Washington Administrative Code
Title 173 - Ecology, Department of (See also Titles 197, 317, 372, and 508)
Chapter 173-351 - Criteria for municipal solid waste landfills
Section 173-351-300 - Design criteria
Current through Register Vol. 24-06, March 15, 2024
(1) Applicability. New MSWLF units and lateral expansions must be constructed in accordance with the requirements under subsection (2) of this section. Existing MSWLF units are not subject to this section. Waste placement in existing units must be consistent with past operating practices or modified practices to ensure good management, including operating plans approved under chapter 173-304 WAC.
(2) New MSWLF units and lateral expansions must be constructed:
(3) For the purpose of this section, "composite liner" means a system consisting of two components; the upper component must consist of a minimum of 60 mil thickness high density polyethylene (HDPE) geomembrane. The lower component must consist of at least a two-foot (60 cm) layer of compacted soil with a hydraulic conductivity of no more than 1X10-7 cm/sec. The geomembrane must be installed in direct and uniform contact with the compacted soil component. Thinner geomembranes of other than high density polyethylene may be used provided that a demonstration can be made that the alternative has equivalent mechanical strength, permeability, chemical resistance and other factors under conditions of construction and use. Minimum thickness of geomembranes other than high density polyethylene must be 30 mils.
(4) When demonstrating that a proposed alternative design meets the standards of this section, the owner or operator may use:
(5) When approving an alternative design, the jurisdictional health department must consider at least the following factors:
(6) The relevant point of compliance approved during the permitting process in WAC 173-351-700 or through the permit modification process of WAC 173-351-720(6), must be no more than one hundred fifty meters (four hundred ninety-two feet) from the waste management unit boundary and must be located on land owned by the owner of the MSWLF unit. In approving the relevant point of compliance the jurisdictional health department must consider at least the following factors:
(7) Liner separation from groundwater. New MSWLF units and lateral expansions may not be designed such that the bottom of the lowest liner component is any less than ten feet (three meters) above the seasonal high level of groundwater, unless a demonstration can be made during the permit process of WAC 173-351-700 or through the permit modification process of WAC 173-351-720(6) that a hydraulic gradient control system, or the equivalent, can be installed which prevents the controlled seasonal high level of groundwater in the identified water-bearing unit from contacting the bottom of the lowest liner component. For the purposes of this section, groundwater includes any water-bearing unit that is horizontally and vertically extensive, hydraulically recharged and volumetrically significant as to harm or endanger the integrity of the liner at any time. The owner or operator must place the demonstration in the application for a permit under WAC 173-351-700 or through the permit modification process of WAC 173-351-720(6). This demonstration must include:
TABLE 1
CHEMICAL |
Maximum Concentration (mg/l) |
ARSENIC |
0.00005 |
BARIUM |
1.0 |
BENZENE |
0.001 |
CADMIUM |
0.005 |
CARBON TETRACHLORIDE |
0.0003 |
CHROMIUM (HEXAVALENT) |
0.05 |
2,4-DICHLOROPHENOXY ACETIC ACID |
0.07 |
1,4-DICHLOROBENZENE |
0.004 |
1,2-DICHLOROETHANE |
0.0005 |
1,1 DICHLOROETHYLENE |
0.007 |
ENDRIN |
0.0002 |
FLUORIDE |
4 |
LINDANE |
0.00006 |
LEAD |
0.015 |
MERCURY |
0.002 |
METHOXYCHLOR |
0.04 |
NITRATE |
10 |
SELENIUM |
0.01 |
SILVER |
0.05 |
TOXAPHENE |
0.00008 |
1,1,1-TRICHLOROETHANE |
0.20 |
TRICHLOROETHYLENE |
0.003 |
2,4,5-TRICHLOROPHENOXY ACETIC ACID |
0.01 |
VINYL CHLORIDE |
0.00002 |
Statutory Authority: RCW 70.95.020(3), 70.95.060(1), and 70.95.260(1), (6). 12-23-009 (Order 07-15), § 173-351-300, filed 11/8/12, effective 12/9/12. Statutory Authority: Chapter 70.95 RCW and 40 CFR 258. 93-22-016, § 173-351-300, filed 10/26/93, effective 11/26/93.