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STOR;�i WAT[It SI'I L PLAN �fAY 20, 2003 <br />:1UGUSTA 1VOODS COND0�91NIUi�IS P,\G[ G <br />POTGNTIAL PR013LG�IS <br />Tl�c downstrcam system appcars to have adequate capacity with no adverse impacts to thc <br />adjacent properiies. <br />Scdimcnt discharge from �hc site should be minimal due to settling vaults that arc proposed tor <br />thc sitc. There wcrc no obscrved sediment discharges from the do�vnstream properties. <br />Strcambank crosion should nnt be a problem, as the detention f'acilities proposed for the site �� ill <br />restrict thc rcleasc of stonmvater runoff to dic cxisting rates. The downstre�m channel apperos to <br />bc adequately stabalized by the existing vegetation. <br />No discharge of sronmvater to thc �Rouud�vater is proposed. There are no known violatians oi' <br />�vatcr quality downstrcam on ihc sitc. <br />No spills or disch�rgc of priority pollutants arc anticipatcd from this residcntial dcvclopmcnt or <br />wcis obscrvcd during thc downstrcam reconnaissance. <br />Prevention and ��urce Control will be addressed in Section VI of this report. <br />UONNSTRGAivI C�iPraC17'Y <br />Based on the downstrcam channcl dimensions past thc first cuhcrt the capacity of thc system is <br />i0 cfs. Scc thc att. ��hcd Floir�naster'"'printout. <br />DO�VNS"Cl2CAAi D9I1'IGATION <br />No downslrcam mitigation is proposed 'ocyond providing a storm drainagc systcm tha! mccts thc <br />rcyuirements of die City of Evcrett Stoilmvater Mnnagement �lunual. <br />l PS"CRG,o�1 [3ASIN <br />I he upstream basin tributary to dic wedand corrid.or has bcen analyscd to detemiinc the rcquired <br />culvert size to be placed under the roadway at the weUand crossings. The culvett has also been <br />sizcd to allow for tish passagc. Thc �ish Passagc Guidclincs: Culvert Lr�tn!/ntiors from section <br />111-3.3.4 of the DOG Manu�l �verc uscd in the design of tlic cuh�ert. Thc design has been based <br />upon the rcquiremenis, as listed in Table III-2.5 I�ish Passage Design Criteria for Culvert <br />Installation. Thcsc rcyuircmcnts arc as following: <br />1. Qf0°'o shoulJ not cxcecd 4 it/s through the cul��ert. Q10% for a 2 yr 24 hr sto�n less <br />than d4 cfs is cqual ro the 2 yr 24 lir stomi event. In this case the two year 2=1 hr storn� <br />is 13.6 cfs. Thcrctorc Q10% = the 2�r 24 hr stonn. <br />2. Thc pipc bottom sheuld be countersunk by a minimum of '_'0% of the heieht of the <br />cuh crt. <br />3. ���linimum �low dc��th sh.tll bu O.S ft. <br />V <br />�.��..:..,.� :ra.:�,:,�:�.<�.,�,.x�,�.<:,r.nJau�rcac�..m�-,icssro��m'r.oc�WHlsrm <br />