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MRS • Mr Michael Infuma Page 2 San Joaquin County Environmental Health Department September 2, 2003 SCOPE OF WORK URS conducted vertical groundwater flow on SVE wells VW-2 and VW-10 and well condition assess- ments on groundwater monitoring wells MW-2 and MW-5 Welenco, Inc , of Bakersfield, California was subcontracted to perform the depth-discrete vertical flow analysis for wells wells VW-2 and VW-10 using a FloVisionTM flowmeter probe The FloVisionT'* apparatus indicated the direction and flux of groundwater movement within the wells Analyses were performed at approximately 2-foot depth intervals along the submerged portion of the screen interval listed in Table 1 Data from the FloVistonT"^ apparatus was used by Welenco to create profiles for wells VW-2 and VW-10 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 VW-2 and VW-10 are acting as vertical conduits for shallow contamination to impact deeper water-bearing zones Additionally, a separate down-hole camera designed to photograph the interior of wells MW-2 and MW-5 was used to assess the condition of wells(weeping perched layers, breaks in the casing,debris on the well bottom, biological growth, etc ) . RESULTS Inspection of well VW-2 found the well intact The FloVisionTm apparatus encountered groundwater at 43 feet below ground surface (bgs) and was run to a depth of approximately 58 feet bgs Analysis of groundwater flux findicates downward flow is occurring at the very bottom of the well from 55 feet to 58 feet bgs Recorded flow was too slow to be measured accurately (below 1 foot per minute [fpm]) however an averaged rate of 0 34 fpm with an averaged flow volume of 0 22 gallons per minute (gpm) were estimated No vertical flow was recorded in the upper portion of the well (43 feet to 55 feet bgs) Geology at this location consists of silt from 23 feet to 53 feet bgs with a silty sand layer from 53 feet to 58 feet bgs From 58 feet to 62 feet is another silt layer with silty sands from 62 feet to the maximum well depth of approximately 64 feet The vertical flows recorded are Iocated in the silty sand layer located between two silt layers (see boring log in Attachment B) Because of sediment to the well, vertical flow readings could not be recorded below 58 feet Inspection of well VW-10 found the well intact The FloVisionTm apparatus encountered groundwater at 44 feet bgs and was run to a depth of approximately 54 feet bgs Analysis of groundwater flux indicates there is no flow Video logging of wells MW-2 and MW-5 showed the wells to be in good condition with no broken or damaged sreens The FloVisionTm apparatus encountered groundwater at 44 feet bgs for well MW-2 and was run to a depth of approximately 73 feet bgs For well MW-5 the apparatus encountered ground- water at 43 feet and was run to a depth of approximately 68 feet bgs i K 1WprocessU5 BP ARC0102I30Wertical Flow Study12130 Vgradient Report V2 doe