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HomeMy WebLinkAbout2013-04-16 Planning Board Supplemental Materials (55) Eggleston Environmental 32 Old Framingham Rd Unit 29 Sudbury MA 01776 tel 508.259.1137 fax 866.820.7840 April 10, 2013 North Andover Planning Board 1600 Osgood Street North Andover, MA 01845 Attn: Judy Tymon, Town Planner North Andover Conservation Commission 1600 Osgood Street North Andover, MA 01845 Attn: Jennifer Hughes, Conservation Coordinator RE: Butcher Boy Marketplace, 1077 Osgood Street Stormwater Management Review Dear Ms. Tymon and Ms. Hughes: Per your request, I have conducted a technical review of the March 18, 2013 Notice of Intent submitted by Lynnfield Engineering for the proposed Pentucket Bank at the Butcher Boy Marketplace (1077 Osgood Street), with respect to stormwater management. The materials I have received and reviewed to date include the following: § Notice of Intent, Pentucket Bank at Butcher Boy Marketplace, 1077 Osgood Street, prepared for Angus Realty Corporation by Lynnfield Engineering, Inc. and dated March 15, 2013. § Site Plans (C1-10, A210, A211, E-1 & E-2) Pentucket Bank at Butcher Boy Marketplace, 1077 Osgood Street, prepared for Angus Realty Corporation by Lynnfield Engineering, Inc. and dated March 15, 2013. My primary focus in this initial review is on the overall stormwater management approach and design concepts used in the project, as well as its compliance with the Massachusetts Department of Environmental Protection (DEP) Stormwater Management Standards and Regulations, the North Andover Wetlands Bylaw, and the Town of North Andover’s zoning requirements for Site Plan Review and Watershed Protection Districts. It is my understanding that applications for Site Plan Review and a Watershed Special Permit have been filed concurrently with the Planning Board. My review is aimed at assisting both the Planning Board and the Conservation Commission in their respective reviews of the project. The project site is the 7.3 acre Butcher Boy Marketplace property on the eastern side of Osgood Street, immediately north of Great Pond Road and Lake Cochichewick. The proposed project entails the construction of a 3,672 sf bank building with a drive-through and associated parking on a portion of the property currently occupied by a stormwater detention basin and an access road from Osgood Street. As proposed, runoff from the Butcher Boy Marketplace, Stormwater Review 2 April 10, 2013 bank building and most of the parking lot would be conveyed through a closed drainage system with deep sump catchbasins and CDS hydrodynamic separators and then through subsurface extended dry detention systems for flow attenuation and treatment before being discharged through the existing closed drainage system serving the shopping center. That drainage system discharges to municipal drains that ultimately flow to the Merrimack River. The proposed project is entirely within the 250-ft Non-Disturbance Zone to Lake Cochichewick, the town’s water supply reservoir. According to the Zoning Bylaw Section 4.136 (3) the allowable uses in the Non-Disturbance Zone of the Watershed Protection District do not include office or retail use, either by right or by Special Permit (they can be allowed by Special Permit only in the General Zone). It is my understanding, however, that a Variance for the proposed project has been granted by the North Andover Zoning Board of Appeals. My comments are summarized below: 1. The proposed project is entirely within the Zone A for the Lake Cochichewick public water supply, defined by the Massachusetts Drinking Water Regulations (310 CMR 22.02) as including the land area within a 400 foot lateral distance from the upper boundary of the bank of a Class A surface water source. The Zone A boundary should be shown on the site plans. 2. As proposed, the project does not include any recharge of runoff flows, on the basis that the proposed development is within Zone A and the Massachusetts Stormwater Standards require that stormwater infiltration structures be located outside of Zone A. It does not appear that any consideration has been given to providing compensatory recharge elsewhere on the Butcher Boy property, even though a substantial portion of the property is located outside of Zone A. I also believe that runoff from the building roof could be recharged within the Zone A, provided the roof is not galvanized steel or copper. Both the Massachusetts Stormwater Standards and (within the Watershed Protection District) Section 4.136(4)(g) of North Andover Zoning Bylaw do require that the runoff from impervious surfaces be recharged onsite to the maximum extent practicable. Since the surface runoff on this site would be diverted to the Merrimack River, any loss of recharge would represent a net loss in the volume of water draining to Lake Cochichewick. While the relative volume may be small, incremental losses such as this may over time impact both the quantity and quality of water in the reservoir, particularly during sustained drought conditions when the lake is largely groundwater fed. 3. I have several concerns with the proposed “extended detention basins” aimed at providing treatment and flow attenuation for runoff flows. First, there is no indication that they will hold the water quality volume for 24 hours, as is required for extended detention to provide 50% TSS removal through settling of the solids. In addition, the design calls for 6-inches of stone beneath the open-bottom Butcher Boy Marketplace, Stormwater Review 3 April 10, 2013 chambers, making removal of any solids that do settle in the basin virtually impossible. (I note that the O&M Plan does not even call for sediment removal from the systems). Since the invert of the outlet pipe is at the bottom of the stone, the accumulation of solids in the system over time will also limit the flow of water out of the system. 