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.. AT k b Clayton ENVIRONMENTAL CONSULTANT5 EPA Method 5030/8015-8020, for gasoline fuel and the volatile hydrocarbons, benzene, toluene, ethylbenzene, and xylene. • EPA Method 418.1 for total recoverable hydrocarbons All samples were transported to Clayton's laboratory under chain-of-custody. This .,, farm, along with copies of analytical results are in Appendix E. 4.2 SOIL SAMPLE ANALYSES i `t The results of the laboratory analyses of the soil samples are summarized in Table 2. All other compounds for which analyses were conducted were below analytical detection limits, as shown in the Iaboratory report (_Appendix E). ;;..a Table 2 shows that the LLJFI'manual guidelines do not apply to the first two chemical constituents listed due to the shallow groundwater(appro)dmately 8 to 12 feet bgs). Analytical results revealed a concentration of 770 mg/kg total recoverable ,-. hydrocarbons from soil sample MW-3B @ 4 feet. This concentration is most likely r., due to oil and grease. Although regulatory action levels are not set for oil and grease,when concentrations E exceed 100 parts per million (ppm) the RWQCB's Recommendations for the �t Evaluation and Investi atioD of USTsrequires a softroundwater investigation. The concentrations of total recoverable hydrocarbons Found in the soil at 4 feet in MW=3B ";"" puts.the site into the RWQCB's "Case 1" category requiring a soil0groundwater . investigation. This requirement is satisfied by the current study. The RWQCB developed the 100 ppm level to help prioritize cases, not as a cleanup level. The level of cleanup is determined by assessing the potential for soil contamination to impact groundwater. .4.3 GROUNDWATER ANALYSES f Groundwater samples were collected from monitoring wells (MW-1, MW-2, and MW- 3B). Analytical results revealed gasoline, BTEX, and total recoverable hydrocarbons were below detection levels in all three wells. The results of the laboratory analyses are in Appendix E. r t i 5.0 CQNrJM NS , t z j . Concentrations of hydxacarbons.in the°.ater.samples collected from MW-Ij MW-2. - and MW-3B were below detection hmi.s. Therefore, Clayton recommends that semi- annual groundwater monitoring be conducted of monitoring well MW-3B at the site for one year to monitor any changes, The newly installed monitoring well MW-3B detected 770 mg/kg total recoverable hydrocarbons in soils at 4 feet bgs, and 20 mg/kg at 9.feet bgs. A limited shallow soil . boring program to define the horizontal and vertical extant of contamination may be Lj ; required by the SJCPI-IS along the abandoned leach line.' r S � -4- 32fA9-Imp I r� j i - iiw' 3 f aV F ti 06-pips Hl R1 I IN