ARCHIVED REPORTS XR0000978 - Laserfiche WebLink

Home Browse Search

Former Valley Water Treatment Page 3 Quarterly Groundwater Monitoring Report Project No. 480.2 ' r May 16, 2006 ' 2.0 GROUNDWATER MONITORING The following sections describe the procedures associated with the completion ' of groundwater monitoring and ancillary.activities at the site. 2.1 Groundwater Sample Collection ' On March 21, 2006, Del-Tech Geotechnical Services of Oakdale, CA mobilized to the site to complete groundwater monitoring field work. The groundwater monitoring procedure was as follows: Upon arrival, each well was opened and the water level allowed to equilibrate. ' As each well was opened, and prior to taking the depth to groundwater measurement, a PID organic vapor meter was used to screen for VOC's in the head space of the wells which were to be sampled. The depth to groundwater was then measured by lowering an ' electronically actuated air I water interface detector suspended from a polyethylene measuring tape calibrated to the nearest 0.01 foot (see groundwater monitoring data sheets in Appendix B). A careful notation was ' made of the depth to groundwater as measured by the device. No measurable free product was observed in the wells., Each well was pumped with a Waterra pump with dedicated vinyl tubing. Well water was containerized in 55-gallon, DOT approved polyethylene drums, ' properly labeled, and temporarily stored on-site. The rate of well purging was monitored, and each well was purged of at least three casing volumes or until the groundwater parameters (temperature, conductivity, and pH) had stabilized indicating that water representative of actual aquifer conditions was entering the well. Groundwater parameter stabilization was characterized by three successive readings within 10 percent. After the wells had been allowed ' to recharge to at least 80 percent of their original volume, samples were collected from them using methods described below. Samples were collected directly from the dedicated tubing. The sample liquid was very slowly produced into new 40 ml VOA sample vials that were provided by the laboratory. Extreme care was exercised while collecting samples to prevent agitation of the water. All, samples were checked for head space bubbles, labeled, inserted into foam holders and placed in an ice chest cooled to I4°C for transport to the laboratory Disposable gloves were worn by the sampling technician while collecting all samples. The gloves were changed between the collection of each sample to reduce the potential for cross-contamination. • 2937 Veneman Ave.,#13240 Geo-Phase Environmental Inc. Phone (209) 569-0293 Modesto, CA 95356 Fax (209) 569-0293 I