National Emission Standards for Hazardous Air Pollutants; National Emission Standard for Radon Emissions From Phosphogypsum Stacks

SUMMARY: On June 3, 1992, EPA issued a final rule revising 40 CFR part

61, subpart R, the National Emission Standard for Radon Emissions From

Phosphogypsum Stacks (57 FR 23305, June 3, 1992). The Fertilizer

Institute (TFI) filed a petition seeking reconsideration of the 1992

rule pursuant to Clean Air Act section 307(d)(7)(B). This notice sets

forth the Agency's decision concerning the TFI reconsideration

petition.

EPA has decided to partially grant and to partially deny the TFI

petition for reconsideration. EPA will reconsider 40 CFR 61.205, the

provision of the final rule which governs distribution and use of

phosphogypsum for research and development, and the formula in 40 CFR

61.207(d). EPA will publish a separate Federal Register notice

convening a proceeding to reconsider these provisions shortly. EPA is

denying the remainder of the TFI petition. In this notice, EPA

summarizes the principal remaining objections by TFI. EPA also explains

why these objections are not of central relevance to the outcome of the

rule and therefore do not constitute a basis for reconsideration.

DATES: Under Clean Air Act sections 307(b)(1) and 307(d)(7)(B), TFI may

seek judicial review of the decision by EPA to partially deny its

August 3, 1992 petition only by filing a petition for judicial review

in the United States Court of Appeals for the District of Columbia

Circuit within 60 days of the date of publication of this notice in the

Federal Register.

FOR FURTHER INFORMATION CONTACT: Jacolyn Dziuban, Air Standards and

Economics Branch, Criteria and Standards Division (6602J), Office of

Radiation and Indoor Air, Environmental Protection Agency, Washington,

DC 20460, (202) 233-9474.

SUPPLEMENTARY INFORMATION:

I. Background

Phosphogypsum is a waste resulting from wet acid phosphorus

production. Phosphogypsum stacks are piles of waste or mines utilized

to store and dispose of phosphogypsum. EPA issued a National Emission

Standard for Hazardous Air Pollutants (NESHAP) applicable to radon

emissions from such stacks in 1989, 40 CFR part 61, subpart R (54 FR

51654, December 15, 1989). As part of that standard, EPA adopted a work

practice requirement that all phosphogypsum be disposed in stacks,

thereby permitting control and measurement of gaseous radon-222 which

is emitted when radium present in the phosphogypsum decays.

Subsequent to issuance of Subpart R, EPA received petitions for

reconsideration from The Fertilizer Institute (TFI), Consolidated

Minerals, Inc., and U.S. Gypsum Company. These petitioners objected to

the requirement that all phosphogypsum be disposed and managed in

stacks, because it operated to preclude various alternative uses of

phosphogypsum, including use of phosphogypsum in agriculture,

construction, and research and development. Because EPA had not fully

considered the implications of its work practice standard for

alternative uses, EPA agreed to convene a reconsideration proceeding in

which the risks associated with alternative uses and the procedures

under which alternative uses might be permitted could be evaluated (54

FR 9612, March 7, 1989).

Rather than setting forth one specific proposal for revision of

subpart R, EPA requested comment on a variety of substantive issues,

including specific types of proposed alternative uses of phosphogypsum

and the health risks associated with these alternative uses. EPA also

requested comment on four general options for regulation of alternative

uses: (1) No change in the work practice requirement, (2) changing the

definition of phosphogypsum to exclude from the work practice

requirement material with radium-226 concentrations up to 10

picocuries/gram (pCi/g), (3) permitting use of phosphogypsum in

research and development on processes to remove radium from the

phosphogypsum, and (4) permitting alternative use of phosphogypsum only

after specific permission from EPA.

After analyzing the risks associated with the various alternative

uses of phosphogypsum which were proposed and evaluating the comments

which were received, EPA issued a final rule revising subpart R (57 FR

23305, June 3, 1992). The approach which EPA ultimately adopted was a

hybrid of the options it had previously identified. For phosphogypsum

use in agriculture, EPA decided that it would be impractical to require

case-by-case approval. Based on its analysis of potential risks

associated with long-term use of phosphogypsum in agriculture, EPA set

a maximum upper limit of 10 pCi/g for radium-226 in phosphogypsum

distributed for use in agriculture. Rather than excluding material at

or below 10 pCi/g from the standard, EPA established sampling,

measurement, and certification procedures permitting such material to

be removed from stacks and sold for agricultural use. Based on analysis

of potential risks associated with the research and development use,

EPA decided to permit use of up to 700 pounds of phosphogypsum for a

particular research and development activity. EPA also decided to adopt

procedures permitting approval of other uses of phosphogypsum on a

case-by-case basis.

