SEND STREET SECOND STREET LANGAN Langan Engineering and Environmental Services,Inc. 100 Cambridge Street,Suite 1310 Boston.MA02114 617 824 9100 F 617 824 9101 www.langan.com Project 149 MAIN STREET, NORTH ANDOVER E NORTH ANDOVER _. ESSEX COUNTY AMSSACHUSETTS Drawing Title EXISTING DRAINAGE AREA PLAN Project No. Drawing No. 151028501 20 0 10 20 Date [[�� SCALE IN FEET 2022-09 2 EX WJ Drawn By F ARK Checked By HH Sheet 0 of 1 Date:12t3012022 Time:09:27 User:mgallucci Style Table:Langan.stb Layout:EX-WS Document Cade:151028501-0301-CG103-0101 A-0 A B B-0 Offsite to Main St et To ain Street To Second treet Off ' e to Second Street AL BL Main Street Second Street 4ubca Reach Pond Link Routing Diagram for Existing Conditions Prepared by Langan Engineering, Printed 12/30/2022 HydroCAD®10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC 149 Main St Existing Conditions Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 2 Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 0.086 61 >75% Grass cover, Good, HSG B (A, B) 0.570 98 Impervious Area (A, B) 0.037 98 Roofs, HSG B (A-O) B-O) 0.693 93 TOTAL AREA 149 Main St Existing Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 3 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA: To Main Street Runoff Area=7,952 sf 92.33% Impervious Runoff Depth>2.44" Flow Length=133' Tc=6.0 min CN=95 Runoff=0.51 cfs 0.037 of SubcatchmentA-O: Offsite to Main Street Runoff Area=0.030 ac 100.00% Impervious Runoff Depth>2.72" Tc=0.0 min CN=98 Runoff=0.10 cfs 0.007 of SubcatchmentB: To Second Street Runoff Area=20,608 sf 84.79% Impervious Runoff Depth>2.16" Flow Length=230' Tc=6.0 min CN=92 Runoff=1.22 cfs 0.085 of SubcatchmentB-O: Offsite to Second Runoff Area=0.007 ac 100.00% Impervious Runoff Depth>2.72" Tc=0.0 min CN=98 Runoff=0.02 cfs 0.002 of Link AL: Main Street Inflow=0.57 cfs 0.044 of Primary=0.57 cfs 0.044 of Link BL: Second Street Inflow=1.23 cfs 0.087 of Primary=1.23 cfs 0.087 of Total Runoff Area = 0.693 ac Runoff Volume = 0.131 of Average Runoff Depth = 2.27" 12.41% Pervious = 0.086 ac 87.59% Impervious = 0.607 ac 149 Main St Existing Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment A: To Main Street Runoff = 0.51 cfs @ 12.09 hrs, Volume= 0.037 af, Depth> 2.44" Routed to Link AL : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (sf) CN Description 77342 98 Impervious Area 610 61 >75% Grass cover, Good, HSG B 77952 95 Weighted Average 610 7.67% Pervious Area 77342 92.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.7 8 0.2800 0.20 Sheet Flow, Grass Grass: Dense n= 0.240 P2= 3.13" 0.3 90 0.0500 4.54 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 0.2 35 0.0200 2.87 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 1.2 133 Total, Increased to minimum Tc = 6.0 min 149 Main St Existing Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment A-O: Offsite to Main Street Runoff = 0.10 cfs @ 12.00 hrs, Volume= 0.007 af, Depth> 2.72" Routed to Link AL : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (ac) CN Description 0.030 98 Roofs, HSG B 0.030 100.00% Impervious Area 149 Main St Existing Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment B: To Second Street Runoff = 1.22 cfs @ 12.09 hrs, Volume= 0.085 af, Depth> 2.16" Routed to Link BL : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (sf) CN Description 31134 61 >75% Grass cover, Good, HSG B 171474 98 Impervious Area 207608 92 Weighted Average 31134 15.21% Pervious Area 177474 84.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 11 0.1400 0.16 Sheet Flow, Grass Grass: Dense n= 0.240 P2= 3.13" 1.0 219 0.0300 3.52 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 2.1 230 Total, Increased to minimum Tc = 6.0 min 149 Main St Existing Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment B-O: Offsite to Second Street Runoff = 0.02 cfs @ 12.00 hrs, Volume= 0.002 af, Depth> 2.72" Routed to Link BL : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (ac) CN Description 0.007 98 Roofs, HSG B 0.007 100.00% Impervious Area 149 Main St Existing Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 8 Summary for Link AL: Main Street Inflow Area = 0.213 ac, 93.41% Impervious, Inflow Depth > 2.48" for 2-yr event Inflow = 0.57 cfs @ 12.08 hrs, Volume= 0.044 of Primary = 0.57 cfs @ 12.08 hrs, Volume= 0.044 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 149 Main St Existing Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 9 Summary for Link BL: Second Street Inflow Area = 0.480 ac, 85.01% Impervious, Inflow Depth > 2.17" for 2-yr event Inflow = 1.23 cfs @ 12.09 hrs, Volume= 0.087 of Primary = 1.23 cfs @ 12.09 hrs, Volume= 0.087 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 149 Main St Existing Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 10 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA: To Main Street Runoff Area=7,952 sf 92.33% Impervious Runoff Depth>4.14" Flow Length=133' Tc=6.0 min CN=95 Runoff=0.84 cfs 0.063 of SubcatchmentA-O: Offsite to Main Street Runoff Area=0.030 ac 100.00% Impervious Runoff Depth>4.40" Tc=0.0 min CN=98 Runoff=0.17 cfs 0.011 of SubcatchmentB: To Second Street Runoff Area=20,608 sf 84.79% Impervious Runoff Depth>3.85" Flow Length=230' Tc=6.0 min CN=92 Runoff=2.09 cfs 0.152 of SubcatchmentB-O: Offsite to Second Runoff Area=0.007 ac 100.00% Impervious Runoff Depth>4.40" Tc=0.0 min CN=98 Runoff=0.04 cfs 0.003 of Link AL: Main Street Inflow=0.93 cfs 0.074 of Primary=0.93 cfs 0.074 of Link BL: Second Street Inflow=2.11 cfs 0.154 of Primary=2.11 cfs 0.154 of Total Runoff Area = 0.693 ac Runoff Volume = 0.228 of Average Runoff Depth = 3.95" 12.41% Pervious = 0.086 ac 87.59% Impervious = 0.607 ac 149 Main St Existing Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 11 Summary for Subcatchment A: To Main Street Runoff = 0.84 cfs @ 12.09 hrs, Volume= 0.063 af, Depth> 4.14" Routed to Link AL : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (sf) CN Description 77342 98 Impervious Area 610 61 >75% Grass cover, Good, HSG B 77952 95 Weighted Average 610 7.67% Pervious Area 77342 92.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.7 8 0.2800 0.20 Sheet Flow, Grass Grass: Dense n= 0.240 P2= 3.13" 0.3 90 0.0500 4.54 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 0.2 35 0.0200 2.87 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 1.2 133 Total, Increased to minimum Tc = 6.0 min 149 Main St Existing Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 12 Summary for Subcatchment A-O: Offsite to Main Street Runoff = 0.17 cfs @ 12.00 hrs, Volume= 0.011 af, Depth> 4.40" Routed to Link AL : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (ac) CN Description 0.030 98 Roofs, HSG B 0.030 100.00% Impervious Area 149 Main St Existing Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 13 Summary for Subcatchment B: To Second Street Runoff = 2.09 cfs @ 12.09 hrs, Volume= 0.152 af, Depth> 3.85" Routed to Link BL : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (sf) CN Description 31134 61 >75% Grass cover, Good, HSG B 171474 98 Impervious Area 207608 92 Weighted Average 31134 15.21% Pervious Area 177474 84.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 11 0.1400 0.16 Sheet Flow, Grass Grass: Dense n= 0.240 P2= 3.13" 1.0 219 0.0300 3.52 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 2.1 230 Total, Increased to minimum Tc = 6.0 min 149 Main St Existing Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 14 Summary for Subcatchment B-O: Offsite to Second Street Runoff = 0.04 cfs @ 12.00 hrs, Volume= 0.003 af, Depth> 4.40" Routed to Link BL : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (ac) CN Description 0.007 98 Roofs, HSG B 0.007 100.00% Impervious Area 149 Main St Existing Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 15 Summary for Link AL: Main Street Inflow Area = 0.213 ac, 93.41% Impervious, Inflow Depth > 4.18" for 10-yr event Inflow = 0.93 cfs @ 12.08 hrs, Volume= 0.074 of Primary = 0.93 cfs @ 12.08 hrs, Volume= 0.074 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 149 Main St Existing Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 16 Summary for Link BL: Second Street Inflow Area = 0.480 ac, 85.01% Impervious, Inflow Depth > 3.85" for 10-yr event Inflow = 2.11 cfs @ 12.09 hrs, Volume= 0.154 of Primary = 2.11 cfs @ 12.09 hrs, Volume= 0.154 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 149 Main St Existing Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 17 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA: To Main Street Runoff Area=7,952 sf 92.33% Impervious Runoff Depth>5.20" Flow Length=133' Tc=6.0 min CN=95 Runoff=1.05 cfs 0.079 of SubcatchmentA-O: Offsite to Main Street Runoff Area=0.030 ac 100.00% Impervious Runoff Depth>5.45" Tc=0.0 min CN=98 Runoff=0.21 cfs 0.014 of SubcatchmentB: To Second Street Runoff Area=20,608 sf 84.79% Impervious Runoff Depth>4.91" Flow Length=230' Tc=6.0 min CN=92 Runoff=2.64 cfs 0.193 of SubcatchmentB-O: Offsite to Second Runoff Area=0.007 ac 100.00% Impervious Runoff Depth>5.45" Tc=0.0 min CN=98 Runoff=0.05 cfs 0.003 of Link AL: Main Street Inflow=1.16 cfs 0.093 of Primary=1.16 cfs 0.093 of Link BL: Second Street Inflow=2.66 cfs 0.197 of Primary=2.66 cfs 0.197 of Total Runoff Area = 0.693 ac Runoff Volume = 0.289 of Average Runoff Depth = 5.01" 12.41% Pervious = 0.086 ac 87.59% Impervious = 0.607 ac 149 Main St Existing Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 18 Summary for Subcatchment A: To Main Street Runoff = 1.05 cfs @ 12.09 hrs, Volume= 0.079 af, Depth> 5.20" Routed to Link AL : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (sf) CN Description 77342 98 Impervious Area 610 61 >75% Grass cover, Good, HSG B 77952 95 Weighted Average 610 7.67% Pervious Area 77342 92.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.7 8 0.2800 0.20 Sheet Flow, Grass Grass: Dense n= 0.240 P2= 3.13" 0.3 90 0.0500 4.54 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 0.2 35 0.0200 2.87 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 1.2 133 Total, Increased to minimum Tc = 6.0 min 149 Main St Existing Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 19 Summary for Subcatchment A-O: Offsite to Main Street Runoff = 0.21 cfs @ 12.00 hrs, Volume= 0.014 af, Depth> 5.45" Routed to Link AL : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (ac) CN Description 0.030 98 Roofs, HSG B 0.030 100.00% Impervious Area 149 Main St Existing Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 20 Summary for Subcatchment B: To Second Street Runoff = 2.64 cfs @ 12.09 hrs, Volume= 0.193 af, Depth> 4.91" Routed to Link BL : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (sf) CN Description 31134 61 >75% Grass cover, Good, HSG B 171474 98 Impervious Area 207608 92 Weighted Average 31134 15.21% Pervious Area 177474 84.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 11 0.1400 0.16 Sheet Flow, Grass Grass: Dense n= 0.240 P2= 3.13" 1.0 219 0.0300 3.52 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 2.1 230 Total, Increased to minimum Tc = 6.0 min 149 Main St Existing Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 21 Summary for Subcatchment B-O: Offsite to Second Street Runoff = 0.05 cfs @ 12.00 hrs, Volume= 0.003 af, Depth> 5.45" Routed to Link BL : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (ac) CN Description 0.007 98 Roofs, HSG B 0.007 100.00% Impervious Area 149 Main St Existing Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 22 Summary for Link AL: Main Street Inflow Area = 0.213 ac, 93.41% Impervious, Inflow Depth > 5.24" for 25-yr event Inflow = 1.16 cfs @ 12.08 hrs, Volume= 0.093 of Primary = 1.16 cfs @ 12.08 hrs, Volume= 0.093 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 149 Main St Existing Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 23 Summary for Link BL: Second Street Inflow Area = 0.480 ac, 85.01% Impervious, Inflow Depth > 4.91" for 25-yr event Inflow = 2.66 cfs @ 12.09 hrs, Volume= 0.197 of Primary = 2.66 cfs @ 12.09 hrs, Volume= 0.197 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 149 Main St Existing Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 24 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA: To Main Street Runoff Area=7,952 sf 92.33% Impervious Runoff Depth>7.65" Flow Length=133' Tc=6.0 min CN=95 Runoff=1.53 cfs 0.116 of SubcatchmentA-O: Offsite to Main Street Runoff Area=0.030 ac 100.00% Impervious Runoff Depth>7.87" Tc=0.0 min CN=98 Runoff=0.30 cfs 0.020 of SubcatchmentB: To Second Street Runoff Area=20,608 sf 84.79% Impervious Runoff Depth>7.37" Flow Length=230' Tc=6.0 min CN=92 Runoff=3.88 cfs 0.291 of SubcatchmentB-O: Offsite to Second Runoff Area=0.007 ac 100.00% Impervious Runoff Depth>7.87" Tc=0.0 min CN=98 Runoff=0.07 cfs 0.005 of Link AL: Main Street Inflow=1.69 cfs 0.136 of Primary=1.69 cfs 0.136 of Link BL: Second Street Inflow=3.92 cfs 0.295 of Primary=3.92 cfs 0.295 of Total Runoff Area = 0.693 ac Runoff Volume = 0.431 of Average Runoff Depth = 7.47" 12.41% Pervious = 0.086 ac 87.59% Impervious = 0.607 ac 149 Main St Existing Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 25 Summary for Subcatchment A: To Main Street Runoff = 1.53 cfs @ 12.09 hrs, Volume= 0.116 af, Depth> 7.65" Routed to Link AL : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (sf) CN Description 77342 98 Impervious Area 610 61 >75% Grass cover, Good, HSG B 77952 95 Weighted Average 610 7.67% Pervious Area 77342 92.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.7 8 0.2800 0.20 Sheet Flow, Grass Grass: Dense n= 0.240 P2= 3.13" 0.3 90 0.0500 4.54 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 0.2 35 0.0200 2.87 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 1.2 133 Total, Increased to minimum Tc = 6.0 min 149 Main St Existing Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 26 Summary for Subcatchment A-O: Offsite to Main Street Runoff = 0.30 cfs @ 12.00 hrs, Volume= 0.020 af, Depth> 7.87" Routed to Link AL : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (ac) CN Description 0.030 98 Roofs, HSG B 0.030 100.00% Impervious Area 149 Main St Existing Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 27 Summary for Subcatchment B: To Second Street Runoff = 3.88 cfs @ 12.09 hrs, Volume= 0.291 af, Depth> 7.37" Routed to Link BL : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (sf) CN Description 31134 61 >75% Grass cover, Good, HSG B 171474 98 Impervious Area 207608 92 Weighted Average 31134 15.21% Pervious Area 177474 84.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 1.1 11 0.1400 0.16 Sheet Flow, Grass Grass: Dense n= 0.240 P2= 3.13" 1.0 219 0.0300 3.52 Shallow Concentrated Flow, Paved Paved Kv= 20.3 fps 2.1 230 Total, Increased to minimum Tc = 6.0 min 149 Main St Existing Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 28 Summary for Subcatchment B-O: Offsite to Second Street Runoff = 0.07 cfs @ 12.00 hrs, Volume= 0.005 af, Depth> 7.87" Routed to Link BL : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (ac) CN Description 0.007 98 Roofs, HSG B 0.007 100.00% Impervious Area 149 Main St Existing Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 29 Summary for Link AL: Main Street Inflow Area = 0.213 ac, 93.41% Impervious, Inflow Depth > 7.69" for 100-yr event Inflow = 1.69 cfs @ 12.08 hrs, Volume= 0.136 of Primary = 1.69 cfs @ 12.08 hrs, Volume= 0.136 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 149 Main St Existing Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 30 Summary for Link BL: Second Street Inflow Area = 0.480 ac, 85.01% Impervious, Inflow Depth > 7.38" for 100-yr event Inflow = 3.92 cfs @ 12.09 hrs, Volume= 0.295 of Primary = 3.92 cfs @ 12.09 hrs, Volume= 0.295 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs APPENDIX B Proposed Stormwater Discharge Calculations LA/VEA/V 1 2 3 4 5 6 7 8 2 Q, A 4 s -�A sP z ��., CL MAP 41 LOT 5 ' ST.GREGORY ; ARMEN/AN APOSTOLIC \ #158 MAIN STREET a, s AA 30 LOT 9 SPESj�P�lr7L'E14REN A. WATERSHED A-0 \ / #159 MAIN S7NGiFT IMPERVIOUS AREA.1,618 SF s � PERVIOUS All 0 SIF TOTAL AREA--1,618 SF DESIGN POINT A CN=98 MAIN STREET _� '' TC--6 MIN. DARY TIME OF CONCENTRATION PATH MAP 3O LOT 34 WATERSHED BOUN - t j\ -� I MAC GREGOR,DA WD G WATERSHEDM2 J{761 MAIN STREET IMPERVIOUS AREA.6,044 SF WATERSHED 0-2 " WATERSHED A-1 PERVIOUS AREA-1,146 SIF \ IMPERVIOUS AREA.2,194 SF IMPERVIOUS AREA-429 SF - TOTAL AREA--7,190 SIF \\\ PERVIOUS AREA.267 SF 'a ' PERVIOUS AREA=44 SF CN=92 m TOTAL AREA--2,461 SF TOTAL AREA.473 SF L TC=6A MIN. VCID CN_94 ON•95 TC=6.0 MIN. ' c TC=6 MIN. Q O u UNDERGROUND INFILTRATIONIDETENTION SYSTEM Do 0 i rn O 'N ZN rn MAP 41 LOT 33r] WATERSHED B-3 i .`. IMPERVIOUS AREA.1,676 SF BANK OF AMERICA #154 MAW STREET � ��i ''' � A- ..... ��� PERVIOUS AREA=1,073 SF 0 i WATERSHED B 1 IMPERVIOUS AREA-14,795 SF CCN TOTAL 2,749 SF TOTAL AREA-14,795 SIF » r TC=6.0 MIN. T_ CN.98 > TCr 6.0 MIN. 02/14/2023 TOWN REVIEW COMMENTS 1 MAP 30 LOT 28 SLEA70R SHEERA f26 SECONDc NET Date Description No. ... _ #28 SECOND STREET Revisions e 100 1 - A_e.m 4 o SECOND STREET WATERSHED B-4 IMPERVIOUS AREA-- SF :PERVIOUS AREA-92 SF -- - ' "" .... TOTAL AREA-892 SF LANGAN .. �- CN.94 Langan Engineering and .. TC.6 MIN. -DESIGN POINT Bz i SECOND STREET � Environmental Services,Inc. '' --- 100 Cambridge Street,Suite 1310 MAP 30 LOT 32 ,. _ ,.. .. '.�. _ ;: e_ ........... .. ...................................... �._�__�.�. Boston,MA 02114 GULBAS KANBAR ._ ...._ 150 MAIN STREET ................ T:617.824.9100 F:617.824.9101 www.langan.com 1 t Pro ec MAP 30 LOT 2 MAP 30 LOT 3 MAP 30 LOT 1 MAP 30 LOT 36 `��MAIN STREET OLYMPIA IV REALTY TRUST. FA Y,EUGENE NA MAIN STREET 19-25 SECOND STREET LLC A //137 MAIN STREET ill SECOND STREET LLC J/ SECOND STREET 19 - a s f/129 MAIN STREET a a NORTH AN DOVER E MAP 4O.A LOT 4 NORTH ANDOVER STONE MILL REALTY TRUST ESSEXCOUNTY AMSSACFiUSETTS #146 MAIN STREET _ Drawing Title .................1111-� .... PROPOSED DRAINAGE AREA PLAN Project No. Drawing No. -.-.