WORK PLANS - Laserfiche WebLink

Home Browse Search

OPERABLE UNIT 3 OU 3 Description OU 3 Corresponds to Sub-Recommendation 12.1, which concerns a then-former drum and waste oil storage location. The Phase I identified potential for soil contamination via leaks/spills of petroleum-related compounds. Phase II samples were collected and analyzed for petroleum- related compounds. Petroleum: Existing Data Six soil samples were analyzed for TPH as referenced by TPHd, TPH1o, and TPHueh (EPA 3550, DHS Luft) (Table 0U3-P, soil samples 12-1 through 12-6). These analyses yielded 18 results, of which all are ND except for one TPHueh concentration of 2.1 mg/kg. This concentration is below Industrial Threshold of 440 mg/kg but above the Protection of Groundwater SSL of 1.5 mg/kg. Laboratory reporting limits are not tabulated. Subsequent soil samples were collected below the 5-foot depth of the initial OU 3 TPHueh detection. No hydrocarbons were detected. In addition, OU 3 is about 100 feet up/cross-gradient of OU 2. Impacted groundwater from OU 3 drum storage would likely be detectable in OU 2 downgradient Hydropunch samples. OU 2 Hydropunch samples, however, were ND (Table 0U2-P, hydropunch samples 11-2-HP and 11- 7-HP). Petroleum: Recommendations While OU 3 soils results are largely ND except for a relatively low concentration of TPHueh, there are not enough soil results for OU 3 to strongly indicate a statistical distribution constrained well below reporting limits. Kleinfelder therefore recommends tabulating OU 3 soil reporting limits and evaluating them against Protection of Groundwater SSLs. It is anticipated that this exercise demonstrate that reporting limits typically only marginally exceed Protection of Groundwater SSLs. This should provide the Board the data it needs to demonstrate due diligence in concluding that these data warrant no further action, even if some reporting limits exceed Protection of Groundwater SSLs. Down/cross-gradient Hydropunch data, however, do not indicate petroleum-related contamination. Kleinfelder therefore recommends that evaluation of soil reporting limits be conducted with the context that direct, down/cross-gradient groundwater data indicate that groundwater has been protected. It is anticipated that this exercise will provide the Board the data it needs to demonstrate due diligence with respect to demonstrating that these data warrant no further action. 20173951.001A/SAC17R68420 Page 7 of 26 November 2, 2017 © 2017 Kleinfelder www.kleinfelder.com KLEINFELDER 2882 Prospect Park Dr., Suite 200, Rancho Cordova, CA 95670 p I 916.366-1701 f I 916.366-7013