2022-10-26_HYDROLOGY - M2008082 - Laserfiche WebLink

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Ready Mix Concrete Substitute Water Supply Plan Page 3 of 9 October 26, 2022 The Applicant proposes to replace evaporation from exposed groundwater at the Morton-Holton site based upon evaporation atlases in NOAA Technical Report NWS 33 and the State Engineer's Office ("SEO") monthly distribution factors for sites below 6,500 feet, as shown in attached Table 1. Gross annual evaporation at these gravel pit locations is estimated to be 44.27 inches per year. Net evaporation is defined as gross evaporation less the consumptive use of water by vegetation that naturally occurred at the site prior to construction of the pit. The historical consumptive use was assumed to be equal to the effective precipitation, which was estimated based on the data from the Fort Lupton 2SE (ID 3027, record 1950-1976) and Brighton 1 NE (ID 950, record 1976-2014) NOAA weather stations. The net evaporation rate for the exposed water surface is estimated to be 2.92 acre-feet/acre, as shown on Table 1, Column 6. Total net evaporation for this plan period is 58.89 acre feet, as shown on attached Table 2, Column 2. The projected maximum monthly exposed groundwater surface area at each stage is described in Table 1 below: Table 1 - Maximum monthly exposed groundwater surface area (acres) Month Stage 1 Stage 2 Stage Stage 6B Stage Stage 5 Stage Total 6A 6C/6D 7A Jan 11.0 7.0 0.1 0.2 0.6 0.6 0.0 19.5 Feb 11.0 7.0 0.1 0.2 0.6 0.6 0.0 19.5 Mar 11.0 7.0 0.1 0.2 0.6 0.6 0.0 19.5 Apr 11.0 7.0 0.1 0.2 0.6 0.6 0.0 19.5 May 11.0 7.0 0.1 0.2 0.6 0.6 0.0 19.5 Jun 11.0 7.0 0.1 0.2 0.35 0.6 0.0 19.3 Jul 11.0 7.0 0.1 0.2 1.7 0.6 0.0 20.6 Aug 11.0 7.0 0.1 0.2 1.7 0.6 0.0 20.6 Sep 11.0 7.0 0.1 0.2 1.7 0.6 0.5 21.1 Oct 11.0 7.0 0.1 0.2 1.7 0.6 0.5 21.1 Nov 11.0 7.0 0.1 0.2 1.7 0.6 0.5 21.1 Dec 11.0 7.0 0.1 0.2 1.7 0.6 0.5 21.1 Mined Product In addition to the evaporation, water is lost with the mined product removed from the mine sites as shown in Table 2, Columns 3a and 3b. Brannan projects that they will mine 214,180 tons of gravel during this plan period from Stages 6C/6D below the ground water table and in a dewatered state and subsequently washed, resulting in a depletion of 4% by weight. Brannan projects that they will mine 825,517 tons of gravel during this plan period from Stages 5 and 7A that results in a depletion of 2% by weight. The gravel production from Stages 5 and 7A may consist of the following: 1) material mined above the groundwater table and washed, 2) material mined below the groundwater table, but in a dewatered state, and unwashed, or 3) stock piled material that is washed. The total water lost from gravel production and washing is projected to total 18.46 acre-feet during this plan period, as shown in Table 2, Column 4.