SITE INFORMATION AND CORRESPONDENCE

Home Browse Search

Project No.013-10141 Page No. 7 may or may not be required, however, depending on site-specific conditions and considerations. As stated by the RWQCB, the ESL document may be especially beneficial for use at sites with limited impacts, where the preparation of a formal environmental assessment may not be warranted or feasible due to time and cost constraints. In addition, some constituents are not addressed under the RWQCB ESL,therefore,USEPA Regional Screening Levels were utilized. A discussion of the results of the LSI is summarized below: Where applicable, the RWQCB ESLs and ESEPA RSLs for shallow soil in commercial/industrial settings were used to evaluate soil for potential environmental concern or further evaluation. • The soil sample collected adjacent to the location of the inactive equipment wash drain located within the southern portion of the site building(B-1@5')was reported as ND for TPH-g, TPH-d, and VOCs. Soil samples collected from the locations of the inactive clarifier located within the southern portion of the site building (B-1@10' and B-2@10') were reported with concentrations of TPH-g that are above the RWQCB ESL of 180 mg/kg for gasoline petroleum hydrocarbons; however, TPH-d was reported as ND for both samples. Concentrations of VOCs reported above their respective ESLs included the following: 1,2-Dichlorobenzene (ESL of 1.6 mg/kg), 1,4- Dichlorobenzene (ESL of 1.8 mg/kg), Napthalene (ESL of 2.8 mg/kg), and 1,1,2,2- Tetrachloroethane (ESL of 0.60 mg/kg). Therefore, it appears that concentrations of TPH-g and various detected VOCs,including chlorinated solvents above their respective RWQCB ESLs and RSLs,were detected in the subsurface soils beneath the inactive clarifier. • Soil samples collected adjacent to the locations of the active clarifier, equipment wash rack and drain located within the northern portion of the site building(B-4@ 10',B-5@10', and B-6,B-7, B-8, B-9, and B-10@3') were reported as ND for TPH-g, TPH-d, TEPH, and LUFT metals, except for less than significant concentrations of 13 mg/kg of TPH-g detected in sample B- 4@10',which are below the RWQCB ESL of 180 mg/kg for TPH-g. • Concentrations of heavy metals detected in the soil samples collected adjacent to the clarifiers, drains, and wash rack were below their respective ESLs and RSLs, and are therefore not considered to pose a significant threat to human health and/or the environment within the areas where samples were collected and analyzed. 8.0 CONCLUSIONS Based on the results of this investigation, it appears that subsurface impacts from hazardous materials/wastes have occurred in the area of the on-site inactive equipment wash clarifier investigated by Krazan. Based on the analytical results, concentrations of TPH-g and various detected VOCs including the chlorinated solvent Tetrachloroethane above their respective RWQCB ESLs and RSLs, were detected in the subsurface soils beneath the inactive clarifier. The vertical extent of impact from TPH-g and VOCs beneath the inactive clarifier is currently unknown; however, deeper samples (B-1 and B-2@15 and 20 feet bgs)were collected by Krazan at the time of the field investigation for this assessment and placed on KRAZAN&ASSOCIATES,INC. Conducting Assessments Nationwide 1310141 WW R®tats LSI DRAFr.doc