ARCHIVED REPORTS_XR0012668 - Laserfiche WebLink

Home Browse Search

R Hamm ON I-OW, a Addendum to Preliminary Report July 21, 1989 Former Texaco Service Station, Manteca, California AGS 38053-1 4. Applied GeoSystems concurs with this statement, as stated in our Work a for valuafo of o' and ound-Water ontamina iopr (August 8,1988),"Each sample will be inspected with a photoionizing hydrocarbon vapor detector. These devices are useful for the semiquantitative evaluation of the relative concentrations of volatile hydrocarbons but cannot be used to give absolute levels of contamination." Because these field devices are semiquantitative, appropriate soil samples are analyzed in a laboratory certified by the State of California. S. The location where ground water was first encountered has been added to the Logs of Borings (Plates P-4 through P-9) attached. 6. In the opinion of Applied GeoSystems, listing a concentration in parts per million (ppm) rather than parts per billion (ppb) on an Analysis Report has no effect on whether the concentration may be "accidentally" reported as Not Detected (ND). Benzene was not detected in sample W-27-MW-1 at a detection liiait of 0.0005 ppm (or 0.5 ppb)just as stated on the Analysis Report. 7. We have included the stamp of the Registered Geologist in overall charge of the project on this addendum. 8. It is the opinion of Applied GeoSystems that construction of one additional monitoring well within 10 feet of the former tank cavity, as requested by the DEH, should be delayed until the excavation proposed in Applied GeoSystems Work Plan No. 38053-2, dated May 4, 1989, has been conducted and the excavated cavity backfilled. This will prevent possible damage to the well or having to abandon the well during excavation because of its close proximity. 9. Quarterly sampling of the monitoring wells will be initiated after the proposed excavation is accomplished. 2 .4R)711ed Geo�ysterrr