08/10/2020 BOARD OF SELECTMEN Agenda Packet

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IF* "DRAFT 42 OCTOBER 19, 2020 ANNUAL TOWN MEETING* i. Artificial recharge or precipitation to groundwater through site design that incorporates natural drainage patterns and vegetation and through the use of constructed (stormwater) wetlands, bioretention facilities, vegetated filter strips, rain gardens, wet (retention) ponds, water quality swales, organic filters or similar-site-appropriate current best management practices capable of removing significant amounts of nitrogen and other contaminants from stormwater. Said stormwater treatment facilities shall be designed and sized to retain up to the first inch of rainfall from their catchment area within the area designed for nitrogen treatment, before any overflow to subsurface leaching facilities and otherwise meet the Stormwater Management Standards and technical guidance contained, in the Massachusetts Department of Environmental Protection's Storm water Management Handbook, as amended, or State-a p p rove d B M P guidance, whichever is stricter Volumes 1 and 2,dated March 1997,for the type of use proposed and the soil types present on the site. Such runoff shall not be discharged directly to rivers, streams, other surface water bodies, wetlands or vernal pools. Except for overflow from stormwater treatment facilities as described above and when there are no other feasible alternatives, dry wells shall be prohibited. ii. Except when used for roof runoff from non-galvanized roofs and for runoff from minor residential streets, all such wetlands, ponds, swales or other infiltration facilities shall be preceded by oil, grease and sediment traps or forebays or other best management practices to facilitate control of hazardous materials spills and removal of contamination and to avoid sedimentation of treatment and leaching facilities. iii. All such artificial recharge systems shall be maintained in full working order by the owner(s) under the provisions of an operations and.maintenance plan approved by the permitting authority to assure that systems function as designed. iv. Infiltration systems shall be located so that no part of any leaching system is located less than one hundred (100) feet from drinking water wells. Any infiltration basins or trenches shall be constructed with a three(3')foot minimum separation between the bottom of the leaching system and maximum groundwater elevation. V. Roadway widening or improvements that increase the amount of impervious area on the redevelopment site by greater than or equal to a single lane width shall meet the requirements of MS4G,P part 2.3.6,a.ii.4(a)—(c)fully. C. The Building Inspector shall require the submission of sufficient plans and specifications to demonstrate the location and nature of proposed stormwater facilities for development under subsection B (1) and shall require their implementation. For development and redevelopment under subsection B (2), the permitting authority shall require the submission of sufficient plans and specifications to demonstrate the location, nature, operation and effectiveness of the proposed stormwater management facilities and practices and shall require their implementation and maintenance., including provisions for deed restrictions and other implementing provisions, as a condition of approval of the proposed development. No permit may be approved for a development unless the permitting authority determines in writing that the proposed system of stormwater management and artificial recharge will achieve the purposes described in Subsection A. Submitted by the Planning Board Explanation: This article is a housekeeping article that will update the-Town's stormwater management practices for compliance with its MS4 General Permit issued by the Environmental Protection,Agency., The Board of Selectmen recommends approval of Article by a vote of The Finance Committee recommends approval of Article by a vote of 9