ARCHIVED REPORTS XR0001355 - Laserfiche WebLink

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CAMBRIA SYSTEM EVALUATION Continuous soil vapor extraction began on January 5, 1996 as permitted by San Joaquin Valley Unified Air Pollution Control District (Facility ID# N-3139, expiration date of 0810112002) Operation was maintained and monitored bimonthly by SECOR International Incorporated (SECOR) Bimonthly site visits included equipment inspection, influent and effluent soil vapor concentration measurements, and control system adjustments Review of SECOR's quarterly monitoring reports revealed variable operational downtime for Agshkk the thermox The downtime was incurred due to occasional power outages and frequent mechanical failures The periodic operating efficiency varied from 24% to 86%, and WIMPM low averaged 55% over its span of operation The historical data are presented in Table 1 Petroleum hydrocarbon concentrations in the influent air stream of the SVE system had been decreasing since operation of the thermox began in January 1996 The hydrocarbon removal rate and cumulative mass removal had been leveling off since August 1996, indicating an asymptotic trend Figure 3 presents the mass removal trend In September 1993, SEACOR • estimated 5,600 pounds (896 gallons) of petroleum hydrocarbons within the impact area SECOR reported in the first quarter 1998 monitoring report that the SVE system had removed 6,256 pounds of petroleum hydrocarbons upon shutdown Additionally, SECOR monitored individual well flow rates and hydrocarbon concentrations during the first quarter 1998 Over the duration of the first quarter 1998, the well concentrations showed an asymptotic trend to insignificant levels (<80 ppm) Table 2, from the First Quarter 1998 Monitoring Report prepared by SECOR, presents the field measurements for the individual wells CONCLUSION The SVE system appears to have reached the limits of its effectiveness onsite Influent and individual well concentrations decreased, mass removal rates leveled off, and the total mass removed exceed the estimated mass within the impact area Pulse operation of the SVE system may produce a slight rebound effect and optimize further mass removal However, additional mass removal by the SVE system would be minimal and not cost-effective Cambria recommends that the SVE system remain shutdown Restarting, and possibly enhancing, the SVE system may be re-evaluated for possible onsite or offsite use after additional site investigation is completed 3