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NOV-09-1999 TUE 04:39 PN FAX N0, P, 03/10 <br />kom:)eNdS.FMeId,PhD.N)ao0ynankslntoryarrtrdFarid1b3B6Vaite:~i03}8d1~i1]Ta:LodPotlrrd:KaryMaphodlGemse~lte _Poprlof9iuetdry,Norem6er09,1Al91:69:biPM _ <br />NydroD~-nantlca Inco-~oratad <br />f00l0 !. n Orlw Rd Bey t 11 <br />Pads/ CO 80171 <br />lroroa: rood) ea-0ml' rAx: (coo) en.eoee <br />Novaaber E, 1999 <br />Ms. Lori Potter <br />Kelly/Hagiund/t3arnery ~ Kahn <br />1441 6igbteeath Street, Suits 300 <br />Deaver. CO 80202-1255 <br />RE: Case No. 99-CV-104, Division Z <br />Project No. 9474.01 <br />Doer Ma. Potter: <br />Ae requested, the have completed as evaluation of material submitted to DMC3 by Rocky <br />Mauateirt Materials 8t Asphalt, Jac. We also rovleWed Mr. James Di111e'e 6/04/99 cite lnepealon <br />repots of the quarry as well ae the 11/03/991etter tom Mr. Joteph Ricci, <br />Rociq Mountain MatedaL !b Asphdt, Ina (RMMA) September 14,1999 report to DMG. <br />The use of 1.6 inches of preapitatioa fbr a 2-year, 24-hour storm event is sot corre~. Aa the <br />attached figure iUuatratea, the value is closer to 2,2 inches. When coneideriag a 30•year, 14-hour <br />precipitation event, the valve is about 3,0 »cbea. <br />It appeere the eubmittel hoe celalated runoff using the SCS Cuuve Number Method, We have <br />concluded that a Curve Number of 77 (CH ~ 77) v used is the submittal. Sines the submittal <br />indicates about 803,000 square feet of land Is be»g m»ed, we assume the land is bars ground, <br />When wrwiderag here ground eonditione, only Type A soils (i.e., coarse sand end gravel) will <br />havo CN = 77, It is our opinion that Type B or Type C soils better represent conditions in the <br />quarry having CN values of 86 or 91, respectively. <br />?he following table illustrates projected values for runoff from the quarry based upon the correct <br />CN values, <br /> s-rn, sa-rtit s-YR 24•I~Dt lam u•lflt la-vtt, is•HR <br /> PABC[P11A'1TON RUNOFF PRSCmr!'A7TON R1INOFF <br />CN VALt18 <br />86 2,20 1.00 3.00 1.66 <br />91 2.Z0 1.34 3.00 5.07 <br />Using the above laformatioq the follow»g table Ulustratea our projeoted runoff tom the 805,000 <br />square foot of mined area. <br /> Y•Y$ 2atat Lo•Ya., z4-Iflt <br /> VOLUME VOLt1t18 <br />CN VALUB CU V <br />86 67100 111360 <br />91 89 890 138 860 <br />Wofer Reeouroee <br />Hrdroloplefe • EnOln.e-/t • Plennen <br />