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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 11 borings, unless casing is required, which will increase the boring diameter to 6 to 8 inches. Soil samples will be collected from borings using one or more of the following methods; a standard penetration test (SPT) barrel (split spoon sampler), Modified California sampler, Pitcher Barrel sampler, 101 mm Geobarrel, 134 mm Geobarrel, Shelby tubes, and grab samples of the cuttings. Downhole testing will be performed in some of the borings using geophysical and mechanical methods. This will involve sending a small probe down the hole and taking readings periodically with depth. The duration of investigation activities for the 167 borings will be up to: • 5 work days for each of 22 borings up to 50 feet deep, and • 13 work days for each of 145 borings 50 to 200 feet deep. All cuttings and excess drilling fluid will be contained in drums, large containers, or vacuum trucks, and disposed of offsite at an appropriate landfill. Recirculation tanks (55-gallon storage drums) will be used to settle drill cuttings from drilling fluid (drilling polymers and/or bentonite clay). Discarded soil samples will also be placed in the storage drums. Drums would be stored on site at designated staging areas outside of environmentally sensitive areas at any given soil investigation site for up to 4 weeks for environmental testing prior to landfill disposal. Following completion of soil investigation, holes will be sealed using cement-bentonite grout in accordance with California regulations and industry standards (Water Well Standards, DWR 74-81 and 74-90). 2.1.2 On-Land CPT Equipment Vehicles at each Impact Area during the investigation may include a truck- or track- mounted, 20 to 30-ton push-capacity CPT truck (see Figures 5 and 6) that is typically powered by a 400 to 550 horsepower diesel engine, a tractor-trailer lowboy truck (if a track-mounted rig is required), traffic control trucks, and a grout trailer. Additionally, up to 15 support passenger vehicles may be present. While this complete list of vehicles may be used, not all of them are necessary for every site. For example, many of the Impact Areas will likely not require a tractor-trailer lowboy truck or traffic control trucks.