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• X11. ... ...- i1 `-_- �' __.... _ '> ; -, -' _ j , = ..� . V. . ;, +. - • • - f - . -CLEARWATER : G R O U P, ,. I N C: 2.2 -Monitoring Well-Installation - 'On March 31, 1995, the soil borings were,converted into monitoring wells with the- ' same designation.' All ,monitoring wells were constructed' of •2-inch diameter schedule.,40" PVC blank casing coupled to 0.02" inch slotted well screen.,` Each monitoring'well was completed at. 60 feet bgs; and screened from 40 to 60 feet bgs: The annular space was; filled with filter-pack sand to, one foot,above. the top of the slot#ed.-"well screen... ' The wells were sealed with two feet of bentonite pellets, extending from the top of the filter pack and the 'remaining annular space was filled with, neat 'cement. A traffic-rated road-box, was installed at grade:.surface. Monitoring welllocations are shown on Figure 2. 2.3 Monitoring'Well Development, Survey, Gauging and Sampling On, May -1, 1995, the elevation of the top-of-casing of the monitoring wells were Surveyed relative' to, a'pioject benchmark. 'The monitoring wells 'were gauged for depth to groundwater and inspected for . the-_.presence of separate-phase hydrocarbons.'. The wells were then developed by purging at least ten'saturated well �. volumes. 'Following.development, groundwater samples were collected- from the monitoring wells using dedicated polyethylene-bailers. Well gauging, purging.and sampling information is presented in.Appendix D. The sample 'containers were labeled, documented'on a chain-of-custody form, and placed in a cooler for transport to American Environmental Network, a DHS-certified laboratory located in Pleasant Hill, California. In accordance with the approved workplan, groundwater samples were analyzed for concentrations of TPHg and BTEX. , 3.0 RESULTS �. 3.1 Site Stratigraphy 1. Sediments encountered during drilling consisted predominantly of silts and sand, with lesser fractions of,fill. Except where replaced by imported fill, the uppermost horizon beneath the site consists,of°silt.'or silty sand. This unit extends from.near grade to between 20.5 feet from-ground surface'(in boring MW-1) to 31 feet in boring ' rMW-3. A •layer of,sand, ranging from approximately five to 11 'feet in thickness, is ` encountered.beneath the silt-in all three.borings." This layer "appears to thin towards the south. Interbedded silt and subordinate sand and silty sand are encountered below the apparently continuous sand,unitto the .total depth explored. Complete soil descriptions are presented ' in Appendix • C. Initial depth 'to ' groundwater in all four soil borings was in the vicinity,of 50 feet bgs. D-las PSA 3 May 25; 1995