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2024-2025 Chavers Mining Resources Substitute Water Supply Plan Page 2 of 8 July 25, 2024 procedural rules in 2 CCR 402-5. The hearing will be waived if the Applicant is able to obtain statements from the owners of all wells within 600 feet, verifying that they have no objection to your use of the proposed well. Fully consumable water from the City of Aurora will be used to replace depletions from the mining operation. The proposed reclamation of the site is a lined reservoir through the construction of acompacted clay liner around the mining area. In accordance with the letter dated April 30, 2010 (copy attached) from the Colorado Division of Reclamation, Mining, and Safety ("DRMS"), all sand and gravel mining operators must comply with the requirements of the Colorado Reclamation Act and the Mineral Rules and Regulations for the protection of water resources. The April 30, 2010 letter from DRMS requires that the Applicant provide information to DRMS to demonstrate theycan replace longterm injurious stream depletionsthat result from mining relate d exposure of groundwater. The DRMS letter identifies four approaches to satisfy this requirement. In accordance with approach nos. 1 and 3, the Applicant has indicated that a bond has been obtained for $3,708,110 through the DRMS for lining of this site to assure that depletions from groundwater evaporation do not occur in the unforeseen event, or events that would lead to the abandonment of the Pit. Depletions The projected depletions for the period of this SWSP consist of net evaporation from exposed groundwater surface area, water removed in the mined product,dust suppression,dewatering,and concrete production. Depletions are calculated for the period of August 1, 2024 through December 31, 2024 as well as for August 1, 2024 through July 31, 2025 (annual or per year depletions) subject to approval condition no. 1. Evaporation Water for dewatering, gravel washing, and dust control will be provided by a series of wash ponds that expose groundwater. The Applicant anticipates that a total of 13.23 acres of water surface will be exposed at the site in the pump basin (10 acres), dewatering trench (0.23 acres), and wash ponds (3.0 acres). 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 attached Table 2. Gross annual evaporation at the gravel pit location is estimated to be 44 inches per year. Net evaporation is defined as gross evaporation minus 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 Brighton 1 NE (record 1974-2022) NOAA weather station. The total net evaporation is 35.78 acre-feet per year, and 13.57 acre-feet for the period of August 1, 2024 through December 31, 2024, as shown on attached Table 2. Computation of evaporation under this SWSP was reduced during the ice-covered period. It is assumed the ice-covered period will occur during the months of December and January based on average monthly temperatures less than 32°F taken from the Brighton 1 NE (record 1974-2022) NOAA weather station. However, for the purpose of this SWSP, the Applicant shall replace the net evaporation depletions from the exposed groundwater surface area that may occur during the assumed ice-covered period for any time that the pit is not completely covered by ice. Computation of the net evaporation during anytime that the pit is not completely covered by ice shall be determined as the pro-rata amount of the monthly gross evaporation rate distribution amount identified in the State Engineer's General Guidelines for Substitute Supply Plans for Sand and Gravel Pits, subtracting the pro-rata amount of the effective precipitation for that period.