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HomeMy WebLinkAbout2020-10-06 Application/Stormwater 1 I i STORMWATER MANAGEMENT/ TECHNICAL REPORT 335 WILLOW STREET NORTH ANDOVER, MASSACHUSETTS JULY 29, 2020 APPLICANT: MUFFIN 3X, LLC 351 WILLOW STREET NORTH ANDOVER, MA 01845 PREPARED BY: THE MORIN-CAMERON GROUP, INC, 66 ELM STREET DANVERS, MA 01923 NARRATIVE Table of Contents NARRATIVE 2 i. EXECUTIVE SUMMARY 2 II. EXISTING SITE DESCRIPTION 2 III. PROPOSED SITE DESCRIPTION 3 A. Building 3 B. Parking Area/Pedestrian Access 3 C. Earthwork and rand Disturbance 3 D. Stormwater Management Overview 3 E. Utilities 4 IV. STORMWATER MANAGEMENT 4 A. Existing Watershed Description 4 B. Proposed Watershed Description S C. Hydrologic Analysis 6 D. Stormwater Management Standards 7 V. CONCLUSION 10 FIGURES Figure 1: USGS Locus Map Figure 2: Ortho Map Figure 3: SCS Soils Map and Descriptions Figure 4: FEMA Flood Map Figure 5: Existing Watershed Plan Figure G: Proposed Watershed Plan Figure 7: Offsite Watershed Plan APPENDICIES APPENDIX A: MassDEP Stormwater Management Report Checklist APPENDIX B: Existing Conditions Hydrologic Analysis APPENDIX C: Proposed Conditions Hydrologic Analysis APPENDIX D: Stormwater Management Calculations APPENDIX E: Construction Phase Best Management Practices Plan APPENDIX F: Long Term Best Management Practices O&M Plan APPENDIX G: Illicit Discharge Statement APPENDIX H:Soli Suitability Assessment 335 Willow Street July 29, 2020 i NARRATIVE 1. EXECUTIVE SUMMARY Muffin 3X LLC., the applicant, proposes to redevelop the property located at 335 Willow Street (the "site") by renovating the existing building, constructing two building additions, reconfiguring building access and loading areas, reconstructing utilities and modifying the southern parking area. The site has 249.10' of frontage along Willow Street and is bounded by Route 125 to the West, Willow Street to the Fast and commercial properties to the North and South. The existing parking area on the South will be partially regraded, but will maintain the southern limit of pavement edge. The parking area on the North will remain with minor modifications including the addition of a concrete pad within the limits of existing pavement. The site has been designed to accommodate the proposed manufacturing and warehousing use and will comply with the Massachusetts Stormwater Standards and the North Andover Stormwater Management and Erosion Control Bylaw. The project will require Site Plan Approval from the North Andover Planning Board and an Order Of Conditions from the North Andover Conservation Commission. 11. EXISTING SITE DESCRIPTION The existing site consists of a single parcel located at 335 Wiltow street, which encompasses a total area of 156,129 sf(3.58 acres) (See Figure 1: USGS Map and Figure 2: 2013 Ortho Map for parcel location). The site is identified on the North Andover Assessor's map as Map 25, Lot 74. The existing site contains a single building with two independent associated parking and loading areas on the north and south containing a total of 63 parking spaces. The site is accessed from Willow Street with two curb cuts, which are to remain with the redevelopment. The building was most recently utilized as an office and warehouse by Jensen Tool + Supply. In 1991 an addition was constructed on the western portion of the original building. The existing building currently has a gutter and roof leader system which discharge roof runoff directly onto the ground. Runoff from the roof and parking areas flows overland to either the bordering vegetated wetland in the north-west, the bordering vegetated wetland in the south via a rip-rap discharge point or into Willow Street. Existing grades on site are relatively flat with a high elevation of 258 ft. (NAVD88)to a tow elevation of 246 ft. at the Northeast comer of the lot. The United States Department of Agriculture (USDA) Natural Resources Conservation Services (MRCS) has the soils on site mapped as Whitman fine sandy loam, 0 to 3 percent slopes, extremely stony (73A) and Woodbridge fine sandy loam, 0 to 8 percent slopes, very stony(311 B) (See Figure 3: SCS Soils Map). In situ soil testing conducted on the east side of the existing building by the Morin- Cameron Group in February 2020 confirmed the soils to be sandy loams with low to moderate permeability.The estimated seasonal high groundwater depth was relatively shallow and consistent with depths ranging 54"to 58". 2 335 Willow Street July 29, 2020 Bordering vegetated wetlands are located in the north-west, north and south-east of the site. The bordering vegetated wetland diverges away from the property heading In a south-east direction with the 100' buffer zone encompassing a majority of the southern parking area and existing building,Wetland resource areas and jurisdictional buffer zones on the site are shown on the Existing Conditions Ptan. The site is located within a FEMA flood hazard zone X (above the 100-year flood elevation) as shown on the FEMA Federal Insurance Rate Map (FIRM) #25009C0-236F with and effective date of July 3, 2012 (See Figure 4: FEMA Map). III. PROPOSED SITE DESCRIPTION A. Building The existing industrial building Is proposed to be renovated on the interior and expanded with the construction of two additions to accommodate the new proposed use. The total expansion of the building is approximately 8,700 sf. B. Parldng Area/Pedestrian Access The project includes the modification of the existing parking area to the south with the reconstruction of loading bays, construction of a refuse area, reconfiguration of building access, construction of concrete pads and associated landscaping. The southern parking area and pedestrian access has been designed to be in compliance with A©A requirements and will require minor grade changes to accommodate the proposed addition. The southern parking area will also require complete re-surfacing, re-striping and will maintain the existing limit of pavement line on the south. The northern parking area will remain with the addition of a concrete pad within the limits of the existing pavement. The reconfigured parking layout results in the removal of approximately 370 sf of pavement which will be loamed and seeded. C. Earthwork'and land Disturbance The site has been designed to limit earthwork and grade change to the extent practicable. The grading of the site was driven by the existing building elevation, existing site grades, existing bordering vegetated wetlands and stormwater requirements.The majority of the site development is limited to the south and north-east areas of the property. D. Stormwater Management Overview The stormwater management system was designed in full compliance with the Massachusetts Stormwater Handbook and North Andover Stormwater Management and Erosion Control Bylaw. Roof runoff will be collected from portions of the roof and will be directed to an underground stormwater system to provide groundwater recharge as well as peak rate attenuation. Further explanation of the stormwater management system and design methodology can be found later in this report. 3 335 Willow Street July 29, 2020 E. Utilities The proposed new use and site re-development will require all new utilities to be instatled. These include water (fire and domestic), underground electric, underground communications, sewer and natural gas. The locations are depicted on the Utility Plan. IV.STORMWATER MANAGEMENT The proposed project consist of a mix of re-developemnt and new development. The existing parking facility will not be expanded and will have a small reduction of pavement area as previously mentioned. However, the overall project wilt increase impervious area with the construction of the additions. In order to account for the increase in impervious area the project will consist of Best Management Practice (BMP) techniques in both mitigating and recharging stormwater runoff. The entire stormwater system was designed in accordance with the Massachusetts Stormwater Management Handbook and the North Andover Stormwater Management and Erosion Control Bylaw. A comprehensive Grading and Drainage Plan is included in the plan set. The existing watershed characteristics, flow paths and drainage patterns were matched to the extent practicable in the proposed condition to ensure that there are no adverse impacts to adjacent properties or wetland resource areas. A. Existing Watershed Description Drainage on site has been divided into three distinct sub-catchment areas, as shown on Figure 5: Existing Watershed Plan. The table below shows the total area for each subcatchment. Summary of Existing Subcatchments Existing Subcatchment Total Area (SF) % Impervious ES1 36,047 88.0 ES2 17,304 71.4 ES3 19,773 37.8 Totals 73,124 70.5 • Subcatchment ES1: ES1 is located at the Southwest end of the property. It is comprised mostly of the building and parking area. It sheet flows directly towards the bordering vegetated wetland to the South and discharges over a rip rap swale into the wetland which is Design Point 1 (DP1). • Subcatchment ES2: ES2 is located on the Southeastern property boundary and is comprised of building, parking area and some landscaped areas. Runoff sheet flows over the parking area and down the southern driveway entrance towards Willow street. The runoff then continues down Willow Street towards the closed street drainage system and is modeled as Design Point 2 (DP2). • Subcatchment ES3: ES3 is an area located along the Northeast property boundary and is comprised mostly of the building and parking area. It also includes some landscaped area to the East of the building between the building and Willow Street, The runoff then 4 335 Willow Street July 29, 2020 continues down Willow Street towards the closed street drainage system and is modeled as Design Point 3 (DP3). B. Proposed Watershed Descriptioti The proposed post development drainage analysis was performed by dividing the study area into six distinct sub-catchment areas (See Figure 6: Proposed Watershed Plan). Portions of the existing roof and additions are to be captured with a system of gutters and roof leaders and piped directly to an infiltration system. The table below shows the total area for each subcatchment. Summary of proposed Subcatchments Proposed Subcatchment Total Area (SA % Impervious PS1 36,284 90.1 PS2 9,331 76.4 PS2A 4,643 100.0 PS213 3,092 100.0 PS3 17,865 36.8 PS3A 1,909 100.0 Totals 73,124 76.6 • Subcatchment PS1: PS1 is located at the Southwest end of the property. It is comprised mostly of the building and parking area. It sheet flows directly towards the bordering vegetated wetland to the South and discharges over a rip rap swale into the wetland which is Design Point 1 (DP1), maintaining the existing conditions. • Subcatchment PS2: PS2 is located on the Southeastern property boundary and is comprised mostly of the building, parking area and some landscaped area. Runoff sheet flows over the parking area and down the southern driveway entrance towards.Willow street. The runoff then continues down Willow Street towards the closed street drainage system and is modeled as Design Point 2 (DP2). • Subcatchment PS2A: PS2A is comprised of the south-east corner of the building. This section of roof which is approximately 60'wide is collected with a gutter and roof leader system. The runoff is then piped to the infiltration system. The infiltration system is comprised of underground chambers and stone and has an outlet control structure to control the outflow. The outlet control structure discharges runoff that cannot be infiltrated and is ultimately piped to the Willow Street closed drainage system located to the north of the property, Design Point 3 (DP3). • Subcatchment PS213: PS213 is comprised of a section of roof(next to PS2A) which is approximately 40'wide is collected with a gutter and roof leader system. The runoff is then piped to a discharge point located under the building entrance ramp, before sheet flowing towards the southern Willow Street access driveway. The runoff then flows towards the Willow Street closed drainage system located to the south of the property, Design Point 2 (DP2). 