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Urban development results in increased impervious surfaces, causing an increase in runoff and degradation of water quality and stream habitat. Stormwater control measures (SCMs), also known as urban best management practices (BMPs) are used to reduce these impacts. In Virginia, 15 SCMs have been approved for use in site development, and a corresponding fact sheet was developed for each. New technologies are continually being developed and implemented within SCMs, so a new series for these “Innovative Stormwater BMPs”, was created. The 2nd in this series addresses Regenerative Step Pool Storm Conveyance (RSPSC). RSPSC is a unique technology being implemented to reduce erosion, recharge groundwater, and improve water quality and stream habitat at stormwater outfalls. Published version

Hypotheses Channel instability in Minebank Run is caused by high shear stresses generated during even relatively frequent storm events. Retrofitting the Minebank Run watershed with additional watershed stormwater controls will reduce channel incision and bank failure (will compare environmental site design (ESD) only, traditional downstream controls only, and combination of both). Had Minebank Run been developed with ESD channel incision and degradation would have 1) been prevented, or 2) been reduced. Current channel degradation in tributaries to Little Seneca Creek are the result of recent large magnitude storm events, which are typically not well controlled by ESD. Had the Clarksburg watershed been developed using traditional stormwater control measures (SCMs), more extensive channel degradation would have occurred. A combination of ESD controlling small storms and SCMs controlling larger events is necessary to protect stream channels against erosion.

Extended detention ponds (EDs) are dry detention ponds that provide 12 to 24 hours of runoff storage during peak runoff events. Releases from the ED ponds are controlled by an outlet structure. During a storm event, as the discharge restriction is reached, water backs up into the ED pond. The pool slows flow velocities and enables particulate pollutants to settle. Peak flows are also reduced. Revised P 426-134

A stormwater filtering practice treats stormwater runoff by passing it through and engineered filter media consisting of either sand, gravel, organic matter, and/or a proprietary manufactured product, collecting it in an underdrain, and then discharging the effluent to a stormwater conveyance system. Revised P 426-131

Constructed Wetlands are low cost and sustainable engineered best practice to reduce stormwater pollution.

A wet swale is an engineered, BMP arranged in a straight line that is designed to reduce stormwater pollution. It consists of a shallow, gently sloping channel with broad, vegetated, side slopes and slow flows. Wet swales typically stay wet because the bottom of the swale is below the water table. This is done to encourage the growth of wetland vegetation. Revised P 426-130

A dry swale is a shallow, gently sloping channel with broad, vegetated side slopes. Water flow is slowed by a series of check dams. A dry swale provides temporary storage, filtration, and infiltration of stormwater runoff. they should remain dry during periods of no rainfall. It is a BMP designed to reduce pollution runoff reduction and pollutant removal and is part of a site's stormwater treatment practice. Revised P 426-129

Discussion of grass channels as a storm water conveyance system VT/1219/426-122(BSE-271P)

Permeable pavement on the top layer is efficient for storm water run off.

Discussion of devices that intercept, divert, store, and release collected roof runoff from rainfall for later use as an alternative water supply VT/0919/426-125(BSE-274P)

A biorentention cel, or rain garden, is a best management practice (BMP) designed to treat stormwater runoffs from roofs, driveways, walkways, or lawns. Where it can be used, how it works, what it does, maintenance, performance, limitations, expected cost Revised 426-128

Ponds or lakes which provide treatment and storage of stormwater.