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v "FEB-II-OB 10,28 FROf~-DIVISION OP WATER RESOURCES ~~~oQO«<~ ~ --- -~ -~ <br />~~ ~~ ~~ <br />,~~ OF T18: STATE E:fUi31NEER <br />p~ NMutR M~wovaR da <br />13t3 eh~ ~~ fRooia lI10 <br />Pl~rC9~ ~ <br />FAX (~ ~~ <br />w~Yf~i11~M~ <br />John F. Scott, PhD, P.E. <br />Scott Water Engineers <br />1908 Meadowalre Drive <br />Fort Collins, CO 8052,5 <br />June 25, 2007 <br />Re: Substitute 1Na~tar Supply Plan, Timnath Pit CORMS #t\11-89-056AM) <br />SW 114 Sec. 'f 1 ~ N 1l2 N 112 Sec. 14, T6N, R68W, 6th P.M. <br />Wat®r Division 1, Water District 3, Larimer County <br />Period of AplProval: May 1, 2AQ7 throuatt April 30, 2Q08 <br />Contact Phone Number for Dr_ Scott: 970-472-5288 <br />M, - - <br />~ l~r..t <br />a~~ <br />lUrtlaQ>s~tz# <br />6swi~r- Qfl~~t <br />t~«+o <br />ai.. se<npn.N <br />Dear Dr. Scott: <br />Ws have reviESws~d your latter of May 1 Q, 2007, requesting renewal of the above referenced substitute <br />water supply plan to cover depletions caused by an existing mining operation. pan Kahn Gonstrus;,tian <br />CpKC'~ operates this site and provides aggregate for aspha{t and consxe+te paving Plants on the sites- The <br />requirsad f~ of $257.(10 for the renewal of this substitute supply plan has been submitted. The original supply <br />plan was approved oin April 16,199$ at~sd it was most r®cerltiy renewed on July 7, 2004. <br />This plan anticipates a total of 19.1 acres of water surface will be exposed at the site. This area <br />exceeds the a-ea of the water surface currently exposed, but is representative of the maximum water <br />surface that may bs:e exposed during the mining operation. Accordingly, this plan proposes to make <br />replacements of depletions from.evaporation from 18.1 acres of exposed ground water. Based an cun'ent <br />assumptions to be ds~scrlbed herein, the anticipated net depletions an an yearly basis are 67.6 acre-feet, <br />which consists of 47.3 acre-feet per year of evaporation from up to 19.1 acres ssf ground water exposed <br />after December 31, 1980, S.a acre-feet of water lost with mining of up to 200,000 tons of aggregate per <br />year, 3 acre-feet of !sasses from water used for dust control, l.4 acre-#aet of water tost.for grave! washing <br />and 10 acre-feet of water used far equipment wasahing. The total lagged deplet')ons are 65.2 acre-feet <br />which is reflected in the attached Table 1. According to the mfarmatian submitted, na water surface was <br />exposed within the riaclamation permit boundary prior to .lanuary 1, 19f31.No phrsatophyte credit has basin <br />applied to this plan ,and no dewatering is proposed at this mining site under the terms of the substitute <br />water supply plan. <br />The proposed source of replacement water for this pit is 3.5 shares out of a tote) of 64 Sox Elder <br />Ditch shares owned by Don Kahn Construction. The 9.5 shares of ditch water were historically used to <br />irrigate 242.a acres on the Ttmanth Pit properry as fogows: 70.1 acn~s com, 20.6 acres alfalfa and ~ 51.7 <br />acres pasture. A histarical consumptive use analysis assoaated with the 3.5 Box Elder Ditch shares was <br />performed for the irrigated acreages based on the modified Blaney-Griddle evapo-transportation model <br />documented in the Irrigation Water Requirement, Technical Release No. 21, and it was determined to be <br />19}.3 acre-fs~et based on an averags~ ds~livery to the property from 1860 through 7968 of 352 acro-feet <br />(after 1 o'Yo of deiivs:sry loss). The irrigation efficiency on the T~manth property was sastimated for flood <br />irrigation to be 60°/>. Currently the 151.7 acres of irrigated pasture has been dried up. Tha historical <br />consumptive use associated with the 151.7 acres of irrigated pasture was determined to be 121.6 acrsa- <br />feet_ The historical consumptive for the com and alfalfa was limited due to high volume of the irrigation <br />