United States Office of Research and EPA/600-R-98/092
Environmental Protection Development August 1998
Agency Washington DC 20460
«€PA Innovative Technology
Verification Report
Soil Sampling Technology
Geoprobe Systems, Inc. Large
Bore Soil Sampler
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
Environmental Technology Verification Program
Verification Statement
TECHNOLOGY TYPE: Sediment Sampler
APPLICATION: Subsurface Soil Sampling
Technology Name: Large-Bore Soil Sampler
Company: Geoprobe® Systems, Inc.
Address: 601 North Broadway
Salina, Kansas 67401
Phone: (913) 825-1842
ETV Program Description
The U.S. Environmental Protection Agency (EPA created the Environmental Technology Verification (ETV)
Program to facilitate the deployment of innovative technologies through performance verification and information
dissemination. The goal of the ETV Program is to further environmental protection by substantially accelerating the
acceptance and use of improved and cost-effective technologies. The ETV Program is intended to assist and inform
those involved in the design distribution, permitting, and purchase of environmental technologies. This document
summarizes the results of a demonstration of the Geoprobe® Systems, Inc., Large-Bore Soil Sampler.
Program Operation
Under the ETV Program and with the full participation of the technology developer, the EPA evaluates the
performance of innovative technologies by developing demonstration plans, conducting field tests, collecting and
analyzing demonstration data, and preparing reports. The technologies are evaluated under rigorous quality assurance
(QA) protocols to ensure that data of known and adequate quality are generated and that the demonstration results are
defensible. The EPA's National Exposure Research Laboratory, which demonstrates field characterization and
monitoring technologies, selected Tetra Tech EM Inc. as the verification organization to assist in field testing various
soil and soil gas sampling technologies. This demonstration was conducted under the EPA's Superfund Innovative
Technology Evaluation Program.
Demonstration Description
In May and June 1997, The EPA conducted a field test of the Geoprobe® Large-Bore Soil Sampler along with three
other soil and two gas sampling technologies. This Verification statement focuses on the Geoprobe® Large-Bore Soil
Sampler ; similar statements have been prepared for each of the other technologies. The performance of the Large-
Bore Soil Sampler Sampler was compared to a reference subsurface soil sampling method (hollow-stem auger
drilling and split-spoon sampling) in terms of the following parameters: (1) sample recovery, (2) volatile organic
compound (VOC) concentrations in recovered samples, (3) sample integrity, (4) reliability and throughput, and (5)
cost. Data quality indicators for precision, accuracy, representativeness, completeness, and comparability were also
assessed against project-specific QA objectives to ensure the usefulness of the data.
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The ESP was demonstrated at two Sites: The Small Business Administration (SBA) site in Albert City, Iowa, and the
Chemical Sales Company (CSC) site in Denver, Colorado. These sites were chosen because of the wide range of
VOC concentrations detected at the sites and because each has a distinct soil type. The VOCs detected at the sites
include cis-l,2-dichloroethene (cis-l,2-DCE); 1,1,1-trichloroethane (1,1,1-TCA); trichloroethene (TCE); and
tetrachloroethene (PCE). Soils at the SBA site are composed primarily of clay, and soils at the CSC site are
composed primarily of medium- to fine-grained sand. A complete description of the demonstration, including a data
summary and discussion of results, is available in a report titled Environmental Technology Verification Report: Soil
Sampler, Geoprobe® Systems, Inc., Large-Bore Soil Sampler, EPA 600/R-98/092.
TECHNOLOGY DESCRIPTION
The Large-Bore Soil Sampler is a single tube-type, solid-barrel, closed-piston device advanced by using direct-push
techniques to collect discrete interval samples of unconsolidated materials at depth. The sampler is 24 inches long
with a 1.5-inch outside diameter. It is capable of recovering a discrete sample in the form of a 22-inch by 1-1/16-
inch core. The sampler can be used with 24-inch long and 1-1/8-inch diameter disposable liners. In some cases,
liners may facilitate retrieval of the sample and maybe used for sample storage when applicable.
VERIFICATION OF PERFORMANCE
The demonstration data indicate the following performance characteristics for the Large-Bore Soil Sampler:
Sample Recovery: For purposes of this demonstration, sample recovery was defined as the ratio of the length of
recovered sample to the length of sampler advancement. Sample recoveries from 42 samples collected at the SBA
site ranged from 65 to 100 percent, with an average sample recovery of 98 percent. Sample recoveries from 42
samples collected at the CSC site ranged from 42 to 94 percent, with an average sample recovery of 78 percent.
Using the reference method, sample recoveries from 42 samples collected at the SBA site ranged from 40 to 100
percent, with an average recovery of 88 percent. Sample recoveries from the 41 samples collected at the CSC site
ranged from 53 to 100 percent, with an average recovery of 87 percent. A comparison of average recovery data
from the Large-Bore Soil Sampler and the reference sampler indicates that the Large-Bore Soil Sampler achieved
higher sample recoveries in the clay soil at the SBA site and lower recoveries in the sandy soil at the CSC site
relative to the sample recoveries achieved by the reference sampling method.
Volatile Organic Compound Concentrations: Soil samples collected using the Large-Bore Soil Sampler and the
reference sampling method at six sampling depths within nine grids (five at the SBA site and four at the CSC site)
were analyzed for VOCs. For 20 of the 23 Large-Bore Soil Sampler and reference sampling method pairs (12 at
the SBA site and 11 at the CSC site), a statistical analysis using the Mann-Whitney test indicated no significant
statistical difference at the 95 percent confidence level between the VOC concentrations detected in samples
collected with the Large-Bore Soil Sampler and those collected with the reference sampling method. A statistically
significant difference was identified for three sample pairs: one pair at the SBA site and two pairs at the CSC site.
