Risk-Based Regulation of Oil and Gas NORM Waste Management Alternatives

1. Risk-Based Regulation of Oil and Gas NORM Waste Management Alternatives K.P. Smith, J.J. Arnish, G.P. Williams, D.L. Blunt, and H.I. Avci Environmental Assessment Division Argonne National Laboratory

2. How Has the NORM Issue Evolved in the U.S.? • Industry was aware of NORM in the U.S. as early as the 1930s. • Concern about the potential health risk did not develop until the early 1980s. • Regulatory controls were first established around 1984 and enacted by individual states. • Regulations were intended to reduce health risks associated with NORM, although without detailed risk assessments. • Subsequently, the results of waste analyses and risk assessments were incorporated into state regulations.

3. How is NORM Regulated in the U.S.? • At the state level only • Eleven states currently have specific NORM rules – five of these states have significant levels of oil and gas activity • Regulations establish • Exemption levels, • Management requirements, and • Disposal requirements • Variability exists among the state regulations

4. Exemption Levels For Loose Wastes and Soils Have “Evolved” In Some States • Initially, NORM exemption levels were derived from preexisting standards. • e.g., the USEPA standards for uranium and thorium mill tailing sites • Known as the “5/15 rule.” • 5 pCi/g (0.185 Bq/g) in the top 15 in. of soil • 15 pCi/g (0.56 Bq/g) in subsequent 15 in.-thick layers of soil • This standard may be overly restrictive (and expensive) for petroleum industry NORM wastes. • Several states have adopted 30 pCi/g (1.1 Bq/g) for wastes that have a low radon emanation rate.

5. NORM Regulations Have Limited the Number of Approved Disposal Options • Initially, states allowed a limited set of disposal options: • Land disposal facilities licensed for radioactive wastes • Plugged and abandoned wells • Other methods to be approved on a case-by-case basis • Limited disposal options translate into increased costs. • This is a reasonable outcome, as long as the potential risk warrants the extra costs. • Over time, additional disposal options have been approved: • Underground injection • Land disposal facilities licensed for nonhazardous wastes • Landspreading

6. Environmental Pathway Exposure Pathway Dose or Cancer Risk Source On-Site Direct Exposure External Radiation On-Site Air Concentration Dust/ H-3 Radon Inhalation Plant Foods Effective Dose Equivalent/ Excess Cancer Risk to an Exposed Individual On-Site Water Contamination Livestock Meat Milk Ingestion Aquatic Foods On-Site Soil Contamination Pathway Analysis Supports Establishment of Risk-Based Disposal Regulations

7. Underground Injection Analysis • Exposure pathway of concern: consumption of contaminated groundwater • Assumed worst-case scenario • Casing failure during injection in the shallow aquifer • NORM dissolved instantaneously • Conservative values used for groundwater gradient, hydraulic conductivity, and porosity • Closest receptor 0.3 km downstream • Both generic and site-specific situations have been modeled • Generic case: 100,000 bbl of waste containing 74 Bq/g of Ra-226

8. Estimated Doses for Underground Injection Present Negligible Risk These estimates are well below the ICRP-recommended dose limit of 1 mSv/yr from all man-made sources.

9. Case study based on municipal landfill in Michigan • Landfill design and operation • Institutional controls • Local population density • Subsurface conditions Disposal in Nonhazardous Landfills • Case study evaluated disposal of • 2,000 m3 of bulk waste containing 50 pCi/g of radium • 20 m3 of bulk waste, average concentration of 260 pCi/g of Pb-210

10. A Variety of Receptors and Pathways Were Modeled for Landfill Disposal • Operational Phase Receptors • Driver • Waste placement operator • Leachate worker • Off-site residents • Future Use Receptors • On-site resident • On-site industrial worker • Recreational visitor • Off-site resident

11. Estimated Doses for Landfill Disposal Present Negligible Risk • Provided that: • Landfill controls were maintained • Wastes were more than 3.3 m deep

12. Landspreading Disposal • Evaluated potential doses for a variety of receptors and pathways of concern • Assumed reasonable yet conservative parameters defining the landspreading operations • 2-acre (0.8-ha) tract of land • 0.2 m-thick contaminated zone • Calculated doses on a per unit basis

13. Estimated Doses Indicate Landspreading May Result in Unacceptably High Doses

14. Summary Remarks • Disposal alternatives that provide a high degree of isolation of the wastes (e.g., landfill disposal and underground injection) present acceptably low levels of risk to workers and the public, provided certain conditions are maintained. • Site-specific analyses are required to fully assess the potential risks and to ensure that adequate controls are in place. • NORM regulatory schemes should pursue the development of risk-based exemption levels and disposal regulations to ensure adequate protection of human health at the lowest possible economic impact.