After EPA issued its final rule concluding the reconsideration

proceeding and revising subpart R, The Fertilizer Institute (TFI)

sought judicial review of the 1992 revisions of subpart R in The

Fertilizer Institute v. Environmental Protection Agency, No. 92-1320

(D.C. Cir.). TFI also filed a petition dated August 3, 1992 seeking

further reconsideration of the revisions of the rule pursuant to Clean

Air Act section 307(d)(7)(B). TFI, EPA, and ManaSota-88, another

petitioner who sought review of the 1992 rule in ManaSota-88 v.

Browner, No. 92-1330 (D.C. Cir.), later reached an agreement to jointly

move the D.C. Circuit Court of Appeals to stay judicial review of the

1992 rule, and the Court granted the motion. As part of that agreement,

EPA agreed to make a final decision whether to grant or to deny the TFI

petition for reconsideration by January 31, 1994. This notice sets

forth the Agency's decision concerning the TFI reconsideration

petition.

II. Standard for Reconsideration

Under Clean Air Act section 307(d)(7)(B), the EPA Administrator is

required to convene a reconsideration proceeding if: (1) The person

raising an objection to a rule can demonstrate to the Administrator

that it was impracticable to raise such objection within the time

permitted for public comment or the grounds for the objection arose

after the period for public comment, and (2) if the Administrator

determines that the objection is of central relevance to the outcome of

the rule. Therefore, reconsideration is not required if the objections

by a petitioner were raised or could reasonably have been raised during

the pendency of the rulemaking. Moreover, even in the circumstance

where a particular objection could not have been raised earlier,

reconsideration is not required if EPA determines that such objections

would not have altered the outcome of the rule had they been raised

earlier.

TFI argues in its petition that EPA should reconsider the entire

1992 rule revising subpart R because the 1989 notice convening the

reconsideration proceeding did not specify, or provide an opportunity

for comment on, the details of the technical methodology which EPA

subsequently utilized in analyzing the risks associated with

alternative uses of phosphogypsum. However, EPA does not believe that

it was obligated to select and specify each of the technical models to

be utilized in its analysis and to describe all of the analytic

assumptions to be utilized before convening the reconsideration

proceeding. TFI also argues in its petition that a number of the

elements of the rule as it was promulgated were not specifically

proposed for notice and comment. In general, EPA believes that the

provisions of the rule adopted in 1992 were a logical outgrowth of the

options described in the 1989 reconsideration notice and the comments

received concerning those options.

EPA acknowledges that TFI did not have sufficient information to

state many of the detailed technical objections set forth in its

petition for reconsideration within the period provided for public

comment. However, under the criteria set forth in CAA section

307(d)(7)(B), it is still necessary for EPA to assess the substantive

significance of each of these objections to determine whether it is of

central relevance to the outcome of the rule and therefore an

appropriate basis for reconsideration.

Applying the criteria for reconsideration set forth in section

307(d)(7)(B) to the August 3, 1992 TFI petition, EPA has concluded that

certain objections raised by TFI do warrant convening a reconsideration

proceeding concerning particular provisions included in the 1992

revisions to Subpart R, but that the remaining objections by TFI do not

warrant reconsideration of the remaining provisions of the 1992 rule.

III. Decision to Partially Grant Petition

In its petition, TFI objects that the EPA analysis of the potential

risks associated with the use of phosphogypsum in research and

development assumes an emanation rate for radon from phosphogypsum in

the laboratory 40 times greater than the rate for phosphogypsum in

stacks, and that EPA has therefore greatly overestimated the risk

presented by the research and development use. TFI also argues that the

analysis by EPA assumed that normal good laboratory practices, such as

segregated storage of hazardous materials, limiting removal of

materials to an as needed basis, appropriate ventilation, and

appropriate disposal of used material, would be disregarded.

