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Additional Groundwater Investigation Report CSUS Multi-Campus Regional Center August 19,2003 Page 5 exception of CPT-5. CPT-5 was advanced through a concrete pad and the borehole diameter could not accommodate the grout collar. 3.21 Discrete Depth Groundwater Sampling During the April 2003 groundwater investigation, groundwater was first encountered in soil borings at depths ranging from 39.8 to 46 feet. Groundwater rose in the borings to a depth of approximately 38 feet. Discrete depth groundwater sample intervals were selected based on the results of the CPT boring logs. Three discrete depth groundwater grab samples were collected from borings CPT-4 and CPT-5; and four discrete depth groundwater grab samples were collected from borings CPT-6, CPT-7, and CPT-8. Two discrete depth groundwater grab samples were collected from a single depth interval from GP-10; a high sediment load in the initial groundwater sample prompted the collection of the second groundwater + sample in order to maintain sample integrity. The depth of each sample interval is'noted in Table 3, section 5.2. Groundwater samples were collected at discrete depth intervals using a Hydropunch@�type groundwater sampling system. A retrievable drill tip was advanced using 1.75-inch diameter hollow rods. A stainless steel filter screen was attached to the tip. At the desired sampling depth, the rods were retracted exposing the filter screen. Groundwater flowed hydrostatically from the formation into the filter screen. A small diameter bailer was then utilized to collect the groundwater sample through the"hollow rod. The groundwater sample was discharged directly from the bailer into laboratory supplied sample containers. All groundwater sample containers were sealed, labeled, and placed in a cooler chilled with ice and delivered under chain=of-custody procedures to.a California certified laboratory for analyses.The samples were analyzed using U.S. EPA Methods and California-approved methods. 3.3 LABORATORY ANALYSES Groundwater samples collected from the borings were analyzed for total petroleum hydrocarbons quantified as gasoline, kerosene, diesel, and motor oil (TPH-G, -K, -D, and -MO)"by EPA Method 8015m; for benzene, toluene, ethyl benzene, and total xylenes (BTEX) by EPA Method 8020; and for gasoline oxygenates/additives by EPA Method 8260B. Due to poor groundwater recharge, the following intervals contained insufficient sample for TPH-K, -D, and MO laboratory analysis: CPT-4 at 3842 feet, ` CPT-7 at .123-127 feet, and GP-10 (B) at 44 feet. The gasoline oxygenates/additives include methyl tertiarybutyl ether (MTBE), ethanol, tertiary-butanol (TBA), di-isopropyl ether (DIPE), ethyl tertiary- butyl ether (ETBE), tertiary-amyl methyl ether (TAME), EDB, and 1,2-DCA.-Excelchem Environmental Labs of Roseville, California analyzed the groundwater samples. 4.0 INVESTIGATION RESULTS The results of the groundwater investigation include field observations (CPT boring observations, visual inspection of groundwater samples, and detection of sample odors) and groundwater sample laboratory analytical results. 4.1 FIELD OBSERVATIONS Field observations included CPT boring observations, visual inspection of groundwater samples, and detection of sample odors, A thin layer of product was observed in the groundwater'sample collected from 40-44 feet bgs from CPT-8. Floating product or sheens were not observed in the groundwater samples collected from the remaining borings. A strong petroleum hydrocarbon odor, which decreased with depth, was noted in the groundwater samples collected from CPT-8.'A weak petroleum hydrocarbon odor was noted in the groundwater sample collected from CPT-5 at 38-44 feet bgs. Petroleum hydrocarbon odors were not noted in the groundwater samples collected from the remaining borings. CON©0R