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HomeMy WebLinkAbout2022-04-26 Stormwater Review WSP Horsley W*itten Group , Sustainable Environmental Solutions 112 Water Street-6 Floor*Boston,MA O2109 1 March 24, 2022 Ms,. dean Enright, Planning Director Planning Department Town of North Andover 120 Main Street North Andover, Massachusetts 01845 Rey Initial Stormwater Peer Review 198 Dale Street North Andover, Massachusetts Deer 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 Storm water Management Report and Site Plan for the proposed improvements to 198 Dale Street in North Andover, MA. The plans were prepared by Ranger Engineering Group, Inc. for Paul and Heather Tol esien (Applicant). The project proposes the construction of o 960 square foot sf two-story garage in the non- discharge zone and a small area of grading in the non-disturbance zone on a 0.9 acre parcel. The storm water management for the proposed improvements includes ,a subsurface infiltration system consisting of concrete galleys and crushed stone. A total of 6610 square feet sf of additional impervious area is proposed on site. The property is located within the watershed Protection District and the house was built in 1956. In ,accordance with §195-4.18F of the North Andover Zoning Bylaws, the 325-foot. Non-Discharge ,done and the 1 Cog-foot Non-Disturbance 'one from the wetland area located onsite applies to the site. Any surface or subsurface discharge proposed within the Non-Discharge Buffer Zone requires a Special Watershed! Permit.. The following documents and plans were received by HW Special Permit-'watershed Permit Application, 1918 Dale Street, North Andover, Massachusetts, prepared by Ranger Engineering Group, Inc, dated March g, 0 7 pages); -Stoirm eater-Management Report, 198 Dale Street North Andover, Massachusetts, prepared by Ranger Engineering Group, Inc, dated March 9, 2022 94 pages), and Site Plan for 198 Dale Street, North Andover, Massachusetts, prepared by Ranger Engineering Group, Inc, dated March g, 2022 1 sheet),. Town of North Andover March 24, 2022 Page 2 of 3 Stormwater Management Design Peer Review In accordance with §195-4.19. B. (4)All construction in the watershed Protection District shall comply with best management practices for erosion, siltation, and stormwater control in order to preserve the purity of the groundwater and the lake; to maintain the groundwater table; and to maintain the filtration and purification functions of the land. HW has the following comments regarding the proposed stormwater management design. 1. The Applicant intends to expand its driveway and construct a 24 foot by 40 foot garage. The driveway runoff will be captured by a catch basin. Runoff from the catch basin will be piped to a subsurface galley system. The subsurface system includes eight (8) 4 foot by 4 foot concrete galley chambers that will be surrounded by crushed stone. The roof runoff from the new garage and a portion of the existing house will also be piped to the subsurface galley system. The proposed galley system has an outlet pipe that discharges north towards the onsite wetland. The discharge point is approximately 100 feet from the wetland and outside of the 100-foot non-disturbance zone. 2. currently the chamber outlet tee is set at elevation 96.5 and the inlet from the catch basin is proposed at elevation 95.5. HW recommends that the Applicant raise the inlet pipe as high as feasible in the catch basin and therefore higher in the chambers to minimize stormwater from backing up into the catch basin pipe. 3. HW further recommends that the Applicant raise the inlet from the roof runoff proposed at elevation 93.5 to minimize stormwater back flowing into the roof drainpipe. 4. The HydroCAD model and the outlet Detail indicate that the outlet pipe is 8-inches. The plan view calls out a 12-inch pipe. HW recommends that the Applicant adjust the plan view for consistency. 5. on the plan view it appears that the outlet pipe is directed towards the east property line. HW recommends that the Applicant shift the pipe so that it is not discharging towards the abutter. 6. The Applicant intends to capture a section of the existing roof runoff. HW recommends that the Applicant clarify how this roof runoff will be directed into the subsurface system. 7. HW recommends that the Applicant provide drawdown calculations to confirm that the subsurface infiltration system will empty in less than 72 hours. 8. HW recommends that an operation & Maintenance Plan be provided to the homeowner for long term maintenance of the subsurface system. 9. HW recommends that the Applicant clearly delineate the limit of disturbance and whether any trees (greater than 8") will be removed as park of the project. 