Current through Register Vol. 24-06, March 15, 2024
(1)
Groundwater monitoring
General provisions.
(a)
Applicability. This section applies to limited purpose
landfills subject to WAC
173-350-400
and surface impoundments that do not have a leak detection layer subject to WAC
173-350-330.
Subsections (1), (3), (4) and (5) of this section apply to all such facilities,
and subsection (2) of this section applies to WAC
173-350-400
Limited purpose landfills, only.
(b) Jurisdictional health departments are
responsible for regulation of groundwater monitoring at landfills and other
solid waste handling facilities they permit, except in instances where
responsibility is shared with the department.
(c) All reports, plans, procedures, and
design specifications required by this section must be prepared by a licensed
professional in accordance with the requirements of chapter 18.220 RCW,
Geologists.
(2)
Groundwater monitoring - Site characterization for landfill sites.
A site proposed for limited purpose landfill activities subject to WAC
173-350-400
must be characterized for its geologic and hydrogeologic properties and
suitability for constructing, operating, and monitoring the facility in
accordance with all applicable requirements of this chapter. The site
characterization report must be submitted with the permit application and must
include at a minimum the following:
(a) A
summary of local and regional geology and hydrology, including:
(i) Faults;
(ii) Joints and fractures;
(iii) Unstable slopes and subsidence areas
on-site;
(iv) Areas of groundwater
recharge and discharge;
(v)
Stratigraphy; and
(vi) Erosional
and depositional environments .
(b) A site-specific borehole program that
includes a description of lithology, soil/bedrock types and properties,
preferential groundwater flow paths or zones of higher hydraulic conductivity,
the presence of confining unit(s) and geologic features such as fault zones,
cross-cutting structures, the target hydrostratigraphic unit(s) to be
monitored, and other relevant information. All procedures conducted must follow
current applicable ASTM procedures. A list of procedures that were followed
must be identified in subsequent report(s). Requirements of the borehole
program include:
(i) Each boring will be of
sufficient depth below the proposed grade of the bottom liner to identify soil,
bedrock, and hydrostratigraphic unit(s);
(ii) Boring samples must be collected from
five-foot intervals at a minimum and at changes in lithology. Representative
samples must be described using the unified soil classification system; and
tested for the following, if appropriate:
(A)
Particle size distribution by sieve and hydrometer analyses;
(B) Atterburg limits;
(C) Moisture content sufficient to
characterize the unit;
(D) Shear
strength and consolidation testing on soft or potentially weak layers, for use
in stability and settlement analyses; and
(E) Hydraulic conductivity by an in situ
field method or laboratory method.
(iii) All boring logs must be submitted with
the following information:
(A) Soil and rock
descriptions and classifications;
(B) Method of sampling;
(C) Sample depth, interval and
recovery;
(D) Date of
boring;
(E) Water level
measurements;
(F) Standard
penetration number;
(G) Boring
location; and
(H) Soil test data
(in report text or on log).
(iv) All borings not converted to monitoring
wells or piezometers shall be carefully backfilled, plugged, and recorded in
accordance with WAC
173-160-420;
(v) During the borehole drilling program, any
on-site drilling and lithologic unit identification must be performed under the
direction of a licensed professional in accordance with the requirements of
chapter 18.220 RCW, Geologists, who is trained to sample and identify soils and
bedrock lithology;
(vi) An on-site
horizontal and vertical reference datum must be established during the site
characterization. The standards for land boundary surveys and geodetic control
surveys and guidelines for the preparation of land descriptions must be used to
establish borehole and monitoring well coordinates and casing elevations from
the reference datum; and
(vii)
Other methods, including geophysical techniques, may be used to supplement the
borehole program to ensure that a sufficient hydrogeologic site
characterization is accomplished.
(c) A site-specific flow path analysis that
includes:
(i) The depths to groundwater and
hydrostratigraphic unit(s) including transmissive and confining units;
and
(ii) Potentiometric surface
elevations and contour maps, direction and rate of horizontal and vertical
groundwater flow.
