## Wednesday April 17,

. 1985



# Part V



# Environmental Protection Agency

40 CFR 

## Part 61
National Emission Standards for Hazardous Air Pollutants; Standard for Radon-222 Emissions From Underground Uranium Mines; Final Rule

### 15386 Federal Register / Vol. 50, 

### No. 74 / 

### Wednesday. April 17. 1985 

## I Rules and Regulations

ENVIRONMENTAL PROTECTION AGENCY

40 CFR 

### Part 61

[AD-FRL-2814-7)

National Emission Standards for Hazardous Air Pollutants; Standard for Radon-222 Emissions from Underground Uranium Mines

AGENCY: Environmental Protection Agency (EPA).**~CTtON:** Final rule.

SUMMARY: The U

.S

. District Court for the Northern District of California has ordered EPA to promulgate a final standard for airborne emissions of radionuclides from underground uranium mines by April10. 1985

. or to find that radionuclides are clearly not a hazardous air pollutant. This final rule is designed to limit exposure ofthe public
to radon-222 emissions from underground uranium mines

. EFFECTIVE DATE : This final rule is effective onApril17. 1985. For existing
sources, the standards shall not apply until 90 days after the effective date.

ADDRESSES: The rulemaking record is contained in Docket No. A-79-11. This docket is available for public inspection between 8:00 a.m. and 4:00 p

.m., Monday through Friday, at EPA's Central Docket Section, WestTower Lobby. Gallery One. Waterside Mall. 401 M Str eet. SW., Washington. D.C. 20460. A reasonable fee may be charged for copying.

FOR FURTHER INFORMATION CONTACT: Paul 

### J. Magno. Environmental Standards Branch (ANR -460), Criteria and Standards Division. Office ofRadiation Programs. U.S. Environmental Protection Agency, Washington. D

.C. 20460, (703)**557~704.** SUPPLEMENTARY INFORMAnON:

I. Supporting Documents II. History of Uranium Mine Standard Development

On April 6. 1983. the Agency announced in the Federal Register a proposed standard to limit radon-222 emissions from underground uranium mines (48 FR 15076, Aprils, 1983). This proposed standard was withdrawn by the Administrator in October 1984 on the basis that it did not meet the legal requirements of section 112 of the Clean Air Act (49 FR 43906, October 31. 1984). The Agency has also received additional technical information that suggested that bulkheads and other techniques to control radon-222 emissions may be feasible. The withdrawal action was taken in response to an orderby the U

.S. District Court for the Northern District of California compelling EPA. by October 23, 1984

, to promulgate standards or make a finding that radionuclides are not a hazardous air pollutant within the context of section 112 of the Clean Air Act.

On December 11, 1984, the Court found the Administrator and t

. he Agency in contempt of its previous order and directed the following remedial actions:

1. (a) Issue within 30 days of the date of the order final radionuclide emission standards for Department ofEnergy (DOE) facilities, Nuclear Regulatory Commission (NRC)-licensed and nonDOE Federal facilities. and elemental phosphorous plants, and

(b) Issue within 120 days of the date of the order final radionuclide emission standards for underground uranium mines; or

2. Make a finding based on the information presented at hearings during the rulemaking. that radionuclides are clear ly not a hazardous air pollutant.

A final Background Information Document has been prepared and single copies may be obtained by writing the Program Management Office. Office of Radiation Programs (ANR-458), U.S. Environmental Protection Agency. Washington. D.C. 20460, or by calling {703) 5S7-9351. Please refer to "Background Information Document: The Agency promulgated final standards for DOE facilities, NRClicensed and non-DOE Federal facilities, and elemental phosphorous plants on January 17. 1985 (SO CFR S190lFebruary 6

. 1985). although it is noted that the Agency intends to pursue its pending appeal of this portion of the District Court's order. A complete history of the
events leading to this action is contained in the Federal Register notice " announcing the final standards.

Standard for Radon-222 Emissions to Air from Underground Uranium Mines." This document contains a descri ption of the uranium mining industry. proj.ected
exposures and risks to nearby individuals and to the general population

. and descriptions ofradon222 control methods. On February 21, 1985, EPA published in the Federal Register a proposed work practice standard to limit radon

-222 emissions from underground uranium mines (50 FR 7280, February 21. 1985)

. The proposed work practice standard required bulkheading abandoned and temporarily abandoned mine areas to reduce the amount ofradon-222 emitted
to the above ground air from the mines. Following publication ofthe proposed standard. EPA conducted a pbblic hearing in Albuquerque. New Mexico.

on February 27 and 28, 1985. The public record was held open until Marc h 26. 1985. to allow for written comments to be received, however. EPA asked that
comments be submitted as soon as possible to allow t he Agency maximum time to consider them. A significant number of comments were received by the Agency on the last day of the public
comment period. The short time between the submission of all the public
comments and the Court deadline for promulgating the rule allowed the Agency a limited opportunity to respond
to all**~f** the comments. The Agency has generally reviewed all of the comments and is responding to the major issues and points in this notice

. The Agency did not receive any comments or information subsequent to the public hearing that warranted a dramatic alteration in its approach

. Changes made to the final rule in response to points raised in oral and written
comments are discussed in the following sections

. III. Summary ofthe Final Rule

This rule is desi gned to limit exposure ofthe public to radon-222 emissions from underground uranium mines. The final rule differs in a number of ways from the proposed rule because of changes the Agency has made in
response to public comments. This section provides an overview ofthe final rule: changes from the proposed rule are noted. The rationale for each of these changes is provided in the following sections of this notice

. Both the Federal Register**noti~e** describing the proposed rule (SO FR 7280) and the Background Information Document provide further information on those portions ofthe final rule that have not changed from proposal.

The final rule: (1) Applies to an owner or operator of

an active underground uranium mine which has mined or will mine over 100.000 tons of ore during the life of the mine. A mine which will have or has had an annual ore production rate greater than 10,000 tons must also comply with the standard. unless it can be demonstrated that the mine will not exceed a cumulative ore production of 100,000 tons. (The proposed standard did not include the exclusion for mines producing greater than 10

.000 tons of ore peryear. but with an expected cumulative ore production ofless than 100.000 tons.)

