FRTR Field Sampling and Analysis Technologies Reference Guide

3 ACCESS TOOLS

3.1 DRILLING METHODS - UNCONSOLIDATED FORMATIONS

3.1.4 Solid Flight and Bucket Augers

Use:

Solid flight augers are commonly used for site characterization in unconsolidated material. They are less common during monitoring well installation where penetration into the saturated zone is generally necessary. Bucket type augers are better for direct sample recovery since they provide a large volume of samples in a short time. This method is generally more appropriate for the construction of wells in unconsolidated formations that will form stable borehole walls such as clays.

Description:

Auger sections with a solid stem and flighting (corkscrew-like blades) are connected in a continuous string to the lowest section with a cutting head that is approximately 2 inches larger in diameter than the flighting. Cuttings are rotated upward to the surface by moving along the flighting as the cutting head advances into the ground. Bucket augers (8 inches in diameter and typically 2 feet long) have a cutting edge on the bottom that is slowly rotated by a square telescoping drill stem. When the bucket fills with cuttings, it is brought to the surface to be emptied.

Augers can be hand held or power driven. Solid flight and bucket augers are generally operated in conjunction with a drill rig. Traditional hand-held augers are identified in Section 4.1.2

Analytes:

1. Non-Halogenated VOCs	5. PAHs	9. Inorganics
2. Non-Halogenated SVOCs	6. Pesticides/Herbicides	10. Explosives
3. Halogenated VOCs	7. Metals	11. TPHs
4. Halogenated SVOCs	8. Radionuclides

Media:

Soil:	Ground Water:	Surface Water:	Gas/Air:
MINIMUM	MODERATE	Not Applicable	MAXIMUM

Soil samples using solid flight augers are unreliable unless split-spoon or thin-wall samples are taken and drilling speed is slowed. Soil samples taken with a bucket auger are disturbed, but representative unless caving of the borehole has occurred.

In stable soils, rotation can be stopped at the desired depth, the auger removed from the borehole, and samples taken from the bottom flight. Recovery of samples from the saturated zone is difficult. The only way to collect undisturbed samples is to remove the auger string, attach a split-spoon or thin-wall sampler to the end of the drill rod, and put the entire string back into the borehole.

Maximum Depth:	Solid flight augers: depth generally restricted to <150 feet. Bucket augers: restricted to depths of 50 feet or less.
Production Rate:	Sample is available after a short amount of time. A depth of 15 to 20 feet should take 25 to 45 minutes.
Investigation Derived Waste Volume:	Large volume of waste.
Technology Status:	Commercially available and routinely used field technology.
Certification/Verification:	Technology has not participated in CalEPA certification and/or CSCT verification program.
Relative Cost per Sample:	Mid-range expense. Purchase price for a flighted auger kit ranges from $2,750 to $3,000.

Limitations:

Solid flight augers:

Generally unsuitable for monitoring well installation in the saturated zone because of borehole caving upon auger removal. Depth to water table might be difficult to determine accurately in deep borings.
Drilling through contaminated soil could result in downward transport of contaminants.
Soil samples returned by auger flight are "disturbed" making it difficult to determine the precise depth of the sample. Auger samples returned after drilling below the water table are not reliable because of the upward vertical mixing of borehole fluid and augered cuttings can occur.
Borehole can be smeared by previously drilled clay.
Borings limited to drilling to relatively shallow depths in normal soils or soft rock.
Difficult drilling in saturated soils and soils containing very coarse gravel, cobbles, or boulders.
Difficult drilling in extremely dry, fine materials.
Bucket augers:
Large diameter holes create a large annular space when small-diameter casing is used, necessitating a large volume of grout and backfilling.
In installations below the water table, water must be added continuously to prevent caving.

ASTM Standards:

D 1452 - 80 (1995)

Soil Investigation and Sampling by Auger Borings .

Sample Access/Collection Matrix

Sample Analysis Matrix

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