ARCHIVED REPORTS_XR0002152 - Laserfiche WebLink

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Clay on 4 URf I\11F\t 11 [fl\til IIAN I • _ EPA Method 5030/8015-8020 for gasoline fuel and the volatile hydrocarbons, benzene, toluene, ethylbenzene, and xylene • EPA Method 4181 for total recoverable hydrocarbons All samples were transported to Clayton's laboratory under chain-of-custody. This form, along with copies of analytical results are in Appendix E. 4.2 SOIL SAMPLE ANALYSES 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 hmits, as shown in the laboratory report (Appendix E) Table 2 shows that the LUFT manual guidelines do not apply to the first two chemical constituents listed due to the shallow groundwater (approximately 8 to 12 feet bgs) Analytical results revealed a concentration of 770 mg/kg total recoverable hydrocarbons from soil sample MW-313 Qu 4 feet. This concentration is most likely due to oil and grease Although regulatory action levels are not set for oil and grease,when concentrations exceed 100 parts per million (ppm) the RWQCB's Recommondation§ for EvaluaUgon and Investigation of UffA requires a sotl/groundwater investigation The concentrations of total recoverable hydrocarbons found in the soil at 4 feet in MW-3B puts the s,te into the RWQCB's "Case 1" category requmng,a soil/groundwater -, 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 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. 50 Concentrations of hydrocarbons in the water samples collected from MW-1, MW-2 and MW-3B were below detection limits. Therefore, Clayton recommends that semi- annual groundwater monitoring be conducted of momtonng well MW-3B at the site for one year to momtor any changes. -. The newly installed monitoring well MW-313 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 ry boring program to define the horizontal and vertical extant of contamination may be required by the SICPHS along the abandoned leach line. -4- 3249-.V