{2) Requires that an owner or operator of an underground uranium mine install and maintain bulkheads to isolate all abandoned and temporarily abandoned

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## I Rules and Regulations 

### 15387

areas ofthe mine

. If

### a negative pressure behind the bulkhead is necessary, then a maximum of20 

### percent ofthe total volume of air contained in the sealed

area may be exhausted per day. A mine

owner or operator may apply for an alternative standard, ifnecessary to protect miner health and safety

. (The proposed standard did not provide a mine owner or operator the opport unity
to seek an alternative standard based on miner health and safety.)

(3) Requires quarterly inspections of bulkheads and quarterly measurements ofthe air exhaust rate for those bulkheaded areas maintained under negative pressure. (The proposed standard required monthly bulkhead inspections and monthly measurements ofthe air exhaust rate.)

(4) Requires that any necessary repairs to bulkheads be made within ten days. (The proposed standard required that bulkhead repairs be made within three days.)

(5) Requires an annual certification of compliance with the standard. (The proposed standard required an annual report summarizing the number and volumes of abandoned and temporarily abandoned mine areas: the number of bulkheads maintained: and an estimate ofthe average amount of airin the bulkheaded areas which is exhausted per day

.)

In establishing its final standard for radon-222 emissions from underground uranium mines. EPA had to weigh protection ofthe public health with protection ofthe mine personnel. The Agency believes that this standard will
not significantly increase the radon decay product concentrations to which the underground miners are exposed

. EPA intends to work with the Mine Safety and Health Administration to

ensure that implementstion of this standard will not jeopardize miner health and safety

.

This final standard requires a work practice, i.e., bul.kheading, which is commonly used throughout the uranium mining industry to direct fresh air to the working areas ofthe mine. Howeve

. r, the application ofbulkheads to seal workedout areas for reducing radon-222 emissions from underground mines has
not been thoroughly tested. Because of the limited time allowed by the Court order, EPA was unable to completely evaluate bulkheading or other potentially applicable work practices. EPA intends, once this standard is promulgated, to begin long-term st udies.

as necessary. to evaluate the efficiency ofbulkheads and other techniques for decreasing radon-222 emissions from underground uranium mines. IV. Background Infonnation

A. Industry Description



### Uranium mining involves the handling oflarge quantities of ore containing uranium

-238 and its decay products. The concentrations ofthese radionuclides in

ore may be up to one thousand times greater than their concentration

.in other rocks and soils. Uranium miningis

. predominantly**c~rried** 

### out by**ei~her** 

### surface {open pit) orundergrouf1d mining methods, depending on the depth, ore grade, and thickness ofthe

ore deposit. Underground uraniJm · mines have generally accounted! for about thirty to forty percent ofthe uranium oxide production in the United States.

The underground uranium mining industry has undergone substf!ntial changes in recent years due to declining demand and competition from lbw-cost foreign sources. The total number of underground mil)es fell from a p 1 

### eak of 300 in 1980 to only six by March 1985. Currently, all underground uranium mining in the United States takes place· in the western United States.**ln general.**  

### the mines presently operating are located in relatively remote areas of New Mexico, Colorado. Utah, and Arizona. Further reduction in the number of operating mines is

### pected during 1985.

Production ofuranium oxide by underground mines peaked at 9jloo tons in.l980; the industry estimates that uranium oxide production in 1985 will be approximately 1300 tons. EPA estimates that. based on Department ofEnergy projections ofuranium oxide demand, the industry will produce close to 3100
tons ofuranium oxide in 1985. 'I;'he Agency has taken into account
, both its

own and industry projections ofuranium oxide production in assessing**~e** 

### risk associated with radon

-222 emisSions from underground uranium minbs.

B

. Radionuclide Emissionsfron,l Underground Uranium Mines



### Radon-222 is the most significant radionuclide emitted to the above ground air from underground uranium

. mining activities. Radon

-222 is released from underground mines in relatively high concentrations through mipe ventilation systems

. Results of
measurement studies made at 27 

### large underground uranium mines

### d~ng 1978-1979 showed thatradon-222 emissions to airfrom individual mines ranged from 200 to 30,000 curies per year (Ci/y) with an average of5600 Ci/y

. These mines accounted for approximately 65 percent ofthe uranium

·oxide produced by all undergrqund mines in 1978

. Based on these measurement results, the total radon-222 emissions from all underground uranium 

### mines in 1978 were about 240,000 curies. EPA estimates emissions ofradon-222 will be about 80,000 CUDes in 1985, based on DOE projections ofuranium oxide demand. Using industry projections ofuranium oxide production. emissions ofradon

-222 will be about 35,000 curies in 1985.

It is important to note that the rate of radon-222 emissions from underground uranium mines is highly variable, depending upon a nwnber of interrelated factors, including mine ventilation rates, ore grade, exposed surface area, mining practices, and geologic formatio!UI. In addition, these mines can differ significantly in their configuration. The wide diversity among mines makes it difficult to predict emission rates ofthe effectiveness of emission reduction practices at any given mine.



### C. Estimates of Exposure andRisk



### The risk associated with emissions from underground uranium mines is primarily due to the short half

- life decay products ofradon-222. Radon-222 · decays into a series of short-lined radionuclides. These decay products readily attach to dust particles that may become lodged in the lung when inhaled. thus irradiating the surrounding cells.

Individuals living near an underground uranium mine canbe exposed to increased levels ofradon decay products of a result ofradon-222 being released ft·om the mine ventilation shafts. Radon-222 contained in the outside atmosphere enters homes and other
structures built nearthe mine exhaust
vents through doors and windows, as well as other openings in the structure. The occupants ofthese structures may then be exposed to potentially harmful levels ofradon-222 decay products.

The increased lifetime risk offatal lung cancer to individuals living near large underground uranium mines from the mine emissions is estimated to range from about one in one thousand to one in one hundred. The potential exists for

an increased risk as great as one in ten in some situations, e.g, a person living very close to several horizontal mine
vents or in areas influenced by multiple mine emissions. EPA estimates the increase in the fatal cancer risk to the total population from radori

-222 · emissions from underground uranium mines to have been about one to four fatal cancer cases per year during the peak production period of 1978-1982. With the decrease in the number of operating underground uranium mines, the increased risk offatal cancer is

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expected to range from four-tenths to two fatal cancercases per year during the period 1983-1990. Based on industry production projections, the increased risk offatal cancer in 1985 is estimated
to range from three-tenths to six

-tenths of a fatal cancer case.