10. It appears that sections of the Stormwater Report narrative are not consistent with the design including the rainfall amounts listed and the description of the closed drainage system. KAProjects12921121920 Town of Noilh Andover\2102OG 193 Dale StreetlReport1229323_1 st—SW Design Review-198 Dale Street,dou Town of North Andover March 24,, 2022 Page 3 of 3 Conclusions HW recommends, that the North Andover Planning Board require the Applicant to provide a writ,ten response and address the few outstanding comments as part of its review process. We appreciate the o�pportunity to assist the Town of North, Andover on this project review. Please contact Janet Bernardo at 508-833-6600 or at j�er if you have any questions regarding these comments. Sincerely, HORSLEY WITTEN GROUP, INC. Janet Carter Bernardo, P.E. Associate Principal K\Pro jet s\2021\21 020 Town of North Andover\21020G 198 Dale StreeMeport\2203231-1 st—SW Design Review-1 98 Dale Street.dom R iu tiorsley W*Iffen Group f% Sustaillable Environmental Solutions 112 Water Street. Floor.Boston,MA 0210 April 8, 2022 s. Aeon Enright, Planning Director Planning Department Town of North Andover 120 Main Street North Andover, Massachusetts 01845 Fie: Second Stormwator Poor Review 198 Dole Street North Andover, Massachusetts Dear Ms. Enright and Board embers: The Horsley Witten Group, Inc. H is pleased to provide the North Andover Planning Board with this letter report summarizing our second review of the Stormwator Management Deport and Site Plan for the proposed improvements to 198 Cale Street in forth Andover, MA. The plans were prepared by Ranger Engineering Group, Inc., for Paul and Heather Talosia,n (Applicant). The project proposes the construction of a 960 square foot (sf) two-story garage in the noin_di'sohargo zone and a small area of grading in the non-disturbance, zone on a 0.94, acre parcel. The atormwator management for the proposed improvements includes a subsurface infiltration system consisting of concrete galleys and crushed stone. A total of 660 square Beat (sf) of additional impervious area is proposed on site. The property is located within the Watershed Protection District and the house was built in 1956. In accordance with §195-4.18F of the North Andover Zoning Bylaws, the 325'-footNon-Discharge Zone and the I gg-foot Non,, Disturbance Zone from the wetland area located oinsite applies to the Tito. Any surface or subsurface discharge proposed within the Non-Discharge Buffer Zone requires a Special Watershed' Permit. The following additional documents and plans were received by HW in response to our initial March 24, 2022 review letter: • Letter to Forth Andover Planning Department regarding 198 Dole Street Stormwator Review, prepared by Ranger Engineering Group, Inc, dated April 7, 2022 5 pages); • Stormv ater Management Report, 198, Cale Street, North Andover, I" ossoohusotts,l prepared by Ranger Engineering Group, Inc, dated' March g, 2012 , revised April 7, 2022 (914 pages ; and • Site Plan for 198 Cale Street, North Andover, Massachusetts, prepared by Ranger Engineering Group, Inc, dated March g, 2022, revised April 7, 2022 1 sheet). Town of North Andover April 8, 2022 Page 2of3 Stormwater Management Design Peer Review In accordance with §195-4.19. B. (4)All construction in the Watershed Protection District shall comply with best management practices for erosion, siltation, and stormwater control in order to preserve the purity of the groundwater and the lake; to maintain the groundwater fable; and to maintain the filtration and purification functions of the land. HW has the following comments regarding the proposed stormwater management design. The following comments correlate to our March 24, 2022 initial peer review letter. Follow up comments are provided in bold font. 1. The Applicant intends to expand its driveway and construct a 24 foot by 40 foot garage. The driveway runoff will be captured by a catch basin. Runoff from the catch basin will be piped to a subsurface galley system. The subsurface system includes eight (8) 4 foot by 4 foot concrete galley chambers that will be surrounded by crushed stone. The roof runoff from the new garage and a portion of the existing house will also be piped to the subsurface galley system. The proposed galley system has an outlet pipe that discharges north towards the onsite wetland. The discharge point is approximately 100 feet from the wetland and outside of the 100-foot non-disturbance zone. April 8, 2022: No comment needed. 2. currently the chamber outlet tee is set at elevation 96.5 and the inlet from the catch basin is proposed at elevation 95.5. HW recommends that the Applicant raise the inlet pipe as high as feasible in the catch basin and therefore higher in the chambers to minimize stormwater from backing up into the catch basin pipe. April 8, 2022: The Applicant has adequately addressed this comment and has raised the invert of the pipe from the catch basin to the chambers as high as possible. HW has no further comment. 