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HomeMy WebLinkAbout08/28/2019 - Horsley Witten Group Stormwater Peer Review #3 - 481 Sutton Street Horsley Withen Group �� Sustainable Environmental Solutions 294 Washington Street-Smite 801•Boston,MA 02108 857-263-8193 horsleywitten.como August 28, 2019 Ms. Monica Gregoire, Staff Planner Planning Department Town of North Andover 120 Main Street North Andover, Massachusetts 01845 Ref: 31d Stormwater Peer Review North Andover Adult Center 1 Surrey Drive North Andover, Massachusetts Dear Ms. Gregoire 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 Drainage Report and Permitting Plans for the proposed North Andover Adult Center at 1 Surry Drive, North Andover, MA. The plans were prepared for the Town of North Andover (Applicant) by DeVellis Zrein Inc. HW understands that the Applicant is proposing to construct an Adult Center, a parking lot, landscaping improvements, a stormwater management system, and new utility infrastructure. The project proposes to redevelop a 1.5-acre area comprised of multiple lots that currently contain two existing 2-family homes. There are no waterways or wetlands on-site. The area is not associated with any Natural Heritage & Endangered Species Program areas and is outside of the FEMA 100-year flood zone. The following additional documents and plans were received by HW: • Response letter to the North Andover Planning Board, prepared by DeVellis Zrein Inc., dated August 27, 2019, including supplemental stormwater calculations (92 pages); • Site Development Plans, North Andover Adult Center, 1 Surrey Drive, North Andover, Massachusetts, prepared by DeVellis Zrein Inc., dated May 28, 2019, revised August 27, 2019, which includes; o Cover Sheet o Existing Conditions Plan (The Morin-Cameron Group, Inc.) o Layout and Materials Plan C-1 o Grading and Utility Plan C-2 o Planting Plan C-3 o Site Details Sheet C-4 o Site Details Sheet C-5 o Photometric Plan SL-I.B FiorsleyWRten.corn Horsley Wiflen Group, Inc, Town of North Andover August 28, 2019 Page 2 of 13 Stormwater Management Design Peer Review The comments below correlate to our initial review dated July 10, 2019 and our second review dated July 30, 2019. Follow up comments are provided in bold italic font. 1. Standard 1 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 Applicant has analyzed the existing and proposed stormwater discharge rates from the project site at the property boundaries. HW notes that there are some minor discrepancies between the pre- and post-development watershed boundaries of the 1 Surrey Drive application and the 505 Sutton Street application (review recently completed by HW on July 1, 2019). HW recommends that the watershed boundaries under existing and proposed conditions be coordinated between the two projects to the extent possible. The Applicant has adequately responded to this comment and has revised the watershed boundaries. b. The Applicant will also be discharging a majority of the proposed flow towards the municipal drainage system on Surrey Drive. To verify that the outlet of the municipal system will not cause erosion in waters of the Commonwealth, HW recommends that the Applicant show the locations of the municipal drainage system on the plans, provide a narrative describing where the municipal system currently outlets and document that no erosion is currently occurring at the final discharge point. The Applicant has noted that the existing conditions plan will be updated, and a narrative will be provided. HW has not received either of these documents for review. • August 28, 2019: The Applicant has noted that the drain line in Surrey Drive connects into the drainage line on Sutton Street. The Applicant for the development at 505 Sutton Street responded to a similar request and stated that the municipal system outlets off the south side of Osgood Street. A field visit conducted by The Morin-Cameron Group, Inc. identified this area as densely vegetated. No outlet structure was identified and there was no sign of erosion or scour at the record outlet locations. The field crew followed the topography to the nearest wetland and did not observe any erosion in or upstream of the wetlands. • HW recommends that the drain line be provided on the plan set and understands that this addition is being completed by the Town of North Andover. We have 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 provided calculations for the 2-year, 10-year and 100-year, 24- hour events for pre-and post-development conditions. However, per the North Andover Stormwater Regulations, the 0.5-inch storm and the 25-year, 24-hour event calculations also need to be included. K:U'rojects�?018\18065 N Andover On-Call\18065K North Andover Adull