(d)
Identification of the quantity, location, and construction (where available) of
private and public wells within a two thousand-foot radius, measured from the
edge of the solid waste handling unit;
(e) Tabulation of all water rights for
groundwater and surface water within a two thousand-foot radius, measured from
site boundaries;
(f) Identification
and description of all surface waters within a one-mile radius, measured from
the edge of the solid waste handling unit;
(g) A summary of all previously collected
site ground-water and surface water analytical data, and for expanded
facilities, identification of impacts of the existing facility upon ground and
surface waters from landfill leachate discharges to date;
(h) Calculation of a site water
balance;
(i) Conceptual design of
groundwater and surface water monitoring systems, and where applicable surface
water and vadose zone monitoring systems, including proposed construction and
installation methods for these systems;
(j) Description of land use in the area,
including nearby residences;
(k) A
topographic map of the site and drainage patterns, including an outline of the
solid waste handling unit, property boundary, the proposed location of
groundwater monitoring wells, and township and range designations;
and
(l) Geologic cross
sections.
(3)
Groundwater monitoring - System design.
(a) The groundwater monitoring system design
and report must be submitted with the permit application and must meet the
following criteria:
(i) A sufficient number of
monitoring wells must be installed at appropriate locations and depths to yield
representative groundwater samples from those hydrostrati-graphic units which
have been identified during site characterization as the earliest potential
contaminant flow-paths;
(ii)
Represent the quality of groundwater at the point of compliance, and include at
a minimum:
(A) A groundwater flow path
analysis which supports why the chosen hydrostratigraphic unit is capable of
providing an early warning detection of any groundwater
contami-nation;
(B) Documentation
and calculations of all of the following information:
(I) Hydrostratigraphic unit thickness
including confining units and transmissive units;
(II) Vertical and horizontal groundwater flow
directions including seasonal, man-made, or other short-term fluctuations in
groundwater flow;
(III)
Stratigraphy and lithology;
(IV)
Hydraulic conductivity; and
(V)
Porosity and effective porosity.
(b) Upgradient monitoring wells (background
wells) must meet the following performance criteria:
(i) Must be installed in groundwater that has
not been affected by leakage from a solid waste handling unit; or
(ii) If hydrogeologic conditions do not allow
for the determination of an upgradient monitoring well, then sampling at other
monitoring wells which provide representative background groundwater quality
may be allowed.
(c)
Downgradient monitoring wells (compliance wells) must meet the following
performance criteria:
(i) Represent the
quality of groundwater at the point of compliance;
(ii) Be installed as close as practical to
the point of compliance; and
(iii)
When physical obstacles preclude installation of groundwater monitoring wells
at the point of compliance, the downgradient monitoring system may be installed
at the closest practical distance hydraulically downgradient from the point of
compliance that ensures detection of groundwater contamination in the chosen
hydrostratigraphic unit.
(d) All monitoring wells must be constructed
in accordance with chapter 173-160 WAC, Minimum standards for construction and
maintenance of wells, and chapter 173-162 WAC, Regulation and licensing of well
contractors and operators.
(e) The
owner or operator must notify the jurisdictional health department and the
department of any proposed changes to the design, installation, development,
and decommission of any monitoring wells, piezometers, and other measurement,
sampling, and analytical devices. Proposed changes must not be implemented
prior to the jurisdictional health department's written approval. Upon
completing changes, all documentation, including date of change, new monitoring
well location maps, boring logs, and monitoring well diagrams, must be
submitted to the jurisdictional health department and must be placed in the
operating record.
(f) All
monitoring wells, piezometers, and other measurement, sampling, and analytical
devices must be operated and maintained so that they perform to design
specifications throughout the life of the monitoring program.
(4)
Groundwater monitoring -
Sampling and analysis plan.
(a) The
groundwater monitoring program must include consistent sampling and analysis
procedures that are designed to provide monitoring results that are
representative of groundwater quality within site monitoring wells. In addition
to monitoring wells, facilities with hydraulic gradient control and/or leak
detection systems will provide representative groundwater samples from those
systems. The owner or operator must submit a compliance sampling and analysis
plan as part of the permit application. The plan must include procedures and
techniques for:
(i) Sample collection and
handling;
(ii) Sample preservation
and shipment;
(iii) Analytical
constituents and procedures;
(iv)
Chain-of-custody control;
(v)
Quality assurance and quality control;
(vi) Decontamination of drilling and sampling
equipment;
(vii) Procedures to
ensure employee health and safety during well installation and monitoring;
(viii) Well operation and
maintenance procedures; and
(ix)
Statistical analysis methods.
