ARCHIVED REPORTS_XR0011315 - Laserfiche WebLink

Home Browse Search

i Geological TecwcsInc. Page 2 Groundwater Monitoring Report Project No. 989.2 November 20,2001 located under Interstate 5. Three grated manhole covers are located along a trench-like basin formed by sloping asphalt above the storm drain. ' Frfteen groundwater monitoring events have been performed on MW-1, MW-2 and MW-3 since August of 1995. Four groundwater monitoring events have been performed on MW- 4, MW-5 and MW-6 at the site: August of 2000 and January, June and September of 2001. Monitoring well locations are located on Site Map, Figure 2. 2.0 GROUNDWATER MONITORING ' 2.1 Groundwater Sampling ' On September 27, 2001, Del-Tech Geotechnical Support personnel arrived on-site, opened the wells, and measured the depth to water with an electrically actuated sounding tape. The water level reading was recorded to an accuracy of 0.01 foot. If free-floating product were suspected, a clear disposable bailer would have been used to gauge the interface. No floating product was observed during this sampling event. Stagnant water in the well casing was purged using a centrifugal pump with dedicated tubing. The rate of well purging was monitored. The wells were purged of at least three casing volumes and until the groundwater parameters (temperature, conductivity, and pH) ' had stabilized (Appendix B) indicating that water, representative of actual aquifer conditions, were entering the well. Groundwater parameter stabilization was characterized by three successive readings within 10%. Before a sample was collected, the wells water level was allowed to recharge to at least 80% of its initial level. All water removed from the monitoring well and not used as a ' sample, was placed in a 55-gallon DOT approved container that is properly labeled and temporarily stored on-site. rThe technician using dedicated waterra pump and tubing collected the samples. The water was slowly decanted into 40-m1 VOA vials preserved with hydrochloric acid. Extreme care ' was exercised while collecting samples to prevent agitation. All samples were checked for headspace bubbles, labeled, inserted into foam holders and placed in an ice chest cooled to 4°C for transport to the laboratory. The sampling technician wore disposable gloves while collecting all samples. ' A chain of custody document, listing all samples collected and their intended analyses, accompanied the samples from field to the laboratory, thereby providing a means to track their movement and ensure their integrity. i i