TM 5-814-7
CHAPTER 8
GROUND-WATER MONITORING
constituent specified in the permit. If so, the EPA
8-1. Introduction
Regional Administrator (RA) establishes a ground-water
a. Subpart F of 40 CFR 264 establishes
protection standard for the facility.
standards for groundwater protection and monitoring that
c. Ground-water protection standard.
The
apply to owners or operators who treat, store or dispose
groundwater protection standard indicates when
of hazardous waste in surface impoundments, waste
corrective action is necessary to control contamination
piles, land treatment units, or landfills.
from a regulated hazardous waste unit. The standard
b. Under Interim Status regulations in 40 CFR
has four main parts: (1) the hazardous constituents to be
265:F, existing surface impoundments, landfills or land
monitored (section 264.93), (2) the concentration limits
treatment facilities are also required to implement
for each hazardous constituent that trigger corrective
ground-water monitoring programs to determine the
action (section 264.94), (3) the point of compliance
facilities' impact on ground water.
(section 264.95), and (4) the compliance period (section
c. If an existing facility is upgraded, the facility
264.96).
owner or operator must continue to comply with the
d. Compliance monitoring.
Compliance
interim status regulations specified in 40 CFR 265:F until
monitoring (section 264.99) is implemented when
final administrative action on the facility's permit
detection monitoring reveals a confirmed, statistically
application.
Initial background water quality data
significant increase in any parameter or constituent
collected during this period is used for the detection
specified.
and/or compliance monitoring programs regulated by 40
(1) Compliance
monitoring
requires
CFR 264:F once a permit is granted to the facility. The
quarterly sampling at the compliance point for
designer should be aware, however, that the monitoring
hazardous constituents specified in the ground-water
system installed at existing facilities in compliance with
protection standard. Analysis for all appendix VIm of 40
the interim status regulations may not meet the more
CFR 261 hazardous constituents must also be done
stringent standards for permitted facilities and may
annually.
require modifications or additions.
(2) Data collected from these tests are
d. Many variables exist within a given
analyzed to determine if a statistically significant increase
hydrogeologic environment that affect ground-water
in hazardous constituent concentration has occurred. If
occurrence. To yield usable information, as well as to
so, a corrective action program is implemented at the
ensure their effectiveness, monitoring programs must
RA's direction.
therefore be designed based on a thorough knowledge
e. Corrective action program. A corrective
of site hydrogeology (EPA SW-963, SW-611).
action program (section 264.100) is undertaken to
ensure that hazardous waste units are brought into
8-2. Monitoring requirements
compliance with the ground-water protection standard.
This goal must be achieved by either removing the
a. Background
ground-water
quality.
hazardous constituents or treating them in place.
Section 264.97 requires that ground-water quality data
Corrective action may be terminated only after ground-
be collected at all hazardous waste units to establish a
water monitoring data demonstrate that the standard has
background value for any hazardous constituents or
not been exceeded for three consecutive years.
monitoring parameters specified in the facility permit.
Sampling frequency and techniques are detailed in the
8-3. Monitoring program
regulations.
b. Detection monitoring.
A detection
a. Determining the hydrogeologic environment
monitoring program (section 264.98) is required at all
of a waste disposal unit is an essential first step in
hazardous waste units to provide an early indication of
designing and planning a monitoring program. The
leakage into the uppermost aquifer.
hydrogeologic investigation should include identification
(1) Detection monitoring, conducted at
of the uppermost aquifer, determination of the hydraulic
least semiannually, determines ground-water quality at
conductivity of underlying formations, and determination
the point of compliance. The parameters or constituents
of seasonal and other fluctuations in ground-water
requiring monitoring are specified in the facility permit.
surface elevation, which will yield information on
(2)
The information collected is
hydraulic gradients and flow direction.
Subsurface
analyzed to determine whether there has been a
cross-sections, prepared from boring logs, geophysical
statistically significant increase over background values
surveys and existing site information, may be used in
for
any
parameter
or
conjunction with a base map to characterize the
hydrogeologic environment of the site. Methods of
determin-
8-1
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