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95-03-200a GeoSojV, JLC_ d eo 1c Ynves#t afor Nunan Rage a&v YO The next closest water supply well to the site, identified in this investigation, is State Water Supply well No. 39055 (See Appendix 6 for Water Well Drillers Report), which is located 1,100 feet down and cross-gradient from the site and could be 1 hydraulically connected to the perched aquifer beneath the site. Even though the well casing has no perforations and it appears that the well draws water from 210 feet bgs,we don't really know if conduits exist to as shallow as 60 feet bgs where the water level was measured in the well in 1952. Based upon the Water Well 1 Drillers Report for State Water Supply well No. 39055, a conservative estimate of the saturated interval, is from 60 to 210 feet. Constant head permeameter testing was performed on a coarse silty sand sample which was representative of the perched aquifer. Although these types of samples are considered to be disturbed after handling in the laboratory, the result of the testing for horizontal hydraulic conductivity, as reported, is in agreement with typical horizontal hydraulic conductivities for these sands as reported in published literature (Dominic* and Schwartz, Physical and Chemical Hydrrogeology, Page 65, Table 3.2). The conservative values chosen here for comparison show that a coarse 1 sand has a hydraulic conductivity (K) ranging between 0.6 cm/sec to 0.00009 cm/sec. The measured value in the lab from the sample collected at the site is within that range @ 0.0002 cm/sec (See Appendix H foir Constant plead PermGmmWar Testing). According to the Darcy flow equation V=Ki,where "V" is the flow velocity of water, where the hydraulic conductivity K= 0.0002 cm/sec and gradient flow is "i"=0.015, the following holds true; V = 0.0002 cm/sec X 0.015 = 0.000003 cm/sec 0.000003 cunv/sec X 2,830 {t/¢lay/l cm/sec = 0.0085 ffeeg/¢lay Since State Water Supply well No. 39055 is DocWed 1,100 feef from 4he sift, Qhe NV ne it would take to reach the well would be 1,100 feet X 1 day/0.0085 few = 129,411 days 129,411 days X 1 year/365 days 3541/2 years 4o reach the closest potentialh hydraulically connected_water supply well 7ME 1MPACY OF FUMPIMG OF HGa rby Vla tGF SUPPoy Wells on the 4rra nspoot of Djzso�ved Contamin&n�z from the Soto Another scenario to consider is what effect the pumping of State Water Supply well No. 39055 would have on entraining hypothetical dissolved contaminants from the perched groundwater zone beneath the site. Ron of Goehring Pump & Irrigation (209) 727-5548 in ' Lockeford whose company originally installed the well stated that since the well had an 8 inch diameter casing, it could not have had a pumping rate any greater than 35 gallons per minute. Even though Ron stated that the casing was founded in clay all the way to 96 feet bgs, there is no documentation as to the depth of the seal or well construction;so the most conservative approach is followed as evaluated below. Since the pumping rate "Q" of State Water Supply well No. 39055 is no greater ' than 35 gallons/minute. The length and width of the zone of capture and the upgradient stagnation point can be determined by a method of analysis outlined in Fetter,Applied Hydrogeology, 3' Ed., Pages 501-505. 05-03-200? GeoSolvo LLC-Hydrogeologlc lnvestlgatlon for Munan Page 8 of 10