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Cecchm Cecchuu, and Crovannoni, Fueling Island Soils encountered in the boring consist of interbedded fine-grained materials ranging from silt to sand to the depths explored. From the surface, the soils consist of fill composed of silt to a depth of about four feet below ground surface (bgs) Beneath the fill, silt (ML) was encountered to a depth of about 19 feet bgs Medium-gramed sand (SP) was encounter between 19 feet bgs and 23 feet bgs Silt (ML) was encountered between the depths of 23 feet bgs to 65 feet bgs A zone of hard silt was encountered at 39 feet bgs Medium-gramed poorly graded sand (SP) was encountered between 65 feet bgs and 69 feet bgs with increasing amounts of interbedded silt occurring with depth Silt (ARL) was encountered below this depth to the bottom of the hole Detailed soil descriptions are given on the boring log presented in Appendix A 2.2 Mi onntoHng WeD Constar ueflon After the completion of the exploratory drilling, the wells (consisting of two-inch diameter schedule 40 PVC casing) were constructed in the borehole The two wells were nested with VP-1 installed above the screen interval of UST-5 Ground water monitoring well UST-5 was constructed with twenty feet of 0 02-inch maclune-slot screen installed between the depths of 54 5 feet bgs and 74 5 feet bgs Blank casing was installed above the screened interval to the surface. The annulus between the screen casing and the a borehole was filled with a No. 3 aquarium sand to a depth of 53 feet bgs Approximately 12 feet of bentonite seal was placed above the sand pack by adding bentonite pellets and hydrating with water The bentomte seal was approved in the field by the SJCHSD inspector following a test to hold water for a least ten minutes The vapor well VP-1 was installed above the bentonite seal with a screen interval from 30 feet to 40 feet bgs and No. 4 sand was added to a depth of 28 feet bgs. Bentonite pellets were placed above the sand pack and subsequently hydrated A seal consisting of Portland Cement, was tremied to within about a foot of the top of the well casings A traffic-rated vault box was installed at the surface to protect the wellheads Each wellhead was capped with a lockable expansion plug Well construction details are illustrated on the Boring Log and Well Completion Summary in Appendix A 2.3 WeR IIDeveRopmentl On June 20, 1996, ESE personnel returned to the site to supervise development and purging of the wells by the subcontractor Automated Environmental Services (AES) UST-5 was developed by surging and removing fines using a surge block and water F 169254WUQM%RPT 3 Environnnental Science h Engineering, Inc