SECTION 1 INTRODUCTION
The Nebraska Department of Environmental Quality (hereafter referred to as Department or NDEQ) developed this guidance in response to concerns regarding potential exposure risks from the remediation of petroleum contaminated soil and ground water through the use of air strippers (AS) and/or soil vapor extraction (SVE For the purposes of this protocol, the term SVE includes any remedial technology (e.g., bioventing, mechanical) that extracts petroleum vapors from the subsurface and emits them to the ambient air.) systems. It is applicable to any petroleum release remediation site, including underground storage tank (UST), aboveground storage tank (AST), pipeline, and surface spill contamination sites. Unless approved by the Department, this guidance is not to be used to assess exposure risks at hazardous substance/waste remediation sites (e.g., CERCLA, RCRA, etc.). In addition, it must not be used to evaluate risks for routine emissions associated with stationary sources (e.g., factories, industries, etc.).
Emergency situations, as declared by the Department Director, are not subject to this guidance until the emergency condition has been mitigated.
This document is guidance only and should not be construed as being regulation. For those areas of this guidance document that are required by statute or regulation (i.e., the Petroleum Products and Hazardous Substances Storage and Handling Act 81-15,124(2), Title 126 – Rules and Regulations Pertaining To The Management of Wastes, and NDEQ Title 129 - Nebraska Air Quality Regulations), the document language will indicate that the actions must be conducted. For those areas that are recommended, the document language will indicate that the actions are “recommended” or “should” be conducted. For clarification purposes, the emission assessments, both permitting and risk, must be completed. The manner in which they are completed is left to the discretion of the responsible party (RP) or their representative, and in the case of the Pay for Performance (PFP) process, to the discretion of the PFP contractor.
The AS portion of this document was developed in accordance with EPA document “AIR/SUPERFUND TECHNICAL GUIDANCE STUDY SERIES: Estimation of Air Impacts for Air Stripping of Contaminated Water” (EPA-450/1-91-02). The Department’s Air Quality Construction Permitting Team and Petroleum Remediation (PR) Section developed the SVE portion of this document.
Regulatory emission rates for hazardous air pollutants (HAPs) (Appendix C) are defined in NDEQ Title 129. Construction and Operation Permit information and calculation methods for HAPs are described in Section 2 of this document (process summarized in Appendix A). If a petroleum remedial system (i.e., AS, SVE, combined AS/SVE) is designed, operated, and modified as described immediately below, it is approved and will not require a permit.
- Design and operate the system(s) in such a manner as not to exceed contaminant concentration levels that would necessitate the need for a construction and/or operation permit (see Section 2B).
- Collect samples in the time periods established in the appropriate subsections of Data Collection and Sample Analysis Procedures (Section 2C) utilizing the identified analysis methods.
- Submit all air emission sampling data in accordance with Section 4, Reporting Procedures. For remediation projects conducted under the PFP Process, submit all air emission sampling data as established in the Department’s contract.
For carcinogenic volatile organic compounds (VOCs) only, an air emission exposure risk to the public must be calculated based upon a 1x10-6cancer risk (Section 3). If the emissions pose a cancer risk of 1x10-6 or less, then the system is approved for purposes of cancer risk (process summarized in Appendix A). If individual or combined HAPs and/or the cancer risk are greater than 1x10-6, then it must be reported to the NDEQ PR Section project manager, the remedial system must be redesigned, and best engineering practices (i.e., emissions control/treatment or system design modifications) are used to ensure that the cancer risk is not exceeded. For sites utilizing both AS and SVE systems, or more than one AS or SVE system, the total cancer risk is additive. That is, the cancer risk for each system must be determined individually, then summed, and averaged for all sampling events. If the cumulative risk is greater than 1x10-6, then measures must be taken as described above. If a petroleum remedial system (i.e., AS, SVE, combined AS/SVE) is designed, operated, and modified as described immediately below, it is approved.
- Design and operate the system(s) in such a manner that total VOC emissions do not exceed a cancer risk of 1x10-6 (see Section 3).
- Collect samples in the time periods established in the appropriate subsections of Data Collection and Sample Analysis Procedures (Section 3B) utilizing the identified analysis methods.
- Submit all air emission sampling data in accordance with Section 4, Reporting Procedures. For remediation projects conducted under the Pay For Performance (PFP) Program, submit all air emission sampling data as established in the Department’s contract.
Remedial actions taken in response to cleanup of petroleum releases from aboveground and underground storage tanks are eligible for reimbursement consideration under NDEQ Title 200 – Rules and Regulations for Petroleum Release Remedial Action Reimbursement Fund. Both the Department’s Air Quality and Water Quality Divisions consider the guidance and reporting procedures outlined herein as approved activities. If the assessment is completed in accordance with this approved guidance, reasonable costs associated with such actions are eligible for Title 200 reimbursement consideration.
Implementation of a remedial system without an AS or SVE assessment or with an assessment not first approved by the Department’s Petroleum Remediation Section (excluding those constructed under the Pay-For-Performance process) may result in reimbursement reduction of up to 100 per cent. Furthermore, construction and operation of a remedial system exceeding permit threshold levels established in Title 129 – Nebraska Air Quality Regulations is subject to enforcement and possible penalties by the Department’s Air Quality Division, including those systems constructed and operated under the Pay-For-Performance Process.
Utilizing the standard guidance and forms provided herein reduces reviewing time for NDEQ personnel. Should the RP or their consultant wish to propose alternative methodologies to evaluate air emissions, it must be done by submitting the proposal, in detail and in writing, for review to the PR Section as part of the Remedial Action Plan (RAP) for the site. At a minimum, it must be justified that any emission alternative methodology will provide better data than the methodologies provided and, at the same time, be of cost benefit. The Department will review alternative proposals on a case-by-case basis.