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HomeMy WebLinkAbout2021-03-16 Stormwater Peer Review & Response Comments Horsley: Wiife. 'Group I"tirt November 10, 2020 Ms. Jean Enright, Planning Director Planning Department Town of North Andover 120 Main Street, North Andover, Massachusetts 01845 Ref: Initial Stormwater Peer Review 419 & 435 Andover Street North Andover, Massachusetts Dear Ms. Enright and Board Members: The Horsley Witten Group, Inc. (HW) is pleased to provide the North Andover Planning Board with this letter report summarizing our initial review of the Stormwater Management Report and Site Plans for the proposed development at 419 &435 Andover Street, North Andover, MA. The plans were prepared for Crosspoint Associates (Applicant) by Bohler Engineering. The project proposes the redevelopment of a portion of the 2.68-acre parcel that currently consists of two existing buildings and two parking areas. HW understands that the Applicant is proposing to demolish one of the existing buildings ongite (totaling 24,088 sf) and replace it with two smaller buildings (totaling 10,852 so and additional parking. The site is not within an Area of Critical Concern or a Water Resource Protection District and is outside of the FEMA 1 00-year flood zone. The following documents and plans were received by HW., • Drainage Report for Crosspoint Associates for proposed "Commercial Development' at 419 & 435 Andover Street, North Andover, Massachusetts, prepared by Bohler Engineering, dated October 22, 2020; • Special Permit—Site Plan Review—Application, prepared by Crosspoint Associates, dated October 16, 2020; • Town of North Andover Planning Board —Application for Special Permit, prepared by Crosspoint Associates, dated October 16, 2020; • Traffic Impact Assessment for Crosspoint Associates for proposed "Commercial Development" at 419 &435 Andover Street, North Andover, Massachusetts, prepared by Vanasse &Associates Inc., dated October 2020; • Proposed Site Plan Documents, 419 & 435 Andover Street, North Andover, Massachusetts, prepared by Bohler Engineering, dated October 22, 2020, which include: o Cover Sheet C-101 o General Notes Sheet C-102 o Demolition Plan C-201 HorsleyWitten.com 91 gHorsleffliffenGroup Horsley Witten Group, Inc. Town of North Andover November 10, 2020 Page 2 of 5 o Site Layout Plan C-301 o Grading and Drainage Plan C-401 o Utility Plan C-501 o Erosion and Sediment Control Plan C-601 o Erosion and Sediment Control Plan Details C-602 o Landscape Plan L-100 o Landscape Notes and Details L-101 o Lighting Plan L-200 o Detail Sheet C-901 o Detail Sheet C-902 o Detail Sheet C-903 o Detail Sheet C-904 • Boundary and Topographic Survey (included in plan set), 419 & 435 Andover Street, North Andover, Massachusetts, prepared by Thompson's Inc, dated February 26, 2020. Stormwater Management Design Peer Review HW offers the following overall comments concerning the stormwater management design as per the Massachusetts Stormwater Handbook(MSH) dated February 2008, the North Andover Stormwater Management and Erosion Control Regulations (Stormwater Regulations) adopted February 15, 2011, and the North Andover Stormwater Management and Erosion Control Bylaw (Bylaw). The comments below correlate with the MSH standards and where the more stringent Town requirements are applicable additional comments are noted. The development may be considered a mix of new and redevelopment. The Applicant is increasing impervious surfaces and is managing the stormwater in compliance with the mare stringent requirements for new development. 1. Standard 9 states that no new stormwater conveyances (e.g. outfalls) may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. a. The existing site discharges stormwater to one design point(DP): o DP 1: The site generally flows from east to west and sheet flows offsite. b. Under proposed conditions the Applicant has provided stormwater practices to collect, manage, treat and recharge the stormwater within the developed areas of the site. The watershed areas and flow rates that discharge toward a single design point have been reduced under proposed conditions. At DP 1 the water overflows into a level spreader and into a separate perforated pipe infiltration trench. Any overflow from this system would then discharge to waters of the Commonwealth. The Applicant appears to comply with Standard 1. No further comment. 2. Standard 2 requires that stormwater management systems shall be designed so that post- development peak discharge rates do not exceed pre-development peak discharge rates. K:\Prqjeds\20JM18065N Andover On-Ca111 WOT 419 Andover SAReport12011 10 1st Peer Revi=419 Andover Street.docx Town of North Andover November 10, 2020 Page 3 of 5 a. The Applicant has proposed one large subsurface infiltration system for the site. In addition to the system, it appears that the Applicant is calling for surface level storage during larger storm events at specific locations onsite. Specifically, at C13-10 and WQI-1. These overflow areas are not mentioned in the narrative. The surface ponding calculated at WQI-1 does not appear consistent with the elevations on the plans as the surface level grate is at 208.8 and the HydroCAD model lists the elevation at 205.8. HW recommends that the Applicant revisit the plans verse the HydroCAD and confirm the values presented. The surface ponding may be referencing WQU-2. If there is surface level ponding upstream of the system, HW recommends evaluating all discharge points. It appears that an area drain (AD-4) is interconnected to the system and would likely overtop and overflow offsite first. HW recommends that the Applicant analyze the pipe sizing for the routing to the system onsite and evaluate the conveyance. b. The Applicant has indicated storage within the overflow control structure. During a large storm event in which the water is entering the structure and exiting at the same rate (where the water is not impeded by the orifice or weir because it is operating fully) it should not be filling as part of storage under a free discharge condition. c. The Applicant has designed the outlet control structure to flow to an infiltration trench that then bubbles out as necessary offsite. During a large storm event, the trench would fill up prior to overflowing. This would create a tailwater effect and not allow for a free discharge. HW recommends that the Applicant model the infiltration trench separately and evaluate.the effect of the discharge. 3. Standard 3 requires that the annual recharge from post-development shall approximate annual recharge from pre-development conditions. a. The Applicant has proposed a bottom invert for the Subsurface Detention System at elevation 199.5. The existing surface is at elevation 203. The Applicant has not conducted soil borings or test pits onsite to determine the estimated seasonal high groundwater(ESHGW)..HW recommends that the Applicant perform test pits to confirm that the proposed system will have at a minimum 2.0 feet of separation to groundwater as required for recharge. b. The Applicant has submitted recharge calculations and the stage storage model for its system to confirm that the post-development meets the annual recharge from pre- development conditions. The recharge calculation assumes that the ESHGW has sufficient separation from the bottom of the system. 4. Standard 4 requires that the storm water system be designed to remove 80% Total Suspended Solids (TSS) and to treat 0.5-inch of volume from the impervious area for wafer quality. a. The Applicant has provided a calculation of water quality volume (WQV) and TSS removal. The Applicant has proposed deep sump catch basins with hoods, 2 water quality inlets, 2 proprietary separators, and a subsurface infiltration basin to treat the water quality volume. KMrojectsV018118065 N Andover on-caial8065T 419 Andover St\Report1201110_I st Peer Review 419 Andover Street.doex Town of North Andover November 10, 2020 Page 4 of 5 b. The Applicant has proposed 2 water quality inlets and 2 proprietary separators. The sizing calculations for these units have not been included in the Drainage Report. HW recommends that the Applicant provide sizing calculations for these units to confirm the units specified have been sized correctly for the flow running through them. 5. Standard 5 is related to projects with a Land Use of Higher Potential Pollutant Loads (LUHPPL). a. The proposed development is not considered a LUHPPL therefore, Standard 5 is not applicable to this project. 6. Standard 6 is related to projects with storm water discharging into a critical area, a Zone II or an Interim Wellhead Protection Area of a public water supply. a. The proposed development is not within a critical area, Zone 11 or an IWPA area and therefore Standard 6 is not applicable. 7. Standard 7 is related to projects considered Redevelopment. a. The proposed development may be considered a mix of new and redevelopment. The Applicant has chosen to design the system as new development therefore Standard 7 is not applicable. 8. Standard 8 requires a plan to control construction related impacts including erosion, sedimentation, or other pollutant sources. a. The Applicant has provided an Erosion Control Plan. A Siltation Barrier is called for on the west side of the project, but there does not appear to be a detail included for this Barrier. HW suggests that the Applicant clarify if this is the compost filter sock referenced in the details or if this is a silt fence. b. The Applicant has not provided a SWPPP in the Site Plan Review materials. Per Bylaw 8.0, HW recommends that provision of a SWPPP be a condition of approval for the Site Plan Review permit. 9. Standard 9 requires a long-term operation and maintenance (O&M)plan shall be developed and implemented to ensure that stormwater management systems function as designed. a. The Applicant has provided an O&M Plan that appears to meet the standards established by MSH Vol. 2, Ch. 2 for maintenance of the proposed Subsurface Infiltration System. b. The Applicant has not included the signature of the property owner on the O&M Plan. Per Bylaw 9.1.a.ii, HW recommends that the Applicant provide a signed version of the O&M Plan. 10. Standard 10 requires that an Illicit Discharge Compliance Statement be provided. a. The Applicant has not provided an Illicit Discharge Compliance Statement in the Drainage Report signed by Crosspoint Associates. It is referenced in Appendix G. HW recommends that the Illicit Discharge Compliance Statement be signed by the property owner prior to land disturbance. K:\Projects12018i18065 N Andover On-Call\18065T 419 Andover St\Report1201110 1st Peer Review 419 Andover Street.doex I Town of North Andover November 10, 2020 Page 5of5 11. Closed Drainage Network and Swale sizing a. The Applicant has provided a storm drainage system including a system of piping between BMPs and the discharge point (DP). Per North Andover Storm Regulations (Section 7,2.13.g), the site shall be designed so that all the runoff from the site up to the 100-year storm enters the flow control structure(s). It appears that the design calls for some overland flow that goes offsite during larger events. HW recommends that the Applicant provide the pipe sizing calculations in the Drainage Report. Conclusions HW recommends that the Planning Board require that the Applicant address these comments as part of the Board's review process. The Applicant is advised that provision of these comments does not relieve him/her of the responsibility to comply with all Town of North Andover Codes and By-Laws, Commonwealth of Massachusetts laws, and federal regulations as applicable to this project. Please contact Janet Bernardo at 508-833-6600 or at jernardo@horsleywitten.com if you have any questions regarding these comments. Sincerely, HORSLEY WITTEN GROUP, INC. Janet Carter Bernardo, P.E. Steve Stanish, P.E Senior Project Manager Project Engineer K:Trojectsl2018118065 N Andover On-Ca11198065T 419 Andover StlReport1201 110 1st Peer Review 419 Andover Street.dom Hors 11Vit�en GrQlu'p 14jok Sustainable,Eavlrvnmental:$00tlons MtiN�tr'Streef etdo� e¢sloa MA.oziaa ��7-28381$3.s':tiorsleyrw3ileti.�om December 17, 2020 Ms. Jean Enright, Planning Director Planning Department Town of North Andover 120 Main Street North Andover, Massachusetts 01845 Ref: Second Stormwater Peer Review 419 & 435 Andover Street North Andover, Massachusetts Dear Ms. Enright and Board Members: The Horsley Witten Group, Inc. (HW) is pleased to provide the North Andover Planning Board with this letter report summarizing our second review of the Stormwater Management Report and Site Plans for the proposed development at 419 &435 Andover Street, North Andover, MA. The plans were prepared for Crosspoint Associates (Applicant) by Bohler Engineering. The project proposes the redevelopment of a portion of the 2.68-acre parcel that currently consists of two existing buildings and two parking areas. HW understands that the Applicant is proposing to demolish one of the existing buildings onsite (totaling 24,088 so and replace it with two smaller buildings (totaling 10,852 so and additional parking. The site is not within an Area of Critical Concern or a Water Resource Protection District and is outside of the FEMA 100-year flood zone. The following additional documents and plans were received electronically by HW in response to our initial peer review dated November 10, 2020: • Letter to the North Andover Planning Department, regarding Response to Comments, prepared by Bohler Engineering, dated December 8, 2020 (6 pages) • Proposed HydroCAD Modeling Report, printed November 19, 2020 (21 pages); • Rational Pipe Sizing Calculations, prepared by Bohler Engineering, dated November 19, 2020 (1 page); • Water Quality Sizing and TSS Removal Calculations, prepared by Contech (5 pages); and • Geotechnical Report, prepared by Geotechnical Consultants, Inc., revised December 8, 2020 (25 pages) • Proposed Site Plan Documents for Crosspoint, 419 & 435 Andover Street, North Andover, Massachusetts, prepared by Bohler Engineering, dated October 22, 2020, revised December 8, 2020, which include: o Cover Sheet C-101 o General Notes Sheet C-102 a Demolition'Plan C-201 HorsleyWitten.com @HorsleyWittenGroup ®Horsley Witten Group, Inc. Town of North Andover December 17, 2020 Page 2 of 6 o Site Layout Plan C-301 o Grading and Drainage Plan C-401 a Utility Plan C-501 o Soil Erosion & Sediment Control Plan C-601 o Erosion and Sediment Control Notes and Details C-602 o Detail Sheet C-901 o Detail Sheet C-902 o Detail Sheet C-903 o Detail Sheet C-904 o Detail Sheet C-905 o Boundary & Topographic Survey (Control Point Associates, Inc., 10-22-20) Stormwater Management Design Peer Review HW offers the following overall comments concerning the Stormwater management design as per the Massachusetts Stormwater Handbook(MSH) dated February 2008, the North Andover Stormwater Management and Erosion Control Regulations (Stormwater Regulations) adopted February 15, 2011, and the North Andover Stormwater Management and Erosion Control Bylaw (Bylaw). The comments below correlate with our initial peer review dated November 10, 2020. Follow up comments are provided in bold font. 1. Standard 1 states that no new stormwater conveyances (e.g. outfalls) may discharge untreated stormwaterdirectly to or cause erosion in wetlands or waters of the Commonwealth. a. The existing site discharges stormwater to one design point (DP): o DP 1: The site generally flows from east to west and sheet flows offsite. b. Under proposed conditions the Applicant has provided stormwater practices to . collect, manage, treat and recharge the Stormwater within the developed areas of the site. The watershed areas and flow rates that discharge toward a single design point have been reduced under proposed conditions. At DP 1 the water overflows into a level spreader and into a separate perforated pipe infiltration trench. Any overflow from this system would then discharge to waters of the Commonwealth. The Applicant appears to comply with Standard 1. No further comment. HW (12117120): No further comment. 