5 I 335 Willow Street July 29, 2020 Subcatchment PS3: PS3 is an area located along the Northeast property boundary and is comprised mostly of the building and parking area. It also includes some landscaped area to the East of the building between the building and Willow Street and a gravel amenity area, The runoff sheet flows down the driveway entrance then continues down Willow Street towards the closed street drainage system, Design Point 3 (DP3). • Subcatchment PS3A: PS3 is comprised of a 30' section of the north east roof and is collected with a gutter and roof leader system. The runoff is then piped to the Infiltration system where it converges with flow from PS2A, Outflow from this system is ultimately piped to the Willow Street closed drainage system located to the north of the property, Design Point 3 (DP3). C. Hydrologic Analysis The purpose of-the stormwater analysis is to demonstrate that the proposed development will not adversely impact either the on-site or surrounding land. The industry standard for stormwater management design in Massachusetts is governed by the Massachusetts Stormwater Management Handbook ("Handbook") published by the Mass Department of Environmental Protection, January 2008. The Regulations require applicants to comply with the Handbook standards for development projects. The Handbook lists 10 standards covering both mitigation and renovation of stormwater runoff. A full discussion on the project compliance with the standards can be found at the end of this report, However, the following section will summarize the project's compliance with the mitigation standards 1 and 2 of the Handbook relating to reducing peak rates of runoff and creating no adverse down gradient impacts. To demonstrate that there will be no downstream impacts because of developing the site, a stormwater analysis was performed using the U,S. Soil Conservation Service (S.C.S) method of analysis contained in Technical Release#20 (TR-20) published by the U.S. Conservation Service, along with the extreme precipitation values published by the Northeast Regional Climate Center. The software application HydroCAD was utilized to analyze the pre and post- development watershed conditions. This analysis allows the engineer to verify that a given drainage system is adequate for the area under consideration, and further allows the engineer to predict where flooding or erosion are most likely to occur. The HydroCAD model was used to analyze the storm drainage system designed for the development to demonstrate that the drainage system complies with the State's Stormwater Management Standards and North Andover Stormwater Management and Erosion Control Bylaw. In order to more accurately represent the runoff generated from the variety of surface covers and hydrologic soil groups, the HydroCAD analysis was performed using a composite curve number generated from each subcatchment. The HydroCAD analysis was performed by examining three design points that were previously described. The following is a listing of the total pre-and post-development rates of stormwater runoff for the proposed development for the 2, 10, 25, and 100-year rainfall events; 6 335 Willow Street July 29, 2020 Comparison of Existing and Proposed s d Rates of Runoff Design Paint Storm Event Existing Conditions Proposed Conditions Change in Peak Years Peak CFS Peak CFS LFS DP-1 2 2.3 2.3 0 10 3.6 3.6 0 i 25 4.6 4.6 0 100 6.7 6.7 0 DP-2 2 1.0 0,7 -0.3 10 1.6 1.2 -0.4 25 2.1 1.6 -0.5 100 3.1 2.3 -0.8 DP-3 2 0.8 0.7 -0.1 10 1.6 1.5 -0.1 25 2.1 2.1 0 100 3.3 3.3 0 As shown in the table above the proposed development will maintain or reduce peak flow rates to DP 1, 2 and 3 for the 2, 10, 25 and 100-year design storms as required by the Massachusetts Stormwater Management Handbook and the North Andover Stormwater Management and Erosion Control Bylaw. D. Stormwater Management Standards The proposed site development will comply with all Stormwater Management Standards. Measures will also be implemented to provide the required total suspended solids (TSS) removal to ensure the stormwater runoff from the site is renovated prior to discharge. The following is an assessment of each Standard; 1. STANDARD: No stormwater conveyance system discharges untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. SUMMARY OF MITIGATING MEASURES:The project meets this standard as there are no new untreated discharges from the project site. No new pavement is proposed as part of this project and only roof runoff is proposed to be infiltrated. Since roof runoff is considered clean, no treatment is required prior to infiltration.The existing drainage patterns will be maintained to the extent practicable and the stormwater discharge locations will generally be maintained. The existing rip-rap discharge point will have sediment accumulation removed and will be re-topdressed with new rip rap to prevent erosion. 7 335 Willow Street July 29, 2020 CONCLUSION: The proposed development meets this standard. 2. STANDARD:The stormwater management system shall be designed such that post- development peak rates of stormwater runoff do not exceed pre-development rates for the 2- and 10-year storm events. SUMMARY OF MITIGATING MEASURES: The project will utilize an underground infiltration chamber system that includes an outlet structure to control the release of stormwater. As a result, the peak rate of stormwater runoff in the post-development condition is equal to or less than the existing conditions for the 2, 10, 25 and 100 year storm events. CONCLUSION:The proposed development meets this standard. 3. STANDARD: 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 when the stormwater management system is designed to infiltrate the required recharge volume as determined in accordance with the Massachusetts Stormwater handbook. SUMMARY OF MITIGATING MEASURES: A underground chamber infiltration chamber system was designed to provide groundwater recharge. The system will direct roof runoff prior to infiltration and will not require pre-treatment. The BMP will provide recharge to groundwater which will far exceed the required recharge volume. CONCLUSION: The proposed development meets this standard. 4. STANDARD: Stormwater management systems shall be designed to remove 80%of the average annual post-construction load of Total Suspended Solids (TSS). SUMMARY OF MITIGATING MEASURES: No new surfaces are proposed that requirement treatment. The existing pavement limits will be maintained and a majority of the work is within the limits of the existing pavement. Areas that were previously lawn are being converted to building and therefore will not require treatment. CONCLUSION: The proposed development meets this standard. 5. STANDARD: 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. SUMMARY OF MITIGATING MEASURES: Not applicable. CONCLUSION:The proposed development meets this standard as it does not apply to this project. 6. STANDARD: Stormwater discharges within the Zone lI 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 8 I 335 Willow Street July 29, 2020 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 Management handbook. SUMMARY OF MITIGATING MEASURES: Not applicable. CONCLUSION: The proposed development meets this standard as it does not apply to this project. 7. STANDARD: 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, 5 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, SUMMARY OF MITIGATING MEASURES: Not applicable. CONCLUSION:The proposed development meets this standard as it does not apply to this project, 8. STANDARD: 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). SUMMARY OF MITIGATING MEASURES: Refer to the Construction Phase Best Management Practices prepared by MCG, dated July 29, 2020. Since the project will disturb greater than one acre of land a SWPPP will be prepared and a NPDES Construction General Permit wilt be obtained prior to commencement of land disturbing activities on site. CONCLUSION:The proposed.devetopment meets this standard. 9. STANDARD:A long-term operation and maintenance plan shall be developed and I mplemented to ensure that stormwater management systems function as designed. SUMMARY OF MITIGATING MEASURES: Refer to the Long-Term Best Management Practices operation and Maintenance Plan prepared by MCG, dated July 29, 2020. CONCLUSION:The proposed development meets this standard. 10.STANDARD:There shall be no new illicit discharges created as a result of the project. SUMMARY OF MITIGATING MEASURES: To the best of our knowledge and belief there are no illicit discharges being created as a result of the proposed project. An illicit discharge statement is included herein. CONCLUSION:The proposed development meets this standard. 9 i 335 Willow Street July 29, 2020 V. CONCLUSION The proposed site re-development project located at 335 Willow Street, as proposed, is in full compliance with the MassDEP Stormwater Management Handbook and North Andover Stormwater Management and Erosion Control Bylaw and utilizes generally accepted engineering practices for site development. Peak rates of stormwater runoff leaving the site under proposed conditions are no greater than under existing conditions. Recharge to groundwater will be increased by adding a subsurface infiltration system. There are no illicit discharges to the waters of the Commonwealth. i I 10 335 Willow Street July 29, 2020 FIGURES Figure 1: USGS Locus Map j Figure 2: Ortho Map Figure 3: SCS Soils Map and Descriptions Figure 4: FEMA Flood Map Figure S: Existing Watershed Plan Figure 6: Proposed Watershed Plan Figure 7: Offsite Watershed Plan APPENDICIES APPENDIX A: MassDEP Stormwater Management Report Checklist APPENDIX B: Existing Conditions Hydrologic Analysis APPENDIX C: Proposed Conditions Hydrologic Analysis APPENDIX D:Stormwater Management Calculations APPENDIX E:Construction Phase Best Management Practices Plan APPENDIX F: Long Term Best Management Practices O&M Plan APPENDIX G: Illicit Discharge Statement APPENDIX H: Soil Suitability Assessment I 11 i i FIGURES 3 i ,+a� �V^-�Vr,'"•f Vey F�, t#_� ;L ..:.r�� _ � g �E I�,�� �Vdo�4s� � 1� 1 .d ,r' i9 � LL] 00 Q � ' �tu6 ;! iv �}� Nil X o1 ��� � <,� �� u fret���1Q �jQ:}� //! 1 R 1 l 4 ii �i •t � J� J 1 ' 4aj, 4 ti a1 IN A w die t a r♦ 1 tl� c r ►4-R"�,wr„ w t �1r J• ,._ � _-. — ti � I rr r ,•��pa g�f ���� r , p - •ll.l� k El��q�b 1 '.S `4 ' -RR �i�~ ��% � �;t _.•'P � k�4d1C i�1,�,� <._ LOCUS :, 1fr' a �• ` I ;� ° r'ry^ a 1 a C'�(/ F C ovV�� u �el l3el ld- ,A 870 ( r y f'} . f 0 500 1000 2000 THE MORIN-CAMERON GROUP, INC. USGS LOCUS MAP 66 ELM STREET, DANVERS, MA 0I923 335 WILLOW STREET P 1978.777.8586 F 1978.774.3488 IN WWW.MORINCAMEKON.COM NORTH ANDOVER, MA DATE:DULY 29, 2020 SCALE: I " = 1000' FIGURE # [ _j t x > All + t 4 eV, la . ITrylp 441-11 i7�� x 7a�"% ° h s �y.�,- rj4+ ":� '. a f " e �sr 7 s 1 c�' u r= - "h ff W;40 " d r r qq s � 1 nk "I Aw i L 1 r� .. e r a THE ,R WCAM ERON GROUP, INIC. ORTHO PHOTO .. ELM STREET, DANVERS, MA i 1923 WILLOW335 STREET . . r IN WWW.MOKINCAMERON.COM NORTH 1 . . 