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Stormwater Report - 250 CLARK STREET 2/19/2013
tlN1V 6X MANN, y P.C. COUNSELLORS AT LAW Ms. Judith Tymon, Town Planner Town of North Andover Planning Department 1600 Osgood Street North Andover, MA 01845 RE: 250 Clark Street, North Andover — Flight Landata, Inc. Dear Ms. Tymon: JILL ELMSTROM MANNt* KURT P. MANNt* MELISSA GNOZA OGDENt tAdmitted to practice in Massachusetts 'Admitted to practice in New York February 19, 2013 Enclosed please find two hard copies of the Stormwater Report, along with a disk of this report and the special permit application in connection with the above matter. Please feel free to call should you need anything further in this regard. Very truly yours, MANN & MANN, P.C. �.Wu��J "�. 4a net t Koehle /jkk enclosures 2012- 51Floreme — FGD "' '"tt" "` -- - kurt@mann c com Middleton, Massachuses 01949 p Telephone: 978 - 762 -6238 melissa@mannpc.com Facsimile: 978 - 762 -6434 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report 250 Cio y- stY141�, Wo, AndovcrI MA. F- ighk I.�►hd�, ,�isc— A. Introduction Important: A Stormwater Report must be submitted with the Notice of Intent permit application to document When filling out compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for forms on the the Stormwater Report which should provide more substantive and detailed information) but is offered computer, use p ( p only the tab key here as a tool to help the applicant organize their Stormwater Management documentation for their to move your Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, cursor - do not the Stormwater Report must contain the engineering computations and supporting information set forth in use the return key. Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. •a 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. Plans are required to show existing and proposed conditions, identify all wetland resource areas, NRCS 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. 2 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. swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 1 of 8 Massachusetts 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 PETER M. fs BLAISDELL, J S I` s CIVIL r `, No. 41613 Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? / ` - New development ( L = ��. (�5"ci DU; 11%k5 w'1 t bt �ASkfW_ d ❑ Redevelopment \ ^'o", onto- 4V%0-4- �7'�'A� 11 hJLS 25 30 s• �• OF PAVLMt11i' ) ol ❑ Mix of New Development and Redevelopment swcheck.doc • 04101/08 Stormwater Report Checklist • Page 2 of 8 L11, Massachusetts 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: X No disturbance to any Wetland Resource Areas ❑ Site Design Practices (e.g. clustered development, reduced frontage setbacks) ❑ Reduced Impervious Area (Redevelopment Only) ❑ 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 Bioretention Cells (includes Rain Gardens) ❑ Constructed Stormwater Wetlands (includes Gravel Wetlands designs) ❑ Treebox Filter ❑ Water Quality Swale ❑ Grass Channel ❑ Green Roof �+ ® Other (describe): - a flhra�M 19r 9 Standard 1: No New Untreated Discharges 0 No new untreated discharges gg Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth DO Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included. swcheck.doc • 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. ,I Sizing the infiltration, BMPs is based on the following method: Check the method used. K 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. OM Atw "OS-cd pavew^.cnIr is �r � �o.� 1-�^p h► ku '!�''� a 's 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. Wr 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% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. swcheck.doc • 04/01/08 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. A 4j ❑ 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: �GWNVIV�' ❑ is within the Zone II 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. swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 5 of 8 Massachusetts 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: ❑ Th '/" r 1" Water Quality 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 party 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 5: 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 bioretention area, a sand filter or equivalent. Standard 6: Critical Areas �1, A . ❑ 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. swcheck.doc • 04/01708 Stormwater Report Checklist • Page 6 of 8 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 N• � extent practicable ❑ The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a: ❑ Limited Project �,cl�tl ❑ 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. { Stormwater Report Chec Massachusetts Department of Environmental Protection Bureau 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 59 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 9 Operation and Maintenance Log Form. Cstc Gl+*C" The responsible party is not the owner of the parcel where the BMP is located and the Stormwater Report includes the following submissions: L.SG� 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 AS4wfftrA 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 R The Long -Term Pollution Prevention Plan includes measures to prevent illicit discharges; 9 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. swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 8 of 8 Project No. NAND -0020 Prepared for: KEYW Corporation (Flight Landata, Inc.) 250 Clark Street North Andover, MA 01854 978 - 682 -7767 (Ph) 978 - 682 -6735 (Fax) Comparative Drainage Analysis Flight Landata 250 Clark Street North Andover, MA 01845 February 7, 2013 I ;WILLIAMS SPARAGES T S 191 S. Main Street, Suite 103 Middleton, MA 01949 Office Tel: 978 - 539 -8088 Fax: 978 - 767 -8579 www.wsengineers.com Comparative Drainage Analysis Flight Landata 250 Clark Street North Andover, Massachusetts Purpose: February 7, 2013 The purpose of this analysis is to compare the approved and the proposed watershed conditions by analyzing the surface runoff rates to the limit of the watershed analysis shown on the accompanying watershed maps. The results of which are presented on the summary table that follows. Introduction: The project is located at 250 Clark Street found within the Lawrence Municipal Airport complex. The land is owned by the City Lawrence and is managed by an organization known as the Lawrence Airport commission. The property is accessed from Clark Street via Holt Road which connects then with Osgood Street (Route 125). The premises currently is currently occupied by an existing 9,525 s.f. commercial building, pavement & walkways equaling approximately 30,350 s.f., lawn, woods, wetlands and other landscaped areas. The proposal is to construct a new 9,680 s.f. building to be used for Hangar & Office Space, a new septic system, an additional 19 paved parking spaces to accommodate the addition, walkways and two (2) rain gardens for stormwater treatment from the new paved areas and portions of the roof area. It should be noted that there are no proposed disturbances to the existing wetland resource areas located adjacent to the project. Existing Condition Soils Analysis: In order to model the runoff parameters for both the existing and proposed watershed parameters, the parent soils on site were mapped using the Web Soil Survey (WSS) made available on the United States Department of Agriculture (USDA) National Resources Conservation Service (NRCS) website. The WSS provides vital soil data and information such as Hydrologic Soil Group (HSG) which is then input into a mathematical model to generate runoff curve numbers. The user inputs the soil cover type as well as the hydrologic soil group to generate a weighted curve number (CN) and also uses the topography of the land to generate a time of concentration (Tc) from which the stormwater runoff rate as well as volume may be calculated for a certain watershed for comparison. The soils present on site are Urban Land, Paxton fine sandy loam and