ARCHIVED REPORTS_SECOND SEMIANNUAL AND 2011 ANNUAL GROUNDWATER MONITORING REPORT

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r 3.ANNUAL REPORT FOR 2011 I the active remediation systems,as documented in the 3-Year Evaluation of the Bioremediation Pilot Study(CH2M HILL,2007a). No redundancies have been identified regarding the wells that are sampled and analytes r that are analyzed in the lab. Current MRP No. R5-2007-0831 was developed to be streamlined and monitor current Site conditions with MNA and phytoremediation as remedies.This MRP eliminated most of the parameters added in the previous MRP to J monitor the bioremediation pilot test,eliminated unnecessary monitoring wells and parameters,allowed for the destruction of unnecessary monitoring wells, and allowed for the destruction of the soil vapor extraction well system. •1 However,as further described in Section 3.4,a more efficient method of using HydraSleeve samplers was compared to the current"standard" purge method. The comparison was J evaluated during the second semiannual 2011 monitoring event and is recommended to be implemented beginning with the next semiannual monitoring event in lieu of the standard purge method, upon concurrence of the RWQCB. 3.4 Comparison of Standard Purge Samples versus HydraSleeve Samples On October 29,2010,SFPP and CH2M HILL proposed to the RWQCB the use of a HydraSleeve sampling device (hydrasleeve.com) to collect the semiannual groundwater samples in place of the current sampling methodology at the Holt Release Site. The current - methodology entails purging the wells using a portable Grundfos pump and then collecting wo the samples using disposable bailers. In some instances,the current methodology entails using a disposable bailer to both purge and sample a well if purging with the Grundfos pump is not practicable. Switching from the current pump/bail methodology to using a HydraSleeve sampling device will have several advantages,including the following: • HydraSleeve may result in samples that are more representative of the formation. • HydraSleeve will result in less investigation-derived waste (IDW) water generation. • HydraSleeve will result in more efficient sample collection. SFPP proposed and gained RWQCB approval on implementing the following steps prior to - switching to using only the HydraSleeve methodology to assure that the new sampling J methodology results in samples are comparable to the current methodology: • During the March 2011 semiannual sampling event,SFPP set HydraSleeve sampling devises in 50 percent(7 of 14) of the wells that capture the range of conditions at the Site (low-to-high concentrations,coarse versus fine-grained lithology, shallow versus deep). • During the following semiannual sampling event on September 1,2011,SFPP collected groundwater samples from the HydraSleeve samplers (7 of 14 wells) and then immediately collect samples from all 14 wells using the standard pump/bail I methodology. 3.4 ES1024111033035C0ILW3521.DOCXI112970003 r