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Landfill Gas Migration Monitoring Well Installation Report October 2009 Foothill Landfill Project No. 03160203 2.2.1 Soil Logging and Sampling The soil cuttings were logged by Vector personnel while drilling, according to the Uniform Soils Classification System Description and Identification of Soils Visual- Manual Procedure ASTM Designation D2488. The soils underlying the FSL are part of the Pliocene age (2 to 5 million year) Laguna Formation and the Miocene age (5 to 24 million years) Mehrten Formation. Because of the relatively old age of this material it was sometimes classified as various types of sedimentary rock (sandstone, siltstone etc). The boring logs for all of the LFG wells are included in Appendix A. Earth materials encountered during drilling included mostly gravel and cobbles in the upper portions of the borings in the northern portion of the site. This was underlain by various amounts of sand, sandstone, siltstone, silt, sandy clay and clayey sand. No Standard Penetration Test (SPT) samples were taken, and Vector personnel had to use judgment and driller feedback to determine the approximate depth that the soil cutting samples originated from. Photographs showing the locations of the landfill gas probes and various drilling/installation activities are attached in Appendix B. 2.2.2 Landfill Gas Migration Monitoring Well Construction The LFG monitoring probes are nested with three casing strings installed in the same borehole (Figure 3). The wells were constructed based on the materials specified in the Plans and Specifications, and the construction sequence was as follows: • The LFG monitoring probe pipes, which were constructed using 3/4-inch diameter, high density polyethylene (HDPE) continuous length pipe, were measured and cut in the field by LFG Control personnel. • Perforations were drilled in the field by LFG Control personnel using a 1/8- inch bit. The perforations were spaced one-inch apart with alternating holes offset 90 degrees in accordance with the project Plans and Specifications ® (Photograph 25, Appendix B). Vector Engineering, Inc. • 143E Spring Hill Drive•Grass Valley, CA 95945•(530)272-2448 3