ARCHIVED REPORTS_XR0009421 - Laserfiche WebLink

Home Browse Search

�C\VATC U%`r \ A S S O C I A T E S I N C The boring was subsequently completed as groundwater monitoring well MW7. The monitoring well was constructed of 2-inch inside diameter schedule 40 PVC well screen and casing. A 0.020-inch well screen slot and #3 sand pack was used. A cement grout mixture was used to seal the well in accordance with California Well Standards (December 1981). To protect the integrity of the well, a locking, watertight well plug was installed on the well and a watertight wellhead Es; labeled "monitoring well" was concreted over the well. Well construction details are presented on the boring log contained in Appendix A. 2.2 Soil Sam lin Each soil sample was field screened with a Flame Ionization Detector (FID) for the presence of volatile organic compounds. Background concentrations were measured at 7 ppm. The maximum FID reading from boring MW7 was 20 ppm. Sample tubes were sealed at each end using Teflon tape and plastic end caps, labeled, and placed on ice. Selected soil samples were kept on ice and delivered under chain-of-custody documentation to State-certified Argon i Laboratories Inc. (DHS Cert. No. 2359)for chemical analysis. 2_3 Well Development and Groundwater Sampling Measurement of depth to water in all wells (MWI through MW7) was completed on February 13, 2002 to evaluate the direction and magnitude of the groundwater gradient beneath the site. Depth to water measurements are presented in Table 4. The new well, MW7 was developed using surge and bail techniques until the produced water was relatively sediment free. Groundwater samples were collected from all seven monitoring wells. A sheen was observed in well MW4 but no measurable free product was present. Prior to the collection of groundwater samples, a minimum of three well volumes (casing and sand pack) was purged. Temperature, pH, and electric conductivity was measured and allowed to stabilize. =! Water samples were collected using disposable bailers; one dedicated to each well. Groundwater samples were submitted using chain-of-custody record to Sequoia Analytical Laboratory (DHS Cert. No. 1624). Groundwater samples, seven total, were analyzed for TPHd by DHS LUFT method. Purge water was stored in 55-gallon drums approved for hazardous liquid storage pending laboratory analysis. On April 3, 2002, the new wellhead elevation was surveyed by ATC and tied into the elevations of the existing wells. Measurement of depth to water in all wells (MW 1 through MW7) was also completed to confirm the gradient direction and magnitude. �f w;IWordpro162574162574.021Reporlslwell_inslall.doc 5