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and artificial recharge of precipitation which is designed to achieve the following purposes shall
<br />be required: to prevent untreated discharges to wetlands and surface waters, preserve hydrologic
<br />conditions that closely resemble pre- development conditions, reduce or prevent flooding by
<br />managing the peak discharges and volumes of runoff, minimize erosion and sedimentation, not
<br />result in significant degradation of groundwater, reduce suspended solids, nitrogen,
<br />phosphorous, volatile organics and other pollutants to improve water quality, and provide
<br />increased protection of sensitive natural resources. To better achieve the aforementioned
<br />purpose of this section, Stormwater Low Impact Development (LID) planning and development
<br />strategies shall be required unless infeasible.
<br />History: Amended 10-4-1999, ATM, Article 32, approved by Attorney General 1-11-2000
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<br />History: Amended 10-19-2020, ATM, Article 14, approved by Attorney General 2-11-2021
<br />History: Amended 10-17-2022, ATM, Article 7, approved by Attorney General 12-23-2022
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<br />B. These standards may be met using the following or similar best management practices:
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<br />1) For compliance with the Performance Standards of this Bylaw, the design of any stormwater
<br />management system shall be consistent with, or more stringent than, the requirements of the
<br />2008 Massachusetts Stormwater Handbook, and meet the applicable requirements below.
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<br />2) For new or redeveloped single or two-family residences, or new non-residential
<br />development, recharge shall be attained through site design that incorporates natural
<br />drainage patterns and vegetation in order to maintain pre-development stormwater patterns
<br />and water quality to the greatest extent possible. Stormwater runoff from rooftops, driveways
<br />and other impervious surfaces shall be routed through vegetated water quality swales, as
<br />sheet flow over lawn areas or to constructed stormwater wetlands, sand filters, organic filters
<br />and/or similar systems be optimized for nitrogen removal and capable of meeting the
<br />pollution reduction requirements below from stormwater.
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<br />(a) utilize site planning and building techniques, including LID planning and design
<br />strategies unless infeasible, such as minimizing impervious surfaces and disturbance
<br />of existing natural areas, pervious reserve or overflow parking areas, multi-level
<br />buildings, parking structures, “green roofs” and storage and re-use of roof runoff, to
<br />minimize runoff volumes and the level treatment required to reduce contaminants,
<br />(b) minimize erosion and runoff from disturbed areas during construction,
<br />(c) provide for the following:
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<br />i. Artificial recharge of precipitation to groundwater through site design that
<br />incorporates natural drainage patterns and vegetation and through the use of
<br />constructed (stormwater) wetlands, bioretention facilities, vegetated filter strips,
<br />rain gardens, wet (retention) ponds, water quality swales, organic filters or
<br />similar-site appropriate current best management practices capable of removing
<br />significant amounts of nitrogen, phosphorus and other contaminants from
<br />stormwater. Said stormwater treatment facilities shall be designed and sized to
<br />retain up to the first inch of rainfall from their catchment area within the area
<br />designed for nitrogen and phosphorous treatment, before any overflow to
<br />subsurface leaching facilities and otherwise meet the Stormwater Management
<br />Standards and technical guidance contained in the Massachusetts Department of
<br />Environmental Protection’s 2008 Massachusetts Stormwater Management
<br />Handbook, or State-approved BMP guidance, whichever is stricter, for the type
<br />of use proposed and the soil types present on the site.
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