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S E C ® R QUARTERLY RESULTS SUMMARY Current Phase of Project Monitoring/Remediation ' Frequency of Groundwater Sampling MWA through MW-11, EW-1 through EW-7, DMW-1 through DMW-3, and SVE-1 Sampled Quarterly ' Frequency of Groundwater Monitoring Quarter) Is Free Product (FP) Present Onsite No Current Remediation Techniques SVE/GWE (onsite), Ozone S ar a offsite ' TPHg removed this quarter (Ibs) 53 (SVE), 0 5 (GWE) MtBE removed this quarter(Ibs) 1 (SVE), 0 3 (GWE) TPHg removed -cumulative (Ibs) 24,223 8 (SVE + GWE) ' MtBE removed- cumulative (lbs) 2,012 (SVE + GWE) Groundwater extracted this quarter 145,000 (GWE) ' Cumulative groundwater extracted 1,307,600 (GWE), 121,740 (Batch Extraction) Approximate Depth to Groundwater 29 80—32 39 ft Groundwater Flow and Gradient Shallow— Radially Outward (ARCO) ' Northwest @ 0 005 ft/ft Intermediate—Northeast @ 0 007 ftlft Deep— Northwest @ 0 07 ft/ft(ConocoPhillips wells) DISCUSSION- Total petroleum hydrocarbons as gasoline (TPHg) were reported in eight of the twenty wells sampled this quarter at concentrations ranging from 57 ppb (MW-2) to 12,000 ppb (MW-4) Benzene was reported in two of the twenty wells at a maximum concentration of 940 ppb (MW-4) Methyl tertiary butyl ether (MtBE), yi analyzed using EPA Method 82606, was reported in twelveof the twenty wells at concentrations ranging ' from 0 87 ppb (DMW-1) to 8,800 ppb (EW-2 ) 1,2-Dichloroethane (1,2-DCA) was reported in nine of the wells analyzed at concentrations ranging from 0 80 ppb (MW-2) to 38 ppb (MW-1) Tertiary butyl alcohol (TBA) was reported in one of the well at a concentration of 77 ppb (EW-1) Decreases in concentrations of ' petroleum hydrocarbons and MtBE continue to be observed in several of the site wells as a result of remedial system operation Groundwater flow within the shallow water-bearing zone was radially outward beneath the ARCO site and to ' the northeast at a hydraulic gradient of 0 005 ft/ft beneath the ConocoPhillips site Groundwater flow within the intermediate water-bearing zone was to the northeast at an approximate gradient of 0 007 ft/ft The groundwater flow direction and hydraulic gradient reported for the shallow and intermediate water-bearing ' zones during the second quarter 2005 were also consistent with historical data Groundwater flow within the deep water-bearing zone was to the northwest at an approximate gradient of 0 07 ft/ft All deep zone wells were installed by ConocoPhillips and are located on the adjacent ConocoPhillips property ' Groundwater extraction (GWE) and soil vapor extraction (SVE) continued at the site The weekly batch extraction events were discontinued after February 23, 2005 due to the installation of offsite ozone sparge wells and pending offsite remedial system installation Remediation at the site will be expanded to include ' the installation of an offsite ozone sparging (OS) system on the adjacent Taco Bell property SECOR has installed the offsite OS wells and OS system was started on .July 12, 2005 A remedial performance summary of site remediation activities is included in Attachment A SECOR's , ' procedures for groundwater sampling and equipment decontamination are included in Attachment B The ri certified laboratory analytical reports, chain-of-custody documentation, and field data sheets are included as Attachment C Groundwater monitoring and sampling was coordinated with activities performed at former 76 Service Station No 4409, located northeast of the site Attachment D contains the data prepared for this site by x ' I I13P-ARC01493ZQ1V1W200512Q1V1R05 doc t�,a