Laserfiche WebLink
CITY OF EVERETT STORMWATER MANAGEMENT MANUAL <br /> � <br /> 2-to 3-foot high,eztra stength filter fabric supported by hcated 4 x 4-inchs can be used as a ' <br /> divider. Altcmauvely,staked straw bales wiapped with filter fabric(geotextile)may be used. If � <br /> the pond is more thari 6 feet deep,a aifTerent mechanism must bc proposed. A riprap <br /> embanlanent is one acceptable mcthod of separation for dceper ponds. Other desi�s that satisfy <br /> the intent of this provision are allowed as long as tha divider is permeable,swcturatly sound,and <br /> designed to prevent erosion under ot azound t6e barrier. <br /> 2. To aid in detetmiaing sediment depth, 1-foat intervals above the pond bottom shall be <br /> prominently marked on the riser or a staff gauge. <br /> 3. IF en embankment of more than 6 feet is proposed,the pond must comply with the criteria <br /> contained in Volume fll,Chapt�2.;.3,regarding dam saFety for detention BMPs. M elecnonic <br /> version of the Dam Safety Guidelines is available in PDF focmat at <br /> <www.ecv.wa.gov/programs/wr/damsldss.html>. <br /> 4. The most common stcuchval failure of sedimentation ponds is caused by piping. Piping refers to <br /> two p6enomena: (1)water seeping through fine-gtained soil,etoding the soil grain by grain and <br /> fortning pipcs or tunnels; and(2)water under pressure tlowing up�vard through a granutaz soil <br /> with a heed of sufficient magnitude to causc soil grains to lose contact and capability for support. <br /> 5. The most critical conshvction sequences to prcvent piping will be: <br /> a. Tight connections between riser and barrel and other pipe wnnections <br /> b. Adequate anchoring of riser <br /> c. Proper soil compection of the embanlanent and riser footing <br /> d. Proper conshuctian of enH-seep devices. <br /> Maintenance Standards <br /> 1. Sediment shall be removed from the pond wheo it reaches I—foot in depth. <br /> 2. Any damage to the pond embankments or slopes shall ba repa'ved. <br /> 3.3.19 BMP C250: Construction Stormwater Chemical Treatment <br /> Purpose <br /> This BMP applies when using stormwatcr chemicals in batch treatment or tlow-t6rough trcatment. <br /> Condifrons of Use <br /> Fotmal written apptoval from Ecology and t6e City is requ'ved for the use of chemical treatmeot <br /> mgardless of site size. The intention to use Chemical Trcahnent shall be indicated on the Notice o(Intent <br /> for coverage under the General Constcuction Permit. Chemicul treatment systems shoulJ be designed as <br /> part of thc GSW PPF,not after the fact. Chcmical treatment may be used to correct problem sitcs in <br /> limilcd circumstanccs with formal writtcn approval from Gcology and thc Local Pcrtnitting Author,ry. <br /> The Ciry must be notified at the application phase of the project review(or thc time that Ihe SGPA <br /> detemunation on the project is pedormed)that chemical heatment is proposed. [f it is added after this <br /> stagc,an addendum will be necessary and may result in projcct approval dclay. <br /> Design and Installation Specf/ications � <br /> Given tte complexity of this BbfP,additional infocmation is not provided in this Manual. The 20005 � <br /> DOE Stortnwater Managcment Manual must be used to design and implement conshuction stormwater <br /> chemical trcatmcnt. <br /> Volume II— Constructron StormwaterPollution P��vention <br /> 3-65 <br />