FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

13 September 2012 AGE-NC Project No.99-0682 Page 16 of 17 MW-8 throughout the pilot injections. Following ISCO injections, temperature remained elevated in both injection wells, while DO and ORP stabilized to near background levels.Observation wells MW-6 and MW-7 were marginally-effected by pilot injections based on field parameters collected during and after injections. Field parameter measurements of ORP and DO are summarized in Table 1. • Based on progress and post-ISCO sampling,dissolved metals generally decreased or remained stable in well MW-1A; marginally increased in well MW-6; increased in well MW-8; and generally remained stable or fluctuated in wells MW-7 and MW-10 (Table 4).Specifically, Fe and Al concentrations increased in well MW-8 significantly compared to baseline concentrations, but have been steadily declining after termination of the pilot test. Additionally, Cr was detected in the samples collected from MW-8 during the 28 June and 12 July 2012 post-ISCO sampling events; Cr decreased to non detect levels during the final post-ISCO sampling event on 12 July 2012. Concentration of Cr detected were below the State Primary MCL of 0.05 mg/I. • Based on progress and post-ISCO sampling, anions bromide and bromate fluctuated throughout the pilot test in wells MW-1A, MW-6, MW-7 and MW-8. By the end of the pilot test, bromate and bromide were detected at concentrations consistent with baseline levels in injection wells MW-1A and MW-8, and had increased slightly in samples from observations wells MW-6 and MW-7, with the exception of bromate in well MW-6 which decreased to below baseline levels. (Table 5). • Chloride, nitrate as nitrogen, nitrate as nitrate and sulfate generally increased in all wells, while ammonia generally decreased (Table 4). • CrVI was not detected in any samples collected during the pilot test. Based on these results, and general fluctuations of bromide and bromate, it appears that water quality was not adversely effected by the ISCO injections performed at the site. • TPH-g concentrations in injection well MW-1A decreased 72% in comparison to baseline sampling concentrations and benzene concentrations decreased 90% in comparison to baseline sampling results collected in April 2012; additionally, the remaining BTEX compounds decreased significantly compared to baseline and historical sampling results. Graphs depicting concentration trends versus time during the pilot test are presented in Appendix E. • TPH-g concentrations slightly decreased in well MW-7 (24%), while benzene concentrations decreased 70%; the remaining BTEX compounds decreased moderately compared to baseline and historical sampling results (Appendix E). • Following the first two weeks of injections, TPH-g and benzene concentrations significantly decreased in well MW-8 (Appendix E; Table 3). Following the fourth Advanced GeoEnvironmental,Inc.