- 151028501 20 0 10 20 Date SCALE IN FEET 11 2-2022 P R WS Drawn By F ARK Checked By HH Sheet 0 of a Date:2/14/2023 Time:12:23 User hholmes Style Table:Langan.stb Layout.PR-WS Document Code:151028501-0301-CG104-0101 A-2 Offsite E Parking Lot -2 DP-A DP-B 6-3 SW Pa Lot TD104 TD104 Main Street Sidewalk To Main Street Building Infiltration System Seconrtreet NW Parking Lot Sidewalk To Second Street u bcat Pond Reach Pond Link Link Routing Diagram for Proposed Conditions Prepared by Langan Engineering, Printed 12/30/2022 HydroCAD®10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC 149 Main St Proposed Conditions Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 2 Area Listing (all nodes) Area CN Description (acres) (subcatchment-numbers) 0.060 61 >75% Grass cover, Good, HSG B (A-1, A-2, B-2, B-3, B-4) 0.595 98 Paved parking, HSG B (A-1, A-2, B-1, B-2, B-3, B-4) 0.037 98 Roofs, HSG B (A-O) 0.693 95 TOTAL AREA 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 3 Time span=0.00-48.00 hrs, dt=0.04 hrs, 1201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA-1:SidewalkTo Main Street Runoff Area=473 sf 90.70% Impervious Runoff Depth=2.59" Flow Length=25' Slope=0.0150 '/' Tc=6.0 min CN=95 Runoff=0.03 cfs 0.002 of SubcatchmentA-2:SE Parking Lot Runoff Area=7,190 sf 84.06% Impervious Runoff Depth=2.29" Tc=6.0 min CN=92 Runoff=0.43 cfs 0.032 of SubcatchmentA-O: Offsite Runoff Area=1,618 sf 100.00% Impervious Runoff Depth=2.91" Tc=0.0 min CN=98 Runoff=0.13 cfs 0.009 of SubcatchmentB-1: Building Runoff Area=14,795 sf 100.00% Impervious Runoff Depth=2.91" Tc=6.0 min CN=98 Runoff=1.03 cfs 0.082 of SubcatchmentB-2: SW Parking Lot Runoff Area=2,461 sf 89.15% Impervious Runoff Depth=2.49" Flow Length=25' Slope=0.0150 '/' Tc=6.0 min CN=94 Runoff=0.16 cfs 0.012 of SubcatchmentB-3: NW Parking Lot Runoff Area=2,749 sf 60.97% Impervious Runoff Depth=1.63" Tc=6.0 min CN=84 Runoff=0.12 cfs 0.009 of SubcatchmentB-4: SidewalkTo Second Runoff Area=892 sf 89.69% Impervious Runoff Depth=2.49" Tc=6.0 min CN=94 Runoff=0.06 cfs 0.004 of Pond R: Infiltration System Peak Elev=98.19' Storage=1,537 cf Inflow=1.18 cfs 0.094 of Outflow=1.04 cfs 0.065 of Pond TD104:TD104 Inflow=0.50 cfs 0.041 of Primary=0.50 cfs 0.041 of Link DP-A: Main Street Inflow=0.53 cfs 0.043 of Primary=0.53 cfs 0.043 of Link DP-B: Second Street Inflow=1.21 cfs 0.078 of Primary=1.21 cfs 0.078 of Total Runoff Area = 0.693 ac Runoff Volume = 0.150 of Average Runoff Depth = 2.59" 8.69% Pervious = 0.060 ac 91.31% Impervious = 0.633 ac 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment A-1: Sidewalk To Main Street Runoff = 0.03 cfs @ 12.09 hrs, Volume= 0.002 af, Depth= 2.59" Routed to Link DP-A : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (sf) CN Description 429 98 Paved parking, HSG B 44 61 >75% Grass cover, Good, HSG B 473 95 Weighted Average 44 9.30% Pervious Area 429 90.70% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.4 25 0.0150 0.93 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.20" 0.4 25 Total, Increased to minimum Tc = 6.0 min 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment A-2: SE Parking Lot Runoff = 0.43 cfs @ 12.09 hrs, Volume= 0.032 af, Depth= 2.29" Routed to Pond TD 104 : TD 104 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (sf) CN Description 67044 98 Paved parking, HSG B 17146 61 >75% Grass cover, Good, HSG B 7,190 92 Weighted Average 17146 15.94% Pervious Area 67044 84.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment A-O: Offsite Runoff = 0.13 cfs @ 12.00 hrs, Volume= 0.009 af, Depth= 2.91" Routed to Pond TD 104 : TD 104 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (sf) CN Description 11618 98 Roofs, H S G 6 17618 100.00% Impervious Area 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment B-1: Building Runoff = 1.03 cfs @ 12.08 hrs, Volume= 0.082 af, Depth= 2.91" Routed to Pond R : Infiltration System Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (sf) CN Description 147795 98 Paved parking, HSG B 147795 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment B-2: SW Parking Lot Runoff = 0.16 cfs @ 12.09 hrs, Volume= 0.012 af, Depth= 2.49" Routed to Pond R : Infiltration System Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (sf) CN Description 27194 98 Paved parking, HSG B 267 61 >75% Grass cover, Good, HSG B 2461 94 Weighted Average 267 10.85% Pervious Area 2,194 89.15% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.4 25 0.0150 0.93 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.20" 0.4 25 Total, Increased to minimum Tc = 6.0 min 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 9 Summary for Subcatchment B-3: NW Parking Lot Runoff = 0.12 cfs @ 12.09 hrs, Volume= 0.009 af, Depth= 1.63" Routed to Link DP-B : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (sf) CN Description 17073 61 >75% Grass cover, Good, HSG B 1,676 98 Paved parking, HSG B 2749 84 Weighted Average 1,073 39.03% Pervious Area 1,676 60.97% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 10 Summary for Subcatchment B-4: Sidewalk To Second Street Runoff = 0.06 cfs @ 12.09 hrs, Volume= 0.004 af, Depth= 2.49" Routed to Link DP-B : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 2-yr Rainfall=3.14" Area (sf) CN Description 800 98 Paved parking, HSG B 92 61 >75% Grass cover, Good, HSG B 892 94 Weighted Average 92 10.31% Pervious Area 800 89.69% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type 11124-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 11 Summary for Pond R: Infiltration System Inflow Area = 0.396 ac, 98.45% Impervious, Inflow Depth = 2.85" for 2-yr event Inflow = 1.18 cfs @ 12.08 hrs, Volume= 0.094 of Outflow = 1.04 cfs @ 12.13 hrs, Volume= 0.065 af, Atten= 12%, Lag= 2.7 min Primary = 1.04 cfs @ 12.13 hrs, Volume= 0.065 of Routed to Link DP-B : Second Street Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 98.19' @ 12.13 hrs Surf.Area= 1,865 sf Storage= 1,537 cf Plug-Flow detention time= 182.1 min calculated for 0.065 of(69% of inflow) Center-of-Mass det. time= 87.1 min ( 847.8 - 760.7 ) Volume Invert Avail.Storage Storage Description #1 A 97.00' 527 cf 54.85'W x 23.69'L x 1.90'H Field A 2,466 cf Overall - 1,149 cf Embedded = 1,317 cf x 40.0% Voids #2A 97.25' 1,035 cf ACF R-Tank XD 7 x 310 Inside #1 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 310 Chambers in 31 Rows #313 97.00' 250 cf 22.04'W x 25.65'L x 1.90'H Field B 1,074 cf Overall - 449 cf Embedded = 625 cf x 40.0% Voids #413 97.25' 404 cf ACF R-Tank XD 7 x 121 Inside #3 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 121 Chambers in 11 Rows 2,215 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary 96.83' 12.0" Round Culvert L= 22.0' CPP, square edge headwall, Ke= 0.500 Inlet/ Outlet Invert= 96.83'/ 96.49' S= 0.0155 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf #2 Device 1 98.00' 4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=1.03 cfs @ 12.13 hrs HW=98.18' (Free Discharge) L1=Culvert (Passes 1.03 cfs of 3.50 cfs potential flow) L2=Sharp-Crested Rectangular Weir(Weir Controls 1.03 cfs @ 1.41 fps) 149 Main St Proposed Conditions Type 11124-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD01020-2f s/n 08223 02022 HvdroCAD Software Solutions LLC Page 12 Pond R: Infiltration System - Chamber Wizard Field A Chamber Model=ACF R-Tank XD 7 (ACF Environmental R-Tank XD) Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L= 3.7 cf 10 Chambers/Row x 1.97' Long = 19.69' Row Length +24.0" End Stone x 2 = 23.69' Base Length 31 Rows x 19.7"Wide + 24.0" Side Stone x 2 = 54.85' Base Width 3.0" Stone Base + 13.8" Chamber Height+ 6.0" Stone Cover= 1.90' Field Height 310 Chambers x 3.3 cf= 1,034.5 cf Chamber Storage 310 Chambers x 3.7 cf= 1,149.5 cf Displacement 2,466.3 cf Field- 1,149.5 cf Chambers = 1,316.8 cf Stone x 40.0%Voids = 526.7 cf Stone Storage Chamber Storage + Stone Storage= 1,561.2 cf = 0.036 of Overall Storage Efficiency = 63.3 Overall System Size = 23.69'x 54.85' x 1.90' 310 Chambers 91.3 cy Field 48.8 cy Stone 149 Main St Proposed Conditions Type 11124-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD01020-2f s/n 08223 02022 HvdroCAD Software Solutions LLC Page 13 Pond R: Infiltration System - Chamber Wizard Field B Chamber Model=ACF R-Tank XD 7 (ACF Environmental R-Tank XD) Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L= 3.7 cf 11 Chambers/Row x 1.97' Long = 21.65' Row Length +24.0" End Stone x 2 = 25.65' Base Length 11 Rows x 19.7"Wide + 24.0" Side Stone x 2 = 22.04' Base Width 3.0" Stone Base + 13.8" Chamber Height+ 6.0" Stone Cover= 1.90' Field Height 121 Chambers x 3.3 cf=403.8 cf Chamber Storage 121 Chambers x 3.7 cf=448.7 cf Displacement 1,073.5 cf Field-448.7 cf Chambers= 624.9 cf Stone x 40.0%Voids = 249.9 cf Stone Storage Chamber Storage + Stone Storage= 653.7 cf= 0.015 of Overall Storage Efficiency = 60.9 Overall System Size = 25.65'x 22.04'x 1.90' 121 Chambers 39.8 cy Field 23.1 cy Stone 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 14 Summary for Pond TD104: TD104 nflow Area = 0.202 ac, 86.99% Impervious, Inflow Depth = 2.41" for 2-yr event Inflow = 0.50 cfs @ 12.07 hrs, Volume= 0.041 of Primary = 0.50 cfs @ 12.07 hrs, Volume= 0.041 af, Atten= 0%, Lag= 0.0 min Routed to Link DP-A : Main Street Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs, 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 15 Summary for Link DP-A: Main Street Inflow Area = 0.213 ac, 87.18% Impervious, Inflow Depth = 2.42" for 2-yr event Inflow = 0.53 cfs @ 12.08 hrs, Volume= 0.043 of Primary = 0.53 cfs @ 12.08 hrs, Volume= 0.043 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs 149 Main St Proposed Conditions Type /// 24-hr 2-yr Rainfall=3.14" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 16 Summary for Link DP-B: Second Street Inflow Area = 0.480 ac, 93.15% Impervious, Inflow Depth = 1.94" for 2-yr event Inflow = 1.21 cfs @ 12.12 hrs, Volume= 0.078 of Primary = 1.21 cfs @ 12.12 hrs, Volume= 0.078 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 17 Time span=0.00-48.00 hrs, dt=0.04 hrs, 1201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA-1:SidewalkTo Main Street Runoff Area=473 sf 90.70% Impervious Runoff Depth=4.40" Flow Length=25' Slope=0.0150 '/' Tc=6.0 min CN=95 Runoff=0.05 cfs 0.004 of SubcatchmentA-2:SE Parking Lot Runoff Area=7,190 sf 84.06% Impervious Runoff Depth=4.07" Tc=6.0 min CN=92 Runoff=0.74 cfs 0.056 of SubcatchmentA-O: Offsite Runoff Area=1,618 sf 100.00% Impervious Runoff Depth=4.74" Tc=0.0 min CN=98 Runoff=0.21 cfs 0.015 of SubcatchmentB-1: Building Runoff Area=14,795 sf 100.00% Impervious Runoff Depth=4.74" Tc=6.0 min CN=98 Runoff=1.64 cfs 0.134 of SubcatchmentB-2: SW Parking Lot Runoff Area=2,461 sf 89.15% Impervious Runoff Depth=4.29" Flow Length=25' Slope=0.0150 '/' Tc=6.0 min CN=94 Runoff=0.26 cfs 0.020 of SubcatchmentB-3: NW Parking Lot Runoff Area=2,749 sf 60.97% Impervious Runoff Depth=3.25" Tc=6.0 min CN=84 Runoff=0.24 cfs 0.017 of SubcatchmentB-4: SidewalkTo Second Runoff Area=892 sf 89.69% Impervious Runoff Depth=4.29" Tc=6.0 min CN=94 Runoff=0.09 cfs 0.007 of Pond R: Infiltration System Peak Elev=98.26' Storage=1,646 cf Inflow=1.90 cfs 0.154 of Outflow=1.73 cfs 0.125 of Pond TD104:TD104 Inflow=0.86 cfs 0.071 of Primary=0.86 cfs 0.071 of Link DP-A: Main Street Inflow=0.91 cfs 0.075 of Primary=0.91 cfs 0.075 of Link DP-B: Second Street Inflow=2.04 cfs 0.150 of Primary=2.04 cfs 0.150 of Total Runoff Area = 0.693 ac Runoff Volume = 0.254 of Average Runoff Depth = 4.39" 8.69% Pervious = 0.060 ac 91.31% Impervious = 0.633 ac 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 18 Summary for Subcatchment A-1: Sidewalk To Main Street Runoff = 0.05 cfs @ 12.08 hrs, Volume= 0.004 af, Depth= 4.40" Routed to Link DP-A : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (sf) CN Description 429 98 Paved parking, HSG B 44 61 >75% Grass cover, Good, HSG B 473 95 Weighted Average 44 9.30% Pervious Area 429 90.70% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.4 25 0.0150 0.93 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.20" 0.4 25 Total, Increased to minimum Tc = 6.0 min 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 19 Summary for Subcatchment A-2: SE Parking Lot Runoff = 0.74 cfs @ 12.09 hrs, Volume= 0.056 af, Depth= 4.07" Routed to Pond TD 104 : TD 104 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (sf) CN Description 67044 98 Paved parking, HSG B 17146 61 >75% Grass cover, Good, HSG B 7,190 92 Weighted Average 17146 15.94% Pervious Area 67044 84.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 20 Summary for Subcatchment A-O: Offsite Runoff = 0.21 cfs @ 12.00 hrs, Volume= 0.015 af, Depth= 4.74" Routed to Pond TD 104 : TD 104 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (sf) CN Description 11618 98 Roofs, H S G 6 17618 100.00% Impervious Area 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 21 Summary for Subcatchment B-1: Building Runoff = 1.64 cfs @ 12.08 hrs, Volume= 0.134 af, Depth= 4.74" Routed to Pond R : Infiltration System Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (sf) CN Description 147795 98 Paved parking, HSG B 147795 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 22 Summary for Subcatchment B-2: SW Parking Lot Runoff = 0.26 cfs @ 12.08 hrs, Volume= 0.020 af, Depth= 4.29" Routed to Pond R : Infiltration System Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (sf) CN Description 27194 98 Paved parking, HSG B 267 61 >75% Grass cover, Good, HSG B 2461 94 Weighted Average 267 10.85% Pervious Area 2,194 89.15% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.4 25 0.0150 0.93 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.20" 0.4 25 Total, Increased to minimum Tc = 6.0 min 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 23 Summary for Subcatchment B-3: NW Parking Lot Runoff = 0.24 cfs @ 12.09 hrs, Volume= 0.017 af, Depth= 3.25" Routed to Link DP-B : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (sf) CN Description 17073 61 >75% Grass cover, Good, HSG B 1,676 98 Paved parking, HSG B 2749 84 Weighted Average 1,073 39.03% Pervious Area 1,676 60.97% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 24 Summary for Subcatchment B-4: Sidewalk To Second Street Runoff = 0.09 cfs @ 12.08 hrs, Volume= 0.007 af, Depth= 4.29" Routed to Link DP-B : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 10-yr Rainfall=4.98" Area (sf) CN Description 800 98 Paved parking, HSG B 92 61 >75% Grass cover, Good, HSG B 892 94 Weighted Average 92 10.31% Pervious Area 800 89.69% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type 11124-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 25 Summary for Pond R: Infiltration System Inflow Area = 0.396 ac, 98.45% Impervious, Inflow Depth = 4.68" for 10-yr event Inflow = 1.90 cfs @ 12.08 hrs, Volume= 0.154 of Outflow = 1.73 cfs @ 12.12 hrs, Volume= 0.125 af, Atten= 9%, Lag= 2.3 min Primary = 1.73 cfs @ 12.12 hrs, Volume= 0.125 of Routed to Link DP-B : Second Street Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 98.26' @ 12.12 hrs Surf.Area= 1,865 sf Storage= 1,646 cf Plug-Flow detention time= 143.4 min calculated for 0.125 of(81% of inflow) Center-of-Mass det. time=68.9 min ( 820.4 - 751.4 ) Volume Invert Avail.Storage Storage Description #1 A 97.00' 527 cf 54.85'W x 23.69'L x 1.90'H Field A 2,466 cf Overall - 1,149 cf Embedded = 1,317 cf x 40.0% Voids #2A 97.25' 1,035 cf ACF R-Tank XD 7 x 310 Inside #1 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 310 Chambers in 31 Rows #313 97.00' 250 cf 22.04'W x 25.65'L x 1.90'H Field B 1,074 cf Overall - 449 cf Embedded = 625 cf x 40.0% Voids #413 97.25' 404 cf ACF R-Tank XD 7 x 121 Inside #3 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 121 Chambers in 11 Rows 2,215 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary 96.83' 12.0" Round Culvert L= 22.0' CPP, square edge headwall, Ke= 0.500 Inlet/ Outlet Invert= 96.83'/ 96.49' S= 0.0155 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf #2 Device 1 98.00' 4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=1.72 cfs @ 12.12 hrs HW=98.26' (Free Discharge) L1=Culvert (Passes 1.72 cfs of 3.65 cfs potential flow) L2=Sharp-Crested Rectangular Weir(Weir Controls 1.72 cfs @ 1.67 fps) 149 Main St Proposed Conditions Type 11124-hr 10-yr Rainfall=4.98„ Prepared by Langan Engineering Printed 12/30/2022 HydroCAD01020-2f s/n 08223 02022 HvdroCAD Software Solutions LLC Page 26 Pond R: Infiltration System - Chamber Wizard Field A Chamber Model=ACF R-Tank XD 7 (ACF Environmental R-Tank XD) Inside= 19.7"W x 13.8"H => 1.70 sf x 1.971 = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.971 = 3.7 cf 10 Chambers/Row x 1.97' Long = 19.69' Row Length +24.0" End Stone x 2 = 23.69' Base Length 31 Rows x 19.7"Wide + 24.0" Side Stone x 2 = 54.85' Base Width 3.0" Stone Base + 13.8" Chamber Height+ 6.0" Stone Cover= 1.90' Field Height 310 Chambers x 3.3 cf= 1,034.5 cf Chamber Storage 310 Chambers x 3.7 cf= 1,149.5 cf Displacement 2,466.3 cf Field- 1,149.5 cf Chambers = 1,316.8 cf Stone x 40.0%Voids = 526.7 cf Stone Storage Chamber Storage + Stone Storage= 1,561.2 cf = 0.036 of Overall Storage Efficiency = 63.3 Overall System Size = 23.69'x 54.85' x 1.90' 310 Chambers 91.3 cy Field 48.8 cy Stone 149 Main St Proposed Conditions Type 11124-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD01020-2f s/n 08223 02022 HvdroCAD Software Solutions LLC Page 27 Pond R: Infiltration System - Chamber Wizard Field B Chamber Model=ACF R-Tank XD 7 (ACF Environmental R-Tank XD) Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L= 3.7 cf 11 Chambers/Row x 1.97' Long = 21.65' Row Length +24.0" End Stone x 2 = 25.65' Base Length 11 Rows x 19.7"Wide + 24.0" Side Stone x 2 = 22.04' Base Width 3.0" Stone Base + 13.8" Chamber Height+ 6.0" Stone Cover= 1.90' Field Height 121 Chambers x 3.3 cf=403.8 cf Chamber Storage 121 Chambers x 3.7 cf=448.7 cf Displacement 1,073.5 cf Field-448.7 cf Chambers= 624.9 cf Stone x 40.0%Voids = 249.9 cf Stone Storage Chamber Storage + Stone Storage= 653.7 cf= 0.015 of Overall Storage Efficiency = 60.9 Overall System Size = 25.65'x 22.04'x 1.90' 121 Chambers 39.8 cy Field 23.1 cy Stone 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 28 Summary for Pond TD104: TD104 Inflow Area = 0.202 ac, 86.99% Impervious, Inflow Depth = 4.19" for 10-yr event Inflow = 0.86 cfs @ 12.07 hrs, Volume= 0.071 of Primary = 0.86 cfs @ 12.07 hrs, Volume= 0.071 af, Atten= 0%, Lag= 0.0 min Routed to Link DP-A : Main Street Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs, 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 29 Summary for Link DP-A: Main Street Inflow Area = 0.213 ac, 87.18% Impervious, Inflow Depth = 4.20" for 10-yr event Inflow = 0.91 cfs @ 12.07 hrs, Volume= 0.075 of Primary = 0.91 cfs @ 12.07 hrs, Volume= 0.075 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs 149 Main St Proposed Conditions Type /// 24-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 30 Summary for Link DP-B: Second Street Inflow Area = 0.480 ac, 93.15% Impervious, Inflow Depth = 3.75" for 10-yr event Inflow = 2.04 cfs @ 12.12 hrs, Volume= 0.150 of Primary = 2.04 cfs @ 12.12 hrs, Volume= 0.150 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 31 Time span=0.00-48.00 hrs, dt=0.04 hrs, 1201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA-1:SidewalkTo Main Street Runoff Area=473 sf 90.70% Impervious Runoff Depth=5.54" Flow Length=25' Slope=0.0150 '/' Tc=6.0 min CN=95 Runoff=0.06 cfs 0.005 of SubcatchmentA-2:SE Parking Lot Runoff Area=7,190 sf 84.06% Impervious Runoff Depth=5.20" Tc=6.0 min CN=92 Runoff=0.93 cfs 0.071 of SubcatchmentA-O: Offsite Runoff Area=1,618 sf 100.00% Impervious Runoff Depth=5.89" Tc=0.0 min CN=98 Runoff=0.26 cfs 0.018 of SubcatchmentB-1: Building Runoff Area=14,795 sf 100.00% Impervious Runoff Depth=5.89" Tc=6.0 min CN=98 Runoff=2.02 cfs 0.167 of SubcatchmentB-2: SW Parking Lot Runoff Area=2,461 sf 89.15% Impervious Runoff Depth=5.43" Flow Length=25' Slope=0.0150 '/' Tc=6.0 min CN=94 Runoff=0.33 cfs 0.026 of SubcatchmentB-3: NW Parking Lot Runoff Area=2,749 sf 60.97% Impervious Runoff Depth=4.32" Tc=6.0 min CN=84 Runoff=0.31 cfs 0.023 of SubcatchmentB-4: SidewalkTo Second Runoff Area=892 sf 89.69% Impervious Runoff Depth=5.43" Tc=6.0 min CN=94 Runoff=0.12 cfs 0.009 of Pond R: Infiltration System Peak Elev=98.30' Storage=1,706 cf Inflow=2.35 cfs 0.192 of Outflow=2.16 cfs 0.163 of Pond TD104:TD104 Inflow=1.08 cfs 0.090 of Primary=1.08 cfs 0.090 of Link DP-A: Main Street Inflow=1.14 cfs 0.095 of Primary=1.14 cfs 0.095 of Link DP-B: Second Street Inflow=2.56 cfs 0.195 of Primary=2.56 cfs 0.195 of Total Runoff Area = 0.693 ac Runoff Volume = 0.319 of Average Runoff Depth = 5.53" 8.69% Pervious = 0.060 ac 91.31% Impervious = 0.633 ac 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 32 Summary for Subcatchment A-1: Sidewalk To Main Street Runoff = 0.06 cfs @ 12.08 hrs, Volume= 0.005 af, Depth= 5.54" Routed to Link DP-A : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (sf) CN Description 429 98 Paved parking, HSG B 44 61 >75% Grass cover, Good, HSG B 473 95 Weighted Average 44 9.30% Pervious Area 429 90.70% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.4 25 0.0150 0.93 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.20" 0.4 25 Total, Increased to minimum Tc = 6.0 min 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 33 Summary for Subcatchment A-2: SE Parking Lot Runoff = 0.93 cfs @ 12.09 hrs, Volume= 0.071 af, Depth= 5.20" Routed to Pond TD 104 : TD 104 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (sf) CN Description 67044 98 Paved parking, HSG B 17146 61 >75% Grass cover, Good, HSG B 7,190 92 Weighted Average 17146 15.94% Pervious Area 67044 84.