The Commonwealth of Massachusetts Executive Office of Energy and Environmental Affairs 100 Cambridge Street, Suite 900 Boston, MA 02114 Charles D. Baker GOVERNOR Tel: (617) 626-1000 Karyn E. Polito Fax: (617) 626-1181 LIEUTENANT GOVERNOR http://www.mass.gov/envir Kathleen A. Theoharides SECRETARY July 16, 2021 CERTIFICATE OF THE SECRETARY OF ENERGY AND ENVIRONMENTAL AFFAIRS ON THE EXPANDED ENVIRONMENTAL NOTIFICATION FORM PROJECT NAME : Quinapoxet Dam Removal PROJECT MUNICIPALITY : West Boylston PROJECT WATERSHED : Nashua EEA NUMBER : 16390 PROJECT PROPONENT : Massachusetts Water Resources Authority DATE NOTICED IN MONITOR : June 9, 2021 Pursuant to the Massachusetts Environmental Policy Act (MEPA; M.G. L. c. 30, ss. 61- 62I) and Section 11.03 of the MEPA regulations (301 CMR 11.00), this project is subject to the mandatory requirement to prepare an Environmental Impact Report (EIR). In accordance with Section 11.05(7) of the MEPA regulations, the Proponent submitted an Expanded Environmental Notification Form (EENF) with a request that I grant a Waiver of the requirement to prepare an EIR. In a separate Draft Record of Decision (DROD), also issued today, I propose to grant a Waiver of the EIR requirement. This Certificate sets forth the issues that must be addressed by the Proponent during permitting and discusses recommendations that were submitted on the project during the MEPA comment period. Project Description As described in the Expanded Environmental Notification Form (EENF), the project includes the removal of the Quinapoxet Dam, located adjacent to the outlet of the Quabbin Aqueduct in the Town of West Boylston (Town), as well as the restoration of the Quinapoxet River in-stream habitat. The project is intended to enable fish and wildlife passage, maintain public river access, maintain flood control, protect water quality, ensure climate change resiliency, and reduce long-term maintenance costs associated with the dam. The project has been designated by the Massachusetts Division of Ecological Restoration (DER) as a Priority Project. EEA# 16390 EENF Certificate July 16, 2021 The dam was constructed by excavating of the riverbed downstream of the dam, which was constructed at-grade, to create a spillway with a 9-foot-high drop. As such, the removal of the dam primarily entails the removal of native substrate behind the dam, and less sediment management than is typically required with dam removals. The wingwalls, spillway, and concrete fish ladder will be removed, the riverbed will be graded upstream of the dam (a length of approximately 600 feet), and fill will be placed immediately downstream of the dam. Riffles and pools will be created in the riverbed upstream of the dam and boulders of various sizes will be relocated within the Quinapoxet River to provide adequate water depths, habitat refuge, and appropriate flow velocities for fish passage. Vegetated areas of sediment deposition within the channel downstream of the dam will be mechanically dredged. Together these actions will create a uniform stream width in the area of the exiting dam, resulting in a decrease in the width of the channel immediately upstream and downstream of the dam as compared to existing conditions. Approximately 3,950 cubic yards (cy) of sediment will be dredged from the channel. Most of this sediment (2,530 cy) will be relocated to the southern bank of the Quinapoxet River in order to formalize an earthen berm between the main channel and the Quabbin aqueduct outlet. Following construction, the berm will have a length of 350 feet with a bottom width of 20- to 30-feet and top width of 4- to 10-feet. An existing overlook/fish platform will be relocated approximately 140-ft downstream, and an existing pedestrian path will be extended to provide public access to the new location of the platform. The project will require two temporary construction access roads, with a width of 12 feet, totaling 1,415 linear feet (lf). The shorter construction access road will be located south of the channel/downstream of the dam, extending off the existing access road to the building on-site. A temporary sediment stockpile area will be located adjacent to this access road. The longer construction access road will extend from River Road to an area south of the channel/upstream of the dam; a temporary staging area will be located south of this road, near the channel. All disturbed upland areas will receive a minimum of 6” of topsoil and be seeded with appropriate seed mixes upon completion of the project. The removal of the dam will occur in three phases. Phase 1 includes the partial removal of the dam. Phase 2 will involve disassembling the remaining portions of the dam, fish ladder, and appurtenances and the removal of the downstream islands and the reconstruction the channel. Phase 3 will formalize the berm between the reconstructed channel and the Quabbin aqueduct