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Andy Rodriguez, P.E. <br />March 17, 2010 <br />Page 2 <br />exposed ground water surface area that may occur during the assumed ice covered period (the <br />months of January and December) for any time that the pit is not completely covered by ice. <br />Computation of the net evaporation during any time that the pit is not completely <br />covered by ice shall be determined as the pro-rata amount of the monthly gross evaporation <br />rate distribution amount identified in the State Engineer's General Guidelines for Substitute <br />Supply Plans for Sand and Gravel Pits, subtracting the pro-rata amount of the effective <br />precipitation for that period. <br />The remaining uses at the site are water lost in mined product, water used for concrete <br />batching and water used for dust suppression. The plan specifies that 20.59 acre-feet of water <br />will be removed in 700,000 tons of mined product, 3.33 acre-feet will be required for dust <br />suppression and 10.43 acre-feet will be required for the production of 85,000 cubic yards of <br />concrete. <br />Dewatering of the site commenced in October 1998 at a rate of 300 gallons per minute <br />and continued through December 2007. Dewatering at the site will start again in January 2010 <br />within cell D. The SWSP accounts for the net accretions credits at the river that occur due to <br />the dewatering operation at the site and for the depletions to the stream system that result from <br />the past dewatering at the site. The depletions from past dewatering at the site during the <br />period of this plan total 205.68 acre-feet. <br />The depletions from evaporation, water, removed in product, dust suppression, concrete <br />batching and dewatering were lagged to the stream system using a Glover analysis and <br />assuming a distance to the no flow boundary of 10,000 feet, distance of the well to the river of <br />5,409 feet, transmissivity of 72,300 gpd/ft and specific yield of 0.2. <br />. The net evaporation and operation depletions from the Shores Pit site during the period of <br />this SWSP are 45.91 acre-feet and the lagged depletions are 61.31 acre-feet (Table 2). <br />Replacements <br />The proposed replacement sources are net accretion credits at the river that occur due <br />to the dewatering operation at the site (cell D).These accretions are applied to this plan against <br />the evaporation and operational depletions at the site. <br />No. 4. <br />A monthly breakdown of depletions and replacements is shown in the attached Table <br />Conditions of Approval <br />I approve the proposed substitute water supply plan in accordance with Section 37-90- <br />137(11), C.R.S., subject to the following conditions: <br />1. This SWSP shall be valid for the period of January 1, 2010 through December 31, 2010, <br />unless otherwise revoked, modified, or superceded by decree. If this plan will not be <br />made absolute by a water court action by the plan's expiration date, a renewal request <br />must be submitted to this office with the statutory fee (currently $257) by November 15, <br />2010. <br />1?ey