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'! ~ <br />E~vir~r~n?e~~:, Ir~c.. <br />LARRY E. O'BRIAN 7985 VANCE DRIVE, SUITE 205A <br />FOUNDER ARVADA,COLORADO 80003 <br />R E C E I `, E D 303-423-7297 <br />G C C FAx 303-423-7599 <br />Jttly 22, 2002 JUL 2 2 20G2 <br />Bi11 McIntyre Division of Minerals and Geology <br />RECEfVED <br />Colorado Division of Water Resources <br />1313 Sherman St, aslo JUL 2 .a ~ <br />Denver, CO 80203 WATER RES01/RCpS <br />STATE EN~INEEa <br />r•pj J. <br />Deaz Bill: <br />RE: Temporary Substitute Supply Plan <br />A1beR Frei and Sons, Inc. <br />Hazeltine Pit N~ <br />MLRB Permit N M-77-153 <br />The following information is based on our meeting in May 2002 regarding how to <br />calculate the Consumptive Use (CU) for the vegetation on the site and come up with net losses <br />at the mine associated with lake area. In a previous submittal we established the total lake area <br />the needs matte-up water for this mine is 55.92 acres $. This packet atntains two sets of tables <br />showing ore scenario as if the dewatering pumps failed and activities ceased, leaving 55.92 <br />acres of lake and one scenario as if no more than 5 acres of open water will exist during . <br />dewatering. Neither scenario have numbers for product loss since mining has ended at this mine <br />and in a short time the site will be turned over to Denver Water Department. <br />Frei sold this site to Denver Water Department for future construction of a water storage <br />reservoir. The sales contract says Frei has to supply evaporation makeup water as long as they <br />aze mining. Once mining ended, Denver would be responsible for the evaporation loss off the <br />lake until the reservoir is constructed. To the best of our knowledge, no plans for reservoir <br />design or construction have been submitted to the OSE or D.M.G. at this time. <br />In this submittal I have tried to stay consistent with our June discussion as best as I <br />could. I found a CSU program, South Plaltt Constrmpllvs Uss (Cln Model ($PCUM) to <br />calculated the Blaney-Griddle Consumptive Use number (CU) and used it as the base for the <br />evapotranspiration numbers in this packet. This program is more sophisticated than my <br />approach but I feel it gives us a better idea of historic water use at the site as it was close to my <br />single year calculations in other submittals. This program made it easy to calculate the <br />Consumptive uses from two crops. <br />During our meeting we discussed using two methods to calculate the historic B-C <br />numbers for the site. One was to use the 7046 x Total Precip. or the second was to calculate the <br />Potential Evapotranspiration (PET) for the vegetation cover. Since the ground water table was <br />within 24 inches of the surface prior to mining we thought using the PET method would be most <br />advantageous. The SPCUM program will calculated the B-C without using any input water. It <br />calculates an Irrigation Water Required (IWR) number to show how much additional water <br />would need to be added to the crop, taking Into account the Effective Rainfall (BR) for the crop <br />