State regulations must insist on a reasonably conservative gas composition exposure limit when using a gas dispersion model which does not take into account such mists and their outgassing. This can be done and we anticipate the results will be adequate to cover the actual situations that arise.
There are no atmospheric dispersion models that include the dispersion of a mist together with outgassing of H2S from solution. Therefore, selection of a pure gas dispersion model for the purpose of estimating health hazard risks appears to be necessary until more complete and reliable models become available.
Recommendation:
1. Assessment of locations for wells, lines and facilities should take into consideration general atmospheric conditions, topography of the land forms, as lakes, rivers, and valleys to the extent possible. One of the better EPA-sanctioned models should be utilized for the gas dispersion analyses. That would assure indirect professional oversight of the modeling process by virtue of national exposure of these models in the professional engineering community and peer review arising out of developmental research programs.
2. Funds for the study, including site inspection, site measurements, site assessment, preparation of input data, computational runs, and the presentation of the results would be paid for by the applicant for the permit. If this function is conducted under contract with a private firm, computations still should be made utilizing a publicly available, EPA-sanctioned dispersion model with a firm certified in competency in the use of the program. In any event, DEQ is responsible for site evaluation.
3. The site evaluation, the input data and output results for the atmospheric dispersion analysis, together with any further analyses of those data are to be placed in the public record for that permit. Those data will not be subject to any confidentiality period.
4. Whenever and where ever dispersion calculations, as modeled above, potentially place the public at risk of exposure above the 0.1 ppm public health exposure limit, the State's only legitimate role will be to unequivocally deny the permit and thereby protect public health, safety and welfare.
It is further the intention of this proposal to have in the public record the input data and the results of the H2S exposure computations made for each permitting situation: Local zoning bodies are acutely aware of the idiosyncratic water tables and land forms within their own communities. State staffs are limited.
Recommendation:
1. Each permit situation dealing with wells or facilities in a reef known to potentially contain dangerous levels of H2S should require a Notice of the Intention to Permit issued to the relevant local governments.
2. A45-day grace period to enable the public to respond, including the option of a public hearing process before a permit is issued and before any industry activities are commenced.
3. All non-conforming currently producing wells remain subject to existing law whereby local governments can deal with any health and safety issues that may be pertinent.
4. Shut in, or temporarily abandoned wells that do not meet the new public health exposure limit that we have proposed must be permanently plugged.
5. In view of the fact that those wells constitute public health hazards, the DEQ must take extraordinary measures to assure that such hazards are not realized, including advance notice of especially hazardous activities and other such preventive measures.
