| (78) Sample detection limit--The method detection limit, as defined in this section, adjusted to reflect sample-specific actions, such as dilution or use of smaller aliquot sizes than prescribed in the analytical method, and to take into account sample characteristics, sample preparation, and analytical adjustments. The term, as used in this rule, is analogous to the sample-specific detection limit. (79) Sediment--Non-suspended particulate material lying below surface waters such as bays, the ocean, rivers, streams, lakes, ponds, or other similar surface water body (including intermittent streams). Dredged sediments which have been removed from below surface water bodies and placed on land shall be considered soils. (80) Selected ecological receptors--Species that are to be carried through the ecological risk assessment as representatives of the different feeding guilds and communities that are being evaluated. These species may not actually occur at the affected property, but may be used to represent those within the feeding guild or community that may feed on the affected property. (81) Sensitive environmental areas--Areas that provide unique and often protected habitat for wildlife species. These areas are typically used during critical life stages such as breeding, hatching, rearing of young, and overwintering. Examples include critical habitat for threatened and endangered species, wilderness areas, parks, and wildlife refuges. (82) Soil protective concentration level exceedence zone--A protective concentration level exceedence zone within the surface soil or subsurface soil which may extend down to a groundwater-bearing unit(s). These protective concentration level exceedence zones may also be present below or between groundwater-bearing units. (83) Source area--The volume of a chemical of concern in environmental media (e.g., soil or groundwater) which is leaching, dissolving or emitting chemicals of concern. Of primary regulatory concern are the source areas that are leaching, dissolving or emitting chemicals of concern at unprotective concentrations under natural conditions, and not in consideration of any physical controls (e.g., slurry walls, caps), that will result in protective concentrations being exceeded at the point of exposure. The source area need not be the horizontal and vertical extent of the protective concentration level exceedence zone when cross-media or lateral chemical of concern transport is required for a point of exposure to be reached. Generally, a source area is located in the vicinity of or below primary release sources (e.g., tanks, pipelines, drums, lagoons, landfills, etc.). (84) Source medium--An environmental medium containing chemicals of concern which must be removed, decontaminated and/or controlled in order to protect human health and the environment. The source medium may be the exposure medium for some exposure pathways. (85) Stressor--Any physical, chemical, or biological entity that can induce an adverse response; however, as used in this context, only chemical entities apply. (86) Subsurface soil--For human health exposure pathways, the portion of the soil zone between the base of surface soil and the top of the groundwater-bearing unit(s). For ecological exposure pathways, the portion of the soil zone between 0.5 feet and 5 feet in depth. (87) Surface cover--A layer of artificially placed utility material (e.g., shell, gravel). (88) Surface soil--For human health exposure pathways, the soil zone extending from ground surface to 15 feet in depth for residential land use and from ground surface to 5 feet in depth for commercial/industrial land use; or to the top of the uppermost groundwater-bearing unit or bedrock, whichever is less in depth. For ecological exposure pathways, the soil zone extending from ground surface to 0.5 feet in depth. (89) Surface water--Any water meeting the definition of surface water in the state as defined in §307.3 of this title (relating to Definitions and Abbreviations), as amended. (90) Toxicity reference value--An exposure level from a valid scientific study that represents a conservative threshold for adverse ecological effects. (91) Waste control unit--A municipal or industrial solid waste landfill, including those Resource Conservation and Recovery Act regulated units closed as landfills, with a liner system (i.e., synthetic or clay) and an engineered cap, that have been closed pursuant to an approved closure plan, previous regulations, or will be implemented pursuant to an approved response action plan. (b) Acronyms. (1) APAR--Affected property assessment report; (2) COC--Chemical of concern; (3) FOA--Facility Operations Area; (4) Kd --Soil-water partition coefficient; (5) Koc --Octanol-water partition coefficient; (6) LOAEL--Lowest observed adverse effect level; (7) MCL--Maximum contaminant level; (8) NAPLs--Nonaqueous phase liquids; (9) NOAEL--No observed adverse effect level; (10) PCL--Protective concentration level; (11) PCLE zone--Protective concentration level exceedence zone; (12) POE--Point of exposure; (13) PRACR--Post-response action care report; (14) RACR--Response action completion report; (15) RAER--Response action effectiveness report; (16) RAP--Response action plan; (17) RBEL--Risk-based exposure limit; (18) SIN--Self-implementation notice; (19) TAC--Texas Administrative Code; (20) TCEQ--Texas Commission on Environmental Quality; (21) TPDES--Texas Pollutant Discharge Elimination System; and (22) U.S. EPA--United States Environmental Protection Agency. (c) Risk-based exposure limit nomenclature. A nomenclature is used in Subchapter D of this chapter (relating to the Development of Protective Concentration Levels) to refer to specific RBELs. The RBEL nomenclature reflects the exposure medium and the exposure route. The exposure medium appears first in superscript text, followed by RBEL in regular text and lastly the exposure route in subscript text. For example Soil RBELIng is a RBEL where soil is the exposure medium and ingestion is the exposure route. (1) Air RBEL Inh --air inhalation RBEL; (2) Soil RBEL Derm --dermal contact with soil RBEL; (3) Soil RBEL Ing --ingestion of soil RBEL; (4) GW RBEL Ing --ingestion of groundwater RBEL; (5) GW RBEL Class 3 --class 3 groundwater RBEL; (6) SW RBEL--surface water RBEL; (7) AbgVeg RBEL Ing --ingestion of aboveground vegetables RBEL; and (8) BgVeg RBEL Ing --ingestion of below-ground vegetables RBEL. (d) Protective concentration level nomenclature. A nomenclature is used in Subchapter D of this chapter (relating to the Development of Protective Concentration Levels) to refer to specific PCLs. The PCL nomenclature reflects the exposure medium, source medium and the exposure route. The exposure medium appears first in superscript text, followed by the source medium in regular text and lastly the exposure route in subscript text. For example, GW GWIng is a PCL where groundwater is the source medium (GW), groundwater is the exposure medium ( GW ), and ingestion is the exposure route (Ing ). Cross-media transfer is indicated when exposure occurs in a different medium than the source medium. For example, Air SoilInh-V is a PCL where soil is the source medium and air is the exposure medium. (1) GW GW Ing --PCL for groundwater ingestion; (2) GW GW Class 3 --PCL for class 3 groundwater; (3) Air GW Inh-V --PCL for inhalation of volatiles from groundwater; (4) SW GW--PCL for groundwater discharge to surface water; (5) Tot Soil Comb --surface soil PCL for combined soil ingestion, dermal contact, inhalation of volatiles and particulates, and for residential land use, ingestion of aboveground and below-ground vegetables; (6) Air Soil Inh-VP --PCL for inhalation of volatiles and particulates from surface soil; (7) Soil Soil Derm --PCL for dermal contact with surface soil; (8) Soil Soil Ing --PCL for ingestion of surface soil; (9) Veg Soil Ing-Inorg --surface soil PCL for ingestion of inorganic COCs in vegetables; (10) Veg Soil Ing-Org --surface soil PCL for ingestion of organic COCs in vegetables; (11) GW Soil--PCL for surface and subsurface soil to protect groundwater; (12) Air Soil Inh-V --PCL for inhalation of volatiles from subsurface soil; (13) Air Air Inh --air PCL for inhalation; and (14) SW SW--surface water PCL. |
