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CA ARNG Field Quality Assurance Project Plan i 4.0 DRILLING METHODS 4.1 Permitting All necessary permits will be obtained from appropriate CA ARNG personnel and/or other local agencies personnel prior to commencement of any drilling operations, including construction, repair, or destruction of wells. 4.2 Cone Penetrometer Testing 4.2.1 The CPT direct push technique is a rapid method for characterizing subsurface conditions to depths of 100 feet or greater. In addition to characterizing subsurface geology, CPT has been modified to allow for collection of soil vapor, soil, and groundwater samples. The CPT assembly consists of a small diameter, instrumerited probe (the penetrometer) with an attached string of sounding rods, electronic cables, a hydraulic ram, and a computerized acquisition and display system. The assembly and support equipment is typically mounted on a CPT truck (e.g., a 20 -ton rig), which is mobilized to the designated sampling location. The test involves hydraulically pushing the probe into the ground while the computer system analyzes the soil response to penetration. Soil resistance, acting on the tip and along the sides of the penetrometer, is measured during penetration. The hydraulic ram is used to push the rod string and penetrometer into the ground using a specially designed truck that can deliver up to 20 tons of force to the rod. Electronic signals -from the penetrometer sensors are transmitted by -a cable, strung through the hollow sounding rods, to the data acquisition/display computer system at the surface. The total depth sounded at each location will be determined jointly by the field geologist and the CPT analyst based on the geologic profile encountered in the hole. } 4.2.2 Measurements are made in S centimeter depth increments and real-time data as well as graphs (i.e., depth vs. tip resistance and depth vs. sleeve resistance) are available immediately after soundings. The field geologist will collect the real-time data, complete a CPT log data sheet (Figure 4-1 at the end of the section), and keep a daily log of events and observations in a field notebook. 4.2.3 Before initiation of the testing, the field geologist and the selected subcontractor will conduct CPT adjacent to existing monitoring wells or borings to compare and calibrate the penetrometer sensor response to the known site-specific lithology. This calibration will consist of a comparison between the logs generated by CPT and other drilling methods. It will also allow for enhanced geologic interpretation ,through cross-section generation using both types of logs. This comparison provides control for the CPT data so an accurate evaluation of the subsurface can be made. 4.3 Hollow -Stem Auger Drilling 4.3.1 The hollow -stem auger (HSA) drilling technique is used for collection of soil samples in the vadose zone for HydroPunchO groundwater sampling. It is also used when groundwater monitoring wells are to be completed in the saturated zone. The HSA technique is commonly used for both vertical and slant soil boring investigations. No drilling fluids or lubricants are used, minimizing the potential for cross contamination or infiltration of materials into the formation. 4.3.2 The HSA technique involves constructing a borehole by simultaneously rotating and axially advancing the auger column into unconsolidated or poorly consolidated formations. As the augers are rotated and advanced into the ground, they act as casing to stabilize the borehole. The pilot bit and teeth on the auger head drill into the soil and direct the cuttings to the auger flights. As the augers are rotated the cuttings are brought to the surface by moving along the continuous flights on the outside of the field QAPP.DOC 4-1 May 2000