3. HW further recommends that the Applicant raise the inlet from the roof runoff proposed at elevation 93.5 to minimize stormwater back flowing into the roof drainpipe. April 8, 2022: The Applicant has adequately addressed this comment and has raised the invert of the pipe from the roof drain. HW has no further comment. 4. The HydrocAD model and the outlet Detail indicate that the outlet pipe is 8-inches. The plan view calls out a 1 2-inch pipe. HW recommends that the Applicant adjust the plan view for consistency. April 8, 2022: The Applicant has adequately addressed this comment and has adjusted the callout on the plan view as suggested. H`J1l has no further comment. 5. on the plan view it appears that the outlet pipe is directed towards the east property line. HW recommends that the Applicant shift the pipe so that it is not discharging towards the abutter. I°C:IProjects12021\21020 Town of North Andoverl21 o20G 198 Dale Street\Repoi1\220408_2nd_SW Design Review-1 98 Dale Street,docx Town of North Andover April 8, 2022 Page 3 of 3 April 8, 2022: The Applicant has adequately addressed this comment and has shifted the outlet away from the property line. HW has no further comment. 6. The Applicant intends to capture a section of the existing ro�of'runoff. HW recommends that the Applicant clarify how this roof runoff will be directed into the subsurface system. April 8, 2022: The Applicant has clarified that the roof runoff will be captured from surface runoff and not piped. HW has no further comment. 7. HW recommends that the Applicant provide drawdown calculations to confirm that the : I subsurface infiltration system pill empty in less than 72 hours. April 8, 2022: Thee Applicant has provided the requested drawd'own calculations,. HW has no further comment. 8. HW recommends that an Operation & Maintenance Plan be provided to the homeowner for long term maintenance of the subsurface system. April 8, 2022: The Applicant has, provided a Long-Term Pollution Prevention Plan to be provided to the homeowner. HW has no further comment. 9. HW recommends that the Applicant clearly delineate the limit of disturbance and whether any trees (greater than 8,") will be removed as part of the project. April 8, 2022: The Applicant has, clarified the limit of disturbance for the proposed addition. The Applicant has, also noted that 7 white pines and one oak tree will be removed along the east property line. The plan calls out replacing the white poines with arborvitae. HW suggests that the Planning and confirm the number of new plantings,with the Applicant. 101. It appears that sections, of the Stormwater Report narrative are not consistent with the design including the rainfall amounts listed and the description of the closed drainage system. April 8, 2022: The Applicant has revised the Stormwater Report as suggested. HW has no further comment. Conclusions HW is satisfied that the Applicant has adequately addressed our comments. We appreciate the opportunity to assist the Town of North Andover on this project review. Please contact Janet Bernardo at 508-833-66001 or at " r r i if you have any questions regarding these comments. Sincerely, HORSLEY WITT'EN' GROUP, INC. "Ni Janet Carter Bernardo, P.E. Associate Principal KAP reject s\2021\21020 Town of North Andover\21020G 198 Dale.Streeffleport\220408—2nd—SW Design Review_' l 98 Dale Street.docx nrrVVfl,uooi VV00.. I m um uuu uuuuu Horsley W*ifflen Group Sustainable Hymn ntal'Stn 112 Water Street.61"Floor*Boston,NSA 02109 April 25, 2022 s. Joan Enright Planning Director Planning Department 'own of North Andover 120 Main Street North Andover, Massachusetts 0184,.E Ref rooky School - Stormwator Review 1116 and 116,0 Groat Pond load North Andover, Massachusetts Dear Ms. Enright and Board'' Members: The Horsley Witten Group, Inc. (HW) is pleased to provide the! forth Andover Planning Board with this letter report summarizing our initial review of the Watershed Special' Permit Application for the proposed redevelopment for the Boathouse Area and Faculty Housing at the Brooks School located at 1160 and 1116 Groat Pond Road, forth Andover, Massachusetts. The application was prepared for the Brooks School (Applicant) by Whitman & Bingham Associates, LLc. We understand that the entire campus contains appiroxin atoly 1 2.2 acres of land,, and the piroposod project consists of the redevelopment of two previously developed areas of the campus. One phase of the project includes the removal of two existing! boathouses to be replaced with a single boathouse!. The second phase includes removal of an existing residence and replacing it with throe new houses. These projects also include improving the access, drives, constructing a remote tolilot facility, and' landscape improvements. An existing impervious driveway located on 1116 Groat Pond Road will also be removed. The proposed redevelopment results in, a net reduction in impervious surface of approximately 8,255 