Oregon Administrative Rules
Chapter 340 - DEPARTMENT OF ENVIRONMENTAL QUALITY
Division 122 - HAZARDOUS SUBSTANCE REMEDIAL ACTION RULES
Section 340-122-0240 - Investigation for Magnitude and Extent of Contamination
Universal Citation: OR Admin Rules 340-122-0240
Current through Register Vol. 63, No. 3, March 1, 2024
(1) If data collected during the initial site characterization do not identify the full nature, magnitude, and extent of soil and groundwater contamination, the responsible person must conduct an investigation for this purpose.
(a) The areal
and vertical extent of soil contamination must be determined.
(b) The areal extent of groundwater
contamination must be determined, including an estimate of groundwater velocity
and flow direction.
(c)
Representative samples of all affected media must be analyzed for reasonably
likely contaminants of concern based on the nature of the release and
applicable remedial options under OAR
340-122-0217.
(d) Expedited site assessment tools (e.g.,
push-probe samplers) may be used to provide a preliminary measure of the
magnitude and extent of groundwater contamination.
(e) If groundwater contamination appears to
have migrated beyond the immediate vicinity of the tank pit, additional
groundwater investigation must be performed in accordance with section (2) of
this rule unless the responsible person can demonstrate to the Department that
the contamination presents no potential threat to human health or the
environment.
(2) Groundwater investigations required by section (1) of this rule, and groundwater monitoring under corrective action plans required by OAR 340-122-0250 must be carried out as follows:
(a)
Groundwater monitoring systems must include a minimum of one hydraulically
upgradient and two hydraulically downgradient groundwater monitoring wells,
capable of adequately characterizing both site hydrogeology and the vertical
and horizontal magnitude and extent of groundwater contamination. Additional
monitoring wells may be required by the Department if necessary to adequately
characterize the site or to establish compliance monitoring points. All
monitoring wells must be designed, completed and, when appropriate, removed
according to the Water Resources Department's administrative rules, OAR
690-240-0005 through
690-240-0180
(Construction and Maintenance of Monitoring Wells and Other Holes in
Oregon).
(b) When the installation
of monitoring wells is impractical due to specific site conditions, the
responsible person must notify the Department and develop an alternative course
of action which must be approved by the Department.
(c) Groundwater sampling events must meet the
following minimum requirements:
(A)
Initially, samples must be collected at quarterly intervals. After four
consecutive quarters of groundwater monitoring, if site conditions warrant more
or less frequent sampling, an alternative sampling schedule may be
proposed;
(B) Water elevation
measurements must be made in all monitoring wells during each sampling event,
unless the Department has approved measurements from a reduced number of wells
that provide sufficient data for the determination of the groundwater flow
direction;
(C) Formal
chain-of-custody records must be prepared and maintained for each sample;
and
(D) All sampling events for
purposes of identifying contaminants of concern, or for verifying either
preliminary compliance or final compliance, must include adequate quality
assurance and quality control (QA/QC) measures.
(3) The responsible person shall submit the information collected under sections (1) and (2) of this rule to the Department within 45 days of completing field work, or within a longer period of time approved by the Department. Groundwater monitoring reports must be submitted after each monitoring event unless an alternative schedule has been approved by the Department, and must contain the following information:
(a) A site map, drawn to scale, showing the
location of all monitoring wells and the direction of groundwater
flow;
(b) A summary of all
sampling, handling, and chain-of-custody procedures followed, including, as
appropriate, a discussion of any routine maintenance procedures performed
during the quarter and any problems encountered (e.g., failure of a pump,
clogging of a well screen, an unexplained change in the quality of the water,
or any other unusual event) and what actions were taken, or will be taken, in
response to such occurrences;
(c) A
summary of the analytical data, including QA/QC results for the sampling
event;
(d) Water elevation
measurements from each monitoring well, unless the Department approves
elevation measurements from a reduced number of wells; and
(e) A written evaluation of data, describing
trends or other pertinent information derived from the sampling event, and
specifying the method or methods of statistical analysis used to describe the
significance of these trends.
Stat. Auth.: ORS 465.400 & ORS 466.746
Stats. Implemented: ORS 465.200 - ORS 465.455 & ORS 466.706 - ORS 466.835
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