2. Standard 2 requires that Stormwater management systems shall be designed so that post- development peak discharge rates do not exceed pre-development peak discharge rates. a. The Applicant has proposed one large subsurface infiltration system for the site. In addition to the system, it appears that the Applicant is calling for surface level storage during larger storm events at specific locations onsite. Specifically, at CB-10 and WQI-1. These overflow areas are not mentioned in the narrative. The surface ponding calculated at WQI-1 does not appear consistent with the elevations on the plans as the surface level grate is at 208.8 and the HydroCAD model lists the K:IProjectsM18118065 N Andover On-Call\18065T 419 Andover St\keport1201217 2nd Peer Review A 19 Andover Street.doex Town of North Andover December 17, 2020 Page 3 of 6 elevation at 205.8. HW recommends that the Applicant revisit the plans verse the HydroCAD and confirm the values presented. The surface ponding may be referencing WQU-2. If there is surface level ponding upstream of the system, HW recommends evaluating all discharge points. It appears that an area drain (AD-4) is interconnected to the system and would likely overtop and overflow offsite first. HW recommends that the Applicant analyze the pipe sizing for the routing to the system onsite and evaluate the conveyance. HW(12117120): The Applicant has revised its proposed HydroCAD and renamed A04 to CB-11 on the plans (Sheet C-401). The outfalls appear to still pond in areas of WQU-2, CB-10, and CB-11 as noted in the Applicant's response.A designed overflow has been added at CB-11 with riprap. HW recommends that the Applicant add spot grades behind the curb at WQU-2 to ensure ponding will not occur behind the curb in this area. b. The Applicant has indicated storage within the overflow control structure. During a large storm event in which the water is entering the structure and exiting at the same rate (where the water is not impeded by the orifice or weir because it is operating fully) it should not be filling as part of storage under a free discharge condition. HW (12117120): The Applicant has clarified the condition of the overflow structure as It relates to the routing in the revised HydroCAD. The explanation is reasonable. HW has no further comment. c. The Applicant has designed the outlet control structure to flow to an infiltration trench that then bubbles out as necessary offsite. During a large storm event, the trench would fill up prior to overflowing. This would create a tailwater effect and not allow for a free discharge. HW recommends that the Applicant model the infiltration trench separately and evaluate the effect of the discharge. HW (12117120): The Applicant has provided supporting information Including the dynamic routing of the HydroCAD model and separate trench information. The Applicant has also provided an updated Peak Storm Table with the revised values. HW has no further comment. The Applicant appears to comply with Standard 2. No further comment. 3. Standard 3 requires that the annual recharge from post-development shall approximate annual recharge from pre-development conditions. a. The Applicant has proposed a bottom invert for the Subsurface Detention System at elevation 199.5. The existing surface is at elevation 203. The Applicant has not conducted soil borings or test pits onsite to determine the estimated seasonal high groundwater(ESHGW). HW recommends that the Applicant perform test pits to confirm that the proposed system will have at a minimum 2.0 feet of separation to groundwater as required for recharge. HW (12117/20). The Applicant has provided a Geotechnical Report with soil borings at the location of the infiltration chamber. HW recommends that the Planning Board include as a condition of approval requiring that an additional K:\31rojects\2018\18065 N Andover On-Cal1118065T 419 Andover MReport1201217_2nd Peer Review 419 Andover Street.doex Town of North Andover December 17, 2020 Page 4 of 6 test pit be conducted within the footprint of the infiltration system at the start of construction. b. The Applicant has submitted recharge calculations and the stage storage model for its system to confirm that the post-development meets the annual recharge from pre- development conditions. The recharge calculation assumes that the ESHGW has sufficient separation from the bottom of the system. HW (12117120): The Applicant has provided supporting information including a Geotechnical Report with soil borings at the location of the infiltration chamber.The information from the boring and the proposed grading of this area should provide enough separation from the bottom of the system and the seasonal high groundwater table. HW recommends that the Planning Board include as a condition of approval requiring that an additional test pit will be conducted within the footprint of the infiltration system at the start of construction and provided to the Town. 4. Standard 4 requires that the stormwater system be designed to remove 80% Total Suspended Solids (TSS) and to treat 0.5-inch of volume from the impervious area for water quality. a. The Applicant has provided a calculation of water quality volume (WQV) and TSS removal. The Applicant has proposed deep sump catch basins with hoods, 2 water quality inlets, 2 proprietary separators, and a subsurface infiltration basin to treat the water quality volume. HW (12/17/20): No further comment. b. The Applicant has proposed 2 water quality inlets and 2 proprietary separators. The sizing calculations for these units have not been included in the Drainage Report. HW recommends that the Applicant provide sizing calculations for these units to confirm the units specified have been sized correctly for the flaw running through them. HW(12/17/20): The Applicant has provided sizing calculations and TSS removal calculations for the 2 proposed water quality inlets and 2 proprietary separators. The calculations have been included in the report and meet the 80%TSS removal rate. No further comment. 5. Standard 5 is related to projects with a Land Use of Higher Potential Pollutant Loads (L UHPPL). a. The proposed development is not considered a LUHPPL therefore, Standard 5 is not applicable to this project. HW (12117120): No further comment. 6. Standard 6 is related to projects with stormwater discharging into a critical area, a Zone 11 or an Interim Wellhead Protection Area of a public water supply, a. The proposed development is not within a critical area, Zone II or an IWPA area and therefore Standard 6 is not applicable. HW (12117120): No further comment. K:\PrqjectOO18\18065N Andover©n-CMM 8065T 4 t 9 Andover St\Reporfl2012!7_2nd Peer Review 419 Andover Street.doox Town of North Andover December 17, 2020 Page 5 of 6 7. Standard 7 is related to projects considered Redevelopment. a. The proposed development may be considered a mix of new and redevelopment. The Applicant has chosen to design the system as new development therefore Standard 7 is not applicable. HW (12117120): No further comment. 8. Standard 8 requires a plan to control construction related impacts including erosion, sedimentation, or other pollutant sources. a. The Applicant has provided an Erosion Control Plan. A Siltation Barrier is called for on the west side of the project, but there does not appear to be a detail included for this Barrier. HW suggests that the Applicant clarify if this is the compost filter sock referenced in the details or if this is a silt fence. HW (12117120): The Applicant has clarified the siltation barrier on the plans and provided the applicable details. No further comment. b. The Applicant has not provided a SWPPP in the Site Plan Review materials. Per Bylaw 8.0, HW recommends that provision of a SWPPP be a condition of approval for the Site Plan Review permit. HW (12117120): The Applicant has stated that a SWPPP will be prepared and provided for review prior to any land disturbance on site. HW recommends that the Planning Board consider requiring that receipt of the SWPPP be a condition of approval. 9. Standard 9 requires a long-term operation and maintenance (O&M) plan shall be developed and implemented to ensure that stormwater management systems function as designed. a. The Applicant has provided an O&M Plan that appears to meet the standards established by MSH Vol. 2, Ch. 2 for maintenance of the proposed Subsurface Infiltration System. HW (12/17/20) No further comment. b. The Applicant has not included the signature of the property owner on the O&M Plan. Per Bylaw 9.1.a.ii, HW recommends that the Applicant provide a signed version of the O&M Plan. HW (12/17/20)The Applicant has stated that it does not own this property at this time and has stated that a signed O&M Plan will be provided prior to any land disturbance on-site. HW recommends that the Planning Board consider requiring this as a condition of approval. 10. Standard 10 requires that an Illicit Discharge Compliance Statement be provided, a. The Applicant has not provided an Illicit Discharge Compliance Statement in the Drainage Report signed by Crosspoint Associates. It is referenced in Appendix G, HW recommends that the Illicit Discharge Compliance Statement be signed by the property owner prior to land disturbance. HW (12117120): The Applicant has stated that it does not own this property at this time and has stated that a signed Illicit Discharge Statement will be K:\Prqjec1s\2G18\19065 N Andover Qti-Ca11118065T 419 Andover St\Report1201217_2nd Peer Review 419,Andover Street.dom Town of North Andover December 17, 2020 Page 6 of 6 provided prior to any land disturbance on-site and as a condition of approval. HW recommends that the Planning Board consider requiring this as a condition of approval and has no further comment 11. Closed Drainage Network and Swale sizing a. The Applicant has provided a storm drainage system including a system of piping between BMPs and the discharge point(DP). Per North Andover Storm Regulations (Section 7.2.B.g), the site shall be designed so that all the runoff from the site up to the 100-year storm enters the flow control structure(s). It appears that the design calls for some overland flow that goes offsite during larger events. HW recommends that the Applicant provide the pipe sizing calculations in the Drainage Report. HW (12/17120) The Applicant has provided a rational pipe sizing calculation table. It appears to be incomplete. The table provides calculations for the main line and water quality or proprietary structures only. HW recommends that the Applicant include the following in the table: • All routing of pipes from all catch basins/inlets to the stormwater system. • . Inverts of pipe to confirm slope (also to confirm slope of pipe on plans) • Lengths of pipe to confirm slope (also to confirm slope of pipe on plans) Conclusions HW recommends that the Planning Board require that the Applicant address the few minor outstanding comments as part of the Board's review process. The Applicant is advised that provision of these comments does not relieve him/her of the responsibility to comply with all Town of North Andover Codes and By-Laws, Commonwealth of Massachusetts laws, and federal regulations as applicable to this project. Please contact Janet Bernardo at 508-833-6600 or at jbernardo@horsleywitten.com if you have any questions regarding these comments. Sincerely, HORSLEY WITTEN GROUP, INC. Janet Carter Bernardo, P.E. Steve Stanish,.P.E Senior Project Manager Project Engineer K:1ProjectA2018118065 N Andover On-Ca11118065'r 419 Andover 8tlRepor6201217_2nd Peer Review 419 Andover Street.docx I I ustainoblo-Environmental oo.•.7utio, %263�1�3:t<hbrseWltieri.�orri December 22, 2020 Ms. Jean Enright, Planning Director Planning Department Town of North Andover 120 Main Street North Andover, Massachusetts 01846 Ref: Third Stormwater Peer Review 419 &435 Andover Street North Andover, Massachusetts Dear Ms. Enright and Board Members: ' The Horsley Witten Group, Inc. (HW) is pleased to provide the North Andover Planning Board with this lefter.report summarizing.our third review of the Stormwater Management Report and Site Plans fdr.the proposed,deve,lopment at 419 &435 Andover Street, North Andover, MA The plans were prepared far drosspoint Associates (Applicant) by Bohler Engineering. The project proposes the redevelopment of a portion of the 2.68-acre parcel that currently consists of two existing buildings arid two parking areas. HW understands that the Applicant is proposing to demolish one of the existing buildings onsite (totaling 24,088 so and replace it with two smaller buildings (totaling 10,852 sf) and additional parking. The site is not within an Area of Critical Concern or a Water Resource,Protection District and is outside of the FEMA 100-year flood zone. The following additional documents and plans were received electronically by HW in response to our second peer review dated December 17, 2020: • Letter to the North Andover Planning Department, regarding Response to Comments, prepared by Bohler Engineering, dated December 21, 2020 (2 pages) • Rational Pipe Sizing Calculations, prepared by Bohler Engineering, dated December 21, 2020 (1 page); • Proposed Site Plan Documents for Crosspoint, 419 &435 Andover Street, North Andover, Massachusetts, prepared by Bohler Engineering, dated October 22, 2020, revised December 21, 2020, which.include: a Cover Sheet C-101 o General Notes Sheet C-102 o Demolition Plan C-201 a Site Layout Plan C-301 o Grading and Drainage Plan C-401 o Utility Plan C-501 o Soil Erosion &Sediment Control Plan C-601 �+ <.s HorsleyWiften.com @HorsleyWiffenGroup WJHors]ey Wifie'n Group, Inc. 'H y-Wiften "G .-' ' Ousfa ablo-EnvironmentalO47utions ' 3�z �tatS[r�s,�'•;a�;:�[q��','+:s��"to4���1Ab��.�a: . .1 Vt 8t37�283�813:!hors[eyyiltteri.com December 22, 2020 Ms. Jean Enright, Planning Director Planning Department Town of North Andover 120 Main Street North Andover, Massachusetts 01845 Ref: Third Stormwater Peer Review 419 &435 Andover Street North Andover, Massachusetts Dear Ms. Enright and Board Members; The Horsley Witten Group, Inc, (HW) is pleased to provide the North Andover Planning Board with this letter report summarizing our third review of the Stormwater Management Report and Site Plans for the proposed development at 419 & 435 Andover Street, North Andover, MA. The plans were prepared for Crosspoint Associates (Applicant) by Bohler Engineering. The project proposes the redevelopment of a portion of the 2.68-acre parcel thdt currently con'sists of two existing buildings and two parking areas. HW understands that the Applicant is proposing to demolish one of the existing buildings onsite (totaling 24,088 sf) and replace it with two smaller buildings (totaling10,852 so and additional parking. The site is not within an Area of Critical Concern or a Water Resource,Protection District and is outside of the FEMA 100-year flood zone. The following additional documents and plans were received electronically by HW in response to our second peer review dated December 17, 2020: Letter to the North Andover Planning Department, regarding Response to Comments, prepared by Bohler Engineering, dated December 21, 2020 (2 pages) • Rational Pipe Sizing Calculations, prepared by Bohler Engineering, dated December 21, 2020 (1 page); + Proposed Site Plan Documents for Crosspoint, 419 &435 Andover Street, North Andover, Massachusetts, prepared by Bohler Engineering, dated October 22, 2020, revised December 21, 2020, which include: ` o Cover Sheet C-101 o General Notes Sheet C-102 o Demolition Plan C-201 o Site Layout Plan C-301 o Grading and Drainage Plan C-401 o Utility Plan C-501 o Soil Erosion &Sediment Control Plan C-601 �f HorsleyWittan.com @a HorsleyWittenGroup W.IlHorsley Wi%n Group, Inc. Town of North Andover December 22, 2020 Page 3 of 4 WQU-2, CB-10, and CB-1I as noted in the Applicant's response. A designed overflow has been added at CB-1 9 with riprap. HW recommends that the Applicant add spot grades behind the curb at WQU-2 to ensure ponding will not occur behind the curb in this area. HW (12122120): The Applicant has provided additional spot grades on Sheet C- 401 as requested, No further comment. The Applicant complies with Standard 2. 3. Standard 3 requires that the annual recharge from post-development shall approximate annual recharge from pre-development conditions. HW (12122120): HW recommends that the Planning Board include as a condition of approval requiring that an additional test pit be conducted within the footprint of the infiltration system at the start of construction. The Applicant complies with Standard 3. 4. Standard 4 requires that the stormwater system be designed to remove 80% Total Suspended Solids (TSS) and to treat 0.5-inch of volume from the impervious area for water quality. HW (12122120): The Applicant complies with Standard 4. 5. Standard 5 is related to projects with a Land Use of Higher Potential Pollutant Loads (LUHPPL). a. The proposed development is not considered a LUHPPL therefore, Standard 5 is not applicable to this project. HW (12117120): No further comment. 6. Standard 6 is related to projects with stormwater discharging into a critical area, a Zone/1 or an Interim Wellhead Protection Area of a public water supply. a. The proposed development is not within a critical area, Zone 11 or an IWPA area and therefore Standard 6 is not applicable. HW (12117120): No further comment. 