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SIMI-ANNUAL SAMPLING EVENT REPORT OF 6/11/2002 SAMPLING PROCEDURE Monitoring wells were vented and purged by normal methods per standards of the industry (see Groundwater Field Report by Del-Tech Geotechnical Services attached) Purge pump rates were +/-0 5 gallons per minute in all monitoring wells Groundwater samples were extracted from each monitoring well using the check valve in tube technique Samples were transported on ice for delivery under chain of custody to Sherwood Labs for analysis WATER TABLE ELEVATIONS AND GRADIENT Soundings on the monitoring wells showed the groundwater elevation has raised+/- 2' feet from the last soundings on 9114/01 The hydraulic gradient of the water table is directly east at S=0 0014 This is a change from the last sampling event that had a bearing of north WATER SAMPLE ANALYSIS FINDINGS In general, monitoring well samples taken on 06/11/02 were very similar to the previous sample events MW-3S continues to be the only monitoring well with B 1 hX compounds detcrmined by EPA Method 602 and 5030/8015(M) TPHg in this well was analyzed at 1090 ug/L The purgeable Halocarbon 1,2-Dichloroethane continues to be present in all of the wells with the exception of MW-4S and MW-413 For the first time on record, Tetrachlorethene was analyzed in monitoring wells MW-2S, MW-3D, and the new wells MW-5S and MW-5D For this event,new monitoring well MW-5D had the highest recorded values of the compound 1,2- Diehloroethane sense the starts of this investigation(see recap of data attached) • CONCLUSIONS BTEX compounds for this event in the MW#3S remain in the same range as the past events This monitoring well is receiving the highest impact of all the wells due to TANK#1 (the Stoddard's Solvent tank),which is usually up gradient and Southwest of MW#3S Low concentrations of 1,2- dichoroethane remain in monitoring wells MW#1,MW#2S,MW#2D,MW#3S,MW3D and MW- 5S and MW-513 REC:OMMENDA i IONS The author requests that all monitoring wells continue to be sampled in semiannual events to conserve financial resources WORK IN PROGRESS A receptor survey to indicate possible groundwater extraction within 2000' of the site is in the planning stages Please contact this office at 2Q9/368.9381 i uestions arise from this report ReSpmtfully submitted, Foo ngi enn No 19#2 c Ervin Rifen iSOF cc Mrs Helen Higgins, 5815 Morgan Place , Stockton CA 95219 2