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I I I I I I I I I I I I I I I I I II I 22. a. -.-.. ----... 1. Continued. 3. industrial wastewater? 4. cooling wate~ (contact and nor.contact) X No Yes X No _Yes If yes, ident1f,)' ',ources. volumes. qual1ty (if other than normal domestic sewage)~ and treatment methods. G~ve the basis or metho~ dology of estimates. I. The project will generate increased rate and volume of stonn water runoff. Hard surfaces such as rOOftops. parking lots and roadways reduce site penneab111ty which results in less percolat1on of stonn water and an increase in runoff rate and vollllle. Ex1st1ng topography slopes generally to the north w1th runoff be1ng d1rected toward the intersect10n of Lex1ngton Avenue and County Road C2. The 5011 ConsErvat1on Service (SCS) ISoil Survey of Wash1ngton and Ramsey Countiesl class1f1es w~st soils at the s1te as Ur~an land-H~yden Kingsley Complex w1th 3-15~ slopes. S011s w1th this classif1cat1on are moderateiy penneable with rapid runoff. The northwest corner of the site has a small area of Dundas f1ne sandy loam wh1ch has modera- tely slo~ penneability and slow runoff. Stann water runoff ponds 1n the Dundas 5011 area and flows to the east to an existing 241 RCP which crosses from west to east undp.r Lex1ngton Avenue. Hayden K1ngsley Soils are SCS Hydrologic Group -BI s011s. The Dundas f1ne sandy loam varies from SCS Hydrologic Group .SI to Group .0.1 Runoff from the development is proposed to be collected by a stonn sewer system. Runoff from approximately 2/3 of the site 1s proposed to d1scharge 1nto sedimentat10n and rate control bash.s. Runoff from the rema1n1ilg 1/3 of the site 1s prOp'Jsed to d1scharge d1rectly 1nto DNR Wetland 201W. It may b~ feas1ble to d1rect some runoff to an ex1st1ng stonn sewer 1n Lex1ngto~ Aven~e. However. th1s would reQu1re evaluation of the existing stonn sewer capacity and coordlnatio~ with Ramsey County. Compl1ance with watershed rate control requirements will be necessary. The area of the site is approx1~tely 30.12 acres comprised of general commercial medium. dens1ty mult1-fam11y housing, and single-fal'Jltly re~td!nt1a1. Runoff voll!lle and disCharge rate were analyzed us10g the SCS Method -TR-55 Orban Hydr~logy For Sr411 Watersheds.1 Predeveloprnent and post~2vp.lopment con- d1t10ns were analyzed. A SCS cur\e number of 70 was ~sed to re~resent predeveloped cond1t10ns. The postdevelopment con- d1t10n analyzed threft subwatersheds. two which d1scharge 1nto ret2nt10n bas1ns and one wh1ch d1~charges off-s1te to the DNR Wet~alld 201'1. 7