Exposure levels are derived from emission estimates, dispersion modelling, and population data

. For any given emission rate. dispersion models predict concentrations a t different distances from the emission source. By combining th

. ose estimated
concent rations with census data on population densities. the number of people exposed at different concentrations can be estimated. However, several factors suggest that actual exposure levels to nearby individuals will be lower than t hose estimated. In estimating exposure

. exposed individuals are assumed to be subjected to the emissions for 24 hours every day for 70 years (roughly a lifetime). This does not consider

, for instance. the fact that most people in their daily routines move in and out of the specific areas where the concentrations are the highest. In the

case ofunderground uranium mines, the average life of a mine ranges from 1()-20 years, although some mines have operated for almost thirty years.

Several commenters expressed

concern about the Agency's risk estimates and the need for

**r~gulalion** of this source category. Three specific points were addressed: (1) The risk from radon

-222 emissions from underground uranium mines is not of the magnitude

necessary to warrant regulation under section 112 ofthe Clean Air Act. therefore, the Agency should "delist" radionuclides from regulatory consideration under section 112; (2) little evidence exists to indicate health effects result below total exposure levels of one hundred working level months; and (3) the decline in the uranium mining industry significantly deflates t he already overestimated health risks presented by the Agency.

The Agency has considered t hese interrelated issues and has concluded that the "listing" ofradionuclides as a hazardous air pollutant within the
context of section 112 ofthe Clean Air Act was entirely appropriate

. Section 122 of the Clean Air Act requires the Administrator to review all available relevant information and determine whether emissions ofradioactive pollutants to the ambient air will <:ause,

orcontribute to, airpollution which may reasonably be anticipated to endanger public health

. Ifthe Administrator concludes that emissions of radionuclides meets this criterion

, he

must list and regulate radionuclides under section 108(a)(l), section 111(b)(1)(A), or, ifhe finds that radionuclide emissions cause. or contribute to, air pollution which may reasonably be anticipated to result in an increase in mortality or an increase in serious irreversible, orincapacitating reversible, illness

, section 112(b)(l)(A) of the Act, or take any combination of such actions

.

The Agency believes that emission of radionuclides from underground uranium mines meets the general criterion for an affirmative finding under section 122. Further, the Agency believes that emissions ofradionuclides from underground uranium mines meet the criterion for regulation under section 112

of the Act. Specifically, there is no doubt that radionuclides are carcinogenic, mutagenic. and teratogenic. This conclusion is based on extensive scientific evidence derived from studies ofboth human and animal populations. Underground uranium mines emit radon222 and its decay products in large quantities. Many studies in the United States and other countries ofminers exposed to radon-222 gas and its decay products have presented highly convincing evidence that exposure to these radionuclides causes or contributes to lung cancer.

Estimating the magnitude ofthe increased risk of developing lung cancer to individuals living near underground

uranium mines and to the general population living downwind ofthe mines is complicated and uncertain. Epidemiological data exist that demonstrate a relationship between cumulative exposure to radon-222 decay products and increased lung c;ancer risk. There is substantial evidence that relates cummulat ive exposure of greater than approximately one hundred

wor king level months (WLM) to an increased risk oflung cancer. While

some studies based onhuman data indicate that exposure to less than one hundred WLM increases the risk oflung

cancer. these data are less conclusive. There are considerable difficulties in demonstrating increased risk at a statistical confidence level of95 percent for exposure at relatively low concentrations ofradon-222 decay products because a very large study population is needed. It is often difficult
to identify appropriate study populations large enough to conduct such studies to examine risks at very low levels.

Cumulative exposure to a person living near an undergound uranium mine due to mine emissions is not likely to exceed twenty WLM overhis lifetime. (This assumes exposure to about 0.3 WLM per year for about 70 years

.) While this is considerably below cumulative exposures at which we have substantial human evidence relating to lung cancer, the Agency believes that such exposure is not below a threshold
at which no signficant health damage could occur. Radiation protection organizations, national authorities, and prestigious scientific committees worldwide use the assumption that there is no threshold below which
exposure to radiation does not pose

some risk to health

. For example, the National Academy of Sciences' Committee on Biological Effects of Ionizing Radiati{ln recommended that health risks from low level exposures to alpha radiation

, such as that produced by radon

-222 decay products. be · estimated by extrapolating risks from higher exposures using a linear nonthreshold model. Therefore, extrapolations from the available miner epidemiological data have been used by EPA to estimate risk at exposure levels caused by radon

-222 emissions from underground uranium mines

.

Section 112 requires not only a finding that the pollutant at issue is hazardous in the abstract, but also that it poses a · public health risk in its from as an air pollutant. By coupling information on radon-222 emissions form m ines, air transport models, and health risk models, the Agency estimates that the increased lifetime risk to individuals living near an underground uranium mine could be about one chance in one hundred ofincurring lung cancer because ofthe emissions. For perspective, the current average lifetime risk of developing lung cancer in the United States is about three in one hundred. Clearly. radon-222 emissions from underground uranium mines may significantly affect a nearby individual's lung cancer risk. In addition

, several fatal cancers peryear may result in the total population due to these em issions. depending on the quantity of ore production each year.

In making its health risk estimates, EPA evaluated the airpollution risk of radon-222 emissions from underground uranium mines based on the magnitude ofboth current and potential emissions,

on observed and estimated ambient radon-222 concentrations, on the proximity oflarge populations to emitting sources, on estimates ofhealth risk to exposed populations, and on considerations ofuncertainties

associated with risk estimates. The
assessments and the assumptions used
to estimate lifetime risks are described

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in more detail in the Background Information Document. In addition, a study conducted during the period 1976- 1980 by the New Mexico Environmental Improvement Division clearly demonstrated elevated concentrations ofradon-222 in air near underground uranium mines in the Ambrosia Lake

area ofNew Mexico.

The Agency believes that there is sufficient evidence to conclude that potential increases in the risk oflung

cancer to individuals and the general population due toradon-222 emissions from underground uranium mines may be anticipated to endanger public health and may be anticipated to result in an increase in mortality. Consequent ly, regulation ofthis source category under sections 122 and 112 is appropriate.

