ARCHIVED REPORTS_XR0005224 - Laserfiche WebLink

Home Browse Search

! YV/, A s s o C 1 A 7 E 5 I N C ! 5.0 CONCLUSIONS ! TPHg detected in the groundwater samples collected from MW6a indicates the hydrocarbon plume extends offsite in the shallow aquifer. MTBE detected in groundwater samples collected from MW6b, MW6c, MW7a, MW7b MW7c, and MWIOb indicate the MTBE plume extends ' offsite to the east in deeper groundwater. MTBE concentrations in MW7a and MW7b are below action levels. MTBE concentrations in MW6b and MW6c increased when compared with the December 13, 2004 groundwater monitoring event. BTEX components were not detected during the March 16-17, 2005 event in MW I, MW4, MWS, ' MW6a, MW6b, MW6c, MW7a, MW7b, MW7c, MW8, MW9a, MW9b, MW9c, MW10a, MW 10b and MW 10C. Although benzene, toluene, ethylbenzene and/or xylenes were not detected in MW1 during the March 16-17, 2005 monitoring event, these components were ' detected during first quarter in the earlier system monitoring events. Benzene, toluene, ethylbenzene and/or xylenes were detected in MW2, MW3 and EW1 during the March 16-17, 2005 event. ' Benzene appears to be declining or cleaned-up due the C-SpargeTM operation in MW1, MW2, MW4 and possibly EW-1. DO also increased significantly after system start-up in MW1 from 0.36 mg/L on 3 June to 5.17 mg/L during the March 16-17, 2005 event suggesting a further correlation. ' System effectiveness with respect to MTBE in the Jamar on site wells appears to be positive for MW 1. The responses (i.e., destruction of MTBE) to the system operation for MW2 and MW4 are not as clear. 6.0 RECOMMENDATIONS ' Based on the results of the First Quarter 2005 monitoring episode, ATC makes the following recommendations: ' ■ Conduct second quarter groundwater monitoring and sampling of MW through MWIOC and EWI and analyze the samples for TPHg, BTEX, MTBE, ETBE, DIPE, TBA, TAME, ' 1, 2-DCA and EDB. ■ Conduct monthly groundwater monitoring and sampling for field parameters including DO and ORP in the on-site remediation well network (MW1 —MW5, MWS and EW1) ' Continue operation and monitoring of the C-SpargeTM system for existing parameters and include electrical meter readings. ■ Install a system flow meter. Evaluate system flow on IW5 and install individual flow meters if necessary. ■ Increase the operating times of the deeper injection points and decrease the operating time of the shallower injection points for selected areas. ■ Review off site MTBE well response over time (in detail) for the intermediate and deeper intervals. ' 5:1268231QM reports12005 1 stQR.doc 12