ARCHIVED REPORTS_XR0003886 - Laserfiche WebLink

Home Browse Search

Each well was purged before collecting water samples Purging was completed only after water temperature, pH, and conductivity had stabilized Purged water was contained in a labeled, secured 55 gallon drum on site The wells were allowed to recover after purging A water sample was then collected with a fresh bailer Each sample was divided among three 40-m1 VOA vials The vials are supplied pre-cleaned to exact EPA protocols and contain the appropriate preservative The sample vials were labeled as to station, well, time, and sampler, and documented on the chain-of-custody sheet, they were then placed into an ice chest and cooled to 40C with ice The samples were delivered to a California State Certified Laboratory and signed over to the lab using standard chain-of- custody procedures Field notes describing the collection of water samples are included in Appendix A Chemical Analysis Results The water samples were analyzed at Anlab Analytical Laboratory (DHS #1468) for Total Fuel Hydrocarbons (gasoline) with BTEX distinction, utilizing EPA Methods 5030 and 602 , respectively The analytical results from the water samples (MW1, MW5 , MW6 and MW7) were all, Below Reportable Limits (BRL) MW2 , MW4 and MW8 indicated a level of TFH of 046 mg/L, 4 9 mg/L and 6 mg/L respectively Benzene concentrations are 340 and 55 kcg/L for MW4 and MW8 respectively MW2 does not contain BTEX compounds above action levels The current localized impact of TFH-gasoline and benzene on ground water is depicted in Figures 5C and 6C The analytical results and pertinent reference data are listed in Table 1 Anlab' s laboratory report is included as Appendix B DISCUSSION OF RESULTS The ground water data obtained during the current monitoring round show significant changes since the last quarterly monitoring report Ground water flow direction is to the south- southeast with an average gradient of 0 002 feet per linear foot Ground water at the site is currently in a discharge cycle Previous discharge and recharge cycles at the site have produced sporadic traces of TFH or BTEX constituents in some of the monitoring wells The ' spotty' occurrence of contamination in MW4 does not appear to be solely related to depths of the aquifer but are probably representing a localized ground water flow from stratigraphy not recognized from well to well at the site Currently, there are slight levels of dissolved petroleum hydrocarbon constituents in MW2 4