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Additional Soil and Groundwater Investigation and Monitor Well Installation Report CSUS Multi-Campus Regional Center January 11,2002 Page 3 :'3.2 CPT PROCEDURES t � A Condor geologist was on site to supervise the work. Prior to commencement of fieldwork, a tailgate safety meeting was held and a site-specific.Health."and Safety Plan was discussed with, and presented to, 'all field personnel for their signatures. 'I The investigation included the advancement of four-CPT borings (CPT1, CPT2, CPT2-A, and CPT3) on } November 19 and 20, 2001 using a Gcoprobe®CPT system. The.boring locations are shown in Figure 2, ;Appendix A. Borings CPTi, CPT2, CPT2-A, and CPT3 were advanced to depths of approximately 91 ' feet, 81 feet, 81 feet, and 83 feet `below ground surface (bgs), respectively. The CPT borings were hydraulically advanced downward into the subsurface using an electric piezocone tip. Measurements of 'cone resistance, sleeve friction, and dynamic pore water pressure were measured at approximately one- .,inch intervals to provide a nearly continuous hydrogeologic log of the-subsurface. "The CPT cone and associated push rads were thoroughly cleaned before each boring was advanced using laboratory-grade, non-phosphate detergent and de-ionized water and double-rinsed with de-ionized�water. t `iUpon completion of the borings, the boreholes were backfilled with neat cement. . Difficulties were experienced in retrieving data from.depths below approximately 53 feet in borings CPTI and CPT2 on November 19; 2001. A replacement part shipped from the manufacturer was installed ort November 20, 2001. Boring CPT2-A'was advanced within one foot of the location of boring CPT2 and encountered the same data retrieval problems as experienced in the two previous boreholes. Boring CPT3 encountered similar data retrieval problems- No data was lost during the advancement of the borings; however, short intervals of data may'not accurately represent the subsurface soils. Representativesof the CPT equipment manufacturer stated that.similar data retrieval problems have occurred when advancing ` CPT borings in glacial till. The problems are usually caused by loading of the cone in dense soils, then the inability of the cone to "relax"to a normal state after passing from the dense soil to one that"-is not dense. The manufacturers representatives were not certain that was the cause of the problem at this site. Copies �"of the CPT boring logs are included in Appendix B. 3.3 DIRECT PUSH BORING PROCEDURES A Condor geologist was on site to supervise the work. Prior to commencement of fieldwork, a tailgate :safety meeting was held and a site-specific Health and Safety Plan was discussed with, and presented'to, :all field personnel for their signatures. i The investigation' included the advancement of three direct push Sam le'Point borings (SP-1, SP-2 and SP-3) to collect groundwater samples and four direct push soil borings (GP-6, GP-7, GP-8, and GP-9) to f collect soil samples on November 21, 2001 and December 11, 2001 using a Geoprobeg boring and 4 sampling system. The boring locations are shown in Figure 2, Appendix A. Borings GP-6, GP-7, GP-8, -and GP-9 were advanced to depths of approximately 56 feet, 61 feet, 61 feet;.and 61 feet bgs, t respectively. The direct push borings were hydraulically advanced using a 1.5-inch diameter conical bit. The bit and associated push rods were thoroughly cleaned before each borehole was advanced;;using { laboratory-grade, non-phosphate detergent and de-ionized water and double-rinsed with de-ionized water. Upon completion of the drilling and sampling, the boreholes were backfilled with neat cement. The cement was tremied into the boreholes to avoid bridging. 3.3.1. Soil Sampling The direct push borings were advanced to a depth of approximately 10 feet below apparent hydrocarbon contamination as.indicated by"staining, odor, or PID measurements. Soil samples were collectcd:from ' several sample depths in each boring. Sample depths are indicated on the geologic logs in Appendix B. C CONDOR