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r <br />m Bonestroo <br />Rosene <br />Anderllk & <br />Associates <br />Fngtrreefj i Arthllects <br />January 18, 1994 <br />pt0>^ ^ )*» <br />Hi »«-• / ♦ *• •*» <br />• < •• <br />>••«« f M <br />«i 1 •' f • <br />**ir • • t w« <br />mrntm' * <br />if-«>t A tmrn9g\ <br />t H^M- M <br />«Ar ^ »f <br />v*< ; » <br />I IN4«^ 41 . A <br />m>*40 A <br />• i rn%m^\ <br />1 f <br />% • ^ 0 A • A ' <br />' i« .^< i *J <br />' I A>09^ •! <br />m0^%^ P% <br />kM 'V»« * «^< **f <br />^ r <br />»i <br />C tc«^ M <br />.aryr% f tiMi« tr <br />C <br />Vje i »i <br />Wnwe • ►! <br />I t«N 99 <br />HAW A M <br />,:»av Jk HfpA <br />c«ir • n^w »>f <br />\ W<nH M <br />J Zj -^009 ^ <br />•* r» ,t <br />i rt <br />Wyp><' ^•«-*«^ f% <br />wm^ > %0 A 09 f <br />9 %••• It ■ •% <br />• -%t. . » <br />«Aa.M« < mrntm Af <br />y ^ •• <br />.» <br />•*«4r '. • r I <br />r»«M •■ • •« r^ »% <br />I A <br />l« A(» « <br />94 •%«■ <br />• *rt^| <br />Mj. Jeajioc A. MafaurJi, <br />Building acd Zoning Acajinisrator <br />City of Oroco <br />Post Office Bex $6 <br />Ciystal Bay, Minnesota 55323 <br />Re: Tandem ?rcperats <br />File No, 139-1501 <br />Dear Jeanne, <br />Wc have reviewed the runoff and ponding caJculaccns prepared by Coffin & Gronberg. Inc. <br />for Tandem jPropertiea. The propertv is located south of Watertown Road, to the wTst of <br />Old Crystal Bay Road cr. the Coffin Parcel and to the east of Old CtystaJ Bay Road on the <br />Dickey Parcel, in the North Half of Sectsen 4, The calculattoiis are acceptable, however, <br />more information is necessary to evaluate the imparts on the downstjeam properties. <br />Wc expect that many of the septic systems for ibis development will be mound systems. <br />Several of the septic sites are less Lhaa 3 feet above the high water levels of the deterttion <br />ponds. These sites are on the following jots’ <br />COmN PARCEL: <br />Lot 11, primary & ahemate <br />Lot 1, alternate <br />DICKJEY PARCEL: <br />Lot 5, alternate <br />Lot 6, alternate <br />These site locations should be modified to provide a 3 foot elevation above the high water <br />level or the ponds should be modified. <br />It appears that the ponds have been designed as *dry ponds'* with no pensantst standing <br />water. This design should be reviewed by the .Minnehaha Creek Watershed District. A <br />baffle weir detail should be pro'dded that shows hew it will function without standing '••'•ater. <br />Also, each of the pond outlets cn the Dickey parcel consist of two cuberts at different <br />elevations. No detail has been provided that shows the downstream end of the outlet. The <br />elevated culvert will create a high potential for erosion and we recommend a drop manhole <br />structure be added for control <br />The drainage caJculaticns show in most cases that the future runoff will be less than the <br />^sting ninoff. However, the runoff will be concentrated through culverts to the property <br />Jmes which may have an tnpact on the downstream properties. The pond outlet at Lot 5 <br />on the Cornn Parcel is directed con to the Luce Line Tiail. An existing ditch runs easterly