ARCHIVED REPORTS XR0009966 - Laserfiche WebLink

Home Browse Search

DISCUSSION Results of this monitoring event indicate that concentrations of dissolved gasoline hydrocarbons in wells MW-1 through MW-7, and MW-10 are consistent with levels detected in previous sampling events, with the following exceptions Well MW-3 contained an ethylbenzene concentration of 4 45 micrograms per liter (µg11) MTBE was detected in well MW-6 at a concentration of 8 86 µg/1 using USEPA Method 8020 and confirmed at a concentration of 3 7 µg/1 using USEPA Method 8260 The groundwater gradient and direction of groundwater flow (east-southeast) were generally consistent with previous data Groundwater elevation decreased approximately 1 26 feet from the previous sampling event (December 1998) The oxygenates, tertiary butanol, MTBE, DIPE, ETBE, and TAME were analyzed in samples collected from groundwater monitoring wells MW-1 through MW-7, and MW-10 using USEPA Method 8260 Wells MW-2, MW-5, and MW-6 contained MTBE concentrations of 4 2 µg/I, 6 34 4g/l, and 3 7 µg/l, respectively Due to non-detect analytical results for oxygenates (other than MTBE) using USEPA 8260 for all wells, Pinnacle, on behalf of ARCO, requests no further analysis for oxygenates with the exception of MTBE using only USEPA Method 8020 - Pinnacle shut down the SVE system on November 24, 1997, due to low soil vapor concentrations and is currently pulsing the system on a periodic basis The SVE system remained shut down during the second quarter 1999 The air sparge system was shut down on November 24, 1997, along with the SVE system to evaluate feasible remediation alternatives Based on data and remediation techniques evaluation, the air sparge system was restarted on January 20, 1998, and operated at a low flow rate for bubbling and oxygen addition to the groundwater The addition of oxygen into the groundwater will help to promote biodegradation of petroleum hydrocarbons in impacted groundwater at the site As a result of air bubbling in air sparge wells AS-1, AS-2, and AS-3, since January 1998, dissolved oxygen levels in monitoring wells MS-1(s), MS-2(s), MS-3(s), and MW-2 have increased significantly as shown in Table 5 Pinnacle will continue to monitor the effects of the SVE system pulsing and air bubbling during the third quarter 1999 ATTACHMENTS • Table 1 Groundwater Monitoring Data • Table 2 Groundwater Analytical Results for Oxygenates • Table 3 Operational Uptime Information of the Soil Vapor Extraction System • Table 4 Flow Rates and Results of Air Sample Analyses • Table 5 Extraction and Emission Rates • Table 6 Air Sparge/Air Bubbling Flow Rates and Dissolved Oxygen Levels • Figure 1 Site Location Map • Figure 2 Groundwater Analytical Summary(Second Quarter 1999) • Figure 3 Groundwater Elevation Contours (Second Quarter 1999) • Appendix A Sampling and Analysis Procedures • Appendix B Chain-of-Custody Records and Laboratory Analysis Records • Appendix C Operation and Maintenance and Groundwater Monitoring Field Data Sheets • CP1C`Archive\Axo12130\Qtr1y12130Q299 DOC-9811%1 PGKsw&