CenterAReports\190828_3rcl Stormwater Peer Review .I Suny Drive Adult Center.doex Town of North Andover August 28, 2019 Page 3 of 13 The Applicant has adequately responded to this comment and revised the Drainage Report to include the 0.5-inch and the 25-year storm events. b. Also, the depths of rainfall used for each event shall be as described in the North Andover Stormwater Regulations under Section 7.2 B.b. Specifically noting that the 100-year rainfall amount is 8.6 inches over 24 hours. The Applicant has adequately responded to this comment and revised the Drainage Report utilizing the depths of precipitation as required by North Andover including the 100-year, 24-hour storm event. c. Per North Andover Stormwater Regulations Section 7.2 B.i, pervious lands onsite "shall be considered to be in good condition regardless of existing conditions existing at the time of computation". HW recommends that the Applicant update pervious cover to be in 'Good' condition in the HydroCAD modeling calculations for pre- development conditions. The Applicant has adequately responded to this comment and has revised the pervious surface cover to be in "Good" condition in the Drainage Report. d. The Existing Watershed Map provided by the Applicant does not show topography extending to the south (e.g., into 19 Surrey Drive), HW is not able to confirm if there is any off-site drainage from adjacent properties currently being managed onsite. HW recommends that the Applicant confirm the drainage areas under existing conditions. The Applicant has adequately responded to this comment and has confirmed the watershed boundaries by conducting a site walk and has updated the Watershed Map to include off-site topography extending to the south of the site. e. The time of concentration (Tc) value utilized for the EX-1 drainage area was assumed to be 6 minutes. HW recommends that the Tc flow path be shown on the Existing Watershed Map and calculated, it appears that the lawn area may have a Tc value longer than 6 minutes. The Applicant has adequately responded to this comment by reevaluating and revising the Tc value for EX-1 drainage area. f. It is not clear from the Proposed Watershed Map how the Applicant delineated the subwatersheds or which portions are pervious or impervious. HW recommends that the Proposed Watershed Map include the proposed contours and shading or hatching of areas of impervious cover. Based on the information provided on the Layout and Materials Plan and Planting Plan, it appears that the amount of pervious area is closer to 0.3 acres as compared to the 0.4 acres provided in the HydroCAD modeling calculations. The Applicant has partially addressed this comment, the watershed map has been shaded to indicate pervious areas. HW is not in agreement with the proposed area listed in the HydroCAD calculations by the Applicant. In the proposed conditions HydroCAD model, the Applicant has noted 0.53 acres of UllrojeetsL018\18065 N Andover On-Call\18065k North Andover Adult Center\Reports\1 90828_3rd Stormwater Peer Review_I Surry Drive Adult Center.doex Town of North Andover August 28, 2019 Page 4 of 13 pervious cover, HW believes that this area is closer to 0.45 acres. HW recommends that the Applicant revisit the area provided. • August 28, 2019: The Applicant has revisited the area and confirmed the original value presented. HW has no further comment. g. Under proposed conditions, the Applicant has indicated that the stormwater runoff from the proposed building roof will be collected via a pipe and directed to a rain garden system. HW recommends that the Applicant provide a detail of the roof leaders and means to overflow if the rain garden system backs up. The Applicant has partially responded to this comment, a detail of the roof leader overflow method will be provided by the architect. • August 28, 2019: The Applicant has added spot grades and has adequately addressed this concern. h. The Applicant is showing the use of three rain gardens onsite: two to collect overland flow from the parking lot and another to manage roof runoff. For those collecting runoff overland, it is not clear how the water is being directed to the curb openings and into the rain garden. Also, there does not appear to be any pretreatment provided. HW recommends that the Applicant provide a plan-view detail for these rain gardens showing pretreatment as required by Standard 3 and the MSH, Volume 2, Chapter 2. For the rain garden collecting roof runoff, there are no invert elevations provided for the flared end sections. The Applicant has adequately responded to this comment by providing additional notations on the plans, a small forebay to the rain garden at the front of the building and the FES inverts to the eastern