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August 11, 2000 A-1 003-7170 APPENDIX A Monitoring Well Installation and Sampling Procedures The following is a summary of monitoring well installation, development, survey, sampling and disposal procedures that will be followed at the site. Permitting and Health and Safety Plan Appropriate monitoring well installation permits will be obtained from the San Joaquin County Public Works Department. Prior to initiating the field activities for monitoring well installation, monitoring well locations will be marked on the site with white paint and Underground Service Alert (USA) will be called to clear the monitoring well locations of the utilities. A health and safety plan will be prepared prior to initiation of field work. Golder personnel and subcontractors working on site will be provided with a copy of this health and safety plan. A health and safety meeting will be held prior to initiation of work. Drilling of Soil Borings The soil boring for the monitoring well will be drilled using a drill rig equipped with 8-inch hollow stem augers. The depth of each boring will be determined in the field, however we estimate total depth of the boring to be 80-feet bgs as noted in Sections 2.2 and 3.1. Soil samples will be collected at minimum five-feet intervals for logging purposes. Soil samples will be collected every five feet within each borehole and will be logged by a qualified Golder engineer or geologist using the Unified Soil Classification System. Each soil sample will be collected by driving a modified California sampler or similar sampler lined with sampling sleeves, into the soils ahead of the drill bit. Monitoring Well Construction The monitoring well will be constructed with two-inch flush-threaded schedule 40 PVC casing with an estimated screen size of 0.020 inch factory slots. Sand filter packs will extend approximately two feet above the screen and consist of clean washed #2/12 sand, or equivalent. Screen intervals will be as described Section 2.2 and 3.1. A two foot bentonite seal will be placed above the sand pack. Following hydration of the bentonite pellets, the borehole annulus of the monitoring well will be sealed with bentonite chips. The seal will be placed by tremmie methods. The bottom of the auger will be maintained below the bentonite seal during placement as appropriate. A flush mounted traffic rated boxes with bolts will be installed above the monitoring well at the ground surface. Expansion type or an equivalent locking cap will be placed on the PVC casing. Monitoring Well Development The bentonite seal in the monitoring wells will be allowed to set a minimum of 48 hours prior to development. Prior to development the static water level and total depth of the monitoring well will be measured using an electronic sounder and recorded to the nearest 0.01 feet. The monitoring well will be developed with a mechanical surging devise (surge tool) and bailers using a development rig, or equivalent. The pH, temperature, conductivity and turbidity of the water will be measured and ROO-37.doc Golder Associates