(b) Facilities collecting leachate must
include leachate sampling and analysis as part of the plan in (a) of this
subsection.
(c) The groundwater
monitoring program must include sampling and analytical methods that are
appropriate for groundwater samples. The sampling and analytical methods must
provide sufficient sensitivity, precision, selectivity and limited bias so that
changes in groundwater quality can be detected and quantified. All samples must
be sent to an accredited laboratory for analyses in accordance with chapter
173-50 WAC, Accreditation of environmental laboratories.
(d) Groundwater elevations must be measured
in each monitoring well immediately prior to sampling purging, each time
groundwater is sampled. The owner or operator must determine the rate and
direction of groundwater flow each time groundwater is sampled. All groundwater
elevations must be determined by a method that ensures measurement to the one
hundredth of a foot relative to the top of the well casing.
(e) Groundwater elevations in monitored wells
must be measured within a period of time short enough to avoid any groundwater
fluctuations which could preclude the accurate determination of groundwater
flow rate and direction.
(f) The
owner or operator must establish background groundwater quality in all
upgradient monitoring wells, and all future downgradient monitoring wells at
landfill sites where waste has not yet been deposited. Background groundwater
quality must be based upon a minimum of eight independent samples. Samples must
be collected for each monitoring well and must be analyzed for parameters
required in the permit for the first year of groundwater monitoring. Each
independent sampling event must be no later than one month after the previous
sampling event.
(g) Groundwater
quality must be determined at each monitoring well at least quarterly during
the active life of the landfill or impoundment, and the post-closure period of
the landfill. More frequent monitoring may be required to protect down-gradient
water supply wells. Groundwater monitoring must begin after background
groundwater quality has been established. Laboratory analysis methods must have
sufficiently low detection limits, when practical, to determine whether
constituent concentrations exceed chapter 173-200 WAC, Water quality standards
for groundwaters of the state of Washington, criteria. The owner or operator
may propose an alternate groundwater monitoring frequency; however, groundwater
monitoring frequency must be no less than semiannually. The owner or operator
must apply for a permit modification or must apply during the renewal process
for changes in groundwater monitoring frequency making a demonstration based on
the following information:
(i) A
characterization of the hydrostratigraphic unit(s) including the unsaturated
zone, transmissive and confining units and include the following:
(A) Hydraulic conductivity; and
(B) Groundwater flow rates.
(ii) Minimum distance between
upgradient edge of the solid waste landfill and/or the impoundment and
downgradient monitoring wells (minimum distance of travel); and
(iii) Contaminant fate and transport
characteristics.
(h) All
facilities must test for the following parameters:
(i) Field parameters:
(A) pH;
(B) Specific conductance;
(C) Temperature; and
(D) Static water level.
(ii) Geochemical indicator parameters:
(A) Alkalinity (as Ca
CO3);
(B)
Bicarbonate (HCO3);
(C) Dissolved calcium (Ca);
(D) Chloride (Cl);
(E) Total and dissolved iron (Fe);
(F) Total and dissolved magnesium
(Mg);
(G) Total and dissolved
manganese (Mn);
(H) Nitrate
(NO3);
(I)
Dissolved potassium;
(J) Dissolved
sodium (Na); and
(K) Sulfate
(SO4).
(iii) Leachate indicators:
(A) Ammonia
(NH3-N);
(B)
Total organic carbon (TOC); and
(C)
Total dissolved solids (TDS).
(i) If other pertinent constituents are
identified based upon the site specific waste profile and/or leachate
characteristics for lined facilities, if tested, the owner or operator must
propose those additional constituents to include in the monitoring program. The
jurisdictional health department will specify the additional constituents in
the solid waste permit.
(j) Testing
must be performed in accordance with "Test Methods for Evaluating Solid
Waste, Physical/Chemical Methods," U.S. EPA Publication SW-846, or
other testing methods approved by the jurisdictional health
department.
