Washington Administrative Code
Title 173 - Ecology, Department of (See also Titles 197, 317, 372, and 508)
Chapter 173-304 - Minimum functional standards for solid waste handling
Section 173-304-460 - Landfilling standards
Universal Citation: WA Admin Code 173-304-460
Current through Register Vol. 24-06, March 15, 2024
(1) Applicability. These standards apply to facilities that dispose of solid waste in landfills except for:
(a) Inert wastes and
demolition wastes landfills, that must meet WAC
173-304-461 standards;
and
(b) Woodwaste landfills that
must meet WAC
173-304-462 standards.
(2) Minimum functional standards for performance.
(a) Groundwater. An owner or
operator of a landfill shall not contaminate the groundwater underlying the
landfill, beyond the point of compliance. Contamination and point of compliance
are defined in WAC
173-304-100.
(b) Air quality and toxic air emissions.
(i) An owner or operator of a landfill shall
not allow explosive gases generated by the facility whose concentration
exceeds:
(A) Twenty-five percent of the lower
explosive limit for the gases in facility structures (excluding gas control or
recovery system components);
(B)
The lower explosive limit for the gases at the property boundary or beyond;
and
(C) One hundred parts per
million by volume of hydrocarbons (expressed as methane) in offsite
structures.
(ii) An
owner or operator of a landfill shall not cause a violation of any ambient air
quality standard at the property boundary or emission standard from any
emission of landfill gases, combustion or any other emission associated with a
landfill.
(c) Surface
waters. An owner or operator of a landfill shall not cause a violation of any
receiving water quality standard or violate
chapter
90.48 RCW from discharges
of surface runoff, leachate or any other liquid associated with a
landfill.
(3) Minimum functional standards for design.
(a)
Minimizing liquids. All owners or operators of landfills shall minimize liquids
admitted to active areas of landfills by:
(i)
Covering according to WAC
173-304-460(4)(d);
(ii) Prohibiting the disposal of
noncontainerized liquids or sludges containing free liquids in landfills unless
approved by the jurisdictional health department;
(iii) Designing the landfill to prevent all
the run-on of surface waters and other liquids resulting from a maximum flow of
a twenty-five year storm into the active area of the landfill;
(iv) Designing the landfill to collect the
runoff of surface waters and other liquids resulting from a twenty-four hour,
twenty-five year storm from the active area and the closed portions of a
landfill;
(b) Leachate
systems. All owners or operators of landfills shall:
(i) Install a leachate collection system
sized according to water balance calculations or using other accepted
engineering methods either of which shall be approved by the jurisdictional
health department;
(ii) Install a
leachate collection system so as to prevent no more than two feet of leachate
developing at the topographical low point of the active area; and
(iii) Install a leachate treatment, or a
pretreatment system if necessary in the case of discharge to a municipal waste
water treatment plant, to meet the requirements for permitted discharge under
chapter
90.48 RCW and the Federal
Clean Water Act ( PL 95-217 ).
(c) Liner designs. All owners or operators of
landfills shall use liners of one of the following designs:
(i) Standard design. The liner shall be
constructed of at least a four feet thick layer of recompacted clay or other
material with a permeability of no more than 1 x
10-7 cm/sec and sloped no less than two percent;
or
(ii) Alternative design. The
design shall have two liners:
(A) An upper
liner of at least fifty mils thickness made of synthetic material;
and
(B) A lower liner of at least
two feet thickness of recompacted clay or other material with a permeability of
no more than 1 x 10-6 cm/sec and sloped no less than
two percent; or
(iii)
Equivalent design. The design shall use alternative methods, operating
practices and locational characteristics which will minimize the migration of
solid waste constituents or leachate into the ground or surface water at least
as effectively as the liners of (c)(i) and (ii) of this subsection;
or
(iv) Arid design. This design
will apply to locations having less than twelve inches of precipitation
annually, and, in lieu of (c)(i), (ii), and (iii) of this subsection, shall
consist of vadose zone moisture monitoring, provided that:
(A) Waste material is no less than ten feet
above the seasonal high level of groundwater in the uppermost aquifer;
and
(B) Any evidence of leachate or
waste constituents detected in the vadose zone that violates or could be
expected to violate the performance standard of WAC
173-304-460(2)
shall cause the owner or operator to:
(I) Take
corrective action, and either
(II)
Close the facility according to these rules, or
(III) For all future expansions at that
facility, meet the liner requirement of (c)(i) or (ii) of this
subsection.
(v) Small landfill designs. For a landfill
whose design and permit allow a total capacity at closure of two hundred
thousand cubic yards or less, the need for a liner and leachate collection
system shall be determined on a case-by-case basis by the jurisdictional health
department in consultation with the department.
(d) Flood plains. All owners or operators of
landfills that are located in a one hundred-year flood plain shall:
(i) Comply with local flood plain management
ordinances and chapter 508-60 WAC, Administration of flood control zones;
and
(ii) Design the landfill so
that the landfill entrance or exit roads or practices shall not restrict the
flow of the base flood, reduce the temporary water storage capacity of the
flood plain or result in washout of solid waste, so as to pose a hazard to
human life, wildlife, land or water resources.
(e) Closure. All owners and operators shall
design landfills so that at closure:
(i) At
least two feet of 1 x 10-6 cm/sec or lower
permeability soil or equivalent shall be placed upon the final lifts unless the
landfill is located in an area having mean annual precipitation of less than
twelve inches in which case at least two feet of 1 x
10-5 cm/sec or lower permeability soil or equivalent
shall be placed upon the final lifts. Artificial liners may replace soil covers
provided that a minimum of fifty mils thickness is used;
(ii) The grade of surface slopes shall not be
less than two percent, nor the grade of side slopes more than thirty-three
percent; and
(iii) Final cover of
at least six inches of topsoil be placed over the soil cover and seeded with
grass, other shallow rooted vegetation or other native vegetation.