7. Standard 7 is related to projects considered Redevelopment. a. The proposed development may be considered a mix of new and redevelopment. The Applicant has chosen to design the system as new development therefore Standard 7 is not applicable. HW (12117120): No further comment. 8, Standard 8 requires a plan to control construction related impacts including erosion, sedimentation, or other pollutant sources. HW (12122120): HW recommends that the Planning Board consider requiring that receipt of the SWPPP be a condition of approval. KVrojec4A1201 TJ 8065 N Andover On-COM065T 419 Andover S(\RoportM 1222_3rd Peer Review 419 Andover Street.docx Town of North Andover December 22, 2020 Page 4 of 4 9. Standard 9 requires a longterm operation and maintenance (OW)plan shall be developed and implemented to ensure that stormwatermanagement systems function as designed. HW (12122120): HW recommends that the Planning Board consider requiring receipt of a signed O&M Plan as a condition of approval. 10. Standard 10 requires that an Illicit Discharge Compliance Statement be provided. HW (12/122/20): HW recommends that the Planning Board consider requiring receipt of a signed Illicit Discharge Statement as a condition of approval. 11. Closed Drainage Network and Swale sizing a. The Applicant has provided a storm drainage system including a system of piping between BMPs and the discharge point (DP). Per North Andover Storm Regulations (Section 7.2.B.g), the site shall be designed so that all the runoff from the site up to the 100-year storm enters the flow control structure(s). It appears that the design calls for some overland flow that goes offslte during larger events. HW recommends that the Applicant provide the pipe sizing calculations in the Drainage Report. HW(12117120) The Applicant has provided a rational pipe sizing calculation table. It appears to be incomplete. The table provides calculations for the main line and water quality or proprietary structures only. HW recommends that the Applicant include the following in the table: • All routing of pipes from all catch basins/inlets to the stormwater system. • Inverts of pipe to confirm slope (also to confirm slope of pipe on plans) • Lengths of pipe to confirm slope (also to confirm slope of pipe on plans) HW (12122120): The Applicant has provided the requested rational pipe sizing calculation table. No further comment. Conclusions HW is satisfied that the Applicant has addressed our comments. The Applicant is advised that provision of these comments does not relieve him/her of the responsibility to comply with all Town of North Andover Codes and By-Laws, Commonwealth of Massachusetts laws, and federal regulations as applicable to this project. Please contact Janet Bernardo at 508-833-6600 or at jbernardo@horsleywitten.com if you have any questions regarding these comments. Sincerely, HORSL.EY WITTEN GROUP, INC. Janet Carter Bernardo, P.E. Senior Project Manager K:\Projects12018118065 N Andover 0n-Calhl 8065T 419 Andover 5t\Report1201222_3rd Peer Review 419 Andover 5treet.doex 45 Franklin Street, 5th Floor BO Boston, MA 02110 H ,LE.R // 617.849.8040 December 8, 2020 North Andover Planning Department 120 Main Street North Andover, MA 01845 Attn: Jean Enright, Planning Director Oen rig ht@northandoverma.gov) Re: Response to Comments for Stormwater Peer Review Letter 419 &435 Andover Street North Andover, MA Dear Ms. Enright, On behalf of the applicant, Crosspoint Associates, Inc., below please find our responses to the Initial Stormwater Peer Review Letter from Horsley Witten Group dated 11/10120, Included in support of these responses are the following materials: • One (1) copy of the Site Development Plans, prepared by Bohler, dated October 22, 2020, revised December 8, 2020; • One (1) copy of the Proposed HydroCAD Report, prepared by Bohler, dated October 22, 2020, revised December 7, 2020; One(1) copy of the Pipe Sizing Calculations, prepared by Bohler, dated November 17, 2020; • One(1) copy of the Water Quality Sizing and TSS Removal Calculations, prepared by Contech; and One(1)copy of the Geotechnical Report, prepared by Geotechnical Consultants, Inc., revised December 8, 2020. For clarity, the original comments are in a bold font type with numbering consistent with the review letter, while Bohler's responses are directly below in an italicized font type. Responses are provided only for comments that warrant a response. Comments: 2. a. The Applicant has proposed one large subsurface infiltration system for the site. In addition to the system, it appears that the Applicant is calling for surface level storage during larger storm events at specific locations onsite. Specifically, at CB-10 and WQI-1. These overflow areas are not mentioned in the narrative.The surface ponding calculated at WQI-1 does not appear consistent with the elevations on the plans as the surface level grate Is at 208,8 and the HydroCAD model lists the elevation at 205.8. HW recommends that the Applicant revisit the plans verse the HydroCAD and confirm the values presented. The surface ponding may be referencing WQU-2. If there is surface level ponding upstream of the system, HW recommends evaluating all discharge points. It appears that an area drain (AD-4) Is interconnected to the system and would likely overtop and overflow offsite first. HW recommends that the Applicant analyze the pipe sizing for the routing to the system onsite and evaluate the conveyance. www.BohlerFng€neer€ng.com B.,OHL,ER # Response to Comment: The HydroCAD model has been revised to clarify that, during extreme storm events, surface ponding will occur at WQU-2 and 08-10, as shown on the plans and in the HydroCAD report. The HydroCAD model and the Grading and Drainage Plan have also been revised to provide a formal overflow spillway to the discharge point, adjacent to CB-11, to ensure that stormwater is conveyed through the proposed stormwater system and through this flow control structure before flowing offsite. CB-11 (formerly AD-4) has also been upgraded from an area drain to a dry well structure to provide additional infiltration and serve as an outlet from the system in larger, less frequent storm events.All discharge points have been re-evaluated following these changes made to the HydroCAD model. Pipe sizing calculations have also been included for evaluation of routing to the system and conveyance on-site. 2. b. The Applicant has indicated storage within the overflow control structure. During a large storm event in which the water is entering the structure and exiting at the same rate(where the water is not impeded by the orifice or weir because it is operating fully) it should not be filling as part of storage under a free discharge condition. Response to Comment: The storage volume modeled for the outlet control structure (OCS-1)is negligible. This condition was produced in the report as it was necessary to connect the applicable substantial volumes at various elevations. 2. c. The Applicant has designed the outlet control structure to flow to an infiltration trench that then bubbles out as necessary offsite. During a large storm event,the trench would fill up prior to overflowing.This would create a tailwater effect and not allow for a free discharge. HW recommends that the Applicant model the infiltration trench separately and evaluate the effect of the discharge. Response to Comment: The infiltration trench level spreader has been modeled separately in HydroCAD to evaluate the effect of the discharge at this outlet area. The dynamic routing method was utilized in the revised model to account for the tailwater condition this outlet will create when receiving flow from the system. We have included the revised peak rate values below in Table 1 for reference to display that all peak rates continue to be reduced for the design storms. The revised HydroCAD model is also attached for reference. Table 1.1: Design Point Peak Runoff Rate Summary(Revision 11 Pont of Year$tarm 10 Year Storm 25 Year Sfarm F{�0 Year Storm Analysis Pre Post a Pre Post Q Pre Past a Pre Past e DP1 7.35 5.02 -2.37 11.77 11.71 .0.06 15.01 14.56 .0.46 21.98 21.49 -0.49 3. a. The Applicant has proposed a bottom invert for the Subsurface Detention System at elevation 199.6.The existing surface is at elevation 203.The Applicant has not conducted soil borings or test pits onsite to determine the estimated seasonal high groundwater(ESHGW). HW recommends that the Applicant perform test pits to www.BohlerEngineeOng.corn i BOHLER // confirm that the proposed system will have at a minimum 2.0 feet of separation to groundwater as required for recharge. 3. b. The Applicant has submitted recharge calculations and the stage storage model for its system to confirm that the post-development meets the annual recharge from pre- development conditions. The recharge calculation assumes that the ESHGW has sufficient separation from the bottom of the system. Response to Comment: A preliminary geotechnical investigation has since been performed by the Applicant and the report has been included with this response letter. Based on soil borings, groundwater appears to range from 10 to 15 feet below existing ground surface (B-6 and B-7), or even deeper(B-1 and B-2). Boring B-3 was located near the existing roof drains and a failed drywell with standing water observed onsite, and therefore was determined not to be representative of existing groundwater conditions. Given the depth to groundwater observed in the other locations, and the shallow depth required to for 2 feet separation from groundwater(5.5 feet below existing grade) it appears that this condition should be met. The current HydroCAD model has also taken a conservative approach by not modeling for infiltration. The required separation can be confirmed again at the start of construction by a test pit and verified with the Town as a condition of approval. 4. b. The Applicant has proposed 2 water quality inlets and 2 proprietary separators.The sizing calculations for these units have not been included in the Drainage Report. HW recommends that the Applicant provide sizing calculations for these units to confirm the units specified have been sized correctly for the flow running through them. Response to Comment.- Sizing calculations for the proprietary separators and water quality inlets were received from Contech on Friday, November 61h. These calculations have been included to confirm sufficient sizing has been provided from these structures. 8. a. The Applicant has provided an Erosion Control Plan.A Siltation Barrier is called for on the west side of the project, but there does not appear to be a detail included for this Barrier. HW suggests that the Applicant clarify if this is the compost filter sock referenced in the details or if this Is a silt fence. Response to Comment: The siltation barriers and details have been clarified on the revised Erosion Control Plan. 8. b. The Applicant has not provided a SWPPP in the Site Plan Review materials. Per Bylaw 8.0, HW recommends that provision of a SWPPP be a condition of approval for the Site Plan Review permit. Response to Comment. The SWPPP for this site will be prepared and provided for review in advance of construction and prior to any land disturbance on-site. The Applicant agrees that this can be a condition of approval for the permit. www.BohlerEngineering.com BOHLER // 9. b. The Applicant has not included the signature of the property owner on the O&M Plan. Per Bylaw 9.1.a.11, HW recommends that the Applicant provide a signed version of the O&M Plan. Response to Comment,- The Applicant does not currently own the property therefore, this signature will be provided to the Planning Board when tho property is under control of the Applicant. This signature from the property owner will be provided on the O&M Plan prior to any land disturbance on-site and can be a condition of approval. 10, a. The Applicant has not provided an Illicit Discharge Compliance Statement in the Drainage Report signed by Crosspoint Associates. It is referenced in Appendix G. HW recommends that the Illicit Discharge Compliance Statement be signed by the property owner prior to land disturbance. Response to Comment: The Applicant does not currently own the property,therefore, this signature will be provided to the Planning Board when the property is under control of the Applicant. This signature from the property owner will be provided for the Illicit Discharge Statement prior to any land disturbance on-site and can be a condition of approval. 11. The Applicant has provided a storm drainage system including a system of piping between BMPs and the discharge point(DP). Per North Andover Storm Regulations (Section 7.2,8.g), the site shall be designed so that all the runoff from the site up to the 100-year storm enters the flow control structure(s). It appears that the design calls for some overland flow that goes offsite during larger events. HW recommends that the Applicant provide the pipe sizing calculations in the Drainage Report. Response to Comment: Pipe sizing calculations for the project have been prepared and provided for the project based on the 10- year design storm, which is a generally accepted storm size. The HydroCAD model and the Grading and Drainage Plan have also been revised to provide a formal overflow spillway to the discharge point, adjacent to CB-11, to ensure that stormwater is conveyed through this flow control structure, up to including the 100-yearstorm event, before flowing offslte. As indicated in the HydroCAD model, it is understood that some surface pending will occur during these extreme and very infrequent storm events, however this design has been revised to route stormwater through a flow control structure(the spillway) to the discharge point during those extreme events. www.BohlerEngineefing.com BOHLER // We trust the above is sufficient for your needs at this time. Should you have any questions or require additional information, please do not hesitate to contact us at(617) 849-8040. Sincerely, BOHLER ENGINEERING Zachary L. Richards, P.E. Stephen Martorano, P.E. www.8ohlerEngineering,com M201047 Hydra PR-R[jV1 Prepared 6y{enleryour company name here} Printed 11110)2020 H d,.cADO 10 00-19 s,o 0gss as 20?6 H dioCAO Sofnaara 8e1.0ons LLc s Area Llsting(all nodes) Area CN Docrip60A (s AI (sv6calcsmant-nw60rs) 19,634 74 >76&assc ar,Gaod,HSG C(PROt) 78,661 88 Paved paddng,HSG C(PR01} 18,157 98 Roofs,HSGC(PROt) 416,672 94 TOTAL AREA Chambe System DPI Infiltration Trench O ec � l.ipk nowmgoi:greartorrrzBtwrHydryaaaEvt Prepared by{en;eryoVr CarparP/Iwnafiere},PMEed F7n9rzo10 rrraronnna snare.