ARCHIVED REPORTS XR0003991 - Laserfiche WebLink

Home Browse Search

' 05 May 1997 • AGE-NC Project No 95-0112 ' Page 8 of 14 MW-4, MW-5 and MW-7 were purged using pre-cleaned PVC bailers A minimum of three well ' volumes of water was removed from each well Ground water stabilization parameters(temperature, pH and electrical conductivity)were measured at regular intervals in each well using an ICM water analyzer Purged water was stored on-site in 55-gallon drums In accordance with monitoirng ' requirements for the site, MW-2, MW-6 and MW-8 were not sampled Stabilization data and field logs aie included in Appendix G 42 COLLECTION OF GROUND WATER SAMPLES Piior to sampling, the depth to water was remeasured in each purged well to aszure a ininrmuin of 80% recharge Water samples were then collected from each purged well using new disposable ' bailers The samples were transferred into 40-m1 EPA-approved VOA vials containing 0 5 ml of 18% hydrochloric acid as a preservative and were transported in a chilled container, under chain- of-custody, to Alpha Analytical Laboratories (AAL) in Ukiah All samples were analyzed for TPH-g ' and 13TE&X with MTBE in accordance with EPA methods 5030, 602 and 802.0, respectively ' 4 3 GROUND WATER ELEVATION AND FLOW DIRECTION ' Between January and April 1997 ground water elevation increased an average of 2 17 feet Ground water continues to remain below the tops of the screened intervals in all monitoring wells at the site The relative ground water elevation data is gi,,en in fable 5 As in pievrous monitoring events, ' ground water mounding was observed during the April monitoring event The giound water flow direction remained southerly During data review for the site, an error was discovered in the survey data for MW-3 Table 5 reflects the revised casing elevation for MW-3 Ground water elevation ' contour maps for October 1996 and January 1997 were redrafted to reflect the revised data(Figures 5 and 6) Relative ground water elevations for April 1997 are depicted in Figure 7 ' 44 LABORATORY ANALYSIS OF GROUND WAJ ER SAMPLES ' TPH-g and xylenes were detected in the ground water sample collected from MW-1 at concentrations of 51 parts per billion (ppb, reported as micrograms per litei) and 054 ppb, respectively Other petroleum hydrocarbons were not detected in samples collected from the site ' during the April 1997 monitoring event MTBE was not.detected at the site Tlie-andlytical results - of current and previous water samples are summarized in Table 6 The laboratory report (AAL, ' Batch No 97-0411-011) and chain-of=custody form are included in Appendix H 3 '