Ridgebury fine sandy loam. The Paxton and Ridgebury soils both have hydrologic soil groups (HSG) of "C; however, the Urban Land does not have one assigned to it by the NRCS. However, for the comparative purposes of this analysis we have assumed that its HSG is also "C. Comparative Drainage Analysis 250 Clark Street, North Andover, MA February 7, 2013 Stormwater Modeling Methodology: The mathematical model used in this analysis was provided using the HydroCAD 9.10 Version developed by HydroCAD Software Solutions LLC. HydroCAD is a program that is used to model the hydrology and hydraulics of stormwater runoff and is based largely on programs and techniques developed by the Soil Conservation Service (SCS) now known as the NRCS, specifically TR -20 and TR -55 as well as other hydraulic calculation methods. HydroCAD allows the user, for a given rainfall event, to generate runoff hydrographs for single or multiple watersheds and is used to determine if a given drainage system is adequate under the desired conditions as well as to predict flooding or other impacts at specified locations such as erosion. In this analysis a 24 -hour Type III distribution for using the Rainfall Data found on page 19 of the North Andover Stormwater Management and Erosion Control Regulations was used. Four (4) design storm events were analyzed and the results presented in the tables that follow for the two (2) year, ten (10) year, twenty -five (25) and one - hundred (100) year storm events for comparison. Existing Condition Watershed: The point of comparison selected is limit of the watershed analysis which has been delineated along the proposed lease area as well as the existing limit of disturbance in order to have an equal area to compare with the proposed condition. Using the methods described in the stormwater modeling explanation above, runoff curve numbers and times of concentration were generated for each watershed for the existing condition to be used for comparison with the proposed condition described below. A schematic of the mathematical model as well as the results of the calculations for the 2 year, 10 year and 100 year, Type III, 24 -hour storm events are included in this report. Proposed Condition Watershed: In order to mitigate the peak rates of runoff for the 4 design storms we are proposing to construct two (2) rain gardens that will treat the stormwater runoff, provide some infiltration of the runoff into the ground. The rain gardens were chosen as the best solution to this site as it is a low impact development alternative and will not require the installation of drainage structures and pipes which require more extensive maintenance schedules. Using the methods described above, runoff curve numbers and times of concentration were generated for each watershed for the existing condition to be used for comparison with the proposed condition described below. A schematic of the mathematical model as well as the results of the calculations for the 2 year, 10 year and 100 year, Type III, 24 -hour storm events are included in this report. 2 Comparative Drainage Analysis 250 Clark Street, North Andover, MA February 7, 2013 Conclusion: As can be seen by examining the following summary table and the performance summary of the rain gardens, the design will be effective for mitigating the peak flow rates of runoff from the limit of the watershed analysis for the 2, 10, 25, & 100 year storm events. Further, a reduction in the peak rate of runoff is expected due to the detention of stormwater runoff and groundwater recharge opportunity available within the rain gardens. According to the mathematical model, there will be a slight decrease in the amount of runoff volume within the limit of the watershed analysis for the 2, 10, 25 and 100 year storms as shown on the table below. Total Peak Rate of Runoff Comparison Table Description 24 hour Type III Existing Peak Proposed Peak Storm Event Rate of Runoff Rate of Runoff (year) Q cfs. Q) cfs. Flow leaving the 2 (3.2 inch) 3.8 3.0 limit of watershed 10 (4.8 inch) 6.8 6.0 analysis 25 (6.0 inch) 9.1 7.9 Link 119L 100 (8.6 inch) 14.1 12.1 Total Runoff Volume Comparison Table Description 24 hour Type III Existing Proposed Storm Event Volume Volume (year) Acre -ft Acre -ft Flow leaving the 2 (3.2 inch) 0.291 0.278 limit of watershed 10 (4.8 inch) 0.527 0.519 analysis 25 (6.0 inch) 0.711 0.706 Link 119L 100 (8.6 inch) 1.123 1.121 '43 Comparative Drainage Analysis 250 Clark Street, North Andover, MA February 7, 2013 Proposed Rain Garden 1 Performance Table HydroCAD 117P Top of berm = 133.75 ft 12' wide stone spillway @ 133.25 Bottom of berm = 133.00 ft 24 hour Type III Storm Event (YR) Peak Rate of Runoff In (Qin) cfs. Peak Rate of Runoff Out (Q) cfs. Peak Water Level (W.L.) ft *Exfiltration (discarded) 12'wide spillway 2 1.1 0.02 0.89 133.35 10 1.7 0.02 1.68 133.40 25 2.2 0.02 2.19 133.43 100 3.3 0.02 3.31 133.48 *The design infiltration rate of 0.27 inches per hour for NRCS Hydrologic Soil Group "C" is as shown on Table 2 -1 Infiltration Rates for Various Soil Textures found in the Hydrology Handbook for Conservation Commissioners, March 2002. 4 Comparative Drainage Analysis 250 Clark Street, North Andover, MA February 7, 2013 Proposed Rain Garden 2 Performance Table HydroCAD 120P Top of berm = 133.75 ft 6' wide stone spillway @ 133.25 Bottom of berm = 133.00 ft 24 hour Type III Storm Event (YR) Peak Rate of Runoff In (Qin) cfs. Peak Rate of Runoff Out (Q) cfs. Peak Water Level (W.L.) ft *Exfiltration (discarded) 6'wide spillway 2 0.4 0.01 0.32 133.33 10 0.7 0.01 0.61 133.37 25 0.9 0.01 0.84 133.40 100 1.4 0.01 1.35 133.46 *The design infiltration rate of 0.27 inches per hour for NRCS Hydrologic Soil Group "C" is as shown on Table 2 -1 Infiltration Rates for Various Soil Textures found in the Hydrology Handbook for Conservation Commissioners, March 2002. 5 ' w V, U J J 5 4- ■- U) C O O M (A L L N cu N O .4) 'L c U OL i.� V CL 0 N O }, -0 C) OQ O 0- O7 cl U 0 J' t�♦♦�^^ V� W FE Existing Condition Watershed Analysis - 250 Clark Street, North Andover, MA existing_r Prepared by Microsoft Printed 2/7/2013 HydroCADO 9.10 s/n 06611 © 2010 HydroCAD Software Solutions LLC Page 1 Area Listing (all nodes) Area CN Description (sq -ft) (subcatchment- numbers) 6,074 70 Woods, Good, HSG C (116S) 40,506 74 >75% Grass cover, Good, HSG C (116S) 30,350 98 Unconnected pavement, HSG C (116S) 9,525 98 Unconnected roofs, HSG C (116S) 86,455 TOTAL AREA Existing Condition Watershed Analysis - 250 Clark Street, North Andover, MA existing_r Prepared by Microsoft Printed 2/7/2013 HydroCADO 9.10 s/n 06611 © 2010 HydroCAD Software Solutions LLC Page 2 Soil Listing (all nodes) Area Soil Subcatchment (sq -ft) Group Numbers 0 HSG A 0 HSG B 86,455 HSG C 116S 0 HSG D 0 Other 86,455 TOTAL AREA Existing Condition Watershed Analysis - 250 Clark Street, North Andover, MA existing_r Type 111 24 -hr 2 yr Rainfall = 3.20" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 @2010 HydroCAD Software Solutions LLC Page 3 Time span =0.00 -40.00 hrs, dt =0.05 hrs, 801 points x 3 Runoff by SCS TR -20 method, UH =SCS Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchment 116S: Existing Runoff Area = 86,455 sf 46.12% Impervious Runoff Depth= 1.76" Flow Length =210' Tc =7.9 min CN =85 Runoff =3.78 cfs 12,663 cf Link 119L: Total Surficial Flow leaving limit of watershed analysis Inflow =3.78 cfs 12,663 cf Primary=3.78 cfs 12,663 cf Total Runoff Area = 86,455 sf Runoff Volume = 12,663 cf Average Runoff Depth = 1.76" 53.88% Pervious = 46,580 sf 46.12% Impervious = 39,875 sf Existing Condition Watershed Analysis - 250 Clark Street, North Andover, MA existing_r Type/// 24 -hr 2 yr Rainfall = 3.20" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 @2010 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 116S: Existing Runoff = 3.78 cfs @ 12.11 hrs, Volume= 12,663 cf, Depth= 1.76" Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -40.00 hrs, dt= 0.05 hrs Type'lll 24 -hr 2 yr Rainfall= 3.20" Area (sf) CN Description 6,074 70 Woods, Good, HSG C 9,525 