�eaau ot4w lyaxwsw.ere sao-�nun 1 , M201047 Hydro—PR•REVi M201047 Hydro PR•REVi Preperedby{enleryaurcompanyn mole ss) Ptiinled MIM020 Prepared by{entery0urcampany name here) Printed 1 1 71 01202 0 Hyd1oCAG®f00D-14 s1n 08956 d72016 HvdroGAn Saflware 5oldians LLC _ Noe 3 droCAn®1000.19 sln 0e955�2018H droCAG BOP.ware SolWans LLC ae Sell Llsting felt nodes) Ground Covers(ail nodes) Area Sol SubcatchmeA HSG-A HSGR HEG-C HSGA Other Total Ground (sq-II) Group Numbers MAI (GO) (sq-0) (sq-R) (tq-ft) (sq-fl) Cover Nu 0 HSGA 0 0 10,034 0 0 10,634 �75%Grass 0 HSG S cover,Good 116,672 HSGC PR61 0 0 78,681 0 0 78,681 Paved parking 0 HSG0 0 0 18,€57 0 0 184157 Roofs 0 Other 0 0 116,071 0 0 116,072 TOTALAREA 116,672 TOTAL AREA I NI201047 Hydro PR-REVd M201047 Hydro PR•REVt Printed M1912020 HP r+edproeCrAeDd®ky10(.enle acom p 1a daro Typel!l24-hr 2-yr a6m " NepaAdy yourcompanynomehare) PrintedRda f1r1f/a1fY8-/320,22000.,.ryM085®20 Pans 6 dreCDO0 °afn 08955 02018 H mCAD Software SolvIlons LLC Lane S Pfpe Llsting(all nodes) Time span=400.72-00 hrs,dt-O.Of hrs,7201 points Runoff by SCS TR.2O method,UH=SCS,V1 elghled-CN LI4e4 Nade In4wert Out-Invert Length Slope n DianaW.4th Height Inskie-Fil Reach iagbghyDynSter-lndMethod-Pond routing by➢y�Stor-lndmethod Number (feet) (feet) (feet) (Iyft) (inches) (inches) (Inches) 1 1P 200.00 198.00 25.0 0.0800 0.013 15,0 0.0 0.0 SuhcalchmenlpROf: Runoff Area=116,672 of 63.00hlmpervleus Runzlf DapYh$4" TF6,0 m!n CN=94 Runolf"7.65 cfs 24,733 cf Pond IP:ChamberSystem Peg%Flew202.23'Storage7,378tr fnlieyr-7.65 cfa 24.733 cl Primary-5.02ch 20,3680 Sewndary^-O.00crs Oct Outfbvr-5,02crs 20,368d Pond 2P:InfrllfallonTraneh Peak Flev=201.30'Storage-V2 c1 Inilax=5.02cfs 20,366 cf Oo Ovtvr--5.02 cls 20,257 of LIn8DP 1:DPI Inffaer-5,02 ds 20,25701 Prtmary=5.02 ds 20,267 cf Total RunoffArea 116,672 sf Runoff Volume=24,733 of Average Runoff Depth=2.64" 17.00%Pervious=19,8348r 83.00%Impervious=86,63E sf M201047_Hydro PR-RhV1 Typo III 24-hr2-yrRafnfelt-3.20" M201047_Hydro PR-REV1 Type W24-hr2-yrRefnfalh&20" Prepared by{anleryourcompeny name here} Printed 11f1012020 prepared byfenleryaurcgmpany name here} Printed 11f19f2020 HydeoCAD�10A0-19 eln 08955 Q20.18 HydroCAD Bafnyala Sa€u0ons LLC pane 7 dw0AD®10.00.10 0.Oa955®2016 H dlg04 Software SaluOons LLC Summary for Subcatchment PR61: Summary for Pond 1P:Chamber System Runoff = 7.86 ors Q 12.05 hrs,Volume= 24,733 cf.Depth=2.54" Inflow Area= 10,672 at,83.00%Impervious,Inflow Depth= 2,64' for 2-yr event Inflow = 7.65 cfs 12.08 hfs,Volume- 24,733 cf Runoff by SCS TR-20 method,t1H=SCS,Weighted-CN,T€me Spar-0.00.72.00 hrs,dl-0.01 hrs Outflow 5.02 c€s(g 12.17 hrs,Volume= 20,368 of,Men=34%,Lag=5.3 min Type 11124-hr 2-yr Ralnle4=3.20' - Primary 6.02 cfs(M 12.17 hrs,Valuate= 20,368 of Secondary= 0.00 cfs(6 0.00 his,Valuma= 0 of Area(go ON..D6scription 18,£67 08 Roofs,H8G 0 RouOng by Dyn-Slor-f:id method,Time Span=0,00-72.00 hrs,d1=0,01 brs 78,e81 98 Paved paddng,HBO G Peak EleW 202.23'6$12,17 brs Surf.Area=4,021 st Storage-7,378 cf 19.e34 74 a75%Grass cover.Good,HSoa 116.672 94 Weighted Average Plug-Flow deleneon time-125.8 min calculated for20,365 cf(62%of hsiloY4 19,834 £7.00%PeMous Area Center-of-Mass deL t1maw 65.6 min(842.7.787.1) 98,636 63,00%imporvlovs Area Volume laved Ava1l.Slaraae Storage oescdn0on To Length slope Velocity Capadly Descdpdon i11A 199.50' 3,609 or 49.44'W x 81.94'1-x 3.60'H Field A �mlnj feel) (flrg ghee cfs 14,052 cf0verall-5,053 cf Embedded=8,999 cf x40.0%Voids 6.0 Direct rntry,Direct 42A 200,C0' 6.053cf ADS StormTechSC•740+CapxI10 inside Effective Size=44.Mx 30.0"H=>6.45 sf x 7,121=45.9 of Subcatchmant PR01: Overall Size=61.0"W x 30.0"H x 7.661.YM 0.44'Overlap 10 Roves of 11 Chambers Hydre9rap5 03 200,00' 44 cf 4.007)x 7,00'H OCS x0.6 44 205.80' 608 tf surface Ponding(W01-2)(Pyramidal"ted beimv(Recaic) -r��--��- -'-;--1-i-i-i-i-f-i-t-F-hF���-��•d-�'r?'i-i-d-i-f-i-t-F-t�� nnwr f15 208.60' 280c{ SudacePondin9c6-10)(Pyramidai})sled below fRecaia) e i I I ' ' ` ' 48 205.80' 195 cf Surface Ponding(A1341 fPrfsmalfct fort he)OW(Recala) -t-I-;-J- ;-<- 0,850 cf Total Available storage ' 1 1 1 1 I 1 I 1 I I I i II I I ' 2-y€ Rdi€1fa1� J20'i (-('(-l-f Storago Grdup A crealedwilh Chamber W,zard (.i.i-i�.L_�( rfp(D�g�44s��GY_ Elevation SurfArea InaStore eum.Stdea Wel-Area ' ' feet s-g Cubic-feel cubiGfeel s-0 �11R4f1'_ QPthl=x !C{'I_ 205.80 4 0 0 4 - --- - - '-I I I I I Ci=G.0 111F11 208.30 400 74 74 401 . 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'_ _1_ _'_1_' _�_'_�_'_'_'_)_. ._`"�'. 207.00 1,400 260 280 1.461 Elevation SudArea Inostore Cum.Stara o' 4 a aroi 14ih iep n�;ie is as ar a4 ai ai+e----4s ae ss ar d4'aa aewuuc5 ee ion 0e0 (sg,n) (cublo-feet) (cubio-feet) 205.00 3 0 0 200.00 90 0 9 206.00 235 130 139 207.00 $25 58 105 M201047 Hydro PR•REV1 7ype11)24-hr2-yrRafnfall-3.20' M201047 Hydro_PR-REV1 Type 11124-hr2-yrRalnM1h3.20" Prepared by{enteryour company name here] Printed 11f19t202a Prepared by(enleryaur compan,name here} Printed 11A9l2020 IiydcoCAt�10.00.19 sin 08955�201fi BvdroCAo SOP.wara SoM.rana LLC Paae 9 HydfoCAo610.00-19 sin 08955 4f 2018 HvdroCAD Software SoIuL'ons LLG Paae 10 Device_ Routing Invert Outlet nevlces Pond IP:Chamber Syste0t-Chamber Vknxard Pfeld A 01 Primary 200'aw 15.0"Round Culvert La25,0' CPP,mearedto conform to UL Ke=0.700 ChamberModet=A€3S-„SFonuTechsc-740+Cap(ADSSlorm7ech9SC-740with cap length) Inlet/Outlet lnvert=200.01198.00' S=Doa607 Cc=0,900 E££ecuve51te=44.6"Wx30.0'H=>6,A55fx7.12'L»45.9cF 7 =0.013 Corrugated P5,smcolhlntnrlor,Flow Area=1.23sf Overall ska=51.0�4Vx39.0"Hx7.561.with 0.44'Ovedap V2 Device 202.75' 4.0'lang x0.5'breadth BroadCreslad Rectangular Welr Head(feet)0.20 0.40 0.60 0.80 f,00 51.0°Wide+0,0"Sparing=57.0'ac Row spacing Coef.(English)2.80 2.02 3,08 3.30 3.32 43 Secondary 204.50' 10,0'fong x0,5'breadth BroadCrestad Rectangular Wetr Head(feel)0.20 0.40 6,60 0,60 1.00 11 ChemberslRowx7,12'Long+0,81'Cap Length x2=70,94'Row Length 412.0"End Sionex2=84.04, Coef.(English)2.00 2.92 3.08 3.30 3.32 ease Length 94 DW e1 201.00' 12.0"Vert.orificelOrataXMID C-=6.600 10 Rows xfii.C'Mda+6.0"Spadngxe+12,0'Side Stone x2=49.W Base lMdth 6,0"Baso+30,0°Chamber Height+6.0"Cover-3.50'Field Height rlmary OutFlow Mex=5A1 cfa @ 12.17 hrs r202M'TVi L201.30' (4ynamlc Talwater) FCutvert(inlet Controls 5.0[Us 4.09 fps) 110 Chambers x45.9U=5,05%4 cr CirsmberSterage 2=6roadCrested Rectangular Weir(Controls 0.00 cis) =Orifice/Grate(Passes 5.01 Os of 6.44 cfa potential Row) 14,052.1 of Field-5,053.4 of Chambers=8,996.7 cf Stone x 40.0%Voids=3,599.5 er Stone Storage Mrtdary OulFlow Max=O.00c1sG0.00hrs KW-199.50'TW=0.40' (oynamlo Tsiiwator) Chamber Storage+Stone Storage=8,662.0 U=0.190 a( Broad-Crested Rectangular Welr(Controls 0.00 ch) Overall Storage£ffidency"61.6% Overall System Ske 01.94'x 49,00'x 3.50' t 1 o Chambers 520.4 cy Field 333.3 Cy Stone M2010k7 Hydra PR-REV1 Type lif 24-hr 2-yrRafnralf=3.20" M201047_Hydra PR-REVi Type f(f 24-hr 2-yrRalnra(1=3.20" Piepaseddy{entefyourcompanynamahere} Printed 11110=20 Prepared by{enteryoutcampanynamehere} Printed 11n912020 H awCAf1®1000.f9 sln 48955 492016 H roChll SaMrare SduUo s ELG a H d aCAn®#0.00-f9 al 08955�i 201 H roCAtl SoOwara Sah�lk s LLC a e Pond 1P:Chamber System summary for Pond 2P:Inflitratlon Trench Hydra9npf, Inflow Area 116.672sf,03.00%ImpeNOus,Inpowdepih= 208" for 2-yrevent "i' ice, follow = 5,02 cfs @ 12.t7 hfs,Volume= 20,368 of 'I'1-{.-S-I..- ..1-I.;"i'I mouno� Oulflow = 5.02cls@ 12.17hrs,Volume- 20,257 of,Allen=WA,Lag=0.0 min ltlfld--)t1 Primary = 5A2cfs@ 12.17hrs,Volume= 20,257cf 1 ;1_1_1-1-I-{.�1_.- t RousingbyCyn-Stor-Indmelhod,Time Span=0,00.72.00hrs,di=0.01his t ' 1 1 f I It9r2gF'rr �l s I ,, , , Pea$Fi8v=20i.30'012A7hrs Sud.Atea=165s1 Storage=128ci Plug-Flow detention time=4,5 min calculated for 20,257 cf(09%of tnaow) Centor•6WSss del.time=0,0 min i843.8-842.7) -;;L;f-1-`�-''t-`i-1-I- 'I �-1-f- Volume invert Avall.Stora a storage Descri lIon r , #I 197,26' 00 cf 3.0038f x 20,00'1.x 3.75'H Prismalold t- ;A ;�-t� i-i-,i 225dOvereh-25of Embedded=200of x40.0%Voids ' #2 100.00' 25 of 15,0"Round Pipe Storage Inside#1 -r i ;a E i#F A f -i-1-F i F-F,+i-_�A1_1+11_l_l- L=2o.0' ' i i i `i " i i i i #3 201.00' Bid Trench Surface Sloraaa(Pdsmattcl.lsled hafaw(Retalc) 156 of Total Available Storage t Etava�on Surf Area Inc.Store Cum.Store 1E 0]4 6 b 501111 551011 24 isisjo r2 y4000a404244 Mob E06254 MME44264e5 U?On ((eel] (sQ-n) (cubte-feel) (cublo-feel_ suM lwv�1 2g1,00 60 0 0 201.30 105 25 24 201.50 160 26 51 Cavite Routing Invest Outlet OVic0s #1 Pdmary 201.10' 200long x0,5'breadth Broad-Crested RectangularlNelr Head(feet)0.20 0.40 0.60 0.00 1.00 Coal.(Engilsh)2.60 2.92 3.04$.30 3.32 PLrlmary OulFlow Max=5.02 us @ 12.17 his KV;r,201.30'TV-O.W (dynamic Tailwater) 1=Broad-Cresled Rectangular WelreMtr Controls 5.02 cis®1.25 fps) M201047 Hydro PR•REV1 TYPO M24-hr2-yrRalnla1h3.20" M201047 Hyd%pR-RVV'1 Type V/24-hr2yrRafnfalf=3.2o, Prepared by[onleryourocmponyaarnehare) Printed 111fOM20 Prepared by Center yourcompanynamehere} Printed 11/1912020 HvdraCAtA91Q.0a10 s!n 08955 In HvdroCAO,8arvrare 86Wons LLC Peae 13, }€V roCA[1®t0.OQ14 s/n 08955®2016 Wd..A.&ffmfe$01xione LLC Penn 14 Pond 2P:infiltration Trench Summary for link t7P1:DPI liyaroyapn Inflow,Area 116.672af,83.00%ImparMUS,Inflow Depth- 2.08^ for t-yrevent Inflow a 5,02ds@ 12,17hrs,Volume= 20.257 at i - - - - - -� -" .� , s "t ® Primary 5,02 cfs 1g 12.17 hm,Voiume= 20,257 of,Attan-0%Lag=O.O n 1n . .. ? 1#fl4wA. ?r . . . . Primary cul0ow=InOar,Thna Span=0,00.72.00 hrs,dt=0.01 hrs - 66M e�,U§U, Link DPi:13N altar i 4,_ ; ; LI I;_:_:_4_i_ Ill AF a tM$�: - - arm S, T. � • I , i l, ' 1 i _J_l_i 4.LJ_' -, F- I I �-�-i-, i- IiI I o s i s e is 1,2 sezo a�a�nii ss ai - - ��a�a iz is t3 30 31 56 30 53 6J 6i 616669]a T2 E - - ri � i � Ii � lii III E i I i i l i l i i l i �i A Ief]I116iB]Oz•12���330 d111363eW�l644 Cdro6iwr3�w6z a<6e e9]O14 n,.e leevn) ' 1 M201047,Hydro_PR-REV1 TypelI724-hr j0.yrRa1nlalf4.88" M201047 Hydfo,.PR-REVl Typo£It24-hr 10,yrRelnlaf-4.80" Prepared by(enter your company namehere) Printed 1111OQ020 Preparedby(enleryo,,r-mpenynamahere Printed 111f912020 FivdroCA17Fi 1a.00.19 shr 08955 02al6 HvdlaCAri So.",vrare Solutions LLC Pe$ HYdfeCAl�1000.19 s1n 08955®2aS8 HvdroCAO Sgflware S61u9ans llC _....__Paae 76 Time 8pan=o.M.72,00 hrs,dt=o.a1 his.7201 palots Summary for Subcatchment PR01: Runoff by SOS TR-20 method,UH=SCS,Welghted-CH Reach rouf0g by Dyn-Stor-Ind method-Pond fouling by Dyn-star-Ind method Runoff 12.03 cfs @ 12,08 hrs,Va£umel 39.060 cf.Depth-4A V Su4catchmen1PR01: Runoff Area=116,e72sf 83.oa%lmpeMous Runoff Depth=4.11" ROnoffby SCS TR-20 method.UH=SOS,Welghted-CN,Time Span-0.00-72,00 hrs,dt=0.04 firs TvmUrn!n CH=94 Rdlotf=12.03erl as,968 c1 Type III 24-hr 10-yr Rainfa11.4.80" Pond I P:Chanlher9ysteln Peak Elelr-208.£0' Infl v-12.03crs 39,969cl Area(sf) ON Description Primary=11,37 cfs 35,603 N Seminary-0,00 ch Oct CNAovr-11.37 ars 35,603 or %iS7 08 Roofs,HSG C Pond 2P:InfltralfonTrench Peak EI5v=2fl1.45'Storage�Mcf Infl v--41.37cls$5,603 of 78,88E 06 Paved rasa ,HSGC Cu{sour-11.71 cfs 35.49£el 19 672 74 WelQ>75%Grass aver Good HSG O 116,872 94 1NelghledAverage Link DPI:UPI Inj -ll f,7f cf;35,441 cf 19.634 17.00%pervious Area Primary=15.7S cfs 35,491 cf 98,638 83.00%ImpoMous Area Total Runoff Area=116,02sf Runoff Volume u39,966cf Average Runoff Depth=4.41" To Length Slope Va"y Capacity Description 17.00%Pervtovsn19,834sf 83.00%u impervious=96,638 st min fool 0/fl BTsce Ws) 6.0 Direct Entry,Direct Subcatchment PR01: !{ydrograph _I I I_I-{-i_i-i-i i-i_i_I I 11- 1 I ' I I I I I : 7tr�D�tval�Mn� B�� o f e ' i i i - - ;kundfF erpl"=aila!- r I-i T'i i i i77 i 7;IC � J}fl�ai1 4'r}}' ;�`� i E 1 l t t-}-t-F-F-'ri'1-1-1-i I i i i i t qZ � ,ai1'i/161!]041]I a690]9]1355]]641 ]516 N5a 515455 L�60 E1M Bq 58]5]] ram.rr,o�„y 4 N120104Y Hydro PR•REV1 7ype III 24-(rr 10yrRefalalf=4.80° M201047 Hydro_PR-REVi Typa11124-hr 10-yrRalnfel!--4.80" Prepared by(enter yourcompanynemahere} Printed 111191202o Prepared by{entaryoufcompanynamattere} Primed 1111912020 droCADO 10.00-19 srn 06955 a32018 rtIll Software ScMicns LLC a e }lgdiaCA t.f0.00-19 sln p8955�2976 HvdroCAC Soflwate SeMkns LLC Peoe1S SumnlaryforPond1P:ChamberSysiom ❑evics Reuti laved outistDavtces #1 Primary 200.00' 16.0"Round Culvart in0avlAma= f i 6,672s1,83.00 k ImperAous,Inflow Depth a 4111' for 10-yr ovent L-25.0' CPP,mItered le conform to fl0,Ke=0,700 Inflow - 12.O3ds® 12.08hrs,Volume- 39,068 cf lalelJOullel lnvett=200.00'1195.00' Sn O.08007 Cc=0.000 Outltmv = 11.37 ds a 12,11 hrs,Volume= 35.603 of,Allen=6%,Log-J.6 min n=0,013 Conugstad PE,smooth latedor,Flov�Araa-1.23 V Primary = 1L37 CIS 12.11 hrs,Volume= 35,603 of @2 Device 202.7V 4.6'long x 0,8'breadth Broad-Crested RectangularWelr Secondary- 0.00 eta 4P 0.00 hrs,Volume= 0 of Head(feet)020 0.40 0.60 0.80 1.00 Coal.(English)2.80 2.92 3,06 3.30 3.32 Routing by OynStor4nd method,Tine Span=0.00-72.00 hrs,d1=0,01 hrs #3 Secondary 208.50' 10.0'tong x8.5'breadth Hroad-Crested Rectangular Watr Peak El6v=206.10'Q12.11hrs Svf Afea=4,288si Storage=8,728cf Hedd(feel)0.20 0.40 0.60 0.80 1.00 Coe.(English)2.80 2.02 3.08 3.30 3.32 Plug-Flovrdelonllon 901e=B8.5 min ca€culated for 35,508 er(80%orinnow) #4 Device 1 201.00' f2.0"Vett.Orifice/Grata X 2.00 C=0.600 Center-of-Mass del.dme=48,6 Mtn(e21.3-774.6) J-22roadCfested 'OutFlowMax=11.26clsa12.11hmHVV�206.10'T4V=20MT (OynamlcTanweler)Wome Invert AVOIStora a Store a DOSUI tion ert(Inlet Controls 11,20 Us @ 9.18 fps) #fA 199.50' 3,599 of 49,00'W x 81.94'L x 3.60`H Field A Rectangular Welr(Passes<81.26 eta poten8al flow) t4,052 cf CVora9-5.053 d Embedded A 8,999 of x 40.0%Vold9 =OriMcelGrala(passes<1621 ors poleaVal QOY4 #2A 200,0V 5,053cf ADS StomiFechSC-740+Capx110 Inslde#f FMOOM St7e-44.6°W x30,0"H= 6.45 srx 7.12'L=45.9 cf Secondary OutFlowrMax=0,00 cfs@0,00 his HW-199.50'7NY-0.00' (Oynamlo Taliwaler) Overall Stze=51.O-Wx30.O"H x 7,561 µ.lh 0A4'Ovedap 3=Broad-Crested Rectangular Welr(Conlrols 0.00 efs) 10 Rows of 11 Chambers #3 200,00' 44 If 4.00`➢xMOW OCS x0.5 #4 205.80' 098d Surface Pending(WOi-21(Pyramidall-lsted below(Recalc) #5 208.50' 260 cf Surface Pending(CE-101(Pyramldall lsted below(Receb) 0205.80' 195 of Surface Pending AD-4 Prlsmalic ted below ecale 0,650 of Total Available Storage Storage Group A treated with Chamber V4lzard Elavatton Sur.Arna Inmetore Cun sfore Womea (feel) (sg-8y (tublo-reef) (cubio-feet) (sa-n) 203.80 4 B -_ 0 4 206.30 400 74 74 401 207.00 1,500 624 698 1,604 Elevation Surf Area Ina.Stdre Cum.6tore Vr'et.Area (feet) (swR) (cuhlo-feetl (wblo-feet) (sq-M 206.50 4 0 0 4 207.00 1,460 260 260 1,401 MOV21lon Sud.Area ino.Store Cum.Sl0re (feel) (M-n) (u Alcfeef) (cublo'1600 205,80 3 0 0 206.00 90 9 9 208.80 235 130 139 207M0 325 56 105 M201047 Hydro PR•REV1 Typo lit 24-hr fO-yrRainfall=4.80' M201047_Hydro„,PR-REVi Type 11)24-hr 10-yrRafnfathii-80° Prepared by{enleryodr-.n, nyname here} Printed 11AW202o Prepared by{enter your companyy name here} Primed 1 111 0120 20 mC ®1000-l9 e,06955 d52016 rpCAd]Software Solullons LLC a 1'.^draGAO®100a-09 s1n 08855�295ti HVdraCAO 3c4ware Solelwns LLC Pone20 Pand 1P:Chamber System-Chamber Wizard Field A Pond 1P:Chamber System Hydrparaph ChamberModel-ADD StormTech8C•740iCap(ADS6larm7ech9SC-740vmhcaplength) Effective 6Ize=44.6"W x 30.0`H->6.45 s[x 7.12'L=45,9 cf °biSPi 0 11 Size=61.0'Wx30.4)"H x 7.56Lwith 0.44`C"4a 'r:-4-i-F;-i-1-�-i i-(--I-i-ii-i-i-�i-i-t�i-i-E-�-t` p 'I11R�1ksAYid.. . . ..2 f- 51.0"Wide+6,0°Spadng a 670 GC Row spacing „ ' _ � �-�-�........ -�-� � t s- 11ChamberslRowx7.12'Lone+0.61'Cap Length x2=79,94'RowLenglh+12.0°Fadstonax2=81.94' F#- BaseLengtht-F�-i-t-��-t-F-�-i- tORmvsx61,0"Wde+6.0'Spadngx9+12.0°Side Stone x 2 o 40.00'Base Width ° _ _ _ _ ' «-' ;_' _;�;- :-a-...a_S-L�-,- 6.0"Base+30.0°Chamber Height+6.6"Cmar-3.60'FleldHelghl �i-.•ram-=- r ' 1_L L y, t1OChambersx45.9cr-6,053,4cf Chamber StoragerW�_r _, r�y'Y i-i-��-�-r-r�'i-f- 1 14,052Aof field-5,053Aof Chambers-8,008.7of atone x40.000Volds=3.60Aof Stone Slorage a Chamber Slorago+Stone Storage-8,652.9 of=0.199 at Overagstoraga Efddency=81.6% now Overa6 syslom Slze=81.84'x 48.00'x 3.50' p 2 4 6 a 5a1311f656]OYeid]d99a63I]Ia635daU U!e49:a 6]61 F.6530e6Pa1 Ed 6d7p]] i l O Chombers 520.4 cy Field 333.3 cy Slone M201047 Hydra PR.REV1 Type 11124-hr fDyrRaFnfafl 4.80' M201047_Hydro PR-REVi Typ©Af24-hr 10-yrRalefalr4.aa' Prepared6y(anleryourccmpanynamehere} Printed fi119@020 Preparedby(enteryovroampanynamahere} Printed W1912020 reCADg 10 Mlli sin 06955®2018 H droCA6 Sogvrare 3olullons LLC a e droCAD®19 00-19 SQIWions LLC s 2 Summary for Pond 2P:Infiltration Trench Pond 2Pt Infiltration Trench [00)Wamfng:Raul>4in may require smarierdt Or FlAer Rouling _ _ _ kyd%q'H' fnflaw Area= 116,672si,83,0MImpervious,Inflow Depth= 3.66' for%yrevent is -- - - ' '-'- - --.:r-:-;-t-.1r;;<-<��y.-t-�-* pear Inflow - 11.37rtse 12.11 hrs,Volume= 35,603 cf s - l - - - ' ��tr+f)VIhj4�rra?'� -yr7,r'� f,"OWgaw = 11.710sQ 12.12hrs,Volume= 35,491 c/,Alten=096,lag>0.6 min Primary = €1.7105(g 12.12 hrs,Volume= 35,401 ci rr' T. RoulSng by Dyn-Stor--Ind method,Time Span=0.00-72.00 hrs.dt--0.01 bra i;01'8 2Fz r�i' -4-�-t�i-i-i-i-t-F-�-�?-i--I-i'i-F-r-r-i i i-r r-r-r Peak EleU 201.45'@12.12 hrs SUd.Afe8=205sf Storage-Mcf -��_�- ; i , i-1-t-F-€ Plug-Flow detention time=3.0mfn calculated for35,491d(iM%oflmlam) 7 ;- -;-�-�-} Center-of-Mass del.tine=0.7 min(MO-821.3) _ - _ s . . L Volume €nNed AvalL scdStora a Story a De flan a - - - - --- - - - - - of 197.25' 80 of 3.00'W x 20.00'Lx 3.76'H Prismatoid < ' :' __ _F_may _ _�_F-' 225 of OvoreEf-25 cf Embedded 200 or x 40,656 Voids - #2 498.00' 25 of 16.0'Round Pipa5loragolnside#i #3 201.00' 51 of Trench Surface Storaa Prismatfc W4d below ecalo r " y 156 ct Total Available Storage ax s e a ro is ii is+ixii�a:e�au a�a�ea armai qa+a<smai s<xsemaiu se sa you Elevation Surl.Area InaStore Gum.Slore _......,(feet? (sa-A) (cubic€eet) (cublo.feel) 201.00 60 0 0 201.30 105 25 25 201.50 166 26 51 Device Routirip Invert Cullet Do%ices #1 Primary 201.10' 26.0'long x00 hreedth Broad-Crested Ractangvtarwerr Head(feel)0.20 0.40 0.80 0,80 UO Coef.(Eng[W)2.80 2.02 2.08 3.30 3.32 rlmary OutFlow Me"-1,70cis@12.t2bm hVP201.44'7V1-o.0W (DynernicWwater) =8read•Crested Rectangular Wetr(Welr Controls€f.70 cfs(!p 1.70 fps) M201047Iiydfa�Pi Type W24-hr10-yrR81nfa0=4X0" M201097_Hydro_PR•REV7 Typo W24-hr2CryrRainfall=8.00" Freparedby{enleryaurcompanynemeherej 8rinled 11/1912020 Prepared by{enleryourcompanynamehere} Printed 11110Q020 H droCAOes 10.00-19 shr 06955®2016 N droCAO Software So fens LLC a 0 23 j4vdmCA0910 00-79 srn 08955 432916 HvdraCAD Sat ware Soluunna LLC 124 Summary for Lf nk pPl:pP 1 ,"me span=0.00.72.00 hrs,dt=0.81 li 7201 points Runoff by SCS TR-20 method,i11i=SCS,Mighled-CN Inflow Area a i t6,e72 sf,a3,0a%Imparvlous,Inflow Depth- 3-W for 10-yr event Reach rou8np by OynStor•Ind method-Pond routing by oyn-stor-Ind method in9ow = 11.71 cfs@ 12.12hrs,Volume= 35,491 cf SubcatchnlemPRa1: Ronof#Area-116,612V 83.00%IrnpWou3 Runoff Oeplh=5.30" Primary = 11,71 cfsQ 12.121 V01vme= 35,491 cf,Allen=O%,Lag=O.Omin T".Orntn cNn94 none"-5,28cis 51,497 cf PrimaryotAllow=Inflow,Time Span-0.00.72.001dt=0.01his Pond 1P:ChamberSystem Peak Elev=2o6.70'5lorage=9j"0InBow=i6.28cfs51,497cf '.. Link l i Pririmary=11.95cfs40.696d Secondary=2,48ds E37ef Outikv--14.43cfs 41.132cf Hyamerapn Pond 2P:lntiltrationTrench Paak FW,201,45'Storage=1490 inflaw=11,95 cfe 46,696 cf Out8M4--12.16 cfa 48,484 cf 1ILL 1_�_i_�.t.i_.,_i_,_ ar lnflow=14.66 cfs 47,021 Lf Link APi:PPi1x -:-:- ^'t;�K1f?