outlet. Each phase will require temporary cofferdams to dewater construction areas – Phase 1 will require a 4,150 square foot (sf) (0.10 acre) area to be dewatered around the southern portion of the dam, Phase 2 will require a 77,675 sf (1.78 acre) area to be dewatered surrounding the dam, and Phase 3 will require a 11,900 sf (0.27 acre) area to be dewatered around the exit of the Oakdale Power Station outlet channel. A gravity bypass culvert, consisting of two 5-foot diameter pipes, and four culverts (4-foot diameter pipes) located under a temporary stream crossing, will also be required for Phase 2. Project Site The 2.85-acre project site consists of the Quinapoxet Dam, a section of the Quinapoxet River, and surrounding upland areas. Adjacent to the dam, at the outlet of the Quabbin Aqueduct, is the Oakdale Transfer Facility. The dam is located upstream of two sediment basins serving the Wachusett Reservoir, and in turn is part of the water supply infrastructure for the City of Boston. 2 EEA# 16390 EENF Certificate July 16, 2021 As described by the EENF, the Quinapoxet Dam was constructed in the early 1900’s as part of the Wachusett Reservoir construction project. The dam is owned by the Commonwealth of Massachusetts and is under the care and control of the Massachusetts Department of Conservation and Recreation (DCR) Division of Water Supply Protection. As describe above, the dam was constructed in an atypical way, involving excavation of the riverbed downstream of the dam, which was constructed at-grade, to create a spillway. Unlike most dams, which are constructed to impound waterways and trap sediment upstream, the Quinapoxet Dam was constructed to allow lowering of the gradient of the downstream channel reach for the purpose of reducing flow velocities such that sediment accumulation would occur in the downstream channel, prior to entering the reservoir. According to the Proponent, the dam is no longer necessary to prevent sediment from entering the reservoir, as the downstream channel has stabilized in the century since its construction, and Massachusetts Water Resources Authority’s (MWRA)’s modern reservoir operating system no longer includes the function of the channel.1 The dam includes a 250-foot long, 18-foot-high earthen embankment and a 135-foot long, 6-foot-high stone masonry and concrete horseshoe-shaped spillway weir that spans the Quinapoxet River from bank to bank. The earthen embankment portion of the dam is adjacent to the terminus of MWRA’s Quabbin Aqueduct at the Oakdale Power Station. A concrete pool/weir fishway, 86 feet long and 4 feet wide, is located along the northern abutment. According to the EENF, the Quinapoxet Dam has a Hazard Potential Classification of Class II or “Significant Hazard”. As specified in the Commonwealth of Massachusetts Dam Safety regulations (302 CMR 10.00) failure of a Class II dam may result in loss of life and damage to homes, industrial or commercial facilities, and secondary highways or railroads or cause the interruption of the use or service of relatively important facilities. A 2007 inspection of the dam found the structure to be in fair condition with several deficiencies, including deteriorated concrete at the downstream face and apron of the weir, missing stone masonry at the spillway, scour at the toe of the spillway, minor depressions in the embankment, and voids, missing/displaced stones, scour damage, and leakage in the fish ladder. The EENF indicated that a more recent inspection was not available. The impoundment extends approximately 400 to 500 feet upstream of the dam and is shallow and fairly narrow. The Quinapoxet River bifurcates around a large, vegetated island, converging to a single channel approximately 600 feet upstream of the dam. Wetland resource areas present in the vicinity of the dam include: Bank, Bordering Vegetated Wetlands (BVW), Land Under Water (LUW), Bordering Land Subject to Flooding (BLSF), and Riverfront Area (RFA). The project is not located within mapped Estimated and Priority Habitat of Rare Species as delineated by the Natural Heritage and Endangered Species Program (NHESP) in the 14th Edition of the Massachusetts Natural Heritage Atlas or an Area of Critical Environmental Concern (ACEC). The Quinapoxet Dam is listed on State Register of Historic Places (WBY.905). The Wachusett Reservoir Public Water Supply Watershed is listed as an Outstanding Resource Water (ORW). A portion of the project site was previously regulated under the Massachusetts Contingency Plan (MCP; 310 CMR 40.0000) and assigned Release Tracking Number (RTN) 2-14334. This was associated with arsenic detected in groundwater in 2001 which was later determined to be naturally occurring and not associated with a release of 1 Information regarding the current function of the dam provided in an email from Katherine Ronan (MWRA) to Eva Murray (MEPA Office) sent on July 15, 2021.