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0 <br />Percent finer that 5 microns 30% <br />During construction of the final cover over the north and northeast slopes, the constructed <br />soils were found to be generally consistent with the requirements of the CQA Plan. Of <br />particular significance, the saturated hydraulic conductivity exceeded the maximum <br />requirement and varied from 1 x 10-6 cm/s to 4 x 10-8 cm/s with geometric mean of about <br />3.2 x 10.7 cm/s. This compares well with testing completed for the initial borrow <br />evaluation which yielded a geometric mean saturated hydraulic conductivity of 2.0 x 10 <br />cm/s. In addition, it is our understanding that the compaction and moisture content testing <br />completed during construction yielded results consistent with the original CQA Plan. <br />A minor deviation from the CQA standard was identified for the percent passing the #200 <br />Sieve in that, while the average for these tests yielded the recommended 70% passing, <br />several individual tests results did not. Somewhat more consistant deviations are noted <br />for the percent finer than 5 microns which yielded an average of only about 22% rather <br />that the recommended 30%. In fact, a majority of the tests yielded less than 30%. <br />DISCUSSION <br />While the as -built characteristics of the final cover system constructed over the north and <br />northeast slopes of the Forward Landfill deviate slightly from the recommendations of the <br />site Final Closure Plan and associated Construction Quality Assurance Plan, these <br />deviations are believed to be minor. Since the saturated hydraulic conductivity <br />significantly exceeds the minimum requirements of the project, the slight deviations in <br />grain -size distribution are considered even less significant and it is concluded that the as - <br />built final cover still satisfies all 27 CCR criteria for closure of an unlined Class III <br />landfill. <br />With regard to extrapolation of the as -built data in support of future implementation of a <br />similar final cover system as an alternative to prescriptive standards, GLA is completing <br />supplemental soil suction analyses on the as -built soils and intends to analyze the long- <br />term performance of the as -built system as soon as that data becomes available. It is <br />believed that the slight reduction in the fines content will not significantly affect the <br />modeling results and may, in fact, yield a benefit since a reduced clay content should <br />produce a system that is less susceptible to desiccation. <br />Regardless of the minor deviations identified in construction and the modeling results <br />that will be derived from the as -built soils analyses, Forward still anticipates installation <br />of the final cover performance monitoring systems late in the Winter of 2006. Assuming a <br />twice/month downloading event, GLA will evaluate the downloaded data from each <br />monitoring unit on a quarterly basis to incorporate the data into a running summary. This <br />task would be repeated throughout the two-year monitoring period. At the end of the each <br />year of monitoring, a report will be prepared to summarize the data received from the <br />instruments, to identify significant identifiable trends, and to present conclusions drawn <br />with regard to the performance of the system as a whole. This report will include a <br />CA2005.0082 1/06/06, <br />