98 Unconnected roofs, HSG C 30,350 98 Unconnected pavement, HSG C 40,506 74 >75% Grass cover, Good, HSG C 86,455 85 Weighted Average 46,580 53.88% Pervious Area 39,875 Grass: Short n=0.150 P2=3.20" 46.12% Impervious Area 39,875 0.0070 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.5 50 0.0140 0.13 Sheet Flow, Grass: Short n=0.150 P2=3.20" 0.7 70 0.0070 1.70 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.7 90 0.0170 2.10 Shallow Concentrated Flow, Unoaved Kv= 16.1 fns 7.9 210 Total Summary for Link 1191-: Total Surficial Flow leaving limit of watershed analysis Inflow Area = 86,455 sf, 46.12% Impervious, Inflow Depth = 1.76" for 2 yr event Inflow = 3.78 cfs @ 12.11 hrs, Volume= 12,663 cf Primary = 3.78 cfs @ 12.11 hrs, Volume= 12,663 cf, Atten= 0 %, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00 -40.00 hrs, dt= 0.05 hrs Existing Condition Watershed Analysis - 250 Clark Street, North Andover, MA existing_r Type 111 24 -hr 10 yr Rainfall= 4.80" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 @2010 HydroCAD Software Solutions LLC Page 1 Time span =0.00 -40.00 hrs, dt =0.05 hrs, 801 points x 3 Runoff by SCS TR -20 method, UH =SCS Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchment 116S: Existing Runoff Area = 86,455 sf 46.12% Impervious Runoff Depth= 3.18" Flow Length =210' Tc =7.9 min CN =85 Runoff =6.80 cfs 22,937 cf Link 119L: Total Surficial Flow leaving limit of watershed analysis Inflow =6.80 cfs 22,937 cf Primary=6.80 cfs 22,937 cf Total Runoff Area = 86,455 sf Runoff Volume = 22,937 cf Average Runoff Depth = 3.18" 53.88% Pervious = 46,580 sf 46.12% Impervious = 39,875 sf Existing Condition Watershed Analysis - 250 Clark Street, North Andover, MA existing_r Type 111 24 -hr 25 yr Rainfall= 6.00" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 @2010 HydroCAD Software Solutions LLC Page 2 Time span =0.00 -40.00 hrs, dt =0.05 hrs, 801 points x 3 Runoff by SCS TR -20 method, UH =SCS Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchment 116S: Existing Runoff Area = 86,455 sf 46.12% Impervious Runoff Depth= 4.30" Flow Length =210' Tc =7.9 min CN =85 Runoff =9.09 cfs 30,998 cf Link 119L: Total Surficial Flow leaving limit of watershed analysis Inflow =9.09 cfs 30,998 cf Primary=9.09 cfs 30,998 cf Total Runoff Area = 86,455 sf Runoff Volume = 30,998 cf Average Runoff Depth = 4.30" 53.88% Pervious = 46,580 sf 46.12% Impervious = 39,875 sf Existing Condition Watershed Analysis - 250 Clark Street, North Andover, MA existing_r Type /// 24 -hr 100 yr Rainfall= 8.60" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 © 2010 HydroCAD Software Solutions LLC Page 3 Time span =0.00 -40.00 hrs, dt =0.05 hrs, 801 points x 3 Runoff by SCS TR -20 method, UH =SCS Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchment 116S: Existing Runoff Area = 86,455 sf 46.12% Impervious Runoff Depth= 6.79" Flow Length =210' Tc =7.9 min CN =85 Runoff =14.05 cfs 48,944 cf Link 119L: Total Surficial Flow leaving limit of watershed analysis Inflow =14.05 cfs 48,944 cf Primary=14.05 cfs 48,944 cf Total Runoff Area = 86,455 sf Runoff Volume = 48,944 cf Average Runoff Depth = 6.79" 53.88% Pervious = 46,580 sf 46.12% Impervious = 39,875 sf U J J N N o o SIN co N 0,700 N C +) Q L Q'i o cu LL �` �= E o ° C L po W.0 D �� co -v o = p c •` (a N D- p o _ p of LL M c ..� V E_ cif o >, 'E 2 '':^3 c -C VJ -_ > L U ai LL cu 1� ca c" r == c •� J cu Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed_r Prepared by Microsoft Printed 2/7/2013 HydroCADO 9.10 s/n'06611 © 2010 HydroCAD Software Solutions LLC Pagel Area Listing (all nodes) Area CN Description (sq -ft) (subcatchment- numbers) 1,668 70 Woods, Good, HSG C (122S) 33,032 74 >75% Grass cover, Good, HSG C (116S, 121 S, 122S) 32,550 98 Unconnected pavement, HSG C (116S, 121 S, 122S) 19,205 98 Unconnected roofs, HSG C (116S, 122S) 86,455 TOTAL AREA Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed_r Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 @2010 HydroCAD Software Solutions LLC Page 2 Soil Listing (all nodes) Area Soil Subcatchment (sq -ft) Group Numbers 0 HSG A 0 HSG B 86,455 HSG C 116S, 121 S, 122S 0 HSG D 0 Other 86,455 TOTAL AREA Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed_r Type/// 24 -hr 2 yr Rainfall= 3.20" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 @2010 HydroCAD Software Solutions LLC Page 3 Time span =0.00 -40.00 hrs, dt =0.05 hrs, 801 points x 3 Runoff by SCS TR -20 method, UH =SCS Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchment 116S: PR -RG1 Runoff Area = 24,972 sf 70.94% Impervious Runoff Depth= 2.26" Flow Length =230' Tc =15.0 min CN =91 Runoff =1.13 cfs 4,699d Subcatchment 121S: PR -RG2 Runoff Area =7,937 sf 31.47% Impervious Runoff Depth= 1.54" Flow Length =100' Tc =3.5 min CN =82 Runoff =0.35 cfs 1,017d Subcatchment 122S: Remaining Land Runoff Area = 53,546 sf 58.91% Impervious Runoff Depth= 2.00" Flow Length =70' Tc =9.2 min CN =88 Runoff =2.53 cfs 8,911 cf Pond 117P: Rain Garden 1 Peak Elev= 133.35' Storage =1,276 cf Inflow =1.13 cfs 4,699 cf Discarded =0.02 cfs 2,206 cf Primary=0.89 cfs 2,495 cf Outflow =0.92 cfs 4,701 cf Pond 120P: Rain Garden 2 Peak Elev= 133.33' Storage =165 cf Inflow =0.35 cfs 1,017 cf Discarded =0.00 cfs 294 cf Primary=0.32 cfs 723 cf Outflow =0.33 cfs 1,017 cf Link 119L: Total Surficial Flow leaving limit of watershed analysis Inflow =2.99 cfs 12,129 cf Primary=2.99 cfs 12,129 cf Total Runoff Area = 86,455 sf Runoff Volume = 14,628 cf Average Runoff Depth = 2.03" 40.14% Pervious = 34,700 sf 59.86% Impervious = 51,755 sf Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed _r Type 111 24 -hr 2 yr Rainfall= 3.20" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 @2010 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 116S: PR -RG1 Runoff = 1.13 cfs @ 12.20 hrs, Volume= 4,699 cf, Depth= 2.26" Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -40.00 hrs, dt= 0.05 hrs Type III 24 -hr 2 yr Rainfall= 3.20" Area (sf) CN Description 7,821 98 Unconnected roofs, HSG C 9,893 98 Unconnected pavement, HSG C 7,258 74 >75% Grass cover, Good, HSG C 24,972 91 Weighted Average 7,258 29.06% Pervious Area 17,714 70.94% Impervious Area 17,714 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.9 50 0.0025 0.06 Sheet Flow, Grass: Short n= 0.150 P2= 3.20" 1.4 70 0.0025 0.81 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.7 100 0.0120 2.22 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.0 10 0.3300 9.25 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 15.0 230 Total Summary for Subcatchment 121 S: PR -RG2 [49] Hint: Tc <2dt may require smaller dt Runoff = 0.35 cfs @ 12.06 hrs, Volume= 1,017 cf, Depth= 1.54" Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -40.00 hrs, dt= 0.05 hrs Type III 24 -hr 2 yr Rainfall= 3.20" Area (sf) CN Description 2,498 98 Unconnected pavement, HSG C 5,439 74 >75% Grass cover, Good, HSG C 7,937 82 Weighted Average 5,439 68.53% Pervious Area 2,498 31.47% Impervious Area 2,498 100.00% Unconnected Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed_r Type 111 24 -hr 2 yr Rainfall= 3.20" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 @2010 HvdroCAD Software Solutions LLC Page 5 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.0 20 0.0150 0.11 Sheet Flow, 22,003 0.1 20 41.09% Pervious Area 31,543 Grass: Short n= 0.150 P2= 3.20" 0.3 50 0.0160 2.57 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.2 30 0.0200 2.28 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 3.5 100 Total Summary for Subcatchment 122S: Remaining Land Runoff = 2.53 cfs @ 12.13 hrs, Volume= 8,911 cf, Depth= 2.00" Runoff by SCS TR -20 method, UH =SCS, Time Span= 0.00 -40.00 hrs, dt= 0.05 hrs Type III 24 -hr 2 yr Rainfall= 3.20" Area (sf) CN Description 11,384 98 Unconnected roofs, HSG C 20,159 98 Unconnected pavement, HSG C, 20,335 74 >75% Grass cover, Good, HSG C 1,668 70 Woods, Good, HSG C 53,546 88 Weighted Average 22,003 0.1 20 41.09% Pervious Area 31,543 Shallow Concentrated Flow, 58.91% Impervious Area 31,543 Volume= 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.1 