�Y Prlmary=14.56 cfs 47,021 cF � i � iTotal Ranoff Area=i18,8725f RunoffVofume=61,d97of Average Runoff Oepfh sz5.34"- --- - ' i L f7.00;6 POrvlaus=18,834 sf 83,00%fmpervlous-96,83asf T'!-f't"f�Yi��-i��^ LIALL 4-1 _ 1 1I 11 _ a z 4 e e SO rxl/ie tela]3]4]6]ea1311/a8 e64x 4x 444619=A Sl ei F9 a8 re 61 a4�6BTe T] nma lxew.l ' M201047 Hydro PR-REVi Type11f24-hr2byrRafnfaf1=6.00" WNW Hydra�PR•REV1 Type 1N24-hr2b-yrRafnfafl=6.01 Prepared by(enleryour company name here} Primed 11119f2020 Prepared by(enlaryour company name hare} Pdnted 1111912020 H droCAD�111 .1.In,08955 4]2016 H droCA€l Software Solutions LLC a raCAO$v tO.ORtB s/n 08955®2016 H foCA4 Scaxara Soiv@ans LLC Pe Summary for Subcatchment PR01: Summary for Pond IN Chamber System ' Runoff = 15.29 Use 12,08 hrs,Volume- 51,497 cf,Oepth=5,30" Inflow Area 116.672 sf,83,00%Imperviou3,Inflow Depth= 6.30" for 25-yr event Inflow = 15,28 cis(M i2.08 hrs,Volume= 51,497 cf -72 Runoff by SCS TR•20 method,lfH=5C3,Mighted-ON,Time Span=0.00 .00 bra,dt-0.01 hrs Outflow = 14.43 efs @ 12.11 hrs,Volume= 47.132 cf,Allen=6%.Lag=1.7 min Type III 24•hr 25-yr Ralnfe8=6.00' Primary = 11.95 c(s a 12.11 hrs,Volume= 46,69E cr Area(an ON Secondary- 2A8 cfs0 12.11 hrs•Volume- 637 cf eescd IWn 18,157 98 Roofs,HSG C Routhlg by Fyn-Star-Ind method,Time Span-0.00�72.00 hrs,din 0.01 bra 78,e8t 08 Paved paWng,HSG C Peak Elav=200.70'C 12.11 trs SuffArea=b,451sf Slorage=9,186cf 19034 74 >75%Grass cover,Good.HSGC 116,B72 94 44�ighled Average Plug-F[aurdotanllon tlm¢-85.5 min calculated for 47,126 Of(92°.6 of inflow) 19,034 17.00'b Parvlous Ares Center of-Mass de4 time=42.0 min(Si0.5-768.5) es.838 83.00%impervious Area Volume Invert Avan.Sloraoa Storanet)es dudon _ 7o Lenglh Stopa VeWc)ty Capacity Description #fA 199.50' 3,599 cf 4$.00'W x 81.94`L x 3,50'H Field lmltl) !feel)_ (�Rn (Meal (cfs) 14.052 cf Overall-5,053 clEmbadded=8,009 cf x40.0%Voids B4O Direct Entry,direct @2A 200.00, 5.053 cf AOS StormTech SC-740 Feapx 110 InsMe#i Effective She=444'W x 30.0"H=s 8.45 of x 7.12'L-45.9 of Subcatchment PR01: Overall Size=51.0'W x 30.0'H x 7.WL wflh 0.44'Ovedop 10 Rows of t1 Chambers tiydrograph 43 20 AN 44 ci 4.00`0 x 7.00'H OCS x 0.5 _ #4 205.80' 698 c€ Surface Ponding(INQ14)(Pyramidalflslodbmlow(Recalc) e I j n 45 206.50' 28acf Surface C9•tl ramidal Isledbetovr ocalcJ -i• '�l•'''-T- 5 �6 205,80' 195 cf_Surface Pondlntl lAP-0)SPrPfsmeifc)Js3ed below(f2e�caFc) [- r4 9,850 rd Tola3 Available Slerege -'s�•�TrRairtfall='s:eo'F- -F-), Storage Group A created with ChambrlNirafd -; 1,'IijO�f 0�11}?je�" 1- $ -jG�- Elevation surf,Afen fno.Slore Cum'store Ml.Area s , -F-�-}-F- -- -;;i 1-44A-1-1-f-FF- - ��5� �� E S}3�3� {feet! (sa-01 (cub!o-feel)_ (wbIo-feeil �--k _�_ ,_ ,_,_,_,_ 205.86 4 0 0 4 -1-TC��,�hl�pl{_ 206.30 4DD 74 74 401 c -F-�-i-}- ,-'- -1-i'#-i_1-1-i-{-F't'f'(-;-'�-F'j',-'ri- . .. =. 207.00 1,500 624 69e i,604 _ 'T Elavalian Surf Arca Ino.Stare Cum,Stora Vkt.Area _ (feel} (sC-fll (cublo-faell {cvb'aTeetl (50-ft7 irli ,l i1ffF1tFS�, i ,i1i11 i i '-'-'- 207.00 1,480 280 280 1 6 Novalbn SurLAma Inc Stara Cum.Store te111�1a19]CY]]�Mji3eTTy4�a u�y)tj5p53545BF950pxp]Wy 2 feet -ft cub1cfee1j (cublo-feet 205.80 3 0 0 206'Ga 90 9 9 206.80 235 130 139 207.00 325 56 195 M201047 Hydro PR-REV1 Typo h124-hr 2&yrRalnfal".00' M201047_Hydro PR•REV1 Type III24-hr 25-yrRalnfalh6.00" Prepared dy(anleryeur company name here} Printed 1111012026 Prepared by{enter yourcompany name here} printed 11l1912620 HydaoCAC39S000-19 e,a 00955 -21&HydraCp➢Sofavare Solutlahs LW _.___P_aa_e_27 vacAP®10,00-19 On 08955®2616 drgCAO SOO+vare Salullons LLC Device Routiall Invert Outlet Devices Pond 1P:Chamber System-Chamber Wizard Field A at Primary 200.00' 160"Round Culvert L-25,0' CPP,mileredtoConform tO1111,Ke=0.700 Chamber Model-ADS_S1anmTechSC-740+Cap(ADSSIormTechfisc-740wtthcaplanglh) tnlel l Outlet Invert=200.00'1198.00' 6=0,08007 Ca 0.900 EffetSve Size=44.6'Wx30.0'Ha>6.45sfx7.12'L=45.gcf n=0.013 COrrugaied PE,smoolhlntedor,Flow Area=1.23sF OvemO Stza=51.0"W x30.0"H x7.6B'Lwhh 0.44'Ovarlap - #2 Device 1 202.76' 4.0'long x 0,w breadth Braad orasted Rectangular Weir Head((eel)0.20 0.40 0.60 0,80 1.00 51.0'WAD+6,0"Spacing-67,0'GC Row spacing Caar,(Engtish)2.80 2,92 3.08 3,30 3.32 03 Secondary 206.60' 10,0'long x0.6'breadth 8toad-Crested Rectangular Welr 11 ChamharslRawx 7,12'Long+0.61'Cart Length x 2=79.04'Row Length+12,0"End Slona x2=6f.94' Head(reel)0,20 0.40 0,60 0,90 1,00 Base Length Ceef,(English}2,89 2.92 Vla 3.30 3.32 #4 ❑oAce1 201.00' 12.0"Vert,O0ficelGraleX2.00 C=0.600 10 Rows x51.0"Wda+6.0'SpacAngx9*12.0"Side Stone x2=49,00'BaseWdth 6.0"Base+30.0'Chamber Height+6.0'Cover=3,59 FIeW Haight primary OulFlaw Max=11.94 Cis @12.11 hrs HW�296.70'Tlry=201.46 (Dynamic TsUaler) iE-Culvert(Inlet Controls 11,94 cts C 9.73 fps) 110 Chambers x 45.9 of-6,053.4 cf Chamber Slorege d_Crested Rectangular Welr(Passes<104.17 cis polantlal How) .dfiwGrate(Passes z 17.24 cis potential How) 14,052.1 tf Field-5,053,4 of Chambers=0,998.7 of Stone x 40,O%Voids=3,699-5 of Slone Storage Lcondary OulFlow Max=2.46 dor§12.11 his HW=200.70'"14-0.00' (Dynamic Tallwater) chambersloraga+Stone Storage=9,652.9 of-CAN a1 3=Broad-Crested Rectangular Wair(Welr ConlroSs 2.46 cls @ 1.24 fps) Overall Storage Llficiency-61.614 Overall System Size=61."x 49.0V x 3.50' 110 Chambers '. 620.4 cy Field 333.3 ty Slone PA201047—Hydro—PR.REV1 Type)1124-hr25yrRalnlal1=6,0a" M201047 Hydro PR-REV1 Type 11124-he25-yrRalnfall=-0,60' Prepare dby(enter your company name here) Printed1111012020 Preparedby(entoryour company rt here) Printed Mignon LjydroCAO®10.00.1g z10 06955 m2Q16 HydroCAO SaM2re SQIuwrs LLC Page 29 droCADO 10 00-19 On 06955 02018 H droCAil Serpyare SolWians LLC Page 90 Pond 1P:Chamber System Summary for Pond 2P:Infitiralfon Trench 11}Mrograph - - - - - - -- - - 1901 Mming:OolrlaOfn may require smatter dlor finer Roming ul_,_��_1' oem. 67 Wamfn 0.n5 a# ) g: p Ifons may require smatter dt or Finer Routing(severity--4) tngow Area= 118,072 sf,83.00%Imperv€ous,inflow oep0l= 4.79' for 25-yf event € ow = 11.05 e(s @ 98 12.11 hrs,Volume= 46,5 of OVTOW = 12.iScfs 12.09hr%Volume= 48,484cf,Allen- ,Sag=O,Qmin - - '-- t,-fit¢[ ie 9 G� 4" Primary = 12.i0 cfs @ Q%t2,Qg hrs,Volume- 46,484 of 1 -- - - i-, t _ -1 ;-`_.-�, Reuling by oyn-Sior-Ind melhod,Time Span=o,Q0.72.gO hrs,d[=O.QS himtt _L_1 -i peak Elev~201,45 2,09 1 -F-4a_i_:.�1'i_`�-i_`_ _._��-S_+_F,_,-+��-rs,_ '�i hrs Surf.Area=207 sr Storage-148 of , i_t x 1_�_y�_i_Fy i_i_F_�i_ Plug-Flow del on don time-2.5 min calculated for 48,484 of(100%of In now) Canter-of-Mass del.time=0.7mitr(8i2,i-811.5) „ r;- -f:-i-f++1-+-ri-+-F S-+-F }-}-�i-+-F-i- ' €-Fi-i-+i-i-}-}�-}- Fi-#-F-Fi-I-F-;-ar Volume (Hoed Avag,stateae Storage Description 60 of 100511 x 20.00'L x 3.75'H Prlsmato€d - 225 cf Overa6-25 cf Embedded-2o0 et x 40.0%Volds 42 196.00, 25ct i6.9"Round Pipe Storage Inside Ni t L=20.0' a x i e dlou tstetexaa zax�a eoats�ee33w,12 :a raws�snsesesae:e.eaee rau � �S 201,Q0' 51 cr Trench Surface Staraga JPdsmatlelt5ted helm(Rewto) 156 of Tola(Avallabla Storage Elevadoa Surf,Area Tno.Slare Cum,Store (sq-ft) (cMWotrfeel) (eubTo-reel) 201.00 60 0 0 201.30 105 25 25 201,60 "160 26 51 o.ay;c_e Rou0ng Invert Oullet nevlces 41 Primary 201.50' 20.0'long x 0.5'breadth Broad-Crested RectangularlVaFt Head(roe;)0.20 0.40 0.60 0.80 i.00 Coef.(English)2.80 2.02 3.08 3.30 3,32 primary oulFfow Max=12,09 of$@ 12.09 hrs f MV=201.45'TW-0A0` (oynamlo Tagwate) 1=Rroad-Crested Rectangular Welr(WelrControls 12.09 Us @ 1.72 fps) ' I M201047 Hydro PR•REV1 Type III 24-hr 2&yrRelnPafk6.00" M211 047 Hydro_PR•REV7 T]pe 11124-hr 26-yrRalnfal1=6.06" Prepared 6y(enter your company name here} Plated 11118P202o Prepared Ey(enter your company name#sere} Printed 1 111 0120 2 0 �.•rdreCAp�10.OQ4g s!n ee955 92016 HvdraCAp Setwara Solutfons LLC Page 31. fi droC ®te 0049 stn 06955®2f31fi H roCAl7 BoRV era Solutlaas LLC S Pond 2P:Intlltratlon Trench Summary for Link DPI:DPI NpdrograpS, Inflow Area 118,872sf,83,001AImperAous,1nlmvDeplh= 4,84" for 25-yreveni Inflow F 14.56cfs® 12.11 hrs,Volume-- 47,021 of Primary 14,56 eta @ 12,11 hrs,Volume= 47,02f cf.Attan=o%,Lag=O,Omin ' „InUov✓A1ra-�!ta72_sf Primary oWflow=Mew.Time Span=0.00-72.00 has,dt=o.ol hrs AMA 1 i- l-t-F'r 1-i--r i z-i- - -1r.�fAfrd'rt]�Erlr C� Llnk DPI:DPI r - -- - - - - - - - -IOp A - 1 -f'1'i' 'i-�'f fi-l-i-i- f-f l'` �-f _ _ . _ _ _ __ _ I ; A, - _� r l i �,-.-i-1-t-f-i . -�-i-f-t-�-F-� 1 t 6 61611111E ss id22 R496 TB 3]31�1]638131E AF t8 t6'A6]6/5566 tA6]BI 686a T67S _ - - - - -�-�-F-1�i i i i i I i i i i i i_i_1-t-� i Time(hotel �i.�_ 6 -�i-3- F-4, 3� E4FF ii f fF ,` l{1 §kF� , 6 1 A f0111/16 IB WA R5161B:0 Tml S8 J34i/1M<616606E 5S 58 L-060616d 1666)6YI M201047 Hydro—PR-REV1 7WO III 24-hr 100-yrwnfall=e,e0" M201047 Hydro_PR-REV1 Typo 1f724-fur f00 yrRalnlaN=8,60° Freparedhy(enleryovrmmpsnyynamehere} Pdnied tif1972020 Preparedby{enteryourcompanynamehere) Printed 11118f2020 draCAr1®10.00.1$shr 08955®26F6 raCN]Sa8n2re Solutions LLC ace 33 droCAD®10.00-19 sin 08955*20f5 H droCAD Stamm 6010ons LLC Eno g Time span=0,00.72,00 furs,dt=0.01 furs,7201 points Summary for 5111JQatchnte nt PR01: Runoff by SOS 7R-20 method,UH=SCS,Welghtcd-CtJ Reach routing by€?ynStor-Ind method-Pond routing by D)m-Slor-Ind method Runoff a 2428 cfs @ 12.08 hrs,Volume= 79.603 cf.Depth=7.86" SubcalchmenlPR01: RunottArea»716Tc72sf8.0 fn (:bl94 Ru o Runofffs 6603cf Runoffby SCS TR-20 method,UWSCS,Weighted-CN,7Une Span=0,00-72,00 hrs,dt=0.01 hrs Tc=S,O rKn CN=94 Runoff-22.26 crs 76,6Q3 cf Type]f124-hr 100.yr Reinfa8=8.6W Pond l P:ChanaberSystem Peak Eler-208.96'Storage=9,724 of Inflow-22.2S cfs 76.03 cf Area ON Description Primary=12,23 cfs 67,867 or Secondary=9.25 ds 4.271 or Culf1�1,49 cfs 7z238d 5 18,157 88 Roofs,HBO G Pond 2Pr lnfiltratfonTrench Peak Elev-201A.T Storage=149cr Jnnnvr12.23crs 67,067 cf 76,681 98 Pavred parking,HSGG Cut4rr 1224 cis 67.855 of '19,834 74 >76 A Grass cover,Good HSG C 116,872 94 WefghledAvemge Link DP1:DPI lnnavr21,49 d-72,126 or 10.434 17.00%Pervlous Area Pdrrury-l-49 cfs 7$126 of W.Baa 83.00%impervious Area Totes Runoff Area=10,672 sf Runoff Volume-76,603 cf Average Runoff Depth=7.88" To Length Slope Velocity Cepacily Description 17,00%Pervleus=19,834sf 83.00%Impervious=96,8380 min feet Rift glsec cis 6.0 Direct Entry,Direct Suvcalchmont PR01: Hydrogra�n 16 44±4- 1-4 e `F �t 4' e 2 4 Aatn+l]191619]O a2]948]835 i= j5 as�](154431B F03254 b6�$p 4J 696a[d l0]3 lkm!hoar) I M201047 Hydro PR-REV1 Type W 24-hr 100-yrRafnralr8,60" M201047^Hydra_PR-REVI Type A124-hr 100-yrRafnfal1=8.60" Prepared by{enter your company name here} Pdnied 11N912020 Prepared by{enleryour company name here} Printed S 111012020 HvdtoOAn�10.00-19 61n 00955®2011 IT&I'le O oft.Solutions LLC Page 35 M*oc O®70.tl0.79 afn 48955 m2018 HvdtoGAD SOOware Selvllens LLC Page 38 Summary for Pond 1P:Chamber System Devlca HauenA Invert Outlet Devices Nf Primary 200.00' 15.0"Round Culvert InlowArea= 118,672sr,83.00%Impervious,InlowDepth- 7,88' for I00-yrevent L-25.0' CPP,m4eredtoconformtofill,Ke=O,700 Inflow = 22.26 c£s(o 12.08 hra,Volume= 76,603 0 Inlet/Outlet Invert-200,00'1198.00' 8=0,0800'I Cc-0.900 Outflow = 21AD cfs 12.11 hrs,Volume= 72,238 cf,A1len-3%,Lag=1,3 m1n n=0.013 Corrugated PE,smooth Interla,Flow Area-1.23 sr Primary a 12.23 ds 12A 1 has,Volume= 67.96701 tt2 Devlco 1 202.76' 4,0'tong x 0.6'breadth Broad-Crested Rectangular Welr Secondary= 028 cfs a 12.11 We,Valuma= 4.271 cl Head(feet)0,20 0.40 0,60 O.Se 1.00 Coal,(English)2.80 2.02 3,08 3,30 3.32 Routing by DynSlor-Ind method,Time span=0.00-72.00 hrs,dt=8,01 hrs A3 Secondary 208,8a 100 long x 0,5'breadth Broad-Crested ReclangularWelr Peak Elev-200.9V @ 12.11 bra Sud.Araa=7.CO9sf Storage=9,724cf Head(feel)0.20 0.40 0.60 0.60 1.00 CoeC(Engllsh)2.80 2.02 3.08 3.30 3.32 Prug-Flowdetentlon llme-67,4 min calculated for 72,238 cf(94%of InOdw) #4 Device 1 201.00' 12.0"Vert,oritice101ate X 2.00 C=0.600 Center-of-Mass det.tlnte=35.0 We(704.7-759.7) • pprimary OvlFlow Niax=12.23 cfs g 12.33 hrs HV-200.86''Mk201.45' (DynemSc TeELvelerj Volume Inved Avall.Slorage Slofaae DesednQon t=Culvert(inlet Controls 12.23 cfs®9.07 fps) g1A 109.60, 3.699 cf 49.00'W x 81.94%x 3.00'8 Field A 2=&road-Crested Rectangular Weir(Passes-t14.67 cfs potential Bow) t4,052 cr Overall-5,053 c1 Embedded=8,999 at x 40,11%Voids -OrificelOrata(Passes<17,67 cfs potential flow) #2A 2a0,00' 5,053cf AeS_EtormTecliSC740aCapx110 inside*1Eff econda OutFtawl4lalr-9.22ds i2Slhrs HW=208.98'TW=0.09' namlaTaOwale overallSheetive e51.08'Wx30.0"H=>0.45sfx7. Overlap -3=Bread-Crested RectangularWe)r(WelrControls0,22efs 2,01 fps) 0 overall Slze�51.0^W x 30.0.H x 7,66'Lwl:lt 0.44'Overlap 10 Rows of 11 Chambers 03 200.60, 44 cf 4.00'0 x 7.081H OCS xO.B #4 205,80' 69S of Surface Pending(WQ3.2)(Pyramldal�isied below(Recale) its 206.50' 200 of Surface Pending(CB-0OI(Pyramldal),Isled below(Recate) 0 205 80' 195 d Surface Pending(AD41 fP_riamadeLtsled below(Reca1c) 0."0 d TatalAvallable Storego Storage Group A created Wit Chambor Mard Elevation Surf.Area Inastore Cum.Store WOArea (feat) (sa4f) (cubic feet) (cubio-reet) (sg-fl), 205,80 4 0 0 4 200-30 400 74 74 401 207.60 1,600 624 698 1,504 Elevation Surf.Area W-Wfo CumBlcro 1Atet.Area (ree0 €sg-11 (cublo-feell (cublo-feet) (so-0) 208.50 4 0 0 4 207.00 1,400 260 200 1,401 Elevation RmlArea Moslem CumBtOre ((net) (so-0) (cubicfeell (cublo-feed 205.80 3 0 0 206.00 00 9 9 206.80 235 130 139 207.00 325 50 195 - M201047 Hydro PR-REV1 Typo It/24-hr 100-yrRalnfa11=8.fi0" M 201 047 Hydra_PR-REV1 Type III24-hr 100yrRaFnfalt8.60" Prepared by(en[eryourcompanyrlamehare3j Printed it11812020 preparodliy{antery Our campanynamehere} Printed 1111912020 HvdroCAfl®,a..19 sh103M.2I f,Hw ir.Z SORware Solutions LLC Page 37 f roCADd 10.o0-19.08955®20fe HI CAU Scoxare SOhmans me Pace 38 Pond 1P.,ChattiberSystem•Chamber1hrizard Pteld A Pond iP;Chamber System ChamberModel=A05 StomnTechSC•740+Cap(ADS S;ormTech95C-740wnh cap length) IHydrrgnph rhecllve slze=44.0"Wx30,0"H=>0.45sfx7.12'L=45.9cf "Y(1'j" Cveratl Site=61.0°W x30.0"H x7.58'LwI0t 0,44'Ovedap 4_44 ' , ' ' 'IT.-;_;,._._;_' ' ' ° _, 51,0'Wde+6.0"Spacing=67.0"GC Row Spacing __i_i _ _ __ _ X P + ,$a 0, g 1£ChamhemWwx7,12'Long+0.81'Cop Length x2=79.94'RowLeaglh+12.WFmf Stone x2r81.94' - - --U11 - - --' tg qe J� +i;- Bass Length 10 Rowsx5l.o^VNdo+6.0"Spacingx9+12.0"Side Slonex2=49.00Base Wdth - -. .. -;; �r1- r -;-:T;-+-iz;- 6.0"Base+30.0"Chamber Helghl+0.0"Cor=3,50'Fleld Helght £10 Chambers x45.9cf=5,053AdehemberStorage 14.052.1 of Field-5,053A Cf Chambers=8,000.7 ctStone x40.01.Vohs=3.599.6 of Stone Storage Chemher5larage+Stone Storage=8852.9 U=0.199 at _ a ,• Ovemg Storega Eglcfency-61.6% overall System Size-61.94'x 49.00'x 3.60' t 110Chambers ega36e Oaa7072 620.4CyField "ems �Rl 333.3 cy Siena M201047 Hydro PR-HFV1 Type11124-hr 100-yrRa1nfa£r8.80" M201047 Hydro PR•RVV1 Type III24-hr 100-yrRaW89­8.60" Prepared by{anieryour company name here} Pdnled 1111912020 Prepared by{enteryour company nema here? Printed 111f0f2B2a H roCAO®10.Of, s!n 08955.2016 H draCAO Software Solutions MC a e,39 FtSdroCAO®10,00.i0 sfn 08855�2018 HVdroCAD Safavale 6oINlona'LC Pane 40 '. Summary for Pond 2P:Infiltration Tronrh Pond 213:Inflltration Trench Ilydrograph goo]WamN;ctoul>glnmayrequlresmaferdtcrFlnerRouting � I s.1-.-'-..i-i-t-r-("t'"fy-'r.i--'i-i-t-g-(rTTi-�-i-r�r��r AIM InOowArea= 116,672sf,83,00461mpervlous.In0owDeplh= 6.09" far i00-yrev001 to �'-�-,"' g•F-�-��-4- -f.�.}-f-f.-i-i�-f•g-}, -�=- F- €n0aw - 12.23crs@ 12i1hrs,Volume= B7,967 cf _ _ _r_�_�_�s_;.,_._�_._(-u:111fJ4yY.�ii4 �` oulftow - 12,24 cfs(M 12A I hrs,Volume-- 67,855 cf,Allen=0%,Lag=0,2 min _ _ _� i :_ 1 ) '_ _ _; k 66�'s-+ '4. &? Primary = 1224 cfs a 12.11 Kra,Volume= 67,855 of �' '�Y Roullnghy€3ynstar-fndmelhod,TtlneSpen=0.00�72.00hrs,dP0.Ofhn; -�;-i- •}-F ,-:_W-€-F-F i-�-�-i-P-F� ;-1-44-F-€-`r+ Peak Elev=291A5'@12Ai hrs Surf,Area=208 sf Sloraga=t48cf _11_ -,-�-i-;_i_(_�.x_�_t_i_r_(..�-�_� a % Plug-Flowdelenlion t1rne=l,9 min calcufa€ed for 07,055 d(100%of ingov4 - Cealer•of--Mess VeWnta Invert Avail&lorago Storage Oascdp9on '-T-' ''1 1 1 k-���'~'_r_g r L 41 107,25` SO of 3.00W x 20.0o'L x 3.75'H Pdsmatold ; - - �� -1•�-�-;��-�-��-I 225 cf Overa8.25c1Fmhedded=200af x40A96Vokts a ;'$ - "<``-�-- -F i 1 1-.