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2023.02.23 Staff Report.pdf February 23 2023 Staff Report To: Conservation Commission From: Sarah LaValley RE: Staff Report, February 23 2023 Commission Meeting 5:30 PM Notice of Intent for low-level outlet replacement within existing Ice Pond drainage structure and related site access and slope protection work. Work proposed within bordering vegetated wetland, riverfront, and land under water (Rocky Hill Pond Brook) City of Northampton, Rocky Hill Road, Parcel 37-119/120. Application Overview: The work is part of a state Municipal Vulnerability Program-funded project to develop ‘design with nature’ green infratrucure based solutions for stormwater flooding and water quality treatment. Site analysis on ten different sites was completed, and examined use of restored and enhanced natural system design (e.g., stormwater depressions, rain gardens and infiltration trenches, floodplain fill removal, wetlands restoration and replication, and open bottomed culverts) to create reductions in flooding vulnerability due to increases in large storm events. These can reduce the need for engineered solutions elsewhere. Several open space areas were included, where potential projects were compatible with conservation values of a site. The Ice Pond project is the first one of these that is now moving forward to the construction stage, using FEMA hazard mitigation funding. The site was historically used as a pond for creation and harvesting of ice. Currently, a 16-inch low- level outlet pipe acts as an outlet control, limiting discharge and resulting in the impoundment of water within the former pond extents. In these instances, the Ice Pond functions as a detention basin that mitigates peak flow rates downstream of Rocky Hill Road and provides flood control and storm damage prevention. The inlet to the 16-inch low-level outlet is located at ground level and frequently becomes clogged with debris, especially leaves and organic material which washes towards this low point from the surrounding vegetated drainage basin. This results in a reduction in the outlet discharge capacity and further exacerbates the impounding effect within the embankment infrastructure, especially during intense rain events which actively convey the leaves and debris towards the outlet pipe. Previous blockages of the outlet pipe have resulted in overtopping of the embankment and flooding of Route 66, causing damage to the roadway and other City-owned infrastructure. The project proposes installation of a low-level outlet grate structure to hold leaves and debris away from the pipe end, improvements to the upper outlet grate structure to decrease the need for maintenance, and increasing the accessibility of both structures to allow for regular maintenance as well as access for inspection during future storms by Construction of a safe roadway to the outlet structures and reinforcement of the emergency spillway over the embankment. Mitigation for the riverfront area work includes planting 18 black chokeberry and common elderberry shrubs,. The low-level outlet will fill 60 square feet of BVW, but lowering the grade in the adjacent area will effectively create new resource area over time. DEP Comments: DEP Comments and applicant responses are attached. Staff has no concerns with the responses as provided. February 23 2023 Staff Report 2 Consistency with the WPA and Northampton Wetlands Ordinance The application includes an assessment in section 5.1 (page 10) regarding compliance with wetlands performance standards. A RFA alternatives analysis is provided on page Work within the Protected Zone under the Ordinance is proposed, but could be allowed at the Commission’s discretion as a project ‘in or affecting protected zones containing areas already degraded or developed,’ and as a ‘Project which will improve the natural capacity of a resource area(s) to protect the interests identified in MGL c. 131, § 40’ as noted in the assessment in 5.2 of the application on page 14. Staff Recommendation Staff-assisted with application, no specific recommendation. Staff walked the site in several prior years when wetland flags were present and do not have concern with boundaries as shown. If the Commission agrees that the work proposed meets applicable performance standards, an order of conditions with standard conditions and any additional conditions necessary to protect the interests of the Act and the Stormwater Management Standards. A condition requiring assessment of plantings along with a request for certificate of compliance. The Commission should discuss construction plans and understand any heavy equipment proposed to be operated within resource areas, and prohibit that if necessary. The Order should reference the existing O&M plan for the drainage structure for clarity, as well as any maintenance that may be necessary for the small roadway. 