2023-12-13_HYDROLOGY - M2004009 (2)

Home Browse Search

ASCI Turnpike Mining Resources SWSP Page 2 of 6 December 13, 2023 Depletions Depletions which occur during this SWSP are evaporation and lagged depletions from past operations. No dewatering will occur during this SWSP. Evaporative depletions at the site occur from within Cells 2A, 213, 3, 4, 5 and 6 summarized in Table A below. The Applicant proposes to replace evaporation from exposed groundwater at the site based upon evaporation atlases in NOAA Technical Report NWS 33 and the SEO monthly distribution factors for sites below 6,500 feet, as shown in Tables 1 and 2 (attached). Gross annual evaporation at the gravel pit location is estimated to be 39 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 Longmont South NCWCD weather station (record 1994-2018). Table A. Summary of Eva orative Depletions. Cells 2A Et 2B Cell 3 Cell 4 Cells 5 and 6 Total Area acres 4.0 4.5 2.93 3.8 15.23 —Unlagged Depletions 10.01 11.26 7.33 9.51 38.10 Total evaporative depletions are estimated at 38.10 acre-feet during this SWSP period, as shown on Table 2 (attached). LaQQed Depletions The IDS AWAS stream depletion model was used to determine the lagged depletions from evaporation and past operations (including dewatering in Cell 3). The aquifer characteristics used in the model are as shown in the following Table B using the alluvial aquifer boundary condition. Table 8: IDS AWAS Parameters and Lagged Depletions from Operations. Transmissivity Specific Yield W distance to X distance to Lagged Cell (gpd/ft) M boundary (ft) stream (ft) Depletions acre-feet 2A and 2B 44,883 20 3,400 3,050 10.08 3 Operations 44,883 20 3,400 650 10.56 3 Dewatering* 44,883 20 3,400 1,065 0.03 4 Operations 44,883 20 1,350 275 7.32 5 Et 6 Operations 44,883 20 1,350 600 9.46 i`The total remaining lagged dewatering depletions from Cell 3 during 2024 is 0.03 acre-feet. There are no more lagged depletions from previous dewatering of Cells 4, 5, and 6 The total lagged depletions for 2024 are equal to 37.45 acre-feet (Table 3, attached). For purposes of this SWSP, the point of depletion for the gravel mining operation shall be on Boulder Creek where Boulder Creek crosses the north line of Section 31, Township 2 North, Range 68 West, 61h P.M. Replacements Replacement water will be obtained through leasing fully consumable replacement water from the Town of Erie ("Erie"). According to the lease dated December 5, 2023 between Erie and the Applicant, Erie will lease 39.15 acre-feet of effluent derived from Erie's Windy Gap Project Units obtained from the Northern Water Conservancy District to be delivered during this SWSP period. Such water will be delivered to the Town of Erie's North Water Reclamation Facility (WDID 0602308) where it discharges to Boulder Creek. The