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HomeMy WebLinkAboutPeer Review Memo 1 6.27.2025Comprehensive Environmental Inc. ● Bolton, MA ● Merrimack, NH ● New Britain, CT ● www.ceiengineers.com Brittany DiRienzo June 27, 2025 Conservation Administrator Town of Yarmouth 1146 Route 28 South Yarmouth, MA 02664 Re: Peer Review Services 1282 Route 28 South Yarmouth, MA Dear Ms. DiRienzo: As requested by the Town of Yarmouth, CEI has completed a technical review of the materials and information listed below for the proposed development project located at 1282 Route 28 in South Yarmouth, MA. The proposed redevelopment property will demolish all existing buildings on site and construct (1) a gasoline filling station with four fueling dispensers, an overhead steel canopy, and two double-walled fiberglass fuel storage tanks; (2) a 3,890 square-foot building with convenience store with a drive-thru; and (3) a two-story building with 4 residential units along the southeast corner of the property. This letter includes the findings of our review of the stormwater design components for the proposed project and compliance with the Massachusetts Stormwater Management Standards and the Town of Yarmouth Stormwater Regulations. CEI’s review is based on the following documents prepared by Choubah Engineering Group, P.C.: a. Stormwater Management Report, dated April 2, 2025 b. Site Plans, dated April 2, 2025 Stormwater Comments 1. The development proposes three subsurface infiltration systems designed to completely infiltrate runoff generated from the 100-year storm event, however, the following assessments must be performed to ensure the system will function properly: a. Test pit must be performed at the location and soil layer of all proposed infiltration systems to confirm infiltration capacity. A test pit was not performed at the location of System #1 or #3. b. A mounding analysis is required when the vertical separation from the bottom of an exfiltration system to estimated seasonal high groundwater is less than four (4) feet and the recharge system is proposed to attenuate the peak discharge from a 10-year or higher 24-hour storm (e.g., 10-year, 25-year, 50-year, or 100-year 24-hour storm). The average separation to COMPREHENSIVE ENVIRONMENTAL INCORPORATED 41 Main Street Bolton, MA 01740 508.281.5160 Comprehensive Environmental Inc. ● Bolton, MA ● Merrimack, NH ● New Britain, CT ● www.ceiengineers.com June 23, 2025 Page 2 estimated seasonal high groundwater is just below 4 feet (El. 16.11) based on the test pits provided. The bottom of the stormwater chambers for System #1, 2, & 3 is at El. 20.00. c. Note, per the Yarmouth Stormwater Regulations, the estimated seasonal high groundwater elevation must be adjusted using the Cape Cod Commission adjustment method (Technical Bulletin 92- 001, as amended) in areas to be used for stormwater infiltration. 2. Per the Yarmouth Stormwater Regulations, redevelopment projects must achieve 50% total phosphorus (TP) and 30% total nitrogen (TN) removal in addition to 80% TSS removal from all impervious area under post-construction conditions. Please document how the project meets TP and TN removal requirements in the Stormwater Report. 3. Note the following information on the erosion and sediment control plan: a. For the subsurface infiltration systems, accomplish any required excavation with equipment placed just outside of this area. If the size of the area intended for exfiltration is too large to accommodate this approach, use trucks with low pressure tires to minimize compaction. Keep the area above and immediately surrounding the subsurface structure roped off to all construction vehicles until the final cover is installed (either paving or landscaping). b. Per the Yarmouth Stormwater Regulations, a description of vehicles and equipment fueling procedures, including how fuels and other vehicle maintenance substances will be stored and handled during construction. 4. Note the following information in the O&M plan. a. The proposed Grading and Drainage Plan does not include Infiltration Ditches. If infiltration ditches are not proposed, the O&M plan should remove this reference in the inspection and maintenance procedures. b. Restrictions on the application of fertilizers are required per Section 2.05(2)d of the Yarmouth Stormwater Regulations. We appreciate the opportunity to provide the Town with peer review services. If you have any questions or comments regarding this report, please contact me at 774-843-2007 or cosullivan@ceiengineers.com. Sincerely, COMPREHENSIVE ENVIRONMENTAL, INC. Conor O’Sullivan Project Review Engineer Pareena Deva, P.E. Project Manager