The Agency also believes that a standard limiting exposure ofthe public
toradc.m-222 emissions from underground uranium mines is warranted, despite the low number of operating mines. The Congress int ended in section 112 that EPA actby a date certain to protect the health ofcurrent and future generations from emissions of pollutants that it determined to be hazardous. This is still the Agency's responsibility even if. as some might argue, current production levels have reduced risk. Demand for uranium oxide may increase. In the peak production
years, the increase in an individuat's lifetime risk oflung cancer from radon

- 222 emissions from underground uranium mines may have been as high

as one in ten to those individuals exposed to mulitiple mine vents an.d increased population risk may have been as high as four fatal cancers per year. Without a standard such as this. risks to the public, both nationally and regionally, would increase 

### ifdemand and production of uranium oxide increases.

Section 122 ofthe Clear Air Act allows EPA to use section 108(a)(1) or section 11l(b){I)(A) in combination with section 112 ifthe Administrator determines it 

### to be suitable. At this time, the Agency has chosen to regulate radon-222 emissions from underground uranium mines only under section 112. Current information suggests that regulation under these other sect ions would not significantly improve control ofradon-222 emissions from underground uranium mines. Should

new information alter this conclusion, the Agency may reconsider its approach
to regulating underground uranium mines.

D. Control Technology



### Since radon-222 is a noble gas and the volume of air discharged through mine vents is very large, at present there is no practical method to remove radon-222 from the mine exhaust air. Application ofconventional methods to remove radon-222 from mine ventilation air at the volumes of air 

### which must be treated would require large, complex, unproven systems that woiJld 

### be extremely costly, i.e., adding at least $18 to $44 

### to the total
cost ofproducing a pound ofuranium oxide

. (Currently, the average cost to produce one pound ofuranium oxide from an underground mine is about $35.) 

### The industry now employs 

# anumber of practices to reduce radon decay product concentrations in the mine to meet occupational exposure standards established by the Mine Safety and Health Administration. These practices. which include bulkheading abdndoned

areas ofthe mine, have the effJct of reducing radon-222 emissions to the above ground air.

AtEPA's request, the U.S. Bureau of Mines evaluated the cost and effectiveness ofvarious work practices in reducing radon-222 emissions. The results ofthe study suggested that

. bulkheading could reduce emissions of radon-222 by about 10 to 60 percent. Based on the peak production year, the
amount ofpopulation risk reduction achieved could range from two-tenths to two fatal cancer cases per year. Estimates for 1983, the most recent year for which actual production**d~ta** 

### are available, range from**one-tent~** 

### to one fatal case per year. In 1985, based on Industry production projections, the
amount ofpopulation risk reduction is estimated to range from three· hundredths to three-tenths ofa fatal

cancercase per year. These**ar~** 

### only rough estimates based on installing bulkheads in a presently uncontrolled mine (i.e

., a mine with no bulkheads).

Information presented during the public comment pericd indicat' es that uncertainty exists as to the amount of radon-222 emission reduction achievable by bulkheading in existing mines. This is in part due to the**complexi~y** 

### in the configuratio* ofthese mines, past mining practices, and consideration ofminer health hnd safety. The extent to which arl:ditional bulkheads can be installed to furthc:- reduce radon

-222 emissions can only be determined on a case-by

-case basis.

Comments from the industrY supported EPA's conclusion tHat bulkheading is the only**practi~l** 

### work practice that could be used to reduce radon-222 emissions to the above ground air. Other methods, such as rock sealants andbackfilling•.may also reduce r!ldon-222 emission!!; however, they are not thought to be as cost· effective or practical

. as bulkheading. After considering all the available information on cont rol technologies. the Agency has concluded that bulkheading abandoned and temporarily abandoned mine areas to seal t he radon-222 underground is a practical method of reducing radon-222 emissions from the mines to the above ground air.

E. Bulkheading



### Bulkheads are air-restraining barriers used to direct air and prevent contamination or leakage of fresh air going to the active areas ofthe mine. This practice reduces the radon-222 and decay product concentrations in the active areas of the mine and also reduces the volumes of air needed to ventilate the mine. Bulkheading practices vary among mines: some mines make extensive use ofbulkheads, while others use few bulkheads.

A secondary benefit ofbulkheading inactive areas of a mine is that radon· 222 emanating from the rock surface will decay in the isolated area. Hence, this technique can also reduce radon-222 emissions to the above ground air. The
amount ofemission reduction achieved is dependent on the volume ofinactive

areas that are sealed with bulkheads and the amount ofair removed from these areas. ·

The radon-222 in the sealed area behind a bulkhead will build up to relatively high concentrations (i.e

.. tens of thousands ofpicocuries per liter), so it is necessary to prevent orminimize any leakage of air from behind the bulkhead into the working areas of the mine. Any such leakage could significantly increase

.the radon decay product concentration to which the miners are exposed. Therefore, it is often necessary to maintain a negative differential pressure behind the bulkhead to prevent leakage of contaminated air into the act ive mine airways. This negative pressure is achieved by bleeding (i.e., removing) air from behind the bulkhead into an exhaust airway. For bulkheads to be effective In reducing radon-222 emissions to above ground air, however, the amount ofair bleed necessary to maintain an adequate pressure differential across the bulkhead must be minimized

. The smaller the air bleed, the

more radon-222 will decaybehind the bulkhead rather than being released above ground.

V. The Fin

. ol Standard

The complexity in the structure'of underground uranium mines, the uncertainties in the effectiveness ofinmine control techniques, and the Jack of suitable control technology to capture

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radon-222 being vented from the mines

cause the Agency to conclude that an emission standard is not feasible. The effectiveness oftechniques for radon222 emission reduction is not known. This means that predictable. hence measurable, steps toward compliance with a generic emission atandard can not be identified. In thia inatance, section 112(e)(1) ofthe Clean Air Act allows the Agency to prescribe a work practice or other type standard to control the pollutant. This standard, therefore, requires that bulkheading be used toreduce emissions ofradon-222 from the mines. A more thorough description ofthe individual components ofthe standard and the rationale follow&.

A. Applicability

The standard is applicable to an owner or operator of an active underground uranium mine which has mined or will mine over 100,000 tons of

ore during the life ofthe mine. Mines which have bad or

### will have an annual

ore production rate greater than 10,000 tona must also comply with the standard. unless it can be demonstrated that the mine will not exceed a cumulative ore production of 100.000 tons.

