| (35) Exposure pathway--The course that a chemical of concern takes from a source area to ecological or human receptors and includes a source area, a point of exposure, and an exposure route (e.g., ingestion), as well as a transport mechanism if the point of exposure is different from the source area. (36) Facility--The installation associated with the affected property where the release of chemicals of concern occurred. (37) Facility Operations Area--One or more areas (lateral and vertical extent) of an operational chemical or petroleum manufacturing plant with North American Industrial Classification System code numbers 325 or 324, respectively, with a hazardous waste permit or commission corrective action order within which response actions to multiple releases of COCs can be consolidated for purposes of compliance with this chapter on an area-wide basis by using interim or permanent response actions. The lateral extent of the facility operations area is limited to the contiguous area actively used for the development, manufacture, process, transfer, storage, and management of chemical or refinery products, hazardous materials, substances and wastes subject to Resource Conservation and Recovery Act regulation, and includes ancillary components such as, but not necessarily limited to, power plants and cooling units. (38) Feeding guilds--Groups of ecological receptors used to represent the variety of species that may be exposed to chemicals of concern at the affected property. The feeding guilds are generally based on function within an ecosystem, potential for exposure, and physiological and taxonomic similarity. Examples include carnivorous mammals, carnivorous birds, and piscivorous birds. (39) Functioning cap--A low permeability layer or other approved cover meeting its design specifications to minimize water infiltration and chemical of concern migration, and prevent ecological or human receptor exposure to chemicals of concern, and whose design requirements are routinely maintained. (40) Groundwater-bearing unit--A saturated geologic formation, group of formations, or part of a formation which has a hydraulic conductivity equal to or greater than 1 x 10-5 centimeters/second. (41) Groundwater production zone--The groundwater-bearing unit(s) which contributes water to a well. For example, if a well penetrates four distinct groundwater-bearing units isolated by competent aquitards, but the well is screened in only two of the units and has a competent annular seal to isolate the other two units, then the groundwater production zone consists of only the two units that contribute water to the well. (42) Groundwater protective concentration level exceedence zone--A protective concentration level exceedence zone within a groundwater-bearing unit. (43) Hazard index--The sum of two or more hazard quotients for multiple noncarcinogens originating from a single affected property. (44) Hazard quotient--The ratio of the level of exposure of a noncarcinogen acting through an individual or combined exposure pathway over a specified time period to a reference dose for the noncarcinogen derived for a similar exposure period. (45) Implementation Procedures--The most current version of Procedures to Implement the Texas Surface Water Quality Standards, as amended. (46) Innocent Owner or Operator--Those persons so designated in accordance with Texas Health and Safety Code, Chapter 361, Subchapter V, Immunity From Liability of Innocent Owner or Operator, as amended. (47) Institutional control--A legal instrument placed in the property records in the form of a deed notice, Voluntary Cleanup Program Certificate of Completion (VCP Certificate of Completion), or restrictive covenant which indicates the limitations on or the conditions governing use of the property which ensures protection of human health and the environment or equivalent zoning and governmental ordinances. (48) Judgmental sample--An investigative sample of an environmental medium which is purposefully located based upon property-specific information. (49) Laboratory Control Sample--A spiked blank sample analyzed by the laboratory to assess laboratory ability to successfully recover chemicals of concern from a control matrix. (50) Landscaped area--An area of ornamental, introduced, commercially installed, or manicured vegetation which is routinely maintained. (51) Long-term effectiveness--The ability of a remedy to maintain the required level of protection of human health and the environment over time. (52) Lower explosive limit--The lowest concentration of a vapor or gas in air that will produce a flash of fire when an ignition source (heat, arc, or flame) is present. (53) Method detection limit--The minimum concentration of a substance that can be measured and reported with 99% confidence that the analyte concentration is greater than zero and is determined for each COC from the analysis of a sample of a given matrix type containing the COC. (54) Method quantitation limit--The lowest non-zero concentration standard in the laboratory's initial calibration curve and is based on the final volume of extract (or sample) used by the laboratory. (55) Monitored natural attenuation--The use of natural attenuation within the context of a carefully controlled and monitored response action to achieve protective concentration levels at the point of exposure. (56) Natural attenuation--The reduction in mass or concentration of a chemical of concern over time or distance from the source of a chemical of concern due to naturally occurring physical, chemical, and biological processes, such as: biodegradation, dispersion, dilution, adsorption, and volatilization. (57) Natural attenuation factor--The numerical value which represents the natural attenuation (i.e., reduction) in chemical of concern concentrations during transport from the source area to the point of exposure. The natural attenuation factor is the concentration at the source area divided by the concentration at the point of exposure. The natural attenuation factor is always greater than or equal to one for the purposes of this rule. (58) Natural Resource Trustees--The federal agencies as designated by the President and the state agencies as designated by the Governor pursuant to the National Contingency Plan, Oil Pollution Act, and CERCLA §107(f)(2)(A) and (B) to act on behalf of the public as trustees of natural resources (e.g., water, air, land, wildlife). The Trustees include TCEQ, Texas Parks and Wildlife Department, Texas General Land Office, National Oceanic and Atmospheric Administration, and the Department of the Interior. (59) Off-site property (off-site)--All environmental media which is outside of the legal boundaries of the on-site property. (60) On-site property (on-site)--All environmental media within the legal boundaries of a property owned or leased by a person who has filed a self-implementation notice or a response action plan for that property or who has become subject to such action through one of the agency's program areas for that property. (61) Permanence/permanent/permanently--The property of a response action which is capable of enduring indefinitely without posing the threat of any future release of chemicals of concern above the critical protective concentration levels established for the property. (62) Person--An individual, corporation, organization, government or governmental subdivision or agency, business trust, partnership, association, or any other legal entity. (63) Physical barrier--Any structure or system, natural or manmade, that prevents exposure or prevents migration of chemicals of concern to the points of exposure. (64) Physical control--A structure or hydraulic containment action which prevents exposure to and/or migration of chemicals of concern when combined with appropriate post-response action care to protect human health and the environment. Examples of physical controls are caps, slurry walls, sheet piling, hydraulic containment wells, and interceptor trenches, but typically not fences. (65) Plume management zone--The area of the groundwater protective concentration level exceedence zone at the time of response action plan submittal, plus any additional area allowed in accordance with §350.33(f)(4) of this title (relating to Remedy Standard B). (66) Point of exposure--The location within an environmental medium where a receptor will be assumed to have a reasonable potential to come into contact with chemicals of concern. The point of exposure may be a discrete point, plane, or an area within or beyond some location. (67) Prescribed points of exposure--The prescribed on-site and off-site locations within an environmental medium where an individual human or population will be assumed to come into contact with chemicals of concern from an affected property. Cont'd... |