50 0.0060 0.09 Sheet Flow, Volume= 4,701 cf, Atten= 19 %, Lag= 7.0 min Discarded = Grass: Short n=0.150 P2=3.20" 0.1 20 0.0200 2.28 Shallow Concentrated Flow, 0.89 cfs @ 12.32 hrs, Volume= Unpaved Kv= 16.1 fps 9.2 70 Total Summary for Pond 117P: Rain Garden 1 Inflow Area = 24,972 sf, 70.94% Impervious, Inflow Depth = 2.26" for 2 yr event Inflow = 1.13 cfs @ 12.20 hrs, Volume= 4,699 cf Outflow = 0.92 cfs @ 12.32 hrs, Volume= 4,701 cf, Atten= 19 %, Lag= 7.0 min Discarded = 0.02 cfs @ 12.32 hrs, Volume= 2,206 cf Primary = 0.89 cfs @ 12.32 hrs, Volume= 2,495 cf Routing by Dyn -Stor -Ind method, Time Span= 0.00 -40.00 hrs, dt= 0.05 hrs / 3 Peak Elev= 133.35'@ 12.32 hrs Surf.Area= 3;924 sf Storage= 1,276 cf Plug -Flow detention time= 206.1 min calculated for 4,695 cf (100% of inflow) Center -of -Mass det. time= 206.9 min ( 1,017.7 - 810.8 ) Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed_r Type 111 24 -hr 2 yr Rainfall= 3.20" Prepared by Microsoft Printed 2/7/2013 HydroCADO 9.10 s/n 06611 © 2010 HydroCAD Software Solutions LLC Page 6 Volume Invert Avail.Storage Storage Description #1 133.00' 2,996 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 133.00 3,523 0 0 133.25 3,701 903 903 133.50 4,270 996 1,899 133.75 4,500 1,096 2,996 Device Routing Invert Outlet Devices #1 Discarded 133.00' 0.270 in /hr Exfiltration over Surface area #2 Primary 133.25' 12.0' long x 8.0' breadth Broad - Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64 2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74 Discarded OutFlow Max =0.02 cfs @ 12.32 hrs HW= 133.35' (Free Discharge) t1= Exfiltration ( Exfiltration Controls 0.02 cfs) Primary OutFlow Max =0.88 cfs @ 12.32 hrs HW= 133.35' TW =0.00' (Dynamic Tailwater) L2= Broad - Crested Rectangular Weir (Weir Controls 0.88 cfs @ 0.76 fps) Summary for Pond 120P: Rain Garden 2 Inflow Area = 7,937 sf, 31.47% Impervious, Inflow Depth = 1.54" for 2 yr event Inflow = 0.35 cfs @ 12.06 hrs, Volume= 1,017 cf Outflow = 0.33 cfs @ 12.09 hrs, Volume= 1,017 cf, Atten= 7 %, Lag= 1.9 min Discarded = 0.00 cfs @ 12.09 hrs, Volume= 294 cf Primary = 0.32 cfs @ 12.09 hrs, Volume= 723 cf Routing by Dyn -Stor -Ind method, Time Span= 0.00 -40.00 hrs, dt= 0.05 hrs / 3 Peak Elev= 133.33'@ 12.09 hrs Surf.Area= 568 sf Storage= 165 cf Plug -Flow detention time= 131.9 min calculated for 1,016 cf (100% of inflow) Center -of -Mass det. time= 132.6 min ( 966.5 - 833.9 ) Volume Invert Avail.Storage Storage Description #1 133.00' 453 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 133.00 450 0 0 133.25 525 122 122 133.75 800 331 453 Device Routing Invert Outlet Devices #1 Discarded 133.00' 0.270 in /hr Exfiltration over Surface area #2 Primary 133.25' 6.0' long x 8.0' breadth Broad - Crested Rectangular Weir Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed_r Type/// 24 -hr 2 yr Rainfall= 3.20" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 © 2010 HydroCAD Software Solutions LLC Page 7 Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.43 2.54 2.70 2.69 2.68 2.68 2.66 2.64 2.64 2.64 2.65 2.65 2.66 2.66 2.68 2.70 2.74 Qiscarded OutFlow Max =0.00 cfs @ 12.09 hrs HW= 133.33' (Free Discharge) '-- 1= Exfiltration (Exfiltration Controls 0.00 cfs) Primary OutFlow Max =0.31 cfs @ 12.09 hrs HW= 133.33' TW =0.00' (Dynamic Tailwater) L2= 13road - Crested Rectangular Weir (Weir Controls 0.31 cfs @ 0.68 fps) Summary for Link 119L: Total Surficial Flow leaving limit of watershed analysis Inflow Area = 86,455 sf, 59.86% Impervious, Inflow Depth = 1.68" for 2 yr event Inflow = 2.99 cfs @ 12.16 hrs, Volume= 12,129 cf Primary = 2.99 cfs @ 12.16 hrs, Volume= 12,129 cf, Atten= 0 %, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00 -40.00 hrs, dt= 0.05 hrs Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed _r Type Ill 24 -hr 10 yr Rainfall= 4.80" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 © 2010 HydroCAD Software Solutions LLC Paae 1 Time span =0.00 -40.00 hrs, dt =0.05 hrs, 801 points x 3. Runoff by SCS TR -20 method, UH =SCS Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchment 116S: PR -RG1 Runoff Area = 24,972 sf 70.94% Impervious Runoff Depth= 3.79" Flow Length =230' Tc =15:0 min CN =91 Runoff =1.85 cfs 7,883 cf Subcatchment 121S: PR -RG2 Runoff Area =7,937 sf 31.47% Impervious Runoff Depth= 2.90" Flow Length =100' Tc =3.5 min CN =82 Runoff =0.66 cfs 1,919 cf Subcatchment 122S: Remaining Land Runoff Area = 53,546 sf 58.91 % Impervious Runoff Depth= 3.48" Flow Length =70' Tc =9.2 min CN =88 Runoff =4.32 cfs 15,525 cf Pond 117P: Rain Garden 1 Peak Elev= 133.40' Storage =1,479 cf Inflow =1.85 cfs 7,883 cf Discarded =0.03 cfs 2,419 cf Primary=1.68 cfs 5,466 cf Outflow =1.70 cfs 7,885 cf Pond 120P: Rain Garden 2 Peak Elev= 133.37' Storage =190 cf Inflow =0.66 cfs 1,919 cf Discarded =0.00 cfs 314 cf Primary=0.62 cfs 1,605 cf Outflow =0.62 cfs 1,919 cf Link 119L: Total Surficial Flow leaving limit of watershed analysis Inflow =6.01 cfs 22,596 cf Primary=6.01 cfs 22,596 cf Total Runoff Area = 86,455 sf Runoff Volume = 25,327 cf Average Runoff Depth = 3.52" 40.14% Pervious = 34,700 sf 59.86% Impervious = 51,755 sf Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed _r Type/// 24 -hr 25 yr Rainfall = 6.00" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 © 2010 HydroCAD Software Solutions LLC Page 2 Time span =0.00 -40.00 hrs, dt =0.05 hrs, 801 points x 3 Runoff by SCS TR -20 method, UH =SCS Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchment 116S: PR -RG1 Runoff Area = 24,972 sf 70.94 % Impervious Runoff Depth= 4.96" Flow Length =230' Tc =15.0 min CN =91 Runoff =2.39 cfs 10,316 cf Subcatchment 121S: PR -RG2 Runoff Area =7,937 sf 31.47% Impervious Runoff Depth= 3.99" Flow Length =100' Tc =3.5 min CN =82 Runoff =0.90 cfs 2,637 cf Subcatchment 122S: Remaining Land Runoff Area= 53,546 sf 58.91% Impervious Runoff Depth= 4.63" Flow Length =70' Tc =9.2 min CN =88 Runoff =5.67 cfs 20,641 cf Pond 117P: Rain Garden 1 Peak Elev= 133.43' Storage =1,598 cf Inflow =2.39 cfs 10,316 cf Discarded =0.03 cfs 2,512 cf Primary=2.19 cfs 7,805 cf Outflow =2.22 cfs 10,317 cf Pond 120P: Rain Garden 2 Peak Elev= 133.40' Storage =207 cf Inflow =0.90 cfs 2,637 cf Discarded =0.00 cfs 326 cf Primary=0.85 cfs 2,311 cf Outflow =0.85 cfs 2,637 cf Link 119L: Total Surficial Flow leaving limit of watershed analysis Inflow--7.93 cfs 30,758 cf Primary=7.93 cfs 30,758 cf Total Runoff Area = 86,455 sf Runoff Volume = 33,595 cf Average Runoff Depth = 4.66" 40.14% Pervious = 34,700 sf 59.86% Impervious = 51,755 sf Proposed Condition Watershed Analysis - 250 Clark Street, North Andover, MA proposed _r Type 111 24 -hr 100 yr Rainfall = 8.60" Prepared by Microsoft Printed 2/7/2013 HydroCAD® 9.10 s/n 06611 © 2010 HydroCAD Software Solutions_LLC Paae 3 Time span =0.00 -40.00 hrs, dt =0.05 hrs, 801 points x 3 Runoff by SCS TR -20 method, UH =SCS Reach routing by Dyn -Stor -Ind method - Pond routing by Dyn -Stor -Ind method Subcatchment 116S: PR -RG1 Runoff Area = 24,972 sf 70.94% Impervious Runoff Depth= 7.52" Flow Length =230' Tc =15.0 min CN =91 Runoff =3.54 cfs 15,644 cf Subcatchment 121S: PR -RG2 Runoff Area =7,937 sf 31.47% Impervious Runoff Depth= 6.43" Flow Length =100' Tc =3.5 min CN =82 Runoff =1.43 cfs 4,254 cf Subcatchment 122S: Remaining Land Runoff Area = 53,546 sf 58.91% Impervious Runoff Depth= 7.16" Flow Length =70' Tc =9.2 min CN =88 Runoff =8.57 cfs 31,929 cf Pond 117P: Rain Garden 1 Peak Elev= 133.48' Storage =1,827 cf Inflow =3.54 cfs 15,644 cf Discarded =0.03 cfs 2,652 cf Primary=3.31 cfs 12,992 cf Outflow =3.33 cfs 15,644 cf Pond 120P: Rain Garden 2 Peak Elev= 133.46' Storage =241 cf Inflow =1.43 cfs 4,254 cf Discarded =0.00 cfs 346 cf Primary=1.35 cfs 3,908 cf Outflow =1.36 cfs 4,254 cf Link 119L: Total Surficial Flow leaving limit of watershed analysis Inflow =12.07 cfs 48,829 cf Primary=12.07 cfs 48,829 cf Total Runoff Area = 86,455 sf Runoff Volume = 51,826 cf Average Runoff Depth = 7.19" 40.14% Pervious = 34,700 sf 59.86 % Impervious = 51,755 sf WILLIAMS SPARAGES ENUNEEAS . PLAWERS . SURVEYORS 191 