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=� CDIM Standard Operating Procedure �W10 V 0 2.1 Subsurface Soil Sampling Rev.1 10/23/2020 simultaneously being pushed down by the operator. During auger advancement and sample collection, observations of the geologic features should be recorded in the sample log or field log. The operator should stop advancing the auger when the top of the designated sampling interval has been reached, in order to remove the auger from the hole and decontaminate it prior to sampling. Once the auger is prepared for sampling, it is driven through the sample interval, and the soil sample collected into the appropriate container. 3.4 Split-Spoon Methodology Split-spoon samples for chemical analysis are usually collected in brass, plastic, or stainless steel sleeves. The types, dimensions, and number of sleeves to be used, along with the length and type of sampler, will be stated in the project work plans. Before collecting each split-spoon sample, the borehole is advanced to the desired depth or target horizon where the sampling run is to begin and the drill bit or plug is removed from inside the drive casing or augers. Then the split-spoon sampler is prepared by placing the appropriate sleeves within the split-spoon sampler or "barrel." The split spoon sampler is held together by a rear (in the upper position when in drive position) threaded collar and front drive shoe (lower position when aligned for driving into soil); both of which are screwed on to the respective ends. The split-spoon sampler, lined with the sleeves, is then connected to the drill rod string, or a wireline sampling string, by the driller. After the drill rod or wire-line is lowered to the desired sample depth the driller drops a 140 or 340 pound hammer, depending on the size of the sampler, onto the sampler to drive it into the undisturbed soil below the bottom of the borehole. Generally the hammer is repeatedly dropped 30 inches until the sampler is driven the desired distance. However, there are two exceptions to this setup: 1) when the rig is equipped with an automatic hammer, which approximates the same impact and drop, and 2) when 5-foot samplers or"core barrels" are used, the rig exerts a combination of rotation and downward pressure on the core. The drilling geologist counts the number of hammer blows per 6 inch drive length and records that number on the boring log as the "blow count". The blow counts give a relative measure of soil resistance and strength; however, true soil testing for engineering purposes is collected with a "standard penetration test" split spoon or SPT. The SPT is 18 inches long, and has a 2 inch outside diameter, and a 1.5 inch inside diameter core barrel. The SPT is used occasionally for environmental sampling but is much more common in the geotechnical sampling arena. The "California modified SPT" split spoon is likely used for environmental sampling, is 18 inches long, has a 2.5 inch outside diameter, and 2 inch inside diameter. Next, the drill rod or wireline sampling string is pulled up from the bottom of the borehole and the sampler is removed. To extract the sample from the split-spoon sampler, the driller removes the drive shoe and rear collar from the sampler and opens the split barrel. The driller then places the soil-filled sleeves on the drilling geologist's table, indicating which end of the drive is the top and which is the bottom. After extrusion, the driller will insert new, steam cleaned or washed sleeves into the sampler, which is then lowered back into the borehole. Additional inner rods and outer drive casing can then be attached and the process is repeated until the desired depth is reached. Continuously repeat this sampling procedure until reaching the bottom of the borehole and/or the last sample has been collected as specified in the work plan. Prior to or during sampling, record the type of sampler assembly and hammer weight on the appropriate forms, as described in the Lithologic Logging SOP 15.1. To minimize off-gassing 4