Aquifer Exemption Review

Information for Permitting Wells applicable for Aquifer Exemption

The checklist below outlines the information required for injection/disposal well applications that undergo an Aquifer Exemption review. Applicants are encouraged to submit any additional information that will assist aquifer exemption review.

Aquifer Exemption EPA Checklist for Operators

An aquifer or a portion thereof which meets the criteria for an "underground source of drinking water" in 40 CFR § 146.3 may be determined to be an "exempted aquifer". Class II wells must meet the criteria under 146.4(a) and criteria specified by least one of the following sections: 146.4(b)(1), 146.4(b)(2), 146.4(b)(3), 146.4(b)(4), or 146.4(c).

Demonstrate the following:

1. Location of proposed aquifer exemption
   • Township, Section, Range, Quarter Section or other method used to identify the area
   • Latitude and longitude
   • Distance to the nearest city/town:
   • Name of aquifer or portion of aquifer to be exempted:
   • Areal extent of the area proposed for exemption:
   • Depth and thickness of the aquifer:
   • TDS content of the aquifer, including the TDS at the top and bottom of the proposed zone to be exempted, and the locations and depths of all fluid samples taken.
2. Must meet the criterion in §146.4(a): The proposed aquifer or portion of the aquifer for which the exemption is requested is not currently used as a drinking water source.
   
   • Are there any public or private drinking water wells within and nearby the proposed well (Minimum review area of 5 miles) If yes, list all those wells:
   • Water well table: Table of all inventoried water wells showing: Well Name/#, Owner, (Private/Public), Contact information, Purpose of well (Public Water Supply, Domestic, Irrigation, Livestock, etc.), depth of source water, name of aquifer, well completion data, age of well (if known), and the primary source of well data (Applicant/State/EPA).
   • Maps: For all water wells that are screened in the proposed injection interval
     
     • Pertinent map(s) visually showing the areal extent of exemption boundary, depth and thickness of the aquifer proposed for exemption, all known subsurface structures such as faults affecting the aquifer, and each of the inventoried water well locations by well # or owner name.
     • Map showing the areal extent of exemption boundary, all domestic water wells considered potentially down gradient of the exemption and hydraulically connected to the exemption. If wells are deemed horizontally and/or vertically isolated from the exemption, this should be foot noted on the Table as well. Use arrow(s) to indicate the direction and speed of ground water in the aquifer proposed for exemption.
3. The proposed aquifer or portion of the aquifer for which the exemption is requested meets one of the following criteria:
   
   • Demonstration that the aquifer or portion thereof is mineral, hydrocarbon or geothermal energy producing per 146.4(b)(1)
     • If the proposed exemption is to allow a Class II enhanced oil recovery well operation in a field or project containing aquifers from which hydrocarbons were previously produced, commercial producibility shall be presumed by the Director upon a demonstration of historical production having occurred in the project area or field. It may be necessary to slightly expand an existing Class II operation to recover hydrocarbons and an aquifer exemption for the expanded area may be needed. If the expanded exemption for the Class II EOR well is for a well field or project area where hydrocarbons were previously produced, commercial producibility would be presumed.
     • For new or existing Class II wells not located in a field or project containing aquifers from which hydrocarbons were previously produced, information such as logs, core data, formation description, formation depth, formation thickness and formation parameters such as permeability or porosity shall be considered by the Director, to the extent available.
     • Also, exemptions relating to new or existing Class II wells not located in a field or project containing aquifers from which hydrocarbons were previously produced should include the following types of information:
       
       • Production history of the well if it is a former production well which is being converted.
       • Description of any drill stem tests run on the horizon in question, including information on the amount of oil and water produced during the test.
       • Production history of other wells in the vicinity which produce from the horizon in question.
       • Description of the project, if it is an enhanced recovery operation including the number of wells and their location.
       • Provide a summary of logging indicating that commercially producible quantities of hydrocarbons are present.

• • Demonstration that the aquifer or portion thereof is situated at a depth or location which makes recovery of water for drinking water purposes economically or technologically impractical per 146.4(b)(2)
    
    • List evidence in the application showing how this demonstration was made. EPA consideration of an aquifer exemption request under this provision would include information related to: The availability of less costly and more readily available alternative supplies, the adequacy of alternatives to meet present and future needs, and costs for treatment (including cost of disposal of treatment residuals) and or development associated with the use of the aquifer. The economic evaluation, submitted by the applicant, should consider the above factors, and these that follow:
      • Distance from the proposed exempted aquifer to public water supplies.
      • Current sources of water supply for potential users of the proposed exempted aquifer.
      • Availability, quantity, and quality of alternative water supply sources.
      • Analysis of future water supply needs within the general area.
      • Depth of proposed exempted aquifer.
      • Quality of the water in the proposed exempted aquifer.
  • Demonstration that the aquifer or portion thereof is too contaminated per 146.4(b)(3)
    • List evidence in the application showing that the area to be exempted is so contaminated that it would be economically or technologically impractical to render that water fit for human consumption.
  • Demonstration that the aquifer or portion thereof is located over a Class Ill well mining area subject to subsidence or catastrophic collapse per 146.4(b)(4)
    
    • List evidence in the application showing that the area to be exempted is located over a Class Ill well mining area subject to subsidence or catastrophic collapse.
  • Demonstration that the aquifer or portion thereof has TDS more than 3,000 and less than 10,000 mg/l and it is not reasonably expected to supply a public water system per 146.4(c)
    
    • Identify and discuss the information on which the determination that the TDS content of the ground water in the proposed exemption is more than 3,000 and less than 10,000 mg/I and the aquifer is not reasonably expected to supply a public water system.