(f) Gas control.
(i) All owners and operators shall design
landfills, having a permitted capacity of greater than ten thousand cubic yards
per year, so that methane and other gases are continuously collected, and
(A) Purified for sale;
(B) Flared; or
(C) Utilized for its energy value.
(ii) Collection and handling of
landfill gases shall not be required if it can be shown that little or no
landfill gases will be produced or that landfill gases will not support
combustion; in such cases installation of vents shall be required.
(g) Other requirements. All owners
and operators of landfills shall design landfills to:
(i) Be fenced at the property boundary or use
other means to impede entry by the public and animals. A locale gate shall be
required at the entry to the landfill;
(ii) Monitor groundwater according to WAC
173-304-490 using a design
approved by the local jurisdictional health department with the guidance of the
department. The jurisdictional health department may also require monitoring
of:
(A) Surface waters, including
runoff;
(B) Leachate;
(C) Subsurface landfill gas movement and
ambient air; and
(D)
Noise.
(iii) Weigh all
incoming waste on scales for landfills having a permitted capacity of greater
than ten thousand cubic yards per year or provide an equivalent method of
measuring waste tonnage capable of estimating total annual solid waste tonnage
to within plus or minus five percent;
(iv) Provide for employee facilities
including shelter, toilets, hand washing facilities and potable drinking water
for landfills having the equivalent of three or more full-time
employees;
(v) Erect a sign at the
site entrance that identifies at least the name of site, if applicable, the
hours during which the site is open for public use, unacceptable materials and
an emergency telephone number. Other pertinent information may be required by
the jurisdictional health department;
(vi) Provide on-site fire protection as
determined by the local and state fire control jurisdiction;
(vii) Prevent potential rat and other vectors
(such as insects, birds, and burrowing animals) harborage in buildings,
facilities, and active areas;
(viii) Provide the unloading area(s) to be as
small as possible, consistent with good traffic patterns and safe
operation;
(ix) Provide approach
and exit roads to be of all-weather construction, with traffic separation and
traffic control on-site, and at the site entrance; and
(x) Provide communication between employees
working at the landfill and management offices on-site and offsite (such as
telephones) to handle emergencies.
(4) Minimum functional standards for maintenance and operation.
(a) Operating
plans. All owners or operators of landfills shall maintain and operate the
facility so as to conform to the approved plan of operation.
(b) Operating details. All owners or
operators of landfills shall operate the facility so as to:
(i) Control road dust;
(ii) Perform no open burning unless permitted
by the jurisdictional air pollution control agency or the department under the
Washington Clean Air Act,
chapter
70.94 RCW. Garbage shall
not be open burned.
(iii) Collect
scattered litter as necessary to avoid a fire hazard or an aesthetic
nuisance;
(iv) Prohibit
scavenging;
(v) Conduct on-site
reclamation in an orderly sanitary manner, and in a way that does not interfere
with the disposal site operation;
(vi) Insure that at least two landfill
personnel are on-site with one person at the active face when the site is open
to the public for landfills with a permitted capacity of greater than fifty
thousand cubic yards per year;
(vii) Control insects, rodents and other
vectors; and
(viii) Insure that
reserve operational equipment shall be available to maintain and meet these
standards.
(c) Boundary
posts. All owners or operators of landfills shall clearly mark the active area
boundaries authorized in the permit, with permanent posts or using equivalent
method clearly visible for inspection purposes.
(d) Compaction and daily cover. All owners or
operators of landfills shall:
(i) Thoroughly
compact the solid waste before succeeding layers are added; and
(ii) Cover compacted waste containing garbage
fully with at least six inches of compacted cover material after each day of
operation. The jurisdictional health department may allow less frequent
covering by considering:
(A) The
characteristics of the solid waste;
(B) The climatic and geologic
setting;
(C) The size of the
facility; and
(D) The potential for
nuisance conditions.
(e) Monitoring systems. All owners and
operators of landfills shall maintain the monitoring system required in
subsection (3)(g)(ii) of this section.
(f) Recycling required.
(i) All owners or operators of landfills at
which the general public delivers household solid waste shall provide the
opportunity for the general public to recycle cans, bottles, paper and other
material for which a market exists and brought to the landfill site:
(A) During the normal hours of
operation;
(B) In facilities
convenient to the public (i.e., near entrance to the gate).
(ii) Owners or operators may
demonstrate alternative means to providing an opportunity to the general public
to recycle household solid waste.
(g) Disposal of dangerous waste prohibited.
Owners or operators of landfills shall not knowingly dispose, treat, store, or
otherwise handle dangerous waste unless the requirements of the dangerous waste
regulation, chapter 173-303 WAC are met.
(5) Limited purpose landfill standards.
(a) Limited purpose landfills shall meet the
following requirements:
(i) The general
facility standards of WAC
173-304-405;
(ii) The general closure and post-closure
standards of WAC
173-304-407;
(iii) The performance standards of WAC
173-304-460(2);
(iv) The financial assurance standards of WAC
173-304-467 and
173-304-468; and
(v) The groundwater monitoring standards of
WAC 173-304-490.
(b) In addition, limited purpose landfills
must meet all other standards of WAC
173-304-130 and
173-304-460 unless the owner or
operator applies for relief from each of these requirements as part of his
permit application and includes evidence or reasons why the nature of the
waste, the disposal site and other factors can protect the environment and the
public health.
Statutory Authority: RCW 70.95.215. 88-20-066 (Order 88-28), § 173-304-460, filed 10/4/88. Statutory Authority: Chapter 43.21A RCW. 85-22-013 (Order 85-18), § 173-304-460, filed 10/28/85.
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