-g--F 1£2 108.139 25 or 15.0"Round Pipe Storage inside*1 L=20.0` 03 20€A0` 51e1 TrenchSurfacaSlora a 1prjsmaticjjstedbelow ecale 4' 158 cf Total Available Slerege o) a raia i4 ro to wn i4:e ze as 9t a4�8 43 42 44 A 48 aesz as ss sawaze4 ee sa zo)s nma ina 0 Elevation SOrf.ArEa Ino-51ore Cum.Slora (eel •fl wblafeel cula!�feet MA0 60 0 0 201.30 105 25 25 201.50 160 20 51 Pevlce Rauttng Invert outlet Devices 41 Primary 201,10' 20.0'tong-x0.6'breadthl3road-CtestedlReclangu€arWe€r Head(reef 020 0.40 0.60 0.80 IA ooe1,(Engllsh)2.80 2.02 3.08 3,30 3.32 ppdmaryeutFtowMax=12.23cfs®1211 hrs HVJ-201AS'TW=0AW (UUynam!aTelwa€er) 1-1=13road-Crested Rectangular W elr(Welr Controls 12.23 cfs C 1.72 fps) - M20iD47 Hydro PR•REVJ 7ype If/24-hr ID0-yrRalnfaIP8.60' Prepared hy(enter yourcompanynamehere} Printed 11lf9l2a20 Hyd,oCAM 10,M19 Wn 09955®201&HvdroCAD SOY.�tare,Solulkns LLG pans 4 f Summary for Link DPI;DP1 Inflow Ares= 116,672 sr.113.00%Impervious,Inflow 0 apt h- 7,42" for 1000.yr event Inflow - 21.49cfs@ 12,fihrs,Volume= 72,125 cf Admary - 21,49 Us@ 12,11 hrs,Volume= 72,€26 cf,A11en>0%,Lag=0,0 an Primary Or4Ro W=Inflow,Time Span=0.00-72.00 We,d1=0.0$hrs Link DPi:DPI frydrograph 24 -1-1444 =C - CCU]:,,a_:_€_I $1 µ{ FHF '31I-�-f--�y •I•i FFryT11fs 10 e F 6 1013111815101]14 R6 A 3a 33 Jd k h N 15 N e36 4 43866&6 4370)3 h r @amyl Proposed Commercial Development 419&435 Andoverlitreet North Andover,MA 841er lob Number;M201047 November 19,2020 Rational Pipe Sizin Celculallons !. H WQU,l SYSTEM 0424 0.95 0.12 0020 010 001 012 6 48 069 12 0940 HOPE 0W2 772 9.s3 C13-5 COS-1 0199 095 0.19 0033 0.30 001 020 6 4s 095 12 0040 HOPE 0012 772 983 DMH-I Ot:2H2 0366 095 035 0044 030 001 026 6 46 173 12 0028 HOPE 0012 667 �8.37 OMH3 OMH4 0749 095 067 0094 030 003 070 6 48 337 t2 0009 HOPE 0012 366 4,66 WO" SYSTEM 4304 095 0.29 4060 030 002 OJI 6 46 147 12 0036 HOPE 4012 732 932 J. CDS2 SYSTEM 1406 0,95 141 0195 030 0.06 1A7 8 4.8 7.07 15 0014 HOPE 0012 828 6.75 7-7 -- ,' ,,.. 'Ra'niall rnlensltyprovlded by Connell UniversiVs NRCC Aklas of Pfactpikation Extremes for the Northeastern United Slakes end Southeastern Canada per North Andover Slormwmter Management&Erosion Conlrol Regulations,adopted WISH I. Prepared by. 8ohler Engineedng 45 Franldtn Street,6kh Floor %orlon,MA 02127 (617J 040-8040 W1912024 COW)HNTECH ENGINEERED SOLUTIONS Purpose: To calculate the water quality flow rate (WQF)over a given site area. In this situation the WQF is derived from the first 1"of runoff from the contributing impervious surface. Reference: Massachusetts Dept. of Environmental Protection Wetlands Program/United States Department of Agriculture Natural Resources Conservation Service TR-55 Manual Procedure: Determine unit peak discharge using Figure 1 or 2. Figure 2 is in tabular form so is preferred. Using the tc, read the unit peak discharge (qu)from Figure 1 or Table in Figure 2. qu is expressed in the following units: cfs/mi2lwatershed inches (csmlin). Compute Q Rate using the following equation: Q=(qu) (A) (WQV) where: Q =flow rate associated with first 1"of runoff qu =the unit peak discharge, in csm/in. A= impervious surface drainage area (in square miles) WQV=water quality volume in watershed inches(1"in this case) Structure Impv. A tc t� WQV Name acres miles2 rein hr (in) qu (csmlin.) Q (cfs) 0.0003192 5 0 0.100 'E.t70 774A0 0.0025755 ,6 0 0.100 1�00,, ;' 774.00 0,0001973 ..,.a6;,0 0.100 'I 00 .;', 774.00 _1NQU 2.: ....0.20 0.0003157 ' Ga) 0.100 .1,Qp 774.00 h �i�� � ��111111 C obiw-N T E C H ENGINEI�-JR _P O I LUT,IONS.,' .. CDS ESTIMATED NET ANNUAL SOLIDS LOAD REDUCTION BASED ON THE RATIONAL RAINFALL METHOD 419 & 435 ANDOVER ST NORTH ANDOVER, MA Area 0.20 ac Unit Site Designation CDS-1 Weighted C 0.9 Rainfall Station# 68 t" 6 min CDS Model 1616-3 CDS Treatment Capacity 1.0 cfs Rainfall Percent Rainfall Cumulative Total Flowrate Treated Flowrate Incremental Intensity' Volume Rainfall Volume cfs cfs Removal (%p1 inlhr 0.02 9.3% 9.3% 0.00 0.00 9.1 0.04 9.5% 18.8% 0.01 0.01 9.2 0.06 8.7% 27.5% 0.01 0.01 8.4 0.08 10.1% 37.6% 0.01 0.01 9.7 0.10 7.2% 44.8% 0.02 0.02 6.9 0.12 6.0% 50.8% 0.02 0.02 5.8 0.14 6.3% 57.1% 0.03 0.03 6.0 0.16 5.6% 62.7% 0.03 0.03 6.3 0.18 4.7% 67.4% 0.03 0.03 4.4 0.20 3.6% 71.0% 0,04 0.04 3.4 0.25 8.2% 79.1% 0.05 0.05 7.7 0.50 14.9% 94.0% 0.09 0.09 13.6 0.75 3.2% 97.3% 0.14 0.14 2,8 1.00 1.2% 98.5% 0.18 0.18 1.1 1.50 0.7% 99.2% 0.28 0.28 0.6 2.00 0.8% 100.0% 0.37 0.37 0.6 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 94.4 Removal Efficiency Adjustment2= 6.5% Predicted%Annual Rainfall Treated 93.5% Predicted Net Annual Load Removal Efficiency = 87.9% 1 -Based on 10 years of rainfall data from NCDC station 736, Blue Hill, Norfolk County, MA 2 -Reduction due to use of 60-minute data for a site that has a time of concentration less than 30-minutes. �Ill�� C1v94`;J.wtNTECH`ENGINEERED SOLUTIONS %&gab CDS ESTIMATED NET ANNUAL SOLIDS LOAD REDUCTION BASED ON THE RATIONAL RAINFALL METHOD 419 & 436 ANDOVER ST NORTH ANDOVER, MA Area 1.66 ac Unit Site Designation CDS-2 Weighted C 0.9 Rainfall Station## 68 to 6 min CDS Model 2020-5 CDS Treatment Capacity 2.2 cfs Rainfall percent Rainfall Cumulative Total Plowrate Treated Flowrate Incremental 1 Intensity Volume' Rainfall Volume cfs cfs Removal(°/al 0.02 9.3% 9.3% 0.03 0.03 9.0 0.04 9.5% 18.8% 0.06 0.06 9.0 0.06 8.7% 27.5% 0.09 0.09 8.2 0.08 10.1% 37.6% 0.12 0.12 9.4 0.10 7.2% 44.8% 0.15 0.15 6.6 0.12 6.0% 50.8% 0.18 0.18 5.5 0.14 6.3% 57.1% 0.21 0.21 5.7 0.16 5.6% 62.7% 0.24 0.24 5.0 0.18 4.7% 67.4% 0.27 0.27 4.2 0.20 3.6% 71.0% 0.30 0.30 3.2 0.25 8.2% 79.1% 0.37 0.37 7.0 0.50 14.9% 94.0% 0.74 0.74 11.1 0.75 3,2% 97.3% 1.11 1.11 2.0 1.00 1.2% 98.5% 1.48 1.48 0.6 1.50 0.7% 99.2% 2.23 2.20 0.2 2.00 0.8% 100.0% 2.97 2.20 0.2 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 87.0 Removal EfficiencyAdjustmentz 6.5% Predicted %Annual Rainfall Treated= 93.3% Predicted Net Annual Load Removal Efficiency 80.6% r1 -Based on 10 years of rainfall data from NCDC station 736,.Blue Hill, Norfolk County, MA 2 -Reduction due to use of 60-minute data for a site that has a time of concentration less than 30-minutes. \E/ alk 0PAWNTECH " - ENGINEERED SOLUTIONS �t•�'w«a«� CDS ESTIMATED NET ANNUAL SOLIDS LOAD REDUCTION BASED ON THE RATIONAL RAINFALL METHOD 419 & 435 ANDOVER ST NORTH ANDOVER, MA Area 0.20 ac Unit Site Designation WQU-2 Weighted C 0.9 Rainfall Station# 68 t'� 6 min CDS Model 1515-3 CDS Treatment Capacity 1.0 cfs Rainfall Percent Rainfall Cumulative Total Flowrate Treated Flowrate Incremental Intensity' Volume' Rainfall Volume cfs cfs Removal(%] inlhr 0.02 9.3% 9.3% 0.00 0.00 9.1 0.04 9.5% 18.8% 0.01 0.01 9.2 0.06 8.7% 27.5% 0.01 0.01 8.4 0.08 10.1% 37,6% 0.01 0.01 9.7 0.10 7.2% 44.8% 0.02 0.02 6.9 0.12 6.0% 50.8% 0.02 0,02 5.8 0.14 6.3% 57.1% 0.03 0.03 6.0 0.16 5.6% 62.7% 0.03 0.03 5.3 0.18 4.7% 67A% 0.03 0.03 4.5 0.20 3.6% 71.0% 0.04 0.04 3.4 0.25 8.2% 79.1% 0,05 0.05 7.7 0.50 14.0% 94.0% 0.09 0.09 13.6 0.75 3.2% 97.3% 0.14 0.14 2.8 1.00 1.2% 98.5% 0.18 0.18 1.1 1.50 0.7% 99.2% 0.27 0.27 0.6 2.00 0.8% 100.0% 0.36 0,36 1 0.6 0.00 0.0% 100.0% 0.00 0.00 0,0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.00 100.0% 0.00 0.00 0.0 0,00 0.0% 100.0% 0.00 0.00 0.0 94.4 Removal Efficiency Adjustment2= 6.5% Predicted %Annual Rainfall Treated= 93.5% Predicted Net Annual Load Removal Efficiency $8.0% 1 -Based on 10 years of rainfall data from NCDC station 736, Blue Hill, Norfolk County, MA 2 -Reduction due to use of 60-minute data for a site that has a time of concentration less than 30-minutes. CW411IRNTECH" ENGINEERED SOLUTIONS Nam CDS ESTIMATED NET ANNUAL SOLIDS LOAD REDUCTION BASED ON THE RATIONAL RAINFALL METHOD 419 & 435 ANDOVER ST NORTH ANDOVER, MA Area 0.13 ac Unit Site Designation WQU-1 Weighted C 0.9 Rainfall Station # 68 t� 6 min CDS Model 1516-3 CDS Treatment Capacity 1.0 cfs Rainfall percent Rainfall Cumulative Total Flowrate Treated Flowrate Incremental Intensity' Volume' Rainfall Volume cfs cfs Removal (%) fnlhr 0.02 9.3% 9.3% 0,00 0.00 9.1 0.04 9.5% 18.8% 0.00 0.00 9.2 0.06 8.7% 27.5% 0.01 0.01 8.4 0.08 10.1% 37.6% 0.01 0.01 9.7 0.10 7.2% 44.8% 0.01 0.01 6.9 0.12 6.0% 50.8% 0.01 0.01 5.8 0.14 6.3% 57.1% 0.02 0.02 6.1 0.16 5.6% 62.7% 0.02 0.02 5.4 0.18 4.7%a 67.4% 0.02 0.02 4.5 0.20 3.6% 71.0% 0.02 0.02 3.5 0.25 8.2% 79.1% 0.03 0.03 T8 0.50 14.9% 94.0%© 0.06 0,06 13.9 0.75 3.2% 97.3% 0.09 0.09 2.9 1.00 1.2% 98.5% 0.11 0.11 1.1 1.50 0.7% 99.2% 0.17 0.17 0.6 2.00 0.8% 100.0% 0.23 0.23 0.6 0.00 0.0% 100.0% 0.00 0.00 0.0 0,00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 0.00 0.0% 100.0% 0.00 0.00 0.0 95.5 Removal Efficiency Adjustment2= 6.5% Predicted %Annual Rainfall Treated= 93.5% predicted Net Annual Load Removal Efficiency= 89.0% 1 -Based on 10 years of rainfall data from NCDC station 736, Blue Hill, Norfolk County, MA 2-Reduction due to use of 60-minute data for a site that has a time of concentration less than 30-minutes. Geotechnical Consultants, Inc. (508)229-0900 FAX (508)229-2279 SUBSURFACE INVESTIGATIONS AND FOUNDATION RECOMMENDATIONS 419 & 435 Andover Street North Andover, Massachusetts prepared for Crosspoint Associates,Inc. 188 Needham Street, Suite 255 Newton,MA 02464 GEOTECHNICAL CONSULTANTS,INC. F,I'Cay ' Dooley aniel Kenneally,P.E. GCI Project No. 2204955 3 December 2020 (Rev. 1 - 12/8/20) 201 Boston Post Road West Marlborough, Massachusetts 01752 Geotechnical Consultants, Inc. (508)229-0900 FAX (508)229-2279 3 December 2020 (Rev. I - 12/8/2020) Crosspoint Associates, Inc. 188 Needham Street, Suite 255 Newton, MA 02464 Attention: Mr. Kerry McCormack RE: Subsurface Investigation and Foundation Recommendations 419 &435 Andover Street-North And over,-Massachusetts GCI Project No. 2204955 Dear Mr. McCormack : In accordance with our proposal and your authorization to proceed,we have completed a subsurface investigation and geotechnical evaluation at 419 &435 Andover Street in North Andover, Massachusetts, Presented herein and attached is a summary of the site and subsurface conditions along with recommendations for the design and construction of the foundations and other geotechnical aspects of the currently proposed project. Information used to prepare this report, including existing site features and proposed constructions was obtained in part from the following sources: • Drawing set entitled"Proposed Site Plan Documents",prepared by Bohler, dated 22 October 2020. • Drawing entitled"Conceptual Layout Plan"prepared by Bohler, dated 9 September 2020. • Drawing entitled"Boundary& Topographic Survey",prepared by Control Point Associates,Inc. dated 26 February 2020. Some information regarding the proposed development was obtained from discussions with various members of the project team and staff at Crosspoint Associates,Inc. SITE DESCRIPTION AND PROPOSED CONSTRUCTION Located on the west side of Andover Street in North Andover,Massachusetts,the subject site is an irregularly shaped lot containing approximately 2.691 acres of land over two separate parcels. Surface grades throughout the site slope upward from west to east with elevations ranging from approximately 201±feet to 218-±feet. The general site vicinity 419&435 Andover Street North Andover,Massachusetts 3 December 2020(Rev.1-12/8120) GCI Project No.2204955 Page#2 is shown on the Locus Plan attached as Figure 1. and the aerial Orthophoto Map attached as Figure 2. Two, one-story buildings, are currently located on the site; an Ethan Allen retail store that will be demolished and a Bertucci's restaurant. The Bertucei's restaurant building is designated as Existing Building"C" on the Site Layout Plan dated 22 October 2020. The following is planned for the proposed site development: • The existing Ethan Allen building will be demolished as part of the construction and a new building will be constructed in the eastern half of the existing building footprint. This new building is being referred to as Proposed Building"A" and will have a footprint area of approximately 7,5001 square feet. The finished floor elevations are to be set at 215.30 feet for the proposed urgent care and 214.64 feet for the proposed restaurant. • A new building will be constructed in the western corner of the property. This new building is referred to as Proposed Building "B" and will have a footprint area of approximately 3,352-±square feet. The finished floor elevation is to be set at elevation 208.50 feet. • Existing Building"C" is currently a Bertucci's Restaurant and will remain as-is with no current proposed renovations. The building footprint that currently exists is approximately 6,0301 square feet and has a finished floor elevation set at 214.64 feet. SUBSURFACE INVESTIGATION & CONDITIONS The subsurface investigation included nine (9)test borings made near and within the proposed site development areas. Borings are designated as B-1 through B-9 and completed by Carr-Dee, Corp.,under the supervision of Geotechnical Consultants, Inc. on 16 and 17 November 2020. The boring locations were established in the field using tape survey measurements from existing site features used as reference. Copies of the boring logs are attached and the positions of each exploration are shown on the Location Plan attached as Figure 3. All recently completed boreholes were advanced using hollow stem augers. Soil samples were recovered at each borehole using a standard split spoon sampler driven in accordance with A5TM D-1556. The number of blows required to advance the standard sampler was recorded and the Standard Penetration Number(N-value)was determined. Soil samples were generally recovered at five foot intervals in each borehole. lam/ w 419&435 Andover Street North Andover,Massachmetts 3 December 2020(Rev. 1-12/8/20) GC1 Project No.2204955 Page 93 The soil samples have been placed in storage in our laboratory and we will continue to store the samples for a period of not less than three months. Subsequently,the samples will be discarded unless otherwise directed. Based on the results of the boring program,the general subsurface profile at the site includes: • Suifcial Cover:A layer topsoil or asphalt pavement was encountered at all boring locations ranging in thickness from approximately 6-inches to 12-inches of topsoil or 3-inches to 4-inches of asphalt, • Granular Fill.All boring locations included a layer of fill material consisting of varying proportions of sand, silt and gravel and loam. The fill layer varied in thickness throughout the site from approximately 2 feet to 6 feet beneath the existing surface elevations. • Silty Sand:Medium dense to very dense, silty sand with varying proportions of gravel. This layer was encountered at all boring locations. Groundwater measurements were made upon completion of each borehole through the hollow stem augers. Using the short duration measurements, groundwater was only observed at boring locations 113-6 and B-7 at depths 10±and I5±feet below the existing ground surface. At borehole B-3, a groundwater monitoring well was installed to allow measurements of the stabilized groundwater level. Fluctuations in groundwater levels should be expected and are influenced by seasonal variations,precipitation, site features, nearby construction activities and other environmental factors. ANALYSIS AND RECOMMENDATIONS Based on the results of the subsurface investigation,the proposed building and building additions can be founded on conventional spread footings and the lowest floor slabs can be constructed as a cast-in-place concrete slab-on-grade. In the current state,the fill and its constituents are unsuitable for load support. Although the proposed buildings can be designed and constructed on spread footing foundations, some site preparation will be required. Presented below are the basic design recommendations for footings, slabs-on-grade and paved parking areas, The recommendations assume the site preparation is completed as detailed in the subsequent sections of this report. NO W 419&435 Andover Street North Andover',Massachusetts 3 December 2020(Rev. 1-1218f20) GO Project No.2204955 Page#4 Spread Footing Foundations All new building foundations can be designed and constructed as typical spread footings. Given the expected slab elevations and site grading, it is anticipated the footings will bear on either the Silty Sand stratum, or on compacted structural backfill. Footings can be sized for allowable contact pressure of up to 2 tons per square foot(4,000 psf) for subgrade consisting of either the silty sand or structural backfill. Given the anticipated foundation loads, minimum dimensions of two feet wide for strip footings and three feet square for individual column footings will likely govern regardless of the footing subgrade material. All footings should be placed below the minimum local frost depth. Although not explicitly stated in the current edition of the Massachusetts State Building Code,the local frost