SF. The Boathouse Project is located substantially within the Non­Disturbance zone, and the Faculty Housing Project is located substantially within the Ikon-Discharges zone and the General zone. The following documents and plans were received by HW4- • Permit Set. Campus Improvements. Boathouse ,and Faculty Housing, Des,ign Teas - A.T. Leonard & Associates, Whitman & Bingham Associates, LLc, Olson Lewis + Architects, and Cube 3, prepared for Brooks School, dated March, 23, 2022 31 sheets), • Application checklist for Notice of Intent, signed by Anthony cleaves, dated March 30, 202 (3 pages ; • Notice of Intent, for Boathouse & Faculty Housing at Brooks School, prepared by Whitman Bingham Associates, L.L C, prepared for Birooks School, dated March 23,, 2o22 21 pages); • Stormwater Analysis, for oathouse & Faculty Housing at Brooks School, prepared by Whitman & Bingham Associates, L.LC, prepared for Brooks School", dated March 23, 2022 (101 pages); HorsleyWlittenxarTi@HorsleyWitienGroupHorsley Witten Group, Inc., Town of North Andover April 25, 2022 Page 2 of 4 • Stormwater Management Report for Boathouse & Faculty Housing at Brooks School, prepared by Whitman & Bingham Associates, LLC, prepared for Brooks School; dated March 23, 2022 (13 pages); • Stormwater System operation & Maintenance Plan for Brooks School campus, prepared by Whitman & Bingham Associates, LLc, prepared for Brooks School, dated March 23, 2022 (8 pages); and • Memorandum in Support of Application, prepared by Smolak & Vaughan LLP, dated March 31, 2022 (11 pages). Stormwater Mana ement Design Review HW offers the following comments concerning the Watershed Special Permit Application considering Section 195-4 of the North Andover Zoning Bylaw (2018) and stormwater management design as per the Massachusetts Stormwater Handbook (MSH) dated February 2008; the North Andover Stormwater Management and Erosion control Regulations (Regulations) adopted February 5, 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. 1. Standard 1 states that no new stormwater conveyances may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the commonwealth. a. The Applicant is proposing a flared end outlet approximately 25 feet from the edge of the wetland. The discharge pipe is directing the overflow from the drip edge capturing the roof runoff. The Applicant has provided the sizing calculations for the riprap apron. HW concurs that the discharge pipe should not cause erosion in the wetlands. The Applicant complies with Standard 1. 2. Standard 2 requires that post-development runoff does not exceed pre-development runoff off site. a. The Applicant is reducing impervious area in the catchment area (5S) draining towards Lake Cochichewick. The Applicant has provided the HydroCAD model of the pre-development conditions, utilizing the model reviewed in 2020 for the conditions that existed before the work currently being conducted on the Brooks School Campus. The Applicant has also provided the HydroCAD model utilizing the combined analysis of the post development work approved in 2020 and the proposed Boathouse and Faculty Housing project. HW has reviewed the calculations and concur that there will be a slight reduction of peak flows from the Brooks School campus with the removal of the existing boathouse, the residence at 1116 Great Pond Road and a section of impervious driveway. The Applicant complies with Standard 2. K:\Projects\202 112 1 020'Fown of North Andoverl21020H Brooks Sclioo]\ReportU20425_Peei•Review l 160 GreatPondRoad.docx Town of North Andover April 25, 2022 Page 3 of 4 3. Standard 3 requires that the annual recharge from post-development shall approximate annual recharge from pre-development conditions. a. The Applicant has reduced impervious area within catchment area 5S and has provided stormwater management improvements throughout the campus as approved in 2020. HW concurs that the post-development annual recharge approximates the pre-development conditions. 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 I inch of volume from the impervious area for water quality. a. The Applicant has reduced impervious area within catchment area 5S and has provided stormwater management improvements throughout the campus as approved in 2020. HW concurs that the removal of the impervious area and the management of the proposed roof runoff of the new boathouse are considered acceptable improvements to the water quality. 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 project is not considered an LUHPPL, therefore Standard 5 is not applicable. 6. Standard 6 is related to projects with stormwater discharging into a critical area, a Zone II or an Interim Wellhead Protection Area of a public water supply. a. The project site discharges into the Lake cochichewick watershed which is considered a critical area. Per Standard 7, redevelopment projects are required to meet Standard 6 only to the maximum extent practicable". Since this project reduces the total impervious surfaces on the site, no additional water quality treatment is required, The Applicant complies with Standard 6. 