Laserfiche WebLink
Mr. Dave Nettles <br />May 23, 2006 <br />Page 2 <br />RECORDED TEST DATA <br />Recorded daily test data for the first 30 days (April 10 through May 9) is summarized on the <br />attached Table 1. The total volume of water pumped out of the reservoir during the first part of the <br />test was 2,000,500 gallons, which equals approximately 66,683.3 gpd or 46.3 gpm. <br />Approximately 0.06 inches of precipitation were measured by a rain gauge on the site during the 30- <br />day period. Precipitation data recorded at a nearby NOAA weather station (CoAgMet) located six <br />miles south southwest of Fort Lupton) indicates approximately 0.79 inches of precipitation <br />(rain/snow) over the 30-day period. A printout of climatological observations from the CoAgMet <br />station is attached on Table 2. <br />The actual measured precipitation on the site was used for the surface water inflow into the pit. The <br />approximate surface area of the south-cell pit is 54.9 acres. Applying the 0.06 inches of <br />precipitation across this surface area, computes to 89,447 gallons of total inflow during the 30-day <br />period. <br />GRADIENT ACROSS THE SLURRY WALL <br />The water levels from the south cell, paired observation wells indicate the water table just outside <br />the slurry wall has been consistently higher than the water table inside of the slurry wall. The <br />hydraulic gradient across the slurry wall at the end of the initial 30 days of the test ranged from 11 <br />to 16 feet. Hydrographs for the three well pairs are attached. <br />SURFACE WATER <br />Several areas of disconnected pooled water in the bottom of the pit have been monitored. These <br />areas seem to be primarily influenced by precipitation and evaporation. The pools are in isolated <br />low areas and do not drain directly across the surface into the sump. The soils beneath the pooled <br />areas predominately consists of fine grained soils, mainly silty clay. The pooled areas appear to be <br />perched water. <br />The surface areas of the pools have been measured and the sizes of the pools are being monitored <br />during site visits. Pin flags have been placed at the waters edge to observe the rate of decline or <br />increase in the surface area of the pools. Between April 13 and May 11, 2006, the pools receded <br />approximately three feet horizontally. This indicates the recent rate of evaporation has been greater <br />than the rate of surface water inflows from precipitation. Given the current climate trends, the <br />disconnected pools of water may be completely evaporated by the end of the 90-day leak test. <br />The total surface area of the pools during the month of April was estimated to be 129,300 square <br />feet, and for the month of May it was estimated to be 116,108 square feet. The approximate pool <br />areas on the 9th of May are shown on Figure 4. Gross evaporation from the free water surfaces was <br />calculated using the evaporation rates specified in NOAA Technical Report NWS 33 for the region