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Limited Phase If Site Assessment Work Plan 239 West 11 1" Street Tracy, California Project No. 2E-1108004 Page 4 3.1. Soil Sampling Methods 3.1.1. Direct -push Soil Sampling Methods Direct -push soil sampling techniques will be used to obtain soil samples to assess the potential presence of impacted native soil possibly from the former gasoline tank on the Site or impacts from adjacent properties to the south. Giles will complete two (2) direct - push soil borings in native soil adjacent to southern property line and advanced to a common termination depth of 15 ft. bgs. Giles proposes that up to three (3) additional Geoprobe® soil borings be completed along the eastern perimeter of the building or in a triangular pattern, centered on the former UST basin if located by the magnetometer, and advanced to 15 ft. bgs if PID, visual, or olfactory evidence of soil impact is observed in soil samples collected from the 10 -foot triangular grid. The proposed direct -push soil boring locations are shown on Figure 2. The direct -push soil samples will be obtained continuously from each boring to their respective termination depths. Discrete soil samples will generally be retrieved using a 1.5 -inch outside diameter (OD), 30 -inch long solid barrel sampler, equipped with a 24 - inch long acetate sample liner (1.15 inch OD). In some cases samples will be collected using large bore samplers equipped with 48 -inch acetate sample liners. For sample collection, the sampler will be connected to the leading end of a probe rod and hydraulically driven into the subsurface. Additional rods will be connected in succession to advance the sampler to depth. The sampler will remain sealed by a piston tip, held in place by a stop -pin at the trailing end of the sampler. Once the sampler reaches the top of the desired sampling interval, the stop pin will be removed and the sampler will be advanced 24 inches (or 48 inches for the large bore sampler) to obtain the sample. The sampler will then be retrieved from the hole for sample collection. Once the sampler is brought to the surface, the acetate liner filled with material will be removed from the sampler and soils are transferred from the liner directly into appropriate laboratory -supplied sample containers and field classified and logged. The sample will be handled using clean/new latex gloves. The gloves will be changed between successive samples. The cutting shoe at the tip of the sampling device will be cleaned and decontaminated between successive samples. The entire sampler assembly including the core barrel and cutting shoe will be cleaned and decontaminated between successive borings. Soil samples will be classified in the field in general accordance with the Unified Soil Classification System (USCS) American Society for Testing and Materials (ASTM D- 2488-75). The soil classifications will be documented on the Records of Subsurface Exploration forms. GILES ENGINEERING ASSOCIATES, INC.