The analysis by EPA of the potential risks associated with the

research and development use assumed that all of the free radon

generated by phosphogypsum containing 26pCi/g radium-226 would be

released to a small laboratory room with a total volume of 64 cubic

meters and an air volume of 50 cubic meters. The EPA analysis thus

assumed that none of the radon would be retained in the physical matrix

of the phosphogypsum long enough to permit further decay the radon and

adsorption of the decay products, which would prevent release of

gaseous radon to the laboratory environment. While there are certainly

some experiments or circumstances where all of the radon generated by

decay of radium in the phosphogypsum could be released in the

laboratory, EPA has concluded that this would be unusual and that such

high emanation rates would be infrequent.

In addition, EPA discovered during its review of the analysis of

potential risks associated with the research and development use that

EPA assumed in its estimation of radon emissions to the laboratory

environment that five 700 pound drums would be stored or utilized in

the same area of the laboratory, rather than the single 700 pound drum

permitted by the rule. As a consequence, the portion of the risk to

laboratory personnel attributable to radon emissions was overestimated

by a factor of five. In view of these conclusions, EPA has determined

that the objections by TFI are of central relevance to the provision

limiting use of phosphogypsum in research and development to no more

than 700 pounds, and that EPA should request further comment on the

assumptions to be utilized in analyzing the risks associated with the

research and development use.

In its petition, TFI also argues that it is not clear from the text

of the 1992 rule whether more than one research and development

activity utilizing 700 pounds of phosphogypsum would be permitted at a

single facility, as well as whether or not a single research activity

would be limited to a total of 700 pounds or only to 700 pounds at any

given time. TFI states that it assumes that multiple research and

development activities each utilizing 700 pounds of phosphogypsum would

be permitted at a single facility, and that the 700 pound limit applies

only to the amount of phosphogypsum on hand at any given time, but

requests that EPA clarify the rule. EPA believes that TFI has correctly

construed the rule and questions the need for further clarification of

the existing rule. However, the fact that a given laboratory worker

might be exposed to radiation as a result of more than one research and

development activity utilizing phosphogypsum was not considered in the

EPA risk analysis. Accordingly, EPA has decided that it will also

request comment on whether there should be any limit on multiple

research and development activities at a single facility or by a

particular investigator, and how the possibility of greater exposures

attributable to multiple research and development activities should be

accounted for in the EPA analysis.

In its petition, TFI objects that it is not clear what purpose is

served by requiring owners or operators to conduct sampling or

measurement of radium-226 in phosphogypsum distributed for use in

research and development, because there is no quantitative limit on the

amount of radium-226 which phosphogypsum distributed for this use may

contain. Because there is no limit on the amount of radium permitted in

phosphogypsum distributed for research and development use, EPA assumed

in its analysis of potential risks associated with such use that the

phosphogypsum would contain high levels of radium. EPA believes that in

most instances analysis of the radium-226 content in phosphogypsum

distributed for use in research and development will be necessary as

part of the research activity. However, EPA has concluded that

requiring certification documents accompanying phosphogypsum

distributed for use in research and development to include quantitative

analyses of radium content is not necessary to monitor compliance.

Accordingly, EPA has decided that this objection by TFI is also of

central relevance to the outcome of this provision.

In view of the multiple objections by TFI which are of central

relevance to the outcome of 40 CFR 61.205, the provision of the revised

Subpart R governing distribution of phosphogypsum for use in research

and development, EPA has decided to partially grant the TFI petition by

convening a proceeding to reconsider 40 CFR 61.205. To implement this

decision, EPA is preparing and will publish shortly a notice of

reconsideration specifying the specific subjects on which further

comment will be requested and the range of options to be considered.

In its petition, TFI objects that the formula set forth in 40 CFR

61.207(d), which is used to establish the number of samples necessary

to determine a representative average radium-226 concentration, is

ambiguous, because it does not specify the amount of allowable error.

EPA agrees with this objection. The failure to include an allowable

error component in the formula was an inadvertent omission. EPA

believes that it would not be necessary to convene a reconsideration

proceeding for the sole purpose of correcting this inadvertent

omission, but has decided to include 40 CFR 61.207(d) among the

provisions to be reconsidered. To assist affected facilities in

complying with the existing rule while the reconsideration proceeding

is pending, EPA will provide specific guidance in the notice of

reconsideration concerning selection of an appropriate error component.

