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protect site ground water. Treatment by a proprietary process offered by Cunningham Davis <br /> Environmental, Inc. (CDE) was proposed. Treated soil would be sampled and analyzed for <br /> soluble lead using the WET with a citrate leach. The remediation goal for treated soil was <br /> 5.0 mg/L (California soluble threshold limit concentration [STLC] for lead). In addition, <br /> treated soil would be sampled and analyzed for total lead to document that the average <br /> concentration was less than 1,000 mg/kg (California total threshold limit concentration <br /> (TTLC]). All treated soil that met the above criteria would be placed in the bottom portion <br /> of the excavated areas and compacted. Clean, geotechnically suitable soil would be <br /> imported, placed, and compacted over the treated soil. To further document lack of impact <br /> to site ground water, four additional monitoring wells would be installed, developed, and <br /> surveyed. Ground water flow direction would be assessed and samples would be collected <br /> from all site monitoring wells (six) and analyzed for dissolved lead. <br /> The modified soil remediation program was approved by the Regional Board in a letter to <br /> SPTCo dated February 29, 1996. Additional requirements stated in the approval letter were <br /> that treated soil must be sampled and analyzed for soluble lead using the WET with a <br /> deionized water leach and must meet an acceptance criteria of 0.1 mg/L. It was also stated <br /> that the monitoring wells are to be sampled and analyzed for dissolved lead for a minimum <br /> of three quarters. <br /> Prior to implementation of the modified soil remediation program, an aerial survey of the site <br /> was conducted and a detailed topographic map of the site prepared to document the location <br /> and extent of excavated areas. This detailed mapping program was undertaken so that areas <br /> already excavated could be accurately relocated should there be a reason to continue <br /> excavation of lead-impacted soil at some future date. <br /> Q am was initiated n April 29 1996. Soil screening, <br /> The modified soil remedtatton pro�r s o p <br /> treatment, confirmation sampling, and backfilling operations continued until June 14, 1996. <br /> 369-002.rpd08-09-96/u/keydatalold[racy/reporu/rp[002 4 <br /> TerraNext <br />