931 BROADWAY TEUTSCH STUDENT HOUSING 2018-03-07

CITY OF EVERETT STORMWATER MANAGEMENT MANUAL d. Install the leading edge of the blanket into the small trench and staple approximately every 18 inches. NOTE: Staples are metal, U-shaped, and a minimum of 6 inches long. Longer staples are used in sandy soils. Biodegradable stakes are also available. e. Roll the blanket slowly down the slope as installer walks backwards. NOTE: The blanket rests against the installer's legs. Staples are installed as the blanket is unrolled. It is critical that the proper staple pattern is used for the blanket being installed. The blanket is not to be allowed to roll down the slope on its own as this stretches the blanket making it impossible to maintain soil contact. In addition, no one is allowed to walk on the blanket after it is in place. 4. With the variety of products available, it is impossible to cover all the details of appropriate use _ and installation. Therefore, it is critical that the design engineer consults the manufacturer's information and that a site visit takes place in order to insttre that the product specified is - appropriate. Information is also available at the following web sites: � a. WSDOT: (<http://www.wsdot.wa.�ov/eesc/environmental/>) b. Texas Transportation Institute: (<http://www.dot.state.tx.us/insdtdot/orgchart/cmd/erosion/contents.htm>) 5. Jute matting must be used in conjunction with mulch (BMP C121). Excelsior, woven straw blankets and coir(coconut fiber)blankets may be installed without mulch. There are many other types of erosion control nets and blankets on the market that may be appropriate in certain circumstances. 6. In general, most nets (e.g.,jute matting) require mulch in order to prevent erosion because they have a fairly open structure. Blankets typically do not require mulch because they usually provide complete protection of the surface. 7. Extremely steep, unstable,wet, or rocky slopes are often appropriate candidates for use of synthetic blankets, as are riverbanks, beaches and other high-energy environments. If synthetic blankets are used, the soil should be hydromulched first. 8. If the blanket is not long enough to cover the entire slope length, the trailing edge of the upper blanket sliould overlap the leading edge of the lower blanket and be stapled. On steeper slopes, this overlap should be installed in a small trench, stapled, and covered with soil. 9. One-hundred percent biodegradable blankets are available for use in sensitive areas. These organic blankets are usually held together with a paper or tiber mesh and stitching which may last - up to a year. ]0. Most netting used with blankets is photodegradable, meaning they break down under sunlight , (not iIV stabilized). However, this process can take months or years even under bright sun. - Once vegetation is established, sunlight does not reach the mesh. It is not uncommon to find non- degraded netting still in place several years after installation. This can be a problem if maintenance requires the use of mowers or ditch cleaning equipment. In addition,birds and small animals can beco�ne trapped in the netting. Maintenance Standards 1. Good contact with the ground must be maintained, and erosion must not occur beneath the net or blanket 2. Any areas of the net or blanket that are damaged or not in close contact with the ground shall be repaired and stapled Volume ll— Construction Stormwater Pollution Prevention 3-17