South Main Street, Suite 103 Middleton, MA 01949 (978) 539-8088 Office www.wsengineers.com T-w: -W, & WILLIAMS SPARAGES MQNMA i FUMERS i SUiVMn T s 191 South Main Street, Suite 103 Middleton, MA 01949 (978) 539 -8088 Office www.wsengineers.com i s _• / / ' .. ° _ ■ A _ 1 r a E m r 0 0 Z 3� L � U d m N O 0 N'O m C Q c0 C O O Z U� N r LU Oo LO (7 N. 0 U) 0 tm O O .D 2 .6.L.iL ..BZ.L etL a N N V ? i0 r io in v v N N V V ..6.L.0 �Oo O v °o m ° h x N m N_ O C N O V O C p N O O cli N m N o. m � 0 0 Z Q .BZ d .LL M d 00 N � m r Co CL T N 3 >,-5 � N W = m 0y cn n 32 m 0 m Z 8 WE O C N O � Z N � C R O ZU N a E m r- 0 Z N ^ �Q N U > O O N � N C Q 0 O �Z O U y x � N !n w -L �U 00 ULO N U) U O O S 0o v 00 N N n_ m m Z 7 N O am O m y O �U m O M Z m v N � N 7 C O O � A � m N A O z C C f6 N R E m L :- �N c�0cy ) m > c-0) t `6 E m°N 3co V Z m v r a) `. C E N m d U O �- N 7 °'O u f4 N 7 �yy Z 0 o 0 _ V m Z - O. C U N N O C N UC U O N 0 O O x E N �Up Q M `I . m m m cC V7 V) U tmp ° t� m m N y .s N N E ca N 0 m 0 ZQ Z cS o °L E Q ao 3 c mE O n c 'aN o O d N U m mnm� E U oZ f0: n. 30cac JCL/ O > c �� m Z o v ai c a N o 03 0 3 U c um> ?E i a m : d � t� � m � y0. om 0 L�t a VH � ? N; 3 a a+ Q W N d � E m > Z � E c aE rID ° w° s m w >° m� ic:° f6 o rnaai c N N ° C L O C N O. T t6 Z N 6 Q Q 0 ° N 0 0 C U O (O n UO J : 7 'C N (C 6 O r- 2- .+ . .° y m ° O O O 12 'O 3 U) a N CD c E rnEw $ N U) v am a� N Z m n 0 M F- . O w E EN a E O lQ U L t-w O 7 NU iE o L E H u o N B a7 N 0 m c m Z N LU ,n O V c � a7 N ° v d p M J Q N p_ N w a N m `7 a p N D I¢ a O m m '5 H N v N ii N N C 'N 8 N N 0 s o FINE] [Ism M A m LL c N N r A (j { Cr O O t 0o v 00 N N n_ m m Z 7 N O am O m y O �U m O M Z m v N � N 7 C O O � A � m N A O z Hydrologic Soil Group —Essex County, Massachusetts, Northern Part Hydrologic Soil Group 250 Clark Street, North Andover, MA Hy�ttr914grc Sops Group- �tl�mary'#�Y Slap �nft ��ss+�x G+oagt�r; l�laa�a�iusetts, No�ialtrt P�lrir �MA606) < Marrrtittzymb�t Mapnitrttm .' s fiat3ti� A�nesii�Jtb:y P�rcentofA01 ` 70A Ridgebury fine sandy loam, 0 to 3 C 3.5 19.4 % percent slopes 3058 Paxton fine sandy loam, 3 to 8 C 8.1 45.2% percent slopes 305C Paxton fine sandy loam, 8 to 15 C 1.0 5.8% percent slopes 602 Urban land 5.3 29.5% Totals for Area of Interest 17.9 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long- duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B /D, and C /D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B /D, or C /D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. USDA am Natural Resources Web Soil Survey 1/17/2013 Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Group —Essex County, Massachusetts, Northern Part Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff.* None Specified Tie -break Rule: Higher 250 Clark Street, North Andover, MA USDA Natural Resources Web Soil Survey 1/17/2013 Conservation Service National Cooperative Soil Survey Page 4 of 4 N O Q. N 0 A3A,, /W VA /+ W U); L O CDO W E N CD N N � Q N 7 t � (i H1 C0 W 3 O r o c O r E� t- VUIL a mc���fi c U a) O E U Z 3 m = °' N c Li. N d N O CCL aa) J d s 0 r rw = r N •C N �O e.. 0 U ou N N m CO) C� 0 W o LL i m >� N .a N o o U m � m x O v cr C � m a m LLN V m aa0 0 o E -- o 0 'a CL m C o- U N C w �o N � O U) e „A a m Go N O Z c 0 :D Q z if 0 m U w N ^O l.L N 3 as 1 O L d N N N Q a+ N V � N � t � 3 0 r r c O o V U LL �.iastra; r A ci N c 0 E Z 0 o m = O fa � O N O C a a� 0 U d t 0 m = w N O N '0 C v O C.1 m w O U N ` N U) � C E E a o ° LL > d >' N � o° CD w -- c `m m LL H U d CL `o E o E- o 0 m � L CL m oc V N C w A w U) 02 N O .a r � � a 1 � c Q OD a) O z cu c 0 0 0 C v a 1"` 11 O d U O 19, EEP w ^U) ii N B 3 ``d^ V/ W v/ O L O N d N Q v .Q N N � Rf 3 � r c O r c� O V0 LL a a� C c U LI. C W s, .n E z 0 c O a� O CL a� 0 d s O C .O N O O V �O V Cr N � Its � a m � C m aN m E E m m G O LL > N l0 0 O V m > m x Q e R m o. m LL N V m M0 o E o E- o 0 a r a m o. U N c A.. � o 2 u0J e N �. 0 = J o 6' 0 0 r N O z c O v Z. co O LO m a m N O CL D m O) (0 3 m C O N N m Q w O O LL 0 m U w Pollution Prevention Plan Potential Sources of Pollution Potential sources of sediment to stormwater runoff: • Clearing and grubbing operations • Grading and site excavation operations • Vehicle tracking • Topsoil stripping and stockpiling • Landscaping operations Potential pollutants and sources, other than sediment, to stormwater runoff: • Combined Staging Area —small fueling activities, minor equipment maintenance and sanitary facilities. • Materials Storage Area — general building materials, solvents, adhesives, paving materials, paints, aggregates, dumpster, etc. • Construction Activity — paving, curb /sidewalk installation, concrete pouring /mortar /stucco, and building construction For all potential construction site pollutants, see Table on the following page. Pesticides (insecticides, Chlorinated hydrocarbons, Herbicides used for noxious fungicides, herbicides, organophosphates, weed control rodenticides) carbamates, arsenic Home construction Fertilizer Nitrogen, phosphorous Newly seeded areas Plaster Calcium sulphate, calcium Home construction Wood preservatives carbonate, sulfuric acid Asphalt Oil, petroleum distillates Streets and roofing Concrete I Limestone, sand, pH, I Curb and gutter, building chromium construction Glue, adhesives Polymers, epoxies Home construction Metal oxides, stoddard Paints solvent, talc, calcium Home construction carbonate, arsenic Stoddard solvent, petroleum Timber pads and Home Wood preservatives distillates, arsenic, copper, chromium construction Hydraulic oil/fluids Mineral oil Leaks or broken hoses from equipment Gasoline Benzene, ethyl benzene, Secondary toluene, xylene, MTBE containment/staging area Diesel Fuel Petroleum distillate, oil & Secondary grease, naphthalene, xylenes containment/staging area Ethylene glycol, propylene Leaks or broken hoses from Antifreeze /coolant glycol, heavy metals f,.,.. --- 1-- a .. � equipment Sanitary toilets I Bacteria, parasites, and I Staging area viruses Fertilizers, herbicides, pesticides, fungicides shall be applied in the minimum amounts recommended by the manufacturer. Once applied, shall be worked into the soil to limit exposure to stormwater. De- icers, dust controllers, etc. shall also be applied in the minimum amounts recommended by the manufacturer. Storage materials shall be in a covered shed or trailer located outside of the 100' buffer zone and the contents of any partially used bags shall be transferred to a sealable plastic bag or bin to avoid spills. Williams & Sparages LLC 1 EROSION AND SEDIMENT CONTROL BMPS Minimize Disturbed Area and Protect Natural Features and Soil In general, the installation of the silt fencing (or approved equal) will demarcate the limit of work on the project. Once the silt fence is installed, the local Conservation Commission Agent will be asked to conduct a site visit to review and approve the limit of work in the field. The first phase of the project will involve the construction of the roadway and stormwater management areas. After the silt fence has been approved in the field, trees within the limit of work will be cleared. After the stumps have been removed, topsoil will be stripped and stockpiled on site. Best Management Practices for the silt fence installation and topsoil handling is detailed below. Existing Wetlands and Vegetation BMP Description: Silt fencing (or approved equal) will be installed to protect the existing wetlands and vegetation areas. Silt fencing will be installed by excavating a 12- inch -deep trench along the line of proposed installation. Wooden posts supporting the silt fence will be spaced 4 to 6 feet apart and driven securely into the ground; a minimum of 18 to 20 inches deep. The silt fence will be fastened securely to the wooden posts with wire ties spaced every 24 inches at the top, mid section, and bottom of the wooden post. The bottom edge of the silt fence will extend across the bottom of the trench and the trench will be backfilled and compacted to prevent stormwater and sediment from discharging underneath the silt