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* FORMER AMERICAN FOREST PRODUCTS FACILITY Section No.2.0 Additional 1,2-DCA Investigation and Site Conceptual Model February 2005 And Second Quarter 2004 Quarterly Monitoring Report Page 2-1 2.0 FIELD ACTIVITIES r Quarterly groundwater monitoring rounds were conducted in June, September, and December 2003. Those rounds included monitoring wells DMW-I through DMW-7. Additional quarterly monitoring rounds were completed in March and June 2004, which also included monitoring wells DMW-8 and DMW-9. Those wells were installed during March 2004, at the locations shown on Figure 2, to assess possible contaminant migration downgradient of the former location of the waste oil tank. lowf 2.1 MONITORING WELL INSTALLATION Monitoring wells DMW-8 and DMW-9 were installed on March 4 and 5, 2004, by Gregg Drilling and Testing, Inc. of Martinez, California. Table 1 presents the monitoring well construction details, and Appendix A presents the boring logs and well completion diagrams for the installed wells. The well borings were advanced using a 10-inch hollow-stem auger. To evaluate lithology, drive samples were collected at five-foot intervals. The wells were predeveloped using a surge block prior to emplacement of the bentonite seal to ensure that the sand filter pack was solid and continuous. Development consisted of bailing, surging, and pumping until a minimum amount of sediment was ' observed in the discharged water, and the visual clarity approached 5 nephelometric turbidity units (NTU). The borings for DMW-8 and DMW-9 were advanced to a total depth of 70 and 90 feet bgs respectively. Monitoring wells were constructed of 2-inch-diameter Schedule 40 PVC screen and casing. 1 DMW-8 is screened between 60 and 70 feet bgs, and DMW-9 between 80 and 90 feet bgs. Surface *- completion for both wells consists of flush-mounted traffic vaults. The boreholes for DMW-8 and DMW-9 were advanced using hollow-stem auger drilling. To evaluate lithology, drive samples were collected at five-foot intervals. The samples were screened with a photo- ionization detector(PID)to aid in selection of samples for analysis. Five soil samples,three from DMW-8 and two from DMW-9, were submitted for analysis.The borings for DMW-8 and DMW-9 were advanced to a total depth of 90 and 70 feet bgs respectively. Monitoring wells were constructed of 2-inch-diameter Schedule 40 PVC screen and casing. DMW-8 is screened between 80 and 90 feet bgs, and DMW-9 between 60 and 70 feet bgs. Both wells were furnished with flush-mounted traffic vaults. After allowing two days for setting of grout, the wells were developed with a combination of bailing, swabbing over the k" length of the screen, and pumping until a minimum of 10 casing volumes of water had been removed and clarity achieved. 2.2 GROUNDWATER MONITORING The new wells were incorporated into the first quarter 2004 groundwater monitoring round, which was conducted on March 19, 2004, and the results presented in First Quarter 2004 Groundwater Monitoring Report, Former American Forest Products Stockton Facility, Stockton, California (URS, 2004). Second quarter 2004 groundwater monitoring was conducted on June 14, 2004,and the procedures and results are incorporated into this report. L Ti K:%Wprocess\22736\Arnerican ForestlWell Installation Report revOl.doc i