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 34 Summary for Subcatchment A-O: Offsite Runoff = 0.26 cfs @ 12.00 hrs, Volume= 0.018 af, Depth= 5.89" Routed to Pond TD 104 : TD 104 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (sf) CN Description 11618 98 Roofs, H S G 6 17618 100.00% Impervious Area 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 35 Summary for Subcatchment B-1: Building Runoff = 2.02 cfs @ 12.08 hrs, Volume= 0.167 af, Depth= 5.89" Routed to Pond R : Infiltration System Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (sf) CN Description 147795 98 Paved parking, HSG B 147795 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 36 Summary for Subcatchment B-2: SW Parking Lot Runoff = 0.33 cfs @ 12.08 hrs, Volume= 0.026 af, Depth= 5.43" Routed to Pond R : Infiltration System Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (sf) CN Description 27194 98 Paved parking, HSG B 267 61 >75% Grass cover, Good, HSG B 2461 94 Weighted Average 267 10.85% Pervious Area 2,194 89.15% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.4 25 0.0150 0.93 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.20" 0.4 25 Total, Increased to minimum Tc = 6.0 min 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 37 Summary for Subcatchment B-3: NW Parking Lot Runoff = 0.31 cfs @ 12.09 hrs, Volume= 0.023 af, Depth= 4.32" Routed to Link DP-B : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (sf) CN Description 17073 61 >75% Grass cover, Good, HSG B 1,676 98 Paved parking, HSG B 2749 84 Weighted Average 1,073 39.03% Pervious Area 1,676 60.97% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 38 Summary for Subcatchment B-4: Sidewalk To Second Street Runoff = 0.12 cfs @ 12.08 hrs, Volume= 0.009 af, Depth= 5.43" Routed to Link DP-B : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 25-yr Rainfall=6.13" Area (sf) CN Description 800 98 Paved parking, HSG B 92 61 >75% Grass cover, Good, HSG B 892 94 Weighted Average 92 10.31% Pervious Area 800 89.69% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type 11124-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 39 Summary for Pond R: Infiltration System Inflow Area = 0.396 ac, 98.45% Impervious, Inflow Depth = 5.83" for 25-yr event Inflow = 2.35 cfs @ 12.08 hrs, Volume= 0.192 of Outflow = 2.16 cfs @ 12.12 hrs, Volume= 0.163 af, Atten= 8%, Lag= 2.2 min Primary = 2.16 cfs @ 12.12 hrs, Volume= 0.163 of Routed to Link DP-B : Second Street Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 98.30' @ 12.12 hrs Surf.Area= 1,865 sf Storage= 1,706 cf Plug-Flow detention time= 127.3 min calculated for 0.163 of(85% of inflow) Center-of-Mass det. time=62.2 min ( 810.1 - 747.9 ) Volume Invert Avail.Storage Storage Description #1 A 97.00' 527 cf 54.85'W x 23.69'L x 1.90'H Field A 2,466 cf Overall - 1,149 cf Embedded = 1,317 cf x 40.0% Voids #2A 97.25' 1,035 cf ACF R-Tank XD 7 x 310 Inside #1 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 310 Chambers in 31 Rows #313 97.00' 250 cf 22.04'W x 25.65'L x 1.90'H Field B 1,074 cf Overall - 449 cf Embedded = 625 cf x 40.0% Voids #413 97.25' 404 cf ACF R-Tank XD 7 x 121 Inside #3 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 121 Chambers in 11 Rows 2,215 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary 96.83' 12.0" Round Culvert L= 22.0' CPP, square edge headwall, Ke= 0.500 Inlet/ Outlet Invert= 96.83'/ 96.49' S= 0.0155 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf #2 Device 1 98.00' 4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=2.15 cfs @ 12.12 hrs HW=98.30' (Free Discharge) L1=Culvert (Passes 2.15 cfs of 3.73 cfs potential flow) L2=Sharp-Crested Rectangular Weir(Weir Controls 2.15 cfs @ 1.80 fps) 149 Main St Proposed Conditions Type 11124-hr 25-yr Rainfall=6.13„ Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 1020-2f s/n 08223 O 2022 HvdroCAD Software Solutions LLC Page 40 Pond R: Infiltration System - Chamber Wizard Field A Chamber Model=ACF R-Tank XD 7 (ACF Environmental R-Tank XD) Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L= 3.7 cf 10 Chambers/Row x 1.97' Long = 19.69' Row Length +24.0" End Stone x 2 = 23.69' Base Length 31 Rows x 19.7"Wide + 24.0" Side Stone x 2 = 54.85' Base Width 3.0" Stone Base + 13.8" Chamber Height+ 6.0" Stone Cover= 1.90' Field Height 310 Chambers x 3.3 cf= 1,034.5 cf Chamber Storage 310 Chambers x 3.7 cf= 1,149.5 cf Displacement 2,466.3 cf Field- 1,149.5 cf Chambers = 1,316.8 cf Stone x 40.0%Voids = 526.7 cf Stone Storage Chamber Storage + Stone Storage= 1,561.2 cf = 0.036 of Overall Storage Efficiency = 63.3 Overall System Size = 23.69'x 54.85' x 1.90' 310 Chambers 91.3 cy Field 48.8 cy Stone 149 Main St Proposed Conditions Type 11124-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 1020-2f s/n 08223 O 2022 HvdroCAD Software Solutions LLC Page 41 Pond R: Infiltration System - Chamber Wizard Field B Chamber Model=ACF R-Tank XD 7 (ACF Environmental R-Tank XD) Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L= 3.7 cf 11 Chambers/Row x 1.97' Long = 21.65' Row Length +24.0" End Stone x 2 = 25.65' Base Length 11 Rows x 19.7"Wide + 24.0" Side Stone x 2 = 22.04' Base Width 3.0" Stone Base + 13.8" Chamber Height+ 6.0" Stone Cover= 1.90' Field Height 121 Chambers x 3.3 cf=403.8 cf Chamber Storage 121 Chambers x 3.7 cf=448.7 cf Displacement 1,073.5 cf Field-448.7 cf Chambers= 624.9 cf Stone x 40.0%Voids = 249.9 cf Stone Storage Chamber Storage + Stone Storage= 653.7 cf= 0.015 of Overall Storage Efficiency = 60.9 Overall System Size = 25.65'x 22.04'x 1.90' 121 Chambers 39.8 cy Field 23.1 cy Stone 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 42 Summary for Pond TD104: TD104 nflow Area = 0.202 ac, 86.99% Impervious, Inflow Depth = 5.32" for 25-yr event Inflow = 1.08 cfs @ 12.07 hrs, Volume= 0.090 of Primary = 1.08 cfs @ 12.07 hrs, Volume= 0.090 af, Atten= 0%, Lag= 0.0 min Routed to Link DP-A : Main Street Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs, 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 43 Summary for Link DP-A: Main Street Inflow Area = 0.213 ac, 87.18% Impervious, Inflow Depth = 5.34" for 25-yr event Inflow = 1.14 cfs @ 12.07 hrs, Volume= 0.095 of Primary = 1.14 cfs @ 12.07 hrs, Volume= 0.095 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs 149 Main St Proposed Conditions Type /// 24-hr 25-yr Rainfall=6.13" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 44 Summary for Link DP-B: Second Street Inflow Area = 0.480 ac, 93.15% Impervious, Inflow Depth = 4.88" for 25-yr event Inflow = 2.56 cfs @ 12.12 hrs, Volume= 0.195 of Primary = 2.56 cfs @ 12.12 hrs, Volume= 0.195 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 45 Time span=0.00-48.00 hrs, dt=0.04 hrs, 1201 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentA-1:SidewalkTo Main Street Runoff Area=473 sf 90.70% Impervious Runoff Depth=8.20" Flow Length=25' Slope=0.0150 '/' Tc=6.0 min CN=95 Runoff=0.09 cfs 0.007 of SubcatchmentA-2:SE Parking Lot Runoff Area=7,190 sf 84.06% Impervious Runoff Depth=7.84" Tc=6.0 min CN=92 Runoff=1.37 cfs 0.108 of SubcatchmentA-O: Offsite Runoff Area=1,618 sf 100.00% Impervious Runoff Depth=8.56" Tc=0.0 min CN=98 Runoff=0.37 cfs 0.026 of SubcatchmentB-1: Building Runoff Area=14,795 sf 100.00% Impervious Runoff Depth=8.56" Tc=6.0 min CN=98 Runoff=2.91 cfs 0.242 of SubcatchmentB-2: SW Parking Lot Runoff Area=2,461 sf 89.15% Impervious Runoff Depth=8.08" Flow Length=25' Slope=0.0150 '/' Tc=6.0 min CN=94 Runoff=0.48 cfs 0.038 of SubcatchmentB-3: NW Parking Lot Runoff Area=2,749 sf 60.97% Impervious Runoff Depth=6.87" Tc=6.0 min CN=84 Runoff=0.48 cfs 0.036 of SubcatchmentB-4: SidewalkTo Second Runoff Area=892 sf 89.69% Impervious Runoff Depth=8.08" Tc=6.0 min CN=94 Runoff=0.17 cfs 0.014 of Pond R: Infiltration System Peak Elev=98.39' Storage=1,834 cf Inflow=3.39 cfs 0.280 of Outflow=3.15 cfs 0.251 of Pond TD104:TD104 Inflow=1.58 cfs 0.134 of Primary=1.58 cfs 0.134 of Link DP-A: Main Street Inflow=1.67 cfs 0.142 of Primary=1.67 cfs 0.142 of Link DP-B: Second Street Inflow=3.77 cfs 0.301 of Primary=3.77 cfs 0.301 of Total Runoff Area = 0.693 ac Runoff Volume = 0.472 of Average Runoff Depth = 8.17" 8.69% Pervious = 0.060 ac 91.31% Impervious = 0.633 ac 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 46 Summary for Subcatchment A-1: Sidewalk To Main Street Runoff = 0.09 cfs @ 12.08 hrs, Volume= 0.007 af, Depth= 8.20" Routed to Link DP-A : Main Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (sf) CN Description 429 98 Paved parking, HSG B 44 61 >75% Grass cover, Good, HSG B 473 95 Weighted Average 44 9.30% Pervious Area 429 90.70% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.4 25 0.0150 0.93 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.20" 0.4 25 Total, Increased to minimum Tc = 6.0 min 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 47 Summary for Subcatchment A-2: SE Parking Lot Runoff = 1.37 cfs @ 12.08 hrs, Volume= 0.108 af, Depth= 7.84" Routed to Pond TD 104 : TD 104 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (sf) CN Description 67044 98 Paved parking, HSG B 17146 61 >75% Grass cover, Good, HSG B 7,190 92 Weighted Average 17146 15.94% Pervious Area 67044 84.06% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 48 Summary for Subcatchment A-O: Offsite Runoff = 0.37 cfs @ 12.00 hrs, Volume= 0.026 af, Depth= 8.56" Routed to Pond TD 104 : TD 104 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (sf) CN Description 11618 98 Roofs, H S G 6 17618 100.00% Impervious Area 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 49 Summary for Subcatchment B-1: Building Runoff = 2.91 cfs @ 12.08 hrs, Volume= 0.242 af, Depth= 8.56" Routed to Pond R : Infiltration System Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (sf) CN Description 147795 98 Paved parking, HSG B 147795 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCADO 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 50 Summary for Subcatchment B-2: SW Parking Lot Runoff = 0.48 cfs @ 12.08 hrs, Volume= 0.038 af, Depth= 8.08" Routed to Pond R : Infiltration System Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (sf) CN Description 27194 98 Paved parking, HSG B 267 61 >75% Grass cover, Good, HSG B 2461 94 Weighted Average 267 10.85% Pervious Area 2,194 89.15% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.4 25 0.0150 0.93 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.20" 0.4 25 Total, Increased to minimum Tc = 6.0 min 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 51 Summary for Subcatchment B-3: NW Parking Lot Runoff = 0.48 cfs @ 12.09 hrs, Volume= 0.036 af, Depth= 6.87" Routed to Link DP-B : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (sf) CN Description 17073 61 >75% Grass cover, Good, HSG B 1,676 98 Paved parking, HSG B 2749 84 Weighted Average 1,073 39.03% Pervious Area 1,676 60.97% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 52 Summary for Subcatchment B-4: Sidewalk To Second Street Runoff = 0.17 cfs @ 12.08 hrs, Volume= 0.014 af, Depth= 8.08" Routed to Link DP-B : Second Street Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Type III 24-hr 100-yr Rainfall=8.80" Area (sf) CN Description 800 98 Paved parking, HSG B 92 61 >75% Grass cover, Good, HSG B 892 94 Weighted Average 92 10.31% Pervious Area 800 89.69% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 149 Main St Proposed Conditions Type 111 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 53 Summary for Pond R: Infiltration System Inflow Area = 0.396 ac, 98.45% Impervious, Inflow Depth = 8.49" for 100-yr event Inflow = 3.39 cfs @ 12.08 hrs, Volume= 0.280 of Outflow = 3.15 cfs @ 12.12 hrs, Volume= 0.251 af, Atten= 7%, Lag= 2.0 min Primary = 3.15 cfs @ 12.12 hrs, Volume= 0.251 of Routed to Link DP-B : Second Street Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 98.39' @ 12.12 hrs Surf.Area= 1,865 sf Storage= 1,834 cf Plug-Flow detention time= 102.5 min calculated for 0.251 of(90% of inflow) Center-of-Mass det. time= 51.3 min ( 794.0 - 742.7 ) Volume Invert Avail.Storage Storage Description #1 A 97.00' 527 cf 54.85'W x 23.69'L x 1.90'H Field A 2,466 cf Overall - 1,149 cf Embedded = 1,317 cf x 40.0% Voids #2A 97.25' 1,035 cf ACF R-Tank XD 7 x 310 Inside #1 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 310 Chambers in 31 Rows #313 97.00' 250 cf 22.04'W x 25.65'L x 1.90'H Field B 1,074 cf Overall - 449 cf Embedded = 625 cf x 40.0% Voids #413 97.25' 404 cf ACF R-Tank XD 7 x 121 Inside #3 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 121 Chambers in 11 Rows 2,215 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary 96.83' 12.0" Round Culvert L= 22.0' CPP, square edge headwall, Ke= 0.500 Inlet/ Outlet Invert= 96.83'/ 96.49' S= 0.0155 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf #2 Device 1 98.00' 4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=3.14 cfs @ 12.12 hrs HW=98.39' (Free Discharge) L1=Culvert (Passes 3.14 cfs of 3.90 cfs potential flow) L2=Sharp-Crested Rectangular Weir(Weir Controls 3.14 cfs @ 2.05 fps) 149 Main St Proposed Conditions Type 11124-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD01020-2f s/n 08223 02022 HvdroCAD Software Solutions LLC Page 54 Pond R: Infiltration System - Chamber Wizard Field A Chamber Model=ACF R-Tank XD 7 (ACF Environmental R-Tank XD) Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L= 3.7 cf 10 Chambers/Row x 1.97' Long = 19.69' Row Length +24.0" End Stone x 2 = 23.69' Base Length 31 Rows x 19.7"Wide + 24.0" Side Stone x 2 = 54.85' Base Width 3.0" Stone Base + 13.8" Chamber Height+ 6.0" Stone Cover= 1.90' Field Height 310 Chambers x 3.3 cf= 1,034.5 cf Chamber Storage 310 Chambers x 3.7 cf= 1,149.5 cf Displacement 2,466.3 cf Field- 1,149.5 cf Chambers = 1,316.8 cf Stone x 40.0%Voids = 526.7 cf Stone Storage Chamber Storage + Stone Storage= 1,561.2 cf = 0.036 of Overall Storage Efficiency = 63.3 Overall System Size = 23.69'x 54.85' x 1.90' 310 Chambers 91.3 cy Field 48.8 cy Stone 149 Main St Proposed Conditions Type 11124-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD01020-2f s/n 08223 02022 HvdroCAD Software Solutions LLC Page 55 Pond R: Infiltration System - Chamber Wizard Field B Chamber Model=ACF R-Tank XD 7 (ACF Environmental R-Tank XD) Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L= 3.7 cf 11 Chambers/Row x 1.97' Long = 21.65' Row Length +24.0" End Stone x 2 = 25.65' Base Length 11 Rows x 19.7"Wide + 24.0" Side Stone x 2 = 22.04' Base Width 3.0" Stone Base + 13.8" Chamber Height+ 6.0" Stone Cover= 1.90' Field Height 121 Chambers x 3.3 cf=403.8 cf Chamber Storage 121 Chambers x 3.7 cf=448.7 cf Displacement 1,073.5 cf Field-448.7 cf Chambers= 624.9 cf Stone x 40.0%Voids = 249.9 cf Stone Storage Chamber Storage + Stone Storage= 653.7 cf= 0.015 of Overall Storage Efficiency = 60.9 Overall System Size = 25.65'x 22.04'x 1.90' 121 Chambers 39.8 cy Field 23.1 cy Stone 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC P a q e 56 Summary for Pond TD104: TD104 Inflow Area = 0.202 ac, 86.99% Impervious, Inflow Depth = 7.97" for 100-yr event Inflow = 1.58 cfs @ 12.07 hrs, Volume= 0.134 of Primary = 1.58 cfs @ 12.07 hrs, Volume= 0.134 af, Atten= 0%, Lag= 0.0 min Routed to Link DP-A : Main Street Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs, 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 57 Summary for Link DP-A: Main Street Inflow Area = 0.213 ac, 87.18% Impervious, Inflow Depth = 7.98" for 100-yr event Inflow = 1.67 cfs @ 12.07 hrs, Volume= 0.142 of Primary = 1.67 cfs @ 12.07 hrs, Volume= 0.142 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs 149 Main St Proposed Conditions Type /// 24-hr 100-yr Rainfall=8.80" Prepared by Langan Engineering Printed 12/30/2022 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page CO Summary for Link DP-B: Second Street Inflow Area = 0.480 ac, 93.15% Impervious, Inflow Depth = 7.53" for 100-yr event Inflow = 3.77 cfs @ 12.11 hrs, Volume= 0.301 of Primary = 3.77 cfs @ 12.11 hrs, Volume= 0.301 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs APPENDIX C Stormwater Quality, Recharge, and Groundwater Mounding Calculations LA/VEA/V Standard 3: Recharge Total Impervious Coverage 25,938 sf 0.595 ac Impervious Coverage HSG-A 0 sf 0.00 ac Impervious Coverage HSG-B 25,938 sf 0.595 ac Impervious Coverage HSG-C 0 sf 0.00 ac Impervious Coverage HSG-D 0 sf 0.00 ac Total Impervious Site Area Draining to Recharge Facilities 0.390 ac Site Impervious Area Draining