fence. For design specifications, see Figure A. Installation Schedule: The silt fencing will be installed before construction begins at the site. Maintenance and Silt fencing will be inspected weekly and immediately after storm Inspection: events to ensure it is intact and that there are no gaps where the fence meets the ground or tears along the length of the fence. If gaps or tears are found during the inspection, the fabric will be repaired or replaced immediately. Accumulated sediment will be removed from the fence base if it reaches one -third the height of the silt fence and hauled off- site for disposal. If accumulated sediment is creating noticeable strain on the fabric and the fence might fail from a sudden storm event, the sediment will be removed more frequently. Before the fence is removed from the project area, accumulated sediment will be removed. The anticipated life span of the silt fence is 6 months and will likely need to be replaced after this period. Responsible Staff: I Site Contractor Topsoil BMP Description: Topsoil stripped from the immediate construction area will be stockpiled on site. Installation Schedule: I Topsoil will be stripped and removed during grading activities. Maintenance and I N/A Inspection: Responsible Staff: I Site Contractor Williams & Sparages LLC 2 Phase Construction Activity The following general construction sequence is anticipated for the project. 1) Pre - Construction meeting with representatives of the Conservation Commission and other Town officials as required. 2) Install siltfence (or approved equal) line as shown on the approved drawings. The erosion control line shall be inspected by a representative of the Conservation Commission prior to the commencement of clearing and earth- moving activities. 3) Establish additional limits of work with survey markers to delineate the limit of clearing. 4) Clear and grub the proposed project area. This work must be done prior to stripping and stockpiling the topsoil. 5) Strip and stockpile topsoil where shown on site plan. 6) Stormwater Management Areas (SWMAs) will be constructed next as shown on the approved plans. SWMAs will be loamed and vegetated as soon as possible in order to achieve stabilization. 7) Building construction will begin next. During this on going work, all disturbed areas away from building construction activities will be loamed and seeded to stabilize as much of the site as possible. Final landscaping as shown on approved plans should be completed at this time 8) Pave the two (2) additional parking lot areas. 9) Water, Drainage, Sewer, electric, and communications pipelines and structures will be installed next as shown on the approved plans. 10) Construct the proposed septic system and retaining walls. 11) Install finish pavement and then add striping as shown on the site plans. Control Stormwater Flowing onto and through the Project Once construction activities have commenced, sediment -lain stormwater runoff must be controlled on site. The silt fencing (or approved equal) has been designed to protect down - stream areas during construction activities. It is very important to perform more frequent inspections of the silt fencing during the initial earth moving phase to help prevent "blow- outs" of sediment beyond the silt fence limits. *See Erosion & Sediment Control Plan in the NOI Stabilize Soils Temaorary Stabilization BMP Description: Temporary vegetative cover should be established using hydro seeding for areas exposed soil (including stockpiles) where construction will cease for more than 14 days. Hydro seeding will consist of wood fibers, native seed, fertilizer, and stabilizing emulsion and applied at a rate of 8 pounds per acre. Seeding will be conducted during periods of the year when vegetation is more likely to be established. ❑ Permanent ® Temporary Installation Schedule: Temporary stabilization measures will be applied to portions of the site where construction activities will temporarily cease for more than 14 days. Maintenance and Stabilized areas will be inspected within six (6) weeks of planting and Inspection: after storm events until a dense cover of vegetation has become established. If failure is noticed at the seeded area, the area will be reseeded, fertilized, and mulched immediately. Water will be furnished as needed. Responsible Staff: Site Contractor Williams & Sparages LLC 3 Permanent Stabilization BMP Description: Permanent stabilization should begin immediately after the final design grades are achieved but no later than 14 days after construction ceases. Native species of plants will be used to establish vegetative cover on exposed soils. Permanent stabilization should be completed in accordance with the final stabilization procedures in Section 7. ® Permanent ❑ Temporary Installation Schedule: Portions of the site where construction activities have permanently ceased will be stabilized, as soon as possible but no later than 14 days after construction ceases. Maintenance and All seeded areas will be inspected weekly during construction activities Inspection: for failure and after storm events until a dense cover of vegetation has been established. If failure is noticed at the seeded area, the area will be reseeded, fertilized, and mulched immediately. After construction is completed at the site permanently stabilized areas will be monitored until final stabilization is reached. Responsible Staff: Site Contractor Mulching BMP Description: Hydromulching will provide immediate protection to exposed soils during short periods of construction. Hydromulch should be applied in areas that have been seeded for temporary or permanent stabilization. Straw mulch and wood fibers will be mixed with a tackifier (amount specified per manufacturer's instructions) and applied uniformly by machine with an application rate of 90 -100 pounds (2 -3 bales) per 1,000 square of 2 tons (100 -200 bales) per acre. If the tackifier does not appear effective in anchoring the mulch to the disturbed soil, crimping equipment will be used to provide additional binding to the soil. The mulch will cover 75 to 90 percent of the ground surface. Installation Hydromulch will be applied to exposed soils during short periods of construction Schedule: and seeded areas. Maintenance and Inspection: Mulched areas will be inspected weekly and after storm events to check for movement of mulch or erosion. If washout, breakage, or erosion occurs, the surface will be repaired, and new mulch will be applied to the damaged area. Responsible Staff: Site Contractor Dust Control BMP Description: Dust from the site will be controlled by using a mobile pressure -type distributor truck to apply potable water to disturbed areas. The mobile unit will apply water at a rate of 300 gallons per acre and minimized as necessary to prevent runoff and ponding. Installation Dust control will be implemented as needed once site grading has been initiated Schedule: and during windy conditions (forecasted or actual wind conditions of 20 mph or greater) while site grading is occurring. Spraying of potable water will be performed no more than three times a day during the months of May - September and once per day during the months October -April or whenever the dryness of the soil warrants it. Maintenance and Inspection: At least one mobile unit will be available at all times to distribute potable water to control dust on the project area. Each mobile unit will be equipped with a positive shutoff valve to prevent over watering of the disturbed area. For vehicle and equip ment maintenance practices, see Section 3, Part 3.4. Responsible Staff: Site Contractor Williams & Sparages LLC 4 Establish Perimeter Controls and Sediment Barriers Perimeter controls and sediment will be accomplished through the use of silt fencing (or approved equal). Silt fencing shall be installed and maintained as described in the Erosion and Sedimentation Control plan found in the NOI. Retain Sediment On -Site As previously discussed, once construction activities have