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Soil Investigations for Data Collection in the Delta Initial Study/Proposed Mitigated Negative Declaration 4 2.0 PROPOSED PROJECT DESCRIPTION The Proposed Project consists of both on-land and overwater soil investigations as well as several on-land geophysical studies located within the Study Area (Figure 2a-c). The on-land soil investigations will consist of the following: • 167 soil borings from 50 feet to 200 feet below ground surface; • 103 cone penetration tests (CPTs) from approximately 50 feet and 200 feet below ground surface; and • Up to 5 noninvasive geophysical survey investigation arrays on up to five Impact Areas within a location on Bouldin Island (see Figure 2b). The distribution of the various types of on-land soil investigations was determined to provide appropriate coverage to gain a preliminary understanding of the geological and geotechnical conditions in the Study Area. An effort was made to distribute soil borings at varying depths evenly throughout the Study Area; the location of CPTs was determined to provide supplementary subsurface information to complement the soil borings. Geophysical surveys can collect data to provide a more robust preliminary interpretation of regional subsurface conditions and identify anomalous features such as abandoned oil and gas wells or unmarked utilities. The planned geophysical surveys will be used as a test program to determine if these noninvasive surveys are appropriate for future use in other regions of the Delta, thereby reducing the potential need for soil borings or CPTs in certain areas. Overwater soil investigations will consist of 57 soil borings up to 200 feet below the slough or river bottom (measured at the mudline). Table 1 includes the Proposed Project’s maximum total duration for each type of on- land soil investigation and overwater soil investigation that requires large equipment. Additional details regarding Impact Area-specific durations and equipment needed for each type of soil investigation are provided in the descriptions below. Table 1: On-Land Soil Investigation Primary Equipment and Duration Activity Equipment Anticipated Duration Soil Borings Up to 8 Drill Rigs 6 months CPTs Up to 3 Truck-Mounted CPT Rigs 6 months Geophysical Surveys Geophysical equipment (depending on method) 2.5 months Overwater Borings Up to 6 Drill Rigs (located on Boats or Barges) 3 months