(k) Maximum contaminant
levels (MCL) for groundwater are those specified in chapter 173-200 WAC, Water
quality standards for groundwaters of the state of Washington.
(5)
Groundwater monitoring -
Data analysis, notification and reporting.
(a) The results of monitoring well sample
analyses as required by subsection (4)(h) and (i) of this section must be
evaluated using an appropriate statistical proce-dure(s), as approved by the
jurisdictional health department . Statistical procedure(s) used must be
proposed in the sampling and analysis plan, and must be capable of determining
whether a significant increase over background has occurred. Selection of
parameters undergoing statistical analysis, as specified in the solid waste
permit, must be based on site-specific leachate analyses, synthetic
precipitation leaching procedure (SPLP) results, or toxicity characteristic
leaching procedure (TCLP) results, if available, and typically at least include
pH, specific conductance, chloride, iron, manganese, nitrate, sul-fate,
ammonia, and total dissolved solids.
(b) If statistical analyses determine a
significant increase over background:
(i) The
owner or operator must:
(A) Notify the
jurisdictional health department and the department of this finding within
thirty days of receipt of the sampling data. The notification must indicate
what parameters or constituents have shown statistically significant
increases;
(B) Within thirty days,
resample parameter(s) showing statistically significant increase(s) in the
monitoring well(s) where the statistically significant increase has occurred;
and
(C) Establish a groundwater
protection standard based on the groundwater quality criteria of chapter
173-200 WAC, Water quality standards for groundwaters of the state of
Washington. If the background concentration level established in the facility's
monitoring record for a constituent is greater than the numeric criterion for
the constituent in chapter 173-200 WAC, Water quality standards for
groundwaters of the state of Washington, the owner or operator must use the
background concentration as the protection standard.
(ii) The owner or operator may demonstrate
that a source other than a landfill unit or surface impoundment caused the
contamination, or the statistically significant increase resulted from error in
sampling, analyses, statistical evaluation, or natural variation in groundwater
quality. If a demonstration cannot be made and the concentrations or levels of
the constituents exceed the criteria established by chapter 173-200 WAC, Water
quality standards for groundwaters of the state of Washington, the owner or
operator must:
(A) Characterize the chemical
composition of the release and the contaminant fate and transport
characteristics by installing additional monitoring wells;
(B) Assess and, if necessary, implement
appropriate intermediate measures to remedy the release. The measures must be
approved by the jurisdictional health department and the department;
and
(C) Evaluate, select, and
implement remedial actions in accordance with chapter 173-340 WAC, Model Toxics
Control Act- Cleanup . The roles of the jurisdictional health department and
the department in remedial action are further defined by WAC
173-350-900.
(c) The owner or
operator must submit an annual report to the jurisdictional health department
and the department by April 1st of each year. However, more frequent reporting
may be required. Reports may be submitted to the department in either digital
format or hard copy. The annual report must summarize and interpret the
following information:
(i) All groundwater
monitoring data, including laboratory and field data for the sampling
periods;
(ii) Statistical results
and/or any statistical trends including any findings of any statistical
increases for the year and time/concentration series plots;
(iii) A summary of concentrations above the
maximum contaminant levels of chapter 173-200 WAC, Water quality standards for
groundwaters of the state of Washington;
(iv) Static water level readings for each
monitoring well for each sampling event;
(v) Potentiometric surface elevation maps
depicting flow direction for each sampling event;
(vi) Groundwater flow velocity calculations
for each sampling event, and a discussion of any trends or changes during the
year;
(vii) Geochemical evaluation
including cation-anion balancing and trilinear and/or stiff diagraming for each
sampling event noting any changes or trends in water chemistry for each well
during the year; and
(viii)
Leachate, hydraulic gradient control and/or leak detection system results, if
applicable, for each sampling event.
(d) All groundwater monitoring data must be
submitted consistent with procedures specified by the department. Unless
otherwise specified by the department, all groundwater monitoring data for the
previous year must be submitted by April 1st of each year in an electronic form
capable of being transferred into the department's data management
system.
Statutory Authority:
Chapter
70.95 RCW. 03-03-043
(Order 99-24), § 173-350-500, filed 1/10/03, effective
2/10/03.