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3.0 HYDROLOGIC ASSESSMENT <br />• :az-r:rn.•.:;:s:.-.;.~:.~:r;•.x.:~:men:•.:~:~:~.,;'«as:~:an::x:xr:yea:~;:::x.:f:c'.M;ruxx~:;~.:r:a;:~'rr,':eryn:xa:a;rs::aa.::;~~x~,cma:xcc:,s::xxx~ea.~a~aas'ax~we+.'~.xcs'c~tux~,:.~~eaa.•.~arms <br />3.1 PROCEDURES <br />The locations of the monitor wells were identified by Powderhom based upon accessibility and <br />to expedite sampling for future monitoring. <br />The UTL and N-Decline monitoring wells consist of 95 feet of two-inch diameter, flush joint, <br />0.020 inch machine slotted PVC well screen. Blank casing of similar construction was added to <br />each well to reach just above the surface grade. The bottom of each well was fitted with atwo- <br />inch diameter PVC bottom cap, and the top of each casing was fitted with a locking gripper cap. <br />The annular space of each well was filled with silica sand to a level of two feet above the screened <br />interval. Bentonite was emplaced above the sand to prevent surface infiltration. Concrete grout <br />was then added to reach near surface grade where a 4-inch diameter stand-up box was emplaced <br />to complete each well. Development of the monitor wells was accomplished by air lifting each <br />well for a minimum of 45 minutes. Well completion logs are included in Appendix II. The RSN <br />and RSS wells were competed as open boreholes. Due to refusal of the 3.25-inch bit, a 1.5-inch <br />bit was utilized. As a result, the boreholes could not be cased. The RSS well was developed by <br />removing three well volumes of water by surging and purging of the borehole. The RSN well <br />continues to flow over the collar at approximately 0.25 gallons per minute and was not developed. <br />• 3.2 GROUNDWATER MONITORING <br />All monitor wells were measured for depth to water (DTW) on June 30, 1997. Depth to water <br />was measured from the top, north side of the well casing. Groundwater elevations were calculated <br />using the measured groundwater elevation data and the surveyed well casing elevations. <br />The groundwater level measurements collected on June 30, 1997 are included in Table 1. One <br />of the wells (RSN Well) was artesian and the other wells showed signs of being under pressure <br />with slowly rising static head. Once the wells had equilibrated, depth to water ranged from <br />approximately 8 feet above grade in the RSN well to 56.5 feet below grade in the N-decline well. <br />The groundwater gradient determined during the investigation was to the northwest. An elevation <br />groundwater contour map is depicted as Figure 2. <br />Table 1 <br />Water Level Measurements <br />- - Groundwater <br />Well Date Casine Elevation Deoth to Water' Elevation <br />UTL Well 06/30/97 4,760.20 19.00 4741.2 <br />N-Decline Well 06/30/97 4,804.1 56.5 4747.6 <br />RSS Well 06/30/97 4,950 7.30 4942.70 <br />RSN Well 06/30/97 4,540 -8.0* 4548.0 <br />' Measured from top of well casing. + Estimated after adding a pressure gauge. <br />• <br />r~ <br />r2.593\l\Sepmmber 16, 1997 <br />