rain garden. i. The Applicant is proposing the use of a subsurface infiltration/detention system to manage a portion of the site. HW recommends that the Applicant clarify the following: i. The Applicant is using an exfiltration rate of 0.27 in/hr, which is consistent with a Hydrologic Soil Group (HSG) C soil. The test pit at the proposed subsurface system indicates that soils are of a sandy loam and sandy loam gravel, which are consistent with HSG B soils. As noted in the MSH, Volume 3, Chapter 1, Page 13, the Applicant should use the HSG group based on test pit data at the actual site in place of the NRCS data provided. The Applicant has adequately responded to this comment by updating the exfiltration rate in the Drainage Report to be consistent with the test pit data. ii. The Applicant has not provided elevations of the 12-inch header pipe or the connecting pipes on the plan or in the detail. The outlet elevations of the subsurface system should be clearly labeled on the plans and details. The Applicant has adequately responded to this comment by adding the outlet elevations of the 12-inch header pipe and the connecting pipes to Sheet C-2. K:AFrojects\2018\18065 N Andover On-Call\18065K North Andover Adult CenterAReports\190828_3rd Stormwater Pcer Review—I Surry Drive Adult Cenler.docx Town of North Andover August 28, 2019 Page 5 of 13 iii. The Applicant has indicated that the outlet invert of the 8-inch pipe (presumably between DMH 6 and DMH 7) is 158 as noted in the HydroCAD model. However, the outlet invert appears to be 157.6 on the site plan. The HydroCAD model should be revised to reflect the elevations proposed in the plans. The Applicant has adequately responded to this comment by increasing the 8-inch pipe (between DMH 6 and DMH 7) to a 12-inch pipe and updating the elevation on Sheet C-2, to be consistent with the HydroCAD model. iv. The subsurface system detail provided on Sheet C-5 does not include information on minimum depth between ground and top of the proposed subsurface system or the proposed elevation at the bottom of the system, both which are required to verify the elevations used in the HydroCAD modeling. The Applicant has adequately responded to this comment and provided the elevations of the bottom and top of the proposed subsurface system to the detail on Sheet C-5. j. The Applicant is proposing the use of Stormceptor STC 450i for four catch basins. However, there are no design calculations provided showing that this model has adequate capacity for the contributing drainage areas, including the water quality flow rate calculations. HW recommends that the Applicant provide these design calculations in its drainage report for each of the four proposed proprietary catch basins. The Applicant has not addressed this comment. The Applicant suggested that the proposed catch basin/water quality units proposed will be determined at a later date after coordinating with the DPW. Sheet C-2 includes notes on catch basin 2, 4, 5, and 6 that the structures will be 80% TSS removal units. HW is not aware of a suitable inlet structure that meets this criteria. HW recommends that the Applicant determine the type of units being proposed prior to approval from the Planning Board. • August 28, 2019: The Applicant has adequately addressed this issue and has provided an additional structure to provide the required TSS removal. k. The Applicant has conducted soil evaluations within each of the subsurface systems and has provided the soil logs in Appendix C of the drainage report. HW requests that the surface elevations of the test pits within the infiltration systems be added to the test logs. The Applicant has adequately responded to this comment and has added the surface elevations of the test pits to the test pit logs. I. HW recommends that the Applicant verify that it is providing adequate separation to groundwater from the bottom of the stone. Furthermore, it is not clear why the Applicant has chosen a lower infiltration rate than the rate associated with the soil type documented in the test pits. 1OProjects\2018\18065 N Andover On-Cal1\1 8065K North Andover Adult CenterAReports\190828_3rd Stormwatcr Peer Review_I Scary Drive Adult Center.doex Town of North Andover August 28, 2019 Page 6 of 13 The Applicant has adequately responded to this comment and has verified that 2 feet of separation has been provided for the system. 