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Landfill Gas Migration Monitoring Well Installation Report October 2009 <br /> North County Landfill Project No. 03160203 <br /> is Manual Procedure ASTM Designation D2488. The soil boring logs for all of the <br /> LFG wells are included in Appendix A. Soils encountered during drilling included <br /> mostly hard sandy clay and very dense clayey sands, and were relatively slow to <br /> drill. No Standard Penetration Test (SPT) samples were taken, and Vector <br /> personnel had to use judgment and driller feedback to determine the approximate <br /> depth that the soil cutting samples originated from. Photographs showing the <br /> locations of the landfill gas probe locations and various drilling/installation <br /> activities are attached in Appendix B. <br /> 2.2.2 Landfill Gas Migration Monitoring Well Construction <br /> The LFG monitoring probes are nested with three casing strings installed in the <br /> same borehole (Figure 3). The wells were constructed based on the materials <br /> specified in the Plans and Specifications, and the construction sequence was as <br /> follows: <br /> • The LFG monitoring probe pipes, which were constructed using 3/4-inch <br /> diameter, high density polyethylene (HDPE) continuous length pipe, were <br /> measured and cut in the field by LFG Control personnel. <br /> • Perforations were drilled in the field by LFG Control personnel using a 1/8- <br /> inch bit. The perforations were spaced one-inch apart with alternating holes <br /> offset 90 degrees in accordance with the project Plans and Specifications <br /> (Photograph 13, Appendix B). <br /> • For proper identification during construction, the tops of the probe pipes were <br /> painted as follows to indicate depth: yellow for the deep probe pipe; blue for <br /> the intermediate probe pipe; and red for the shallow probe pipe. <br /> • Each probe was completed with two 2-foot long rebar weights secured to the <br /> bottom of the probe with tie wire. Each probe also had a PVC end cap secured <br /> with stainless steel screws. <br /> • After drilling was completed, the total borehole depth was measured in the <br /> presence of Vector and EHD staff. <br /> Vector Engineering, Inc. • 143E Spring Hill Drive•Grass Valley, CA 95945•(530)272-2448 <br /> 3 <br />