Analysis of the SBA site data, using the sign test, indicated no statistical difference between the data obtained by the
Large- Bore Soil Sampler and by the reference sampling method. However, at the CSC site, the sign test indicated
that the VOC data (cis-l,2-DCE, 1,1,1-TCA, TCE, and PCE) obtained by the Large-Bore Soil Sampler are
statistically significantly different than the data obtained by the reference sampling method, suggesting that the
reference method tends to yield higher concentrations in sampling coarse-grain soils than does the Large-Bore Soil
Sampler.
Sample Integrity: Six integrity samples were collected with the Large-Bore Soil Sampler at each site to determine
if potting soil in a lined sampler became contaminated after it was advanced through a zone of high VOC
concentrations. Seven integrity samples were collected with the reference sampling method at the SBA site and five
integrity samples were collected at the CSC site. For the Large-Bore Soil Sampler, VOCs were detected in five of
the 12 integrity samples, all at the SBA site. The range of VOC concentrations detected above the analytical
detection limit in the potting soil at the SBA site were: cis-l,2-DCE (3.42 to 295 micrograms per kilogram [//g/kg])
and TCE (14.4 to 46.3 //g/kg). These results indicate that the integrity of the lined chamber in the Large-Bore Soil
Sampler may not be preserved when the sampler is advanced through highly contaminated soils. Results of sample
integrity tests for the reference sampling method indicate no contamination in the potting soil after advancement
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through a zone of high VOC concentrations. Because potting soil has an organic carbon content many times greater
than typical soils, the integrity tests represent a worst-case scenario for VOC absorbance and may not be
representative of cross-contamination under normal field conditions.
Reliability and Throughput. At the SBA site, the Large-Bore Soil Sampler collected a sample from the desired depth
on the initial attempt 93 percent of the time. Sample collection in the initial push was achieved 100 percent of the
time at the CSC site. The initial push success rate was less than 100 percent primarily because of refusal due to
cobbles. By conducting multiple pushes, the Large-Bore Soil Sampler did collect all of the samples required for this
demonstration, yielding a sampling completeness of 100 percent. For the reference sampling method, the initial
sampling success rates at the SBA and CSC sites were 90 and 95 percent, respectively. Success rates for the
reference sampling method were less than 100 percent due to (1) drilling beyond the target sampling depth, (2)
insufficient sample recovery, or (3) auger refusal. The average sample retrieval time for the Large-Bore Soil
Sampler to set up on a sampling point, collect the specified sample, grout the hole, decontaminate the sampler, and
move to a new sampling location was 27.5 minutes per sample at the SBA site and 15.3 minutes per sample at the
CSC site. For the reference sampling technique, the average sample retrieval times at the SBA and CSC sites were
26 and 8.4 minutes per sample, respectively. During the performance range tests at Grid 5 at the CSC site, the
Large-Bore Soil Sampler successfully collected all seven soil samples within the saturated zone from 40 feet below
ground surface (bgs) at Grid 5; however, the Large-Bore Soil Sampler failed once to collect a sample on the initial
attempt from the target depth of 40 feet in Grid 5. This sample was collected on the subsequent push. The reference
method collected all seven samples from the saturated zone at 40 feet bgs on the initial attempts. One person
collected soil samples using the Large-Bore Soil Sampler at the SBA site (except Grid 1 where a two-person crew
was used), and a two-person sampling crew collected soil samples at the CSC site. A three-person sampling crew
collected soil samples using the reference method at both sites. One additional person was present at the CSC site
to oversee and assist with sample collection using the reference method.
Cost: Based on the demonstration results and information provided by the vendor, the Large-Bore Soil Sampler and
equipment costs ranged from $1,330 to $1,450 per day at both sites. Oversight costs for the Large-Bore Soil
Sampler ranged from $1,480 to $2,510 at the clay soil site and $1,080 to $1,860 at the sandy soil site. For this
demonstration, reference sampling was procured at a lump sum of $13,400 for the clay soil site and $7,700 for the
sandy soil site. Oversight costs for the reference sampling method ranged from $4,230 to $6,510 at the clay soil
site and $1,230 to $2,060 at the sandy soil site. A site-specific cost and performance analysis is recommended
before selecting a subsurface soil sampling method.
A qualitative performance assessment of the Large-Bore Soil Sampler indicated that (1) the reliability of the sampler
was better than the reference sampling method; (2) the sampler is easy to use and requires minimal training to
operate; (3) logistical requirements are similar to those of the reference sampling method; (4) sample handling is
similar to the reference method; (5) the performance range is primarily a function of the advancement platform; and
(6) no drill cuttings are generated when using the Large-Bore Soil Sampler with a push platform.
The demonstration results indicate that the Large-Bore Soil Sampler can provide useful, cost-effective samples for
environmental problem-solving. However, in some cases, VOC data collected using the Large-Bore Soil Sampler
may be statistically different from VOC data collected using the reference sampling method. Also, the integrity of
a lined sample chamber may not be preserved when the sampler is advanced thorough highly contaminated zones
in clay soils. As with any technology selection, the user must determine what is appropriate for the application and
project data quality objectives.
Gary J. Foley, Ph.D.
Director
National Exposure Research Laboratory
Office of Research and Development
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NOTICE: EPA verifications are based on an evaluation of technology performance under specific, predetermined criteria and
appropriate quality assurance procedures. EPA makes no expressed or implied warranties as to the performance of the
technology and does not certify that a technology will always operate as verified. The end user is solely responsible for
complying with any and all applicable federal, state, and local requirements.
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