3. Standard 3 requires that the annual recharge from post-development shall approximate annual recharge from pre-development conditions. a. In Appendix B of the Drainage Report, the Applicant has provided calculations to address recharge as required by the MSH and Section 7.2 C of the North Andover Stormwater Regulations. HW recommends that the Applicant use the total impervious area within the site under post-development conditions, not only the increase in total impervious area. The Applicant has revised the drainage calculations; however, the Applicant has not provided documentation to verify the provided water quality and recharge volume. HW recommends that the Applicant provide a stage storage table illustrating the volume of water that can be stored within the underground detention system up to elevation 161.65 feet. • August 28, 2019: The Applicant is providing the required recharge volume. No further comment is needed. b. The Applicant has not provided the draw down calculations for the subsurface system. If the subsurface practice is intended for infiltration, the proposed system must be able to drain fully within 72 hours as required by Standard 3. HW recommends that the Applicant provide the required calculations and verify whether the system will be able to drain within 72 hours. The Applicant has adequately responded to this comment and has included the 72-hour drawdown calculations. c. Under the MSH Volume 3, Chapter 1, page 27, the Applicant is required to direct no less than 65% of the site's impervious cover to the practices intended to infiltrate the required recharge volume. Based on the Applicant's HydroCAD modeling reports, it appears that of the 1 acre of impervious area proposed onsite, 0.4 acres is directed to the proposed subsurface infiltration/detention system while the remaining 0.6 acres will drain directly to Surrey Drive and the municipal system. HW recommends that the Applicant adjust the required recharge volume as noted or direct more runoff to infiltration systems. The Applicant has indicated that the drainage design has been modified, however, the Applicant does not direct at least 65% of the site's impervious area toward a best management practice (BMP). HW recommends that the Applicant further revise the drainage design to comply with Volume 3, Chapter 1, page 27 of the MSH. • August 28, 2019: The Applicant has adequately addressed this comment and provided additional documentation from the adjacent project to support its design. 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. 1<:AProjecls\201 S\14065 N Andover On-Cal l\18065K North Andover Adult Cenler\Reports\1908283rd Stormwater Peer Review_I Suny Drive Adult Center.docx Town of North Andover August 28, 2019 Page 7 of 13 a. TSS removal calculations are provided in Appendix B of the Drainage Report include the use of street sweeping for TSS removal credit. In the MSH, Volume 2, Chapter 1, guidance states that a removal rate of 5% requires quarterly cleaning using one of three types of sweepers. However, in the Applicant's Operation and Maintenance Plan on Page 28 of the Drainage Report, the Applicant suggests cleaning on a semiannual basis. The Applicant has revised the Operation and Maintenance Plan to require quarterly sweeping, however, TSS removal spreadsheets are not included in the Drainage Report. HW recommends that TSS removal spreadsheets be added to the report and that the Applicant ensures that the Town agrees with the proposed street sweeping schedule prior to taking credit for it. • August 28, 2019: The Applicant has adequately addressed this comment. b. In addition, the Applicant states that hand sweeping and hand held leaf blowers can be an alternative to street sweeping. HW recommends that the Applicant discuss with the Town the recommended O&M procedures and confirm whether a street sweeping credit is applicable for TSS reductions. The Applicant has adequately responded to this comment by removing the reference to hand sweeping and handheld leaf blowers. c. The TSS calculations provide an assumed TSS reduction for the proposed proprietary devices (Stormceptor STC 450i). HW recommends that the Applicant provide supporting calculations from the manufacturer to ensure that the TSS reduction is adequate to meet Standard 4. Furthermore, MassDEP has provided guidance stating that when the STC4501 is utilized as an inlet catch basin only 25% TSS removal is accepted practice. HW recommends that the Applicant revisit the proposed stormwater treatment practices. The Applicant has not addressed this comment. The Applicant suggested that the proposed catch basin/water quality units proposed will be determined at a later date after coordinating with the DPW. Sheet C-2 includes notes on catch basin 2, 4, 5, and 6 that the structures will be 80% TSS removal units. HW is not aware of a suitable inlet structure that meets this criteria. HW recommends that the Applicant determine the type of units being proposed prior to approval from the Planning Board. • August 28, 2019: The Applicant has adequately addressed this issue and has provided an