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t e ; CDM Camp Dresser&McKee Inc. Mr.Mike Miller January 6,2000 Page 2 GeoEnvironmental and is included as Attachment A. The predominant soil types encountered during drilling were silty sands,silt,clayey silt,and silty clay. No groundwater was encountered during drilling. Probe Depth Title 27 specifies a multiple-depth probe system with a shallow probe installed 5 to 10 feet below ground surface,an intermediate probe located at half the depth of waste,and a deep probe located at the depth of waste. However,the number of probes required may be reduced if the depth to waste is less than 30 feet,or if site conditions do not warrant the installation depth criteria. The approximate ground surface elevation of the five relocated probes is between 30 and 39 feet mean sea level(MSL). The bottom of waste at the Austin Road Landfill is located at approximately 20 feet MSL,resulting in a target depth for the probes of approximately 10- 19 feet below ground surface(BGS). Table 1,Soil Gas Probe As-Built Construction Details, summarizes the surface elevation,depth,borehole construction,and screen intervals for each of the probes. Groundwater elevations in the vicinity of the probes are deep enough such that there is no danger of groundwater entering the probes. Table 1 Soil Gas Probe As-Built Construction Details Surface Soil Gas Elevation Total Depth Cement Bentonite Filter Pack Screen Probe feet MSL feet BGS feet BGS feet BGS feet BGS feet BGS SGP-3B 38 19 0-7 7-9 9-19 11-16 SGP-7A 33 10 0-3 3-5 5-10 5-10 SGP-8A 30 10 0-3 3-5 5-10 5-10 SGP-9A 34 17 0-5 5-7 7-17 9-14 SGP-10B 36 18 0-6 6-8 8-18 10-15 Notes: 1. BGS=below ground surface 2. MSL=mean sea level Probe Design The construction schedule of the soil-gas probes is illustrated in Figure 2,As-Built Gas Probe Detail. Each probe consists of a 1-inch,Schedule 40 PVC casing and contains a V/- inch O.D. teflon tube for gas sampling. The tube is suspended by two rubber stoppers located at the top and mid-length of the casing. The lower 5 feet of casing is slotted in order to allow gas to enter the sampling tube. The top of the casing extends approximately 2 feet above the ground surface and is protected by a steel standpipe and locking well cover.