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1 <br /> Wright Environmental Services, Inc. <br /> Monitoring Well Construction <br /> 1. The proper permits will be obtained from the appropriate agency or water <br /> district, scheduling a Well Inspector as required to be present to witness the <br /> installation of the annular seal. borings will be drilled with a continuous-flight <br /> hollow-stem auger of nomin 8 inches utside diameter (to leave 2-inch annular <br /> space for well construction). A augers will be thoroughly steam-cleaned prior to <br /> arriving at the site. The augers will be steamed cleaned between borings at a location <br /> well away from the proposed borings or adequate clean auger will be available to <br /> complete all of the wells without reusing auger sections. <br /> 2. The borings will be advanced to the uppermost water bearing zone (or a depth <br /> of 45 feet if a saturated zone is not encountered and in absence of other exploration <br /> depth specifications). If a saturated zone is encountered, the boring will advance no <br /> further than 15 feet below first encountered groundwater or 5 feet into the <br /> underlying clay aquitard. If entered, a seal will be placed in the overdrilled portion <br /> of the aquitard. <br /> 3. Duringontamihe at d soilling illsr ] <br /> drill ngmucklon and rine wates will r <br /> e on site to contain <br /> potentially to minimize surface <br /> potentially <br /> contamination. <br /> 4. Where borings are completed as groundwater monitoring wells, 2-inch ID <br /> schedule 40 PVC blank pipe will be used. Well screen selection will be 2 inch ID <br /> Schedule 40 PVC pipe with 0.020 inch machine slot (in absence <br /> s will not <br /> specifications). Sections will be threaded and screwed flush together; glue <br /> be used. Screens will extend 3-5 feet above first encountered groundwater. The <br /> annulus of the perforated section will be packed with clean #3 or #14 Monterey Sand, <br /> Lonestar 2/12 Sand or equivalent, to a level about 2-feet above the screen interval <br /> (field experience has shown this monitoring well design has worked well in <br /> stratified alluvial and fine grained environments; if special well designs supersede <br /> this design, a specification will be attached). <br /> Final well design will be adjusted in the field to site specific subsurface conditions <br /> observed in the borehole, and well screens or slots will be placed so as not to <br /> interconnect two possible aquifers or uncontaminated vadose zone strata. Screens <br /> will extend a nominal length (up to 5 feet) above first encountered unconfined <br /> groundwater for floating product detection where needed. A 1-2 foot thick bentonite <br /> seal will be placed on top of the sandpak. A cement grout annular seal which <br /> extends to the surface will be placed by tremie line from the bottom to top of the <br /> remaining annular space above the bentonite. Sealing can be modified as regulatory <br /> input requires. <br /> 6. The top of the well casing will be locked to prevent contamination and <br /> tampering. ., An-above-grade or-at-grade well completion will depend upon well <br /> location. At-grade completions require traffic rated boxed set in concrete or cement <br /> grout just above grade. Above-grade completion will require a 6-inch diameter <br /> locking, steel protective "stovepipe" casing and a Christy, or equivalent, traffic box <br /> and concrete pad and surface poles or barriers to mark the location. <br /> WES Sampling Protocols <br /> last rev. 5/96 Page 4 <br />