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 173-304-430 - Surface impoundment standards
Universal Citation: WA Admin Code 173-304-430
Current through Register Vol. 24-06, March 15, 2024
(1) Applicability.
(a) These standards are applicable to solid
wastes that are liquids or sludges containing free liquids as defined in WAC
173-304-100 and applicable under
WAC 173-304-015(2)
and are stored or treated in surface impoundments;
(b) These standards are also applicable to
sludges and septage stored or treated in surface impoundments; and
(c) These standards are not applicable to:
(i) Surface impoundments whose facilities and
discharges are otherwise regulated under federal, state, or local water
pollution permits; and
(ii)
Retention or detention basins used to collect and store stormwater
runoff.
(2) Requirements. All surface impoundments must be designed, constructed, and operated so as to:
(a) Meet the performance
standards of WAC
173-304-460(2);
(b) Have an inplace or imported soil liner of
at least two feet of 1 x 10-7 cm/sec permeability or
an equivalent combination of any thickness greater than two feet and a greater
permeability to protect the underlying aquifers or a thirty mil reinforced
artificial liner placed on top of a structurally stable foundation to support
the liners and solid waste and to prevent settlement that would destroy the
liner; natural soils shall be recompacted to achieve an equivalent
permeability. Owners or operators shall be allowed to use alternative designs,
operating practices and locational characteristics which prevent migration of
solid waste constituents or leachate into the ground or surface waters at least
as effectively as the liners described in this subsection;
(c) Avoid washout including the use of an
extended liner or dikes or restriction of flow in the one hundred year flood
plain and to comply with local flood plain management ordinances and chapter
508-60 WAC, Administration of flood control zones;
(d) Have dikes designed with slopes so as to
maintain the structural integrity under conditions of a leaking liner and
capable of withstanding erosion from wave action;
(e) Have the freeboard equal to or greater
than eighteen inches to avoid overtopping from wave action, overfilling, or
precipitation;
(f) Have either a
groundwater monitoring system, or a leachate detection, collection and
treatment system, for surface impoundments having a capacity of more than two
million gallons unless the jurisdictional health department and the department
require either for smaller surface impoundments. For purposes of this
subsection, capacity refers to the total capacity of all surface impoundments
on-site (i.e., two, one million gallon surface impoundments on one site will
trigger these monitoring requirements);
(g) Be closed in a manner which removes all
solid wastes including liners, etc. to another permitted facility and the site
returned to its original or acceptable topography except that surface
impoundments closed with the waste remaining in place shall meet the
requirements of WAC
173-304-407 and
173-304-130;
(h) A jurisdictional health department may
require that the liner be inspected for wear and integrity and repaired or
replaced by removing stored solid wastes or otherwise inspecting the liner or
base at any time. The request shall be in writing and cite the reasons
including valid groundwater monitoring or leachate detection data leading to
such an inspection and repair;
(i)
Surface impoundments containing septage will also be subject to the
department's "criteria for sewage works design" used to review plans for
septage surface impoundments; and
(j) Surface impoundments that have the
potential to impound more than ten acre-feet of waste measured from the top of
the dike and which would be released by a failure of the containment dike shall
be reviewed and approved by the dam safety section of the department.
Statutory Authority: RCW 70.95.215. 88-20-066 (Order 88-28), § 173-304-430, filed 10/4/88. Statutory Authority: Chapter 43.21A RCW. 85-22-013 (Order 85-18), § 173-304-430, filed 10/28/85.
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