ARCHIVED REPORTS XR0011055 - Laserfiche WebLink

Home Browse Search

1 C#44teal red"=141 Page 4 Groundwater Monitoring Report Project No 724 2 May 16,2005 ' 1.2 Groundwater Sampling Procedure On April 18, 2005, 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 In wells where free-floating product ' is suspected, a clear disposable bailer is used to gauge the interface No free-floating product was observed during this monitoring event Well MW-1, MW-3, MW-4, MW-5, MW-6 and MW-104 were not sampled in this monitoring event as per SJCEHD letter correspondence November 24, 2004 However, these wells will be sampled during 1"and 3rd quarter Stagnant water in the well casing was purged using a dedicated Wattera pump as recorded in ' the field logs (Appendix C) The rate of well purging was monitored The wells were purged of at least three casing volumes until the groundwater parameters (temperature, conductivity, ' and pH) had stabilized (Appendix C) Groundwater parameter stabilization was characterized by three successive readings within 10% variance ' Before a sample was collected, the water level was allowed to recharge to at least 80% of the initial level All purge water removed from the monitoring well was placed in a properly labeled 55-gallon DOT (Department of Transportation 17-H) approved container and is temporarily stored on-site A dedicated Wattera pump was used to collect each sample Sample from MW-110 was a ' grab sample due to poor recharge Water samples were transferred in a manner that minimizes sample aeration during transfer ' of the sample into 40-m1 VOA vials preserved with hydrochloric acid All samples were checked for headspace bubbles, labeled, inserted into foam holders and placed into an ice chest cooled to 4°C for transport to the laboratory The sampling technician, while collecting all samples, wore disposable gloves ' 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 1.3 Laboratory Analyses tThe groundwater samples collected on April 18, 2004, were delivered to Sequoia Analytical Labs of Sacramento, California (certification#1624) for analyses of ' • Benzene, Toluene, Ethyl Benzene, and Xylene (BTEX) by EPA method 8021(B) • Total Petroleum Hydrocarbons as Gasoline (TPH-G) by EPA method 8015(M) • MTBE by EPA 8021B 1