The person shall use the following groundwater resource classification system to classify each groundwater-bearing unit which contains COCs at concentrations equal to or greater than the residential groundwater assessment level. The person shall submit data which support the groundwater resource classification in an affected property assessment report. If a groundwater-bearing unit meets the criteria for more than one of the following classifications, then the person shall assign the higher of the classifications (e.g., if a groundwater-bearing unit falls in class 1 and class 3, it will be classified as class 1), unless otherwise approved by the executive director.
  (1) Class 1 groundwater resource. To be considered a class 1 groundwater resource, the groundwater-bearing unit must meet at least one of the following conditions:
    (A) any groundwater-bearing unit within 1/2 mile of an existing well used to supply drinking water to a public water system as defined in §290.38 of this title (relating to Definitions), as amended, which can contribute COCs to the groundwater production zone of such public water supply well based on the chemical properties of the COCs, the hydrogeology, and the construction of the well;
    (B) a groundwater-bearing unit which is the only reliable source of water (i.e., a connection to a public water system is not currently available and will not be provided to the affected property as part of the RAP) not more than 800 feet below the land surface that is capable of producing groundwater with a naturally occurring total dissolved solids content of less than 1,000 milligrams per liter (mg/l) and at a sustainable rate greater than 5,000 gallons per day to a well with a four inch diameter casing or an equivalent sustainable rate in gallons per day to a well with a smaller or larger diameter casing; or
    (C) groundwater-bearing unit capable of yielding groundwater with less than or equal to a naturally occurring total dissolved solids content of 3,000 mg/l and at a sustainable rate greater than or equal to 144,000 gallons per day to a well with a 12 inch diameter casing or an equivalent sustainable rate in gallons per day to a well with a smaller or larger diameter casing, and the natural quality of that groundwater meets all primary drinking water standards as defined in 40 Code of Federal Regulations Part 141, as amended.
  (2) Class 2 groundwater resource. Class 2 groundwater resources include:
    (A) any groundwater-bearing unit which is a groundwater production zone for an existing well located within 1/2 mile of the affected property and which is used to supply groundwater for human consumption, agricultural purposes or any purpose which could result in exposure to human or ecological receptors; or
    (B) any groundwater-bearing unit which is capable of producing waters with a naturally occurring total dissolved solids content of less than 10,000 mg/l and at a sustainable rate greater than 150 gallons per day to a well with a four inch diameter casing or an equivalent sustainable rate in gallons per day to a well with a smaller or larger diameter casing.
  (3) Class 3 groundwater resource. Class 3 groundwater resources include any groundwater-bearing unit which produces water with a naturally occurring total dissolved solids content of greater than 10,000 mg/l or at a sustainable rate less than 150 gallons per day to a well with a four inch diameter casing or an equivalent sustainable rate in gallons per day to a well with a smaller or larger diameter casing.

Source Note: The provisions of this §350.52 adopted to be effective September 23, 1999, 24 TexReg 7436