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United Parcel Service <br /> March 16, 1992 <br /> Page 3 <br /> predominately of a mixture of brown clay and silt; the waste oil tank soils appear to <br /> consist of dark brown-black clays. <br /> Three samples were obtained of the soil removed from the gasoline tank excavation: <br /> one from the initially excavated soil and two from the overexcavated soil. The initial <br /> sample was analyzed for TPH as gasoline, BTEX, total lead, organic lead and ethylene <br /> dibromide (EDB). The results from the initial sample testing revealed 37 ppm gasoline, <br /> slight levels of all the BTEX substances, no EDB, no organic lead and 16 ppm total <br /> lead. The SJCEH established local background level for lead is 13 ppm. The two <br /> samples obtained from soil removed during over-excavation of the gasoline tank <br /> excavation were analyzed for only gasoline and BTEX; none was detected in either <br /> sample. <br /> The stockpiled soil from the waste oil tank excavation does not appear to have been <br /> sampled. SJCEH stockpile sampling protocol requires one discrete sample per 50 <br /> cubic yards of soil or two discrete samples per 50 cubic yards which may be <br /> composited into one sample at the chemical laboratory. <br /> CURRENT WORK <br /> GENERAL <br /> Based on SJCEH requirements and your requests, the following work elements are <br /> needed: (1 ) contaminated soil removal and deeper sampling within the waste oil tank <br /> excavation; (2) backfill of the waste oil tank excavation; (3) stockpile characterization <br /> sampling and analysis; (4) development of off-site remediation/disposal alternatives <br /> for stockpiled soil; and, (5) the preparation of a summary report for UPS, SJCEH and <br /> remediation/disposal contractor review. <br /> Our proposed work elements are described separately below. <br /> t <br /> #1 — EXCAVATION AND SAMPLING <br /> Because the existing excavation is so near the shallow building foundations, it is our <br /> opinion that the excavation must be backfilled to maintain structural stability of the <br /> soil and then be sampled via drill-rig. Saturated uncontrolled soils will need to be <br /> removed prior to structural backfill placement. Removal of soft soil and any additional <br /> excavation will be precarious and must proceed with extreme caution. An engineer <br /> from our staff, experienced in both geotechnical and environmental engineering, would <br /> be on-site during the excavation work. A bench mark would be established and <br /> survey control targets would be located on the building near the excavation for <br /> settlement monitoring. Our engineer, working together with on-site SJCEH personnel, <br /> would determine actual limits of the excavation work. A narrow backhoe bucket <br /> p , would be used so that relatively delicate excavation work could be performed so as <br /> ■ Geotechnical <br /> LAIL <br /> CD <br /> C <br /> Ip r <br />