11 1 DATE: SCALE: # , �- ■ uj 0 swu IPA a . T x r I LOCU S r 73A—WHITMAN FINE SANDY LOAM 311B—WOODBRIDGE FINE SANDY LOAM 0 50 100 200 THE MORIN-CAMERONGROUP, INC. SCS SOILS MAP 66 ELM STREET, DANVERS, MA 01923 335 WILLOW STREET P 1978.777.8586 F 1978.774.3488 IN WVV V.MORINCAMERON,COM NORTH ANDOVER, MA DATE: DULY 29, 2020 T SCALE: i " = 100' FIGURE #3 02111Lu Ql�� � Q An x r r+rm e as T T. r -3 e= I r r � n " , d Locus , d 4 � iZ l r �^ ' r �, '4 u , �y . l i g r t Y�'•^rv' ark r, FEMA MAP No:25009CO236F 0 250 500 1000 THE 9 a FEMA FLOOD MAP 66 ELM STREET, DANVERS, MA o 1923 335 WILLOW STREET P 978.777.8586 F 978.774.3488 IN WWW.MORINCAMERON.COM NORTH ANDOVER, MA DATE; JULY 29, 2020 SCALE: I " = 500' FIGURE #4 I 1 APPENDIX A: MASSDEP STORMWATER MANAGEMENT REPORT CHECKLIST LlMassachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report A. Introduction Important:When A Stormwater Report must be submitted with the Notice of Intent permit application to document tilling out forms compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for on the computer, the Stormwater Report which should provide more substantive and detailed information but is offered use only the tab � { p ) key to move your here as a tool to help the applicant organize their Stormwater Management documentation for their cursor-do not Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, use the return the Stormwater Report must contain the engineering computations and supporting information set forth in key' Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and t� certified by*a Registered Professional Engineer(RPE) licensed in the Commonwealth. The Stormwater Report must include: • The Stormwater Checklist completed and stamped by a Registered Professional Engineer(see page 2) that certifies that the Stormwater Report contains all required submittals.' This Checklist is to be used as the cover for the completed Stormwater Report. • Applicant/Project Name Project Address • Name of firm and Registered Professional Engineer that prepared the Report • Long-Term Pollution Prevention Plan required by Standards 4-6 • Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan required by Standard 82 • Operation and Maintenance Plan required by Standard 9 In addition to all plans and supporting information, the Stormwater Report must include a brief narrative describing Stormwater management practices, including environmentally sensitive site design and LID techniques, along with a diagram depicting runoff through the proposed BMP treatment train, flans are required to show existing and proposed conditions, identify all wetiand resource areas, MRCS soil types, critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site where infiltration rate is greater than 2.4 Inches per hour. The Plans shall identify the drainage areas for both existing and proposed conditions at a scale that enables verification of supporting calculations. As noted in the Checklist, the Stormwater Management Report shall document compliance with each of the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the Massachusetts Stormwater Handbook. To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report Checklist by checking the box to indicate that the specified information has been included in the Stormwater Report. If any of the information specified in the checklist has not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report, The Stormwater Report may also Include the Illicit Discharge Compliance Statement required by Standard 10. if not included In the Stormwater Report,the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to the post-construction best management practices. a For some complex projects,it may not be possible to Include the Construction Period Erosion and Sedimentation Control Plan in the Stormwater Report. In that event,the Issuing authority has the discretion to Issue an Order of Conditions that approves the project and Includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site. 3908 DEP checkilst.doex•04/01108 Stormwater Report Checklist•Page 1 of 8 i LlMassachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report B. Stormwater Checklist and Certification The following checklist is intended to serve as a guide for applicants as to the elements that ordinarily need to be addressed in a complete Stormwater Report. The checklist is also intended to provide conservation commissions and other reviewing authorities with a summary of the components necessary for a comprehensive Stormwater Report that addresses the ten Stormwater Standards. Note: Because stormwater requirements vary from project to project, it is possible that a complete Stormwater Report may not include information on some of the subjects specified in the Checklist. If it is determined that a specific item does not apply to the project under review, please note that the item is not applicable (N.A.) and provide the reasons for that determination. A complete checklist must include the Certification set forth below signed by the Registered Professional Engineer who prepared the Stormwater Report. Registered Professional Engineer's Certification I have reviewed the Stormwater Report, including the soil evaluation, computations, Long-term Pollution Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan (if included), the Long- term Post-Construction Operation and Maintenance Plan, the Illicit Discharge Compliance Statement(if Included) and the plans showing the stormwater management system, and have determined that they have been prepared in accordance with the requirements of the Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist is accurate and that the information presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Registered Professional Engineer Block and Signature .lab, P A%, V JCHN M. del MCRIN 0 CIVIL a No,39836 ��Q RFGPSr���O A,FssroN oX Signatu�r�dDate Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? ❑ New development ❑ Redevelopment ® Mix of New Development and Redevelopment 3908 DEP checkllst.docx 04101/08 Stormwater Report Checklist-Page 2 of 8 LlMassachusetts department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) LID Measures: Stormwater Standards require LID measures to be considered. Document what environmentally sensitive design and LID Techniques were considered during the planning and design of the project: ® No disturbance to any Wetland Resource Areas ❑ Site Design Practices (e.g. clustered development, reduced frontage setbacks) ® Reduced Impervious Area (Redevelopment Only)(Reduced Pavement) ❑ Minimizing disturbance to existing trees and shrubs ❑ LID Site Design Credit Requested; ❑ Credit 1 ❑ Credit 2 ❑ Credit 3 ❑ Use of"country drainage"versus curb and gutter conveyance and pipe ❑ Bloretentlon Cells (includes Rain Gardens) ❑ Constructed Stormwater Wetlands (includes Gravel Wetlands designs) ❑ Treebox Filter ❑ Water Quality Swale ❑ Grass Channel ❑ Green Roof ® Other(describe); Subsurface Stormwater Recharge System Standard 1: No New Untreated Discharges ® No new untreated discharges ® Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth ® Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included. 3908 DEP checklist.docx-04/01/08 Stormwater Report Checklist-Page 3 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 2: Peak Rate Attenuation ❑ Standard 2 waiver requested because the project is located in land subject to coastal storm flowage and stormwater discharge is to a wetland subject to coastal flooding. ® Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour storm. ® Calculations provided to show that post-development peak discharge rates do not exceed pre- development rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post-development peak discharge rates do not exceed pre-development rates for the 100-year 24- hour storm. Standard 3: Recharge ® Soil Analysis provided. ® Required Recharge Volume calculation provided. ❑ Required Recharge volume reduced through use of the LID site Design Credits. ® Sizing the infiltration, BMPs is based on the following method: Check the method used. ®Static ❑ Simple Dynamic ❑ Dynamic Field' ❑ Runoff from all impervious areas at the site discharging to the infiltration BMP. ❑ Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume. ® Recharge BMPs have been sized to infiltrate the Required Recharge Volume. ❑ Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason: ❑ Site is comprised solely of C and D soils and/or bedrock at the land surface ❑ M.G.L. c. 21 E sites pursuant to 310 CMR 40,0000 ❑ Solid Waste Landfill pursuant to 310 CMR 19.000 ❑ Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable. ® Calculations showing that the infiltration BMPs will drain in 72 hours are provided. ❑ Property includes a M.G.L. c. 21 E site or a solid waste landfill and a mounding analysis is included. 80%7SS removal Is required prior to discharge to Infiltration BMP if Dynamic Meld method Is used. 3908 DEP checklist.docx 0401100 Stormwater Report Checklist•Page 4 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 3: Recharge (continued) ❑ The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10- year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided, ® Documentation Is provided showing that Infiltration BMPs do not adversely impact nearby wetland resource areas. Standard 4: Water Quality The Long-Term Pollution Prevention Plan typically includes the following: • Good housekeeping practices; • Provisions for storing materials and waste products inside or under cover; • Vehicle washing controls; • Requirements for routine inspections and maintenance of stormwater BMPs; • Spill prevention and response plans; • Provisions for maintenance of lawns, gardens, and other landscaped areas; • Requirements for storage and use of fertilizers, herbicides, and pesticides; • Pet waste management provisions; • Provisions for operation and management of septic systems; • Provisions for solid waste management; • Snow disposal and plowing plans relative to Wetland Resource Areas; • Winter Road Salt and/or Sand Use and Storage restrictions; • Street sweeping schedules; • Provisions for prevention of illicit discharges to the stormwater management system; • Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to or near critical areas or from LUHPPL; • Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan; • List of Emergency contacts for implementing Long-Term Pollution Prevention Plan. ® A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent. ❑ Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for calculating the water quality volume are included, and discharge: ❑ is within the Zone It or Interim Wellhead Protection Area ❑ is near or to other critical areas ❑ is within soils with a rapid infiltration rate(greater than 2.4 inches per hour) ❑ involves runoff from land uses with higher potential pollutant loads. ❑ The Required Water Quality Volume is reduced through use of the LID site Design Credits, ❑ Calculations documenting that the treatment train meets the 80%TSS removal requirement and, if applicable, the 44%TSS removal pretreatment requirement, are provided. 3908 DEP checktist,docx•04/01/08 Stormwater Report Checklist•Page 6 of 8 LIMassachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for stormwater Report Checklist (continued) Standard 4: Water Quality (continued) ❑ The BMP is sized (and calculations provided) based on: ❑ The'/" or V Water Qualify Volume or ❑ The equivalent flow rate associated with the Water Quality Volume and documentation is provided showing that the BMP treats the required water quality volume. ❑ The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third parry studies verifying performance of the proprietary BMPs. ❑ A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing that the BMPs selected are consistent with the TMDL is provided. Standard 6: Land Uses With Higher Potential Pollutant Loads (LUHPPLs) ❑ The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution Prevention Plan (SWPPP) has been included with the Stormwater Report. ❑ The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior to the discharge of stormwater to the post-construction stormwater BMPs. ® The NPDES Multi-Sector General Permit does not cover the land use. ❑ LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow melt and runoff, and been included in the long term Pollution Prevention Plan. ❑ All exposure has been eliminated. ❑ All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list. ❑ The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bloretention area, a sand filter or equivalent. Standard 6: Critical Areas ❑ The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP has approved for stormwater discharges to or near that particular class of critical area. ❑ Critical areas and BMPs are identified in the Stormwater Report. 3908 DEP checkl€st.docx•04101/08 Stormwater Report Checklist•Page 6 of 8 i Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable ❑ The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a: ❑ Limited Project ❑ Small Residential Projects: 5-9 single family houses or 5-9 units in a multi-family development provided there is no discharge that may potentially affect a critical area. ❑ Small Residential Projects: 2-4 single family houses or 2-4 units in a multi-family development with a discharge to a critical area ❑ Marina and/or boatyard provided the hull painting, service and maintenance areas are protected from exposure to rain, snow, snow melt and runoff ❑ Bike Path and/or Foot Path ❑ Redevelopment Project ❑ Redevelopment portion of mix of new and redevelopment. ❑ Certain standards are not fully met(Standard No. 1, 8, 9, and 10 must always be fully met) and an explanation of why these standards are not met is contained in the Stormwater Report. ❑ The project involves redevelopment and a description of all measures that have been taken to improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system(a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions. Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information: • Narrative; • Construction Period Operation and Maintenance Plan; • Names of Persons or Entity Responsible for Plan Compliance; Construction Period Pollution Prevention Measures; Erosion and Sedimentation Control Plan Drawings; Detail drawings and specifications for erosion control BMPs, including sizing calculations; • Vegetation Planning; • Site Development Plan; Construction Sequencing Plan; Sequencing of Erosion and Sedimentation Controls; Operation and Maintenance of Erosion and Sedimentation Controls; • Inspection Schedule; • Maintenance Schedule; • Inspection and Maintenance Log Form. ® A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing the information set forth above has been included in the Stormwater Report. 3908 DPP checklist.docx-04/01/08 Stormwater Report Checklist-Page 7 of 8 Massachusetts Department of Environmental Protection ELlBureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued) ❑ The project is highly complex and information is included in the Stormwater Report that explains why It Is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins. ❑ The project is not covered by a NPDES Construction General Permit. ❑ The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report. ® The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. The SWPPP will be submitted BEFORE land disturbance begins. Standard 9: Operation and Maintenance Plan ® The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information: ® Name of the stormwater management system owners; ® Party responsible for operation and maintenance; ® Schedule for implementation of routine and non-routine maintenance tasks; ® Plan showing the location of all stormwater BMPs maintenance access areas; ® Description and delineation of public safety features; ® Estimated operation and maintenance budget; and ® Operation and Maintenance Log Form. ❑ The responsible party is not the owner of the parcel where the BMP is located and the Stormwater Report Includes the following submissions: ❑ A copy of the legal instrument(deed, homeowner's association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs; ❑ A plan and easement deed that allows site access for the legal entity to operate and maintain BMP functions. Standard 10: Prohibition of Illicit Discharges ® The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges; ® An Illicit Discharge Compliance Statement is attached; ❑ NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post-construction BMPs. 390E DEP checkllst,docx•04/01/08 Stormwater Report Checklist•Page 8 of 8 1 I I 1 7 APPENDIX B: EXISTING CONDITIONS HYDROLOGIC ANALYSIS i h k ES1 ES2 . ES3 SOUT -WEST SOUT -EAST NORT EAST PARKING AREA PARKING AREA PARKIN G AREA DPI DP2 DP3 BORDERING WILLOW STREET WILLOW STREET VEGETATED (SOUTH) (NORTH) WETLAND Siacat Reach pnjnj( Routing Diagram for 3908 Pre Development Watershed Analysis Prepared by The Morin-Cameron Group, Inc., Printed 7/29/2020 HydroCADO 10.10-3a s/n 00401 O 2020 HydroCAO Software Solutions LLC I i 3908 Pre Development Watershed Analysis Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD® 10.10-3a s/n 00401 O 2020 H droCAD Software Solutions LLC ----Page 3 Soil Listing (all nodes) Area Soil Subcatahment (sq-ft) Group Numbers- 0 HSG A 0 HSG B 35,723 HSG C ES1, E52, ES3 37,401 HSG D ES1, ES2 0 Other i I 3908 Pre Development Watershed Analysis NRCC 24-hr D 2-Year Rainfall=3.95" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD® 10.10-3a s1n 00401 O 2020 H droCAD Software Solutions LLC Pa e 5 Summary for Subcatchment ES1: SOUTH-WEST PARKING AREA Runoff - 2,3 cfs @ 12,13 hrs, Volume= 8,110 cf, Depth= 2.70" Runoff by SCS TR-20 method, UH=SCS, Weighted-ON, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 2-Year Rainfall=3.15" Areas CN Description 8,213 98 Roofs, HSG D 3,844 98 Roofs, HSG C 19,150 98 Paved parking, HSG D * 86 98 Concrete, HSG C * 428 98 Concrete, HSG D 649 74 >75% Grass cover, Good, HSG C 3,677 80 >75% Grass cover, Good, HSG D 36,047 96 Weighted Average 4,326 12.00% Pervious Area 31,721 88.00% Impervious Area Tc Length Slope Velocity Capacity Description min (feet) ft/ft ft/sec cfs 6.0 Direct Entry, Direct Entry (Tc= 6 min Min.) Summary for Subcatchment ES2: SOUTHEAST PARKING AREA i Runoff - 1.0 cfs @ 12.13 hrs, Volume= 3,189 cf, Depth= 2.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 2-Year Rainfall=3.15" Area (sf) ON Description 3,152 98 Roofs, HSG C 3,414 98 Paved parking, HSG C 4,935 98 Paved parking, HSG D * 761 98 Concrete, HSG C * 97 98 Concrete, HSG D 4,044 74 >75% Grass cover, Good, HSG C 901 80 >75% Grass cover, Good, HSG D 17,304 91 Weighted Average 4,945 28.68% Pervious Area 12,359 71.42% Impervious Area Tc Length Slope Velocity Capacity Description (min) feet ftlft ftlsec cfs 6.0 Direct Entry, Direct Entry (Tc= 6 min Min.) 3908 Pre Development Watershed Analysis NRCC 24-hr D 10-Year Rainfall=4.83" Prepared by The Morin-Cameron Group, Inc. Printed 7/2912020 H droCAD® 10.10-3a s/n 00401 02020 H droCAD Software Solutions LLC Page 7 Time span=0.00-36.00 hrs, dt=0.01 hrs, 3601 points x 3 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment ES1: SOUTH-WEST Runoff Area=36,047 sf 88.00% Impervious Runoff Depth=4.36" Tc=6.0 min CN=96 Runoff=3.6 cfs 13,108 of Subcatchment ES2: SOUTH-EAST Runoff Area=17,304 sf 71.42% Impervious Runoff Depth=3.82" Tc=6.0 min CN=91 Runoff=1.6 cfs 5,504 cf Subcatchment ES3: NORTH-EAST Runoff Area=19,773 sf 37.82% Impervious Runoff Depth=3.12" Tc=6.O m€n CN=84 Runoff=1,6cfs 5,133 of Reach DP1: BORDERING VEGETATED WETLAND Inflow=3.6 cfs 13,108 of Outflow=3.6 cfs 13,108 of Reach D172: WILLOW STREET(SOUTH) Inflow=1.6 cfs 5,504 cf Outflow=1.6 cfs 5,504 of Reach DP3: WILLOW STREET(NORTH) Inflow=1.6 cfs 5,133 of Outflow=1.6 cfs 5,133 of 3908 Pre Development Watershed Analysis NRCC 24-hr D 10-Year Rainfall=4.83" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD® 10.10-3a s/n 00401 ©2020 H droCAD Software Solutions LLC Page 9 Summary for Subcatchment ES3: NORTH-EAST PARKING AREA Runoff -- 1.6 cfs @ 12.13 hrs, Volume= 5,133 cf, Depth= 3.12" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 10-Year Rainfall=4.83" Areas CN Description 3,330 98 Roofs, HSG C 3,237 98 Paved parking, HSG C 911 98 Concrete, HSG C 11,363 74 >75% Grass cover, Good, HSG C 932 96 Gravel surface, HSG C 19,773 84 Weighted Average 12,295 62.18% Pervious Area 7,478 37.82% Impervious Area Te Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 6.0 Direct Entry, Direct Entry (Tc= 6 min Min.) Summary for Reach DPI: BORDERING VEGETATED WETLAND Inflow Area = 36,047 sf, 88.00% Impervious, Inflow Depth = 4.36" for 10-Year event Inflow = 3.6 cfs @ 12.13 hrs, Volume= 13,108 cf Outflow -- 3.6 cfs @ 12.13 hrs, Volume= 13,108 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs/3 Summary for Reach DP2: WILLOW STREET (SOUTH) Inflow Area = 17,304 sf, 71.42% Impervious, Inflow Depth = 3.82" for 10-Year event Inflow - 1.6 ofs @ 12.13 hrs, Volume= 5,504 cf Outflow - 1.6 cfs @ 12.13 hrs, Volume= 5,604 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Star-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs 13 Summary for Reach DP3: WILLOW STREET (NORTH) Inflow Area = 19,773 sf, 37.82% Impervious, Inflow Depth = 3.12" for 10-Year event Inflow -- 1.6 cfs @ 12.13 hrs, Volume= 5,133 cf Outflow = 1.6 cfs @ 12.13 hrs, Volume= 5,133 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs 13 i 3908 Pre Development Watershed Analysis NRCC 24-hr D 25-Year Rainfall=6.Y6" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD® 10.10-3a s/n 00401 ©2020 H droCAD Software Solutions LLC Page 11 Summary for Subcatchment ES1: SOUTH-WEST PARKING AREA Runoff - 4.6 cfs @ 12.13 hrs, Volume 17,082 cf, Depth= 6.69" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 25-Year Rainfall=6.16" Area (so CN Description 8,213 98 Roofs, HSG D 3,844 98 Roofs, HSG C 19,150 98 Paved parking, HSG D * 86 98 Concrete, HSG C * 428 98 Concrete, HSG D 649 74 >75% Grass cover, Good, HSG C 3,677 80 >75% Grass cover, Good, HSG D 36,047 96 Weighted Average 4,326 12.00% Pervious Area 31,721 88.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (fVft) ("ec) (cfs) 6.0 Direct Entry, Direct Entry (Tc=6 min Min.) Summary for Subcatchment ES2: SOUTHEAST PARKING AREA Runoff - 2.1 cfs @ 12.13 hrs, Volume= 7,374 cf, Depth= 6.11" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt=0.01 hrs NRCC 24-hr D 25-Year Rainfali=6.16" Area (so CN^ Description 3,152 98 Roofs, HSG C 3,414 98 Paved parking, HSG C 4,935 98 Paved parking, HSG D * 761 98 Concrete, HSG C * 97 98 Concrete, HSG D 4,044 74 >75% Grass cover, Good, HSG C 901 80 >75% Grass cover, Good, HSG D 17,304 91 Weighted Average 4,945 28.58% Pervious Area 12,359 71.42% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (fUsec) (cfs) - 6.0 Direct Entry, Direct Entry (Tc 6 min Min.) I 1 3908 Pre Development Watershed Analysis NRCC 24-hr D 100-Year Rainfall=8.94" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD® 10.10-3a s/n 00401 02020 H droCAD Software Solutions LLC Pacie 13 Time span=0.00-36.00 hrs, dt=0.01 hrs, 3601 points x 3 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Star-Ind method Subcatchment ES1: SOUTH-WEST Runoff Area=36,047 sf 88.00% impervious Runoff Depth=8.46" Tc=6.0 min CN=96 Runoff=6.7 cfs 25,409 cf Subcatchment ES2: SOUTH-EAST Runoff Area=17,304 sf 71.42% Impervious Runoff Depth=7.85" Tc=6.0 min CN=91 Runoff=3,1 cfs 11,325 cf Subcatchment ES3: NORTH-EAST Runoff Area=19,773 sf 37.82% Impervious Runoff Depth=7.00" Tc=6.0 min CN=84 Runoff=3.3 cfs 11,536 of Reach DP1: BORDERING VEGETATED WETLAND Inflow=6.7 cfs 26,409 of Outflow=6.7 cfs 25,409 cf Reach DP2: WILLOW STREET(SOUTH) Inflow=3.1 cfs 11,325 cf Outflow=3.1 cfs 11,326 of Reach DP3: WILLOW STREET(NORTH) Inflow=3.3 cfs 11,536 cf Outflow=3.3 cfs 11,536 of 3908 Pre Development Watershed Analysis NRCC 24-hr D 100-Year Rainfall=&94" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD® 10.10-3a s/n 00401 02020 H droCAD Software Solutions LLC Page 15 Summary for Subcatchment E83: NORTH-EAST PARKING AREA Runoff -- 3.3 cfs @ 12.13 hrs, Volume= 11,536 cf, Depth= 7.00" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 firs NRCC 24-hr D 100-Year Rainfall=8.94" Areas CN Description 3,330 98 Roofs, HSG C 3,237 98 Paved parking, HSG C * 911 98 Concrete, HSG C * 11,363 74 >75% Grass cover, Good, HSG C 932 96 Gravel surface, HSG C 19,773 84 Weighted Average 12,295 62.18% Pervious Area 7,478 37.82% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/ft ftlsec cfs 6.0 Direct Entry, Direct Entry(Tc 6 min Min.) Summary for Reach DPI: BORDERING VEGETATED WETLAND Inflow Area - 36,047 sf, 88.00% Impervious, Inflow Depth = 8.46" for 100-Year event Inflow - 6.7 cfs @ 12.13 hrs, Volume= 25,409 cf Outflow -- 6.7 cfs @ 12.13 hrs, Volume= 25,409 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs 13 Summary for Reach DP2: WILLOW STREET (SOUTH) Inflow Area = 17,304 sf, 71.42% Impervious, Inflow Depth = 7.85" for 100-Year event I nflow - 3.1 cfs @ 12.13 hrs, Volume= 11,325 cf Outflow - 3,1 cfs. @ 12.13 hrs, Volume= 11,325 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span 0.00-36.00 hrs, dt= 0.01 hrs 13 Summary for Reach DP3: WILLOW STREET (NORTH) Inflow Area = 19,773 sf, 37.82% Impervious, inflow Depth = 7.00" for 100-Year event Inflow = 3.3 cfs @ 12.13 hrs, Volume= 11,536 cf Outflow - 3.3 cfs @ 12.13 hrs, Volume= 11,536 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs/3 i } APPENDIX C. PROPOSED CONDITIONS HYDROLOGIC ANALYSIS I i PS1 PS2 PS2A PS3 SOUT -WEST SOUTH-EAST SOUTH-EAST ROOF NORT I-EAST PARKING AREA PARKING AREA PARKI G AREA DP1 DP2 P1 �` DP3 BORDERING WILLO TREET UNDE OUND WILLOW STREET VEGETATED (SO TH) CHA BERS (NORTH) WETLAND PS2B )3A SOUTH-EAST ROOF SOUTHEAST ROOF Subcat Reach o1� jpk Routing Diagram for 3908 Post Development Watershed Analysis Prepared by The Marro-Cameron Group, Inc„ Printed 7/29/2020 HydroCAD010.10-3a sln 00401 ©2020 HydroCAD Software HUluliOnS LLC I '' i 3908 Post Development Watershed Analysis NRCC 24-hr D 10-Year Rainfall=4.83" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD® 10.10-3a s/n 00401 ©2020 H droCAD Software Solutions LLC Page 10 i Summary for Subcatchment PSI: SOUTH-WEST PARKING AREA Runoff - 3.6 cfs @ 12.13 hrs, Volume= 13,194 of, Depth= 4.36" i Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 10-Year Rainfall=4.83" Areas CN Description 10,881 98 Roofs, HSG D 3,277 98 Roofs, HSG C 15,757 98 Paved parking, HSG D 2,787 98 Concrete, HSG D 3,582 80 >75% Grass cover, Good, HSG D 36,284 96 Weighted Average 3,582 9.87% Pervious Area 32,702 90.13% Impervious Area To Length Slope Velocity Capacity Description min feet ftlft) (fYsec) (cfs 6.0 Direct Entry, Direct Entry (To= 6 min Min.) Summary for Subcatchment PS2: SOUTHEAST PARKING AREA Runoff - 0.9 cfs @ 12.13 hrs, Volume= 3,134 of, Depth= 4.