7. Standard 7 is related to projects considered Redevelopment. a. The project site is considered a redevelopment under the definition: "development, rehabilitation, expansion and phased projects on previously developed sites, provided the redevelopment results in no net increase in impervious area." As such, the project is required to meet the following MSH Standards only to the maximum extent practicable: Standard 2, Standard 3, and the pretreatment and structural stormwater best management practice requirements of Standards 4, 5, and 6. The Applicant is also required to improve existing conditions. b. By reducing impervious area and moving the boathouse further from the edge of lake cochichewick it is HW's opinion that the Applicant is improving existing conditions. The Applicant complies with Standard 7. KAProjects12021121420 Town of North Andover121020H Brooks 5elioolll�eport1220425—PeerReview 1160 GreatPondRoad.docx Town of North Andover April 25,, 2022 Page 4 of 4 8. Standard 8 requires a plan to control construction related impacts including erosion, sedimentation or other pollutant sources., a. The plan set includes erosion and sediment controls for the two projects. HW recommends that the Applicant coins,ider adding a construction fence to clearly demarcate the limit of work in the field. b. HW recommends that the Applicant include a detail for the erosion control blanket., 9. Standard 9 requires a Long-Term Operation and Maintenance (O&M) Plan to be provided. The Applicant has provided an O&M Plan with a revised Site Map that applies to the entire campus. The Applicant complies with Standard 9. 10. Standard 10 requires an Illicit Discharge Compliance Statement to be provided. a., The Applicant has provided a signed version of the Illicit Discharge Statement on the final page of the Stormwater Management Report. The Applicant complies with Standard 10. 11. HW recommends that,the Applicant document the number of trees greater than 10 inches in diameter that will be removed as part of the proposed projects. Conclusions The Applicant has provided reasonable stormwater measures to manage runoff and improve the existing conditions for the proposed Boathouse and Faculty Housing projects. Please contact Janet Bernardo at 8517-263-8193 or at jbernardo@horsleywitten.com if you have any questions regarding these comments. Sincerely, HORSLEY WITTEN GROUP, INC. �'010' I Janet Carter B,ernardo, P.E. Associate Principal CC: Conservation Administrator 1(:\Pt-ojects12021\21 'roxNrii olf Nofth Andover\2102014 Brooks Scliooll\Rel)ort\2,20425—feet-ReviewI 160 GreatPondRoad.docx RANGER ENGINEERING GROUP, INC. 13 Red Roof Lane Suite 203 Salem, NH,03079 Tel: 978-208-1762 M www.rangereng.com April 7, 2022 Jlean, Enright, Planning Director North Andover Planning Department 1201 Main Street North Andover, MA 01845 RE: 198 Dale Street Stormwater Review Dlear Ms,. Enright, Ranger Engiineering, is submitting this letter and the revised plans in response to the peer review conducted by,The Horsley Witten Group for the above referenced property. Our responses to the comments are listed in bold after each of the comments. 1. The Applicant intends to expand its driveway and construct a 24 foot by 40 foot garage. The driveway runoff will be captured by a catch basin. Runoff from the catch basin: will be piped to a subsurface galley system. The subsurface system includes eight (8,) 4 foot by 4 foot concrete, galley chambers that will be surrounded by crushed stone. The roof runoff from the new garage and a portion of the existing house will also be piped to the subsurface galley system. The proposed galley system has an outlet pipe that discharges north towards the on�site wetland. The discharge point is approximately 1010 feet from the wetland and outside of the 100-foot non-disturbance zone. No response required 2. Currently the chamber outlet tee is set at elevation 96.5 and the inlet from the catch basin is proposed at elevation 95.5. HW recommends that the Applicant raise the inlet pipe as high as feasible in the catch basin and' thierefore higher in the chambers to minimize stormwater from backing up into, the catch basin pipe. The pipe invert in the catch basin has been raised to, 96.5 and in the pipe 'Invert in the chambers is raised to 96.0. This is the highest elevation possible to clear the top of the chamber with an 8" pipe. 30: HW further recommends that the Applicant raise the inlet from the roof runoff proposed at, elevation 93.5 to minimize stormwater back flowing into the roof drainpipe. The roof drain pipe has been raised to elevation 96.00. 