An evaluation ofradon-222 emissions from underground mines operating In 1978 as a function ofcumulative ore production showed that 188 mines or 75 percent of all the mines had a cumulative ore production ofless than 100.000 tons. The estimated radon-222 emission rate from each ofthese mines

waa lesa than 200 curies peryear, and as
a group they contributed only five percent of

**th~** total cunes emit ted by all underground uranium mines in 1978. Since theradon-222 emissions from underground uranium mines with cumulative ore productions ofless than 100.000 tons are amall, the Agency baa concluded that these mines need not be covered by the standard.

One commenter suggested that the Agency eliminate the 100,000 tons of cumulative ore production criterion;

another suggested increasing it to 500,000 tons. The Agency has decided to maintain the cutoff at 100,000 tons cumulative ore production in order to include older mines which are likely to have significant emissions ofradon-222 due to the large amount of surface area emanating this radionuclide. EPA chose the 100,000 tona cutoffbased on the results ofthe study discussed previously. Ninety-five percent of the radon·222 emissions from underground uranium mines In 1978 were from mines with a cumulative ore production of 100.000 tons orgreater

. The annual ore production value of 10.000 tons was selected to ensure that mines which are likely to exceed 100.000 tons ofcumulative ore production will be covered by the standard on the effective date ofthe standard or at the time a new mine begins production. Evidence exists which indicates that mines with an annual ore production
rate of 10.000 tons or greater are likely to mine 100,000 tons of ore during their lifetime. The standard allows a mine

owner or operator to demonstrate that the mine will not exceed 100,000 tons of cumulative pre production, and, thus,
not be subject to the atandard.

B

. Bulkheading Requirements

Comments generally agreed with the Agency's conclusion that bulkheading is

a practical method to reduce radion-222 emissions to the above ground air from underground uranium mines. One commenter suggested that backfilling abandoned areas with mill taili.ngs might also yield aome reduction in radon-222 emissions. Thia final rule. while prescribing bulkheading requirements, allows a mine owner or operator' the flexibility to use other methods ofradon-222 control. such as backfilling. upon approval by the Administrator.

The standard requires that an owner
or operator of anunderground uranium mine install and maintain reliable bulkheads to isolate all abandoned and temporarily abandoned areas ofthe mine. If a negative pressure behind the bulkhead is necessary, then a maximum of 20 percent ofthe total volume of air contained in the sealed area maybe exhausted per day

. Many commenters expressed concern about limiting the amount of air which can be drawn from behind a bulkhead to achieve a negative pressure. In some situations. this practice may result in an increase in radon-222 decay product concentrations in the working areas ofthe mine. In addition. it may be difficult or impractical to measure the amount of air removed from a bulkheaded area. Commenters requested that EPA eliminate thelimitation on the amount of air which can be drawn from behind a bulil!b!ad.

EPA does not intend to promulgate a standard which increases miner exposure to radon decay products. However, a limit on the rate ofremoval of air from behind a bulkhead is necessary to provide sufficient residence time for the radon-222 in the isolated area t"decay. A 20 percent per day value was selected as a balance between the need to minimize the rate of air removed from the isolated area and the need to maintain adequate negative pressure to prevent radon-222 from leaking into active mine airways and increasing the radon

-222 decay product exposure to the miners. Our analysis estimates that, when the exhaust rate is maintained at 20 percent
, approximately 50 percent oft he radon222 trapped behind the bulkhead will decay and thuo will not be vented to the above ground air. Reducing the air exhaust rate to 10 percent per day would result in a radon-222 reduction of approximately 65 percent. but we do not have enough information at the present time to know ifthis will provide adequate protection of the miners.

Industry representatives explained to EPA that the ventilation routes in many existing mines are designed so that air from active areas is exhausted through the inactive areas ofthe mine. As fresh air is brought into the mine

, care is taken to prevent its contamination with radon-222 decay pr oducts prior to its reaching the active work areas. Bulkheads are constructed primarily to

seal unused portions of the mine ad

jacent to the intake airways·to prevent fresh air from escaping or becoming contaminated. In current practice. the mined-out areas become exhaust airways as the mining process retreats towards intake airways. Therefore. a major portion ofthe minedout areas must be kept open to allow passage of air to the exhaust vents. In the case ofone mine. ninety-six percent ofthe mine is inactive areas which serve
as exhaust routes for contaminated air. Bulkheading is unlikely to be practical in these inactive areaa unless major changes are made in the ventilation schemes ofthe mines. such as constructing new ventilation shafts. In addition, entering these areas to construct bulkheads may jeopardize the health and safety ofthe miners because ofhigh concentrations ofradon-222 decay products and ground instability. Commenters requested that EPA exempt from the requirements ofthe standard inaccessible areas and those areas which serve as ventilation passageways.

After hearing the comments discussed above and reviewing the configurations of several existing mines, the Agency has decided to include a provision in the standard to allow mine owners or operators to apply for an alternative standard, ifnecessary

- to protect miner health and safety. By including this option, rather than simply eliminating the air exhaust rate limitation and exempting certain areas of

·a mine based

on their function

, the Agency hopes to 

### provide incentive to design new 

### mines in such a way as to limit radon-222 emissions to above ground air. Industry

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representatives acknowledged at the public hearing that a new mine could be designed to limit the number ofinactive

areas used as exhaust routes and to maximize the amount ofarea which could be bulkheaded

. C. Reporting andRecordkeeping



### The Agency received numerous comments on the reporting and recordkeeping requirements of the proposed rule. In 

### an effort to minimize the amount ofadditional time personnel
must spend in a mine to meet its standard, EPA has decreased the number and frequency orthe reporting and recordkeeping requirements imposed by the final rule. The revisions

are as follows:

(1) 

### Inspections The frequency of inspections ofbulkhead conditions and measurements ofthe air exhaust rete for those bulkheaded areas maintained under negative pressure has been reduced from monthly to quarterly. Records ofthese

_ inspections must be kept at the mine and be available for review byEPA.



### (2) Bulkheadrepairs The length of time allowed to make necessary repairs to bulkheads hasbeen lengthened from three days to ten days. This change ellows mine operators greater flexibility in managing their work force.

