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Feb 28 2001 12 O6PM iU1iLE APPLEGATE No 3552 P• 4/1 production occurs for an estimated 260 days during a year, the concrete production facility at the Howe Pit will have a consumptive tzse of approximately 12.8 acre-feat. The concrete production was also distributed in the same percentages throughout the yeaz as the material produced (Table 2). The concrete production facility receives process water from well 19808R, which is now owned by Lafazge. This permit can pump up to 600 gpm and is included in Appendix A. This substitute supply plan will snake replacements for the depletions from concrete production from this shallow, tributary well. The location of well 19808R is shown in Figure 2. A change of ownership form and change of use form for this well permit will be submitted to the SEO in a separate letter. The total operational consumptive uses for the Howe Pit will create depletions of 44.0 acre-feet (Table 2). MINING STREAM DERLETIOI+IS Due to the fact that the site is set back from the river, the evaporative depletions were assumed not to be instantaneous. A stream depletion model was completed for the Howe Pit site to display the lagged effect o£ the depletions (Appendix B). A summary of the monthly stream depletions due to the mining operation can be found in Tablc 4. The stream depletion model for the mining operation was developed under the following assumptions: • The estimated distance from the ac4ive strcam was 350 feet. The location represrnts the down-gradient extent of the exposed surfaces as defined by the mining limits. • The transmissivity was assumed as 45,000 gaVfi/day. This value was assumed to be the same as the average transmissivity value for a test well in the area. Source: Groundwater Circular No. 11, Location C1-67-35 add2 (Appendix B). • The speci$c yield was assumed to be 0.2, which is typical for an alluvial aquifer. • The location of the parallel impermeable boundary was assumed to be a distance of approximately 12000 feet from the live stream. Source: USGS Depth to the Water Table in the Greater Denver Area, Front Range Urban Corridor, Colorado. A separate stream depletion model was completed for the lagged effects of the pumping from well 19808-R due to the different distance from the South Platte River (Appendix C). A summary of the monthly stream depletions due to the well can be found in Table 4. Page 3