IV. Decision to Partially Deny Petition

EPA has carefully reviewed all of the remaining objections set

forth in the TFI petition for reconsideration. Based on that review,

EPA has concluded that none of the remaining technical objections by

TFI to the EPA analysis of the potential risks of phosphogypsum use are

of central relevance to the outcome of the 1992 rule. In addition, EPA

has determined that some of the remaining policy objections by TFI

could have been raised during the public comment period, and that none

of the remaining policy objections is of central relevance to the

outcome of the rule.

Based on its review of the remaining objections in the TFI petition

for reconsideration, EPA is denying the TFI petition with respect to

all provisions in the rule not specifically included in the decision to

grant reconsideration set forth above. The Agency's response to each of

the remaining TFI objections is summarized below.

A. Technical Objections

Objection: The radon emanation coefficient of 0.3 for phosphogypsum

is too high. Field observations (HP91) and the PATHRAE model (EPA87)

suggest the radon emanation coefficient for phosphogypsum in soil

should be 0.2. The coefficient used is 50 percent larger than suggested

by empirical data, but no explanation is given for why the higher value

was selected.

Response: The selection of 0.3 for the radon emanation coefficient

(E) is based on 30 measurements using phosphogypsum from four sites in

central Florida and Texas (RO88). As this reference is not publicly

available, it was not cited in the Background Information Document

(BID). The measurements were made at typical in-situ moistures for

phosphogypsum stacks. The arithmetic average of these data is about

0.35. Thus, the value of 0.3 used in the BID is reasonable and

applicable.

The data and other information (NI82) show the dependence of E on

moisture. At lower moisture levels E increases significantly with

moisture. This is also demonstrated in the work of van Dijk and deJong

(HP91) referenced by TFI. As their Figure 4 shows, E for phosphogypsum

can increase by more than 50 percent as equilibrium moisture increases.

The E values of 0.18 and 0.19, reported in their Table 2 and referenced

by TFI, are for nearly their driest conditions. As they were interested

in the effects of using phosphogypsum in building materials, these

lower values were appropriate. However, the exalation rates that they

measured at higher moistures give E values of about 0.28. This is

consistent with the value of 0.30 used in the risk assessments.

Moisture saturations in soils under residences are expected to be near

the values in the Rogers measurements and closer to the higher moisture

measurements by van Dijk and deJong.

The higher emanation coefficients are further confirmed in field

measurements of the specific radon flux from the surface of

phosphogypsum stacks. In 1985, Dr. C.E. Roessler (University of

Florida) determined that the specific radon flux from phosphogypsum

stacks in central Florida was 1 pCi/m2-s per pCi/g of Ra-226 in

the phosphogypsum. This value requires an E value of at least 0.29.

TFI also commented that an E of 0.2 was used in the PATHRAE model

(EPA87). This value was used in an example problem in the reference.

However, the example problem was for soil, not phosphogypsum, and

should not be construed as a recommendation for all cases.

Objection: The radon diffusion for concrete is given as 16 m2/

y. Published measurements of radon diffusion in concrete (HP80a, HP83)

provide values that are factors of 8 to 15 lower. Use of the lower

radon diffusion coefficients would reduce the indoor radon risks by a

factor of about two.

Response: The value of 16 m2/y (5.1 x 10-3 cm2/s)

for the radon diffusion coefficient of concrete (Dc) is the upper

end of the range of Dc's measured for residential concretes by

Nielson and Rogers (NI91). The upper end of the range was used because

PATHRAE only considers radon diffusion as the entry mechanism for soil

radon. While diffusion may dominate radon entry (TA90, RO90), advective

transport is also a factor and may dominate under some circumstances

(RO90, LO90). The value that was used for Dc in the risk

assessments partially accounts for the radon entry by advection.

TFI refers to Dc measurements made by Zapalac (HP83) and

Stranden and Berteig (HP80a). Zapalac reports Dc values of 3.3 x

10-4 cm2/s and 6.0 x 10-4 cm2/s for concretes

with densities of 2.3 and 2.4 g/cm3. The measurements by Rogers

and Nielson (RO90) also give the dependence of Dc on the concrete

density. The residential concretes that they tested had densities

generally of 2.1 g/cm3 or less. For the densities used by Zapalac,

the Rogers and Nielson correlation predicts Dc values of 1.2 x

10-4 and 4.0 x 10-4 cm2/s. Thus, the data used in the

risk assessments are consistent with Zapalac's data.

