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STATE OF CALIFORNIA GEORGE DEUKMEJIAN, Governor <br />CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD - <br />CENTRAL VALLEY REGION .� <br />3443 ROUTIER ROAD <br />SACRAMENTO, CA 95827-3098 <br />20 September 1989 <br />Mr. Greg Basso <br />Forward Inc. <br />P. n. Box 6336 <br />Stockton, CA 95206 <br />FORWARD LANDFILL, SAN JOAQUIN COUNTY (CASE NO. 2209) <br />We have reviewed the September 1989 design report for <br />expansion of waste management unit (WMU) D at the Forward <br />facility. The expansion area, known as Pit D89, is regulated <br />under waste discharge requirements (WDRs) Order No. 89-148 <br />as a Class III landfill. The proposed design satisfies the <br />requirements of Forward's WDRs and Subchapter 15, Title 23, <br />California Code of Regulations (Subchapter 15) except for <br />vadose zone monitoring, as discussed below. <br />No vadose zone monitoring is proposed under the temporary <br />leachate sump and riser at the northern boundary of Pit D89. <br />Vadose zone monitoring needs to be provided under this area <br />until expansion of the pit makes monitoring at this location <br />impractical. <br />With respect to the drainage calculations provided in the <br />design report, we question the use of 10-8 cm/sec for <br />saturated hydraulic conductivity in the HELP model to <br />estimate <br />leak-age through <br />Lrv:g♦ the CiFy liiEr-- . in addition, we <br />question the use of 1974 to 1977 precipitation data in the <br />HELP calculations in light of the drought which occurred <br />during this time. Results from the HELP model, if correct, <br />can provide useful boundary conditions in estimating leakage <br />from the unit and "designated levels" for waste discharged to <br />this WMU. You need to provide rationale for use of the <br />permeability and precipitation data in the HELP calculations. <br />In addition, you need to provided "designated levels" if you <br />intend to accept waste other than the typical "nonhazardous <br />solid waste" and "inert waste" described in the enclosed <br />letter (with attachments). <br />11 <br />