Page 7 - USDA Compost sock use

5

Utilization of Compost Filter Socks

(Agronomy Technical Note 4, January 2011)

Figure 5 Compost flter sock biofltration system

Figure 6 Vegetated compost flter socks

Compost flter socks may be seeded at the time of manufacture and installation if used for permanent applications, such as biofltration, LID, or green in-frastructure projects. Seed is easily blended with the compost media prior to flling the mesh net sleeve. Seed selection and rate should be determined based on local climate and site conditions and vegetation requirements. Native vegetation should be selected when possible (fg. 6).

Installation

Following installation guidelines is essential for proper feld function and optimum performance of compost flter socks. No trenching is required. Compost flter socks may be placed on bare soil, grass, erosion con-trol blankets, or paved surfaces.

• Land surface should be prepared by mowing grass or making soil or paved surfaces smooth. • Compost flter socks shall be placed perpendicu-lar to stormwater fow, across the slope, swale, ditch, or channel.

• Compost flter socks shall be placed on contours. • On soil and vegetated surfaces, under sheet fow conditions, compost flter socks shall be staked on 10-foot (3 m) centers. Under concentrated fow conditions compost flter socks shall be staked on 5-foot (1.5 m) centers.

• Stakes shall be driven through the center of the compost flter sock and installed a minimum of 8 inches (200 mm) into the existing soil, leaving a minimum stake height of 2 inches (50 mm) above of the compost flter sock.

• Stakes shall be 2 inches (50 mm) by 2 inches (50 mm) hardwood stakes; for severe runoff or sedi-mentation conditions or loose soil conditions, such as fll slopes, metal stakes can be used. • Lose compost may be used to backfll the com-post flter sock to connect the ground and com-post flter sock interface.

• Edges of the compost flter socks shall be turned upslope to prevent fow around the ends of the compost flter socks.

• Compost flter socks may be installed on top of any erosion control blanket.

• If used as a check dam, the center of the compost flter sock shall be a minimum of 6 inches (150 mm) below the bank of the swale or channel. • If used as a drain inlet protector, compost flter socks shall fully enclose the drain.

• If used as a curb inlet protector, compost flter socks shall not be higher than the height of the curb.

• If used as a solids separator or dewatering de-vice, the compost flter socks shall be placed in a ring and fully enclose polluted effuent or manure slurry.

• Compost flter socks may be seeded for perma-nent, LID, and in situ biofltration applications.