(1)(a) In accordance with the requirements of this section and WAC 173-303-64610 through 173-303-64630, the department may designate an area at a facility as a corrective action management unit for the purpose of treating, storing or disposing of remediation waste that originates at the same facility in order to implement remedies under this section or to implement other cleanup actions. Corrective action management unit means an area within a facility that is used only for managing remediation wastes for implementing corrective action or cleanup at the facility. A CAMU must be located within the contiguous property under the control of the owner or operator where the wastes to be managed in the CAMU originated. One or more CAMUs may be designated at a facility.

(b) Designation of a CAMU will not in any way affect the department's existing authorities, including authority under chapter 70.105D RCW, to address clean-up levels, media-specific points of compliance, or other remedy selection decisions.

(c) Designation of a CAMU will not in any way affect the timing or scope of review of any actions taken under the Model Toxics Control Act pursuant to WAC 173-303-64630 to fulfill the corrective action requirements of WAC 173-303-64620 or the corrective action requirements of WAC 173-303-645.

(2) Designation of a corrective action management unit.

(a) When designating a CAMU, the director will do so in accordance with the following:

(i) The CAMU will facilitate the implementation of reliable, effective, protective, and cost-effective remedies;

(ii) Waste management activities associated with the CAMU will not create unacceptable risks to humans or the environment resulting from exposure to dangerous wastes or dangerous constituents;

(iii) The CAMU will include uncontaminated areas of the facility only if including such areas for the purposes of managing remediation wastes is more protective than management of such wastes at contaminated areas of the facility;

(iv) Areas within the CAMU where wastes remain in place after closure of the CAMU, will be managed and contained so as to minimize future releases of dangerous wastes and dangerous constituents to the extent practicable;

(v) When appropriate and practicable, the CAMU will expedite the timing of remedial activity implementation;

(vi) The CAMU will enable the use, when appropriate, of treatment technologies (including innovative technologies) to enhance the long-term effectiveness of remedial actions by reducing the toxicity, mobility, or volume of wastes that will remain in place after closure of the CAMU; and

(vii) The CAMU will, to the extent practicable, minimize the land area of the facility upon which wastes will remain in place after closure of the CAMU.

(b) When designating a CAMU, the director will specify requirements for the CAMU including the following:

(i) The areal configuration of the CAMU;

(ii) Requirements for remediation waste management within the CAMU including specification of applicable design, operation, and closure requirements;

(iii) Requirements for groundwater and vadose zone monitoring that are sufficient to:

(A) Continue to detect and to characterize the nature, extent, concentration, direction, and movement of existing releases of dangerous waste and dangerous constituents in groundwater from sources located within the CAMU; and

(B) Detect and subsequently characterize releases of dangerous waste and dangerous constituents to groundwater that may occur from areas of the CAMU in which wastes will remain in place after CAMU closure.

(iv) Requirements for closure that will minimize the need for further maintenance of the CAMU; and control, minimize, or eliminate to the extent necessary to protect human health and the environment, for areas where wastes remain in place, post-closure escape of dangerous waste, dangerous constituents, leachate, contaminated runoff, or dangerous waste decomposition products to the ground, to groundwaters, to surface waters, or to the atmosphere and will include, as appropriate and deemed necessary by the director, the following:

(A) Requirements for excavation, removal, treatment, and/or containment of wastes;

(B) For areas in which wastes will remain after closure of the CAMU, requirements for capping of such areas; and

(C) Requirements for removal and decontamination of equipment, devices, and structures used in remediation waste management activities within the CAMU.

(c) In establishing closure requirements for CAMUs under (b)(iv) of this subsection, the director will consider the following factors:

(i) CAMU characteristics;

(ii) Volume of wastes which will remain in place after CAMU closure;

(iii) Potential for releases from the CAMU;

(iv) Physical and chemical characteristics of the waste;

(v) Hydrological and other relevant environmental conditions at the facility which may influence the migration of any potential or actual releases in and/or from the CAMU; and

(vi) Potential for exposure of humans and environmental receptors if releases were to occur at or from the CAMU.

(d) The director will, for areas of the CAMU in which wastes will remain in place after CAMU closure, specify post-closure requirements to control, minimize, or eliminate, to the extent necessary to protect human health and the environment, post-closure escape of dangerous waste, dangerous constituents, leachate, contaminated runoff, and dangerous waste decomposition products to the ground, to groundwaters, to surface waters, and to the atmosphere. Such post-closure requirements will include, as necessary to protect human health and the environment, monitoring and maintenance activities and the frequency with which such activities will be performed to ensure the integrity of any cap, final cover, or other containment system.

(e) The owner/operator of a facility must provide sufficient information to enable the director to designate a CAMU in accordance with the criteria in WAC 173-303-64650, 173-303-64660, and 173-303-64670.

(f) The director will document the rationale for designating CAMUs and will make such documentation available to the public.

(g) Incorporation of the designation of and requirements for a CAMU into an existing permit must be approved by the director according to the procedures for agency initiated permit modifications under WAC 173-303-830(3), or according to the permit modification procedures of WAC 173-303-830(4).

(3) Incorporation of a regulated unit within a CAMU.

(a) The director may designate a regulated unit (as defined in WAC 173-303-040) as a CAMU, or may incorporate a regulated unit into a CAMU, if:

(i) The regulated unit is closed or closing, meaning it has begun the closure process under WAC 173-303-610(4) or 40 C.F.R. Part 265.113, which is incorporated by reference at WAC 173-303-400 (3)(a); and

(ii) Inclusion of the regulated unit will enhance implementation of effective, protective and reliable remedial actions at the facility.

(b) The requirements of WAC 173-303-610, 173-303-620, 173-303-645, and the unit specific requirements of WAC 173-303-650 through 173-303-680 that applied to the regulated unit will continue to apply to the portion of the CAMU into which the regulated unit was incorporated.