additional structure to provide the required TSS removal. d. The Applicant has provided TSS reduction for one treatment train (for subwatershed PR-1B) but has not provided a calculation for subwatershed PR-1A. HW recommends that the Applicant provide the TSS calculations for the catchment areas which include driveways and parking areas. The Applicant has indicated that subcatchment area PR-1A has been analyzed for TSS removal and added to the report, however, it does not appear that the Applicant has included any additional TSS removal calculations for KVrojects\22018\18065 N Andover On-Cal1\18065K North Andover Adult Cen1erAReports\190828_3rd Stormwater Peer Review-1 Surry Drive Adult Center.doex Town of North Andover August 28, 2019 Page 8 of 13 subcatchment PRAA. HW recommends that the Applicant revisit the original comment and revise the report as necessary. • August 28, 2019: The Applicant has adequately responded to this comment and provided the requested documentation. e. As noted above in comment 2a, HW recommends that the Applicant provide the analysis for the 0.5-inch storm as required under the North Andover Stormwater Regulations under Section 7.2B.b. The Applicant has adequately responded to this comment and has included the 0.5-inch analysis in the revised Drainage Report. 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. No further comment is necessary. 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 to this project. No further comment is necessary. 7. Standard 7 is related to projects considered Redevelopment. a. The proposed development is considered a new development with an increase of impervious area, therefore Standard 7 is not applicable. No further comment is necessary. 8. Standard 8 requires a plan to control construction related impacts including erosion, sedimentation or other pollutant sources. a. On Sheet C-1, the Applicant appears to be showing silt soxx placed at the limit of work on the north west and a majority of the south side of the limit of work, with the exception of the limit of work located within the 505 Sutton Street Development. A detail is provided on Sheet C-4. HW recommends that the Applicant clarify in the legend the different line types shown for limit of work and limit of work with silt soxx. The Applicant has included the limit of disturbance and silt soxx line on Sheet C-2. The construction sequencing has not been coordinated at this time but will need to be completed prior to any land disturbance. HW recommends that an orange snow I construction fence be placed at the southern property boundary as a visual indicator to the construction operators. • August 28, 2019: The Applicant has added the construction snow fence along the southern property boundary as requested. K:AhojeetsA2018\18065 N Andover On-Call\18065K North Andover Adult Center\Reports\190828_,rcl Stomiwalcr Peer Review_I Scary Drive Adult Center.docx Town of North Andover August 28, 2019 Page 9 of 13 b. The Applicant mentions tree protection and silt fence in the O&M plan on page 30; however, these sediment and erosion control measures are not shown on the plans. HW recommends that the Applicant confirm the location of these items on the plans. The Applicant has changed the silt fence to silt soxx on the plan. The Applicant has not included a tree protection detail in the plan set, HW recommends that a tree protection detail be added. • August 28, 2019: The Applicant has added the tree protection detail as requested, c. In the Drainage Report, under Section 5, the Applicant states that in regard to Standard 8, additional coordination is necessary to determine the sediment and erosion control measures with the adjacent development, 505 Sutton Street. Also, in the O&M plan on page 30 the Applicant states that during construction the contractor shall present a plan for vehicle entrances and washout areas. HW recommends that the Applicant provide an erosion and sediment control plan as outlined in the North Andover Stormwater Regulations under Section 8.1. The plan should include, if applicable, phasing of work with the 505 Sutton Street development, particularly at the shared limit of work area. HW recommends that the plan address: materials and methods for protecting the municipal drainage system on Surrey Drive, protecting trees to remain in the right-of-way on Surrey Drive and Sutton Street, locations and details for construction entrances and washout areas, locations and details for sediment/material stockpiles, dust control and other items as required by this standard. The Applicant has not provided the erosion and sediment control plan as outlined in the North Andover Regulations and coordinated with the development at 505 Sutton Street. A condition that includes the coordination, phasing, construction entrances, and responsibilities may be acceptable to the Planning Board. • August 28, 2019: The Applicant has provided an explanation regarding the coordination of the erosion controls and the construction phasing. The Planning Board may choose to add a condition regarding this coordination. 