{3)Annual

### report The amount of information that is required to be submitted aMually to EPA 

### baa been reduced. A mine owner oroperatormust submit an aMual certification of compliance with the final rule. Records ofthe number and volumes of abandoned and temporarily abandoned

areas. the number ofbulkheads maintained, and an estimate ofthe average amount ofairin the bulkheaded

orcas which is exhausted per day must be kept at the mine. Annual submissiort ofthis Information was required In the proposed rule.


### D. Definitions



### Based on public comments. several definitions were modified in the final rule.

(1) The definitions of"abandoned mine area" and "temporarily abandoned mine area·• have been modified 

### to exempt not only those oreas which function as escapeways. but also areas formerly-uaeii as lunchrooms. shops, and transformer orpumping stations. These areas have been exempted because they are nonproduction areas which have low radon-222 emanation rates. In addition. the exemption for ventilation passageways 

### Is now limited
to ventilation passageways designed to minimize the distance to vents and no longer allows Iorge mined-out areas to function as ventilation passageways. Exempting these areas from the bulkheading requirements would limit the amount ofradon-222 emission reduction achieved by the standard. In 

### particular, the Agency wants to ensure that new mines are designed to avoid this practice

. .

(2) The definition of "active mine" has been modified to include only those mines in which ore or waste material

are currently removed by conventional methods. This change was made to exempt slope leaching which does not require workers to enter the mine, exceptinrare instances.

(3) 

### A definition of "work" has been added to clarify the intent of the standard. For the purposes of the standard, "work" means mining act ivity done in the usual and ordinary course of developing and operating an underground uranium mine.


### VI. 

### Effects ofthe Fi.aal Standard

Thedeadline imposed by the District Court requires the Agency topromulgate

a standard for underground uranium mines based only on the currently available technical information. An accurate estimate ofthe radon-222 emission reduction achieved by the standard cannot be made with existing Information. The bulkheading requirements ofthe rule are expected to result In 

### a decline ln individual and population risks as emissions ofradon222 

### are reduced. Though the maximum Individual risk in particularhae not been reduced to levels EPA bas selected in other standards. the very short time

.available for developing this rule. and the possibility that any reduction In risk

. to the general population might be · achievable only by increasing the risk to miners. make it impossible to impose further controls at this time. EPA 

### will continue to Investigate this m11tter to determine the possibility oftightening controls in the 

### futl11'1!. Since most mines already install bulkheads to reduce ventilation requirements, It 

### is not possible to estimate the incremental radon-222 emission reduction achieved by the standard. EPA intends to gather additional information on the extent and nature ofexisting bulkheading practices and the efficacy ofthe standards.

Further. the cost ofthe staqdard can only begenerally estimated. Because we do not know the extent ofpresent bulkheading practices orwhat additional bulkheading is practical, we cannot precisely estimate the coat to meet this standard. Limited modelling

analysis shows that the coat ofinstalling bulkheads ranges from about one to five cents perpound ofuranium oxide produced. Based on the peak production year. the total cost to the industry could range from $200,000 to $1.000

, 000 per year. Cost to the total industry in the first year is estimated to range from $30,000 

### to $150,000. 

### Even ifthese costs

are significantly Wlderestimated for

some mines. it is highly Wllikely that the cost ofthe standard would exceed one percent of the cost ofproducing uranium oxide.

EPA 

### intends to begin long-term studies. as necessary. to more thoroughly determine the efficiency and cost ofbulkheads and othertechniques for decreasing radon-222 emissions to the above ground airfrom underground uranium mines. Such a study would examine ways to reduce air emissions further without increasing potential exposure to miners. The results of a study may lead to some modification of the Agency's standard.


### VII. Miscellaneous

A. Docket



### The docket is an organized and complete file ofall information considered by EPA in the development ofthis standard. The docket allows interestedpersons to Identify and locate documents so they can effectively participate In the rulemaking process. It 

### also serves aa the record for judicial review. Transcripts ofthe hearings, all written statements. and otherrelevant documents are placed ln the docket and

are available for lnapection and copying during 

### normal working hours.


### B. GeneralProvisions

The general provisions of40 CFR 

### Part 61, subpartA apply to all sources regulated by this rule.


### C. 

### State Implementation and Enforcementof Emission Standards
D. Communications

Communications with the Administrator regarding the reporting and recordkeeping requirements ofthis rule. as well as requests for waivers, shall follow the provisions of 161.10, except as otherwise noted In 

### this rule.


### E. Executive Order 12291



### Under Executive Order 12291, issued February 17, 1981, EPA must Judge whether a rule Is a "inajorrule" and. therefore. requires that a Regulatory Impact Analysis be prepared. EPA has determined that this rule is not a major rule as defined In section 1(b) ofthe Executive Order because the aMual effect ofthe rule on the economy will be 

### less than $100 

### million. Also. it will 

### not

cause a major increase in costs orprices for any sector ofthe economy orfor any

### 15392 Federal Register 

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## I Rules and Regulations

geographic region. Further, it will not result in any significant adverse effects

on competition, employmeni. investment, productivity, innovation, or the ability ofUnited States enterprises
to compete with foreign enterprises in domestic or foreign markets. Under Executive Order 12291, this rule was submitted to the Office ofManagement !lnd Budget (OMB) for review. Any written comments from OMB to EPA, and responses to those comments, are included in the docket.

F. Paperwork ReductionAct

The information collection requirements contained in this rule have been approved by OMB under the provisions ofthe Paperwork Reduction Act of 1980, 44 U.S.C. 3501 

### et seq. and have been assigned OMB control number 2060-{)115.

G. Regulatory FlexibilityAnalysis

Section 603 of the Regulatory Flexibility Act, 5 U.S.C. 603, requ

. ires EPA to prepare and make available for
comment an "initial regulatory flexibility analysis" in connection with any rulemaking for which there is a statutory requirement that a general notice ofproposed rulemaking be published. The "initial regulatory analysis" describes the effect of the proposed rule on small business entities.

However, section 604(b) ofthe Regulatory Flexibility Act provides that section 603 "shall not apply to any proposed

. . . rule ifthe .head of the Agency certifies that the rule will not, if promulgated. have a significant economic impact on a substant ial number of small entities."

EPA believes this final rule will have little orno impact on small busi ness because the total costs associated with the standard will have relatively little impact on the total cost ofproducing uranium oxide. In addition. the standard will apply only to large, operating underground uranium mines.

For the preceding reasons, I certify that this rule; will not have significant economic impact on a substantial number of small entities.

