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Oct-08-01 04: 13P . • P. 10 As shown in Figure 2,Sequence 1 and Sequence 2 data will be collected using direct- h methods at 13 locations(1 through 13)and using hand-augering methods at 6 locations (HA-1 through HA-6). Direct-push methods,which will be performed using either Cone Penetrometer Testing(CPT)equipment or Geoprobe equipment,will be used at those locations capable of supporting a CPT truck or Geoprobe truck and outside the ecologically sensitive potential wetlands area. CPT methods will be used at all direct-push locations except those along the existing SFPP pipeline where access is limited preventing CPT use. CPT will be performed at nine locations(5 through 13),and Geoprobe methods will be used at four locations(1 through 4). Hand-augering equipment will be used on the peninsulas of pre-existing oil and gas exploration drilling mud wastes to: (1)alio*access to unconsolidated sediments composed of drilling mud wastes that are soft and unstable due to shallow water table conditions and(2) limit any impacts to an ecologically sensitive potential wetlands area. Data collected during Sequence 1 will be used to select depths for soil and grab groundwater samples for laboratory analysis,which will be collected in Sequence 2. Sequence 2 will include advancement of an additional boring(adjacent to the Sequence 1 boring)for soil and grab groundwater sample collection. 3.2.1 Sequence 1: Initial Lithologic Profiling Direct-Push Borings using CPT Methods. The nine CPT borings(5 through 13)will be performed to continuously log subsurface lithology as described in the April 13,2001,Work Plan,except that the locations will be modified to those shown in Figure 2;and the depths will be modified to those shown in Table 1. The depth of the investigations in the main part of the source area will be limited to 20 feet to minimize the potential for vertical cross- contamination to deeper zones. The depth of four CPT investigation locations on the perimeter of the source area are maintained at the original 50-foot-bgs depth because the potential for cross-contamination on the perimeter of the source area is considered to be minimal. The CPT tool will be equipped with an ultraviolet-induced fluorescence(UVIF) probe to continuously screen for the relative presence of petroleum free-phase hydrocarbons in the subsurface as described in the April 13,2001,Work Plan. The four deeper CPT borings will be advanced beyond 50 feet if the UVIF data continue to detect the presence of petroleum hydrocarbons. The nine shallower CPT borings will not be advanced beyond 20 feet if the UVIF data continue to detect the presence of petroleum hydrocarbons to minimize the potential for vertical cross-contamination to deeper zones,as mentioned above. Direct-Push Borings using Geoprobe Methods. The four Geoprobe borings 1 P g ( through 4)will be advanced to continuously log subsurface lithology where CPT access is not possible along the existing SFPP pipeline. These borings will be advanced to 20 feet bgs. Soils will be continuously logged to identify structural features that may be conducive for free-phase product accumulation and screened for the presence of petroleum hydrocarbons in the subsurface. Soil will be visually logged,and headspace will be screened using a photoionization detector(PID). Hand-Auger Borings. The six hand-auger borings (HA-1 through HA-6)will be advanced to continuously log subsurface lithology where CPT and Geoprobe access is not possible due to soft conditions and where the low impact of hand augering is more appropriate given the ecologically sensitive potential wetlands conditions. These borings will be advanced to scon.nw3209,00cro12430001 s