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Aw, a 20 August 2009 AGE-NC Project No. 06- 1457 Page 6 of 7 out or draw in sediment from the filter pack and additional ground water evacuation (purging) with a submersible pump to finish the removal of fine-grained sediment. Developmental purging activities will be continued until field parameter (pH, electrical conductivity, and temperature) readings have stabilized andpurged water is visually sediment-free. Proposedwells will be surveyed relative to the closest City of Stockton benchmark by a licensed surveyor. 3 .4. GROUND WATER SAMPLING PROCEDURES Ground water sample collection will be performed in accordance with the EHD ' s Recommended Groundwater Sampling Guidelines, dated 15 February 1995 . 3 .4 . 1 . Static Water Level Measurements Before purging and sampling during ground water monitoring events, static water level will be measured using an electric water level indicator. Water level data will be recorded to the nearest 0.01 -foot from a reference point marked at the top of the PVC well casing. Before and after each use, the electric oil/water level indicator will be washed in an Alconox solution and rinsed with water. 3 .4.2. Well Evacuation Subsequent to measurement of depth to water and prior to sampling, wells will be purged using an inertia pump or submersible pump to ensure ground water samples are representative of the formation, rather than water standing in the well casing. Each well will be purged until: 1 ) a minimum of three casing volumes is removed from the well; and/or 2) the field-measured ground water parameters pH, temperature and electrical conductivity have stabilized. However, if a well is purged dry prior to evacuating three casing volumes, a ground water sample will be collected following 80 percent recovery of ground water level within the well or within 8 hours of well evacuation. Purge water, free-product, and decontamination water generated during the ground water sampling activities willbe contained in DOT-approved drums which will be appropriately labeled for storage. Drums containing purge water will be stored on-site pending appropriate removal and disposal. Advanced GeoEnvironmental, Inc.