Connecticut Department of Energy & Environmental Protection

Technical Impracticability Variance

A Technical Impracticability (TI) Variance is a remedial option provided under Section 22a-133k-3(e) of the Connecticut Remediation Standard Regulations (RSRs) that can be granted by the Commissioner to manage risks to human health and the environment in situations where there is no readily available technology to complete remediation and achieve compliance with the applicable groundwater criteria within a reasonable timeframe.

This option allows releases that have chronically impacted groundwater to achieve compliance with the GWPC and/or SWPC by exempting a specific geographic area (the TI Zone) from groundwater criteria while establishing long-term obligations ensuring the remedy protects human health and the environment in the following circumstances:

  • Residual source - groundwater impacts resulting from NAPL that cannot be effectively removed or degraded, typically DNAPL
  • Persistent plume - steady state or slowly diminishing plume where the source area has been remediated but the groundwater concentrations will not reduce to GWPC and SWPC within a reasonable timeframe due to low groundwater velocity or other geologic conditions

TI Variance Process


DEEP strongly recommends discussing any potential TI variance request with the DEEP district supervisor  and any Remediation Division staff that may have been involved with the release prior to submitting a TI variance request.  Please review pertinent RSR definitions prior to preparing to meet with DEEP.  Characterization  of the release and source area, demonstration that the source area has been remediated, and demonstration that the groundwater plume is either in a diminishing or steady state is required to move forward with a TI variance request.  When requesting an initial meeting, please provide tables summarizing the groundwater data and maps depicting AOCs, remediation areas, extent of NAPL, extent of plume, and cross sections. 
 
TI Variance requests that are submitted for DEEP review and approval must have the Electronic Document Transmittal Form as the cover page and be uploaded into the Connecticut Secure File Transfer (SFT) website.There is a two-step formal approval process for TI variances. The first step is the approval of eligibility resulting in the Commissioner indicating either:
  • the plume does not qualify for a TI variance, or
  • the plume does qualify for a TI variance with a request for additional information to be submitted within 120 days.

Approval of Eligibility (First Step)

Information Required to demonstrate that the groundwater plume meets the eligibility requirements for a TI variance includes:

  1. Substance(s) and concentration(s) in the groundwater plume
  2. Map showing the 3-dimensional extent of the groundwater plume that exceeds or could be expected to exceed GWPC and/or SWPC
  3. Demonstration of compliance with applicable soil criteria or if soil remediation is technically impracticable, that the polluted soil is not contributing to the groundwater plume
  4. Description of all actions taken to remediate the source and groundwater plume and the resulting analytical results
  5. Feasibility study demonstrating that achieving compliance with applicable groundwater criteria in a reasonable timeframe is technically impracticable
  6. Demonstration that the groundwater plume is in steady or diminishing state (or is hydraulically controlled)
  7. Map of the proposed TI zone including current and potential future withdrawals and a demonstration that withdrawals will not adversely affect plume migration or protection of human health and the environment
  8. Evaluation of current and potential future risks to human health and the environment if TI variance is granted and a contingency plan to eliminate or minimize any risks
  9. Plan for long-term monitoring, operation, maintenance, and reporting to demonstrate:
    • the plume is not increasing in size or concentration
    • no changes to the risk assumptions
    • no unacceptable risks occurring or contingency plan implemented
    • any controls are working and remain effective
  10. Type and amount of financial assurance to cover the costs of the long-term obligations.

Approval of Final TI Variance (Second Step)

The second step is the final approval of the TI variance request and results in written correspondence from the commissioner either approving or denying the TI variance request. The following information must be submitted within 120 days after the approval of eligibility (first step):
 
  1. Proof that public notice  of the proposed use of a TI variance was completed
  2. Certification that written notice of the extent of the groundwater plume that is proposed to remain was provided to each owner of property within the TI zone and the local Health Director
  3. If an ELUR is required, proof of acknowledgement and consent of each owner within the TI zone
  4. Demonstration that financial assurance has been obtained
  5. Demonstration that the ELUR or other permanent control measure is in place. Other permanent control measures may include a Stewardship Permit, Town ordinance, or designated design districts. The ELUR or other permanent control shall:
    • Require compliance with the plan and measures in the contingency plan and long-term monitoring, operation, maintenance, and reporting
    • Include any additional conditions required by the commissioner
    • Prepare five-year reviews to demonstrate effectiveness of the TI variance
    • If the variance is for GWPC, prohibit the use of groundwater for drinking and prohibit the withdrawal of groundwater
 
Content last updated October 21, 2025