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APPENDIX A BROWN AND CALDWELL STANDARD FIELD PROCEDURES The following is Brown and Caldwell's standard field procedures for borehole drilling, groundwater monitoring well installation. groundwater sampling and sample handling BOREHOLE DRILLING Boreholes are drilled by a licensed drilling subcontractor, using a truck-mounted drilling rig equipped with nominal 8-inch-diameter hollow-stem augers During drilling, soil samples for lithologic identification and possible laboratory analysis are collected every five feet in the borehole Boreholes are drilled to a predetermined depth below the ground surface or are terminated when two consecutive readings indicating hydrocarbons are not present in the soil are collected or groundwater is encountered Borehole depths are based on site conditions, including but not limited to conditions such as depth to water, topography, and depth to bedrock To prevent cross contamination during drilling, all equipment is steam cleaned prior to and between use at each borehole GROUNDWATER MONITORING WELLS Monitoring Well Drilling, Groundwater monitoring wells will be drilled by the method described in the section entitled Borehole Drilling, with the exception that they will be drilled to a depth of 15 or 20 feet below the water table or piezometric surface, depending upon known conditions and upon unanticipated conditions encountered during drilling. Soil samples will be collected every five feet the entire depth of the borehole for lithologic identification, field screening, and possible laboratory analysis The borehole will then be completed as a monitoring well by the method described below Monitoring Well Completion. Groundwater monitoring wells will be completed with PVC screen and casing On-site monitoring wells will be completed with flinch-diameter PVC screen and blank casing, while off-site wells will be completed with 2-inch-diameter PVC A PVC cap will be installed at the bottom of each well. The well screen typically will be 0 020-inch slotted flush-threaded PVC, extending from a depth of approximately 15 or 20 feet below the water table or piezometric surface to 5 to l0 feet above The well design is intended to accommodate seasonal water-level fluctuations within the slotted interval The well design may be modified in the field during the drilling operation, depending upon conditions encountered during drilling In no case does the monitoring well penetrate clay zones greater than 5 feet thick, which might allow downward migration of contaminants into lower water-bearing zones Blank casing extends from the top 26404ZEPORTS12640-01 WP