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0,01 hrs NRCC 24-hr D 10-Year Rainfall=4.83" Area (sD CN Description 3,184 98 Paved parking, HSG C 3,466 98 Paved parking, HSG D 442 98 Concrete, HSG C 33 98 Concrete, HSG D 1,468 74 >75% Grass cover, Good, HSG C 738 80 >75% Grass cover, Good, HSG D 9,331 93 Weighted Average 2,206 23.64% Pervious Area 7,125 76.36% Impervious Area To Length Slope Velocity Capacity Description (min) feet ftlft fUsec cfs 6.0 Direct Entry, Direct Entry (Tc= 6 min Min.) Summary for Subcatchment PS2A: SOUTH-EAST ROOF Runoff -- 0.5 cfs @ 12.13 hrs, Volume= 1,777 of, Depth= 4.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 10-Year Rainfall=4.83" I 3908 Post Development Watershed Analysis NRCC 24-hr D 2-Year Rainfall=3.95" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD®10.10-3a s/n 00401 ®2020 H droCAD Software Solutions LLC Pa e 8 Peak Elev= 249.72' @ 12.41 hrs Surf.Area= 686 sf Storage= 546 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 239.7 min ( 1,000.5- 760.8) Volume Invert Avail.Storage Storage Description " #1A 24 8.30' 530 cf 11.17'W x 52.601 x 3.54'H Field A 2,076 cf Overall - 753 cf Embedded = 1,324 cf x 40.0% Voids #2A 248.80' 753 cf Cultee R-330XLHD x 14 Inside#1 Effective Size= 47.8"W x 30.0"H => 7.45 sf x 7.001= 52.2 cf Overall Size= 52.0"W x 30.5"H x 8.501 with 1.50' Overiap Row Length Adjustment= +1.50' x 7.45 sf x_2rows 1,282 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 248.30' 1.020 in/hr Exflltratlon over Surface area #2 Primary 248.80' 12.0" Round Culvert L=4.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 248.80' /248.80' S= 0.0000 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #3 Device 2 249,50' 3.0"Vert, Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 2 251.30' 3.0"Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 251.80' 4.0' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2,92 3.08 3.30 3.32 Discarded OutFlow Max=0.0 cfs @ 9.76 hrs HW=248.34' (Free Discharge) 'L1=Exfiltration (Exfiltration Controls 0.0 cfs) Primary OutFlow Max=0.1 cfs @ 12.41 hrs HW=249.72' TW=0.00' (Dynamic Tailwater) 2=Culvert (Passes 0.1 cfs of 1.6 cfs potential flow) 1:Orifice/Grate (Orifice Controls 0.1 cfs @ 1.60 fps) 0rifice/Grate ( Controls 0.0 cfs) =Broad-Crested Rectangular Weir (Controls 0.0 cfs) 3908 Post Development Watershed Analysis NRCC 24-hr D 2-Year Rainfall=3.95" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCADO 10.10-3a s/n 00401 ©2020 H droCAD Software Solutions LLC Page 6 _ Area (sD _ CN Description 4,643 98 Roofs, HSG C 4,643 100.00% Impervious Area Tc Length Slope Velocity Capacity Description min feet ft/f#) (ft/sec) (cfs 6.0 Direct Entry, Direct Entry (Te= 6 min Min.) Summary for Subcatchment PS213: SOUTH-EAST ROOF Runoff - 0.2 cfs @ 12.13 hrs, Volume= 752 cf, Depth= 2.92" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 2-Year Rainfall=3.15" Area (sf) CN Description 2,935 98 Roofs, HSG C 157 98 Roofs, HSG D 3,092 98 Weighted Average 3,092 100,00% Impervious Area Tc Length Slope Velocity Capacity Description (min) feet) (ftift) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry (Tc= 6 min Min.) Summary for Subcatchment PS3: NORTH-EAST PARKING AREA Runoff - 0.7 cfs @ 12.13 hrs, Volume= 2,335 cf, Depth= 1,57" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0,01 hrs NRCC 24-hr D 2-Year Rainfall=3.15" Area (sD CN Description 2,907 98 Roofs, HSG C 3,236 98 Paved parking, HSG C 429 98 Concrete, HSG C 10,843 74 >75% Grass cover, Good, HSG C 450 89 Gravel, HSG C 17,865 83 Weighted Average 11,293 63.21% Pervious Area 6,572 36.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) feet (ft/ff) (ft/sec) (cfs)_ 6.0 Direct Entry, Direct Entry (Tc= 6 min Min.) i i 3908 Post Development Watershed Analysis NRCC 24-hr D 2-Year Rainfall=3.15" Prepared by The Morn-Cameron Group, Inc. Printed 7/29/2020 H droCAD® 10.10-3a sln 00401 GO 2020 H droCAD Software Solutions LLC Page 4 Time span=0.00-36,00 hrs, dt=0.01 hrs, 3601 points x 3 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Subcatchment PS1: SOUTH-WEST Runoff Area=36,284 sf 90.13% Impervious Runoff Depth=2,70" Tc=6.0 min CN=96 Runoff=2.3 cfs 8,163 cf Subcatchment PS2: SOUTH-EAST Runoff Area=9,331 sf 76,36% Impervious Runoff Depth=2.40" Tc=6.0 min CN=93 Runoff=0.5 cfs 1,864 cf Subcatchment PS2A: SOUTH-EAST ROOF Runoff Area=4,643 sf 100,00% Impervious Runoff Depth=2.92" Tc=6,0 min CN=98 Runoff=0.3 cfs 1,129 cf Subcatchment PS213: SOUTH-EAST ROOT" Runoff Area=3,092 sf 100.00% Impervious Runoff Depth=2.92" Tc=6.0 min CN=98 Runoff=0.2 cfs 752 of Subcatchment PS3: NORTH-EAST Runoff Area=17,865 sf 36.79% Impervious Runoff Depth=1,57" Tc=6.0 min CN=83 Runoff=0.7 cfs 2,335 cf Subcatchment PS3A: SOUTH-EAST ROOF Runoff Area=1,909 sf 100.00% Impervious Runoff Depth=2.92" Tc=6.0 min CN=98 Runoff=0,1 cfs 464 of Reach DPI: BORDERING VEGETATED WETLAND Inflow=2.3 cfs 8,163 of Outflow=2.3 cfs 8,163 of Reach DP2: WILLOW STREET(SOUTH) Inflow=0.7 cfs 2,616 of Outflow=0.7 cfs 2,616 of Reach DP3: WILLOW STREET(NORTH) Inflow=07 cfs 2,651 of Outflow=0.7 cfs 2,651 of Pond P1: UNDERGROUND CHAMBERS Peak Elev=249.72' Storage=546 of Inflow=0.4 cfs 1,593 of Discarded=0.0 cfs 1,277 of Primary=0.1 cfs 316 of Outflow=0.1 cfs 1,593 of i i 3908 Post Development Watershed Analysis NRCC 24-hr D 10-Year Ralnfail=4.83" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD®10,10-3a sin 00401 CG)2020 H droCAD Software Solutions LLC Page 11 Area (sD CN Description 4,643 98 Roofs, HSG C 4,643 100.00% Impervious Area Tc Length Slope Velocity Capacity Description min feet ftlft ftlsec cfs 6.0 Direct Entry, Direct: Entry (Te 6 min Min.) Summary for Subcatchment PS213: SOUTHEAST ROOF Runoff - 0.3 cfs @ 12.13 hrs, Volume= 1,184 cf, Depth= 4.59" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 10-Year Rainfall=4.83" Areas CN Description 2,935 98 Roofs, HSG C 167 98 Roofs, HSG D E 3,092 98 Weighted Average 3,092 100.00% impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (Rift) (fYsec) (cfs) -- 6.0 Direct Entry, Direct Entry (Te 6 min Min.) Summary for Subcatchment PS3: NORTH-EAST PARKING AREA Runoff 1.4 cfs @ 12.13 hrs, Volume= 4,497 cf, Depth= 3.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 10-Year Rainfall=4.83" Areas CN Description 2,907 98 Roofs, HSG C 3,236 98 Paved parking, HSG C * 429 98 Concrete, HSG C 10,843 74 >75% Grass cover, Good, HSG C * 460 89 Gravel, HSG C 17,865 83 Weighted Average 11,293 63.21% Pervious Area 6,572 36.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ftlft) (ft/sec) (cfs) 6,0 Direct Entry, Direct Entry (Tc= 6 min Min.) 3908 Post development Watershed Analysis NRCC 24-hr O 10-Year Rainfall=4.83" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCADO 10,10-3a sin 00401 ©2020 H droCAD Software Solutions LLC Page 13 Peak Elev= 250.35' @ 12.29 hrs Surf.Area= 586 sf Storage= 824 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time 197.7 min (948.8- 751.2 Volume Invert Avall.Stora a Storage Descrl tion #1A 248.30' 530 cf 11.17'W x 52.50'L x 3.64'H Field A 2,076 cf Overall - 753 cf Embedded = 1,324 cf x 40.0% Voids #2A 248.80' 753 cf Cultec R-330XLHD x 14 Inside#1 Effective Size=47.8"W x 30.0"H => 7.45 sf x 7.001 =52.2 cf Overall Size= 52.0"W x 30.5"H x 8.501 with 1.50' Overlap Row Length Adjustment= +1.50' x 7.46 sf x 2 rows 1,282 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 248.30' 1.020 inlhr Exfiltration over Surface area - #2 Primary 248.80' 12.0" Round Culvert L=4.0' CPP, projecting, no headwall, Kew 0.900 Inlet 1 Outlet Invert= 248.80' 1248.80' S= 0.00007' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #3 Device 2 249.50' 3.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 2 251.30' 3.0"Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads 45 Primary 251.80' 4.0' tong x 0.6' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0,40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 Discarded OutFlow Max=0.0 cfs @ 7.37 hrs HW=248.34' (Free Discharge) L1=Exfiltration (Exfiltration Controls 0,0 cfs) Primary OutFlow Max=0.2 cfs @ 12.29 hrs HW=250,35' TW=0.00' (Dynamic Tailwater) 2=Culvert (Passes 0.2 cfs of 3.1 cfs potential flow) t:Orifice/Grate (Orifice Controls 0.2 cfs @ 4.10 fps) Orifice/Grate (Controls 0.0 cfs) =B road-Crested Rectangular Weir ( Controls 0.0 cfs) i 3908 Post Development Watershed Analysis NRCC 24-hr D 25-Year Rainfall=6.16" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCAD® 10.10-3a sln 00401 ©2020 H droCAD Software Solutions LLC Page 15 Summary for Subcatchment PS1: SOUTHWEST PARKING AREA Runoff - 4.6 cfs @ 12.13 hrs, Volume= 17,195 cf, Depth= 5.69" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 25-Year Rainfall=6.16" Areas CN Description 10,881 98 Roofs, HSG D 3,277 98 Roofs, HSG C 15,757 98 Paved parking, HSG D * 2,787 98 Concrete, HSG D 3,582 80 >75% Grass cover, Good, HSG D 36,284 96 Weighted Average 3,582 9.87% Pervious Area 32,702 90.13% Impervious Area Tc Length Slope Velocity Capacity Description min feet ftlft) (ftlsec) (cfs 6.0 Direct Entry, Direct Entry (Tc =6 min Min.) Summary for Subcatchment PS2: SOUTH-EAST PARKING AREA Runoff = 1.2 cfs @ 12.13 hrs, Volume= 4,153 cf, Depth= 5.34" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 25-Year Rainfall=6.16" Area (sD CN Description 3,184 98 Paved parking, HSG C 3,466 98 Paved parking, HSG D * 442 98 Concrete, HSG C * 33 98 Concrete, HSG D 1,468 74 >75% Grass cover, Good, HSG C 738 80 >75% Grass cover, Good, HSG D 9,331 93 Weighted Average 2,206 23.64% Pervious Area 7,125 76.36% Impervious Area Tc Length Slope Velocity Capacity Description min #eet ftlft ftlsec cfs 6.0 Direct Entry, Direct Entry (Tc=6 min Min.) Summary for Subcatchment PS2A: SOUTH-EAST ROOF Runoff - 0.6 cfs @ 12.13 hrs, Volume= 2,291 cf, Depth= 5.92" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs. NRCC 24-hr D 25-Year Rainfall=6.16" i 3908 Post Development Watershed Analysis NRCC 24-hr D 25-Year Rainfall=6.16" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H draCAD® 10.10-3a sin 00401 O 2020 Hy droCAD Software Solutions LLC Page 17 Summary for Subcatchment PS3A: SOUTH-EAST ROOF Runoff = 0,2 cfs @ 12.13 hrs, Volume= 942 cf, Depth= 5.92" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 25-Year Rainfall=6.16" Area (sD CN Description 1,909 98 Roofs, HSG C 1,909 100,00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ftlft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry (Tc= 6 min Min.) Summary for Reach DP1: BORDERING VEGETATED WETLAND Inflow Area = 36,284 sf, 90.13% Impervious, Inflow Depth = 6.69" for 25-Year event Inflow - 4.6 cfs @ 12.13 hrs, Volume= 17,196 cf Outflow - 4.6 cfs @ 12.13 hrs, Volume= 17,195 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Star-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs/3 Summary for Reach DP2: WILLOW STREET (SOUTH) Inflow Area = 12,423 sf, 82.24% Impervious, Inflow Depth = 5.49" for 25-Year event Inflow -- 1.6 cfs @ 12.13 hrs, Volume= 5,679 cf Outflow - 1.6 cfs @ 12.13 hrs, Volume= 5,679 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0,01 hrs/3 Summary for Reach DP3: WILLOW STREET (NORTH) Inflow Area = 24,417 sf, 53.75% Impervious, Inflow Depth = 3.92" for 25-Year event Inflow - 2.1 cfs @ 12.13 hrs, Volume= 7,974 cf Outflow - 2.1 cfs @ 12.13 hrs, Volume= 7,974 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs 13 Summary for Pond