Page 1 - Section4.2.1-SWPPPCutSheet-FiltrexxStormWaterBlanket

Filtrexx ® Storm water blankets are a storm water runoff reduction and permanent vegetation establishment practice used on post-construction soil surfaces. Storm water blankets are intended for application and use where:

• land disturbing activities have ceased, • permanent vegetation is required,

• reduction of pollutant loading in storm runoff is required,

• runoff volume reduction from contributing watershed is necessary,

• reduction in the size of storm water collection or bio-retention ponds, and rain gardens is necessary.

Storm water blankets are designed to act like a sponge for rain water and non-concentrated storm runoff. By holding large volumes of water at and across the land surface, Storm water blankets increase the infltration and evapotransporation of water from rainfall and storm runoff. These processes aid the cycling of water by recharging ground water and atmospheric water vapor. By increasing the land surface roughness, Storm water blankets slow the rate of sheet runoff, allowing it to more readily infltrate the soil surface. Stormwater blankets are also specifcally designed to allow for permanent and sustained vegetation growth.

Filtrexx ® Storm water blankets are surface applied at a depth of 2 in (50mm). Stormwater blankets are used where reduction of storm water runoff and/or permanent vegetation is required or will improve the design and function of the landscape. Storm water blankets are generally applied after land disturbing activities have ceased and where sheet runoff may exist under storm conditions. Storm water blankets should NOT be used in areas of concentrated storm water fow. Storm water blankets should not be used on slopes greater than 2:1 without the use of additional stabilizers or support practices. Filtrexx ® Slope interruption may be seeded and used with Storm water blankets to slow runoff velocity and the potential for soil erosion.

Storm water blankets are designed to absorb water. For every 1% of organic matter, the Storm water blanket will hold approximately 5,500 gal (21 cubic m) of water per acre inch (103 cubic m) (Breedlove, 2006). Storm water blankets are typically 25% organic matter by wet weight and 50% organic matter by dry weight. Alternatively, Storm water blankets typically hold approximately 1.6 oz (45 g) of water per 3.6 oz (100 g) of Storm water blanket (dry weight); 1 gal (0.004 cubic m) of water per 20 lbs (9 kg) of Storm water blanket (dry wt) or per 30 lbs (14 kg) of Storm water blankets (wet wt). This equates to approximately 40 gal (0.15 cubic m) of water per cubic yard (0.76 cubic m) of Storm water blanket and