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10/1/25,9:19 AM State.co.us Executive Branch Mail-Re: United Companies Colona Pit SWSP Submittal <br /> Good morning, <br /> Upon preliminary review of this SWSP renewal request, I have the following questions: <br /> 1. Previous SWSPs had the below condition. Pursuant to this condition, could you please provide a copy of <br /> this SWSP? <br /> 1. "This SWSP request is for a gravel mine located on land owned in part by the Applicant and in part <br /> by another landowner. in the case where the operator is not the sole landowner, before any <br /> groundwater is exposed on land not owned by the operator, an agreement must be obtained <br /> between the operator and the other landowner (or whoever is the responsible party) and their <br /> successors to identify who is responsible for the operation and continuance of the SWSP and <br /> future augmentation requirements after mining is complete. The agreement must be submitted <br /> to the SEO with any request for renewal of this SWSP." <br /> The portion of the mine located on land owned by others has been reclaimed and released by the DRMS as of <br /> 2019 and is therefore no longer United's responsibility(see attached letter dated 7/11/2019). Previous SWSPs, <br /> through the 2019 through 2021 approval period, provided adequate replacement water for the exposed <br /> groundwater on the adjacent property.As shown on the Figure 1 attached here, the proposed full buildout of the <br /> gravel pit exposed surface area is solely on Oldcastle SW Group, Inc. property. <br /> 2. My initial calculations show that the water from Tri-County and Blue Mesa shown in Table 4 would not be <br /> sufficient. I suspect this may be because the quantities shown in Table 4 are less than what is contracted <br /> and the historical return flows that must be maintained are not accounted for. See the attached <br /> spreadsheet, "Depletions" tab, columns L through X. I would appreciate your review of these <br /> calculations. <br /> Thanks for sending over your calculations for comparison. I wanted to point out that historical return flows <br /> ' associated with the HCU credits are calculated in Column (8)of the attached Table 3 that was submitted as part of <br /> the SWSP renewal request and are accounted for in the "Historical Depletion Credit" in Column (9). <br /> Based on my review of your spreadsheet, it appears that the lagged depletions in Column L calculated using the <br /> URF function are incorrect, which I think may be why we are getting different required replacement amounts. For <br /> example, the lagged depletion calculation for August 2026 (row 21) includes the lagged effect from future <br /> depletions in months September and October being applied to that month.Additionally, the URF appears to be <br /> correct, but I believe the lagged depletions should be calculated using the inverted URF in this case. Let me know <br /> ' if you disagree with my findings, I would be happy to setup a call to discuss. When I calculate the lagged <br /> depletions using the inverted, wrapped URF, I find that we have adequate replacement supplies from the USBR <br /> and TCWCD leases as shown in Table 4, attached here and provided with the SWSP renewal request. We also <br /> compared the lagged depletions calculated using the URF to the unwrapped lagged depletions calculated using <br /> AWAS and found similar results. I am happy to provide this AWAS file to you if you would like. <br /> Additionally, while we do have additional water available from the USBR and TCWCD leases, Table 4 in the SWSP <br /> renewal request only shows the application of the requisite replacement amounts. <br /> 3. 1 may have additional questions when the division office has completed their review. <br /> Understood. <br /> Please let me know if you have any questions. <br /> Regards, <br /> Wen li Dickinson, P.E. <br /> Water Resource Engineer <br /> Denver Office Team 456 Supervisor <br /> https:Hmail.google.com/mail/b/ALGkdOxhJsspQ9WQy6M8ZvEdoQUrzvydSw2AkGT9zE9ZwUt2JrQJ/u/O/?ik=96aa8a08c9&view=pt&search=all&permt... 4/7 <br />