ARCHIVED REPORTS_XR0008402 - Laserfiche WebLink

Home Browse Search

1 Kennedy/Jenks/Chilton As identified in the 13 October 1988 work plan, excavation of pesticide ' containing soil followed by disposal at a Class I landfill was selected for implementation A discussion of soil removal and disposal activities is presented in Section 3 ' ADDITIONAL SOIL AND GROUNDWATER INVESTIGATION For the purpose of collecting additional soil and groundwater data in ' the downgradient direction of the former tank location, one groundwater monitoring well (MW-5) was installed at the Cal -Farm site on 31 May 1990. The location of well MW-5 is shown on Figure 5. Petroleum ' hydrocarbons and benzene, toluene, xylenes, and ethylbenzene (BTX&E) were detected in groundwater collected from a well located upgradient of the tank during the preliminary site investigation. Those results are summarized in the Kennedy/Jenks/Chilton report entitled Preliminary Site ' Investigation Report, Cal-Farm Stockton Facility dated 14 July 1989 Monitoring Well Installation The soil boring for MW-5 was drilled to a depth of 25 feet using a truck mounted drilling rig utilizing ten-inch (nominal outside diameter) hollow-stem augers. Undisturbed soil samples were collected at five- foot intervals using a California modified split spoon sampler. Brass liners were inserted inside the sampler to retain the soil samples. The sampler was driven 18 inches into the soil at the appropriate interval using a 140 pound drive hammer free falling approximately three feet. The sampler was extracted and one liner from each interval was retained for laboratory analysis. Soil from the other two liners was used to ' describe site lithology. Groundwater was encountered in MW-5 at approximately 15-feet below ground surface. Lithologic descriptions of the site soil are included on the boring log presented in Appendix C. ' The soil samples retained for laboratory analysis were covered on both ends with Teflon sheets and tight fitting plastic caps. The samples were labeled according to location, date, depth, time, and sampler ' initials and placed in a chilled ice chest for shipment to the Kennedy/Jenks/Chilton laboratory Division. Chain-of-Custody forms were completed and accompanied the samples to the laboratory After drilling and sampling, the boring was completed as a monitoring well using two-inch Schedule 40 PVC well screen (0 020-inch slot size) and casing The screened interval extended from ten feet below ground ' surface to the bottom of the boring Ten feet of blank casing was placed above the screen for a total well depth of 25 feet. An �__ artificial filter pack consisting of Monterey #1C sand was placed around ' the casing extending from the bottom of the boring to approximately 1- 1/2 feet above the screened interval . A one-foot thick bentonite pellet seal consisting of hydrated 1/4-inch bentonite pellets was installed on top of the artificial filter pack. A cement/bentonite grout was placed above the seal and extended to the ground surface. The well was completed at the surface using a water- , WPI13 2 4 882526 01