ARCHIVED REPORTS XR0000224 - Laserfiche WebLink

Home Browse Search

E_ C 22 Groundwater Depth Sounding, Purging and Sampling Twelve monitoring wells were sounded by SECOR personnel on September 20, 2005 Depth-to-water In each of the wells was measured to the nearest 0 01 foot below top of casing (TOC) The water-level Indicator was decontaminated with de-ionized water prior to each measurement Well construction specifications, sample collection data, and groundwater elevations are summarized in Table 1 Groundwater elevations were used to create a groundwater elevation contour map and to calculate groundwater flow direction and gradient (Figure 4) Groundwater was found to flow to the northeast at a hydraulic gradient of approximately 0 0043 ft/ft Monitoring wells were purged prior to sampling using a submersible pump and dedicated tubing Each well was purged of at least three well volumes or until measurements of pH, temperature, and conductivity stabilized To minimize the potential for cross-contamination, the order of purging and sampling was wells MW-11, MW-20, MW-9, MW-16, MW-19, MW- 25, MW-24, MW-13, MW-12, VM-1, VM-2, and MW-14A Measurements of dissolved oxygen (DO) using a down-well probe were collected and recorded on water sample field data sheets prior to purging Measurements of ferrous Iron and oxygen-reduction potential (ORP) were collected and recorded after purging Field data sheets are Included as Appendix B Groundwater samples were collected on September 22, October 11, and October 22, 2005, with disposable bailers Samples were retaken due to loss and/or damage of original samples taken on September 22, 2005 After collection, all samples were Immediately placed on Ice for storage and shipment to the laboratory Samples were transported under chain-of-custody (COC) procedures to the state-certified laboratory for analysis Laboratory analytical reports and COC forms are Included In Appendix A 23 Quality Assurance/Quality Control Measures Laboratory quality assurance/quality control (QAIQC) for groundwater samples Included analysis of one method blank, one matrix spike/duplicate, and a laboratory control sample/duplicate for each batch of samples sent to the laboratory One equipment blank and one trip blank were collected on September 20, 2005, but were lost during transport and not re-sampled this quarter Equipment and trip blanks will be collected in future sampling events 11CALTRANSIstockton-Shop 101GW Monitonngl3rd Qtr 20051Q3 fly OM&M_Final doc November 29 2005 Project No 940T 43148 00 4 SECOR International Incorporated