depth has historically been prescribed by Code as four feet below finished exterior grade. In our opinion,the historic minimum frost depth should be maintained for this project. Interior footings can bear at the highest level compatible with the floor slab elevation. Ground Floor The lowest level slabs can be designed as cast-in-place concrete slabs-on-grade. The slabs should be supported on a subbase layer of material meeting the gradation limits for imported structural fill. Imported structural fill subbase should be at least 8-inches thick. Imported structural fill for the slab subbase must consist of clean well-graded granular soil or other dense processed aggregate compacted to at least 95%modified Proctor density as determined by ASTM D1557 with gradation limits provided in the Conshwetion Considerations section of this report. Material used for the subbase and as structural backfill must be free of organic material, loam, asphalt, snow, ice, frozen soil and other objectionable material. Prior to construction, a sample of the proposed material should be obtained directly from the source location and tested to assure proper gradation and verify the material is free from oil or hazardous material as defined by the Massachusetts Contingency Plan (MCP). Consider reinforcing the ground floor slab for crack control. Reinforcement and slab thickness can be determined using either the PCA or WRI method with a modulus of subgrade reaction equal to 200 psi/inch, Although vapor barriers may aggravate problems associated with plastic shrinkage and cracking, we recommend placing a vapor barrier directly below the slab in areas which will receive finishes such as coatings, tile or glued carpeting. The vapor barrier should 419&435 Andover Street North Andover,Massachusetts 3 December 2020(Rev. 1-1218120) GCI Project No.2204955 Page#5 consist of a Stego Wrap Vapor Barrier by Stego Industries LLC, or equal,with a Water Vapor Transmission Rate of 0.3 perms or lower per ASTM E 96. Seams should be sealed in accordance with the manufacture's recommendation. Where trenches are required for the placement of the underslab utilities, backfill within the trenches must be adequately compacted to provide continuity of slab support. Trench backfill material should be consistent with the gradation of the slab subbase or as required for the specific utility application. Pavement and Parking Areas Flexible pavement design for standard and heavy duty pavement sections are based on the AASHTO Guide for Design of Pavement Structures. The thickness of each course depends on subgrade strength,traffic, design life, serviceability factors and frost susceptibility. Reference is made to the Commonwealth of Massachusetts Department of Public Works (MADPW) specifications for Bridge and Highway construction, 1988 edition. In all paved areas, the subgrade should be heavily proofrolled using at least eight passes of a 20-ton vibratory roller operating at maximum amplitude. Where the fill is required to attain the desired grade, the ordinary fill should consist of predominately clean granular soil with no heavy concentration of decayable matter or other deleterious material. The fill should be placed in lifts not exceeding 12 inches loose measure and should be compacted to at least 92%modified Proctor density. Adequate precautions to protect the subgrade, as described above,must be implemented. The following materials should be used to construct the pavement sections: Thickness inches Pavement Material Standard Du Heavy Duty Bituminous Concrete Top Course, 1.0 1.0 MA DPW M3.11.03 Table A Bituminous Concrete Binder Course, 2.0 3.0 MA DPW M3.11.03 Table A Processed Gravel for Subbase Course 8.0 12.0 MA DPW M1.03.1 The Processed Gravel must consist of inert material that is hard, durable stone and coarse sand,free from loam and clay, surface coatings and other deleterious materials..The coarse aggregate should have a percentage of wear of not more than 50 when tested by �W 419&435 Andover Street North Andover,Massachusetts 3 December 2020(Rev.1-12/8/20) GCI Protect No.2204955 Page##6 the LA Abrasion Test. Gradation limits for Processed Gravel subbase course must meet the following requirements: Sieve Size Percent Passim 31 1 100 '.. l%" 70-100 50-85 No. 4 30-60 No. 200 0-10 Subbase course must be compacted to at least 95 percent of the maximum dry density as determined by the Proctor Test(AASHTO T-99). Bituminous concrete must be placed at the specified temperature range and compacted to at least 95 percent of the Marshall Density for the job mix formula. It is recommended that the standard duty section, as provided above, be constructed in parking and lightly traveled areas. The heavy duty pavement section should be constructed at primary drives,delivery areas, and other areas subjected to heavy car or truck traffic, Positive site drainage must be provided in all paved areas, Drive-up Area Pavement Both proposed building"A" and "B"will consist of a paved drive-thru that will be constructed to service the proposed restaurant and bank. We recommend the drive-up area be paved with Portland Cement Concrete Pavement(PCCP), Minimum Concrete Thickness: 7-inches The specified concrete mix should include; Minimum Strength: 4000 psi @ 28 days Nominal Coarse Aggregate Size: 1-inch Minimum Cement Content: 564 lbs.per cubic yard Maximum Water Cement Ratio: 0.45 Maximum Slump at Placement: flinches Minimum Air Content: 6%±1% 419&435 Andover Street North Andover,Massachusetts 3 December 2020(Rev.3-1218/20) GO Project No.2204955 Page#7 The PCCP slab should be reinforced for crack control and the pavement edges should be chamferred. 1n order to protect the slab from frost action, the slab should be directly supported on a gravel subbase layer compacted to at least 95%of standard Proctor density consisting of the following: Processed Gravel for Subbase 12-inches MA DPW M1.03.1 Air entrainment increases the resistance of concrete to disintegration when exposed to freezing and thawing, increases resistance to scaling(surface disintegration)that results from deicing chemicals, increases resistance to sulfate attack, and reduces permeability. However, air entrainment agents affect the workability of the concrete during placement. As a cautionary note, scaling and delaminating of the wearing surface of air entrained concrete slabs can occur if"over-troweled"at the time of finishing. Consider using a concrete mix containing pozzolan. Pozzolanie materials are materials comprised of amorphous siliceous or siliceous and aluminous material in a finely divided (powdery)form, similar in size to Portland cement particles,that will,in the presence of water,react with an activator,typically calcium hydroxide and alkalis,to form compounds possessing cementitious properties. Descriptions of various kinds of pozzolans and their specifications are provided in ASTM C618, Seismic Considerations Earthquake loadings must be considered with respect to the requirements of Section 1613 of the Massachusetts State Building Code. In addition,the liquefaction potential of the underlying soils must be evaluated in accordance with Section 1806.4 of the Massachusetts Code Amendments. Site classifications are based on the average density, and hence the ability of the soil to transmit shear waves during a seismic event. The average density is based on the material, both soil and rock,within 100 feet below the building. The site classification is then used to determine the site coefficient and mapped spectral response for a given structure. The applicable seismic design criteria are as follows: PF �J I 419&435 Andover Street North Andover,Massachusetts 3 December 2020(Rev. 1-12/8/20) GC1 Project No.2204955 Page##8 Site Class D: Stiff soil profile. Spectral Response Acceleration at short period, SS(Table 1604.11): 0.251g Spectral Response Acceleration at 1 sec., S1 (Table 1604.11): 0.076g Site Coefficient,Fa(Table 1613.5.3(1)): 1.6 Site Coefficient,F„(Table 161.3.5.3(2)): 2.4 Adjusted spectral response, Stfs(Equation 16-36): 0.402g Adjusted spectral response, S., (Equation 16-37): 0.182g Based on the result of the borings and in accordance with the provisions of the Code,the soils at the site are not considered susceptible to liquefaction. CONSTRUCTION CONSIDERATIONS The primary purpose of this section of the report is to comment on items related to excavation,foundation construction, site preparation and related geotechnical aspects of the proposed construction. It is written for the Architect and Engineer having the responsibility for the preparation of plans and specifications. Since it identifies potential construction problems related to foundations and earthwork, it will also aid personnel who monitor construction activities. Prospective contractors for this project must evaluate construction problems on the basis of their own knowledge and experience in the area, and on the basis of similar projects in other localities,taking into account their proposed construction procedures. Excavation,Handling and Disposal of Fill Soils The construction documents should include provisions for soil management and require the Contractor to develop, implement, and supervise a Worker Health and Safety Program. The construction phase-specific plan, should incorporate, at a minimum, a general Health and Safety Program to limit safety-related accidents and to promote health in the construction workplace. The Program should include provisions which will limit exposures of workers to contaminants through ingestion,dermal contact and inhalation. The soil management plan must be developed in cooperation with the project environmental consultant. The contents of the soil management plan will depend upon the nature and character of the fill soils. Disposal and recycling of all classified soils from excavation activities must be performed in general conformance with applicable Federal, State and Local regulations governing Oils and Hazardous Materials (OHMs). Site Preparation Site preparation within the proposed building footprints will include: stripping of the asphalt/topsoil and removal of varying quantities of fill. Any existing below grade foundation remnants and existing underground utilities will require demolition and removal from the site and should be replaced with structural backfill. 419&435 Andover Street North Andover,Massachusetts 3 December 2020(Rev.1-12/8/20) GO Project No.2204955 Page 49 Within the proposed building footprints of the Existing Buildings"A" and "B", all previously placed fill must be completely removed. Based on the boring information, excavation depths will range from about 2':-k to 6':L feet below existing grade with the potential for locally deeper excavation to ensure the complete removal of the fill. Loam and topsoil may be stockpiled and reused in landscaped areas provided it meets the specified requirements for plantings. Excavated material that are predominantly granular and able to be compacted into a stable mass,may be re-used as back:611. During the excavation and stockpiling of the on- site fill, all decayable or deleterious matter should be culled from the stockpile and legally disposed of off-site. Additionally, if necessary, the on-site soils may be blended with coarse aggregate to produce a well-graded mixture suitable for placement as structural backfill. After removing the surficial cover and previously placed fill, it is recommended the exposed subgrade be heavily proof compacted using a vibratory drum roller having a minimum drum width of at least eight feet and a rated dynamic weight of at least 20 tons. In order to maximize the vibratory densification process,proof-rolling should be performed with the roller operating at maximum amplitude. .Each roller pass should be made in perpendicular directions to one another to ensure full coverage. Should"weak"spots be encountered during the proof rolling operation,they should be investigated by excavating test pits to identify the specific, localized conditions. Unsuitable materials, including organic soils, deleterious or decayable materials,must be removed. Where over excavation is required to remove unsuitable materials, all backfill must be placed as structural backfill as defined below. Imnorted material used for structural backfill should consist of clean well-graded granular soil or other dense processed aggregate with gradation limits as follows and have no stones Iarger than 3" (three inches): Sieve Size Percent Passing 3" 100 %2" 50-85 No. 4 40-75 No. 50 8-28 No. 200 0-8 NO I 419&435 Andover Street North Andover,Massachusetts 3 December 2020(Rev. 1-12/8/20) GC1 Project No.22049SS Page#10 The material used as structural backfill must be free of organic material, loam, snow, ice, frozen soil and other objectionable material. All structural fill, should be placed in 12- inch loose lifts and compacted to a modified Proctor density of 95 percent(ASTM D1557). Prior to construction, a sample of the proposed structural fill material should be obtained directly from the source location and tested to assure proper gradation and verify the material is free from oil or hazardous material as defined by the Massachusetts Contingency Plan (MCP). Excavation for footings and exposed subgrade should be inspected by a qualified geotechnical engineer to ensure adequacy of the subgrade soils. The placement of all structural backfill must be inspected and certified as to its adequacy in compliance with the Massachusetts State Building Code. Backfill sail placed outside the building footprint in areas of non-Ioad support may be "ordinary fill". Ordinary fill should consist of granular soil containing no decayable matter such as roots,wood, organic soil, etc. Ordinary fill should be placed in layers and compacted with available construction equipment to reduce future settlement. Subgrade Maintenance and Protection Based on the groundwater measurements, it is not anticipated general site dewatering will be needed during site preparation or foundation construction. However, the silty sand soils contain portions of fine-grained soils, silt, and may be water sensitive and moderately frost susceptible. Should the fine-grained soils become saturated from run-off,the material loses substantial strength and is difficult to work with and may require removal and replacement with structural backfill. In addition,the fine-grained fractions within the matrix make these soils moderately susceptible to freezing. It is imperative that all exposed subgrade soils be protected from water and prolonged exposure to freezing temperatures. Although groundwater is not anticipated,,dewatering may be required during construction due to precipitation and runoff. Adequate site drainage must be provided to preclude the accumulation of surface water within the building footprint areas as well as the paved parking lot and access roadway. Drainage or dewatering, where needed, must be done so that all work can proceed in-the-dry. Construction Monitoring We recommend that you retain Geotechnical Consultants, Inc, to prepare relevant earthwork, dewatering, and support of excavation specifications and to review your foundation and construction plans for compliance with our geotechnical recommendations. We recommend that Geotechnical Consultants, Inc. also be retained to provide construction observation services during construction to prepare reports in order to satisfy the Massachusetts State Building Code's Special Inspections Reporting requirements (refer to Chapter 17). We strongly recommend that Geotechnical NN 419&435 Andover Street North Andover,Massachusetts 3 December 2020 (.Rev. 1-12!$I20) GCx Project No.2204955 Page#11 Consultants, Inc. be retained to observe and document the following key geotechnical components of construction: • Site preparation including removal of unsuitable materials from beneath building and pavement areas; • Placement and compaction of fill materials; • Final preparation of foundation and slab subgrades; • Placement of all concrete; and • Erection of structural steel. Our involvement during construction will allow evaluation of actual conditions exposed during excavation, and to allow a prompt response should unanticipated conditions be encountered. Our involvement will also efficiently facilitate the field-assessment of areas where partial over excavation of existing soils may be warranted,thereby saving the Owner time and money. NO 1 419&435 Andover Street North Andover,Massachusetts 3 December 2020(Rev.1-1218120) GO Project No.2204955 Page##12 LIMITATIONS This report has been prepared for specific application to 419 &435 Andover Street in North Andover,Massachusetts in accordance with generally accepted geotechnical engineering practices. Conclusions and recommendations made in this report are based upon data obtained from widely spaced subsurface explorations. The nature and extent of variations between these explorations may not become evident until further explorations are conducted or during construction. If significant variations appear, it will be necessary to re-evaluate the recommendations presented in this report. We request that we be provided the opportunity for a general review of the applicable contract drawings and specifications,to determine that our recommendations have been interpreted and implemented as they were intended, If any changes in the nature, design or location of the proposed building is made,we should review the applicability of our recommendations. Sincerely, GEOTECHNICAL CONSULTANTS,INC. r a , Kayla Dooley'° Daniel Kenneally,P.E. DRAW Encls. IM ■ Z"�?r v,y rCTPw}' y Pit ai t t �� '1➢,�^� '� I. '� 's ,r"M ' �;i ' R 1 �� arc Y'� -' >r'��,-NY 7�, --t '"_ :�y�-_�����eVf�A�� ✓���_f rr�iu�� RMy 0A MNOl rPT�10w `-x a ,.r6 4 hr E o'r C r� t ,� htl }g� , ss.rj� x - ?'err' �t h f ■ ­g fir Y RR r"� {� �!'