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2023.09.28 Staff Report.pdf September 28 2023 Staff Report To: Conservation Commission From: Sarah LaValley RE: Staff Report, September 28 2023 Commission Meeting 5:30 PM Request for Determination of Applicability to determine if septic system replacement in riverfront (Broad Brook) is subject to the Wetlands Protection Act or Northampton Wetlands Ordinance. Kenneth Strong, 384 North Farms Rd, Map ID 7-52 Application Overview: The application proposes construction of a replacement septic system within riverfront area to Broad Brook. Work will take place within an area that is existing maintained lawn, approximately 110 feet from bank. No vegetation removal is proposed. Consistency with the WPA and Northampton Wetlands Ordinance, Staff Recommendations: Work is consistent with Title V requirements as confirmed by the Health Department. A negative determination can be issued by checking box 2 to indicate that work is within riverfront but will not remove, dredge, fill or alter. Include erosion control as shown on plans. Require notification 48 hours prior to work and again when work is complete. Check the box that notes no resource areas are confirmed. 5:45 PM Notice of Intent for Greenway parking lot, affordable home construction and related stormwater improvements within buffer zone. Northampton Office of Planning & Sustainability. 196 Cooke Ave. Map ID 18-22 Application Overview: The application proposes construction of an 18-space bituminous parking lot with accessible spaces and bicycle parking, and four affordable residential buildings with eight parking spaces. The parcel was recently acquired by the City, and the former Moose Lodge was demolished in late 2022. The site has been previously disturbed and includes areas of impervious gravel area. September 28 2023 Staff Report 2 Work is located within buffer zone to bank of an unnamed intermittent tributary to Pine Brook. The stream is unmapped on USGS, and has a 22 acre watershed size, far less than the ½ square mile size needed to otherwise be considered perennial. A stormwater permit was not required since the work area is less than one acre. Roof water will be collected by gutters and underground piping, discharging to the proposed infiltration near the southeast corner of the proposed duplex unit. Site grading is designed to prevent runoff from paved areas from entering this basin. The remainder of the site is proposed to be graded in order to allow as much paved area as possible to sheet flow to the proposed sediment forebay to provide treatment. An existing degraded area within the 0-50 foot zone is proposed to be restored with native conservation mix, and planted with 24 native trees and shrubs. DEP Comments: DEP comments and engineers response are attached. This is a buffer zone only project. Consistency with the WPA and Northampton Wetlands Ordinance, Staff Recommendations: Work is confined to the limits of existing degraded area, and will result in an overall reduction of altered area. Disturbance within buffer zone will decrease from 39,292 sf to 32,668 sf. Alteration within the 50 foot buffer will be reduced from 19,067 to 14,851 sf, and the project will restore additional areas of degraded area. Stormwater treatment should increase water quality; no treatment currently exists. Work is allowed within protected zones (0-50 buffer) as a project affecting protected zones already degraded. Work meets all of the applicable 337-10 (D)(2)(h) standards. Suggested additional conditions: Assessment of plantings after no less than two growing seasons, with a report included with a request for certificate of compliance. Any plantings not surviving at that time to be replaced Construction period best management practices regarding removal and treatment of invasive plant species Permanent condition prohibiting disturbance within the restored and planted areas. Shift plantings to be located outside stormwater structures (some shown on infiltration basin and forebay) The property owner(s) of the residential lot must inspect and maintain the proposed stormwater management system to ensure that the system continues to function according to design and in good working condition. The proposed stormwater management system operation & maintenance plan for Post-Construction must be revised to add inspection and maintenance of the proposed undertrain in the water quality swale and should be recorded at the Registry of Deeds. 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com Berkshire Design Group August 25, 2023 Northampton Conservation Commission Northampton, MA RE: Response to MassDEP Comments on Notice of Intent 196 Cooke Ave – MassDEP File Number WE 246-0774 Dear Commissioners: Berkshire Design Group is the engineer of record for the proposed improvements at 196 Cooke Avenue and prepared design plans for the project that were part of a Notice of Intent submitted by the City of Northampton. We are in receipt of comments from MassDEP on the Notice of Intent, and are providing the following responses as the Commission considers this application: 1. MassDEP: Per 310 CMR 10.05(6)(l), there is no regulatory requirement for a stormwater management system. We acknowledge that a stormwater management system is not required; however, in the context of this project, which is partly parking and access for public conservation land, one of the design goals of the project was to provide an improvement to the existing condition, which includes reducing runoff and improving water quality. 2. However, since a stormwater management system is being created, it must comply with the standards. Per 310 CMR 10.53(1), the commission may require a redesign of the parking lot area to move those areas and the stormwater management system further away from the wetlands such that possibly no BMP’s are required and that sheet flow alone with a well vegetated buffer zone may be adequate based on the site having HSG B soils. The commission may require that pre and post development calculations be run for sheet flow runoff only. As a reminder, roof runoff does not typically require treatment. Both forebays and infiltration basins require ongoing maintenance which often does not get done as required. We note that sheet flow over vegetated areas is likely to provide insufficient treatment from flows off of larger paved areas. While we acknowledge that stormwater management is not required, we believe that some improvement on existing conditions (even if not fully compliant with standards) is better than no stormwater management at all. We have reviewed the site plan and coordinated with Northampton DPW. We have modified the outlets for the proposed stormwater basin designed to capture pavement runoff from the residential site and can now qualify it as a water quality swale instead of a sediment forebay, providing a greater level of water quality treatment. The proposed conservation parking lot has been re-graded to direct runoff to the existing catch basin at the driveway entrance, which will be converted to a stormwater treatment chamber (Contech CDS or equal). The proposed treatment chamber will be owned and maintained by the City. The infiltration basin and water quality swale are designed to require simple maintenance that is achievable by the homeowners in the future residential development. August 25, 2023 Response to MassDEP Comments on Notice of Intent 196 Cooke Ave – MassDEP File Number WE 246-0774 Page 2 of 2 4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com While the project may comply with wetland protection regulations if the proposed stormwater management system were eliminated, it is our opinion that the proposed design is a significant improvement over that alternative design. Sincerely, Berkshire Design Group Chris Chamberland Principal Civil Engineer