Laserfiche WebLink
T r <br /> i <br /> 1 J <br /> ' 02 March 2004 <br /> AGE-NC Project No 95-0144 <br /> ' Page 4 of 5 <br /> i <br /> i <br /> Analytical results for the fourth quarter 2003 monitoring event are summarized on Tables 2 and 3 <br /> .Analytical results of recent and historical ground water samples are summarized on Tables 4 and 5 <br /> The laboratory report (MAI Lab IDs 0310527-001 through 0310527-008) and chain-of-custody <br /> forms are Included in Appendix B <br /> 4 0, SUMMARY/CONCLUSIONS <br /> Based upon data collected during the ground water monitoring event, AGE concludes <br /> - The average ground water elevation at the site was 9 0 feet below MSL Ground water <br /> remained above the screened Interval In five of the shallow-screened wells sampled during <br /> ' the fourth quarter of 2003 <br /> Ground water elevations in deep-screened wells,completed in the Lower Water Zone,were <br /> between 0 55 to 1 73 feet lower than in shallow-screened wells,completed within the Upper <br /> ' Water Zone <br /> - Ground water was Inferred to flow towards the north-northeast in the Upper Water Zone,but <br /> , . was Inferred to flow radially towards the west-southwest In the Lower Water Zane ' " <br /> i <br /> The most Impacted ground water appears to be limited to the area surrounding the former <br /> UST No 8 (Figure 4) TPH-g and TPH-d were detected in ground water samples collected, <br /> ' from monitoring wells MW-21 A,MW-21B and MW-20A at concentrations as high as 3,300 <br /> gg/l and 5,700 gg/l, respectively, in well MW-21A Various BTEX constituents were also <br /> detected In samples MW-21A, MW-21B and MW-20A The detected concentration of <br /> ' benzene in MW-21A exceeds the DHS' Maximum Contaminant Level for drinking water <br /> Fuel oxygenate MTBE was not detected above laboratory reporting limits (EPA Method <br /> ' 8021B) in the ground water samples collected during the fourth quarter 2003 <br /> AGE believes that through an oversight, nested monitoring well MW-21A/B were <br /> inadvertently sampled and labeled as MW-19A/B The concentrations of petroleum <br /> hydrocarbons detected in nested well MW-19A/B appear to be anomalous <br /> r , <br /> 5,0, RECOMMENDATIONS <br /> Itis AGE's understanding that the monitoring well network at 423 North Madison Street,Stockton, <br /> California will be abandoned during first quarter 2004 as part of redevelopment activities at the site <br /> ' Based on the concentrations of petroleum hydrocarbons detected in on-site monitoring wells, AGE <br /> recommends replacement of the monitoring wells located near the former UST No 8 location In , <br /> addition,remedial action should be initiated to address the petroleum hydrocarbon-impacted ground <br /> ' water plume at the site <br /> Advanced GeoEnviron mental,Inc <br /> I <br /> ' F <br /> 1 <br />