WORK PLANS - Laserfiche WebLink

Home Browse Search

20 December 2000 AGE-NC Project No. 95-0100 Page 6 of 8 Following sample collection, each preserved sample sleeve will be labeled with the boring location, depth, time, date and sampler's initials. Appropriately sealed and labeled samples will be placed in a chilled container under ice and transported under chain-of-custody procedure to a DHS-certified laboratory. Soil samples will be analyzed for methods described in Section 3.2.1. The monitoring well soil pilot boring will be advanced a truck-mounted drill rig equipped with hollow-stem augers. The boring for monitoring wells be advanced utilizing 8-inch augers. Proposed monitoring well designs are illustrated in Figures 3 and 4. Following completion of the soil borings a 2-inch diameter Schedule 40 PVC 0.02-inch slotted well screen and casing will be installed. A 20-foot section of well screen will be installed from a depth of approximately 40 feet to 60 feet bsg or a 5-foot screen will be installed from a depth of approximately 80 feet to 85 feet bsg. The casing, filter pack and well-seating 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#3 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 or bailed to assist in settling the filter pack. Additional sand will be added if settling occurs. A nominal three- foot bentonite seal will be placed above the filter pack. The bentonite chips will be hydrated with five gallons of potable water. The bentonite chips will be allowed to hydrate for a minimum of one- half hour prior to grouting. The remaining annular space will be filled to well box base at the ground surface with a cement grout. The grout mixture will consist of Type I/H portland neat cement and not more than 10 gallons of water per 94-pound sack of cement. The grout will be placed over the bentonite as an annular, sanitary seal. Grouting procedures will be inspected by PHS-EHD personnel. A traffic-rated well box will be installed over the well tops and maintained in accordance with well code regulations. Following completion of the monitoring wells, well top elevations and locations will be surveyed by AGE personnel. 4.2. WELL DEVELOPMENT Development will consist of a combination of bailing to remove the major portion of fine-grained sediment from inside the well, surging to flush out or draw in sediment from the filter pack, and additional bailing to finish the removal of sediment. Well development activities will be continued until field parameter(pH, electrical conductivity, and temperature)readings have stabilized. Ground water generated during the water well development activities will be contained in DOT-approved drums which will be appropriately labeled for storage. Drums containing water will be stored on-site pending appropriate removal and disposal.