P1: UNDERGROUND CHAMBERS Inflow Area = 6,552 sf,100.00% Impervious, Inflow Depth = 6.92" for 25-Year event Inflow - 0.8 cfs @ 12.13 hrs, Volume= 3,233 cf Outflow - 0.3 cfs @ 12.29 hrs, Volume= 3,233 cf, Atten= 67%, Lag= 9.6 min Discarded = 0.0 cfs @ 5.22 hrs, Volume= 1,572 cf Primary - 0.3 cfs @ 12.29 hrs, Volume= 1,662 cf Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs/3 3908 Post Development Watershed Analysis NRCC 24-hr D 100-Year Rarnfafi=8.94 Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 ydroCADO 10.10-3a sin 00401 ©2020 HydroCAD Software Solutions LLC Page 19 Time span=0.00-36.00 hrs, dt=0.01 hrs, 3601 points x 3 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method Pond routing by Dyn-Stor-Ind method Subcatchment PSI: SOUTH-WEST Runoff Area=36,284 sf 90.13% Impervious Runoff Depth=8.46" Tc=6.0 min CN=96 Runoff=6.7 cfs 25,576 cf Subcatchment PS2: SOUTH-EAST Runoff Area=9,331 sf 76.36% Impervious Runoff Depth=8.10" Tc=6,0 min CN=93 Runoff=1.7 cfs 6,295 of Subcatchment PS2A:SOUTH-EAST ROOF Runoff Area=4,643 sf 100.00% Impervious Runoff Depth=8.70" Tc=6.0 min CN=98 Runoff=0.9 cfs 3,366 of Subcatchment PS28: SOUTH-EAST ROOF Runoff Area=3,092 sf 100,00% Impervious Runoff Depth=8.70" Tc=6.0 min CN=98 Runoff=0.6 cfs 2,242 of Subcatchment PS3: NORTH-EAST Runoff Area=17,865 sf 36.79% Impervious Runoff Depth=6,88" Tc=6.0 min CN=83 Runoff=3.0 cfs 10,241 of Subcatchment Mk SOUTH-EAST ROOF Runoff Area=1,909 sf 100.00% Impervious Runoff Depth=8.70" Tc=6.0 min CN=98 Runoff=0,4 cfs 1,384 of Reach DPI: BORDERING VEGETATED WETLAND Inflow=6.7 cfs 25,576 of Outflow=6.7 cfs 25,576 of Reach DP2: WIDOW STREET(SOUTH) Inflow=2.3 cfs 8,537 of Outflow=2.3 cfs 8,537 of Reach DP3: WILLOW STREET(NORTH) Inflow=3.3 cfs 13,365 of Outflow=3.3 cfs 13,365 of Pond PI: UNDERGROUND CHAMBERS Pear Elev=251.89' Storage=1,282 cf Inflow=1.2 cfs 4,750 of Discarded=0.0 cfs 1,626 of Primary=0.8 cfs 3,124 of Outflow=0.8 cfs 4,750 of I 3908 Post Development Watershed Analysis NRCC 24-hr D 100-Year Rainfaf=8.94" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 HydroCAD® 10.10-3a s/n 00401 ©2020 HydroCAD Software Solutions LLC _ Page 21 Area (so CN Description 4,643 98 Roofs, HSG C 4,643 100.00% Impervious Area To Length Slope Velocity Capacity Description min feet ft/ft ft/sec cfs 6.0 Direct Entry, Direct Entry (Tc =6 min Min.) Summary for Subcatchment PS2113: SOUTHEAST ROOF Runoff — 0.6 cfs @ 12.13 hrs, Volume= 2,242 of, Depth= 8.70" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36,00 hrs, dt= 0.01 hrs NRCC 24-hr D 100-Year Rainfall=8.94" Areas CN Description 2,935 98 Roofs, HSG C 157 98 Roofs, HSG D 3,092 98 Weighted Average 3,092 100,00% Impervious Area To Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Direct Entry (Tc -6 min Min.) Summary for Subcatchment PS3: NORTHEAST PARKING AREA Runoff — 3.0 cfs @ 12.13 hrs, Volume= 10,241 of, Depth= 6.88" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.01 hrs NRCC 24-hr D 100-Year Rainfall=8.94" Area (sf) CN Description 2,907 98 Roofs, HSG C 3,236 98 Paved parking, HSG C * 429 98 Concrete, HSG C 10,843 74 >75% Grass cover, Good, HSG C * 450 89 Gravel, HSG C 17,865 83 Weighted Average 11,293 63,21% Pervious Area 6,572 36.79% Impervious Area To Length Slope Velocity Capacity Description min feet ft/ft) (ft/sec) (cfs 6.0 Direct Entry, Direct Entry (Tc= 6 min Min.) 3908 Post Development Watershed Analysis NRCC 24-hr D 100-Year Rainfall=8.94" Prepared by The Morin-Cameron Group, Inc. Printed 7/29/2020 H droCADO 10.10-3a sin 00401 @ 2020 H droCAD Software Solutions LLC page 23 Peak Elev= 251.89' @ 12.20 hrs Surf.Area= 586 sf Storage= 1,282 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 144.0 min (885.2-741.2 ) Volume Invert Avall.Stora e Storage Description #1A 248.30' 530 cf 11.17'W x 52.50'L x 3.54'H Field A 2,076 cf Overall - 753 cf Embedded = 1,324 cf x 40.0% Voids #2A 248.80' 753 of Cultec R-330XLHD x 14 Inside#1 Effective Size= 47.8"W x 30.0"H => 7.45 sf x 7.001 =52.2 cf Overall Size= 52.0"W x 30.5"H x 8.501 with 1.50' Overlap Row Length Adjustment= *1.50' x 7.46 sf x 2 rows 1,282 of Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 248.30' 1.020 inlhr Exfiltration over Surface area #2 Primary 248.80' 12.0" Round Culvert L= 4.0' CPP, projecting, no headwall, Ke= 0.900 Inlet/Outlet Invert= 248.80'1248.80' S= 0.0000 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf #3 Device 2 249.50' 3.0"Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #4 Device 2 251.30' 3.0"Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #5 Primary 261.80' 4.0' long x 0.5' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 Coef. (English) 2.80 2.92 3.08 3.30 3.32 Discarded OutFlow Max=0.0 cfs @ 2.44 hrs HW=248.34' (Free Discharge) I'--1=Exflltratlon (Exfiltration Controls 0.0 cfs) Primary OutFlow Max=0.8 cfs @ 12.20 hrs HW=251.88' TW=0.00' (Dynamic Tailwater) 2=Culvert (Passes 0.5 cfs of 4.8 cfs potential flow) 3=Orifice/Grate (Orifice Controls 0.4 cfs @ 7.24 fps) =Orifice/Grate (Orifice Controls 0.2 cfs @ 3.26 fps) =Broad-Crested Rectangular Weir (Weir Controls 0.3 cfs @ 0.81 fps) APPENDIX D: STORMWATER MANAGEMENT CALCULATIONS i i July 29, 2020 Stormwater Management Calculations STANDARD 3: Recharge To Groundwater: Static Method • Calculate Impervious Area (From HydroCAD Model) Existing Impervious Area (HSG C Soil) = 51,558 SF Proposed Impervious Area (HSG C Soil) 56,043 SF • Determine Rainfall Depth to be Recharged (MassDEP Stormwater Management Handbook. Table 2.3.2) Hydrologic Sol] Group Recharge Rainfall Depth C 0.25" • Calculate Recharge Volume `Rv' = [0.25" x (56,043 SF— 51,558 SF)] ! 12 SF-In = 94 CF `Rv' 94 CF • Calculate Provided Recharge Schedule of Proposed Recharge System Volumes HCAD Bottom of Lowest System Outlet Total Recharge System ID System or Top of Galley Volume Provided P 1 248.30 249.50 446 Total Volume: 446 Recharge volume provided measured to lowest system outlet. Required Recharge Volume Summary Total Volume Provided Below Outlets = 446 CF Total Volume Required = 94 CF Verify Drawdown, Maximum 72MHours: Static Method Recharge Bottom Drawdown Time HCAD Rawls Rate Volume Surface Rv 1(K x A) Description System ID Inches/Hour (CF) Area (SF) (Hours) RS1 446 586 1.02 8.9 Subsurface Storage "Design Complies with Recharge Volume Standard" i APPENDIX E: CONSTRUCTION PHASE BEST MANAGEMENT PRACTICES PLAN i Construction Phase Best Management Practices BMP's Erosion and Sedimentation will be controlled at the site by utilizing Structural Practices, Stabilization Practices, and Dust Control. These practices correspond with plans entitled "Site Redevelopment Plans in North Andover, Massachusetts, 335 Willow Street" prepared by The Morin-Cameron Group, Inc. dated July 29, 2020 as revised and approved by the North Andover Planning Board, hereinafter referred to as the Site Plans. Responsible Party Contact Information: Stormwater Management System Owner: Muffin 3X, LLC 351 Willow Street North Andover, MA 01845 I P: (978) 683-1414 North Andover Department of Public Works: 384 Osgood Street North Andover, MA 01845 P: (978) 685-0950 North Andover Planning Board: Town Hall 120 Main Street North Andover, MA 01845 P: (978) 688-9535 North Andover Zoning Board of Appeals: Town Hall 120 Main Street North Andover, MA 01845 P: (978) 688-9545 North Andover Conservation Commission: Town Hall 120 Main Street North Andover, MA 01845 P: (978) 688-9530 Site Design Engineer Information: The Morin-Cameron Group, Inc. 66 Elm Street Danvers, MA 01923 Phone: (978) 777-8586 Best Management Practices Operation and Maintenance Plan MCG Project No. 3908, 335 Willow Street, North Andover, Massachusetts July 29, 2020-Page 1 of 9 I! 3) Sediment Tracts-Out: The site supervisor will inspect and ensure that sediment is not tracked into the roadway. If tracking onto the roadway is noted, it shall be removed immediately via by hand or a mechanical street sweeper. (If Required: Stabilized Construction Exit: Crushed stone anti-tracking pads will be installed at the entrance to the site. This will prevent trucks from tracking material onto the road from the construction site. If, at any point during the project, the tracking pad becomes ineffective due to accumulation of soil, the crushed stone shall be replaced. Details for construction of the stabilized entrance can be found in the details sheet that is part of the permit plan set associated with the project. The site supervisor will inspect the tracking pads weekly to ensure that they are properly limiting the tracking of soil onto the road. If tracking onto the roadway is noted, it shall be removed immediately via by hand or a mechanical street sweeper.) StabilIzation Practices: Stabilization measures shall be implemented as soon as practicable in portions of the site where construction activities have temporarily or permanently ceased, but in no case more than 14 days after the construction activity in that portion of the site has temporarily or permanently ceased, with the following exceptions, • Where the initiation of stabilization measures by the 1411 day after construction activity temporary or permanently cease is precluded by snow cover, stabilization measures shall be initiated as soon as practicable. • Where construction activity will resume on a portion of the site within 21 days from when activities ceased, (e.g. the total time period that construction activity is temporarily ceased is less than 21 days) then stabilization measures do not have to be initiated on that portion of the site by the 141h day after construction activity temporarily ceased. 1) Temporary Seeding --Temporary seeding will allow a short-term vegetative cover on disturbed site areas that may be in danger of erosion. Temporary seeding will be done at stock piles and disturbed portions of the site where construction activity will temporarily cease for at least 21 days. The temporary seeding will stabilize cleared and unvegetated areas that will not be brought into final grade for several weeks or months. Temporary Seeding Planting Procedures a) Planting should preferably be done between April 151 and June 301", and September 15t through September 311t. If planting is done in the months of July and August, irrigation may be required. If planting is done between October 111 and March 3151, mulching should be applied immediately after planting. b) Before seeding, install structural practice controls. Utilize Amoco supergro or equivalent. c) Select the appropriate seed species for temporary cover from the following table. Best Management Practices Operation and Maintenance Plan MCG Project No, 3908, 335 Willow Street, North Andover, Massachusetts July 29, 2020-Page 3 of 9 i Geotextile Installation a) Netting and matting require firm, continuous contact between the materials and the soil. If there is no contact, the material will not hold the soil and erosion will occur underneath the material. Geotextile Inspection/Maintenance a) In the field, regular inspections should be made to check for cracks, tears, or breaches in the fabric. The appropriate repairs should be made. 3) Mulching and Netting— Mulching will provide immediate protection to exposed soils during the period of short construction delays, or over winter months through the application of plant residues, or other suitable materials,to exposed soil areas, In areas, which have been seeded either for temporary or permanent cover, mulching should immediately follow seeding. On steep slopes, mulch must be supplemented with netting. The preferred mulching material is straw. Mulch (Hay or Straw) Materials and Installation a) Straw has been found to be one of the most effective organic mulch materials. The specifications for straw are described below, but other material may be appropriate. The straw should be air-dried; free of undesirable seeds & coarse materials. The application rate per 1,000 sq. is 90-100 lbs. (2-3 bales) and the application rate per acre is 2 tons (100-120 bales), The application should cover about 90% of the surface. The use of straw mulch is appropriate where mulch is maintained for more than three months. Straw mulch is subject to wind blowing unless anchored, is the most commonly used mulching material, and has the best microenvironment for germinating seeds. Mulch Maintenance i a) Inspect after rainstorms to check for movement of mulch or erosion. If washout, breakage, or erosion occurs, repair surface, reseed, remulch, and install new netting. b) Straw or grass mulches that blow or wash away should be repaired promptly. c) If plastic netting is used to anchor mulch, care should be taken during initial mowing to keep the mower height high. Otherwise, the netting can wrap up on the mower blade shafts. After a period of time, the netting degrades and becomes less of a problem. d) Continue inspections until vegetation is well established. 