commenced, sediment -lain stormwater runoff must be controlled on site. This will be accomplished through the use of the perimeter silt fencing. Additional BMPs Street Sweeping BMP Description: Street sweeping will be performed on the roadway within the subdivision and Dodge Road as needed or required by the Rowley Town Engineer. Installation Schedule: ( As needed or required by Rowley Town Engineer. Maintenance and All materials collected during street sweeping will be disposed of at an Inspection: off -site location by the subcontractor. Responsible Staff: I Site Contractor GOOD HOUSEKEEPING BMPS Material Handling and Waste Management Waste Materials BMP Description: All waste materials will be collected and disposed of into metal trash dumpsters in the combined staging area. Dumpsters shall be placed away from stormwater conveyances and drains, and meet all local and state solid -waste management regulations. Only trash and construction debris from the site will be deposited in the dumpsters. All personnel will be instructed, during tailgate training sessions, regarding the correct procedure for disposal of trash and construction debris. Installation Schedule: I Trash dumpsters will be brought to the site once the staging area has been established. Maintenance and The dumpsters will be inspected weekly and immediately after storm Inspection: events. The dumpster will be emptied when full. If trash and construction debris are exceeding the dumpsters capacity, the dumpsters will be emptied more frequently. Responsible Staff: I Individual Contractors Williams & Sparages LLC 5 Hazardous Waste BMP Description: All hazardous waste materials such as oil filters, petroleum products, paint, and equipment maintenance fluids will be stored in structurally sound and sealed shipping containers in the hazardous - materials storage area and segregated from other non -waste materials. Secondary containment will be provided for all materials in the hazardous materials storage area and will consist of commercially available spill pallets. Additionally, all hazardous materials will be disposed of in accordance with federal, state, and municipal regulations. Hazardous waste materials will not be disposed of into the on -site dumpsters. All personnel will be instructed, during tailgate training sessions, regarding the correct procedure for hazardous waste disposal. Installation Schedule: Shipping containers used to store hazardous waste materials will be installed once the materials storage area has been installed for the site and individual lots. Maintenance and Inspection: The hazardous materials storage areas will be inspected weekly and after storm events. The storage areas will be kept clean, well organized, and equipped with ample cleanup supplies as appropriate for the materials being stored. Material safety data sheets, material inventory, and emer ency contact numbers will be maintained by the contractor. Responsible Staff: Individual Contractors Sanitary Waste BMP Description: Temporary sanitary facilities (portable toilets) will be provided at the site in the staging area. The toilets will be placed away from a concentrated flow paths and traffic flow and will have collection pans underneath as secondary containment. Installation Schedule: The portable toilets will be brought to the site once the combined staging area has been established. Maintenance and Inspection: All sanitary waste will be collected from the portable toilets in accordance with local and state regulations. The toilets will be inspected weekly for evidence of leaking holding tanks. Toilets with leaking holding tanks will be removed from the site and replaced with new portable toilets. Responsible Staff: Local Portable Toilet Company/ Individual Contractors Establish Proper Building Material Staging Areas Combined Staging Area BMP Description: Construction equipment and maintenance materials will be stored at the staging area and materials storage areas. Nonhazardous building materials such as packaging material (wood, plastic, and glass), and construction scrap material (brick, wood, steel, metal scraps, and pipe cuttings) will be stored in a separate covered storage facility adjacent to the shipping container. All hazardous -waste materials such as oil filters, petroleum products, paint, and equipment maintenance fluids will be stored in structurally sound and sealed containers under cover within the hazardous materials storage area. Large items, such as framing materials and stockpiled lumber, will be stored in the open in the storage area. Such materials will be elevated on wood blocks to minimize contact with runoff. Williams & Sparages LLC 6 Installation Schedule The staging and materials storage area will be installed after grading and before any infrastructure is constructed at the site. The material storage areas for individual lots will be installed before construction begins for each house. Maintenance and Storage areas will be inspected weekly and after storm events. Storage Inspection: areas will be kept clean, well organized, and equipped with ample cleanup supplies as appropriate for the materials being stored. Perimeter controls, containment structures, covers, and liners will be repaired or replaced as needed to maintain proper function. Responsible Staff: I Site Contractor Establish Proper EquipmenWehicle Fueling and Maintenance Practices Vehicle /Equipment Fueling and Maintenance BMP Description: Several types of vehicles and equipment will be used on -site throughout the project, including but not limited to graders, excavators, loaders, paving equipment, rollers, trucks and trailers, backhoes, and forklifts. All major equipment/vehicle maintenance will be performed off -site. A small, 20- gallon pickup bed fuel tank will be kept on -site in the staging area. When vehicle fueling must occur on -site, the fueling activity will occur in the staging area. Only minor equipment maintenance will occur on -site. All equipment fluids generated from maintenance activities will be disposed of into designated drums stored on spill pallets in accordance with Section 3, Part 3.1. Absorbent, spill - cleanup materials and spill kits will be available at the staging and materials storage area. Drip pans will be placed under all equipment receiving maintenance. Installation Schedule: Equipment and vehicle maintenance and fueling practices will be implemented at the beginning of construction on -site. Maintenance and Inspect equipment/vehicle storage areas and fuel tank weekly and Inspection: after storm events. Vehicles and equipment will be inspected on each day of use. Leaks will be repaired immediately, or the problem vehicle(s) or equipment will be removed from the project site. Keep ample supply of spill - cleanup materials on -site and immediatelv clean up spills and dispose of materials Droperiv. Responsible Staff: I Individual Contractors Control EquipmentlVehicle Washing BMP Description: All equipment and vehicle washing will be performed off -site. Installation Schedule: I N/A Maintenance and I N/A Inspection: Responsible Staff: I Site Contractor Williams & Sparages LLC 7 Spill Prevention and Control Plan Spill Prevention and Control Procedures BMP Description: L Employee Training: All employees will be trained via biweekly tailgate sessions, as detailed in Section 6, Part 6.3. ii. Vehicle Maintenance: Vehicles and equipment will be maintained off -site. All vehicles and equipment including subcontractor vehicles will be checked for leaking oil and fluids. Vehicles leaking fluids will not be allowed on -site. Drip pans will be placed under all vehicles and equipment that are parked overnight. iii. Hazardous Material Storage: Hazardous materials will be sorted in accordance with Section 3, Part 1 and federal and municipal regulations. iv. Spill Kits: Spill kits will be within the materials storage area and concrete washout areas. v. Spills: All spills will be cleaned up immediately upon discovery. Spent absorbent materials and rags will be hauled off -site