ARCHIVED REPORTS_XR0003659 - Laserfiche WebLink

Home Browse Search

. 2 GROUNDWATER FLOW DIRECTION AND GRADIENT On June 14, 2001 ASE measured the depth to water in each site groundwater monitoring well using an electric water level sounder The surface of the groundwater was also checked for the presence of free- floating hydiocatbons or sheen using an oil/water interface probe and a product thickness bailer Free-floating hydrocarbons were observed in monitoring wells MW-5, MW-6, and piezometer P-4 Groundwater elevation data is presented as Table One Groundwatei elevation (potentiometirc surface) contours aie plotted on Figures 2, 3 and 4 Gioundwater in the shallow zone (less than 20-feet bgs) has histotically shown a northern flow ASE installed a pump and ti eat" inter tm i emediation system in September 2000 to influence t h e offsite downgiadient flow pattern in the shallow zone The remediation system is causing a "coning effect" in the northern portion of the site Thi,, "coning effect i,, not readily visible in the shallow gi oundwatei contour map this quarter because the remediation system had been turned off for iegulai maintenance a few hours prior to measuring groundwater levels in the site monitoring wells When the remediation • system is in operation groundwater flows toward the recovery «ells Groundwater in the middle zone (55-70-feet bgs) appears to flow to t h e south with a gradient of approximately 0 001-feet/foot, which is consistent with pre,, sous findings The groundwater flow in the deep zone (greater than 100-feet) appears to flow to the southeast this quarter at a gradient of approximately 0 001 -feet/foot Potentiometric surface differences in wells adjacent to each other but screened in different zones (such as monitoring wells MW-6, MW-7 and MW-8) show a decreasing hydraulic head \pith depth, suggesting the potential for downward groundwater flow 3 . 0 GROUNDWATER SAMPLE COLLECTION On June 14 and 15 2001 , ASE collected groundwater samples from t h e site monitoring wells for analysis Prior to sampling, the site monitoring wells were purged of foul well casing volumes of groundwater using a Grundfos pump and/or dedicated polyethylene bailers The pH, temperature, and conductivity of the purge water were monitored dui rng evacuation, and samples were not collected until these parameter s stabilized Samples were collected from the wells using dedicated bailer,, • The groundwater samples were decanted from the bailers into 40-m1 volatile organic analysis (VOA) vials, preserved with hydrochloric acid Frank's One Stop Quarterly Report — June 2001 Sampling -2-