ARCHIVED REPORTS_XR0011635 - Laserfiche WebLink

Home Browse Search

Y y'. s. Groundwater Monitoring Well Installation and Ozone Microsparge System Installation and Startup Report— ConocoPhillips(76)Service Station No. 11195,Lathrop,California May 20,2003 augers. Borings SP-1 through SP-15 were completed as microsparge points with the installation of 2-inch diameter spargers attached to 3/-inch diameter blank schedule 80 PVC casing placed through the hollow-stern augers. The spargers are composed of 30-inch long microporous plastic. For the monitoring wells, Lonestar # 3 sand was installed in the annular space from the bottom of the boring to approximately 1 foot above the top of the well screen. For the sparge points, Lonestar # 2/16 sand was installed in the annular space from the bottom of boring to between 1 and 2 feet above the top of the sparge point. The remainder of the annular space in each boring was then sealed with hydrated bentonite followed by neat cement to a depth of approximately 1-foot bgs. A steel, water-resistant, traffic-rated well box was set into the ground around each wellhead with concrete. Mr. Michael J. Infurna of the San Joaquin County PHS-EHD was on site to observe the grouting procedures. Monitoring well and sparge point construction details are presented on the boring logs in Appendix B. Drill cuttings were placed on and covered with plastic sheeting, and a 4-part composite soil sample was collected and submitted to the laboratory for analysis as required by the landfill. Disposal of the soil is described below in Section 6.4. 5.2 Monitoring Well Development and Sampling s - On February 13", 2003, static groundwater levels were measured in the newly installed and existing wells. Each well was checked for the presence of separate-phase hydrocarbons. Separate-phase hydrocarbons were not observed in any of the wells. Static water level data and groundwater elevations are summarized in Table 1. After the static water levels were measured, the new monitoring wells (MW-18 through MW-21) were developed by GR personnel using a 2-inch diameter stainless steel bailer and submersible pump. Copies of the GR Well Development and Groundwater Sampling Field Data Sheets are included in Appendix C. A Potentiometric Map is included with this report as Figure 3. After development, groundwater samples were collected from the monitoring wells as specified by GR's Field Methods and Procedures (Appendix A). Water purged during well development and sampling was transported to the Tosco Refinery in Rodeo, California, for disposal. i 5.3 Wellhead Survev j Following installation, the well casing elevations and horizontal coordinates of the new wells were surveyed by Virgil Chavez Land Surveying of Vallejo, California (Licensed California Land Surveyor No. 6323). Top of casing (TOC) elevations were measured relative to MSL, and the horizontal locations of the wells were measured using the Global Positioning System (GPS). Well casing elevation data are presented in Table 1. A copy of the surveyor's report is included in 1' Appendix D. 140193.14-2 6 F