H. JudicialReview

Judicial review ofthese standards is available only by filing a petition for review in the United StatesCourt of Appeals for the District of Columbia Circuit within 60 days of today's publication date

. Therequirements established in this notice may not be challenged later in civil orcriminal proceedings brought by EPA to enforce them. List of Subjects in40 CFR Part 61


### Air pollution control, Hazardous materials, Asbestos, Beryllium, Mercury, Vinyl chloride, Benzene, Arsenic. Radionuclides.

Dated: April10, 1985. Lee M. Thomas, Administrator.

Part 61 ofChapter 1 ofTitle 40 ofthe Code ofFederal Regulations is amended by adding the following Subpart B consisting of §§ 61.20 througll 61.28:

PART 61-(AMENDEDJ

SubPart 8-Natlonal Emlaalon Standardfor Radon-222 Emissions trom Underground Uranium Mines

Sec. 61.20 Applicability. 61.21 Definitions. 61.22 Standard. 61.23 Alternatives Standard. 61.24 Bulkhead Inspection and Testing. 61.25 Bulkhead Repair

. 61

.26 Recordkeeping. 61.27 Reporting Requirements.
61.28 Source Reporting and Waiver Request.

Authority: Sec. 112 and 301(a) Clean Air Act, as amended, 42 U.S

.C. 7412. 7601(a)

. Subpart B-NaUonal Em188lon Standard for Radon-222 E'ml88lona from Underground Uranium Mines

§ 61.20 Applicability.

The provisions ofthis subpart are applicable to an owner oro'*'rator of an active underground uraniumI mine which:

.

(a) Has miried or will mine over 100,000 tons of ore during**th~** life ofthe mine; or

(b) Has had or will have an annual ore production rate greater than 10,000 tons, unless it can be demonstrate; d that the mine will not exceed a total ore production of 100,000 tons during the life ofthe mine.

§ 61 .21 Deflnltlona.

AJj used in this subpart. all terms not defined here shall have the meaning given them in the Clean Air Act or in subpart A ofPart 61 and the following**tennt~** shall have the specific! meanings given below:

(a) "Abandoned area" means

# a deserted mine area in whichJ work has ceased and in which furtherrork is not intended. Areas which function as escapeway&, and areas form: erly-used aa lunchrooms, shops, and transfonner or pumping stations are not cortsidered abandoned areas: Except for designated ventilatjon passageways

### de~lgned to minimize the distance to verlts. worked·
out mine areas are considered abandoned areas for the purpose ofthis subpart.

(b) "Active mine" means an underground uranium mfne from which

ore or waste material is currently removed by conventional methods.

(c) "Area" means a man-made underground void from which ore or· waste has been removed.

(d) "Bulkhead:' means an airrestraining barrier constructed for longterm control ofradon-222 and radon-222 decay product levels in mine air.

(e) "Inactive mine" is a mine from which uranium ore has been previously removed but which is not an active mine

as of the effecUve date o!.lhe standard. Inactive mines which become active mines after the effective d&te uf the standard are considered new sources under the provisions of subparts A and B ofthis part.



### (0 "Modification" as applied to an active underground uranium mine

means any major change in the method of operation or mining procedure which will result in an increase in the amount ofradon-222 emitted to air. The normal development or operation of an active mine, even though it results in an increase in emissions, is not considered

a modification for the purposes of this subpart.

(g) "Temporarily abandoned area"

means a mine area in which further work is not intended for at least six months. Areas which function as escapeways. fonnerly-used lunchrooms, shops. and transformer orpumping stations are not considered abandoned

areas. Except for designated ventilation
passageways designed to minimize the distance to vents, worked·out mine

areas are considered temporarily abandoned areasfor the purpose ofthis sub.part if work is not intended in the

area (or at least aix months.

(h) "Underground uranium mine"

means a man-made underground excavation made for the purpose of removing material containing uranium for the principal purpose of recovering uranium.

(i) "Work" means mining activity done in the usual and ordinal'Y. course of developing and operating a mine.

§ 6 1 .22 Standard.

(a) An owner or operator ofan underground uranium mine subject to ibis subpart shall install and maintain bulkheads to isolate all abandOGed and temporarily abandoned areas according
to the following requirements:

(1) The bulkhead shall be a structure designed and constructed for long-term control ofthe isolated area and shall be sealed to minimize air leakage through

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## I Rules ·and Regulations 

### 15393

the bulkhead. The bulkhead shall be of sufficient structural strength to resist mechancial abuse, blasting shocks. air pressure differentials, and rock
movement for an extended period of time in the mine-operating environment. The basic bulkhead structure may consist of a timber or metal stud frame, covered with lumber, expanded metal lath, plywood, or other sheet products. It 

### may be a continuous nonporous membrane orit may support such a membrane. A sealant shall be applied
onto the basic structure and in the joints between the structure and the rock to form a continuous seal and radon barrier. The sea lant shall be of a type that will provide a protective seal, and will not easily crack or develop holes or leaks. A sealant may consist ofcoatings ofmortar, masonry, latex, uretane foam,

or similar materials

. A properly constructed and sealed bulkhead shall have no visible cracks or gaps.

(2) If

### negative pressure behind the bulkhead is used, then a maxim11m of 20 percent of the total volume of air contained in the isolated area canbe exhausted per day.

(3) As mine areas become abandoned

or temporarily abandoned after the

. applicable date ofthis standard, the mine owner or operator must install a · bulkhead in compliance with the provisions of§ 61.22(a) within 30 

### days of the area becoming abandoned or temporarily abandoned.

(b} Upon written application from an

owner or operator of an underground uranium mine subject to this subpart, the.Administrator may approve alternative bulkhead designs or construction, or other methods for iaolating abandoned or temporarily abandoned areas. if such alternatives

can be shown to provide isolation ofthe

area equivalent to the requirements of § 61.22(a)(1}.

§ 61.23 Alternative Standard.



### (a) 

### Ifcompliance with the requirements of§ 61.22 will result in increased radon-222 decay product concentrations in the active areas ofthe mine, will require workers to enter unsafe areas, or will otherwise be impractical to achieve because ofunique

or unusual circumstances. then the

owner or operator of an existing source (i.e., existing active mine) may apply to the Administrator for an alternative standard. The Administrator may establish an alternative standard if the**~pplicant** 

### demonstrates that an alternative is necessary to provide for the health and safety ofthe workers and will minimize the exposure ornearby individuals and the general population
to**radon-2~** 

### decay products, to the extent practical. Applications for an alternative standard shall be made within 90 

### days ofthe effective date of the standard and include the following information:

.