5:50 PM Notice of Intent for storm drain repair; installation of new drainage pipe and catchbasins, slope stabilization, and walking path replacement. Work proposed within buffer zone to bank and riverfront (Mill River) Northampton DPW, Dryad’s Green, Parcel 31C-13. The applicant has requested a continuation until March 23 at 5:30 PM An Equal Opportunity Employer M/F/V/H February 15, 2023 GZA File No. 15.0167000.00 Northampton Conservation Commission 210 Main Street Northampton, MA 01060 Re: DEP File WE 246-0767, Response to MassDEP Comments Notice of Intent – Rocky Hill Road Northampton, MA 01060 Dear Conservation Commission Members: On behalf of the City of Northampton (“City”, “Applicant”), GZA GeoEnvironmental, Inc. (GZA) offers the following responses to the Massachusetts Department of Environmental Protection (MassDEP) Western Regional Office comments dated February 2, 2023, regarding the proposed Rocky Hill Road Project. Our response format below includes MassDEP’s comment first, followed by bold type that indicates GZA’s response on behalf of the City. MassDEP Comments and GZA Responses [1] Unless otherwise overcome by the applicant and approved by the commission, the presumptions of the interests of the Act are based on the regulatory presumptions found in the preamble to each resource area, not the incomplete list noted in the narrative. GZA recognizes that the preamble to each resource area states the regulatory presumption as to the interests of the Act provided by each resource area. The discussion of specific items regarding the interests provided by each resource area within the Project limits included in the narrative was intended to draw particular attention to those interests given the existing conditions present at the site. At this time, GZA does not seek to overcome the presumptions stated in the regula- tions. [2] The parties should note the provisions of 310 CMR 10.53(7). “The Notice of Intent for any projects involving the construction, repair, replacement or expansion of public or private infrastructure shall include an operation and maintenance plan to ensure that the infrastructure will continue to func- tion as designed. Implementation of the operation and maintenance plan as approved by the Issuing Authority shall be a continuing condition that shall be set forth in the Order of Conditions and the Certificate of Compliance.” A Stormwater Management System Operation and Maintenance Plan for Ice Pond was approved by the Office of Planning and Development for the City of Northampton and was recorded in 2019 at the Hampshire County Registry of Deeds (Book 13287 Page 105). It has been and will continue to be the responsibility of the Ice Pond Association to maintain the system. February 15, 2023 GZA No. 15.0167000.00 Response to DEP Comments Page | 2 Proactive by Design [3] Guidance on dewatering is attached to this file number notification email, if that operation is required to be conducted. GZA reviewed the referenced information on construction dewatering. The Project is not subject to time-of-year re- strictions, nor is it mapped as a “cold-water fishery” as defined at 310 CRM 10.04 and 314 CMR 9.02. If aquatic organisms are observed within the work area following installation of the water control features, they will be relo- cated upstream of the proposed cofferdam. The plans submitted with the Notice of Intent application show the location of the proposed temporary cofferdam to isolate the area of alteration from flowing water. During re-construction of the low-level outlet, incoming stream flows will be routed through the proposed bypass pump and directed into the existing high-flow outlet which dis- charges into the culvert that flows underneath Rocky Hill Road. Given the existing infrastructure, Rocky Hill Pond Brook will not backwater into the work area. Separate/temporary energy dissipation or erosion and sediment control measures are not required at the bypass discharge location as the bypass flows will be discharged into the existing concrete structure and be routed through the existing downstream conveyance. As needed, the construction area protected by the cofferdam will be dewatered by pumping from a filtered low-level sump. Discharge from the sump will be pumped to a Dirtbag® sediment filtration geotextile bag or equivalent prior to discharge back into the resource area. As shown on the plans, a sedimentation barrier is proposed immediately up- stream of the low-level sump to separate stormwater from the existing berm from surface water entering the work site from the adjacent bordering vegetated wetland and stream. Areas of disturbed substrate in the work area will be stabilized prior to the re-establishment of flow to the new low-level outlet. Thank you for this opportunity to clarify the proposed Project. We trust that our responses adequately address the com- ments submitted by MassDEP. We look forward to working with the Commission towards the issuance of an Order of Conditions. Sincerely, GZA GeoEnvironmental, Inc. Rosalie Starvish, MS, P.E., CFM, CPMSM Daniel M. Nitzsche, CPESC, CESSWI, SE Senior Project Manager Consultant / Reviewer Nathaniel Russel, P.E. Principal-in-Charge Cc: David Veleta – City of Northampton MassDEP-WERO