to Recharge Facilities 65% Recharge Adjustment=Site Impervious/Imp Draining to Recharge Facilities= 1.53 HSG F (in) Aimp(sf) Rv(cf) A 0.60 0 0 B 0.35 25,938 757 C 0.25 0 0 D 0.10 0 0 Total Required Recharge Volume, Rv 757 Adjusted Total Required Recharge 11155 Total Recharge Volume Provided 1,268 1 149 Main St Proposed Conditions Type 11124-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 2/14/2023 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 1 Summary for Pond R: Infiltration System Inflow Area = 0.396 ac, 98.45% Impervious, Inflow Depth = 4.68" for 10-yr event Inflow = 1.90 cfs @ 12.08 hrs, Volume= 0.154 of Outflow = 1.73 cfs @ 12.12 hrs, Volume= 0.125 af, Atten= 9%, Lag= 2.3 min Primary = 1.73 cfs @ 12.12 hrs, Volume= 0.125 of Routed to Link DP-B : Second Street Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.04 hrs Peak Elev= 98.26' @ 12.12 hrs Surf.Area= 1,865 sf Storage= 1,646 cf Plug-Flow detention time= 143.4 min calculated for 0.125 of(81% of inflow) Center-of-Mass det. time=68.9 min ( 820.4 - 751.4 ) Volume Invert Avail.Storage Storage Description #1 A 97.00' 527 cf 54.85'W x 23.69'L x 1.90'H Field A 2,466 cf Overall - 1,149 cf Embedded = 1,317 cf x 40.0% Voids #2A 97.25' 1,035 cf ACF R-Tank XD 7 x 310 Inside #1 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 310 Chambers in 31 Rows #313 97.00' 250 cf 22.04'W x 25.65'L x 1.90'H Field B 1,074 cf Overall - 449 cf Embedded = 625 cf x 40.0% Voids #413 97.25' 404 cf ACF R-Tank XD 7 x 121 Inside #3 Inside= 19.7"W x 13.8"H => 1.70 sf x 1.97'L = 3.3 cf Outside= 19.7"W x 13.8"H => 1.88 sf x 1.97'L = 3.7 cf 121 Chambers in 11 Rows 2,215 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber Wizard Device Routing Invert Outlet Devices #1 Primary 96.83' 12.0" Round Culvert L= 22.0' CPP, square edge headwall, Ke= 0.500 Inlet/ Outlet Invert= 96.83'/ 96.49' S= 0.0155 '/' Cc= 0.900 n= 0.013, Flow Area= 0.79 sf #2 Device 1 98.00' 4.0' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Primary OutFlow Max=1.72 cfs @ 12.12 hrs HW=98.26' (Free Discharge) L1=Culvert (Passes 1.72 cfs of 3.65 cfs potential flow) L2=Sharp-Crested Rectangular Weir(Weir Controls 1.72 cfs @ 1.67 fps) 149 Main St Proposed Conditions Type 11124-hr 10-yr Rainfall=4.98" Prepared by Langan Engineering Printed 2/14/2023 HydroCAD® 10.20-2f s/n 08223 ©2022 HydroCAD Software Solutions LLC Page 2 Stage-Area-Storage for Pond R: Infiltration System Elevation Storage Elevation Storage (feet) (cubic-feet) (feet) (cubic-feet) 97.00 0 98.02 13297 97.02 15 98.04 19325 97.04 30 98.06 13354 97.06 45 98.08 1)383 97.08 60 98.10 1,412 97.10 75 98.12 1,441 97.12 90 98.14 1,470 97.14 104 98.16 1,498 97.16 119 98.18 1,527 97.18 134 98.20 1,556 97.20 149 98.22 13585 97.22 164 98.24 13614 97.24 179 98.26 11643 97.26 201 98.28 1,671 97.28 230 98.30 1,700 97.30 259 98.32 1,729 97.32 287 98.34 1,758 97.34 316 98.36 1,787 97.36 345 98.38 1,816 97.38 374 98.40 1,843 97.40 403 98.42 13858 97.42 432 98.44 13873 97.44 460 98.46 19888 97.46 489 98.48 13903 97.48 518 98.50 1,918 97.50 547 98.52 1,933 97.52 576 98.54 1,948 97.54 605 98.56 1,963 97.56 633 98.58 1,978 97.58 662 98.60 1,993 97.60 691 98.62 2,007 97.62 720 98.64 23022 97.64 749 98.66 23037 97.66 778 98.68 21052 97.68 806 98.70 2,067 97.70 835 98.72 2,082 97.72 864 98.74 2,097 97.74 893 98.76 2,112 97.76 922 98.78 2,127 97.78 951 98.80 2,142 97.80 979 98.82 2,157 97.82 15008 98.84 23172 97.84 13037 98.86 23186 97.86 13066 98.88 29201 97.88 13095 98.90 29215 97.90 13124 97.92 1,152 97.94 1,181 97.96 1,210 97.98 1,239 98.00 11268 Standard 3: 72-hour Drawdown Analysis 'Table,,2.3.3. 1982, Rawls Rates's Texture Class NRCS Hy&-ologic Soll Group Infiltration Rate (HSG) Inches/Haur 8_ 7 Sand A 2 r Loamy'�Sand A 2-4.1 Sandy,L,,,owu B 1-02, Loam B 0-52 0_ 7 Silt Loam C 2 r Sandy,Clay Loam C 0-17 Clay Lomn D, 0-09 S,11q,Clay Loani D 0-06 Sandy,Clay D, 0-05 S,11q,Clay D, 0-0114 'C,,,Iay D, 0-02 Table 2.3.3 from Massachusetts Stormwater Handbook;Volume 3,pg.22 Drawdown Time Rv where: Rv=Storage Volume Below Outlet [Ac-ft] (K) (Bottom Area) K= Infiltration Rate [in/hr] Bottom Area= Bottom Area of Recharge System [Ac] Infiltration System Rv= 0.029 Ac-ft K= 1.020 in/hr Bottom Area = 0.043 Acres Drawdown Time= 8.0 Hours <72 Hours, Design is in compliance with the standard. This spreadsheet will calculate the height of a groundwater mound beneath a stormwater infiltration basin. More information can be found in the U.S.Geological Survey Scientific Investigations Report 2010-5102"Simulation of groundwater mounding beneath hypothetical stormwater infiltration basins". The user must specify infiltration rate(R),specific yield(Sy),horizontal hydraulic conductivity(Kh), basin dimensions(x,y),duration of infiltration period(t),and the initial thickness of the saturated zone(hi(0),height of the water table if the bottom of the aquifer is the datum). For a square basin the half width equals the half length(x=y). For a rectangular basin,if the user wants the water-table changes perpendicular to the long side,specify x as the short dimension and y as the long dimension. Conversely, if the user wants the values perpendicular to the short side,specify y as the short dimension,x as the long dimension. All distances are from the center of the basin. Users can change the distances from the center of the basin at which water-table aquifer thickness are calculated. Cells highlighted in yellow are values that can be changed by the user. Cells highlighted in red are output values based on user-specified inputs.The user MUST click the blue"Re-Calculate ow"button each time ANY of the user-specified inputs are changed otherwise necessary iterations to converge on the correct solution will not be done and values shown will be incorrect. Use consistent units for all input values(for example,feet and days) use consistent units(e.g.feet&days or inches&hours) Conversion Table Input Values inch/hour feet/day 0.2300 R Recharge(infiltration)rate(feet/day) 0.67 1.33 0.210 Sy Specific yield,Sy(dimensionless,between 0 and 1) 20.40 K Horizontal hydraulic conductivity,Kh (feet/day)* 2.00 4.00 In the report accompanying this spreadsheet 40.000 x 1/2 length of basin(x direction,in feet) (USGS SIR 2010-5102),vertical soil permeability 12.000 y 1/2 width of basin(y direction,in feet) hours days (ft/d)is assumed to be one-tenth horizontal 0.330 t duration of infiltration period(days) 36 1.50 hydraulic conductivity(ft/d). 23.500 hi(0) initial thickness of saturated zone(feet) h(max) maximum thickness of saturated zone(beneath center of basin at end of infiltration period) Oh(max) maximum groundwater mounding(beneath center of basin at end of infiltration period) Ground- Distance from water center of basin Mounding,in in x direction,in feet feet 0 Re-Calculate Now 20 40 50 60 Groundwater Mounding, in feet 70 0.140 $0 90 0.100 "iiiiiiiiiiiiiigpu 100 120 0.080 ��� 0.060 ........................................................................................................................................................................................................................................................................................................................................................................................................................................................... �mll 0.040 ............................................................................................................................................................. 0.020 .....................................................................................................................................................................................................uum 0.000 0 20 40 60 80 100 120 140 Disclaimer This spreadsheet solving the Hantush (1967) equation for ground-water mounding beneath an infiltration basin is made available to the general public as a convenience for those wishing to replicate values documented in the USGS Scientific Investigations Report 2010-5102 "Groundwater mounding beneath hypothetical stormwater infiltration basins" or to calculate values based on user-specified site conditions. Any changes made to the spreadsheet (other than values identified as user-specified) after transmission from the USGS could have unintended, undesirable consequences. These consequences could include, but may not be limited to: erroneous output, numerical instabilities, and violations of underlying assumptions that are inherent in results presented in the accompanying USGS published report. The USGS assumes no responsibility for the consequences of any changes made to the spreadsheet. If changes are made to the spreadsheet, the user is responsible for documenting the changes and justifying the results and conclusions. • • . , • 0 . L A IV Project Name: 149 Main Street Project Number: 151028501 0 Location: North Andover,MA Date: 2/8/2023 Computed By: HH HANTUSH INPUTS SW BMP Location& Storage Bottom Recharge Vertical Specific Horizontal 1/2 Length 1/2 Width Drawdown Drawdown Initial Thickness Drawdown Description Volume1 Surface Area Rate Permeability Yield Hydraulic of BMP of BMP Times Times of Saturated Time<72 hrs Rate Conductivity4 Zone (Rawls Rate) (cf) (sf) (ft/day) (in/hr) (feet/day) (ft) (ft) (hrs) (days) (feet) 1,268 1,864 0.23 1.02 0.21 20.40 40 12 8 0.33 23.50 YES GROUNDWATER MOUNDING RESULTS Infiltration/Detention Max GW Groundwater Reference BMP Bottom Top Elev.of Is Top Elev.Of System Mounding Elevation? Boring Elev. Mounding Mounding Less Than BMP Bottom Elevation? (ft) (ft) (ft) (ft) 0.131 95.04 LB-03 97.00 95.17 YES Notes: 1.Storage Volume based on static recharge volume 2.Recharge Rate= (Storage Volume/Bottom Surface Infiltration Area)/3 days 3.Specific Yield for fine sand=0.21 4.Horizontal Hydraulic Conductivity=Rawls Rate x 24 hours/day x 1 ft/12 inches x 10 5.Drawdown Time =Storage Volume/(Bottom Surface Infiltration Area x Rawls Rate) 6.Initial Thickness of Saturated Zone=Depth of Boring-Depth of Groundwater 7.Estimated seasonal high water table Stormwater Quality Calculations Calculation Design Guideline Stormwater Quality Volume(WQV) Massachusetts Stormwater Handbook/MS4 Watershed Stormwater Quality Flow(WQF) MassDEP& Ubran Hydrology for Small Watersheds TR-55 Proposed Watershed A-2 Watershed Characteristics Total Watershed Area 0.17 ac Impervious Area,Aimp 0.14 ac >>> 0.0002 mil Time of Concentration , TC 6 min >>> 0.1 hr Water Quality Volume(WQV) WQV= (QWQv)*(Aimp) Water Quality Depth, QwQv 0.5 in Impervious Area,Aimp 0.14 ac Water Quality Volume,WQV 0.01 ac-ft >>> 252 ft3 Water Quality Flow(WQF) WQF= (qu)*(Ajmp)*(QwQv) qu= Unit Peak Discharge (csm/in) A=drainage area (mil) Water Quality Depth, QwQv 0.5 in CN = 98 Tc= 0.100 hr la= 0.041 P= 1.2 in la/P= 0.034 Unit Peak Discharge, qu 752 csm/in Determine qu, using MassDEP Standard Method to Convert Required Water Quality Volume to a Water Quality Flow,WQF= 0.08 cfs Discharge Rate for Sizing Flow Based Manufactured Proprietary Stormwater Treatment Practices Figure 3 or 4 for la/P=0.034 for 1"QwQv 406&424 MIDDLESEX RD TYNGSBOROUGH, MA BY ARK DATE 11/17/2022 PROJ NO. 151028501 REV DATE SHEET 1 Stormwater Quality Calculations Calculation Design Guideline Stormwater Quality Volume (WQV) Massachusetts Stormwater Handbook/MS4 Watershed Stormwater Quality Flow(WQF) MassDEP& Urban Hydrology for Small Watersheds TR-55 Proposed Watershed B-2 Watershed Characteristics Total Watershed Area 0.06 ac Impervious Area,Aimp 0.05 ac >>> 0.0001 mil Time of Concentration , TC 6 min >>> 0.1 hr Water Quality Volume(WQV) WQV= (QwQv)*(Aimp) Water Quality Depth, QwQv 0.5 in Impervious Area,Aimp 0.05 ac Water Quality Volume,WQV 0.00 ac-ft »> 91 ft 3 Water Quality Flow(WQF) WQF = (qu)*(Aimp)*(QwQv) qu= Unit Peak Discharge(csm/in) A=drainage area (mil) Water Quality Depth, QwQv 0.5 in CN = 98 Tc= 0.100 hr la = 0.041 P = 1.2 in la/P = 0.034 Unit Peak Discharge, qu 752 csm/in Determine qu, using MassDEP Standard Method to Convert Required Water Quality Volume to a Water Quality Flow,WQF= 0.04 cfs Discharge Rate for Sizing Flow Based Manufactured Proprietary Stormwater Treatment Practices Figure 3 or 4 for la/P =0.034 for 1"QwQv 406&424 MIDDLESEX RD TYNGSBOROUGH, MA BY ARK DATE 12/29/2022 PROJ NO. 151028501 1 REV DATE SHEET 3 Stormwater Quality Calculations Calculation Design Guideline Stormwater Quality Volume(WQV) Massachusetts Stormwater Handbook/MS4 Watershed Stormwater Quality Flow(WQF) MassDEP& Ubran Hydrology for Small Watersheds TR-55 Proposed Watershed B-3 Watershed Characteristics Total Watershed Area 0.06 ac Impervious Area,Aimp 0.04 ac >>> 0.0001 mil Time of Concentration , TC 6 min >>> 0.1 hr Water Quality Volume(WQV) WQV= (QWQv)*(Aimp) Water Quality Depth, QwQv 0.5 in Impervious Area,Aimp 0.04 ac Water Quality Volume,WQV 0.00 ac-ft >>> 69 ft3 Water Quality Flow(WQF) WQF= (qu)*(Ajmp)*(QwQv) qu= Unit Peak Discharge (csm/in) A=drainage area (mil) Water Quality Depth, QwQv 0.5 in CN = 98 Tc= 0.100 hr la= 0.041 P= 1.2 in la/P= 0.034 Unit Peak Discharge, qu 752 csm/in Determine qu, using MassDEP Standard Method to Convert Required Water Quality Volume to a Water Quality Flow,WQF= 0.04 cfs Discharge Rate for Sizing Flow Based Manufactured Proprietary Stormwater Treatment Practices Figure 3 or 4 for la/P=0.034 for 1"QwQv 406&424 MIDDLESEX RD TYNGSBOROUGH, MA BY ARK DATE 10/20/2022 PROJ NO. 151028501 REV DATE SHEET 2 Illuuuuumuu�uuu i �������������������IIIIIIIIIIIIIll'ti��ll:)w ��������������������ll,all'Iltes llII a uIIVluuuuuVl 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Capacity' (c ) (CIII,,,,,,) (c ) (CIII,,,,,,) CS,,,,,,,4 2,.00 19 2000 2.80 2 C ,,,,,,,8 12.00 9000 14.00 130 �������l��11��l "I'l""I'll""I'll'll""I'll""I'll",'ll""I'll""I'll'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""I'll""I'll""I'll",'ll""I'll""I'll",'ll""I'll""I'l'll""I'll""Ill,� '11000 17.5 151 ............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. ModeIII ...Fireatirneint lRat e it iirn iir t C Il cit (c ) (CIII,,,,,) IIIIIIIIIIIII� II1 Illuuulul� '�'I uuuuul i������������������� 2015,,,,,, 1.40 25 ModeIII ,,,,,III,,,,,r tinn nt I t i men Capacity' 2 15,,,,,,5 1. 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............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. 2020,,,,,, 2.2 S.....III.....C 2400 1.58 205 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............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. 2 2 5,,,,,..5 3.2 ,,,,,III,,,,C 4800 2. 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III C,,,,,,,2 .,,,,,, 839 ............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................ 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iiiiiiiiiiiiiiiiiiiiiillillillillillillilliillillillillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillillillillillillilliillillillillillillilliillillilillillillillillillilillillillI ............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. 35,,,,,,E 6.50 ............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................. 4030,,,,,, 7.50 151 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1 Additional sediment storage capacity available-Check with your local representative for information. 2 Treatment Capacity is based on laboratory testing using OK-170(average D50 particle size of approximately 100 microns)and a 2400 micron screen. 3 Maintenance recommended when sediment depth has accumulated to within 12-18 inches of the dry weather water surface elevation. iiiiiiiiiiiiiiiiiiiiiillillillillillillilliillillilliillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilliillillillillillillillilliillillillillillillilliillillillillillillillillillilI 11�` iiiiiiiiiiiiiiiiiiiiiillillillillillillilliillillilillillilliIP uu uu i i uu uu, �r "%W0`0%W0%W001%00ft%00V iiiiiiiiiiiiiiiiiiiiiillillillillillillilliillillilliililillllI mill 00 i ���" NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS A WARRANTY.APPLICATIONS �.' 1"'NTECH'�' SUGGESTED HEREIN ARE DESCRIBED ONLY TO HELP READERS MAKE THEIR OWN EVALUATIONS "me'µ' " IIIINV AND DECISIONS,AND ARE NEITHER GUARANTEES NOR WARRANTIES OF SUITABILITY FOR ANY ENGINEERED SOLUTIONS APPLICATION.CONTECH MAKES NO WARRANTY WHATSOEVER,EXPRESS OR IMPLIED,RELATED TO THE APPLICATIONS,MATERIALS,COATINGS,OR PRODUCTS DISCUSSED HEREIN.ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND ALL IMPLIED WARRANTIES OF FITNESS FOR ANY Get social with us: 91 Im C]0 PARTICULAR PURPOSE ARE DISCLAIMED BY CONTECH.SEE CONTECH'S CONDITIONS OF SALE (AVAILABLE AT WWW.CONTECHES.COM/COS)FOR MORE INFORMATION. 800-338-1122� wlll'IIII' lllllli. III"' Q 2020 Contech Engineered Solutions LLC,a QUIKRETE Company All Rights Reserved.Printed in the USA.) Revision 08/20 N CONCRETE CURB. O O SIDEWALK. O J (D 41 U— CONCRETE TRENCH DRAIN. (SHOWN) ° a a PAVEMENT. a ° �� J oa a ° OUTLET. o 0 0 0° ° \\ 0 0 0°0 ..4 RUBBER GASKET ° MATERIAL. EARTH. OUTLET ADAPTOR & BYPASS WEIR. \ a. o a a ° REMOVABLE CAP FILTER ELEMENT SHEATHED IN GEOTEXTILE FOR PERIODIC // / SLEEVE. MAINTENANCE. FOSSIL ROCKTm ABSORBENT POUCHES. NOTES: 1. Filter insert shall have a high flow bypass feature. 2. Filter outlet adapter shall be constructed from stainless steel Type 304. Alternate outlet adaptor for shallow installations shall be PVC SCH-40. See detail B, sheet 2 of 2. 3. Filter medium shall be Fossil Rock TM, installed and maintained in accordance with manufacturer specifications. 4. Storage capacity reflects 80% of maximum solids collection prior to impeding filtering bypass. 5. For alternate outlet adapter configurations used for extremely shallow trench drains contact Oldcastle Stormwater Solutions for engineering assistance. 6. Filter element should be a minimum of one half the length of trench. Confirm flow rate upon order. FloGardl'-� Oldcastleo Stormwater Solutions Catch Basin Insert Filter 7921 Southpark Plaza,Suite 200 1 Littleton,CO 180120 1 Ph:800.579.8819 oldcastlestormwater.com THIS DOCUMENT IS THE PROPERTY OF OLDCASTLE PRECAST,INC.IT IS SUBMITTED FOR REFERENCE PURPOSES ONLY AND SHALL NOT BE USED IN ANYWAY INJURIOUS TO THE INTERESTS OF SAID COMPANY.COPYRIGHT©2010 OLDCASTLE PRECAST,INC.ALL RIGHTS RESERVED. Inlet DRAWING NO. REV ECO ECO-0142 DATE Filtration Trench Drain Style FG-LP-0002 H JPR 7 13 16 JPR 2/21/07 SHEET 1 OF 2 cv OUTLET GALLERY. 