9. Standard 9 requires a long-term operation and maintenance plan shall be developed and implemented to ensure that stormwater management systems function as designed. a. In the O&M Plan provided on page 28 of the Drainage Report, the Applicant refers to the manufacturer's specifications for cleaning, but does not reference the attachment. The Applicant has indicated that when the TSS removal structure is determined by the DPW, the manufacture's data sheets will be provided with maintenance requirements. HW recommends that the Applicant provide the requested information as soon as it is determined. • August 28, 2019: The Applicant has provided the requested documentation. K:\ProJects\20J8\18065 N Andover On-Call\1 g065K North Andover Adult CenterAReports\190828_3rd Stornwater Peer Review_I Surry Drive Adult Center.docx Town of North Andover August 28, 2019 Page 10 of 13 b. Further, the Applicant states that the `water quality units will be cleaned during the same schedule as the catch basins'. HW recommends that the Applicant clearly state the frequency of cleaning as required by the manufacturer's specifications or recommendations. Also, the Applicant should specify what equipment is required for cleaning these units. The manufacturer states that maintenance is performed with a standard vacuum truck, whereas typical catch basin cleaning can be done with clamshell buckets. The Applicant has indicated that when the TSS removal structure is determined by the DPW, the manufacture's data sheets will be provided with maintenance requirements. HW recommends that the Applicant provide the requested information as soon as it is determined. • August 28, 2019: The Applicant has provided the requested documentation. c. The Applicant does not specify the frequency for inspection and/or maintenance for the proposed rain gardens. Further, many of the maintenance activities outlined in the MSH, Volume 2, Chapter 2 for rain gardens and bioretention areas are not discussed here, such as vegetation management or the repair of eroded areas. HW recommends that the Applicant clarify the O&M procedures for rain gardens. The Applicant has noted that the O&M Plan will be coordinated with the Town of North Andover. HW finds this acceptable however we believe that the designer should provide guidance to the Town operating the site. Maintaining rain gardens is not difficult however HW has witnessed many DPWs decide that it is easier to mow grass then to weed a rain garden and the gardens are eliminated. HW supports the installation of the rain gardens as a low impact development green infrastructure practice. HW recommends that the Town confirm that the rain gardens will be installed prior to approval of the project. • August 28, 2019: The Applicant has added the operation and maintenance of the rain garden to the O&M Plan as requested. d. The Applicant has outlined the O&M for the pervious patio pavers. The pavers are not shown on the plans. The O&M states that that a leaf blower be used at least twice a year for cleaning of debris. HW recommends that the Applicant also address the activities and equipment potentially required if there is ponding, weeding or a covering of the paver joints. Similar to the rain gardens, HW recommends that the Town confirm the installation of the permeable pavers prior to approval of the project. • August 28, 2019: The Applicant has added the operation and maintenance of the pervious pavers to the O&M Plan as requested. e. The Applicant states that the subsurface detention/infiltration system can be accessed by the manholes at the corner of the system. However, these manholes are not within or in-line with the system for proper jetting or vacuuming. HW recommends that clean out ports for the proposed subsurface system should be included, both in the plan and on the detail, with appropriate labels. Also, the 1011rojects\2018\18065 N Andover On-Call\18065K North Andover Adult CenlerAReports\190828_3rd Stormwater Peer Review I Surry Drive Adult Cenler.doex Town of North Andover August 28, 2019 Page 11 of 13 Applicant should also outline the timeframe for inspections and cleanouts in the O&M Plan. The Applicant has adequately responded to this comment and added additional detail to the plans for the infiltration system. f. The Applicant has provided a long-term O&M Plan in the Drainage Report. The O&M Plan should be a standalone document and include a