For purposes of this part, in cases where a definition does not exist in this part or WAC 173-204-200 the definitions in chapter 173-340 WAC will apply unless the context indicates otherwise. For the purpose of this part, the following definitions shall apply:

(1) "Active cleanup action" means a cleanup action requiring physical construction to achieve sediment cleanup standards. Active cleanup actions include dredging, capping, treatment, and enhanced natural recovery. Passive cleanup actions such as monitored natural recovery and institutional controls are not active cleanup actions for purposes of sediment cleanup only.

(2) "Applicable laws" means all legally applicable requirements specified in WAC 173-340-710(3) and those requirements that the department determines, based on the criteria in WAC 173-340-710(4), are relevant and appropriate requirements. Relevant and appropriate requirements may also include those requirements established under local or tribal laws that the department determines meet the criteria in WAC 173-340-710(4).

(3) "Beneficial reuse" means reuse of sediment from the site, or a separated portion of the sediment (such as the gravel fraction), that utilizes the physical characteristics and properties of the sediment in place of other material without requiring the use of engineered or institutional controls to protect human health or the environment. Examples of beneficial reuse include habitat restoration or enhancement, mine reclamation, landfill cover material, asphalt or concrete aggregate, or use of organic fines in manufactured topsoil.

(4) "Biologically active zone" means the sediment depth determined by the department where the species critical to the function, diversity, and integrity of the benthic community are located. Metrics such as biomass and abundance may be used to define the vertical extent of the biologically active zone. These species can include endemic and keystone animals, plants, or other species. Abiotic factors such as groundwater upwelling, salt wedges, water temperature, dissolved oxygen, and hyporheic flow can affect the vertical distribution of organisms in the biologically active zone.

(5) "Cleanup action" means any remedial action, except an interim action, taken at a sediment site or sediment cleanup unit to eliminate, render less toxic, stabilize, contain, immobilize, isolate, treat, destroy, or remove contaminants that complies with sediment cleanup standards and other applicable laws. A remedial action that does not comply with sediment cleanup standards and other applicable laws is an interim action.

(6) "Cleanup screening level" means the maximum allowed concentration of any contaminant and level of biological effects permissible at the site or sediment cleanup unit per procedures in WAC 173-204-560(4) after completion of the cleanup action. Cleanup screening levels are also used to identify and assess the hazard of sites under WAC 173-204-510 and 173-204-520.

(7) "Contaminant" means any hazardous substance that does not occur naturally or occurs at greater than natural background levels.

(8) "Enhanced natural recovery" means a cleanup action that uses human intervention to accelerate the process of natural recovery. An example of enhanced natural recovery is the placement of a thin clean layer of sediment over an area of contaminated sediment to naturally mix with the contaminated sediment and reduce the contaminant concentrations or toxicity followed by a period of monitoring to determine the effectiveness.

(9) "Include" means included, but not limited to.

(10) "Monitored natural recovery" means a cleanup action that is a form of natural recovery that includes regular monitoring of sediment quality, tissue, benthic infauna, and/or biota as appropriate to assess the effectiveness of natural recovery to restore sediment quality.

(11) "Natural background" means the concentration of a hazardous substance consistently present in the environment that has not been influenced by localized human activities. For example, several metals and radionuclides naturally occur in the bedrock, sediment, and soil of Washington state due solely to the geologic processes that formed these materials and the concentration of these hazardous substances would be considered natural background. Also, low concentrations of some particularly persistent organic compounds such as polychlorinated biphenyls (PCBs) can be found in surficial soils and sediment throughout much of the state due to global distribution of these hazardous substances. These low concentrations would be considered natural background. Similarly, concentrations of various radionuclides that are present at low concentrations throughout the state due to global distribution of fallout from bomb testing and nuclear accidents would be considered natural background.

(12) "Natural recovery" means physical, chemical or biological processes that act, without human intervention, to reduce the toxicity or concentration of contaminated sediment. An example of natural recovery is the natural deposition of a layer of clean sediment over an area of contaminated sediment resulting in burial over time of contaminated sediment below the biologically active zone. The natural process of sediment mixing, and degradation of some contaminants, such as polycyclic aromatic hydrocarbons, can also contribute to natural recovery.

(13) "Point of compliance" means the locations within a site or sediment cleanup unit where sediment cleanup levels must be met.

(14) "Practicable" means capable of being designed, constructed and implemented in a reliable and effective manner including consideration of cost. When considering cost under this analysis, an alternative shall not be considered practicable if the incremental costs of the alternative are disproportionate to the incremental degree of benefits provided by the alternative over other lower cost alternatives.

(15) "Practical quantitation limit" means the lowest concentration that can be reliably measured within specified limits of precision, accuracy, representativeness, completeness, and comparability during routine laboratory operating conditions, using department approved methods. When the limit for an analytical method is higher than the concentrations based on protection of human health or the environment, the department may require the use of another method to lower the practical quantitation limit.

(16) "Regional background" means the concentration of a contaminant within a department-defined geographic area that is primarily attributable to diffuse sources, such as atmospheric deposition or stormwater, not attributable to a specific source or release. See WAC 173-204-560(5) for the procedures and requirements for establishing regional background.

(17) "Sediment cleanup level" means the concentration or level of biological effects for a contaminant in sediment that must be achieved and is determined by the department to be protective of human health and the environment under the authority of chapter 70.105D RCW. The sediment cleanup level can be established between the sediment cleanup objective and cleanup screening level in accordance with the requirements in WAC 173-204-560(2).

(18) "Sediment cleanup objective" means the goal for protection of human health and the environment and is established under the authority of chapter 70.105D RCW. The sediment cleanup objective is established in accordance with the requirements in WAC 173-204-560(3). Sediment cleanup objectives are also used to identify and assess the hazard of sites under WAC 173-204-510 and 173-204-520.

(19) "Sediment cleanup standard" means the standards adopted under RCW 70.105D.030 (2)(e). Establishing sediment cleanup standards requires specification of the following:

(a) The chemical concentration or level of biological effects for a contaminant in sediment that is determined by the department to be protective of human health and the environment (sediment cleanup level);

(b) The location at the site or sediment cleanup unit where those sediment cleanup levels must be achieved (point of compliance); and

(c) Additional regulatory requirements that apply to a cleanup action because of the type of action and/or the location of the site. These requirements are specified in applicable laws and are generally established in conjunction with the selection of a specific cleanup action.

(20) "Sediment cleanup unit" means a discrete subdivision of a sediment site designated by the department for the purpose of expediting cleanups. A sediment cleanup unit may be established based on unique chemical concentrations or parameters, regional background, environmental, spatial, or contaminant source characteristics, or other methods determined appropriate by the department, e.g., development-related cleanups, cleanup under piers, cleanup in eelgrass beds, and cleanup in navigational lanes.

(21) "Sediment recovery zone" means an area authorized by the department within a site or sediment cleanup unit where the department has determined the cleanup action cannot achieve the applicable sediment cleanup standards within ten years after completion of construction of the active components of the cleanup action. Sediment recovery zones must meet the requirements in WAC 173-204-590 and be authorized by the department under WAC 173-204-575.

(22) "Surface sediment" or "sediment" means settled particulate matter located at or below the ordinary high water mark, where the water is present for a minimum of six consecutive weeks, to which biota (including benthic infauna) or humans may potentially be exposed, including that exposed by human activity (e.g., dredging).

(23) "Technically possible" means capable of being designed, constructed and implemented in a reliable and effective manner, regardless of cost.