2320 RAILWAY AVE INTERWEST CONSTRUCTION INC 2023-06-12

INTERWEST — EVERETT CONTRACTOR'S YARD INTERIM FILL PROJECT Sitts & Hill Engineers, Inc. CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN Job Number 17,733 . BFMs and MBFMs provide good alternatives to blankets in most areas requir- ing vegetation establishment. Advantages over blankets include: . BFM and MBFMs do not require surface preparation. . Helicopters can assist in installing BFM and MBFMs in remote areas. . On slopes steeper than 2.5H:1 V, blanket installers may require ropes and harnesses for safety. . Installing BFM and MBFMs can save at least $1,000 per acre com- pared to blankets. Maintenance Standards Reseed any seeded areas that fail to establish at least 80 percent cover (100 percent cover for areas that receive sheet or concentrated flows). If reseeding is ineffective, use an alternate method such as sodding, mulching, or nets/blankets. If winter weather pre- vents adequate grass growth, this time limit may be relaxed at the discretion of the local authority when sensitive areas would otherwise be protected. . Reseed and protect by mulch any areas that experience erosion after achieving adequate cover. Reseed and protect by mulch any eroded area. . Supply seeded areas with adequate moisture, but do not water to the extent that it causes runoff. Approved as Equivalent Ecology has approved products as able to meet the requirements of BMP C120: Tem- porary and Permanent Seeding, The products did not pass through the Technology Assessment Protocol — Ecology (TAPE) process. Local jurisdictions may choose not to accept this product approved as equivalent, or may require additional testing prior to con- sideration for local use. The products are available for review on Ecology's website at httpJ/www.ecy.wa.gov/pro,rams/wq/stormwater/newtech/eguivalent.html. BMP C121: Mulching Purpose Mulching soils provides immediate temporary protection from erosion. Mulch also enhances plant establishment by conserving moisture, holding fertilizer, seed, and top- soil in place, and moderating soil temperatures. There is an enormous variety of mulches that can be used. This section discusses only the most common types of mulch. Conditions of Use As a temporary cover measure, mulch should be used: 2014 Stormwater Management Manual for Westem Washington Volume 1I - Chapter 4 - Page 284 SITTS & HILL ENGINEERS, INC. 36 TACOMA, WASHINGTON