(a) The area of review is the area surrounding an injection well or a group of injection wells, for which the permit application must detail the information required in Subchapter G of this chapter (relating to Consideration Prior to Permit Issuance).      
        (1) The area of review for Class I wells, except those wells authorized to inject only nonhazardous desalination concentrate or nonhazardous drinking water treatment residuals, is an area determined by a radius of 2 1/2 miles from the proposed or existing wellbore, or the area within the cone of influence, whichever is greater.       
        (2) The area of review for those Class I wells authorized to inject only nonhazardous desalination concentrate or nonhazardous drinking water treatment residuals, is an area determined by a radius of 1/4 mile from the proposed or existing wellbore, or the area within the cone of influence, whichever is greater. Notwithstanding subsection (c) of this section, if the area of review is determined by a mathematical model pursuant to subsection (b) of this section, the permissible radius is the result of such calculation even if it is less than 1/4 mile.       
        (3) The area of review for salt dome cavern disposal wells and associated caverns, is the sum of the two following areas:                  (A) an area determined by a radius of 2 1/2 miles from the proposed or existing wellbore; and                   (B) the greatest horizontal plane cross-sectional area of the salt dome between land surface and a depth of 1,000 feet below the projected floor of the proposed or existing salt dome cavern.         
        (4) The area of review for Class III wells, is the project area plus a circumscribing area, a minimum of 1/4 mile, the width of which is the lateral distance from the perimeter of the project area, in which the pressures in the injection zone may cause the migration of the injection and/or formation fluid into a Underground Sources of Drinking Water.       
        (5) The area of review for Class V wells is an area determined by a radius of at least 1/4 mile from the proposed or existing wellbore.       
      (b) The computation of the cone of influence may be based upon the parameters listed in the figure in this subsection and should be calculated for an injection time period equal to the expected life of the injection well or pattern. The following modified Theis equation illustrates one form which the mathematical model may take:      
        Attached Graphic       
      (c) After an appropriate review, the commission may modify the area of review. In no event shall the boundary of an area of review be less than 2 1/2 miles for Class I wells, except those wells authorized to inject only nonhazardous desalination concentrate or nonhazardous drinking water treatment residuals, or 1/4 mile for Class I wells authorized to inject only nonhazardous desalination concentrate or nonhazardous drinking water treatment residuals, or 1/4 mile from any other injection well covered by the appropriate authorization. The following factors are to be included in the review:      
        (1) Chemistry of injection and formation fluids;       
        (2) Hydrogeology;       
        (3) Population and its dependence on ground water use; and       
        (4) Historical practices in the area.       
      (d) The executive director may require an owner or operator of an existing injection well to submit any reasonably available information regarding the area of review, if the information would aid a review for the prevention or correction of freshwater pollution.     
     Source Note:        The provisions of this §331.42 adopted to be effective May 13, 1986, 11 TexReg 1982; amended to be effective July 5, 1989, 14 TexReg 3047; amended to be effective June 22, 1992, 17 TexReg 4097; amended to be effective April 28, 1997, 22 TexReg 3526; amended to be effective November 23, 2000, 25 TexReg 11433; amended to be effective July 10, 2008, 33 TexReg 5342; amended to be effective August 16, 2012, 37 TexReg 6078