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URS • Mr Harlin Knoll Page 2 San Joaquin County Environmental Health Department September 2, 2003 Analyses were performed at approximately 2-foot depth intervals along the submerged portion of the screen interval listed in wells ATR-2 and TEX-I (Table 1) Data from the FloVisionTm apparatus was used by Welenco to create profiles for wells ATR-2 and TEX- 1 showing the direction (up or down) and flux of groundwater along the well screen as shown in Attachment A This information was used by URS to to determine if wells ATR-2 and TEX-1 are acting as vertical conduits for shallow contamination to impact deeper waterbearing zones Additionally, a separate downhole camera designed to photograph the interior of wells ATR-7 and ATR-8 was used to assess the condition of wells (weeping perched layers, breaks in the casing, debris on the well bottom, biological growth, etc ) RESULTS Visual inspection of the extraction well TEX-1 showed the well casing was collared down from 6 inches to approximately 2 inches Due to this contriction, only the 2-inch F1oVistonTm apparatus could be used with an adaptor for a 4-inch well The welt was found to be intact, with groundwater encountered at I1 feet below ground surface (bgs) and the bottom of the well at 38 feet bgs Analysts of groundwater flux indicates there is no vertical flow Inspection of well ATR-2 found the well intact The F1oVisionTm apparatus encountered groundwater at 12 feet bgs and was run to a depth of approximately 29 feet bgs Analysis of groundwater flux indicates there is no vertical flow I Video logging of wells ATR-7 and ATR-8 showed the wells to be in good condition with no broken or damaged screens The FloVisionT"apparatus encountered groundwater at 9 feet bgs for well ATR-7 and was run to a depth of approximately 24 feet bgs For well ATR-8 the apparatus encountered ground- water at 12 feet and was run to a depth of approximately 27 feet bgs Roots were seen intruding through the screen in well ATR-7 at a depth of approximately I 1 to 12 feet bgs Algae was observed in all of the wells See Attachment A for Welenco reports CONCLUSION Assessments of wells ATR-2 and TEX-1 showed no signs of vertical flow within the well This suggests that the ARCO wells, at the station referenced above, are not acting as vertical conduits for contaminant migration Video inspection of wells ATR-7 and ATR-8 show some algae on the well screens and well ATR-7 shows roots entering the screen • K 1WprocessU5 BP ARM02093Vertical Flow Study12093 Vgradient Report V2 doe