WAC 173-304-460
Landfilling standards. (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) Ground water. An owner or operator of a landfill
shall not contaminate the ground water 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 off-site 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 run-off, 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 run-off 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 ground water 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 lockable gate
shall be required at the entry to the landfill;
(ii) Monitor ground water 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 run-off;
(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) harborages 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 off-site (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 ground water 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.]