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1 1386 E SEAMEr"i- STREET <br /> WOODLAND CA 95695 9603 <br /> 662 0273 <br /> �i WESTERN GEO-ENGINEERS (Ax ) 6)6622--455441 <br /> CALIF CONTRACTOR 0 513857 A COnOORATION �3 8) <br /> REGISTERED GEOLOGIC 15 <br /> July 13, 1990 RECEIVED <br /> Ms. Eleanor Ratliff, RENS <br /> San Joaquin Coun-.y Environmental Health JUL f 6 ,990 <br /> PO sox 2009 E, - RONMENTAL HEAL i H <br /> Stockton, CA 95201 PERMIT/SERVICES <br /> i <br /> RE: Addendum to work plan to place two onsite monitor wells to <br /> investigate the extent of ground water contamination beneath � <br /> Regal Station 684, 1448 N. E1 Dorado Street, Stockton, California. <br /> Dear Ms. Ratliff: i <br /> To further delineate the lateral extent of ground water <br /> contamination beneath the above mentioned site, Western Geo- <br /> Engineers (WEGE) will use Hogate Drilling (C-57 license #401530) . <br /> WEGE is a Registered Geologist/Environmental Consulting Co. and as <br /> also a licensed C57 drilling contractor. This site is bung <br /> assessed under Calif. Reg. Geol. # 3037 and WEGE's C-57 license <br /> #513857. <br /> Figure 3 and the enclosed permits show the locations of proposed <br /> monitor wells MW-5 and MW-6. We are still negotiating with nearby <br /> land owners to gain permission for the placement of monitor well <br /> E <br /> MW-7. <br /> DRILLING AND WELL CONSTRUCTION <br /> Monitor well MW-5 will be drilled using l0" hollow stem augers at <br /> approximately a 20- angle to sample the ground water beneath the <br /> store and south of the excavation. Ground water is presently <br /> found between 47' to 521 below the surface. High ground water for <br /> = the last 10 years, as recorded by San Joaquin County Flood Control <br /> and Water Conservation District for this area was 40 feet below <br /> the surface in 1953 and ranges between 45' to 75' below the <br /> surface between 1979 to 1989. At a 20" boring angle the measured <br /> depth of the hole will be approximately 64' with a drift <br /> (horizontal deviation) of approximately 22' to the south, under <br /> the building, see figure 3. <br /> The well will be constructed using $ch. 40 F480 4" PVC pipe with <br /> threaded joints. The screen section (0.010" machine slotted) will <br /> be from 34' to 64' measured depth (true vertical depth of 32' to <br /> 600 below the surface) . The sand envelope (gravel pack) will be <br /> from total depth 64* to 26.5 feet measured depth (true vertical <br /> depths of 60'-25' feet below the surface) . The sand will be of <br /> clean #2/12 monterey sand. A 3' thick hydrated bentonite seal <br /> will then be placed on top of the sand pack with a neat cement/5% <br /> bentonite seal from surface to the top of the bentonite. A water <br /> tight security lockable traffic box will be placed at grade over <br /> -- the well with a 3' x 3' reinforced concrete pad, see Figure 4 for <br />