ARCHIVED REPORTS XR0012276 - Laserfiche WebLink

Home Browse Search

i" Report: Groundwater-quality Monitoring—July 14-15,2006, 7500 West Eleventh Street, Tracy,CA. Page 13 4- Well MW-19 remains free of any analytes of concern, it is clear that there has been no additional down-gradient migration of affected groundwater in the plume. i- 2.5.3 Anal es of Concern in Secondary Groundwater Plume Consistent with the presence of relatively amplified concentrations of analytes of concern �— in groundwater recovered from wells in July of each year, the concentration of TPHd in the sample recovered from Monitoring Well MW-12 on July 15, 2006 of 51 p.g/L compares to the non-detectable level of TPHg in the sample recovered from that well in i' March 2006, although benzene, the only other analyte of concern detected in the March 2006 sample,was not detected in the sample recovered from that well in July 2006. 2.6 Monitoring of Floating Product On July 8, 2006, Monitoring Wells MWFP-1 through MWFP-5 and groundwater-quality Monitoring Wells MW-7, MW-13 and MW-14 were checked for the presence of LNAPL floating on the groundwater by slowly lowering a hydrocarbon/water interface probe into each well. As is recorded in Table 3, no floating product was detected in any of those wells except for Well MW-7, in which a thickness of 0.05 ft. of floating product was measured. That thickness of LNAPL was an increase from the thickness of <0.01 ft. recorded on March 29, 2006. The small quantity of LNAPL present in Monitoring Well MW-7 was removed when that ` well was purged prior to recovery a groundwater sample on July 15, 2006. 2.7 Monitoring of Potable Water supplies The ninth round of potable water-quality monitoring that was conducted in July 2006 encompassed recovery of water samples from the following two addresses: 7500 West Eleventh Street 23901 South Chrisman Road 4 2.7.1 Recovejy and Analysis of Sam les from Potable Water SIMply Wells 4 Before the recovery of potable water samples, each well pump was turned on and water was flushed through the sampling port for a few minutes. Laboratory-supplied glassware, with, as appropriate, pre-dispensed preservatives, was then completely filled with water �.. from the sampling port. When full, the glassware was tightly closed, labeled for identification, and transported to STL's laboratory in Pleasanton, California. �.. Each water sample was analyzed for the following suite of analytes: ` sic