4) Land Grading—Grading on fill slopes, cut slopes, and stockpile areas will be done with full siltation controls in place. Best Management Practices Operation and Maintenance Plan MCG Project No, 3908, 335 Willow Street, North Andover, Massachusetts July 29, 2020-Page 5 of 9 a) Topsoil should not be placed while in a frozen or muddy condition, when the subgrade is excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed seeding. b) Do not place topsoil on slopes steeper than 2.5:1, as it will tend to erode. c) If topsoil and subsoil are not properly bonded, water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The best method is to actually work the topsoil into the layer below for a depth of at least 6 inches. 6) Permanent Seeding -- Permanent Seeding should be done immediately after the final design grades are achieved. Native species of plants should be used to establish perennial vegetative cover on disturbed areas. The revegetatton should be done early enough in the fall so that a good cover is established before cold weather comes and growth stops until the spring. A good cover is defined as vegetation covering 75 percent or more of the ground surface. Permanent Seedin Seedbed Preparation a) In infertile or coarse-textured subsoil, it is best to stockpile topsoil and re-spread it over the finished slope at a minimum 2 to 6-inch depth and roll it to provide a firm seedbed. The topsoil must have a sandy loam to silt loam texture with 15% to 20% organic content. If construction fill operations have left soil exposed with a loose, rough, or irregular surface, smooth with blade and rotL b) Loosen the soil to a depth of 3-5 inches with suitable agricultural or construction equipment. c) Areas not to receive topsoil shall be treated to firm the seedbed after incorporation of the time and fertilizer so that it is depressed no more than 1/2 - 1 inch when stepped on with a shoe. Areas to receive topsoil shall not be firmed until after topsoiling and lime and fertilizer is applied and incorporated, at which time it shall be treated to firm the seedbed as described above. Permanent Seeding Grass Selection/Appt[cation a) Select an appropriate cool or warm season grass based on site conditions and seeding date. Apply the seed uniformly by hydro-seeding, broadcasting, or by hand. Uniform seed distribution is essential. On steep slopes, hydroseeding may be the most effective seeding method. Surface roughening is particularly important when preparing slopes for hydroseeding. b) Lime and fertilize. Organic fertilizer shall be utilized in areas within the 100-foot buffer zone to a wetland resource area. c) Mulch the seedings with straw applied at the rate of 1/2 tons per acre. Anchor the mulch with erosion control netting or fabric on sloping areas. Amoco supergro or equivalent should be utilized. Best Management Practices Operation and Maintenance Plan MCG Project No. 3908, 335 Willow Street, North Andover, Massachusetts July 29, 2020—Page 7 of 9 j The developer and site general contractor wilt comply with the E.P.A.'s Final General Permit for Construction De-watering Discharges, (N.P.D.E.S., Section 402 and 40 C.F.R. 122.26(b) (14) (x). Inspection/Maintenance: Operator personnel must inspect the construction site at least once every 14 calendar days and within 24 hours of a storm event of 1/2-inch or greater. The applicant shall be responsible to secure the services of a design professional or similar professional (inspector) on an on-going basis throughout all phases of the project. Refer to the Inspection/Maintenance Requirements presented earlier in the 'Structural and Stabilization Practices." The inspector should review the erosion and sediment controls with respect to the following: • Whether or not the measure was installed/performed correctly. = Whether or not there has been damage to the measure since it was installed or performed. • What should be done to correct any problems with the measure, The inspector should document the findings and should request the required maintenance or repair for the pollution prevention measures when the inspector finds that it is necessary for the measure to be effective. The inspector should notify the appropriate person to make the required changes. It is essential that the inspector document the inspection of the pollution prevention measures. These records will be used to request maintenance and repair and to prove that the inspection and maintenance were performed. The forms list each of the measures to be inspected on the site, the inspector's name, the date of the inspection, the condition of the measure/area inspected, maintenance or repair performed and any changes which should be made to the Operation and Maintenance Plan to control or eliminate unforeseen pollution of storm water. Best Management Practices Operation and Maintenance Plan MCG Project No.3908, 335 Willow Street, North Andover, Massachusetts July 29, 2020-Page 9 of 9 1 i �i II I �I APPENDIX F: LONG TERM BEST MANAGEMENT PRACTICES O&M PLAN I Long Term Stormwater Best Management Practices Operation and Maintenance Plan for 335 Willow Street North Andover Massachusetts July 29, 2020 The following operation and maintenance plan has been provided to satisfy the requirements of Standard 9 of the Mass DEP Stormwater Management Handbook associated with development of the site and associated infrastructure. The success of the Stormwater Management Plan depends on the proper implementation, operation and maintenance of several management components. The following procedures shall be implemented to ensure success of the Stormwater Management Plan: 1. The contractor shall comply with the details of construction of the site as shown on the approved plans. 2. The stormwater management system shall be inspected and maintained as indicated below. 3. Effective erosion control measurers during and after construction shall be maintained until a stable turf is established on all altered areas. 4. A Stormwater Management Maintenance Log is included at the end of this Appendix. Basic Information Stormwater Management System Owner: Muffin 3X, LLC 351 Willow St, North Andover, MA 01845 P:(978) 683-1414 North Andover Engineering Department: 384 Osgood Street North Andover, MA 01845 P: (978) 685-0950 North Andover Planning Board: Town Hall 120 Main Street North Andover, MA 01845 P: (978) 688-9535 North Andover Conservation Commission: Town Hall 120 Main Street North Andover, MA 01845 P: (978) 688-9530 Long Term Stormwater Best Management Practices Operation &Maintenance Plan 335 Willow Street, North Andover, Massachusetts July 29, 2020—Page 1 of 4 Long-Term Pollution Prevention Plan (LTPPP) _Vegetated Areas: Immediately after construction, monitoring of the erosion control systems shall occur until establishment of natural vegetation. Afterwards, vegetated areas shall be maintained as such, Vegetation shall be replaced as necessary to ensure proper stabilization of the site. Cost: Included with annual landscaping budget. Consult with local landscape contractors. Paved Areas: Sweepers shall sweep paved areas periodically during dry weather to remove excess sediments and to reduce the amount of sediments that the drainage system shall have to remove from the runoff. The sweeping shall be conducted primarily between March 15th and November 15th. Special attention should be made to sweeping paved surfaces in March and April before spring rains wash residual sand into the drainage system. Cost: Consult with local landscaping companies for associated costs if necessary. Salt used for de-icing on the roadway during winter months shall be limited as much as possible as this will reduce the need for removal and treatment. Sand containing the minimum amount of calcium chloride (or approved equivalent) needed for handling may be applied as part of the routine winter maintenance activities. Subsurface Chamber System: The subsurface chamber system shall be monitored annually to ensure that it is draining properly. The outlet control structure shall be checked for debris accumulation twice per year, in the spring and fall. In the case that water remains in the system for greater than three (3) days after a storm event, an inspection is warranted and necessary maintenance or repairs should be addressed as necessary. Confirm that the orifices and outlet pipe in the outlet control structure is not obstructed by debris. The inspections shall be conducted by qualified personnel. Cost: Consult with local landscaping companies for associated costs if necessary. Public Safety Concerns: Manhole covers or inspection port covers shall not be left open and unattended at any time during inspection, cleaning or otherwise. Broken covers or frames shall be replaced immediately. At no time shall any person enter the subsurface structure unless measures have been taken to ensure safe access in accordance with OSHA enclosed space regulations. Debris& Litter: All debris and litter shall be removed from the roadway and parking lots as necessary to prevent migration into the drainage system. Pesticides, Herbicides, and Fertilizers: Pesticides and herbicides shall be used sparingly. Fertilizers shall be restricted to the use of organic fertilizers only. All fertilizers, herbicides, pesticides, sand and salt for deicing and the like shall be stored in dry area that is protected from weather. Cost: Included in the routine landscaping maintenance schedule. The Owner shall consult local landscaping contractors for details. Long Term Stormwater Best Management Practices Operation &Maintenance Plan 335 Willow Street, North Andover, Massachusetts July 29,2020--Page 3 of 4 I APPENDIX G; ILLICIT DISCHARGE STATEMENT i Illicit Discharge Compliance Statement I, John M. Morin,�P.E., hereby notify the North Andover Planning Board & Conservation Commission that I have not witnessed, nor am aware of any existing illicit discharges at the site known as 335 Willow Street in North Andover, Massachusetts. I also hereby certify that the development of said property as illustrated on the final plans entitled "Site Redevelopment Plan of Land in North Andover, Massachusetts, 335 Willow Street," prepared by The Morin-Cameron Group, Inc. dated July 29, 2020 and as revised and approved by the North Andover Planning Board & Conservation Commission and maintenance thereof in accordance with the "Construction Phase Best Management Practices Plan" and "Long-Term Pollution Prevention Plan" prepared by The Morin- Cameron Group, lnc dated July 29, 2020 and as revised and approved by the North Andover Planning Board & Conservation Commission will not create any new illicit discharges. There is no warranty implied regarding future illicit discharges that may occur as a result of improper construction or maintenance of the stormwater management system or unforeseen accidents. Name: John M. Morin, P.E. Company: The Morin-Cameron Group, Inc. Title: Owner's Representative Signature: ' ins M M_tr_ , Date: 1-71 Zcj 12OZO i I I! I APPENDIX H: SOIL SUITABILITY ASSESSMENT TP20-4 DEEP OBSERVATION HOLE 335 Willow Street North Andover Massachusetts Date: February 06 2020 Time: 11:01 Weather: Overcast, —35-40°F,East wind, light rain Landscape: Upland Landform: Kame terrace Position on landscape: Summit/tread Slope aspect: Easter l Slope(%): 00- 01% Slope complexity: Simple Land Cover: Grass lawn Property line: 10'feet Drainage way: 50'feet Drinking water well: 100'feet Abutting septic system: 50'feet Wetlands: 100'feet Public water supply reservoir: 400'feet Tributary to reservoir: 200'feet SOIL PROFILE ► TP20-4 Depth below Soil Soil Texture Soil Color Redoxomorphic Consistence,grade,size,structure,grain size,soil moisture state, land surface