0 a a ° 0 o OUTLET ADAPTER & BYPASS WEIR. ° a � a a a ° a BYPASS FLOW OUTLET FILTER ELEMENT FILTERED FLOW WITH GEOTEXTILE SLEEVE. R7a ° ° Q ° DETAIL A a SECTION VIEW BYPASS PVC TEE. SCALE: 1 X ° a a 0 a a BYPASS FLOW ° FILTER ELEMENT FILTERED FLOW WITH G EOTEXTI LE SLEEVE. DETAIL B SECTION VIEW ALTERNATE ADAPTER CONFIGURATION SCALE: 1 X SPECIFIER CHART MINIMUM SOLIDS FILTERED TOTAL TRENCH TRENCH STORAGE FLOW BYPASS MODEL FILTER WIDTH "ID" DEPTH CAPACITY CUBIC FEET CAPACITY TYPE (FROM BOTTOM (CLEAR OPENING) OF GRATE) CUBIC FEET /SECOND CUBIC FEET ** ** /SECOND FG-TDOF3 PIPE* 3.0 6.5 0.1 0.5 0.1 FG-TDOF4 PIPE* 4.0 6.5 0.2 0.5 0.1 FG-TDOF6 PIPE 6.0 6.5 0.4 0.5 0.2 FG-TDOF8 PIPE 8.0 6.5 0.7 0.5 0.3 FG-TDOF10 PIPE 10.0 6.5 0.9 0.5 0.5 FG-TDOF12 PIPE 12.0 6.5 0.9 1.0 0.6 FG-TDOF18 PIPE 18.0 6.5 1.3 1.5 1.1 FG-TDOF24 PIPE 24.0 6.5 1.8 2.0 1.5 FG-TDOA6 PANEL 6.0 4.5 0.4 0.2 0.2 FG-TDOA8 PANEL 8.0 4.5 0.7 0.2 0.3 FG-TDOA10 PANEL 10.0 4.5 0.8 0.3 0.5 FG-TDOAl2 PANEL 12.0 4.5 1.0 0.4 0.6 FG-TDOA18 PANEL 18.0 4.5 1.4 0.8 1.1 FG-TDOA24 PANEL 24.0 4.5 1.8 1.1 1.5 *ALTERNATE ADAPTER CONFIGURATION. SEE DETAIL B. **CAPACITY PER 5-FT. SEGMENT USED. FloGard@ Oldcastleo Stormwater Solutions 7921 Southpark Plaza,Suite 200 1 Littleton,CO 1 80120 I Ph:800.579.8819 oldcastlestormwater.com Catch Basin Insert Filter THIS DOCUMENT IS THE PROPERTY OF OLDCASTLE PRECAST,INC.IT IS SUBMITTED FOR REFERENCE PURPOSES ONLY AND SHALL NOT BE USED IN ANYWAY INJURIOUS TO THE INTERESTS OF SAID COMPANY.COPYRIGHT©2010 OLDCASTLE PRECAST,INC.ALL RIGHTS RESERVED. Inlet DRAWING NO. REV ECO ECO-0142 DATE Filtration Trench Drain Style FG-LP-0002 H JPR 7 13 16 JPR 2/21/07 SHEET 2 OF 2 APPENDIX D TSS Removal Worksheets LA/V&A/V A /VfiA/V TSS Removal Project Name: 149 Main & 14 Second St Sheet: 1 of 3 100 Cambridge Street, Suite 1310 Project Number: 151025801 Date: 11-Nov-2022 Boston, MA 02114 Location: North Andover, MA Computed by: HH Discharge Point: A& B Checked by: Drainage Area(s): A-2 & B-3 A B C D E TSS Removal Starting TSS Amount Removed, Remaining Load BMP* Rate* Load** (C' D) (D-E)', Water Quality unit 80% 1.00 0.80 0.20 0% 0.20 0.00 0.20 1 L 0% 0.20 0.00 0.20 1 L 0% 0.20 0.00 0.20 0% 0.20 0.00 0.20 I L * BMP and TSS Removal Rate Values from the MassDEP Stormwater Handbook Vol. 1. Treatment Train Removal rates for proprietary devices are from approved studies and/or manufacturer 80% data (attach study or data source, or remove this sentence if not applicable). TSS R@fYIOVaI = *" Equals remaining load from previous BMP (E) \\langan.com\data\BOS\Data5\151028501\Project Data\_Discipline\Site Civil\Stormwater\149 Main Street TSS A /VfiA /V TSS Removal Calculation Worksheet Project Name: 149 Main 8 14 Second St Sheet: 2 of 3 100 Cambridge Street, Suite 1310 Project Number: 151025801 Date: 29-Dec-2022 Boston, MA 02114 Location: North Andover, MA Computed by: HH Discharge Point: Sub. Infiltration System Checked by: Drainage Area(s): B-2 (Pre-treatment) A B C D E TSS, Re,maval Starting TSS, Amount Removed Remaining Load' BMP* Rate,* Load** ('C*D), (D-E), Trench Drain Filter 80% 1.00 0.80 0.20 0% 0.20 0.00 0.20 I L 0% 0.20 0.00 0.20 I L 0% 0.20 0.00 0.20 I L 0% 0.20 0.00 0.20 * BMP and TSS Removal Rate Values from the MassDEP Stormwater Handbook Vol. 1. Treatment Traln Removal rates for proprietary devices are from approved studies and/or manufacturer data 80% (attach study or data source, or remove this sentence if not applicable). TSS R@IIIOVaI = ** Equals remaining load from previous BMP (E) \\1angan.com\data\BOS\data5\151028501\Project Data\_Discipline\Site Civil\Stormwater\149 Main Street TSS A /VfiA/V TSS Removal Project Name: 149 Main & 14 Second St Sheet: 3 of 3 100 Cambridge Street, Suite 1310 Project Number: 151025801 Date: 11-Nov-2022 Boston, MA 02114 Location: North Andover, MA Computed by: HH Discharge Point: Sub. Infiltration System Checked by: Drainage Area(s): 13-2 (treatment) A B C D E TSS Removal Starting TSS Amount Removed, Remaining Load BMP* Rate* Load** (C' D) (D-E)', Subsurface Infiltration 80% 1.00 0.80 0.20 Structure 0% 0.20 0.00 0.20 I L 0% 0.20 0.00 0.20 1 L 0% 0.20 0.00 0.20 1 L 0% 0.20 0.00 0.20 11 JL-- 11 11 * BMP and TSS Removal Rate Values from the MassDEP Stormwater Handbook Vol. 1. Treatment Train Removal rates for proprietary devices are from approved studies and/or manufacturer 80% data (attach study or data source, or remove this sentence if not applicable). TSS R@fYIOVaI = *" Equals remaining load from previous BMP (E) \\langan.com\data\BOS\Data5\151028501\Project Data\_Discipline\Site Civil\Stormwater\149 Main Street TSS Oldcastle Infrastructure TM TECHNICAL NOTE ic A CRH COMPANY FLOGARD + PLUS 0 Independent field tests conducted in Hawaii and New Zealand on FloGard +PLUS° Catch Basin Insert Filters to determine removal efficiency of Total Suspended Solids (TSS). Results were extrapolated to a typical street deposited sediment particle size. Removal efficiencies were plotted and reflect effective TSS removal over atypical range of operating flow rates. Results are shown below as a function of unit internal surface area. FloGard+Plus® TSS Removal Typical Urban Runoff Distribution* *extrapolated from available field test data 1880 E 40 Q) 20 0 20 40 60 80 100 120 140 Flux(gpm/sq ft) ® FloGard+Plus Linear(FloGard+Plus) Street Deposited Sediment Typical Particle Size Distribution Units are sized to fit most common styles of from urban runoff TSS survey data g drainage inlet rate frames or inlet widths. Rated filtered flow capacities for each model typically >,o so 8 .o 0.0 J J J J J exceed the required "first flush" treatment flow � -0 -0 60.0 rate, and account for reduction in capacity as the cc E. 40.o unit accumulates suspended pollutants. Rated � .__ .�' p IL LL (D 20.0 0.0 bypass capacity for each model also typically 10 100 1000 10000 exceeds the inlet capacity of the catch basin. Particle Size (micron) A Woodward-Clyde(1997) Honolulu Street Sediment(2004) FloGard+PLUS®Test Results Summary FloGard +PLUS° Catch Basin Insert Filter is an efficient %Oil&Grease inlet prefilter designed to remove suspended sediment Testing Agency %TSS Removal Removal and floatable trash and hydrocarbons from stormwater UCLA 80* 70-80 y U of Auckland runoff in new or retrofit applications. It is ideal) suited Tonkin&Taylor LTD 95** pp y 78-86*** for removal of primary pollutants from paved surfaces (City of Auckland) in commercial and residential areas, or may form art UofHawaii 80*** y p (City of Honolulu) of a treatment train. The device features a unique dual- *Sand larger than-575 pm bypass design, durable components, flexible installation **Sand distribution-100-1000 Pm ***Local street sweep material(distribution consistent with NURP) options and easy maintenance access. See product specifications for standard model details. www.oldcastleinfrastructure.com 1 800-579-8819 ""'It e�r w C6#'-4'�',":-NTECH8 I namic Separation Prodtict.", Calculator ENGINEERED SOLUTIONS 149 Main Street A-2 CDS 2015-4 Project Name 149 Main Street Option# A Country UNITED—STATES State Massachusetts City North Andover First Name Hilary Last Name Holmes Company Phone# 617-824-9100 Email hholmes@langan.com Site Designation A-2 Sizing Method Net Annual Screening Required? Yes Drainage Area(ac) 0.17 Peak Flow(cfs) 1.32 Groundwater Depth(ft) 5-10 Pipe Invert Depth(ft) 0-5 Bedrock Depth(ft) >15 Multiple Inlets? No Grate Inlet Required? No Pipe Size(in) 12.00 Required Particle Size No 900 between two N/A 1800 between inlet and No Distribution? inlets? outlet? Runoff Coefficient 0.90 Rainfall Station 67-Groveland,MA TIC(Min) 6 Treatment Unit CDS System Model 2015-4 Target Removal 80% Particle Size Distribution 125 Predicted Net Annual 99.68% (PSD) Removal C6#'-4'1�',`:-NTECH8 t tydrodynamic Separation Prodiwil, Calculator ENGINEERED SOLUTIONS 149 Main Street A-2 CDS 2015-4 Rainfall % Rainfall Cumulative Rainfall Total Flowrate Treated Flowrate Operating Rate Removal Incremental Intensity'(in/hr) Volume' Rainfall Volume Volume (cfs) (cfs) N Efficiency Removal Treated 0.0800 41.04% 41.04% 41.04% 0.0122 0.0122 1.74% 100.00% 41.04% 0.1600 23.88% 64.92% 23.88% 0.0245 0.0245 3.50% 100.00% 23.88% 0.2400 11.53% 76.45% 11.53% 0.0367 0.0367 5.24% 100.00% 11.53% 0.3200 7.42% 83.87% 7.42% 0.0490 0.0490 7.00% 100-00% 7.42% 0.4000 4.45% 88.32% 4.45% 0.0612 0.0612 8.74% 99.66% 4.43% 0.4800 2.90% 91.22% 2.90% 0.0734 0.0734 10.49% 99.31% 2.88% 0.5600 1.78% 93.00% 1.78% 0.0857 0.0857 12.24% 98.96% 1.76% 0.6400 1.18% 94.18% 1.18% 0.0979 0.0979 13.99% 98.61% 1.16% 0.7200 1.60% 95.78% 1.60% 0.1102 0.1102 15.74% 98.26% 1.57% 0.8000 0.79% 96-57% 0.79% 0.1224 0.1224 17.49% 97.91% 0.77% 1.0000 0.57% 97.14% 0.57% 0.1530 0.1530 21.86% 97.04% 0.55% 1.4000 1.44% 98.58% 1.44% 0.2142 0.2142 30.60% 95.29% 1.37% 1.8000 0.91% 99.49% 0.91% 0.2754 0.2754 39.34% 93.54% 0.85% 2.2000 0.51% 100.00% 0.51% 0.3366 0.3366 48.09% 91.79% 0.47% 99.68% Removal Efficiency Adjustment2= Predicted%Annual Rainfall Treated= 100.00% Predicted Net Annual Load Removal Efficiency= 99.68% 1 -Based on 7 years of data from NCDC station#3276,Groveland,Essex County,MA 2-Reduction due to use of 60-minute data for a site that has a time of concentration less than 30-minutes. C6#'-4'�',":-NTECH8 I namic Separation Prodtict.", Calculator ENGINEERED SOLUTIONS 149 Main Street B-3 CDS 2015-4 Project Name 149 Main Street Option# A Country UNITED—STATES State Massachusetts City North Andover First Name Hilary Last Name Holmes Company Phone# 617-824-9100 Email hholmes@langan.com Site Designation B-3 Sizing Method Net Annual Screening Required? Yes Drainage Area(ac) 0.06 Peak Flow(cfs) 0.40 Groundwater Depth(ft) 5-10 Pipe Invert Depth(ft) 0-5 Bedrock Depth(ft) >15 Multiple Inlets? No Grate Inlet Required? No Pipe Size(in) 12.00 Required Particle Size No 900 between two N/A 1800 between inlet and No Distribution? inlets? outlet? Runoff Coefficient 0.90 Rainfall Station 67-Groveland,MA TIC(Min) 6 Treatment Unit CDS System Model 2015-4 Target Removal 80% Particle Size Distribution 125 Predicted Net Annual 99.97% (PSD) Removal C6#'-4'1�',`:-NTECH8 t tydrodynamic Separation Prodiwil, Calculator ENGINEERED SOLUTIONS 149 Main Street B-3 CDS 2015-4 Rainfall % Rainfall Cumulative Rainfall Total Flowrate Treated Flowrate Operating Rate Removal Incremental Intensity'(in/hr) Volume' Rainfall Volume Volume (cfs) (cfs) N Efficiency Removal Treated 0.0800 41.04% 41.04% 41.04% 0.0043 0.0043 0.61% 100.00% 41.04% 0.1600 23.88% 64.92% 23.88% 0.0086 0.0086 1.23% 100.00% 23.88% 0.2400 11.53% 76.45% 11.53% 0.0130 0.0130 1.86% 100.00% 11.53% 0.3200 7.42% 83-87% 7.42% 0.0173 0.0173 2.47% 100-00% 7.42% 0.4000 4.45% 88.32% 4.45% 0.0216 0.0216 3.09% 100.00% 4.45% 0.4800 2.90% 91.22% 2.90% 0.0259 0.0259 3.70% 100.00% 2.90% 0.5600 1.78% 93.00% 1.78% 0.0302 0.0302 4.31% 100.00% 1.78% 0.6400 1.18% 94.18% 1.18% 0.0346 0.0346 4.94% 100.00% 1.18% 0.7200 1.60% 95.78% 1.60% 0.0389 0.0389 5.56% 100.00% 1.60% 0.8000 0.79% 96-57% 0.79% 0.0432 0.0432 6.17% 100-00% 0.79% 1.0000 0.57% 97.14% 0.57% 0.0540 0.0540 7.71% 99.87% 0.57% 1.4000 1.44% 98.58% 1.44% 0.0756 0.0756 10.80% 99.25% 1.43% 1.8000 0.91% 99.49% 0.91% 0.0972 0.0972 13.89% 98.63% 0.90% 2.2000 0.51% 100.00% 0.51% 0.1188 0.1188 16.97% 98.01% 0.50% 99.97% Removal Efficiency Adjustment2= Predicted%Annual Rainfall Treated= 100.00% Predicted Net Annual Load Removal Efficiency= 99.97% 1 -Based on 7 years of data from NCDC station#3276,Groveland,Essex County,MA 2-Reduction due to use of 60-minute data for a site that has a time of concentration less than 30-minutes. NJCAT TECHNOLOGY VERIFICATION HIGH EFFICIENCY CONTINUOUS DEFLECTIVE SEPARATOR (CDSO) CONTECH CONSTRUCTION PRODUCTS Inc. January 2010 5. Performance Claim verification Given that the performance standard is based on TSS-SM, and TSS-SM removal efficiency results for this study are associated with suspended solids with a d50 greater than 100µm, the review of additional data was required to further understand removal efficiency results. In general, removal efficiency results in excess of 90% are not typical for a flow through gravity separation technology but are within the realm of expected performance associated with observed influent TSS-SM EMCs with a d50 greater than 100µm. In an effort to isolate suspended sediment removal efficiency based on specific particle size ranges, SSC samples were sieved prior to analysis. The particle size ranges that were isolated for this study include 6350µm to 1.5 µm, 2000 µm to 1.5 µm, 5 00 µm to 1.5 µm, and 5 0 µm to 1.5 µm. The isolation of suspended solids removal efficiency based on particles 500µm to 1.5 µm with d50 less than 100µm and particles between 50µm and 1.5 µm with a d50 less than 50µm resulted in an overall removal efficiency of 97% and 65% respectively. The use of these results is proposed to confirm favorable removal of solids and in order to satisfy the site qualification requirements (d50< 100um) as per New Jersey Tier II Stormwater Test Requirements Amendments to TARP Tier II Protocol (NJDEP, 2006) and the NJDEP interpretation of TARP (2003). Additionally, these results demonstrate performance greater than 60% removal (65% SSC<50µm) of suspended solids with a d50 less than 50µm. Past research has concluded that when coarse particles are not present results obtained with the SSC method differ very little from results obtained using the TSS method (Gray et al 2000, Guo 2006), so results of the SSC<50um analysis are expected to be representative of TSS results. Focusing on finer solids fractions also reduces the potential for bias towards the sampling of coarse mineral solids using accepted sampling techniques. Finer mineral particles smaller than 50µm (Silt (mineral)) are generally expected to be more or less uniformly distributed throughout the water column. In addition to SSC, removal efficiency based on mineral particles smaller than 50µm was isolated. Silt (mineral) results were calculated by subtracting the volatile suspended solids results (TVSS (<50gm)) composed of combustible materials assumed to be organic in nature from the suspended solids results (SSC (<50gm)). Removal efficiency based on Silt (Mineral) results resulted in an overall removal efficiency of 69%. Recognizing the potential of a limited number of storm events to dominate sum of loads performance efficiency calculations, storm events with TSS-SM (<2000gm) EMCs less than 500 mg/1 were segregated from the data set and evaluated. Significant reductions for suspended solids loads were observed between influent and effluent sampling locations: SSC (<2000gm) 85%, TSS-SM (<2000gm) 82%, TSS-EPA (<20OOgm) 80%, SSC (<500gm) 81%, SSC (<50gm) 58%, and Silt (mineral) 65%. The primary purpose of this project was to document High Efficiency CDS system performance with respect to suspended solids removal and quantify performance in accordance with the TARP Protocol for Stormwater Best Management Practice Demonstrations and NJDEP Tier II monitoring requirements. 39 The High Efficiency CDS unit model PMSU20-25 (CDS2025) installed online at the Manasquan Savings Bank study site sized based on the New Jersey Water Quality Design Storm to treat a maximum water quality flow rate of 1.6 cfs and a peak flow of 5.43 cfs demonstrated significant suspended solids removal including greater than 60% removal of suspended solids with a d50 less than 50gm. The CDS2025 also demonstrated the ability to remove greater than 80% of stormwater solids when the influent particle size distribution is predominantly sand sized particles (50-2000 microns). 6. Net Environmental Benefit The High Efficiency CDS unit requires no input of raw material, has no moving parts and therefore uses no water or energy other than that provided by stormwater runoff. During the I I- month monitoring period the mass of materials captured and retained by the High Efficiency CDS unit was approximately 1300 kg (2860 lbs). This material would otherwise have been released to the environment during runoff producing rain events. 7. References CONTECH Stormwater Solutions Inc.(CONTECH) (2007). Quality Assurance Project Plan for Manasquan Savings Bank High Efficiency CDS6 Model PMSU20-25 Field Evaluation Portland, Oregon. Gray, J.R., Glysson, D.G., Turcios, M. L., and Schwarz, E.G. (2000). Comparability of Suspended-Sediment Concentration and Total Suspended Solids Data. U.S. Geological Survey Investigations Report 00-4191. Available Online: http://water.usgs.gov/osw/pubs/WRIR00-4191.pdf New Jersey Department of Environmental Protection (NJDEP). (2006). New Jersey Tier 11 Stormwater Test Requirements—Amendments to TARP Tier 11 Protocol. Trenton, New Jersey. Available online: http://www.state.nj.us/dep/dsr/bscit/NJStormwater TierILpdf Technology Acceptance and Reciprocity Partnership (TARP). (2003). The Technology Acceptance Reciprocity Partnership Protocol for Stormwater Best Management Practice Demonstrations. Harrisburg, Pennsylvania. Available online: http://www.dep.state.pa.us/dep/deputate/Pollprev/techservices/tarp/pdffiles/Tier2protocoI.pdf United States Environmental Protection Agency (USEPA). (2002). Urban Stormwater BMP Performance Monitoring: A Guidance Manual for Meeting the National Stormwater BMP Database Requirements (EPA-821-B-02-001). Washington, D.C. Available Online: http://epa.gov/waterscience/stormwater/montcomplete.pdf U.S. Geological Survey (USGS). (1980). Water Resources Division by Office of Water Quality (OWQ) Technical Memorandum No. 80.17 40 APPENDIX E Stormwater Collection System Calculations LA/VSA/V Hvaratiow Storm tsewers extension for AutoaeSKU UIVII ;suw Flan s TD-104 OCS-202 Second 5 Main Street 12" 6 Infiltration & Street 18" Drain Line Detention 4 3 Drain Line 7� System TD-202 4MH-101 MH-201 (WQU) (WQU) Roof Leader TD-103 2 1 Infiltration & Detention Outfall-Infiltration & System Detention System Project File: (2023-01-04)149 Main Street.stm Number of lines:8 Date: 1/4/2023 Storm Sewers v2022.00 Storm Sewer Inventory Report Page 1 Line Alignment Flow Data Physical Data Line ID No. Dnstr Line Defl Junc Known Drng Runoff Inlet Invert Line Invert Line Line N J-Loss Inlet/ Line Length angle Type Q Area Coeff Time El Dn Slope El Up Size Shape Value Coeff Rim El No. (ft) (deg) (cfs) (ac) (C) (min) (ft) M (ft) (in) (n) (K) (ft) 1 End 18.222 0.000 Grate 0.00 0.06 0.83 6.0 97.25 0.99 97.43 12 Cir 0.012 1.00 99.10 PIPE-4 2 End 9.221 -108.79 MH 0.00 0.17 0.90 6.0 97.25 0.98 97.34 12 Cir 0.012 1.00 100.71 PIPE-3 3 End 32.104 0.000 MH 0.00 0.00 0.00 0.0 91.68 1.71 92.23 12 Cir 0.012 1.00 96.31 PIPE-2 4 3 17-412 88.986 Grate 0.00 0.20 0.83 6.0 92.33 0.98 92.50 12 Cir 0.012 1.00 95.50 PIPE-1 5 End 22.144 0.000 MH 0.00 0.00 0.00 0.0 96.49 1.54 96.83 12 Cir 0.012 1.00 100.10 PIPE-8 6 5 5.035 18.890 Genr 2.33 0.00 0.00 0.0 97.20 0.99 97.25 12 Cir 0.012 1.00 100.27 PIPE-5 7 5 9.562 109.269 MH 0.00 0.00 0.00 0.0 96.93 0.00 96.93 12 Cir 0.012 0.91 100.05 PIPE-7 8 7 5.576 63.382 Grate 0.00 0.06 0.83 6.0 97.03 1.08 97.09 12 Cir 0.012 1.00 99.91 PIPE-6 Project File: (2023-01-04) 149 Main Street.stm