ARCHIVED REPORTS_XR0011011 - Laserfiche WebLink

Home Browse Search

KLEINFELDER I 6 CONCLUSIONS AND RECOMMENDATIONS On June 1 and 2, 2004, seven monitoring wells were purged and sampled. Water samples obtained from each location were submitted for chemical analysis. Based on the data obtained during our assessment, the following conclusions and recommendations have been formulated: 1. Groundwater flow direction at the site is calculated to be towards the southeast with a gradient of approximately 0.006 ft/ft. 2. The seven downgradient well samples showed a decrease of TPH-g concentration in MW-11s to a non-detectable result versus last quarter (61 ug/1). There were no other detections-of TPH-g in the other samples. There were no detected concentrations of any of the BTEX compounds in any of the downgradient wells this quarter. Additionally, there were no EDB concentrations detected at or above the laboratory reporting limit. TBA concentrations in each of the downgradient samples analyzed remained non-detectable concentrations for the second consecutive quarter. The concentrations of 1,2-DCA detected in the downgradient wells increased in 3 of the 7 samples (MW-11s, MW-12 and MW-15} from 130 ug/l, non-detect and 5.8 ug/1 to 160 ug/I, 1.2 ug/1 and 7.8 ug/l, respectively. The analyte 1,2-DCA decreased in one location (MW-14s) and remained non-detect in the remaining three samples. I. The samples collected from MW-14s , MW-14d, and MW-15 were analyzed for the fuel oxygenates MTBE, DIPE, ETBE, and TAME this quarter and showed non- detectable results. As evidenced by the known presence of TBA in wells MW-1, NP1-70, 80, and 90; concentrations may still be moving slowly across the site yet undetected in the past by the relatively low concentrations and high reporting limits previously employed. Coupled with the start-up/operation of the ozone/sparge system and lower laboratory reporting limits, TBA appears to have become mobilized and subsequently detectable. The concentrations noted in MW-11s, 11d, 12, 13, 14s, 14d, and 15 noted during the fourth quarter 2003 and subsequent drop to non- detectable levels during the first and second quarters of 2004, may be directly related to the remediation activities as deeper contamination is lifted into the shallower screened zones of the monitoring wells. Tftb`l�R'dfrd fiffi &9briation of concentrations may continue until the deep contamination at the source area is significantly mitigated. 3. Kleinfelder recommends that monitoring of the site should be continued in accordance with the "Groundwater Monitoring Frequency Decision Tree" at this time. 1 12280.MON/ST04R1092 Page 10 of 12 Copyright 21114 Kleinfelder,Inc. September 2,2004