� ,r^ r f�Tr�l a .�.� +y �yai• .mast_ t{ t+. t+i � ^•" �i�� ���v�dr ��!�'#',"t'i��.A�� tt '`r��y �-r.}!I � S��. li "� ! '�� , >r� pI 1��j`��Y �Pu �, Ct J t,A i ¢ f ��"£ la }4l ►+ ��, �� ' .s .��` a... T rah} i3 ,ca Rc s - px7 + lw,y ? 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Color 4rthophoto Map Geotechnical Consultants, Inc. 201 Boston Post Road West Marlborough,MA 01752 (508)229-0900 FAX (508)229-2279 LEGEND 9k _ L, BON PFAFOR EE)BlS CAAR OF DEE '��' '� _ •� "s-- s _.F, r� 0IIOER THE SUPERVISIdN.OF S��m CEd TICE NICiU.'CON 120 0. p1T5,INC.ON Ib >- r. � �. �,• - h 17!.'OYEu9CR 2020. - __ _•�„ gY•-�-.�•— `�' - - _�•„-�+x. 90.5E PLAN TAKER FROM AN ELECTRONIC $ C COPY of A BMW()FMMU 'SRE J4 y — IAYOUf P. PF1tYAREO BY DONFYR, 3$OATE612C10BER 20 20. I'—�..7 L�. � � .,�-d _ u-a •- f ;v� �'�'�= �J f� o,:.:i T, y�;— 3 c7 K� sec " f Z �.• �;��l '��" -.ice-R-� �� � a�. .�./t�,y• `�.I:�I,�..6-' r'r ,mot' / ,s�".�F;� 2 / / c z CARR-DEE CORP. 37 LINDEN STREET MEDFORD, MA 02155-0001 Telephone (781) 391-4500 To: GEOTECHNICAL CONSULTANTS, INC. , MARLBOROUGH, MA. Date: 11-16-2020 Job No. : 2020--149 Location: 419 & 435 ANDOVER STREET, NORTH .ANDOVER, MA Scale: 1 in.= 3 ft. BORING I GROUND SURFACE 801, 0' to 2' (12-7-7-13) RECOVERED 12 in. SN2, 2' to 41 (3-2-2-2) RECOVERED 16 in. SAND, SILT, GRAVEL (PILL) 5113, 4' to 61 RECOVERED 1 in. 6' Si14, 6' to 8' RECOVERED 14 in. COMPACT SILT)( SAND, SOME GRAVEL S05, 20, to 12, (B-13-15W15) RECOVERED 24 in. 12'6" VERY DENSE SILTY SAND 6 GRAVEL 896, 15' to 17' (21-40-30-25) RECOVERED 20 in. 171 NO WATER ENCOUNTERED SIZE OF AUGERS: 2-1/41, I.D., LENGTH: 151011 DRILLER: S. DESIMONE, JR., INSPECTOR: X. DOOLEY DATE STARTED K COMPLETED: 11-16-2020 e Ali samples have been visually classified by.Unless otherwiso specified,water levels noted were observed at completion of borings,and do not necessarily represent permanent ground water levels. Figures in parenthesis indicate tha number of blows required to drive Two-hich Split Sampler 6 inches using 140 lb,weight failing 30 inches(t). Figures in column to left(if noted)indicato number ofblows to drive casing one foot,using 300 lb-weight falling 24 inches(t). Sheet 1 of 1 CARR-DEE CORP. 37 LINDEN STREET INEDFORD, MA 02155-0001 Telephone (781) 391-4500 To: GEOTECHNICAL CONSULTANTS, INC. , MARLBOROUGH, MA Date: 11-18-2020 Job No. : 2020-149 Location: 419 & 435 ANDOVER STREET, NORTH ANDOVER, MA Scale: 1 in.= 3 ft. BORING 2 GROUND SURFACE 3u ASPHALT Sol, 611 to 2161, (3-5-4-5) RECOVERED 12 in. SAND, SILT, GRAVEL (FILL) S02, 21611 to 4161, (5�7�11-12) RECOVERED 12 in. 51 S43, 51 to 7' RECOVERED 18 in. COMPACT SILTY SAND, SOME GRAVEL 9' S114, 101 to 121 (6-7-9-10) RECOVERED 24 in. COMPACT TO DENSE SILT, SAND & ' GRAVEL S115, 151 to 171 (7-16-34-20) RECOVERED 20 in. 171 NO WATER ENCOUNTERED SIZE OF AUGERS: 2-1f411 I.D., LENGTH: 15,01, DRILLER: S. DESIMONE, JR., INSPECTOR: K. DOOLEY - DATE STARTED & COMPLETED: 11-16-2020 All samples have been visually classified by,Unless otherwise specified,water levels noted were observed at completion o€borings,and do not necessarily representylermanent groarud water levels. rigures in parenthesis indicate the number of blows required to drive Two-inch Split Sampler 6 inches using 140 lb.weight falling 30 inches(). Figures in column to left (if noted)indicate number of blows to drive casing one foot,using 300 lb.weight falling 24 inches(t). Sheet I of 1 CARR-DEE CORP. 37 LINDEN STREET MEDVORD, MA 02155-0001 Telephone (781) 391-4500 To: GEOTECHNICAL CONSULTANTS, INC. , MARLBOROUGH, MA Date: 11-18-2020 Job No. : 2020-149 Location: 419 & 435 ANDOVER STREET, NORTH ANDOVER, MA Scale: 1 in.= 3 ft. GROUND BORING 3(OW) SURFACE '.. LOAM (TOPSOIL) y :k 1' Stl1, 1' to 21611 SAND, SILT, GRAVEL (FILL) RECOVERED 16 in. 2`61- S01A, 216" to 3' (11) RECOVERED 6 in. M, 3' to '5 (4-8-13-38) RECOVERED 6 in. COMPACT SILTY SAND & GRAVEL S$3, 5' to 7' (13-18-5-5} RECOVERED 12 in. 7' SIZE OF AUGERS: 3-3/41, I.D., LENGTH: 71011 BRILLPR: S. =SIHONE, JR., INSPECTOR: K. DOOLEY . BATE STARTED & COMPLETED: 11-16-2020 All samples have been visually classified by.i3rdess otherwise specified,water levels noted were observed at completion o£borings,and do not necessarily represent permanent ground water levels. Figures in parenthesis indicate the mnnber of blows required to drive T`wo-inch Split Sampler 6€nohes using 140 lb,weightfidling 30 inches(±). Figums in column to left (if noted)indicate number of�biows to drive casing one foot,using 300 lb,weight falling 24 inches(±). Sheet 1 of 1 CARR-DEE CORP. 37 LINDEN STREET MEDFORD, MA 02155-0001 Telephone (781) 391-4500 To: GEOTECHNICAL CONSULTANTS, INC. , MARLSOROUGH, MA Data, 11-18-2020 Job No. : 2020-149 Location: 419 & 435 ANDOVER STREET, NORTH ANDOVER, MA Scale: 1 in.= 3 ft. GROUND BORING 4 SURFACE 4„ ASPHALT S01, 6" to 216" (4-6-7-7) RECOVERED 14 in, S#2, 2'6" to 416" (3-2-3-27) SAND, SILT, GRAVEL (VILL) RECOVERED 12 in. S#3, 5' to 61 (4-2) RECOVERED 0 in. 6' S03A, 6' to 7' (8-9) RECOVERED 8 in. S#4, 10' to 12' (12-14-16-17) RECOVERED 24 in. COMPACT TO DENSE SILTY SAND & GRAVEL 805, 15' to 17' (11-17-21-22) RECOVERED 16 in. 17' NO WATER ENCOUNTERED SIZE OF AUGERS: 2-1/4" I,D., LENGTH: 710" DRILLER: S. DESIMONE, JR., INSPECTOR: K. DOOLEY - DATE STARTED & COMPLETED: 11-16-2020 All samples have been visually classified by.Unless otherwise spetifiied,water levels noted Nvero observed at completion of borings,and do not necessarily represent pennanent ground water levels.Figures in parenthesis indicate the number of plows required to drive Two-inch Split Sampler 6 inches using 140 lb.weight falling 30 inches(t). Figures in column to left (if noted)indicate number of blows to drive casing one foot,using 300 lb,weight falling 24 inches(L), Sheet 1 of 1 CARR-DEE CORP. 37 LINDEN STREET MEDFORD, MA 02155-0001 Telephone (781) 391--4500 To: GEOTECHNICAL CONSULTANTS, INC. , MARLBOROUGH, MA Date: 11-18-2020 ,Tob No. : 2020-149 Location: 419 & 435 ,ANDOVER STREET, NORTH ANDOVER, MA Scale: 1 in.= 3 ft. GROUND BORING 5 SURFACE Sol, 0' to 2' (2-5-4-8) RECOVERED 12 in. SAND, SILT, GRAVEL (FILL)21 '. 02, 21 to 41 (15-13-14-10) RECOVERED 18 in. COMPACT SAND, SOME SILT, TRACE GRAVES, 5. S#3, 51 to 71 (9-H-11-11} RECOVERED 24 in. COMPACT TO DENSE SILTY SAND, SOME GRAVEL S#4, 10 to 12, (12-18-31-27) RECOVERED 24 in. ,, 15' S#5, 15' to 17' (9-24-29-25) RECOVERED 24 in. VERY DENSE SILT, SAND & GRAVEL 171 NO WATER ENCOUNTERED SIZE OF AUGERS: 2-1/4" I.D., LENGTH: 71011 DRILLER: S. DESIMONE, OR., INSPECTOR: K. DOOLEY DATE STARTED & COMPLETED: 11-16-2020 '.. All samples have been visually classified by.Unless otherwise specified,water levels noted were observed at completion ofborings,and do not necessarily represent permanent ground water levels. Figures in parenthesis indicate the number o£blows reRaired to drive 1\vo-inch 5plil Sampler 6 inches using 14D lb:weiStit falling 30 inches(±), Figures in column to left (if noted)indicate number of blows to drive casing one foot,using 300 lb.weight Falling 2d inches(±). Sheet 1 of 1 CARR-DEE CORP. 37 LINDEN STREET MEDFORD, MA. 02155--0001 Telephone (781) 391-4500 To: GEOTECHNICAL CONSULTANTS, INC. , MARLBOROUGH, MA. Date: 11--18--2020 Job No. : 2020--149 Location: 419 & 435 ANDOVER STREET, NORTH ANDOVER, MA Scale: 1 in.= 3 ft. BORING 6 GROUND SURFACE LOAM (TOPSOIL) S#1, 0' to 6" 6" (2) RECOVERED 6 in. SAND, SILT, AVEL (VILL) S#1A, 6" to GR (2-2-3) RECOVERED 6 in. 2' 02, 2' to A' - (15-18-24-20) RECOVERED 16 in. 8#3, 5' to 7' (7-14-29-21) RECOVERED 12 in. DENSE TO VERY DENSE SILTY SAND & GRAVEL 8#4, 10, to 11, (14-92-100/011) RECOVERED 10 in. S#5, 15' to 16-5" (24-60-100/111) RECOVERED 12 in. 16'1" WATER LEVEL 10' SIZE OF AUGERS: 3-1/4" S.D., LENGTH: 1510" DRILLER: S. DESIMONE, 7R., INSPECTOR; K. DOOLEY DATE STARTED & COMPLETED: 11-17-2020 All samples have been visually classified by.Unless olherwiso specified,water levels noted ware observed at completion o£[zorings,and do not necessarily represent permanent groundwater levels. Figures in parenthesis indicate the number o£biows required to drive Two-inch Split Sampler 6 inches using 140 lb.weiglit falling 30 inches(±). Figures in column to left (if noted)indicate number of blows to drive casing one foot,using 300 lb.weight falling 24 inches(t). Sheet 1 of 1 CARR-DEE CORP. 37 LINDEN STREET MEDFORD, MA 02155-0001 Telephone (781) 391-4500 To: GEOTECHNICAI, CONSULTANTS, INC. , MARLBOROUGH, MA Date: 11-18--2020 .lob No. : 2020-149 Location: 419 & 435 ANDOVER STREET, NORTH ANDOVERt MA Scale: 1 in.= 3 ft. BORING 7 GROUND SURFACE 3„ ASPHALT _ Sol, 611 to 2161, (4-5-6-6) RECOVERED 12 in. SAND, SILT, GRAVEL (WILL) S92, 2161, to 41611 (2-1-2-2) RECOVERED 10 in. 5' S#3, 51 to 71 RECOVERED 20 in. COMPACT SILTY SAND, SOME GRAVEL 814, 10' to 12' RECOVERED 16 in. i i 15' SNS, 151 to 171 RECOVERED 20 in, COMPACT SILT, SAND & GRAVEL 171 WATER LEVEL 15' SIZE OY AUGERS: 2-1/41, I.D., LENGTH; 1510" - DRILLER: S. DESIMONE, JR., INSPECTOR: K. DOOLEY DATE STARTED G COMPLETED: 11-17-2020 All samples have been visually classified by,Unless otherwise specified;water levels noted were observed at completion of borings,and do not necessarily represent pennanent ground water levels. Figures in parenthesis indicate the number of blows required to drive Two-inch Split Sunpler 6 inches using 1401b,weight falling 30 inches(±). Figures in column to left (if noted)indicate number of blows to drive casing one fool,using 300 lb.weight falling 24 inches(t). Sheet 1 of 1 CAR.R-DEE CORP. 37 LINDEN STREET MEDFORD, MA 02155-0001 Telephone (781) 391-4500 To: GEOTECHNICAL CONSULTANTS, INC. , MARLBOROUGH, MA Date: 11-18--2020 Job No. : 2020-149 Location: 419 & 435 ANDOVER STREET, NORTH ANDOVER, MA. Scale: 1 in.m 3 ft. BORING 8 GROUND SURFACE 4„ ASPHALT S1ll, 6" to 2161, (2-2-3-2) RECOVERED 16 in. SAND, SILT, GRAVEL (FILL) 302, 21611 to 4161, (1-2-2-3) RECOVERED 12 in. 5° SYS, 51 to 71 (7-8-11-9) RECOVERED 16 in. COMPACT SILTY SAND, SOM GRAVEL 9, S#4, '101 to 121 (5-6-7-8) RECOVERED 24 in. COMPACT SILT, SAND tv GRAVEL SYS, 15' to 17' (6-7-16-17) RECOVERED 20 in. 17t NO WATER ENCOUNTERED SIZE OF AUGERS: 2-1/4° I.D., LENGTH: 1510" DRILLER: S. DESIMONE, OR., INSPECTOR: K. DOOLEY DATE STARTED & COMPLETED: 11-17-2020 All samples have been visually classified by.Unless otherwise specifed,water levels noted were observed at completion of borings,and do not necessarily representperntanent grormd water levels. Figures in parenthesis indicate the number of blows required to drive Two-inch Split Sampler 6 inches using 140lb.weight falling 30 inches(±). Figures in cohrmn to left (ifnoted)indicate number ofblows to drive casing one foot,using 3001b.weight falling 24 inches(±). Sheet 1 of 1 ,i CARR-DEE CORP. 37 LINDEN STREET MEDFORD, MA 02155-0001 Telephone (781) 391--4500 To: GEOTECHNICAL CONSULTANTS, INC. , MARLBOROUGH, MA Date: 11--18-2020 Job No. : 2020--149 Location: 419 & 435 ANDOVER STREET, NORTH ANDOVER, MA Scale: 1 in.= 3 ft. BORING 9 GROUND '. SURFACE '.. 4„ ASPHALT S$1, 6" to 21611 (2-3-6-10) SAND, SILT, GRAVEL (FILL) RECOVERED 20 in. 216o 502, 21611 to 416" {13-15M17-16y RECOVERED 20 in. S03, 51 to 71 {14-51-15-16) 'RECOVERED 20 1n. DENSE TO VERY DENSE SILTY SAND, SOME GRAVEL SO4, 10 to 121 (15-17-16-21) RECOVERED 20 in, 14, S05, 15' to 17' COMPACT SILT, SAND & GRAVEL (10-10-11-13) RECOVERED 20 in. 17, NO WATER ENCOUNTERED SIZE OF AUGERS: 2-1/41, S.D., LENGTH: 1510" - DRILLER: S. DESINIONE, JR_ INSPECTOR: K. DOOLEY DATE STARTED 6 COMPLETED: 11-17-2020 All samples have been visually classified by.Unless otherwise specified,water levels noted were observed at completion of borings,and do not necessarily represent permanent ground water levels. figures in parenthesis indicate the number of blows required to drive Two-inch Split Sampler 6 inches using 1401b,weight falling 30 inches(±). Figures in column to left (if noted)indicate number of blows to drive casing Due foot,using 300 lb.weight falling 24 inches(�). Sheet 1 of 1 45 Franklin Street, 5th Floor BOHLER # Boston, MA 02110 617.849.8040 December 21, 2020 North Andover Planning Department 120 Main Street North Andover, MA 01845 Attn: Jean Enright, Planning Director Qenright@northandoverma.gov) Re: Response to Comments for Stormwater Peer Review Letter 419 &435 Andover Street North Andover, MA Dear Ms. Enright, On behalf of the applicant, Crosspoint Associates, Inc., below please find our responses to the Initial Stormwater Peer Review Letter from Horsley Witten Group dated 12/17/20, Included in support of these responses are the following materials: • One (1)copy of the Site Development Plans, prepared by Bolder, dated October 22,2020, revised December 21, 2020; • One (1) copy of the Pipe Sizing Calculations, prepared by Boher, dated November 17, 2020, revised December 21, 2020. For clarity,the original comments are in a bold font type with numbering consistent with the review letter, while Bohler's responses are directly below in an italicized font type. Responses are provided only for comments that warrant a response. Comments: 2. a. The Applicant has revised its proposed HydroCAD and renamed AD-4 to C13-11 on the plans (Sheet C-401). The outfalls appear to still pond in areas of WQU-2, C113-10, and CB-11 as noted in the Applicant's response.A designed overflow has been added at C13-11 with r%prap. HW recommends that the Applicant add spot grades behind the curb at WQU-2 to ensure ponding will not occur behind the curb in this area. Response to Comment: Additional spot grades have been added behind the curb at WQU-2 as recommended. 11. The Applicant has provided a rational pipe sizing calculation table. It appears to be incomplete.The table provides calculations for the main line and water quality or proprietary structures only. HW recommends that the Applicant Include the following in the table: •All routing of pipes from all catch basinslinlets to the stormwater system. -Inverts of pipe to confirm slope(also to confirm slope of pipe on plans) • Lengths of pipe to confirm slope (also to confirm slope of pipe on plans) www.BohEerBn91 neering.aom BOHLER // Response to Comment: Limited pipe sizing was provided previously to show the critical pipe runs were sized properly, and, as a result, that upstream pipe runs were suitably sized, based on their smaller contributing areas. The applicant has provided the remaining requested pipe sizing in the revised table, as well as the additional requested information and labels. We trust the above is sufficient for your needs at this time. Should you have any questions or require additional information, please do not hesitate to contact us at(617)849-BO40. Sincerely, BOHLER ENGINEERING Zachary L. Richards, P.E. Stephen Martorano, P.E, www.BohlerEngineering.com S I Deslgn.Period Storm. 10'i Year ....:::Design Par!o: LOCATION 11VIPPRVIOU8 FROM TO A C CA A Ps) WQU-1 SYSTEM 0,127 0.95 0,12 0.0 W6U-2 SYSTEM 0.205 0.95 0.19 0:4' CB-11 ' SYSTEM 0,000 0.95 0.00 0.1P CB-5 CD3-1.,. 0.202 0.96 0,19 0.0 CDS-1 SYSTEM 0.202 0.95 0.19 0.0 CB-1 DMH-1 0.640 0.95 0.04 0.0 CB-2 DMH-1 0.148 0.95 0.14 0.0 C13 3 DMH-.1., . :0.033 0.96 .0.03 0.0 RD-1 DMH-1 0.122 0.95 0.12 0.0 Ab-1 PIPE 0.061 0.95 ' 0.06 0.0 bMH-1 DMH-2 0.404 0.95 0.38 0.0 A6-2 PIPE 0,000 0.95 0.00 0.0 RD-2 DMH-2 0.056 0.95 0.05 0.0 GB-4 DMH-2 0.120 0.95 0.11 0.0 DMH-2 DMH-4 0,580 0.95 0.55 0.0- CB-6 DMH 3 0,380 0.95 0.36 0.01 J. C6-8 DMH-3 0.210 0.95 0,20 0.0 CB 9 DMH-3 0A 13 0.95' 0 11 0.0 DMH-3 DMH-4 0.703 0,95` 0.67 0.1 CB-7 DMH-4 0,105 0.95 0.10 0.0 DMH 4 CDS-2 1.388 0.95 1.32 0.1 RD 3 CDS-2 0,076 0.95 0.07 0.0 CB-10 CDS 21 0.080 0.95 0,08 off CDS 2 SYSTEM 1.544 0 95 1.47 0.2 'Rainfall Intensity provided by Cornell University's NRCC Atlas of P11. Prepared by: Bohler Engineering 45 Franklin Street,5th Floor Boston,MA 02127 (617)849-8040 12/21/2020