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Ms. Joanna Williams <br />October 31, 2007 <br />Page 2 <br />The slung wall was anticipated to be approved by October 31, 2007. However, due to <br />legal proceedings associated with a leak in the slung wall, it is now anticipated that the slurry <br />wall will not be repaired until February 2008, and testing of the slurry wall will not be completed <br />until May 2008. The attached Tables 2 and 3 present the updated consumptive use, depletions, <br />and replacements resulting from the further delay in the slurry wall approval. <br />The water from the dewatering pond, is discharged into the Henderson Water Ski Lake <br />(Figure 1), a reclaimed and unlined gravel pit, located north of the Sand and Gravel Mine <br />property. Evaporative losses from this lake are augmented as per the decree entered in Water <br />Court Case No. 82CW393. Furthermore, 120t1i Estates Partners made observations of the <br />Henderson Water Ski Lake while discharging water into the lake (from their 120`' Estates Sand <br />and Gravel Mine currently in operation), and only a very slight increase in the water level in the <br />lake resulted. Therefore, we believe that no significant increase in evaporation will occur from <br />the lake and that the augmentation as per the decree entered in Case No. 82CW393 will be <br />sufficient and adequate to address the discharge of this additional water to the Henderson Water <br />Ski Lake. <br />Augmentation water comes primarily from a metered, nontributary well (Permit No. <br />64401) that pumps water from the Laramie-Fox Hills aquifer. This well was recently permitted <br />for augmentation and dust control purposes, as well as industrial, commercial, residential, and <br />domestic uses. Its annual production is limited to 15.6 acre-feet per year, of which no more than <br />98 percent may be consumed. The well is also used directly for dust control purposes. <br />The augmentation portion of water from this nontributary well can either be discharged <br />into the Henderson Water Ski Lake, discussed above, with its accretions lagged to the river, or <br />the well can be hooked up via hose to the Brighton 124i1' Avenue pipeline, which discharges <br />directly into the South Platte River. Water from this well can also be trucked to the South Platte <br />River and discharged directly into the river. <br />CONSUMPTIVE USE <br />Water use at the site includes evaporation from a rinse water lagoon and dewatering <br />pond, and water retained in sand and gravel removed from the site. We anticipate that the slurry <br />wall liner will be approved by May 31, 2008, at which time 120th Estates Partners will only need <br />to replace evaporative losses at the site (per meeting with Ms. Joanna Williams and Mr. Kevin <br />Rein, November 2005). The nontributary well water will be used for dust suppression at the site. <br />At the conclusion of mining in September 2008, all the pond water will be discharged directly to <br />the South Plate River or the Henderson Water Ski Lake. <br />Evapor•calive Losses <br />We obtained precipitation data from the Denver Stapleton station; historically the mean <br />'annual precipitation is 15.4 inches. NOAA Technical Report NWS 33 provided the total annual <br />gross evaporation estimate of 45 inches. We utilized the State's monthly percentage distribution <br />of gross evaporation for elevations below 6,500. We computed the effective precipitation as 70% <br />of total precipitation; net evaporation was calculated by subtracting effective precipitation from <br />Martin and Wood Water Consultants, Inc.