immediately after the spill is cleaned up for disposal. Spills large enough to discharge to surface water will be reported to the National Response Center at 1 -800- 424 -8802. vi. Material safety data sheets, a material inventory, and emergency contact information will be maintained at the on -site project trailer. Installation The spill prevention and control procedures will be implemented once Schedule: construction begins on -site. Maintenance and All personnel will be instructed, during tailgate training sessions, Inspection: regarding the correct procedures for spill prevention and control. The individual who manages day -to -day site operations will be responsible for seeing that these procedures are followed. Responsible Staff: I Site Contractor Williams & Sparages LLC 8 250 CLARK STREET (Flight Landata, Inc.) NORTH ANDOVER, MA INSPECTION AND MAINTENANCE REPORT FORM TO BE COMPLETED EVERY 7 DAYS AND WITHIN 24 HOURS OF A RAINFALL EVENT OF 0.5 INCHES OR GREATER Name of Inspector: Inspector's Company /Affiliation: Days Since Last Rainfall: Date: Amount of Last Rainfall: Maintenance Required: To Be Performed By: On of Before: 250 CLARK STREET (Flight Landata, Inc.) NORTH ANDOVER, MA INSPECTION AND MAINTENANCE REPORT FORM TO BE COMPLETED EVERY 7 DAYS AND WITHIN 24 HOURS OF A RAINFALL EVENT OF 0.5 INCHES OR GREATER Name of Inspector: Inspector's Company /Affiliation: Days Since Last Rainfall: Date: Amount of Last Rainfall: Maintenance Required: To Be Performed By: On of Before: #250 Clark Street North Andover, Massachusetts Erosion & Sediment Control Plan (February 7, 2013) Summary In order to limit the amount of erosion and sediment that takes place during and after construction, it is important to implement a management plan, which will protect and limit the amount of land area that is devoid of vegetation at any given time. Prior to Construction Prior to start of construction activities, the owner, builder, and site contractor should clearly identify all wetland resource areas that may be affected by the proposed clearing and earth moving activities by reviewing the approved grading plan as part of an initial site visit. During the site visit, the limit of work line should be reviewed to confirm the type of erosion control measure to be used to protect downstream wetland resources and abutting property. Limits of tree clearing should be verified during the initial site visit with emphasis on identifying "save areas' for existing trees and vegetation where practicable. Erosion and Sediment Control Device Siltfence is proposed as the primary erosion control device for this project (see attached construction detail for siltfence installation). It is important for the owner, builder, and /or site contractor to have access to a supply of haybales should the need arise for additional erosion and sediment control measures. Haybales can be used along a slope and /or together with siltfence to protect against concentrated stormwater runoff over exposed surfaces (see attached construction detail for haybale installation). The erosion and sediment control devices should be inspected every 7 days or within 24 -hours of a 1 -inch (or greater) rainfall event to ensure that they are operating properly. If sediment levels begin to build up on the erosion control devices, it may be necessary to remove the accumulated sediment to ensure that the erosion control devices continue to operate as designed. Sediment should be removed if it builds up more than 12- inches above the ground surface at the erosion control device. Earth - moving Activities After trees and other vegetation are cleared, earth - moving (or grading) activities can begin. The approved grading plan should be used to help guide the site contractor during regrading activities. Often times it is helpful to have a land surveyor establish benchmark elevations and/or lines of grade to aid the site contractor during regrading activities. This is the time during which the site is most vulnerable to erosion. Therefore, it is important for the site contractor to finalize grading activities as soon as practicable following land clearing. Areas than remain exposed longer than 30 working days in an interim condition should be stabilized in a temporary fashion. Once final grades have been established, permanent vegetation can be established. Erosion & Sediment Control Plan 250 Clark Street February 7, 2013 Temporary Seeding During construction it may be necessary to temporarily stabilize areas that will not be brought to final grade for a period longer than 30 working days. Temporary seeding is accomplished using fast - growing grass seed species such as ryegrass. Seeding should be performed in accordance with the guidelines set forth in Attachment A to this narrative, which is an excerpt from a publication entitled, "Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas, May 2003, prepared by Franklin, Hampden, and Hampshire Conservation Districts." Permanent Seeding & Plantings Once final grades have been established and the weather permits, every effort should be made to establish permanent vegetation on disturbed and exposed areas. In addition to grass seed, tree and shrub plantings should be an integral part of the permanent stabilization plan. Care should be taken by the owner, builder, and /or site contractor to select trees, shrubs, and seed mixes that are best suited to the soil conditions on the site. Soil moisture, depth to seasonal groundwater, and exposure to sunlight should be carefully considered when selecting species. In recent years, the emphasis on using plant species native to Massachusetts has grown. Information on the use of non -native and native species can be found on the web and in many local nursery catalogs. Permanent seeding should be performed in accordance with the guidelines set forth in Attachment B to this narrative, which is an excerpt from a publication entitled, "Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas, May 2003, prepared by Franklin, Hampden, and Hampshire Conservation Districts." Erosion and Sediment Control Practices The establishment of perennial vegetative cover on disturbed areas. Purpose WAyDWNW Permanent seeding of grass and planting trees and shrubs `-- ell provides stabilization to the soil by f. j holding soil particles in place. Vegetation reduces` _ sediments and runoff to STANUAi1CiMM14 downstream areas by slowing the velocity of runoff and permitting greater infiltration of the runoff. Vegetation also filters sediments, helps the soil absorb water, improves wildlife habitats, and enhances the aesthetics of a site. Where Practice Applies Permanent seeding and planting is appropriate for any graded or cleared area where long -lived plant cover is needed to stabilize the soil. Areas which will not be brought to final grade for a year or more. Some areas where permanent seeding is especially important are filter strips, buffer areas, vegetated swales, steep slopes, and stream banks. This practice is effective on areas where soils are unstable because of their texture or structure, high water table, winds, or steep slope. Advantages 957 Advantages of seeding over other means of establishing plants include the small initial establishment cost, the wide variety of grasses and legumes available, low labor requirement, and ease of establishment in difficult areas. Seeding is usually the most economical way to stabilize large areas. Well established grass and ground covers can give an aesthetically pleasing, finished look to a development. Once established, the vegetation will serve to prevent erosion and retard the velocity of runoff. Disadvantages/Problems Disadvantages which must be dealt with are the potential for erosion during the establishment stage, a need to reseed areas that fail to establish, limited periods during the year suitable for seeding, and a need for water and appropriate climatic conditions during germination. Vegetation and mulch cannot prevent soil slippage and erosion if soil is not inherently stable.