Number of lines:8 Date: 1/4/2023 Storm Sewers v2022.00 Structure Report Page 1 Struct Structure ID Junction Rim Structure Line Out Line In No. Type Elev Shape Length Width Size Shape Invert Size Shape Invert (ft) (ft) (in) (ft) (in) (ft) 1 TD-1 03 Grate 99.10 Cir 0.83 0.83 12 Cir 97.43 2 RL-1 05 Manhole 100.71 Cir 0.83 0.83 12 Cir 97.34 3 MH-101 (WQU) Manhole 96.31 Cir 4.00 4.00 12 Cir 92.23 12 Cir 92.33 4 TD-1 04 Grate 95.50 Cir 0.83 0.83 12 Cir 92.50 5 OCS-202 Manhole 100.10 Cir 4.00 4.00 12 Cir 96.83 12 Cir 97.20 12 Cir 96.93 6 CON-B Generic 100.27 Cir 0.83 0.83 12 Cir 97.25 7 MH-201 (WQU) Manhole 100.05 Cir 4.00 4.00 12 Cir 96.93 12 Cir 97.03 8 TD-201 Grate 99.91 Cir 0.83 0.83 12 Cir 97.09 Project File: (2023-01-04) 149 Main Street.stm Number of Structures:8 Run Date: 1/4/2023 Storm Sewers v2022.00 Storm S ewer S u m mary Repo rt Page 1 Line Line ID Flow Line Line Line Invert Invert Line HGL HGL Minor HGL Dns Junction No. rate Size shape length EL Dn EL Up Slope Down Up loss Junct Line Type (cfs) (in) (ft) (ft) (ft) M (ft) (ft) (ft) (ft) No. 1 PIPE-4 0.40 12 Cir 18.222 97.25 97.43 0.988 97.51 97.69 0.09 97.69 End Grate 2 PIPE-3 1.22 12 Cir 9.221 97.25 97.34 0.976 97.71 97.80 n/a 97.80 End Manhole 3 PIPE-2 1.31 12 Cir 32.104 91.68 92.23 1.713 92.16 92.71 0.19 92.71 End Manhole 4 PIPE-1 1.32 12 Cir 17.412 92.33 92.50 0.976 92.74 92.98 n/a 92.98 3 Grate 5 PIPE-8 2.72 12 Cir 22.144 96.49 96.83 1.535 97.20 97.54 n/a 97.54 j End Manhole 6 PIPE-5 2.33 12 Cir 5.035 97.20 97.25 0.993 97.76 97.90 n/a 97.90 5 Generic 7 PIPE-7 0.39 12 Cir 9.562 96.93 96.93 0.000 97.54 97.54 0.01 97.55 5 Manhole 8 PIPE-6 0.40 12 Cir 5.576 97.03 97.09 1.076 97.55 97.35 0.09 97.35 7 Grate Project File: (2023-01-04)149 Main Street.stm Number of lines:8 Run Date: 1/4/2023 NOTES: Return period=25 Yrs. ;j-Line contains hyd.jump. Storm Sewers v2022.00 Storm Sewer Tabulatio n Page 1 Station Len Drng Area Rnoff Area x C Tc Rain Total Cap Vel Pipe Invert Elev HGL Elev Grnd I Rim Elev Line ID coeff (1) flow full Line To Incr Total Incr Total Inlet Syst Size Slope Dn Up Dn Up Dn Up Line (ft) (ac) (ac) (C) (min) (min) (in/hr) (cfs) (cfs) (ft1s) (in) M (ft) (ft) (ft) (ft) (ft) (ft) 1 End 18.222 0.06 0.06 0.83 0.05 0.05 6.0 6.0 7.9 0.40 3.83 2.44 12 0.99 97.25 97.43 97.51 97.69 99.91 99.10 PIPE-4 2 End 9.221 0.17 0.17 0.90 0.15 0.15 6.0 6.0 7.9 1.22 3.81 3.42 12 0.98 97.25 97.34 97.71 97.80 100.79 100.71 PIPE-3 3 End 32.104 0.00 0.20 0.00 0.00 0.17 0.0 6.2 7.9 1.31 5.05 3.50 12 1.71 91.68 92.23 92.16 92.71 95.31 96.31 PIPE-2 4 3 17.412 0.20 0.20 0.83 0.17 0.17 6.0 6.0 7.9 1.32 3.81 3.95 12 0.98 92.33 92.50 92.74 92.98 96.31 95.50 PIPE-1 5 End 22.144 0.00 0.06 0.00 0.00 0.05 0.0 6.5 7.8 2.72 4.78 4.57 12 1.54 96.49 96.83 97.20 97.54 98.42 100.10 PIPE-8 6 5 5.035 0.00 0.00 0.00 0.00 0.00 0.0 0.0 0.0 2.33 3.84 4.71 12 0.99 97.20 97.25 97.76 97.90 100.10 100.27 PIPE-5 7 5 9.562 0.00 0.06 0.00 0.00 0.05 0.0 6.2 7.9 0.39 0.00 0.79 12 0.00 96.93 96.93 97.54 97.54 100.10 100.05 PIPE-7 8 7 5.576 0.06 0.06 0.83 0.05 0.05 6.0 6.0 7.9 0.40 4.00 1.70 12 1.08 97.03 97.09 97.55 97.35 100.05 99.91 PIPE-6 Project File: (2023-01-04) 149 Main Street.stm Number of lines:8 Run Date: 1/4/2023 NOTES:Intensity=102.61 /(Inlet time+ 16-50)A 0.82; Return period=Yrs.25 c=cir e=ellip b=box Storm Sewers v2022.00 Hydraulic Grade L i ne Computations Page 1 Line Size Q Downstream Len Upstream Check JL Minor coeff loss Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel Vel EGL Sf Ave Enrgy elev elev head elev elev elev head elev Sf loss (in) (cfs) (ft) (ft) (ft) (sqft) (ft1s) (ft) (ft) M (ft) (ft) (ft) (ft) (sqft) (ft1s) (ft) (ft) M M (ft) (K) (ft) 1 12 0.40 97.25 97.51 0.26 0.16 2.44 0.09 97.60 0.000 18.222 97.43 97.69 0.26** 0.16 2.44 0.09 97.78 0.000 0.000 n/a 1.00 0.09 2 12 1.22 97.25 97.71 0.46 0.35 3.45 0.18 97.89 0.000 9.221 97.34 97.80 0.46** 0.36 3.40 0.18 97.98 0.000 0.000 n/a 1.00 n/a 3 12 1.31 91.68 92.16 0.48 0.37 3.52 0.19 92.35 0.000 32.104 92.23 92.71 0.48** 0.38 3.49 0.19 92.90 0.000 0.000 n/a 1.00 0.19 4 12 1.32 92.33 92.74 0.41 0.30 4.41 0.19 92.93 0.000 17.412 92.50 92.98 0.48** 0.38 3.49 0.19 93.17 0.000 0.000 n/a 1.00 n/a 5 12 2.72 96.49 97.20 0.71 0.59 4.56 0.33 97.53 0.000 22.144 96.83 97.54 j 0.71** 0.59 4.59 0.33 97.86 0.000 0.000 n/a 1.00 0.33 6 12 2.33 97.20 97.76 0.56* 0.45 5.13 0.29 98.05 0.000 5.035 97.25 97.90 0.65** 0.54 4.29 0.29 98.19 0.000 0.000 n/a 1.00 n/a 7 12 0.39 96.93 97.54 0.61 0.50 0.79 0.01 97.55 0.022 9.562 96.93 97.54 0.61 0.50 0.79 0.01 97.55 0.022 0.022 0.002 0.91 0.01 8 12 0.40 97.03 97.55 0.52 0.16 0.97 0.09 97.64 0.000 5.576 97.09 97.35 0.26** 0.16 2.44 0.09 97.44 0.000 0.000 n/a 1.00 0.09 Project File: (2023-01-04)149 Main Street.stm Number of lines:8 Run Date: 1/4/2023 Notes:* depth assumed;**Critical depth.;j-Line contains hyd.jump ; c=cir e=ellip b=box Storm Sewers v2022.00 APPENDIX F Long Term Pollution Prevention Operation and Maintenance Plans LA/V&A/V OPERATION AND MAINTENANCE PLAN Long Term Pollution Prevention Operation and Maintenance Plan for Main and Second LLC 149 Main Street & 14 Second Street North Andover, Massachusetts Parcels 030-8-0 and 030-7-0 Prepared By: Langan Engineering and Environmental Services, Inc. 100 Cambridge Street, Suite 1310 Boston, MA 02114 Prepared For: Main and Second, LLC c/o Crespo Group, LLC 65 Lewis Street East Boston, MA 02128 617.470.0339 March 2023 Langan Project No. 151028501 EiA 100 Cambridge Street, Suite 13 ston, MIA 02114 1 617.824�9100 F: 617.824.9101 www.1angan.com NIew Jersey*New York*Connecticut#Massachusetts*Pennsylvania a Washington, DC*Ohio* Hlin6s a Florida*Texas a Arizona*Colorado*Washington*California. Athens*Calgary*Dubai*ILorldon* Panania Operation and Maintenance Plan 149 Main Street and 14 Second Street, North Andover, MA Long Term Pollution Prevention Operation and Maintenance Plan The purpose of this Long Term Pollution Prevention Operation and Maintenance Plan ("O&M") is to provide project specific information related to the long term operation, maintenance, inspection, documentation, and performance of the structural and non-structural stormwater features. Regular inspection and maintenance of the stormwater management system is necessary to ensure proper operation of the system. The following 0&M has been prepared to ensure the proposed system functions as intended. This 0&M plan identifies maintenance procedures, schedules, and responsible parties. The Long Term Pollution Prevention Operation and Maintenance Plan has been compiled in general accordance with Federal, State, and Local requirement in addition to stormwater best management practices ("BMPs"). Responsible Parties Main and Second LLC, or any successor of, shall be the party responsible for implementing this 0&M plan. Main and Second LLC c/o Crespo Group 65 Lewis Street East Boston, MA 02128 Name and Title Kyle Young Signature,.,.,.,,,,,,,,,,„ Date 2/10/2023 Stormwater Operation and Maintenance Procedures Procedures are obtained from the Massachusetts Stormwater Handbook. These procedures are for all structural and non-structural BMPs and are intended to eliminate or reduce the long term soil erosion and degradation of stormwater features following construction completion. The inspection and successful implementation of all stormwater measures, shall be the Property Manager's responsibility. The Property Manager is responsible for training employees to perform 0&M and to provide ongoing training as needed in response to staff changes. Implement employee training program and hold session at least once a year. Operation and Maintenance Plan 149 Main Street and 14 Second Street, North Andover, MA Estimated Annual Costs The estimated annual cost for the implementation of this plan is $5,000. Stormwater Management Plan Overview Stormwater runoff is managed on site through the use of an underground closed pipe network with trench drains, trench drain filters, proprietary hydrodynamic separators, and underground infiltration/detention system. Structural Pretreatment BMPs Trench Drain and Proprietary Trench Drain Filters Activity Frequency Inspect units (all trench drains) Three times per year Clean units. Remove sediment, trash and other Three times per year trapped pollutants. (all trench drains) Inspect filter medium (proprietary trench drain Three times per year filters) Replace filter medium (proprietary trench drain Annually filters) • Refer to manufacturer's maintenance procedures attached to this document. Proprietary Hydrodynamic Separators Aetivity Frequency Inspect in,accordance with Manufacturer requuirem,e t , but no less tsar twice a See activity y installation,n taon, and no less t than once a year thereafter. ........................................................................................................................................................................................................................................................................................................................................................................................................................ year following leer ove sediment ent and other trapped ollutants at frequency or level specified y See anuu'acturer. manufacturer ioration • Refer to manufacturer's maintenance procedures attached to this document. Underground Structural BMPs Outlet Control Structures and Underground Detention Systems Activity Frequency Inspect inlets and outlet control structures Twice a year Remove sediment, trash and other trapped As required. pollutants. 0 Refer to manufacturer's maintenance procedures attached to this document. Operation and Maintenance Plan 149 Main Street and 14 Second Street, North Andover, MA Material and Equipment Storage Material and equipment storage shall be done in a safe and orderly fashion. All debris and waste shall be collected and disposed of offsite in a legal manner in accordance with local and federal guidelines. Snow Removal & Storage & Deicing Materials All accumulated snow on the property which materially interferes with parking, traffic circulation, pedestrian access, and sight distances, shall be hauled off-site by a commercial hauler as soon as reasonably practicable, and disposed of in accordance with the MassDEP's Bureau of Water Resources Snow Disposal Guidance (Rev. December 11, 2020). There will be no on site snow storage. Emergency vehicle access will be kept clear of snow. Deicing materials may be applied to areas such as sidewalks, site access drives, and parking areas before a storm event. Alternative materials to salt, such as calcium chloride and calcium magnesium acetate should be considered. Use of salt for deicing should be minimized on site. Deicing materials should be used with discretion in accordance with standard practices and over application must be avoided. Deicing materials shall be stored inside the buildings. After the winter season, all parking areas and walkways shall be cleaned of sediment and debris. Spill Control & Containment The following measures must be implemented to minimize, control, and contain spills: • Store chemicals inside, when applicable • Pick up litter • The spill shall be contained as close to the source as possible with a dike of absorbent materials from the spill cleanup equipment (such as socks, pads, pillows, or "pigs"). Additional dikes must be constructed to protect swales or other stormwater conveyances or streams. A cover or dike will shall protect any other stormwater structures such as catch basins. • Implement employee training program and hold session at least once a year • Identify spill control team. The name(s) of the responsible spill personnel will be posted on-site. • Each employee will be instructed that all spills are to be reported to the spill prevention and cleanup coordinator. The supervisor will assess the incident and initiate proper containment and response procedures immediately upon notification. Workers should avoid direct contact with spilled materials during the containment procedures. Operation and Maintenance Plan 149 Main Street and 14 Second Street, North Andover, MA • In the event of a release of oil or hazardous waste to the storm drainage system, the person shall immediately notify the Town's Fire and Public Works Departments and the Board of Health. • Notifications in person or by phone shall be confirmed by written notice addressed and mailed to the Town within three business days of the phone notice. • If the discharge of prohibited materials emanates from a commercial facility, the facility owner or operator of the facility shall retain on-site a written record of the discharge and the actions taken to prevent its recurrence. Such records shall be retained in accordance with the Massachusetts Public Records Law. Pesticides and Fertilizers • Pesticide/Herbicide Usage — No pesticides are to be used unless a single spot treatment is required for a specific control application. • Fertilizer usage should be avoided. If deemed necessary, slow release fertilizer should be used. Fertilizer may be used to begin the establishment of vegetation in bare or damaged areas, but should not be applied on a regular basis unless necessary Operation and Maintenance Plan 149 Main Street and 14 Second Street, North Andover, MA STORMWATER MANAGEMENT SYSTEM INSPECTION AND MAINTENANCE CHECKLIST 149 Main Street and 14 Second Street, North Andover Inspector: Date: Time Site Conditions: Inspection & Maintenance Item Schedule Satisfactory? Comments or Corrective Measures Taken Yes (Y) or No (N) Trench Drains Inspect Units 3x a year Y N Clean Units 3x a year Y N Proprietary Separators Inspect per Manufacture 2x a year Recommendations - See manufacturer Y N maintenance guide Remove Sediments and Pollutants Level of sediment has reached 50% of Y N sump capacity Proprietary Trench Filters Inspect per Manufacture 3x a year Recommendations - See manufacturer Y N maintenance guide Inspect for standing water, sediment, 3x a year Y N trash and debris and clogging Remove trash and debris and sediment 3x a year Y N Inspect to determine if system drains in Annually during wet Y N 72 hours season after large storms Inspect filter medium 3x a year Y N Replace filter medium Annually Y N Underground Detention or Infiltration Inspect outlet and inlet structures 2x a year Y N Remove Sediments and Pollutants Annually Y N Operation and Maintenance Plan 149 Main Street and 14 Second Street, North Andover, MA STORMWATER MANAGEMENT SYSTEM MAINTENANCE LOG FORM 149 Main Street and 14 Second Street North Andover, MA No. Description of Maintenance Activity Date Staff or Contractor Comments or Follow-up Items C%1'0";i'=NT CH8 ENGINEERED SOLUTIONS CDS0 Inspection and Maintenance Guide 1;;11111111.............. /%"M t �"/�............... -. ........... ASM INS TECHNOLOGIES Maintenance Cleaning The CDS system should be inspected at regular intervals and Cleaning of a CDS systems should be done during dry weather maintained when necessary to ensure optimum performance. conditions when no flow is entering the system. The use of a The rate at which the system collects pollutants will depend more vacuum truck is generally the most effective and convenient heavily on site activities than the size of the unit. For example, method of removing pollutants from the system. Simply remove unstable soils or heavy winter sanding will cause the grit chamber the manhole covers and insert the vacuum hose into the sump. to fill more quickly but regular sweeping of paved surfaces will The system should be completely drained down and the sump slow accumulation. fully evacuated of sediment.The area outside the screen should also be cleaned out if pollutant build-up exists in this area. Inspection In installations where the risk of petroleum spills is small, liquid Inspection is the key to effective maintenance and is easily contaminants may not accumulate as quickly as sediment. performed. Pollutant transport and deposition may vary from However, the system should be cleaned out immediately in year to year and regular inspections will help ensure that the the event of an oil or gasoline spill should be cleaned out system is cleaned out at the appropriate time. At a minimum, immediately. Motor oil and other hydrocarbons that accumulate inspections should be performed twice per year(e.g. spring on a more routine basis should be removed when an appreciable and fall) however more frequent inspections may be necessary layer has been captured. To remove these pollutants, it may in climates where winter sanding operations may lead to rapid be preferable to use absorbent pads since they are usually less accumulations, or in equipment washdown areas. Installations expensive to dispose than the oil/water emulsion that may be should also be inspected more frequently where excessive created by vacuuming the oily layer. Trash and debris can be amounts of trash are expected. netted out to separate it from the other pollutants. The screen The visual inspection should ascertain that the system should be power washed to ensure it is free of trash and debris. components are in working order and that there are no Manhole covers should be securely seated following cleaning blockages or obstructions in the inlet and separation screen. activities to prevent leakage of runoff into the system from above The inspection should also quantify the accumulation of and also to ensure that proper safety precautions have been hydrocarbons, trash, and sediment in the system. Measuring followed. Confined space entry procedures need to be followed pollutant accumulation can be done with a calibrated dipstick, if physical access is required. Disposal of all material removed tape measure or other measuring instrument. If absorbent from the CDS system should be done in accordance with local material is used for enhanced removal of hydrocarbons, the level regulations. In many jurisdictions, disposal of the sediments may of discoloration of the sorbent material should also be identified be handled in the same manner as the disposal of sediments during inspection. It is useful and often required as part of an removed from catch basins or deep sump manholes. operating permit to keep a record of each inspection. A simple form for doing so is provided. Access to the CDS unit is typically achieved through two manhole access covers. One opening allows for inspection and cleanoutn ; of the separation chamber(cylinder and screen) and isolated �I Fqh sump. The other allows for inspection and cleanout of sediment captured and retained outside the screen. For deep units, a single manhole access point would allows both sump cleanout and access outside the screen. � The CDS system should be cleaned when the level of sediment has reached 75%of capacity in the isolated sump or when an n, appreciable level of hydrocarbons and trash has accumulated. If absorbent material is used, it should be replaced when a� significant discoloration has occurred. Performance will not bewN impacted until 100%of the sump capacity is exceeded however *} mb � it is recommended that the system be cleaned prior to that for easier removal of sediment. The level of sediment is easily determined by measuring from finished grade down to the top of the sediment pile. To avoid underestimatingthe level of sediment in the chamber, the measuring device must be lowered �,, to the top of the sediment pile carefully. Particles at the top of �1 .k ln the pile typically offer less resistance to the end of the rod than consolidated particles toward the bottom of the pile. Once this � ��-� - measurement is recorded, it should be compared to the as-built �' drawing for the unit to determine weather the height of the r, drP 'my sediment pile off the bottom of the sump floor exceeds 75%of the total height of isolated sump. � Yy "�r`"wl� � " Y W ............... ........................................"I'll", ........... .............. ........................................... ............................................ Mill Ell III= 111= V 41 �14, 1 VIM,, 10 KIN IL�,P��� 77 77�� Support 0 Drawings and specifications are available at www.contechstormwater.com. 18 Site-specific design support is available from our engineers. (�)2017 Contech Engineered Solutions LLC,a QUIKRETE Company Contech Engineered Solutions LLC provides site solutions for the civil engineering industry.Contech's portfolio includes bridges,drainage,sanitary sewer, stormwater,earth stabilization and wastewater treament products.For information,visit www.ContechES.com or call 800.338.1122 NOTHING IN THIS CATALOG SHOULD BE CONSTRUED AS AN EXPRESSED WARRANTY OR AN IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE.SEE THE CONTECH STANDARD CONDITION OF SALES(VIEWABLE AT WWW.CONTECHES.COM/COS)FOR MORE INFORMATION. The product(s)described may be protected by one or more of the following US patents: 5,322,629;5,624,576;5,707,527;5,759,415;5,788,848; 5,985,157;6,027,639;6,350,374;6,406,218;6,641,720;6,511,595;6,649,048;6,991,114;6,998,038;7,186,058;7,296,692;7,297,266;7,517,450 related foreign patents or other patents pending. off 0 0 . 0 CDSInspection i Maintenance Log CDS Model: Location: Water Floatable Describe Maintenance Date depth to Layer Maintenance Comments Personnel sediment' Thickness' Performed 1. The water depth to sediment is determined by taking two measurements with a stadia rod:one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than the values listed in table 1 the system should be cleaned out. Note:to avoid underestimating the volume of sediment in the chamber, the measuring device must be carefully lowered to the top of the sediment pile. 2. For optimum performance,the system should be cleaned out when the floating hydrocarbon layer accumulates to an appreciable thickness. In the event of an oil spill,the system should be cleaned immediately. CDS Maintenance Guide-7/18(PDF) R=TANK OPERATION, INSPECTION & MAINTENANCE Operation Your ACF R-Tank System has been designed to function in conjunction with the engineered drainage system on your site,the existing municipal infrastructure, and/or the existing soils and geography of the receiving watershed. Unless your site included certain unique and rare features, the operation of your R-Tank System will be driven by naturally occurring systems and will function autonomously.However,upholding a proper schedule of Inspection&Maintenance is critical to ensuring continued functionality and optimum performance of the system. Inspection Both the R-Tank and all stormwater pre-treatment features incorporated into your site must be inspected regularly. Inspection frequency for your system must be determined based on the contributing drainage area, but should never exceed one year between inspections (six months during the first year of operation). Inspections may be required more frequently for pre-treatment systems. You should refer to the manufacturer requirements for the proper inspection schedule. With the right equipmentyour inspection and measurements can be accomplished from the surface without physically entering any confined spaces. If your inspection does require confined space entry,you MUST follow all local/regional requirements as well as OSHA standards. R-Tank Systems may incorporate Inspection Ports, Maintenance Ports, and/or adjoining manholes. Each of these features are easily accessed by removing the lid at the surface. With the cover removed, a visual inspection can be performed to identify sediment deposits within the structure. Using a flashlight,ALL access points should be examined to complete a thorough inspection. Inspection Ports Usually located centrally in the R-Tank System,these perforated columns are designed to give the user a base-line sediment depth across the system floor. Maintenance Ports Usually located near the inlet and outlet connections,you'll likely find deeper deposits of heavier sediments when compared to the Inspection Ports. Manholes Most systems will include at least two manholes-one at the inlet and another at the outlet. There may be more than one location where stormwater enters the system,which would result in additional manholes to inspect. Bear in mind that these manholes often include a sump below the invert of the pipe connecting to the R-Tank. These sumps are designed to capture sediment before it reaches the R-Tank,and they should be kept clean to ensure they function properly. However, existence of sediment in the sump does NOT necessarily mean sediment has accumulated in the R-Tank. After inspecting the bottom of the structure, use a mirror on a pole(or some other device)to check for sediment or debris in the pipe connecting to the R-Tank. ENVIRONMENTAL ® I t ® I 1 ■ , ► 1 a , , ►_ II Al ■ If sediment or debris is observed in any of these structures, you should determine the depth of the material. This is typically accomplished with a stadia rod, but you should determine the best way to obtain the measurement. All observations and measurements should be recorded on an Inspection Log kept on file. We've included a form you can use at the end of this guideline. Maintenance The R-Tank System should be back-flushed once sediment accumulation has reached 6"or 15%of the total system height. Use the chart below as a guideline to determine the point at which maintenance is required on your system. R-Tank Unit Max Sediment Dept Mini 9.5" 1.5" Single 17" 3" Double 34" 5" Triple 50" 6" Quad 67" 6" F_—Pent 84" 6" Before any maintenance is performed on your system, he sure to plug the outlet pipe to prevent contamination of the adjacent systems. To back-flush the R-Tank,water is pumped into the system through the Maintenance Ports as rapidly as possible. Water should be pumped into ALL Maintenance Ports.The turbulent action of the water moving through the R-Tank will suspend sediments which may then be pumped out. If your system includes an Outlet Structure, this will be the ideal location to pump contaminated water out of the system. However, removal of back-flush water may be accomplished through the Maintenance Ports, as well. For systems with large footprints that would require extensive volumes of water to properly flush the system, you should consider performing your maintenance within 24 hours of a rain event. Stormwater entering the system will aid in the suspension of sediments and reduce the volume of water required to properly flush the system. Once removed, sediment-laden water may be captured for disposal or pumped through a DirtbagTM (if permitted by the locality). 2831 Cardwell Road Richmond,Virginia,23234 A41 ctir 800.448.3636 ® FAX 804.743.7779 I S G 1 0 N111 acfenvironmental.com ENVIR40NMENTAL Step-By-Step Inspection&Maintenance Routine 1) Inspection a. Inspection Port i. Remove Cap ii. Use flashlight to detect sediment deposits iii. If present, measure sediment depth with stadia rod iv. Record results on Maintenance Log v. Replace Cap b. Maintenance Port/s i. Remove Cap ii.Use flashlight to detect sediment deposits iii. If present, measure sediment depth with stadia rod iv. Record results on Maintenance Log v. Replace Cap vi. Repeat for ALL Maintenance Ports c. Adjacent Manholes i. Remove Cover ii. Use flashlight to detect sediment deposits iii. If present, measure sediment depth with stadia rod, accounting for depth of sump (if present) iv. Inspect pipes connecting to R-Tank v. Record results on Maintenance Log vi. Replace Cover vi i. Repeat for ALL Manholes that connect to the R-Tank 2) Maintenance a. Plug system outlet to prevent discharge of back-flush water b. Determine best location to pump out back-flush water c. Remove Cap from Maintenance Port d. Pump water as rapidly as possible (without over-topping port) into system until at least 1" of water covers system bottom e. Replace Cap f. Repeat at ALL Maintenance Ports g. Pump out back-flush water to complete back-flushing h. Vacuum all adjacent structures and any other structures or stormwater pre-treatment systems that require attention i. Sediment-laden water may be captured for disposal or pumped through a DirtbagTM. j. Replace any remaining Caps or Covers k. Record the back-flushing event in your Maintenance Log with any relevant specifics ACtF R-Tank Log AazmlL3-S 3--- --3 Company Responsible Site Name: for Maintenance: Location: Contact: System Owner: Phone Number: For more information about our products,contact Inside Sales at 800.448.3636 or email at info@acfenv.com ie A CRH COMPANY Oldcastle Infrastructure"' O FLOGARD LOPRO TRENCH DRAIN FILTER Inspection and Maintenance Guide 10 ter' A division of � Water 10 Oldcastle Infrastructure TM INSPECTION AND MAINTENANCE GUIDE A CRH COMPANY SCOPE: Federal, State and Local Clean Water Act regulations and those of insurance carriers require that stormwater filtration systems be maintained and serviced on a recurring basis. The intent of the regulations is to ensure that the systems,on a continuing basis,efficiently remove pollutants from stormwater runoff thereby preventing pollution of the nation's water resources. These specifications apply to the FloGardO LoPro Trench Drain Filter. RECOMMENDED FREQUENCY OF SERVICE: Drainage Protection Systems(DPS)recommends that installed FloGard LoPro Trench Drain Filters be serviced on a recurring basis. Ultimately,the frequency depends on the amount of runoff, pollutant loading and interference from debris (leaves,vegetation,cans, paper,etc.); however, it is recommended that each installation be serviced a minimum of three times per year, with a change of filter medium once per year. DPS technicians are available to do an on-site evaluation, upon request. RECOMMENDED TIMING OF SERVICE: DPS guidelines for the timing of service are as follows: 1. For areas with a definite rainy season: Prior to, during and following the rainy season. 2. For areas subject to year-round rainfall: On a recurring basis (at least three times per year). 3. For areas with winter snow and summer rain: Prior to and just after the snow season and during the summer rain season. 4. For installed devices not subject to the elements (washracks, parking garages, etc.): On a recurring basis (no less than three times per year). SERVICE PROCEDURES: 1. The trench drain grate(s) shall be removed and set to one side. 2. The service shall commence with collection and removal of sediment and debris (litter, leaves, papers, cans, etc.). 3. The trench drain shall be visually inspected for defects and possible illegal dumping. If illegal dumping has occurred,the proper authorities and property owner representative shall be notified as soon as practicable. 4. Using an industrial vacuum,the collected materials shall be removed from the filter liner. (Note: DPS uses atruck-mounted vacuum for servicing FloGard LoPro Trench Drain Filters.) 5. When all of the collected materials have been removed,the filter assembly shall be removed from the drainage inlet. The outer filter liner shall be removed from the filter assembly and filter medium pouches shall be removed by unsnapping the tether from the interior ring and sent to one side. The filter liner, PVC body and fittings shall be inspected for continued serviceability. Minor damage or defects found shall be corrected on the spot and a notation made on the Maintenance Record. More extensive deficiencies that affect the efficiency of the filter(torn liner, etc.), if approved by the customer representative,will be corrected and a quote submitted to the representative along with the Maintenance Record. 6. The filter liner and filter medium pouches shall be inspected for defects and continued serviceability and replaced as necessary and the pouch tethers re-attached to the PVC body interior ring. 7. The grate(s) shall be replaced. 2 REPLACEMENT AND DISPOSAL OF EXPOSED FILTER MEDIUM AND COLLECTED DEBRIS The frequency of filter medium exchange will be in accordance with the existing DPS-Customer Maintenance Contract. DPS recommends that the medium be changed at least once per year. During the appropriate service, or if so determined by the service technician during anon-scheduled service, the filter medium pouches will be replaced. Once the exposed pouches and debris have been removed, DPS has possession and must dispose of it in accordance with local, state and federal agency requirements. DPS also has the capability of servicing all manner of storm drain filters,catch basin inserts and catch basins without inserts, underground oil/water separators, stormwater interceptors and other such devices. All DPS personnel are highly qualified technicians and are confined-space trained and certified.Call us at(888) 950- 8826for further information and assistance. 3 FLOGARD LOPRO TREN CH DRAIN FIL TER OUR MARKETS BUILDING COMMUNICATIONS ENERGY TRANSPORTATION STRUCTURES WATER w.oldcastleinfrastrucre.com OWa ter Oldcastlelnfrastructure' www.oldcastleinfrastructure.com oo-s�9-aeie Januaryc,:; :, 1 2 3 4 5 6 7 8 2 A V" O �3 Z a n` s B • t.a � PROPRIETARY HYDRODYNAMIC SEPARATOR z � r TRENCH DRAIN WITH PROPRIETARY 1 � ` -' `— TRENCH FILTER UNDERGROUND INFILTRATION SYSTEM C _;'j -. —�`' ._ TRENCH DRAIN i i J( f MIXEE7 S BUILDING TRENCH DRAIN Date Description No. OUTLET CONTROL STRUCTURE � Revisions PROPRIETARY HYDRODYNAMIC SEPARATOR .TRENCH DRAIN SECQNP, 9EET ---_ - LANGAN -- -- - _ � ,, #, _ Langan Engineering and Environmental Services,Inc. .. 100 Cambridge Street,Suite 1310 7 ................. ........... .... —' Boston,MA 02114 .............................................. �; ....................................,................................................................... ........... ............................._........... ,. T:617.824.9100 F:617.824.9101 www.langan.com Project e 149 MAIN STREET NORTH AN DOVER E NORTH ANDOVER ESSEX COUNTY MASSACHUSETTS Drawing Title BMP LOCATION PLAN Project No. Figure 151028501 20 0 10 20 Date SCALE IN FEET 02-09-2023 CJ•O Drawn By MPG F Checked By HH a Date:2/9/2023 Time:22:11 User:hholmes Style Table:Langan.stb Layout:CG101 Document Code:FG01-1 51 028 501-02 01-CG101-0101 APPENDIX G Illicit Discharge Compliance Statement LA/VEA/V ILLICIT DISCHARGE COMPLIANCE STATEMENT RESPONSIBILITY: The Owner is responsible for ultimate compliance with all provisions of the Massachusetts Stormwater Management Policy and responsible for identifying and eliminating illicit discharges (as defined by USEPA). OWNER NAME: Main and Second, LLC 65 Lewis Street ADDRESS: East Boston, MA 02128 617-470-0339 TEL. NUMBER: OWNER'S COMPLIANCE STATEMENT: To the best of my knowledge, the attached plans, computations and specifications meet the requirements of Standard 10 of the Massachusetts Stormwater Handbook regarding illicit discharges to the stormwater management system and that no detectable illicit discharges exist on the site. All documents and attachments were prepared under my direction and qualified personnel gathered and evaluated the information submitted, to the best of my knowledge. Included with this statement are site plans, drawn to scale, that identify the location of systems for conveying stormwater on the site and show that these systems do not allow the entry of any illicit discharges into the stormwater management system. The plans also show any systems for conveying wastewater and/or groundwater on the site and show that there are no connections between the stormwater and wastewater systems. For a redevelopment project (if applicable), all actions taken to identify and remove illicit discharges, including without limitation, visual screening, dye or smoke testing, and the removal of any sources of illicit discharges to the stormwater management system are documented and included with this statement. Name and Title Kyle Young Signature,,,,,,,,,,,, Date 2/10/2023 APPENDIX H Geotechnical Test Pits and Borings LA/VEA/V 1 2 3 4 5 6 7 8 E GENERAL NOTES z Q 1. BOUNDARY AND TOPOGRAPHIC INFORMATION OBTAINED FROM A PLAN TITLED "EXISTING AI CONDITIONS PLAN" PREPARED BY PETER . NOLAN & ASSOCIATES LLC ON 28 MARCH, 2022. PROPERTY LINE 2. SITE PLAN INFORMATION OBTAINED FROM A CONCEPT MODEL PREPARED BY JOE THE ARCHITECT (JTA) ON 05 MAY, 2022. o, I 3. ELEVATIONS SHOWN ARE BASED ON NORTH ANDOVER DATUM OD 4. BORINGS AND TEST PITS WERE PERFORMED � INC. t� BETWEEEN028 F BRUARY AND A030MARCH 2O22 TP—OZ UNDER THE OBSERVATION OF A LANGAN B =01 P-0 _ Fa FIELD ENGINEER. Ln G i Y� t � ` ° 5. ALL BORING AND TEST PIT LOCATIONS ARE CIO _ APPROXIMATE. o Ln 77, P -- P CW -04 Z t 7 gi { l " . •OLEEND no— it — — , CL CANCAN BORING - L Low . i !