Laserfiche WebLink
Sievers Pit M-77-098 SWSP, Oldcastle SW Group, Inc. Page 5 of 13 <br /> September 30, 2025 <br /> Additionally, there is a 1.9-acre storage pond which does not expose groundwater. This pond <br /> was filled during the 2013 SWSP free river conditions and will have additional water <br /> delivered to it as needed to replace water consumed during the washing process or <br /> evaporated from the surface of the pond. The total gross evaporative loss from the 1.9-acre <br /> storage pond is 7.13 acre-feet per year. <br /> These evaporative losses were calculated using the State Engineer's Guidelines for Gravel <br /> Pits at elevations below 6,500 feet, gross evaporation of 45 inches per year from the NOAA <br /> Technical Report NWS 33 Map 3, and average annual precipitation of 20 inches per year that <br /> was distributed monthly from the Glenwood Springs #053359 station (1900-2006) of which <br /> 70% was credited for the net evaporation calculation associated with the exposed <br /> groundwater. <br /> Total evaporative losses are 9.45 acre-feet per year. <br /> Water Lost with Mined Product <br /> Groundwater will also be consumed during the process of mining aggregate. Before July <br /> 2009, the aggregate production at Sievers Pit occurred above the groundwater table; <br /> therefore, the decree in case no. 83CW65 did not account for the amount of water lost with <br /> the mined product, since there was no groundwater diversion. <br /> For the purpose of this SWSP, Oldcastle anticipates mining below the groundwater table a <br /> maximum of 225,000 tons of aggregate per year, resulting in an annual water loss of 3.31 <br /> acre-feet, assuming two percent (2%) water weight due to the dewatered state of the mine. <br /> An additional 2% of water is lost due to washing in the above-described 1.9-acre surface <br /> water pond. Therefore, total water loss associated with the mined product is 6.62 acre-feet <br /> per year (both groundwater and surface water depletions). <br /> Dust Control <br /> The maximum amount of water used for dust control is anticipated to be 15.0 acre-feet per <br /> year, which is an increase of 5.5 acre-feet over the amount identified in Case No. 83CW65. <br />