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Mr. Eric J. Holm <br /> March 26, 1997 <br /> Page 7 <br /> (12) Building No. 18. This building was built and previously operated as a <br /> carpet cleaning company. <br /> Soil gas samples should be collected beneath the building to determine if <br /> solvents, i.e., PCE was ever used by the carpet cleaning company. <br /> (13) The parking lot south of Building 18. DTSC's file indicates that the <br /> areas were used to store used drums in early 1980s'. Therefore, shallow <br /> soil gas samples at 10 feet bgs should be collected in this area to determine <br /> if past operations have contributed to any VOCs contaminations. The soil <br /> gas data can also be used to determine the extent of contamination from <br /> upgradient and east locations. <br /> (14) Along the City's industrial sewer lines. Wastewater generated at the <br /> Site have been discharged into the City's industrial sewer lines. <br /> Therefore, depth-discrete soil gas samples at 10 and/or 20 feet should be <br /> collected along the sewer lines beneath Sacramento Street. Soil gas <br /> samples at deeper depth, i.e., 30 feet may be collected depending on the <br /> results of the shallow soil gas samples. <br /> (15) Outside of any Holz's buildings' doors that access the railroad tracks. <br /> Soil and soil gas samples should be collected outside of any Holz's doors <br /> that access the railroad tracks,to determine if the soil is contaminated with <br /> metals, VOCs, semi-VOCs, and/or TPH. <br /> For your convenience, the above proposed soil gas sampling locations are <br /> furtherplottedin the attached map of Figure 2. Please note that the plotted <br /> sampling locations are preliminary and must be refined based on their <br /> accessibility, and the actual dimension of each building and the Site (Figure 2 is <br /> not a scaled map). Furthermore, DTSC does not require that depth-discrete soil <br /> gas samples at 10, 20 and 30 feet bgs be collected at all sampling locations. The <br /> number of depth-discrete samples may be determined based on the actual field <br /> sampling results, i.e., should sampling results show that the highest contamination <br /> resides at 20 feet bgs,then samples may be collected at 20 feet in lieu of 10 feet <br /> bgs. The spatial distribution of soil gas sampling locations should be based on the <br /> Los Angeles Regional Water Quality Control Board guidance document entitled <br /> "Interim Guidance for Remediation of VOC Impacted Sites" and other document. <br /> Soil gas sampling locations placed approximately 30 to 50 feet apart may be <br /> appropriate for source determination and delineation of the subsurface VOCs <br />