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Additional Monitoring Wells Installation Work Plan PiWngton North America,Inc. April 18,2005 Page-2- j 4.0 FIELD AND ANALYTICAL METHODS This section includes a description of the proposed site preparation; drilling details; monitoring well design, surveying, and well development; and groundwater sampling and laboratory analyses. 4.1 SITE PREPARATION Monitoring well installation permits will be obtained from the San Joaquin County Department of Public Health Services, Environmental Health Department (PHS/EHD). Prior to initiating the fieldwork, boring locations will be marked with white paint and/or stakes and Underground Service Alert (USA) will be notified at least 72 hours in advance of the fieldwork to locate and identify underground utilities in the vicinity of the work area. However, because the proposed boring locations are on private property, utilities contacted by USA may not mark their lines past property boundaries and into the Site. Therefore, it is the responsibility of the property owner to locate and identify underground utilities in and near the work area. Condor will notify the PHS/EHD and the Regional Board of the installation schedule a minimum of 48.hours in advance of fieldwork. I Prior to conducting drilling activities, an on site tailgate meeting will be held with all drilling personnel and Condor representatives in attendance. A site-specific Health and Safety Plan will be discussed with and presented to all personnel for their signatures. 4.2 DRILLING DETAILS Two monitoring wells will be installed by a California licensed drilling contractor. The wells will be drilled using a hollow-stem auger method that is appropriate for the soils underlying the Site. The down- hole equipment will be cleaned between borings. Drill cuttings will be spread on the ground near each well. All drilling and well completion activities will be completed under the supervision of a California , Registered Geologist or Professional Engineer. Condor will prepare geologic and completion logs for each well. Drill cuttings for the monitoring well borings will be logged according to the Unified Soil f. Classification System(USCS), and soil samples will be collected every five feet to describe the lithology. Descriptions of soil types encountered and any other pertinent field observations will be recorded on boring logs. Completion details recorded on logs will include the type of screen and casing, depth intervals of the screen, blank casing, sand pack, bentonite seals and surface seals, and the quantities of materials added to the annular spaces. 4.3 MONITORING WELL DESIGN Each well site will be hand-augered to four feet below ground surface (bgs) before drilling to lessen potential for intercepting utilities. The monitoring wells will be drilled using 8-inch O.D., continuous- flight, hollow-stem augers. The augers will be steam cleaned before each boring is drilled. Each well will be drilled to 20 feet bgs. The monitoring wells will be constructed with ten (10) feet of 2-inch I.D., Schedule 40, flush-threaded, machine-slotted PVC screen (slot size 0.020). A flush-threaded PVC bottom cap will be placed at the bottom of the screen. Blank PVC casing will be installed above the screen to the ground surface. No glue or solvents will be used in the construction of the wells. i i ;1� CONDOR