(1) The reasons for requesting an alternative:

(2) A description ofthe alternative requested:

(3) A description of all measures that have been taken or will be taken by the mine owner or operator to minimize the
exposure ofnearby individuals and the general population to radon-222 decay products, to the extent practical.

(4) 

### A schedule for complying with the alternative standard.

(b) 

### An inactive mine which again becomes active may request an alternative standard under§ 61.23(a)

. Application for an alternativ.e standard
must be submitted as part of an application for approval ofconstruction

ormodification as required under · § 61.07

. 

### (c) Requests for an alternative standard shall be sent to the Assistant Administrator for Air and Radiation (ANR-443), U

.S. Environmental · Protection Agency, 401 

### M Street, SW

.. Washington, 

### D.C. 20460.

§ 61.24 Bulkhead Inspection and Testing.



### An owner or operator of an · underground mine subject to the requirements of § 

### 61.22 shall conduct the following bulkhead Inspections and
tests:

(a) A visual inspection ofthe condition ofeach bulkhead required under § 

### 61

.22(a) shall be conducted every three months by a**qu~ ified**  

### representative ofthe mine owner or operator to determine if, in his or her judgment, the integrity ofthe bulkhead is in compliance with the requirements of § 

### 61.22(a)(1). A record ofeach inspection shall be made in accordance with the requirements of § 

### 61.26.

(b) For bulkheaded areas m'intained under negative pressure, measurement ofthe air exhaust rate froml the area shall be made at least evel'}( three months to determine**compl~ance** 

### with the requirement of§**61.22(a~(2).** 

### A record ofeach exhaust rate measurement shall be made in accordance with the requirements of § 

### 61.26. '

(c) Upon written applica4on from an

owner or operator of an underground uranium mine subject to**thi~** 

### subpart, the Administrator may approve alternative testing and inspection procedures ifsuch**altemat~ve** 

### procedures canbe shown to provide reasonable assurance that the mine is in compliance with the requirements of § 

### 61.22(a). § 61.25 Bulkhead Repair. 

### Bulkheads determined not to be in compliance with the requirements of § 

### 61

.22(a) during inspections required under § 61.24 shall be repaired within
ten days in accordance with the requirements of§ 61

.22(a)

§ &1.26 Rec:ordkeeplng.



### Records ofinspections and tests required under § 61.24 shall be maintained as described below. These records shall include a bulkhead identification number and location and the date ofeach inspection or test.

(a) The results of each inspection required under§ 61.24(a) shall be recorded as follows:

(1) A description ofthe condition of the bulkhead including identification of any damage and the extent ofdamages

.

(2) A determination that the bulkhead Is in compliance with the specifications of§ 61.22(a) or that repairs are needed.

(b) A record shall be maintained for each bulkhead repaired under the requirements of§ 61.25.

(c) A record shall be maintained for each airflow rate measurement conducted under the requirements of § 

### 61.24(b). These records shall show the results ofeach test and the method used. The percent of the total air volume behind the bulkheaded area which is exhausted per day at the measured flow
rate shall be recorded.

(d) Records ofInspections and tests shall be maintained at the mine and made available for inspect ion and copying by the Administrator for a minimum oftwo years.

(e) A current map or schematic of the mine showing the lo

_ cation ofeach bulkhead required under § 61

.22{a) and the approximate air volume of the isolated area shall be maintained. Each bulkhead shall be assigned an identification number which shall be used in inspections and tests, and the reporting requirements of §

### § 61.24 and 61.26. This map shall be kept.at the mine and be made available for review by the Administrator.
(Approved by the Office of Management and Budget under the control 

### number 2000-0115)

§ 61.27 Reporting Requirements.



### (a) An 

### owner or operator ofan underground uranium mine subject to the requirements ofthis subpart shall submit a certification to the Administrator byMarch 1

, 1986, and annually thereafter. This certification shall be based on information and data concerning the calendar year immediately preceding the required data for submission ofthe certification and shall consist ofa statement that the

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# i Rules and Regulations

bulkheading requirements of § 61.22(a)

or any alternative standard established under §61.23 have been implemented.

(b) 

### Ifa waiver ofcompliance is granted, this certification is to be submitted on a date scheduled by the Administrator. (Approved by the Office ofManagement and Budget under control number 206(H)115)

§ 81.28 Source Reporting and W81ver Request.

(a) The owner or operator of any existing source, or any new source to which a standard prescribed under this subpart is applicable which had an initial startup which preceded the effective date of a standard prescribed under this subpart shall, within 90 days after the effective date, provide the following information in writing to the Administrator:

(1) Name and address of the owner or operator:

(2) The location ofthe source: (3) A briefdescription ofthe nature, size, design, and method ofoperation of the mine including: (i) current or expected annual ore production rates, (ii) current cumulative ore production, (iii) expected cumulative ore production

over the life ofmine:

(4) The number of abandoned and temporarily abandoned areas in the mine and the number ofthese areas which are isolated by bulkheads: and

(S) A statement by the owner or operator ofthe source as to whether he

can comply with the standard prescribed in this subpart within 90 days ofthe effective date.

(b) An owner or operator ofan existing underground uranium m ine ( i.e.• existing source) unable to

**op~rate** in compliance with the standard prescribed under this subpart or lacking sufficient information to apply for an alternative standard within 90 days of the effective date ofthe standard may request a waiver ofcompliance with such standard for a period not exceeding two years from the effective date. Any request shall be in writing and shall include the following information:

(1) The reasons for requesting the waiver;

(2) A schedule for achieving compliance with t he standard, or if applicable, the alternative standard, including the steps which will be taken to come into compliance including a date by which each step will be achieved: and

(3) Interim emission control steps will be taken during the waiverperiod.

(c) Changes in the information provided under paragraph (a) of this section shall be provided to the Administrator within 30 days after such change, except that if changes will result from modification of the source, as defined In §§ 61.02, the provisions of § 61.07 and 61.08 are applicable.

(FR Doc. BS-9200 Fil ed 4-16-85; 8:45am!

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