Stranden and Berteig did not give the densities for their concrete,

so a direct comparison is not possible. However, it is worth noting

that since the Stranden and Berteig measurements relied only on the

radon generated within the concrete, they are not a very sensitive

measure of Dc. Since a significant fraction of residential

concretes have densities less than 2.2 g/cm3, the value of 5.1 x

10-3 cm2/s for Dc is reasonable for the risk

assessments.

Objection: The radon decay product equilibrium fraction of 0.5 is

the upper bound of the range of 0.3 to 0.5 found in the Florida

Statewide Radiation Study. The average indoor radon equilibrium

fraction from houses where the radon concentrations ranged from 0.4 to

>8 pCi/l was 0.42. The National Council on Radiation Protection and

Measurements (NCRP) in its Report 94 and the United Nations Scientific

Committee on the Effects of Atomic Radiation (UNSCEAR) recommend 0.4 as

an indoor equilibrium fraction. The selected value of 0.5 is also

inconsistent with the assumption of 2 air changes per hour. Krisiuk

(HP80b) gives a value of 0.36 for a ventilation rate of 2 air changes

per hour. If other removal mechanisms are considered (e.g., plateout

and deposition), the equilibrium would be even lower. Use of 0.5 for

the equilibrium fraction results in overestimating the risks from

indoor radon exposure by a factor of at least 1.4.

Response: The EPA's radon risk factor incorporates a 0.5

equilibrium fraction. The value of 2 air changes per hour was not

chosen to be consistent with the radon decay product equilibrium

fraction. If they were made consistent, then 1 air change per hour

(HP80b) would have been used. The value of 1 air change per hour is

about the average for residences in the United States (NA88), and

results in an average equilibrium fraction of about 0.5. Thus, the use

of 2 air changes per hour in the risk assessments is non-conservative.

Objection: Based on estimates of the NCRP in Report No. 45, the

PATHRAE model overestimates the effective gamma dose rate by a factor

of 2.5.

Response: For Scenarios 1 and 2, the BID gives an annual external

gamma dose equivalent of 3.5 mrem/y from a soil Ra-226 concentration of

0.69 pCi/g. This is equal to a dose rate of 2.5 urad/h per Pci/g of Ra-

226. TFI references the 1.6 urad/hr per pCi/g value recommended by the

NCRP (NCRP75 and NCRP87). Thus, the NCRP's value is lower than the

PATHRAE results by 36 percent, not the factor of 2.5 claimed by TFI.

The external gamma dose rate at a given distance above soil

containing Ra-226 depends on the source geometry and the self-

absorption of the radiation in the soil. For the conditions being

assessed, an infinite plane best describes source geometry and the

PATHRAE model used an infinite plane dose factor for Ra-226 and its

decay products of 1.67 x 10-4 mrem/y per pCi/m2. As this

value is nearly the same as the value of 1.69 x 10-4 mrem/y per

pCi/m2 used by the DOE (DOE88), it does not appear to be too high.

The effect of self-absorption is quite variable and depends on the soil

density and the low gamma energy cutoff value. The NCRP's theoretical

value is based on work by Beck (BE75), which assumes a soil density of

1.6 g/cm3 and used 50 KeV as the low energy cutoff values. These

differences, particularly the difference in the low energy cutoff

values, account for the differences between the BID and the results

that would be obtained using the NCRP's value of 1.6 urad/hr per pCi/g.

It should also be noted that both values (1.6 urad/hr per pCi/g and 2.5

urad/hr per pCi/g) are within the variability of field measurements.

Objection: The use of a 70 year exposure period for residential

scenarios is inconsistent with the Superfund policy of using 90th

percentile estimates. The 90th percentile value is 30 years.

Response: The BID generally reports lifetime risk per year of

exposure. However, in Scenario 7, the risks for a lifetime of exposure

are presented by multiplying the risk per year of exposure by 70 years.

This is consistent with the EPA's policy under the Clean Air Act which

was explained in the preamble to the 1989 National Emission Standards

for Radon Emissions from Phosphogypsum Stacks (54 FR 51661) and which

has been used in these rulemaking proceedings.

However, as explained in the preamble, the difference that would be

caused by assuming a shorter period of exposure is not very

significant. For an assumed constant rate of exposure, people receive

over 60% of their total lifetime risk during their first nineteen

years. To change the period of exposure from 70 years to the first 19

years of life would change the final results by less than a factor of

two.

Objection: Radioactive decay during the 70-year residential

exposure period is neglected.