4. The HydroCAD model and the Outlet Detail indicate that the outlet pipe is 8-inches. The plan view calls out a 12-inch pipe. HW recommends that the Applicant adjust the plan view for consistency. The outlet pipe has been revised to 8" on the plan, view. 5. On the plan view it appears that the outlet pipe is directed towards the east property line. HW recommends that the Applicant shift the pipe so that it is not discharging towards the, abutter. The discharge pipe has been shifted away from the east abutter's, property line. It should be noted that the abutters property is approximately 18" higher than this property. Refer to Photo 1 attached. 0152MIME= RANGER ENGINEERING GROUP, INC. 13 Red Roof Lane Suite 203 Salem, NH; 0,3079 Tel: 978- -1762 www.rangereng.corn 6. The Applicant intends to capture a section of the existing roof runoff. HW recommends that the Applicant clarify how this roof runoff will be directed into the subsurface system. Runoff from this, roof w"1111, be directed to the ground surface at the front of the house where it will flow to the catch basin in the driveway. 7. HW recommends that the Applicant provide drawdown calculations to confirm that the subsurface infiltration system will empty in less than 72 hours., Drawdown calculations have been added to the revised drainage report attached to this letter. 8. HW recommends that an Operation & Maintenance Plan be provided to the homeowner for long term maintenance of the subsurface system. A long-term maintenance p1lan is attached to this letter 9. HW recommends that the Applicant clearly delineate the limit of disturbance and whether any trees (greater than: 8") will be removed as part of the project. The limit of disturbance has been added to the plans. There are approximately 7 white pine trees and one oak along the property line that will be removed. The large trees in front of the house will remain. The trees being removed will be replaced with a more appropriate landscape screening plant such as arborvitae. 10. It appears that sections of the Stormwater Report narrative are not consistent with the design including, the rainfall amounts listed and the description of the closed drainage system. The report, has been revised. I will be in attendance at the April 26, 2,022 planning board meeting to discuss this matter. If any additional comments or questions arise, please do not hesitate to contact this engineer. Sincerely, Benjamin C. Osgood, Jr. PE Senior Engineer ME= RANGER ENGINEERING GROUP, INC. 13 Red Roof Lanie Sui't�e 203 Salem,, NH 03079 Tel-, 978-208-1762 www.rangeretig.com 4 005 4 �ffff P I........... Photo 1: Existing White Pine and oak tree along the property line to be removed RANGER ENGINEERING GROUP, INC. 13, Red Roof Lane Suite 203 Salem, NH 03,079 Tel: 978,-208-1762 www.rangereng.com Ph�oto, 2.-� Trees to remain f LONG TERM POLUTION PREVENTION PLAN 198 DALE STREET, NORTH ANDOVER MIA, 01845 As part of the construction of a new garage, paved driveway, and closed stormwater system, it is the responsibility of the property owner to properly maintain the drainage systems and structures, including drain pipes. The current property owner is Paul & Heather Takesian who will oversee long term maintenance of the stormwater system and will be responsible for compliance with the Long Term Pollution Prevention Plan. Regular maintenance is to include the following: 1. Pavement Sweeping Pavement surfaces shall be swept a minimum of twice per year, preferably just after snow melt and late in the fall. 2. Catch Basin Sumps and Drain Manholes Inspect biannually for the evidence of structural damage, silt accumulation and improper function. Remove accumulated sediments and debris from catch basin sump when sump is more than 25% full and/or annually just after snow melt. 3. Drain Pipes Inspect annually for the evidence of structural damage, silt accumulation and improper function. Clean pipes when sediment occupies more than 20% of pipe diameter. 4. Buried Detention Structures Inspect twice per year for evidence of structural damage, erosion, and sediment accumulation. Inspect outlet structure for proper operation and clogging. 5. Graded Slopes and Rip Rap outlets Inspect every spring for erosion. Repair any erosion by placing loam and seed on slopes and riprap in outlet. Nurtured freshly seeded areas to ensure proper germination and establishment of turf. Each of the stormwater structures listed above is shown on a plan attached as Attachment A. Inspections shall be performed by a qualified person with knowledge of stormwater structures and conveyance systems A report of inspections shall be submitted to the Town of North Andover on an annual basis within 30 days of the end of each calendar year. The requirement and responsibility for the inspection and maintenance of the stormwater system will continue to any subsequent owners of the property. Current Property owner who will be responsible for the operation, maintenance, and emergency repairs of the stormwater system.