Horizon/ (USDA/NRCS) (Munsell) Features/ roots,Horizon boundary,clasts,stratification,artifacts,restrictive (inches) Layer ESHGWT features,etc. Very friable;moderate-grade fine to medium sub-angular granular QQ" QS" Sand Loam 10YR 3/2 structure;somewhat cohesive;fine grained mineral content;damp Ap y none observed matrix;non-sticky;non plastic;many fine grass roots,free of very darts grayish brown clasts;clear wavy boundary. Very friable;weals-grade,fine,sub-angular blocky structure; somewhat cohesive;mixed medium to mostly fine-grained mineral 1 OYR 5/6 none observed content;damp matrix;non-sticky;non-plastic;few fine roots; 05" 13" B Sandy Loam approximately 05%sub-angular to sub-rounded gravel content of w yellowish mixed lithology;difHise wavy boundary. brown Friable to firm;fine-to-medium,angular to sub-angular platy and 54" blocky structure;mixed fine-to-coarsc grained sand;crudely stratified;damp matrix;—15%sub-angular to sub-rounded gravel 13" 100" 2Cd Sandy Loam 2,5Y5/3 (c,2,d) and-�05%sub-angular to sub-rounded cobble content of mixed gravelly light olive 5YR 5/8 lithology;slightly silty;non-sticky;non-plastic;somewhat brown 10YR 7/1 compact matrix;clasts tightly bound in matrix;redoximorphic high and low chroma colors dispersed within matrix below 54";no apparent water observed;no bedrock refusal at test hole depth. i Depth to bedrock: >100" seasonal High Groundwater Table: 54" Apparent water table: 5 MCG Project#3908 SOIL SUITABILITY ASSESSMENT REPORT COMMONWEALTH OF MAS SACHUSETTS NORTH ANDOVER, MASSACHUSETTS SOIL EVALUATION FOR DESIGN OF ON-SITE STORMWATER DRAINAGE CONTROL SITE INFORMATION Street Address: 335 Willow Street Town:North Andover State: Massachusetts Zip Code: 01845 County: Essex Land Use: Commercial-light industrial Latitude: —421 39'27"N Longitude: ---71°06' 51"W Elevation: —245'to 250' PUBLISHED SOIL DATA AND MAP UNIT DESCRIPTION Physiographic Division:Appalachian Highlands Physio.Province:New England Physio. Section: Seaboard lowland section Soil survey area:Essex County,Massachusetts,Northern Part Series name: 311B—Woodbridge F'SL,00-08%slopes Order: Inceptisol Suborder:Udepts Family: Coarse-loamy mixed, active, mesic,Aquie Dystr€adepts Soil moisture regime. Udic Soil temperature regime:Mesic Depth to restrictive feature:None Soil hydric or upland: Upland Average depth to water table: > 80" Runoff class:Negligible Frequency of flooding None Frequency of ponding:None Available water capacity: low ---3.0" Drainage Class: Moderately well drained Hydrologic Soil Group: C/D Ksat:Low to moderate 0.00—0.14 in/lrr Soil limitations: Low to moderate permeability, compact substratum, shallow seasonal groundwater table WETLAND AREA&USGS WELL MEASUREMENTS National Wetland Inventory Map:NA Wetlands Conservancy Program:NA Bordering vegetative wetland:NA Current Water Resource Condition(USGS):Well Site#4234010711093801,MA-XMW 78 Wilmington,MA Well com leted in Sand and gravel aquifers and ice-contact deposits,including kames and eskers. Well depth: 12.00 feet Borehole depth: 12.00 feet Land surface altitude: 95.00 feet above NGVD29 Most recent data value:7.26'on 02/06/2020(depth below land surface). Range:Normal SURFICIAL GEOLOGY: Surficial Geology: Qp-m: Early Wisconsin glacial-stage Around moraine--Dense subglacial lodgment till deposits. Geologic parent material: Coarse-loamy lodgment till Geomorphic landform: Drumlinoid ridge Slope aspect:North-Northwest Landform position(2D): Shoulder/summit Landform position(3D): Side slope Slope gradient: —0-10% Down slope shape: Linear Across slope shape: Convex Slope complexity: Simple Bedrock outcropping in vicinity:None observed Glacial erratics in vicinity:None observed Bedrock Type: :Andover Granite,, (Silurian or Ordovician)Light to medium grr foliated,medium-to coarse-grained muscovite-biotite rag nite. J MCG Project#3908 I TP20- 1 DEEP OBSERVATION HOLE 335 Willow Street North Andover Massachusetts Date: February 06,2020 Time: 09:46 Weather: Overcast —35-40°F East wind light gain Landscape: Upland Landform; Katne terrace Position on landscape: Summit/tread Slope aspect: Easterly Slope(%): 00- 0 1% Slope complexity: Simple Land Cover; Grass lawn Property line: 10'feet Drainage way: 50' feet Drinking water well: 100'feet Abutting septic system: 50'feet Wetlands: 100'feet Public water supply reservoir: 400"feet Tributary to reservoir: 200'feet SOIL PROFILE ► TP20-I Depth below Soil Soil Texture Soil Color Redoxomorphic Consistence,grade,size,structure,grain size,soil moisture state, land surface Horizon/ (USDA1NRCS) (Munsell) Features/ roots,horizon boundary,clasts,stratification,artifacts,restrictive (inches) Layer ESHGWT features,etc. Very friable;moderate-grade fine to medium sub-angular granular QQ" �6" Sandy Loam 10YR 312 structure;somewhat cohesive;fine grained mineral content;damp > A p an y none observed matrix;non-sticky;non-plastic,many fine grass roots,free of very dark grayish brown clasts;clear wavy boundary. Very friable;weak-grade,fine,sub-angular blocky structure; somewhat cohesive;mixed medium to mostly fine-grained mineral content;damp matrix;non-sticky;non-plastic,few fine roots; Q6" 1 Q" B Sandy Loatn 1 OYR 5/6 none observed approximately 05%sub-angular to sub-rounded gravel eontent of �v yellowish brown mixed lithology;diffuse wavy boundary. Friable to firm;fine-to-medium,angular to sub-angular platy and 58" blocky structure;mixed fine-to-coarse grained sand;crudely Sand Loam 2,SY5/3 (c,2,d} stratified;damp matrix;—15%sub-angular to sub-rounded gravel 10" —+ 111" 2Cd gravelly light olive SYR 5I8 and—05%sub-angular to sub-rounded cobble content of mixed brown lithology;slightly silty;non-sticky;non-plastic;somewhat 1OYR 7/1 compact matrix;clasts tightly bound in matrix;redoximorphic high and low chrome colors dispersed within matrix below 58";no apparent water observed;no bedrock refusal at test hole depth. Depth to bedrock: >111" Seasonal High Groundwater Table: 558" Apparent water table: 2 MCG Project#3908 TP20-2 DEEP OBSERVATION HOLE 335 Willow Street, North Andover, Massachusetts Date: February 06, 2020 Time: 10:17 Weather: Overcast —35-401F East wind light rain Landscape: Upland Landform: Kame terrace Position on landscape: Summit/tread Slope aspect: Easterl Slope(%): 00- 01% Slope complexity: Simple Land Covet: Grass lawn Property line: 10'feet Drainage way: 50'feet Drinking water well: 100'feet Abutting septic system: 50"feet Wetlands: 100'feet Public water supply reservoir: 400'feet Tributary to reservoir: 200'feet SOIL PROFILE ► TP20-2 Depth below Soil Soil Texture Soil Color Redoxomorphic Consistence,grade,size,structure,grain size,so!]moisture state, land surface Horizon/ (USDA/NRCS) (Mansell) Features/ roots,horizon boundary,clasts,stratification,artifacts,restrictive (inches) Layer FSHGWT features,etc. Very friable;moderate-grade fine to anedium sub-angular granular 00" -j 07" SandyLoam 1 OYR 3/2 structure;somewhat cohesive,fine grained mineral content;damp Ap vary dark none observed matrix;non-sticky;non-plastic;many fine grass roots,free of grayish brown clasts;clear wavy boundary. Fill material,friable,structurless;mixed line-to-medium grained mineral content;non-deleterious material;brick,concrete,organics a']" 23" L` Sandy Loam 2,5Y 3/1 none observed and stone mixed within matrix;diffuse wavy boundary Mixture very dark gray Friable to firm;fine-to-medium,angular to sub-angular platy and 57" blocky structure;mixed fine-to-coarse grained sand;crudely stratified;damp matrix;—15%sub-angular to sub-rounded gravel 23" 100" 2Cd Sandy Loaln 2.SY5/3 (e�2�d) and—05%sub-angular to sub-rounded cobble content of mixed gravelly light olive 5YR 5/8 lithology;slightly silty;non-sticky;non-plastic;somewhat brown I OYR 7/1 compact matrix;clasts tightly bound in matrix;redoximorphic high and low chroma colors dispersed within matrix below 57';no apparent water observed;no bedrock refusal at test hole depth. Depth to bedrock: >100" Seasonal High Groundwater Table: 57" Apparent water table: _ 3 MCG Project#3908 i TP20-3 DEEP OBSERVATION HOLE 335 Willow Street North Andover Massachusetts Date: February 06,2020 Time: 10:35 Weather: Overcast —35-40°F East wind light rain Landscape: Upland Landform: Kame terrace Position on landscape: Summit/tread Slope aspect: Easterly Slope(%): 00- 01% Slope complexity: Stele Land Cover: Grass lawn Property line: 10'feet Drainage way: 50'feet Drinking water well: 100*feet Abutting septic system: 50'feet Wetlands: 100'feet Public water supply reservoir: 400'feet Tributary to reservoir: 200'feet SOIL PROFILE P TP20-3 Depth below Soil Soil Texture Soil Color Redoxomorphic Consistence,grade,size,structure,grain size,soil moisture state, land surface Horizon/ (USDA/NRCS) (Mansell) Features/ roots,horizon boundary,clasts,stratification,artifacts,restrictive (inches) Layer ESHGWT features,etc. Very friable;moderate-grade fine to medium sub-angular granular �0" QS" Sand Loatn 1 OYR 3/2 structure;somewhat cohesive;fine grained mineral content;damp Ap y none observed matrix.;non-sticky non-plastic;many fine grass roots,free of very dark grayish brown clasts;clear wavy boundary. Very friable;weak-grade,fine,sub-angular blocky structure; somewhat cohesive;mixed medium to mostly fine-grained mineral content;damp matrix;non-sticky;non-plastic;few fine roots; p$" ZQ" B Sandy Loam 1 OYR 5/6 none observed approximately 05%sub-angular to sub-rounded gravel content of w yellowish mixed lithology;diffuse wavy boundary. brown Friable to firm;fine-to-medium,angular to sub-angular platy and 54" blocky structure;mixed fine-to-coarse grained sand;crudely Sandy Loam 2.5Y5/3 (c,2,d) stratified;damp matrix;--15%sub-angular to sub-rounded gravel 20" 100" 2Cd and—05%sub-angular to sub-rounded cobble content of mixed gravelly fight olive 5YR 5/8 lithology;slightly silty;non-sticky;non-plastic;somewhat brown 10YR 7/1 compact matrix;clasts tightly bound in matrix;redoximorphic high and low chroma colors dispersed within matrix below 54";no apparent water observed;no bedrock refusal at test hole depth. Depth to bedrock: ?100" Seasonal High Groundwater Table; 54" Apparent water table: 4 MCG Project#3908 TP20-4 DEEP OBSERVATION HOLE 335 Willow Street, North Andover, Massachusetts Date: February 06 2020 Time: 11:01 Weather: Overcast, 35-40' ,East„wind, light rain Landscape: Upland Landfoim: Kame terrace Position on landscape: Summit/tread Slope aspect: Easterly Slope(%): 00- 01% Slope complexity: Simple Land Covet: Grass lawn Property line: 10'feet Drainage way: 50'feet Drinking water well: 100'feet Abutting septic system: 50'feet Wetlands: 100'feet Public water supply reservoir: 400'feet Tributary to reservoir: 200'feet I SOIL PROFILE ► TP20-4 Depth below Soil Soil Texture Soil Color Redoxomorphic Consistence,grade,size,structure,grain size,soil moisture state, land surface Horizon/ (USDAINRCS) (Munsell) Features/ roots,horizon boundary,clasts,stratification,artifacts,restrictive (inches) Layer FSHGWT features,etc. Very friable;moderate-grade fine to medium sub-angular granular 00" —� QS" Sandy Laatn 10YR 3/2 structure;somewhat cohesive;fine grained mineral content;damp Ap an y none observed matrix;non-sticky;non-plastic;man fine grass roots free of very dark � k3', p � Y grayish brown clasts;clear wavy boundary. Very friable;weak-grade,fine,sub-angular blocky structure; somewhat cohesive;mixed medium to mostly fine-grained mineral 5' " l OYR 5/6 none observed content;damp matrix;non-sticky;non-plastic;few fine roots; '. QS 13 B Sandy Loam approximately 05%sub-angular to sub-rounded gravel content of w yellowish mixed lithology;diffuse wavy boundary. brown Friable to firm;finc-to-medium,angular to sub-angular platy and 54„ blocky structure;mixed fine-to-coarse grained sand;crudely 13 100 Sandy Loam 2,5Y5/3 (C 2 d) stratified;damp matrix;- 15%sub-angular to sub-rounded gravel 3� ' » 2Cd ' ' and---05%sub-angular to sub-rounded cobble content of mixed gravelly light olive SYR 5/8 lithology;slightly silty;non-sticky;non-plastic;somewhat brown )OYR7/1 compact matrix;clasts tightly bound in matrix;redoximorphic high and low chroma colors dispersed within matrix below 54';no apparent water observed;no bedrock refusal at test hole depth. Depth to bedrock: >100" Seasonal High Groundwater Table: 54" Apparent water table: 5 MCG Project#3908