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30 November 1998 AGE-NC Project No. 98=0520 ' Page 7 of 9 ' acid as sample preservative. Samples for TPH-mo analysis will be collected in I ab oratory-suppli ed one-liter glass containers. The labeled vials will be placed in a chilled container under ice and transported under chain-of-custody to a DTSC-certified laboratory. 3.4. MONITORING WELL INSTALLATION PROCEDURES The monitoring well borings will be completed using hollow-stem auger drilling techniques. Relatively undisturbed soil samples will be collected at five-foot intervals in each of the borings using a California modified split-spoon sampler fitted with 2-inch diameter, 6-inch long brass sleeves. Soil sample handling will be consistent with the procedures presented in Section 3.2. Following completion of drilling the boring, A-2-inch diameter Schedule 40 PVC 0.010-inch slotted well screen and casing will be installed. A 15-foot section of well screen will be installed in each ' well, extending approximately 10 feet below and five feet above the top.of the ground water table. The casing, filter pack and sealing materials will be placed into the borehole through the interior of . the hollow-stem augers. After installing the well casing,filter pack material consisting of pre-washed ##2/12 Lonestar.sand will be added from the bottom of the borehole to approximately two feet above the screened interval. Following placement of the filter pack, the well will be surged to assist in ' settling the filter pack. Additional sand will be added if settling occurs. An approximately two foot bentonite seal will be placed above the filter pack to minimize the ' potential of grout penetration into the screened section of the well. The bentonite seal will be formed by pouring'bentonite chips into the annulus and allowing them to settle on the filter pack. Bentonite chips will be hydrated using five gallons of dater. The bentonite chips will be allowed to hydrate rfor a minimum of one-half hour prior to grouting. ' The remaining annular space will be filled to the ground surface with a cement grout. The grout mixture will consist of Type 1/11 portland neat cement and not more than 6 gallons of water per 94-pound sack of cement. The grout will be placed by pumping through treminie pipe. Grouting ' procedures will be inspected by PHS-EHD personnel. Following completion of the monitoring wells, well elevations and locations will be surveyed by a ' Cal iforrila-licensed surveyor. ' 3.5. WELL DEVELOPMENT Development will consist of a combination of bailing to remove the major portion,of fine-grained Advmiced Geo Environmental;Inc.