��,gp ,'.,, �° a G'x. t cp 4,,� - u. - ,) � s - LANGAN TEST PIT rkJ- �. , ,,;,,•, „',, 41`' sue, ,, `s;� T� l - G, i MW-01 MONITORING WELL =.i= o G a Asa BY OTHERS t ��cp t i PROPOSED BUILDING oRcr t CLINE �S Xw ii l INS- Ar V i QVI) SS it 1 E �. � �l Project D �n � e Project No. Drawing No. LA/VGA/V ORATION 151028501 co30 0 1J 30 Langan Engineering and Date Environmental Services,Inc. 149 MAIN STREET 05/26/20225 LOCATION Draw @ 100 Cambridge Street,Suite 1310 n By J SCALE: 1 INCH = 30 FEET Boston,MA02114 1Nw N P LA N Checked By T:617.824.9100 F:617.824.9101 www.langan.com NORTH ANDOVER C) ESSEX COUNTY MASSACHUSETTS1 I ZR 1 Sheet 1 of 1 @ Date:6/10/2022 Time:11:42 User:jwatler Style Table:Langan.stb Layout:FIG.5 Document Code:1 51 028501-0201-BL101-0102 LANEiA/V Log of Boring LB-01 Sheet 1 of 2 Project Project No. 149 Main Street 151028501 Location Elevation and Datum 149 Main Street,North Andover 96 NAVD88 Drilling Company Date Started Date Finished Geologic Earth Exploration Inc. 05/24/2022 05/24/2022 Drilling Equipment Completion Depth Rock Depth Mobile Drill B-57 37 ft N/E Size and Type of Bit les Disturbed Undisturbed Core 3-7/8in Tricone Roller Bit Number of Samp 6 N/A N/A Casing Diameter(in) Casing Depth(ft) First Completion 24 HR. 4in/3in 25 Water Level(ft.) �Z 4 1 N/A 7 N/A Casing Hammebonut Weight(Ibs) 300 Drop(in) 30 Drilling Foreman Z Sampler Jim Mientkiewicz 2-inch-diameter split spoon; Field Engineer z Sampler Hammer Weight(Ibs) Drop(in) Donut 140 30 Zachery Roller $ Sample Data QJ i it m Elev. Depth ; �. N-Value Remarks -E (ft) Sample Description Scale ° (Blows/ft) (Drilling Fluid,Depth of Casing, Q � � �'' m Fluid Loss,Drilling Resistance,etc.) a) +96.0 co z a 10 20 30 40 +95.7 Asphalt(4-inches) 0 Predrill through asphalt using Brown to orangish brown fine-medium SAND,some silt, 18 a 4-7/8 inch ticone roller bit some fine gravel,trace brick,trace asphalt(moist)[FILL] 1 S-1 at 0.5ft S-1A � N 14 +94.509 N Brown fine-medium SAND,some silt,trace fine gravel co 15 N (moist)[TILL] 73 2 s-1B 15 0 ' Drive casing to 4ft 3 Drive and wash to Oft o_ u Brown silty fine-medium SAND,trace clay,trace fine 4 13 S-2 at 4ft • gravel(wet)[TILL] 10 UJ 5 U) C0 18 z wi 22 ' 6 M N Drive and wash to 9ft,Open 00 o hole 7 0• 0 _J 8 J Z Gray silty fine-medium SAND,trace clay,trace fine gravel 9 6 S-3 at 9ft (wet)[TILL] 206 32 ~ 10 CO C? � 00541 O 43 w 46 Z 11 Drive and wash to 14ft,open J U hole 0 12 0 13 U w Gray silty fine-medium SAND,trace clay,trace fine gravel 14 � co 54 S-4 at 14ft o (wet)[TILL] Ch coLO 50/4 15 / 440 00 N Drive 4-inch casing to 15ft Drive and wash to 25 ft Boulder encountered from 15 16 to 16.5 feet Q 0 0 17 a 18 0 a 19 0 z Q ' J 20 LANEiA/V Log of Boring LB-01 Sheet 2 of 2 Project Project No. 149 Main Street 151028501 Location Elevation and Datum 149 Main Street,North Andover 96 NAVD88 $ Sam le Data wm Elev. Depth , ;^ N-Value Remarks � Sam le Descri tlon M Q- ° - Blows/ft (Drilling Fluid,Depth of Casing, (ft) � Scale � .� L_m ( ) Fluid Loss,Drilling Resistance,etc.) +76.0 z 0_ 10 20 30 40 51 20 21 22 z Z 23 a J i 24 O 0- � 25 Boulder encountered from 25 o_ to 27 feet LO 26 CP • Gray silty fine-medium SAND,trace clay,(wet)[TILL] 27 U N 58 S-5 at 27ft N Ch 50/3 28 Drive 3-inch casing to 27ft Drive and wash to 35ft o_ u 29 ; U) o_ w 30 w CD 31 n c N O • +64.0 ? ? ? ? 32 Drill rig reaction changed at o32ft indicated a change in soil 0 33 strata z J 34 z U 0 Gray varved SILT and CLAY,some fine to medium sand 35 25 S-6 at 35ft w (wet)[TILL] z 36 co N 39 79 40 U o +59.0 37 54 Bottom Of Boring Boring was terminated as 37ft and backfilled to grade with o soil cuttings.The pavement U 38 was patch using asphalt cold ui patch. °� 39 o_ O LO co N 40 O i LO 41 0 U) 0 42 'a a 43 0 Q 44 c� z Q J 45 LANEiA/V Log of Boring LB-02 Sheet 1 of 2 Project Project No. 149 Main Street 151028501 Location Elevation and Datum 149 Main Street,North Andover 95 NAVD88 Drilling Company Date Started Date Finished Geologic Earth Exploration Inc. 05/23/2022 05/24/2022 Drilling Equipment Completion Depth Rock Depth Mobile Drill B-57 30.1 ft N/E Size and Type of Bit les Disturbed Undisturbed Core 3-7/8in Tricone Roller Bit Number of Samp 9 N/A N/A Casing Diameter(in) Casing Depth(ft) First Completion 24 HR. 4i n 9 Water Level(ft.) �Z 6.5 1 N/A 7 5.8 Casing Hammebonut Weight(Ibs) 300 Drop(in) 30 Drilling Foreman Z Sampler Jim Mientkiewicz 2-inch-diameter split spoon; Field Engineer z Sampler Hammer Weight(Ibs) Drop(in) Donut 140 30 Zachery Roller $ Sample Data QJ i it m Elev. Depth ; �. N-Value Remarks -E (ft) Sample Description Scale ° (Blows/ft) (Drilling Fluid,Depth of Casing, Q �co � �'' m Fluid Loss,Drilling Resistance,etc.) a) +95.0 co z a 10 20 30 40 +94.7 Asphalt(4-inches) 0 Predrill through asphalt using Brown to black fine-coarse SAND,some silt,trace fine 8 a 4-7/8 inch ticone roller bit co gravel,trace asphalt,trace brick (moist)[FILL] 1 S-1 at 0.5ft N Ch20 co 8 12 c� 67 2 C' 16 +92.5 0 S-2 at 2.5ft N Brown to brown silty fine-medium SAND,trace coarse 19 sand,trace fine gravel(moist)[TILL] 3 N 31 U) N 23 w 4 CUO) 22 Brown to brown silty fine-medium SAND,trace coarse 15 Drive casing to 4ft sand(moist)[TI LL] 5 Drive and wash to 4.5ft w � Cn 17 S-3 at 4.5ft 22 CD 6 � 18 Brown to brown silty fine-medium SAND,trace clay,trace 121 18 S-4 at 6.5ft coarse sand,trace fine gravel(wet)[TILL] 7 � 13 22 0 � cn 9 z 8 11 J Drive and wash to 9ft `Z Gray to brown silt fine-medium SAND trace clay,trace 9 Drive casing to 9ft _ y y y, 20 Washed out casing to 9ft w coarse sand,trace fine gravel(wet)[TILL] 40 S-5 at 9ft 10 U) En o 34 w 44 50/5 z 11 Drive and wash to 14ft,Open hole U o 12 a 0 13 w Gray silty fine-medium SAND,trace clay,trace coarse 14 31 S-6 at 14ft o sand,trace fine gravel(wet)[TILL] cn � 60 c o 15 50/4 / 441 • Drive an wash to 19ft,Open a 16 hole Q 0 0 17 a 18 0 Graysilt fine-medium SAND,trace clay,trace coarse 19 80 S-7 at 19ft y y sand,trace fine gravel(wet)[TILL] �' So/2 / Drive and wash to 24ft,Open 20 LANEiA/V Log of Boring LB-02 Sheet 2 of 2 Project Project No. 149 Main Street 151028501 Location Elevation and Datum 149 Main Street,North Andover 95 NAVD88 $ Sam le Data w m Elev. Depth ;^ N-Value Remarks � Sam le Descri tlon M Q- ° — Blows/ft (Drilling Fluid,Depth of Casing, (ft) � Scale � .� L_m ( ) Fluid Loss,Drilling Resistance,etc.) +75.0 z 0_ 10 20 30 40 20 hole 21 22 z Z 23 a J i O J ' Gray silty fine-medium SAND,trace clay,trace coarse 4 0o 35 S-8 at 24ft o sand,trace fine gravel(wet)[TILL] �' 50/3 25 Drive and wash to 30ft,Open hole o_ co 26 CP N 27 N. O N U') 28 0_ u; 29 U) o_ ~ +64.5 No Recovery 30 s-9 ss 0 50/1 / S-9 at 30ft w, Bottom Of Boring Gravel lodged in spoon tip 31 Observation well installed at CD co 30ft with a curb-box set flush to existing grade LO 32 Refer to observation well U) construction log for more information J 33 z J 34 z U 0 35 w c? _z 36 J 0_ U U' 37 0 0 38 w °� 39 o_ co O N 40 O i a 41 0 U) 0 42 'a a 43 0 Q 44 c� z Q J 45 LANEiA/V Log of Boring LB-03 Sheet 1 of 2 Project Project No. 149 Main Street 151028501 Location Elevation and Datum 149 Main Street,North Andover 100 NAVD88 Drilling Company Date Started Date Finished Geologic Earth Exploration Inc. 05/23/2022 05/23/2022 Drilling Equipment Completion Depth Rock Depth Mobile Drill B-57 28 ft N/E Size and Type of Bit les Disturbed Undisturbed Core 3-7/8in Tricone Roller Bit Number of Samp 10 N/A N/A Casing Diameter(in) Casing Depth(ft) First Completion 24 HR. 4i n 14 Water Level(ft.) �Z 4.5 1 N/A 7 5 Casing Hammebonut Weight(Ibs) 300 Drop(in) 30 Drilling Foreman Z Sampler Jim Mientkiewicz 2-inch-diameter split spoon; Field Engineer z Sampler Hammer Weight(Ibs) Drop(in) Donut 140 30 Zachery Roller $ Sample Data QJ i it m Elev. Depth ; �. N-Value Remarks -E (ft) Sample Description Scale ° (Blows/ft) (Drilling Fluid,Depth of Casing, z �''a m Fluid Loss,Drilling Resistance,etc.) 10 20 30 40 � 100.0 +99.7 Asphalt(4-inches) 0 Predrill through asphalt using Black to orangish brown fine-medium SAND,some fine 10 a 4-7/8 inch ticone roller bit gravel,trace silt,trace asphalt (wet)[FILL] 1 �1a S-1 at 0.5ft CD Light brown to grayish fine SAND,some silt,trace co L 7 N medium sand(dry)[FILL] S_1B 6 +98.0 Light brown to grayish brown fine SAND,some silt,some 89 2 s_1c 16 c medium sand(dry)[TILL] 50 S-2 at 2.5ft N Light brown to grayish brown fine-medium SAND,some 3 silt,trace coarse sand(dry)[TILL] c� 576 cn 0 40 27 4 uj 22 • Light brown to grayish brown fine-medium SAND,some 10 Drive casing to 4ft U silt,trace clay,trace coarse sand(wet)[TILL] - 5 Drive and wash to 4.5ft 22 w 0 10 S-3 at 4.5ft i 12 0 6 18 co No Recovery 29 L S-4 at 6.5ft 7 23 U) o 534 0 30 J 8 z 37 Gravel lodged in spoon ti Brown to brown fine-medium SAND,some silt,trace clay 30 9 p p Z - L9 (n (wet)[TILL] 123 9 16 Drive and wash to 8ft,Open U U) c hole 16 S-5 at 8.5ft � 10 0 22 w w Brown to brown fine-medium SAND,some silt,trace clay, 8 S-6 at 10.5ft Z trace coarse sand,trace fine gravel(wet)[TILL] 11 cfl - 00 � 11 o_ co2 5 U 15 o� 12 23 Q. Drive casing to 1 Oft 0 13 Drive and wash to 14ft U w Gray silty fine-medium SAND,trace clay,trace coarse 14 13 S-7 at 14ft o sand,trace fine gravel(wet)[TILL] cn v 58 o 15 50/3 Drive and wash to 19ft,Open hole a 16 Q 0 0 17 a a. 18 0 U Q c� 19 -8 at 19fGray silt fine-medium AND trace clay,trace coarse S26 sand,trace fine gravel(wet)[TILL] (n 65 • 20 LANEiA/V Log of Boring LB-03 Sheet 2 of 2 Project Project No. 149 Main Street 151028501 Location Elevation and Datum 149 Main Street,North Andover 100 NAVD88 $ Sam le Data wm Elev. Depth �, ;^ N-Value Remarks � Sam le Descri tlon M Q- ° a)I—-- Blows/ft (Drilling Fluid,Depth of Casing, (ft) � Scale � .� a_m ( ) Fluid Loss,Drilling Resistance,etc.) +80.0 M z 0_ 10 20 30 40 20 Drive and wash to 24ft,open hole.S-9 at 20.08ft 21 22 z Z 23 a J i J Gray silty fine-medium SAND,trace clay,trace coarse 4 rn W N 15 0 sand,trace fine gravel(wet)[TILL] � co 50/4 25 / Drive and wash to 28ft o_ 26 o N N 27 N. O N c N +71.8 No Recovery 28 s-1 0 ss 0 50/0 / S-10 at 28ft. Bottom Of Boring Drill bit and split spoon refusal c� 29 at 28ft U) Observation well installed at o_ 28ft with a curb-box set flush w 30 to existing grade z Refer to observation well w� 31 construction log for more CD information Ln co N _O LO 32 U) 0 33 z J 34 z U 0 35 w c? _z 36 J 0_ U U' 37 0 0 38 w °� 39 o_ O LO co N 40 O i a 41 0 U) 0 42 'a a 43 0 Q 44 c� z Q J 45 LOG OF TEST PIT TP=01 Sheet 1 of 1 PROJECT NAME PROJECT NUMBER DATE 149 Main Street 151028501 5/25/2022 9:14:00 AM LOCATION ELEVATION 149 Main Street, North Andover 97 NAVD88 EXCAVATION CONTRACTOR DEPTH WATER LEVEL-First WATER LEVEL-Completion Geologic Earth Exploration Inc. 7.5 ft N/E �Z N/A 1 EQUIPMENT FOREMAN LANGAN PERSONNEL CAT 308E2 Mini-Excavator Jay Murphey Zachery Roller SAMPLE Symbol ELEV e�) DESCRIPTION Depth ) Q REMARKS Scale E z 0 Z +97.o Asphalt(4-inches) Asphalt consisted of a 1.5-inch wear course and +96.7 Orangish brown fine-medium SAND,some fine gravel,trace silt, co a 2.5-inch binder course. Q trace coarse sand(dry)[FILL] C� +96.0 1 � Grayish brown silty fine-medium SAND,some f-c gravel,trace sand,trace cobbles(moist)[TILL] 2 z z � N m 3 J U' O Q O 4 o_ N M • +92.0 --------------------------- 5 CD N Gray to brown silty fine-medium SAND,some fine gravel,trace LO clay,trace coarse sand,trace cobbles(wet)[TI LL] 6 m w M Q o_ w z 7 w O 00 o +89 5 Bottom of Test Pit Test pit was backfilled with excavated material Lco 8 up to the bottom of exiting pavement.The o pavement was patched using cold patch z asphalt. Q 9 U Z 2 w O 10 w _z J D_ U U) �, 11 'a a 0 w 0 12 0 00 N O 13 0 m 14 0 O U z 15 LANSAN J LOG OF TEST PIT TP=02 Sheet 1 of 1 PROJECT NAME PROJECT NUMBER DATE 149 Main Street 151028501 5/25/2022 12:08:00 PM LOCATION ELEVATION 149 Main Street, North Andover 99 NAVD88 EXCAVATION CONTRACTOR DEPTH WATER LEVEL-First WATER LEVEL-Completion Geologic Earth Exploration Inc. 4.67 ft 4.16 ft �Z N/A 1 EQUIPMENT FOREMAN LANGAN PERSONNEL CAT 308E2 Mini-Excavator Jay Murphey Zachery Roller SAMPLE Symbol ELEV e�) DESCRIPTION Depth ) Q REMARKS Scale E z 0 Z +99.o Asphalt(4-inches) Asphalt consisted of a 1.5-inch wear course and +98.7 Orangish brown fine-medium SAND,some silt,some fine gravel, m a 2.5-inch binder course. Q trace coarse sand(dry)[FILL] C� c� +98.0 --------------------------- 1 Brown to gray silty fine-medium SAND,some fine gravel,trace glass,trace wood,trace sand,trace asphalt,trace brick (moist)[FILL] m 2 z z J +96.1 3 0 . Mottled grayish brown silty fine-medium SAND,some fine gravel, otrace clay,trace coarse sand,trace cobbles,trace boulders C? (moist)[TILL] c� � 4+94.8 co—————————————————————————— — . Mottled grayish brown silty fine-medium SAND,some fine gravel, �! +94.3 trace clay,trace coarse sand,trace cobbles,trace boulders (wet)[TILL] 5 Test pit was backfilled with excavated material CD Bottom Of Test Pit up to the bottom of exiting pavement.The N pavement was patched using cold patch asphalt. o_ c� 6 w U) o_ w z 7 w O 00 LO O T '� 8 VJ O J H _Z Q 9 U Z 2 w O 10 w _z J D_ U U) �, 11 'a a 0 w 0 12 0 00 N O 13 0 m 14 0 O U z 15 LANSAN J LOG OF TEST PIT TP=03 Sheet 1 of 1 PROJECT NAME PROJECT NUMBER DATE 149 Main Street 151028501 5/25/2022 12:16:00 PM LOCATION ELEVATION 149 Main Street, North Andover 101 NAVD88 EXCAVATION CONTRACTOR DEPTH WATER LEVEL-First WATER LEVEL-Completion Geologic Earth Exploration Inc. 2 ft N/E �Z N/A 1 EQUIPMENT FOREMAN LANGAN PERSONNEL CAT 308E2 Mini-Excavator Jay Murphey Zachery Roller SAMPLE Symbol ELEV e�) DESCRIPTION Depth ) 0 REMARKS Scale E z 0 z +101.0 Asphalt(4-inches) Asphalt consisted of a 1.5-inch wear course and +100.7 Orangish brown fine-medium SAND,some f-c gravel,trace silt Q a 2.5-inch binder course. (dry)[FILL] +100.1 --------------------------- 1 Brown silty fine-medium SAND,some fine gravel,trace glass,trace co wood,trace brick,trace cinders(moist)[FILL] Q C� +99.0 2 Bottom Of Test Pit A concrete slab was encountered in the bottom z of the test pit.The slab extended beyond the limits of the test pit. 3 Test pit was backfilled with excavated material 0 up to the bottom of exiting pavement.The 0 pavement was patched using cold patch 4 asphalt. o_ 00 N M N N 5 O N N LO 0_ c� 6 w U) o_ w z 7 w O 00 LO O T '� 8 VJ O J H _z Q 9 U z 2 w O 10 w _z J D_ U U) �, 11 'a a 0 w 0 12 0 00 N O 13 0 m 14 0 O U z 15 LANSAN J LOG OF TEST PIT TP=04 Sheet 1 of 1 PROJECT NAME PROJECT NUMBER DATE 149 Main Street 151028501 5/25/2022 12:16:00 PM LOCATION ELEVATION 149 Main Street, North Andover 101 NAVD88 EXCAVATION CONTRACTOR DEPTH WATER LEVEL-First WATER LEVEL-Completion Geologic Earth Exploration Inc. 2 ft N/E �Z N/A 1 EQUIPMENT FOREMAN LANGAN PERSONNEL CAT 308E2 Mini-Excavator Jay Murphey Zachery Roller SAMPLE Symbol ELEV e�) DESCRIPTION Depth ) 0 REMARKS Scale E z 0 z +101.0 Asphalt(4-inches) Asphalt consisted of a 1.5-inch wear course and +100.7 Orangish brown fine-medium SAND,some f-c gravel,trace silt Q a 2.5-inch binder course. (dry)[FILL] +100.1 --------------------------- 1 Brown silty fine-medium SAND,some fine gravel,trace glass,trace co wood,trace brick,trace cinders(moist)[FILL] Q C� +99.0 2 Bottom Of Test Pit A concrete slab was encountered in the bottom z of the test pit.The slab extended beyond the limits of the test pit. 3 Test pit was backfilled with excavated material 0 up to the bottom of exiting pavement.The 0 pavement was patched using cold patch 4 asphalt. o_ 00 N M N N 5 O N N LO 0_ c� 6 w U) o_ w z 7 w O 00 LO O T '� 8 VJ O J H _z Q 9 U z 2 w O 10 w _z J D_ U U) �, 11 'a a 0 w 0 12 0 00 N O 13 0 m 14 0 O U z 15 LANSAN J WELL CONSTRUCTION SUMMARY Well No. LB-02 (OW) PROJECT 149 Main Street PROJECT NO. 151019602 LOCATION 149 Main Street,North Andover MA ELEVATION AND DATUM Approx. 95 NAVD88 DRILLING AGENCY Geologic Earth Exploration,Inc DATE STARTED 05/23/2022 DATE FINISHED 05/23/2022 DRILLING EQUIPMENT Mobile Drill B-57 DRILLER Jim Mientkiewicz SIZE AND TYPE OF BIT 3-7/8"Tri-Cone Roller Bit INSPECTOR Zachery Roller METHOD OF INSTALLATION Boring LB-02(OW)was advance to about 28.0 feet below ground surface with drive and wash drilling techniques.A slotted PVC screen and a solid PVC riser were placed into the borehole.Filter sand was poured in the annulus around the PVC to about 1 foot above the screen.An about 1 foot seal of bentonite was placed and the remainder of the borehole was backfilled with soil cuttings.The PVC was capped with a J-plug and curb-box was set flush with existing grade. METHOD OF WELL DEVELOPMENT N/A TYPE OF CASING PVC DIAMETER 2in. TYPE OF BACKFILL MATERIAL Soil Cuttings TYPE OF SCREEN PVC DIAMETER 2in. TYPE OF SEAL MATERIAL Bentonite Chips BOREHOLE DIAMETER 4-1/4" TYPE OF FILTER MATERIAL Filter sand TOP OF CASING ELEVATION DEPTH(ft) WELL DETAILS SUMMARY SOIL DEPTH el. 95 0 CLASSIFICATION (FT) TOP OF BACKFILL ELEVATION DEPTH(ft) Ground Surface 0.0 el. 95 0 Curb-box Backfill Fill 0.0 TOP OF SEAL ELEVATION DEPTH(ft) 2"PVC Seal el. 94 1 Riser TOP OF FILTER ELEVATION DEPTH(ft) Till 2.5 el. 93 2 TOP OF SCREEN ELEVATION DEPTH(ft) el. 92 3 BOTTOM OF BORING ELEVATION DEPTH(ft) el. 67 28 Sand SCREEN LENGTH 25ft Pack SLOT SIZE 1 in. PVC Screen GROUNDWATER ELEVATIONS DATE ELEVATION DEPTH TO WATER(ft) 5/25/2022 89.2 5.8 DATE ELEVATION DEPTH TO WATER(ft) 28.0 DATE ELEVATION DEPTH TO WATER(ft) DATE ELEVATION DEPTH TO WATER(ft) DATE ELEVATION DEPTH TO WATER(ft) DATE ELEVATION DEPTH TO WATER(ft) LANGAN MA,Inc. \\langan.com\data\BOS\data5\151028501\Project Data\_Discipline\Geotechnical\Field Records\151028501 GW Levels and Well Construction Logs WELL CONSTRUCTION SUMMARY Well No. LB-03 (OW) PROJECT 149 Main Street PROJECT NO. 151019602 LOCATION 149 Main Street,North Andover MA ELEVATION AND DATUM Approx. 100 NAVD88 DRILLING AGENCY Geologic Earth Exploration,Inc DATE STARTED 05/23/2022 DATE FINISHED 05/24/2022 DRILLING EQUIPMENT Mobile Drill B-57 DRILLER Jim Mientkiewicz SIZE AND TYPE OF BIT 3-7/8"Tri-Cone Roller Bit INSPECTOR Zachery Roller METHOD OF INSTALLATION Boring LB-03(OW)was advance to about 30.0 feet below ground surface with drive and wash drilling techniques.A slotted PVC screen and a solid PVC riser were placed into the borehole.Filter sand was poured in the annulus around the PVC to about 1 foot above the screen.An about 1 foot seal of bentonite was placed and the remainder of the borehole was backfilled with soil cuttings.The PVC was capped with a J-plug and curb-box was set flush with existing grade. METHOD OF WELL DEVELOPMENT N/A TYPE OF CASING PVC DIAMETER 2in. TYPE OF BACKFILL MATERIAL Soil Cuttings TYPE OF SCREEN PVC DIAMETER 2in. TYPE OF SEAL MATERIAL Bentonite Chips BOREHOLE DIAMETER 4-1/4" TYPE OF FILTER MATERIAL Filter sand TOP OF CASING ELEVATION DEPTH(ft) WELL DETAILS SUMMARY SOIL DEPTH el. 100 0 CLASSIFICATION (FT) TOP OF BACKFILL ELEVATION DEPTH(ft) Ground Surface 0.0 el. 100 0 Curb-box Backfill Fill 0.0 TOP OF SEAL ELEVATION DEPTH(ft) 2"PVC el. 97 3 Riser Seal Till 2.0 TOP OF FILTER ELEVATION DEPTH(ft) el. 96 4 TOP OF SCREEN ELEVATION DEPTH(ft) el. 95 5 BOTTOM OF BORING ELEVATION DEPTH(ft) el. 70 30 Sand SCREEN LENGTH 25ft Pack SLOT SIZE 1 in. PVC Screen GROUNDWATER ELEVATIONS DATE ELEVATION DEPTH TO WATER(ft) 5/25/2022 95.0 5.0 DATE ELEVATION DEPTH TO WATER(ft) 30.0 DATE ELEVATION DEPTH TO WATER(ft) DATE ELEVATION DEPTH TO WATER(ft) DATE ELEVATION DEPTH TO WATER(ft) DATE ELEVATION DEPTH TO WATER(ft) LLANGAN MA,Inc. \\langan.com\data\BOS\data5\151028501\Project Data\_Discipline\Geotechnical\Field Records\151028501 GW Levels and Well Construction Logs