Laserfiche WebLink
4.0 RESULTS <br /> 4.1 Depth to Groundwater and Groundwater Gradient <br /> X <br /> ' The depth to groundwater on June 5 was approximately the same as it was in March 2001 At the <br /> present depth of 30-31 feet, the water level is slightly above the contact between the aquifer sand <br /> and the underlying clay bed, but is at the base of the screened interval in VT-1 and SW-1 Neithei <br /> well was measured or sampled <br /> Figure 3 illustrates the hydraulic gradient and general direction of groundwater flow In general, <br /> the water table slopes to the east, as it has in the past However, the depth to groundwater in VM- <br /> 4 was anomalously shallow, apparently creating a mound around this well This may be due to <br /> the low hydraulic conductivity of the deposits surrounding this well, impeding the water in the <br /> well from percolating into the soil and preventing the static water level from falling to the <br /> piezometric level <br /> 4.2 Analytical Results <br /> In the first quarter of 2001, the wells were not purged before sampling, and the concentration of <br /> all analytes was low or even below detection limits The samples that were collected after <br /> purging in the second quarter had sharply higher concentrations of Total Petroleum Hydrocarbon <br /> and BTEX (Table 2) BTEX concentrations of 87, 170, 42, and 160 parts per billion (ppb) are all <br /> historical highs for VM-1 The benzene concentration of 21 ppb is also the highest that has been <br /> recorded from VM-3 Whether these increases are due to purging is uncertain <br /> 5.0 CONCLUSIONS AND RECOMMENDATIONS <br /> The sidewalk along Grant Street on the west side of the site has now been replaced, and it should <br /> be possible in the near future to obtain an encroachment permit from the City of Stockton for <br /> drilling in the City streets Upgradjent Environmental will forward the permit to PHS/EHD when <br /> ,f has been approved by the Public Works Department, along with the required drilling permit <br /> application We anticipate installing the additional wells during the third quarter of 2001, and <br /> groundwater monitoring will take place after the new wells are in place <br /> 3 <br />