1. Soil and Rock Sampling

2. Environmental Site Characterization Number of samples taken depends on the size of the site Hollow stem auger normally used for environmental work Usually sample every 5ft in depth or at every change in formation

3. Sample Examination Samples are examined in field for physical characteristics –Grain size, color, degree of sorting, and moisture content –Visually present contamination –Usually screened in field using FID (flame ionization detector) PID (photoionization detector) – for volatile organic compound (VOCs)

4. Sample Examination Cont’d A selected number of samples are sent to the lab –Usually one per soil boring –Shipped in jars to off-site lab for chemical analyses –Waiting period of 6 to 10 weeks

5. Sample Examination Cont’d Drill cuttings –Stored in drums –Potentially contaminated –Approx. 1 drum for every 17ft of drilling in a hole drilled with a 4.25 ID hollow stem auger –Analyzed to determine proper disposal

6. Detection Probability A soil or core sample may only be representative of a limited area surrounding the hole –Fractures, bedding planes, solution cavities, bedrock channels, sand lenses, and permeable zones can be missed be borehole programs

7. Types of Samples

8. Bulk Samples  Shovelful or handful of drill cuttings from borehole  Provides generalized picture of formations cut by drilling  Formations are mixed together in this type of sample  Least accurate of four types

9. Representative Samples  Generally taken in some sort of drive or push tube  Represent a specific depth interval in a borehole  Chemical constituents present but not necessarily undisturbed

10. Undisturbed Samples  Physical and chemical disturbances minimized  All parts of formation sampled without altering presampling relationship  Required for hydraulic conductivity testing

11. Composite Samples  Combination of discrete samples from different intervals in the same borehole, mixed to represent the entire borehole  Combination could be from same formation in different boreholes  Represents similar formation materials across site

12. Types of Soil Samplers

13. Solid Barrel Sampler Consists of steel tube attached to a connector head at top and drive shoe at bottom Consists of steel tube attached to a connector head at top and drive shoe at bottom 12-60in long, 1-6in wide 12-60in long, 1-6in wide Sampler made of steel or stainless steel with brass, stainless steel or plastic liner Sampler made of steel or stainless steel with brass, stainless steel or plastic liner –Liner material determined by specific application

14. Split-Barrel Samplers Tubular section is split longitudinally into two semi-cylindrical halves Tubular section is split longitudinally into two semi-cylindrical halves Made from high strength or stainless steel Made from high strength or stainless steel Driven in 2ft increments Driven in 2ft increments Most commonly used sampler in geo-tech and environmental work Most commonly used sampler in geo-tech and environmental work Samples are often physically disturbed, but are suitable for soil chem testing Samples are often physically disturbed, but are suitable for soil chem testing

15. Thin-Wall Tube Samplers Consists of a connector head and a length of thin-wall steel brass or stainless steel tube Consists of a connector head and a length of thin-wall steel brass or stainless steel tube Usually 30in tube for 24in sample Usually 30in tube for 24in sample Sharpened at cutting end and crimped to 1% of its inside diameter to allow free movement of the sample into the tube Sharpened at cutting end and crimped to 1% of its inside diameter to allow free movement of the sample into the tube Primarily used in cohesive, soft, or clayey formations where a relatively undisturbed sample is required Primarily used in cohesive, soft, or clayey formations where a relatively undisturbed sample is required

16. Continuous Tube Sampler Used exclusively with a hollow-stem auger Used exclusively with a hollow-stem auger 5ft long split-barrel sampling tube, cutting shoe at bottom, head at top 5ft long split-barrel sampling tube, cutting shoe at bottom, head at top The head connects in a way that allows the sampling tube to remain stationary while the auger turns The head connects in a way that allows the sampling tube to remain stationary while the auger turns Works well in clays and other cohesive soils and in granular material above the water table Works well in clays and other cohesive soils and in granular material above the water table Material inflow may occur when the water table is encountered Material inflow may occur when the water table is encountered –This makes it very difficult to recover samples

17. Rotary Samplers Pitcher or Denison sampler, or the Geo- barrel Pitcher or Denison sampler, or the Geo- barrel Requires circulation fluids Requires circulation fluids Useful for Geo-tech work, not environmental Useful for Geo-tech work, not environmental Retrieves disturbed and undisturbed samples Retrieves disturbed and undisturbed samples

18. Piston Samplers Consists of a thin-wall tube, a piston, and mechanisms for regulating movement between the tube and the piston Consists of a thin-wall tube, a piston, and mechanisms for regulating movement between the tube and the piston Specifically for use in soft formations Specifically for use in soft formations Some physical disturbance of samples Some physical disturbance of samples The sampler is flush with the end of the fixed piston, lowered into hole on drill rod The sampler is flush with the end of the fixed piston, lowered into hole on drill rod Hydraulic fluids force the tube into the soil while the fixed piston remains stationary Hydraulic fluids force the tube into the soil while the fixed piston remains stationary Sampler then pulled back by hydraulic fluids Sampler then pulled back by hydraulic fluids

19. Methods of Sampling Environmental samples are generally taken from the bottom of the borehole Environmental samples are generally taken from the bottom of the borehole Bulk samples are generally taken from the cuttings Bulk samples are generally taken from the cuttings

20. Driving Most common method for obtaining split barrel samples Most common method for obtaining split barrel samples Uses 140lb safety hammer Uses 140lb safety hammer Hammer sits at ground level Hammer sits at ground level Back-hammering or hydraulic fluid used to lift the sampler Back-hammering or hydraulic fluid used to lift the sampler –Back-hammering may result in loss of sample

21. Driving Cont’d The number of hammer blows made to drive the sampler is recorded for every 6in The number of hammer blows made to drive the sampler is recorded for every 6in –This provides useful information about the type of material being penetrated –If the sampler reaches 50 blows in 6in interval, refusal is met –Excessive hammering may result in drill rod failure

22. Pushing Uses a hydraulic feed system on a drill rig to press the sampler into the soil Uses a hydraulic feed system on a drill rig to press the sampler into the soil The drill rod string should be connected to the drill so hydraulic retract can be used to withdraw samples from the borehole The drill rod string should be connected to the drill so hydraulic retract can be used to withdraw samples from the borehole Normally used for thin-wall tube samplers Normally used for thin-wall tube samplers Occasionally used for split-barrel or solid- barrel samplers in soft soils Occasionally used for split-barrel or solid- barrel samplers in soft soils

23. Rotation While Pushing Denison or Pitcher samplers or continuous tube samplers Denison or Pitcher samplers or continuous tube samplers Sampling barrel is suspended from a bearing inside the barrel so the sampler remains stationary while the auger drills into the formation Sampling barrel is suspended from a bearing inside the barrel so the sampler remains stationary while the auger drills into the formation Sampler barrel is connected to the drill rods or a wire line system for retrieval from the bottom of the borehole Sampler barrel is connected to the drill rods or a wire line system for retrieval from the bottom of the borehole