3900 BROADWAY BASE FILE 2016-01-01 MF Import

CITY OF EVERETT STORMWATER MANAGEMENT MANUAL d. Install thc Icading edge of thc blanket into the small trcnch and staple approximetely � evcry 18 inches. NOTE� Staples are metal, U•shaped,and a minimum of 6 inches�ong. Longer staples arc used in sandy soils. Biodegradable stakcs are also available. e. Roll the blaolcet slowly down the slope as installer walks backwards. NOTE: The blankct rests against thc installa's legs. Staples arc installed as the blanket is wvolled. It is critical tha:lhe proper staple pattem is used for t6e blanket being installed. The blanket is not to bc allowed to roll down t6e slope on its own ac this stretches the blanket making it impossiblc to maintain soil contact. In addition,no one is allowed m walk on the blanket after it is in olace. 4. With the variety of products available, it is impossible to cover all thc details of appropriate use and installadon. Therefore,it is critical that the dcsig�cnginccr consults the manufacturer's information and t6at a site visit takes place in order to insure that the product speci6ed is appropriatr,. Information is also available at ttie following web sites: a. WSDOT: (<y�://www.wsdot.wa.eov/eesGenvironmentalh) b. Texas Transporiation Institutc: (<h�:/lww�v.dot.state.tx.uslinsdtdot/orgchact/cmd/erosiocJcontents.htm>) S. lute matting must be used in conjunction with mulch(BMP C121). Excelsior,woven shaw blankets and coir(wconut fiber)bl;u�kets 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 gencral,most nets(e.g.,jutc matting)requ've mulch in order to prevent erosion because thcy have a fairly open structure. Blankets rypically do not require mulch becausc thcy usually pro�ide completc protection of t6e surface. 7. Extremcly steep, unstable,wet, or rocky slupes are often appropriate candidates for use of synthetic blankets,as are riverbanks,beac6es and other high-energ/environtnents. ff synthetic blankets are used,the soil s6ould be hydromulched first. 8. If thc blanket is not long cnough to cover the cntire slopc length,.hc trailing edge of the upper blanket should ovedap the Icading cdge of the lower blanket and be stapled. On steeper slopes, this overlap should bc installcd in a small trench,stapled,and covered with soil. 9. Onc-hundrcd perocnt biodegradable blankets are available for use in sensitive arcas. Thesc organic blankcts azc usually hcld together with a paper or fibcr mcsh and sfitching which may last up to a ycar. 10. Mosl netting uscd with blankcts is photodegradablc,meaning they break down uoder sunlight (not W stabi6zcd). Howcvcr,this process can takc months or ycars cven undcr hright sw. Once vcgctation is established, sunlight does not rcach the mesh. lt is cot uncommon ro find non- degreded netting still in place sevcral years aftcr installation. This can be e problem if mainttnancc requires the use of mowers or ditcL cleaning equipment. In addition,birds and small animals can become trapped in the netting. Maintenance Standards 1. Good contact a�th the ground must be maintained,and crosion must not occut beneath the net or blankct 2. My areas of the net ur blanket that aze damaged or no!in close contact with the ground shall be repaired and staplcd Volume II—Constn.�ction Stormwater Pollution P�evention 3-�7