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Frei Hatchery SWSP Amendment St Renewal 2023-2024 (-2025 or -2026 if extended) Page 2 of 6 <br /> June 22, 2023 <br /> evaporation for this 1.1 acre site. The credits for the pre-81 areas are tied to the locations identified on <br /> said map and may not be re-allocated to other areas of groundwater exposure within the gravel pit <br /> boundary. Any pre-81 area that is backfilled will lose the pre-81 exemption should it be excavated in the <br /> future. Additionally, the backfilling of a pre-81 area does not create a credit to be used elsewhere. <br /> According to the SWSP request, no groundwater is exposed at this site outside of the pre-81 area. <br /> Additionally, no material will be mined from this pit during this approval period and the only water <br /> consumed will be pumped from the pre-81 pond for processing. It is estimated that approximately 700,000 <br /> tons of sand and gravel will be imported from offsite and processed at the pit each year. Therefore out- <br /> of-priority depletions will occur from water used for processing mined aggregate based on a 2% moisture <br /> content as well as dust suppression. Out-of-priority depletions will impact the Bull Seep which is a natural <br /> spring-fed tributary to the South Plat west of the pit. The Applicant proposes to replace out-of-priority <br /> lagged depletions from the mining operation using fully consumable water leased from the City of Aurora. <br /> In accordance with the letter dated April 30, 2010 (copy attached) from the Colorado Division of <br /> Reclamation, Mining, and Safety ("DRMS"), all sand and gravel mining operators must comply with the <br /> requirements of the Colorado Reclamation Act and the Mineral Rules and Regulations for the protection of <br /> water resources. The attached April 30, 2010 letter from DRMS requires that the Applicant provide <br /> information to DRMS to demonstrate they can replace long term injurious stream depletions that result <br /> from mining related exposure of groundwater. The DRMS letter identifies four approaches to satisfy this <br /> requirement. In accordance with approach nos. 1 and 3, the Applicant has indicated that a bond has been <br /> obtained for $350,000 through the DRMS for lining of this site to assure that depletions from groundwater <br /> evaporation do not occur in the unforeseen event or events that would lead to the abandonment of the Pit. <br /> Depletions <br /> Consumptive Use <br /> The projected depletions for the period of this SWSP amendment consist of water used for processing the <br /> mined product and for dust suppression. The Applicant projects that they will import from offsite and <br /> process 518,000 tons of product from May to December 2023 and 700,000 tons of product in each subsequent <br /> year through 2026 (for a total of 2,618,000 tons processed during this approval period). Based on a 2% of <br /> mined product by weight calculated as a depletion used for washing, the projected depletions are 7.62 <br /> acre-feet from May to December 2023 and 10.30 acre-feet for each subsequent year through 2026 (for a <br /> total depletion from washing of 38.52 acre-feet). <br /> Water for gravel washing and dust control will be provided by water pumped from the pre-81 pond. The <br /> estimated water used for dust suppression totals 2.22 acre-feet from May to December 2023 and 3.00 acre- <br /> feet for each subsequent year through 2026 (for a total depletion from dust suppression of 11.22 acre-feet). <br /> The total consumptive use at this site is 9.84 acre-feet from May to December 2023 and 13.30 acre-feet for <br /> each subsequent year through 2026 (for a total depletion of 49.74 acre-feet). <br /> Lagged Depletions <br /> This SWSP will account for lagged depletions from past dewatering operations and prior evaporation at the <br /> site located outside of the pre-81 areas. There are several lined gravel pits located between the Frei <br /> Hatchery Pit and the South Platte River. No drains were constructed between or around the pits to facilitate <br /> the passage of groundwater that may mound up gradient of the lined pits. According to the information <br /> provided, the Frei Hatchery Pit depletions will affect the Bull Seep because the water will not make it to <br /> the South Platte River due to the existing gravel pit liner between the river and the pit. The Bull Seep is a <br /> natural spring-fed tributary to the South Platte River that runs along the west side of the Frei Hatchery Pit <br /> permitted area. The seep is up gradient of the lined gravel pits below and travels approximately 1.75 miles <br />