simple sketch to clearly indicate the location of all stormwater practices to be inspected as well as locations for snow storage. HW recommends that the Applicant include a simple sketch that will be provided to the property owner. HW recommends that the O&M Plan with a simple sketch and maintenance log be provided to the operator of the property for acceptance and signature prior to approval from the Planning Board. • August 28, 2019: The Applicant has added the simple sketch to the O&M Plan as requested. g. The Applicant has not provided an inspection and maintenance schedule with routine and non-routine tasks to be performed of the systems as required by Section 9.1A of the North Andover Stormwater Regulations. HW recommends that the inspection and maintenance schedule be provided to the operator of the property for acceptance and signature prior to approval from the Planning Board. h. HW recommends that the property owner sign the O&M Plan in accordance with the North Andover Stormwater Regulations. HW recommends that the final ownership of the property be determined prior to approval from the Planning Board. • August 28, 2019: The Planning Board may choose to condition a signed O&M Plan prior to land disturbance. 10. Standard 10 requires that an Illicit Discharge Compliance Statement be provided. a. The Applicant provided an Illicit Discharge Compliance Statement to be signed by the owner on page 19 of the Drainage Report. HW recommends that the illicit discharge statement be signed by the property owner prior to land disturbance. HW recommends that the final ownership of the property be determined prior to approval from the Planning Board and that a signed illicit discharge compliance be provided. • August 28, 2019: The Planning Board may choose to condition a signed illicit discharge statement prior to land disturbance. 11. Miscellaneous Comments: a. HW has noted the following inconsistencies in the Checklist for Stormwater Report in comparing it to the Applicant's Drainage Report: i. The Applicant has not noted the method they are using to size the infiltration K:AProjects\3018\18065 N Andover On-Call\18065K North Andover Adult CenterAReports\190828__rd Stormwater Peer Review I Surry Drive Adull Center.doex Town 0f North Andover August 28. 2O18 Page 12Of13 BK4PS (page 23\. ii The Ano|iC8rt has stated that runoff from all i[Dp8[Vi}US 8[e8S at the SUB are discharging tO the infiltration 0MP. However, only 8 portion Of the site /SUbVV@te[Sh8d PR-1 A) iS draining b] the proposed SUhaUrf8o8 detention/infiltration SySt8Dl. iii. The Applicant has stated that 8TM0L exists and that documentation has been provided to address th8TK4[)L /p@g825\. HOVVeV8[, DO such diSCUSSiOD O[documentation iS provided iD the Drainage Report. HW has not received u revised StormnwVater Checklist for review. 0 August 28. 2019: The Applicant has provided the requested checklist. h. HVV noted that some drainage pipe di8Ol8t8[S and materials were not shown on the plan. HVV recommends that the Applicant provide 8 drainpipe schedule and calculations showing that the pipes have adequate capacity to convey the proposed f|OvVS. The Applicant has adequately responded Co this comment and has provided pipe calculations im the revised Drainage Report. o. The Applicant should clearly identify the locations of seeding and provide callouts for proposed |OC8tiODS of trees, plants and Sh[UbS' V8FifviDQ that that all plants are native tO Essex County. The Applicant has adequately responded to this comment and has revised the Landscape Plan asrequested. d. The drainage report and plans refer tO 'Surrey Street' iD several locations. The Applicant should revise these documents t8OOte 'GU[[ey [>[iV8' 8S shown OOthe existing conditions plan. The Applicant has adequately responded to this comment and has revised the various documents to note "Surrey 0r]*e". Conclusions HVViS satisfied that the Applicant has adequately addressed our concerns. The Applicant is advised that provision of these comments does not relieve him/her of the responsibility to comply with all TOVVO of North Andover Codes and By-Laws, COD1[DODwe8|th Of M8SS8ChUS8ttS |8wS. and federal regulations as applicable tOthis project. Please contact Janet Bernardo at 5O8-833-68OOO[8i 'b8[O8ndO@hOrS|8yVVitteD.COD1if you have any questions regarding these CODlUOSDtS. SiDCene|y, HC}RGLEYVV|TTEN GROUP. INC. � Janet Carter Bernardo, P.E. Senior Project M8D@g8[ u:u`"ojm/s�2x|x\/0005wx/movc,uo-co|K\nomxmmmmdover/uo|/cm'rhxcpmw\|Yoxzn_3mywmxm/o,Peer Review-/ auor Drive-Auoxc*^ter.dvcx Town of North Andover August 28, 2019 Page 13 of 13 K:AProjects\2018\18065 N Andover On-Call\18065K North Andover Adult Center\Reports\190828_3rd Stormwater Peer Review-I Surry Drive Adult Center.docx