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246-0767.pdf Charles D. Baker Governor Karyn E. Polito Lieutenant Governor Matthew A. Beaton Secretary Martin Suuberg Commissioner This information is available in alternate format. Call Michelle Waters-Ekanem, Diversity Director, at 617-292-5751. TTY# MassRelay Service 1-800-439-2370 MassDEP Website: www.mass.gov/dep Printed on Recycled Paper Western Region-Bureau of Water Resources-Wetlands Program Minimum Information and Documentation for Dewatering Plans The Massachusetts Department of Environmental Protection’s (hereinafter “the Department”) Western Region Wetlands Program has determined that a set of site plans and attached information submitted for its review does not clearly demonstrate that proposed activities “will contribute to the protection of the interests identified” in the Massachusetts Wetlands Protection Act, MGL Chapter 131, Section 40 (and similarly that such plans do not clearly demonstrate that the project will prevent “adverse impacts” to the “Aquatic Ecosystem” associated with “Waters of the United States within the Commonwealth”, each as defined at 314 CMR 9.02). Therefore, please review the below criteria and either modify such plans accordingly where pertinent, or contact the Environmental Analyst assigned to your project to further discuss possible changes. Any request to modify any of the below minimum requirements should be submitted to the Department in writing, and should include justifications. Approval to modify will be provided by the Department in writing, and solely at its discretion. 1. Prepare or modify a dewatering plan, which shall minimally include identification of techniques for bypass of water around the area of alteration; and separately, identification of techniques for treatment of residual water (“seepage water”) within the area of alteration. All such plans shall completely segregate bypass water from residual water. This dewatering plan shall include: • Identification of any regulatory “time-of-year” (“TOY”) restrictions governing the proposed work [from the US Army Corps of Engineers “General Permit-Commonwealth of Massachusetts” (“MGP”); any Massachusetts Natural Heritage and Endangered Species Program directive; and any presumptive directions offered by the Massachusetts Division of Fisheries and Wildlife]. The Department will require adherence to TOY restrictions unless the applicant demonstrates that compliance with them is not practicable; • Identification of any “Cold-water Fishery” (as defined at 310 CMR 10.04 and 314 CMR 9.02) within the subject reach where work is proposed, by reference to the Massachusetts Division of Fisheries and Wildlife “Coldwater Fishery Resources Index” (See http://www.mass.gov/dfwele/dfw/fisheries/conservation/cfr/watershed_index.htm); 2 • Use of temporary flume pipes to bypass flowing water in small rivers and intermittent streams, when flowing, and upstream and downstream temporary dams to isolate the work area and protect it from backwatering. Flume pipes shall be equipped with anti-seep collars where they pass through temporary dams, and fish screens on their upstream inverts. Flume pipes shall be sized to adequately handle at least a two-year storm event; • Use of cofferdams to isolate the area of alteration from flowing water in larger rivers, and in reservoirs, lakes, and ponds; • Use of pumps and hose lines to dewater standing water held behind cofferdams, and to dewater residual water and leaked water in isolated work areas. The rating, type, and location of all pumps and the intake and discharge positions of all hoses shall be identified and located on the site plans; • Use of appropriate energy dissipaters and erosion and sedimentation control best management practices at the discharge orifices of all bypass flume pipes and pump hoses; • Treatment of pumped residual water prior to discharge back to resource areas. Techniques such as filter bags, frac tanks, and stilling basins shall be analyzed and specifically proposed; • Salvage of sessile aquatic organisms (vertebrates, crayfish, freshwater mussels, etc.) stranded during dewatering; • Structural and nonstructural best management practices to separate stormwater from the area of alteration during work and while the site is unstable; • Assurance that the substrate of the area of alteration is stable prior to the reestablishment of flow within it. The Department advises that dewatering plans be designed according to Stream Simulation: An Ecological Approach to Providing Passage for Aquatic Organisms at Road Crossings (USDA Forest Service-National Technology and development Program 0877 1801-SDTDC, May 2008) (available at http://www.nae.usace.army.mil/reg/Stream/USFS_StreamSimulationManual.pdf ). This document is very useful, even for projects not located in flowing streams.