ARCHIVED REPORTS XR0006092 - Laserfiche WebLink

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Recovery well RIB was installed using 10 inch hollow stem augers to drill into the second water zone (B Zone) To verify that no underground utilities would be compromised by the drilling, the first 5 feet were hand augered Once the five foot depth was reached, 10 inch hollow stem augers were used to drill the boring to the 20 foot depth From the 20 foot depth to top of B Zone sand, the boring was continuously sampled in two foot intervals to determine the exact depth the sandy interval was encountered (top of water) Once the top of sand was determined the boring was drilled to the 24 foot depth with the 10 inch hollow stem augers and then continuously sampled in two foot intervals to determine the depth to the top of clay (B aquitard) Once the top of clay was encountered the boring was drilled to that depth with the 10 inch hollow stem augers F480 4 inch diameter Sch 40 PVC 0 02 inch slotted screen with a 4 inch length bottom cap was placed across from the B Zone sand (21 to 29feet bts) through the augers and 4 inch diameter sch 40 PVC threaded pipe was attached to the screen and brought to surface #3 sand was then slowly placed between the 4 inch PVC pipe and the augers to 20 feet bts as the augers were staged out of the hole Bentonite pellets were then placed on top of the sand (18 to 20 feet bts) and hydrated with clean city of Stockton tap water An 8 inch diameter traffic rated traffic box was then set in a 24 inch diameter concrete pad in the asphalt street surface approximately 114 inch above asphalt grade with the finished concrete making a smooth transition between the top of the traffic box and the asphalt surface Once all the wells were set (MW6A-B, MW7A-B and RIA-B) the neat cement sanitary • seal was placed, tremied, from the top of the hydrated bentonite to withirb 3 inches from the top of casings All displaced formation waters were collected and placed into 55 gallon drums The neat cement sanitary seal placement was under the supervision of Mr Michael Infurna of San Joaquin County Health COLLECTION AND CERTIFIED ANALYSIS OF SOIL SAMPLES To fill in a data gaps soil samples were obtained from 12, 29 and 30 feet bts of RIB, 28 feet bts of MW6B and 13 feet bts of MW7B The 12 and 13 foot depth samples represent the top of the A Zone saturated area and the 28, 29 and 30 foot depth samples represent vertical extent at the base of the B Zone Samples were obtained by driving I inch diameter by 6 inch length stainless steel tubes into the centers of the 2 inch diameter by 2 feet long cored interval The tube ends were immediately sealed with plastic end caps The sample sleeve was then labeled and placed on ice for Chain of Custody delivery to the contracted DHS certified laboratory, see Appendix E Methods QaIQC The samples were delivered with accompanying chain of custody documentation to KIFF Analytical LLC (DHS certified #2236) KIFF analyzed the soil for concentrations of TPH-G, BTEX, and the 7 Oxygenants using EPA method 8260B 10 Sanchez 2nd QM 2001