4. The design calls for a poly barrier on the bottom and sides of the extended detention systems to prevent exfiltration, but does not provide any other means of dewatering the systems below elevation 129.6. This should be reflected in the calculation of available storage volume. 5. The low flow orifices in the outlet control structures should be included in the model, as they have the potential to release more water than the other orifices. 6. Pavement runoff to PCB#10 is shown on the plan as discharging directly to the extended dry detention system with no pretreatment and does not meet the requirement for 80% TSS removal. 7. Pavement runoff to PCB#11 and PCB#12 will undergo pretreatment in a CDS unit but will receive no additional treatment before being discharged to the existing drainage system. It, too, does not meet the requirement for 80% TSS removal. 8. A portion of the entrance driveway closest to Osgood Street drains to an existing catchbasin just inside the entrance. It is unclear whether that structure is to be upgraded or replaced as part of the driveway reconstruction. 9. Roof drains from the proposed building are shown as discharging to proposed catchbasins #13 and #14. If the roof drains are to be tied into the drainage system at all, they should not be connected at a catchbasin where the additional flow could mobilize accumulated sediments. Since the roof runoff is considered clean the connection should also be made downgradient of the CDS units in order to maximize their effectiveness for treating pavement runoff. 10. The project site is a busy shopping center and may well meet the DEP threshold for a Land Use with Higher Potential Pollutant Loading (LUHPPL) of 1,000 vehicle trips per day. If so, suitable BMPs are required for all pavement runoff associated with the proposed project and must be sized to treat a 1-inch water quality volume. 11. Due to the loss of groundwater recharge on the project site the proposed project will necessarily increase the runoff volume discharged from the Butcher Boy site to the town’s drainage system in Osgood Street. It should be verified that there are no downgradient flow constrictions or related flooding problems that could be exacerbated by this increase in flow. Butcher Boy Marketplace, Stormwater Review 4 April 10, 2013 12. Vegetative cover on the existing site should be modeled as being in “good” rather than “fair” condition. Based on aerial photos a portion of the area could also be considered wooded. 13. It is difficult to read the existing conditions on Sheets C-3, C-4 and C-5 of the project plans as they are screened too lightly. Sheet C-5 (Site Grading Drainage and Utility Plan) also appears to be missing several grade lines and does not show a connection from proposed DMH#1 to the existing drainage system. 14. Per DEP requirements, the Stormwater Checklist should be stamped and signed by a Professional Engineer. 15. Per the zoning requirements for a Watershed Special Permit the application should include a written certification by a professional engineer stating that the project will not cause any significant degradation in the quality or quantity of water in or entering Lake Cochichewick. 16. The plans should show inspection ports on the subsurface detention systems. 17. I have the following comments on the O&M Plan included with the NOI: § Short-term, construction-related activities should be the responsibility of the site contractor and should be removed from the O&M Plan for inclusion in a separate Erosion and Sediment Control Plan or the Construction SWPPP. § The O&M plan should apply to the entire Butcher Boy Marketplace property and should identify specific measures aimed at improving existing conditions. § The plan should identify the fact that the property is within a watershed protection zone and outline measures to minimize pollutant exposure. § The Emergency Response Plan should also identify the fact that the property is within a watershed protection zone and should include the North Andover Water Department in the parties to be notified in the event of a release. § The O&M plan should identify how the extended detention treatment units are to be cleaned. § Catchbasins and the CDS units should be cleaned a minimum of once per year. § Table 1 (O&M Budget) is missing from the plan. 18. As is indicated on the Stormwater Checklist, the project is subject to the requirements of the EPA Construction General Permit and will require a construction Stormwater Pollution Prevention Plan (SWPPP) prepared in accordance with EPA regulations. The SWPPP should pay particular attention to the fact that the site is located in a water supply protection zone. The SWPPP should be reviewed and approved by the Planning Board and/or Conservation Commission prior to filing and prior to any disturbance on the site. Butcher Boy Marketplace, Stormwater Review 5 April 10, 2013 19. The Erosion and Sedimentation Control Plan (Sheet C-3) should reference the SWPPP. 20. The location of the proposed stabilized construction entrance should be shown on Sheet C-3. 21. The construction sequence should include construction of the retaining wall and placement of fill. 22. The detail for the stabilized construction entrance should specify stone greater than 1”. I appreciate the opportunity to assist the North Andover Conservation Commission and Planning Board with the review of this project, and hope that this information is suitable for your needs. Please feel free to contact me if you or the applicants have any questions regarding the issues addressed herein. Sincerely, EGGLESTON ENVIRONMENTAL Lisa D. Eggleston, P.E.