ARCHIVED REPORTS_XR0009515 - Laserfiche WebLink

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i c The San Joaquin EHD office sent correspondence dated October 18, 1993, (EXHIBIT H) to Mr. Lechich stffng that a workplan must be submitted for approval to investigate if the groundwater underlying the site had been contaminated with petroleum hydrocarbon (leaded gasoline) and assist in establishing the lateral and vertical extent of soil i; contamination. The apparent contamination was caused by leakage from one (1) 500 gallon i UST that was located on the property, but was subsequently removed. The tank had been used to store leaded gasoline. Some of the documentation for this site refer to unleaded !� fuel while others stated leaded gasoline. The age of the removed UST was reported to be twenty-eight (28) years, therefore Wm. J. Hunter & Associates (WJH) is assuming that the j tank held leaded gasoline. M In December, 1993, Wm. J. Hunter & Associates prepared a workplan, EXHIBIT L, for the boring and construction of three (3) monitoring wells to investigate if the groundwater . � was contaminated with petroleum hydrocarbons and help in determining the extent of soil contamination at the site. The workplan was submitted to the San Joaquin County PHS, i Environmental Health Division on December 30, 1993, for review and approval was given to commence with.the program. - I f MOST RECENT WORK k ' SOIL BORINGS FOR MONITOR WELLS i ;i BORINGS. a j f The permit for the drilling of the monitoring wells was issued by the San Joaquin County '- I Public Health Services, Environmental Health Division, EXHIBIT M, and the City of Stockton granted an encroachment permit and revocable permit, EXHIBIT N, for the monitoring well that was to be installed in the sidewalk adjacent to the northeast side of the building, I On February 28, 1994, Spectrum Drilling moved in a properly licensed auger rig and using j clean 101/x" OD hollow stem augers advanced two (2) borings MWI and MW2, PLATE �f VIIIa, and EXHIBIT O, to a total depth of thirty (30) feet below ground level, PLATE IX. Prior to starting the borings, a diamond bladed power saw was used to cut out a square of 6" thick concrete. Using a California modified Splitspoon Sampler fitted with three (3) 2" x 6" brass tubes, soil samples were taken at five (5) foot intervals beginning at ten (10) feet ' below ground level. In boring MW1, soil samples were collected at 101/2-11 (MW1-1), 151/2-16 (MW1-2), and 21-211/2 (MW1-3). The soil sample identified as MW1-2 had a f f9 questionable petroleum odor, otherwise there was no detected odor or visible appearance of petroleum contamination in this boring. The top of the water table was encountered at ! twenty (20) feet below the ground surface and the boring was advanced ahead to a depth of thirty (30) feet. In boring MW2, soil samples were collected at 101/z-11 (MW2-1), 151/2-16 (MW2-2), 201/2- , E `j 21 (MW2-3), and 251/2-26 (MW2-4). Soil sample MW2-1 had a questionable petroleum f 3 odor; sample MW2-2 had a strong petroleum odor and appeared wet with product; sample MW2-3 also had a strong gasoline odor and a rainbow sheen was seen on water running 4 E I+ � ij i