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31 LIGHT, AIR & SPACE CONSTRUCTION ENVIRONMENTAL,SERVICES COMPANY State Contractor's License Number 445403 State EPA .A.Number 04072 The boreholes will be logged using the Unified Soil Classification System under the supervision of a professional geologist. Additional iithologic information may be collected to describe the subsurface geology. The soil samples will be collected at five-foot intervals, at intervals of obvious contamination and at stratigraphic features of interest. Soil samples will be field screened with a portable photoionization detector (PID) for fuel hydrocarbons vapor and staining. Samples showing elevated PID readings will be selected for chemical analysis. If field screening is inconclusive, soil samples will be. selected based upon possible staining, site stratigraphy and near the occurrence of groundwater. Upon completion of the borehole drilling and collection of soil samples, each borehole will be converted to a groundwater monitoring well using the procedures discussed below. Boring drill cuttings will be placed into closed top steel drums and placed at the Client-designated location. 4.0 Groundwater Monitoring Well Installation and Sampling 4.1 Monitoring Well Design and Installation Three monitoring wells will be construction using threaded Sch. 40 PVC casing; glues will not used. The slotted interval will use a 0.020-inch slot and the annular space around the slots will be backfilled with 2/12-size (or equivalent) sand pack. Previous experience has shown this to be a reliable well design in fine grained and stratified depositional environments in this area. Final well design will be modified to the site-specific conditions encountered in the borehole during drilling. Once the aquifer strata are defined, the casing will be lowered to the bottom of the borehole, leaving a short slotted sand pack interval above the occurrence of groundwater to observe for floating product. The sand pack will be placed to a point about two feet above the slots. A bentonite seal will be placed atop the sand pack, and a cement grout seal (cement mix witnessed and approved by the EHD representative in the field prior to sealing) will be placed atop the bentonite using a tremie line, filling from the bottom to top of the borehole. A traffic, rated well head access box and security device will complete each well. i 4.2 Monitoring Well Head Survey_ All wells will be scheduled for a location and elevation survey to a known datum. The well survey will also be performed so that well location and elevation are plotted for later data i inclusion into the regulatory reporting database. 1 4.3 Monitoring Well Sampling -Wells The wells will be developed and then purged and sampled (48) hours after development. Each I monitoring well will be purged using calculated well volumes based upon the depth to water in a each casing. Depth to groundwater measurements will be made to the nearest one-ane hundredth of one foot, and also checked for the presence of separate phase product. As each purge volume is removed, measurements of pH, electrical conductivity, turbidity, dissolved oxygen, salinity and temperature will be taken until these parameters stabilize over two I measurements, which is interpreted to be aquifer water entering the casing. The well will be allowed to stabilize to about 80%of its initial water level before sampling. i Page 3 Of MAIN OFFICE - 1707 LITTLE ORCHARD STREET, Surm A - SAN JOSE-CA-95125 MAILING ADDRESS•P.O.Box 36303•SAN JOSE•CA•95158-6303 • 408/979-0661 OFFICE-408/979-0621 FAX-408/640-2899 CELL PHONE-DOUTHUME0a LIGHTAIR.ANDSPACE.COM E-MAIL. GENERAL AND ENGINEERING CONTRACTOR-HAZARDOUS SUBSTANCE REMOVAL CONTRACTOR'SITE ENVMONN ENTAL ASSESSMENTS WETLAND AND RIPARIAN HABITAT-ASSESSMENT-DESIGN-RESTORATION-CONSTRUCTION-MITIGATION MOMTORING i