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� 1 Third Quarter 1993 Status Report September 17, 1993 Golden Grain Company, Manteca Bean Facility, 229 Moffat Blvd , Manteca CA 3 -f for the sampling event on August 18, 1993, are included in Attachment 4 Results of system historical analyses are summarized in Table 3 During this quarter, the air stripper was dismantled V and cleaned on July 22 and August 5, 1993, for normal maintenance needed to keep the unit at peak operating efficiency There was no discharge of system water during these maintenance events (see page 4, Treatment System Summary) A total of 217,848 gallons of water were treated between June 28 and September 2, 1993 Dunng this reporting penod, the vapor treatment system was monitored each week following June 28, 1993 The Influent and effluent vapor concentrations were measured for TPH-G using a flame- ionization detector (FID) Values measured during site visits this quarter are shown in Table 4 The average destruction efficiency of 99 22 percent was calculated using weekly FID readings of the catalytic oxidizer effluent vapor stream for the operational period from June 28 through September 2, 1993 All effluent readings collected were below the 100 parts per million by volume (ppmv) TPH-G lima specified by the Unified Air Pollution Control District's permit to operate Using the flow rates and TPH-G concentrations measured each week, the amount of TPH-G removed from soils at the site can be estimated Based on the TPH-G concentrations and system flow rates obtained during field visas, approximately 562 pounds of TPH-G were removed from the soil by the vapor extraction system during this quarter The cumulative amount of hydrocarbons removed by the vapor extraction system since startup Is estimated at 2,549 pounds Calculations for mass removal for the third quarter are included in Attachment 3 VAPOR EXTRACTION MONITORING On August 18, 1993, vapor extraction monitoring was conducted to evaluate the subsurface effects of the vapor extraction system (VES) and quantify the static vapor concentrations of TPH-G in the sods located within the VES treatment area On August 18, 1993, air samples were collected for analysis from the VES influent, the effluent of the lead scrubber, and the effluent of the catalytic scavenger unit The samples were analyzed for BTEX, TPH-G, total lead, and organic lead Results of laboratory analyses are shown on Table 5 Laboratory results indicate that effluent concentrations of TPH-G and xylene are 15 and 1 part per billion (ppb), respectively, while other compounds or analytes that were analyzed for were nondetectable These effluent analysis results are below the 100 ppmv TPH-G limas set by the Unified Air Pollution Control District's permit to operate Before system sampling, the applied vacuum was measured at the two vapor extraction wells, and I the induced vacuum was measured at the monitoring wells within the VES treatment area (rabies 7 and 8) Readings were taken using a magnahelic gauge, measured as inches of water vacuum Readings were gathered to determine system efficiency and the radius of influence from the vapor extraction wells Results indicate the expected vacuum effect on the surrounding area, e g, larger 38798013 076 GROUNDWATER ❑ TECHNOLOGY, INC