Use of Push-Driven Technology

              Use of Push-Driven Technology
What is push-driven technology?
Also known as “direct-drive,” drive-point” or
“direct-push,” push-driven technology refers
to tools used to investigate sites by driving,
pushing, and/or vi brating small-diameter
hollow steel rods into the ground. Sampling
tools can be attached to the end of the steel
rods to collect soil, soil-gas and groundwater
samples.
For purposes of this fact sheet, push-driven
technology also includes push-driven
equipment that is capable of using an auger
tool (similar to that used for a conventional
monitoring well) to install pre-pack
monitoring wells.
What are some of the advantages of
push-driven technology?
Push-driven technology is a useful and cost-effective
technology, which yields accurate
and representative soil and groundwater
samples when used properly. This
technology allows the collection of more
samples in a shorter period of time, easier
mobilization, and the ability to sample in
areas not accessible to a drill rig.
Is push-driven technology acceptable for
sampling?
Yes. Push-driven equipment is acceptable
for sampling soil and groundwater if the
inner diameter of the sampling device is 1.5
inches or greater. However, soil samples
taken solely for analysis of contaminant
(chemical) concentration can be collected
with sampling devices less than 1.5 inches
in diameter.
Specific acceptable uses for the collection of
soil and groundwater samples are described
below.
What are acceptable uses of push-driven
technology for soil?
1. To determine the horizontal and vertical
extent of soil contamination.
2. To determine the physical soil properties
of the soil; for example, laboratory
hydraulic conductivity, soil bulk density,
organic carbon content, etc.
3. To investigate contaminant migration
along natural and man-made pathways.
4. To characterize the unconsolidated
deposits at the site; for example, the
classification of unconsolidated geologic
material and associated thickness or soil
conductivity logging.
5. To investigate soil-gas.
What are acceptable uses of push-driven
technology for groundwater?
1. To determine the rate and extent of
groundwater contamination when the
groundwater is collected through a
screen point sampler or a pre-pack well.
Pre-pack wells are acceptable for
groundwater monitoring for up to one
year. If a pre-pack well is to be used for
greater than one year, a demonstration
as to the integrity of the well (e.g., signs
of frost heave, cracked surface seals,
siltation, missing or broken locking
mechanisms, cracked casing or
standing water around the base of the
well) should be made. Acceptability of a
pre-pack well for greater than one year
is made on a case-by-case basis.
In order to collect a representative
groundwater sample, proper care must
be taken to allow the groundwater to be
clear of sediment, as necessary, before
Illinois Bureau of Land April 2001
Environmental 1021 North Grand Avenue East
Protection Agency Springfield, I L 62794-9276
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beginning sample collection so as not to
disturb the sample (e.g., agitation of
samples for VOC analysis) during
sample collection.
2. To collect static water levels for
determining groundwater flow direction
when static water levels are measured
in pre-pack wells installed with the auger
tool or conventional wells.
Pre-pack wells or piezometers may be
installed using a push method if
adequate site characterization has
already been performed, i.e., the site
has been characterized and the depth to
which the pre-pack wells or piezometers
should be installed is known. Because
of the smaller diameter, special care
should be taken when measuring the
static groundwater level in pre-pack
wells so that groundwater is not
displaced, thus giving an inaccurate
groundwater elevation.
3. To perform an in-situ hydraulic
conductivity test using a pre-pack well
installed with the auger tool or a
conventional well.
What happens if a groundwater sample
cannot be collected?
If you are not able to collect a groundwater
sample, you should not automatically
assume that groundwater does not exist to
that depth. Push-driven sampling
equipment can cause a deformation of the
borehole (i.e., upper unit smearing over a
lower unit) that may interfere with the ability
to collect a groundwater sample. The
deformation (smearing) of the borehole may
cause the groundwater to recharge very
slowly or not at all.
Therefore, in such cases, site-specific
conditions and other available data are to be
evaluated before it is concluded that no
groundwater sample is available to that
depth. This may include, but is not limited
to, inspection of the core to determine any
changes in lithology, lack of recovery,
wet/moist soil and depth of groundwater in
the area through previously installed wells
on-site or off-site. If review of this data
indicates that it is reasonable to expect
groundwater to be present to this depth,
installation of a pre-pack well using an auger
tool or installation of a conventional well may
be warranted. The use of the auger tool
may reduce the smearing effect.
Whether using an auger or push method to
install a groundwater monitoring well
(conventional or pre-pack), there will likely
be some deformation of the borehole wall
(smearing). This forms a skin or film against
the geologic material, potentially inhibiting
groundwater recharge and the ability to
obtain a groundwater sample. Proper
development of the well is essential in
breaking down the skin or film formed during
well installation. Proper development,
including surging, may increase recharge
rates.
What are unacceptable uses of push -
driven technology?
The site classification boring as required for
Method One and Method Two in the Leaking
Underground Storage Tank Program (35
Illinois Administrative Code, Section
732.307) cannot be performed using push-driven
technology. A larger diameter boring
(as with a conventional well and drill rig) is
needed to compare the different
stratigraphic units to the publication Illinois
Geological Survey Circular No. 532 entitled
“Potential for Contamination of Shallow
Aquifers in Illinois” (1984), by Berg, Richard
C., et al.
Will this fact sheet be updated?
Yes. This is an emerging technology and,
as it evolves, the application of this
technology will likely change. Applications
of push-driven technology not addressed in
this procedure may be accepted on a case-by-
case basis.
The Push-Driven Technology fact
sheet is for general information only
and is not intended to replace, interpret
or modify laws, rules and regulations.