ARCHIVED REPORTS_XR0005226 - Laserfiche WebLink

Home Browse Search

ti ' It is unclear what the system impacts are (for MTBE) in MW2, MW4 and EW-1 at this time. DO increased significantly after system start-up in MW2 from 1.39 mg/L on June 3, 2004 to 3.81 ' mg/L on September 13, 2004, MTBE concentrations decreased only slightly from June 3, 2004 (160 ug/L) to September 13, 2004 (140 ug/L) and it is unclear if the C-SpargeTM system is actually reducing concentrations currently. If the C-SpargeTM system were starting to reduce ' concentrations, the groundwater sampling results may indicate an immediate rise in concentration of MTBE due to mixing followed by a progressive drop in concentration. The agitation of the groundwater and capillary pores by the fine bubbles strips adsorbed fractions. The mixed ' concentrations are often a better measure of total mass for treatment than solely the aqueous fraction. ' DO may have increased very slightly in MW4 but the September 13, 2004 MTBE concentrations appear seasonally related or similar to values in September in previous years. DO may have increased very slightly in EW1 but concentrations are fairly consistent over time. The change in areal extent of MTBE from June 3, 2004 monitoring event to the September 13, 2004 monitoring event appears negligible (Figure 22). ' 4.5.3 TPHg During this monitoring period, TPHg concentrations in most wells appeared to remain fairly consistent (i.e., MW3) or showed fluctuating trends (MW2, MW5) when compared with concentrations prior to system start-up on June 17, 2004. The TPHg concentrations appeared to decrease significantly in MW I, MW4 and EWL DO increased significantly after system start-up in MW1 from 0.36 mg/L on June 3, 2004 to 4.72 ' mg/L on September 13, 2004. DO may have increased very slightly in MW4 and EWL The successive decline of TPHg in MWI from 54,000 ug/L on June 3, 2004 in each of the monitoring events following (i.e., July 16, 2004, August 13, 2004 and September 13, 2004) was significant. During the September 13, 2004 event, TPHg was reported at 820 ug/L for a removal efficiency of 98.5% after approximately 3'/2 months of operation. ' The successive decline of TPHg in MW4 may have accelerated from 4800 ug/L on June 3, 2004 to later monitoring events (i.e., July 16, 2004, August 13, 2004 and September 13, 2004). During the September 13, 2004 event, TPHg in MW4 was reported at 320 ug/L. If this reduction was ' attributed solely to system activities this would equate to a removal efficiency of 93.3% after approximately 3%z months of operation. (Note. It is unclear at this time with the limited data if this is the case.) The successive decline of TPHg in EW1 from 85,000 ug/L on June 3, 2004 in each of the monitoring events following was also significant. During the September 13, 2004 event, TPHg was reported at 1800 ug/L for a removal efficiency of 97.9% after approximately 3'/z months of operation. ' s:1268231QM reports12004 3QR.doc 10 ATC Associates Inc.