Response: Neglecting radioactive decay during the 70-year

residential exposure period introduces a negligible conservatism to the

results. Accounting for radioactive decay would have reduced the

estimated risks by about 1.5 percent.

Objection: The BID fails to account for removal of soil during home

construction at former phosphogypsum use sites.

Response: Some home construction may involve the removal of the

contaminated soil. However, it is more likely that the homes would have

the contaminated soil under or adjacent to them. Since the analysis

focused on the potential risks to the most exposed members of the

population, assuming that the contamination remains under and adjacent

to any homes that are built is reasonable.

Objection: The derivation of the presumptively safe level of 10

pCi/g Ra-226 for phosphogypsum used in agriculture is based on the 95th

percentile application rate of 2,700 lb/acre for 100 years. Using the

90th percentile rate, per Superfund policy, would be more appropriate.

More importantly, the application rate of 2,700 lb/acre is for soil

reclamation rather than soil productivity. Soil reclamation would not

require applications at this rate over a 100-year period. By combining

the application rate for soil reclamation with the frequency rate for

soil productivity the EPA has greatly overestimated the total

phosphogypsum application that would occur over the 100-year period.

Response: Superfund guidance is not necessarily applicable under

this NESHAP. However, TFI has not correctly stated the Superfund

guidance. That guidance for calculating reasonable maximum exposure

calls for the choice of 95th percentile values where available, or 90th

percentile values where 95th percentile values are not available.

The 95th percentile application rate for phosphogypsum used in

agriculture was calculated from data reported by TFI, based on a

questionnaire they sent to users of phosphogypsum (Docket A-79-11, XV-

D-100A, appendix, Tab 38). The 95th percentile was based on considering

application rates for a variety of crops produced in California and for

peanut production in the South, based on the assumption that

agricultural usage of phosphogypsum is about equally split between the

California and the remainder of the U.S. Although the data from

California show much higher application rates than those for peanuts,

we do not believe that California's rates are necessarily associated

with reclamation. Phosphogypsum is used for land reclamation in

California; however, an expert on the use of phosphogypsum in

California estimates that the application rate for reclamation is about

10,000 pounds per acre, considerably higher that the rates reported in

the TFI questionnaire. He also estimates that the application rate for

production is approximately equal to the rates reported in the TFI

questionnaire (Docket A-79-11, XVII-B-41).

Objection: The assessment of agricultural use does not consider the

differing application rates in different geographic areas of the

country.

Response: The risk analysis in the BID gives risks for various

application rates. Use of the 95th percentile application rate to

select a single value for the maximum permissible radium-226 content in

phosphogypsum distributed for agricultural use greatly simplifies

compliance and enforcement procedures.

Objection: The method prescribed for determining Ra-226

concentrations is for airborne effluents, not solids.

Response: The rule references Method 114 in appendix B of part 61.

Method 114 provides requirements for: (1) Stack sampling of effluents;

(2) radiochemical methods for determining the quantity of radionuclides

in a sample; and (3) quality assurance methods. Clearly, the portions

of Method 114 that relate to the collection of the effluent sample are

not applicable to determining the Ra-226 content of phosphogypsum

removed from a stack. However, the portions of Method 114 that relate

to radiochemical methods of determining the quantity of Ra-226 present

in the phosphogypsum (i.e., ``the principles of measurement'') and the

specified quality assurance methods are valid regardless of how the

sample was obtained.

B. Policy Objections

Objection: The EPA analysis of potential risks and the EPA decision

criteria with respect to the use of phosphogypsum in road construction

are absurd, because even naturally occurring materials would not meet

the EPA standard for a presumptively safe level of exposure to

radioactivity.

Response: It is well known that naturally occurring radium-226

levels in soil can release amounts of radon which are potentially

hazardous to occupants of structures built on such soil. Phosphogypsum

can contain radium-226 levels far in excess of the amount of activity

naturally present in soil. It is not absurd for EPA to take actions to

control the additional risks associated with the higher activity levels

in phosphogypsum simply because naturally occurring construction

materials may also present a risk in some circumstances.

Objection: The requirement that a person generating phosphogypsum

must first place it in a stack, and then measure and certify the radium

activity in the stack, before removing phosphogypsum from the stack and

distributing it for alternative use is cumbersome and unnecessary.

Instead, if phosphogypsum is designated for reuse, segregated, and

routed to a distribution holding point, the radium-226 content of the

phosphogypsum can be measured at either the segregation or the

distribution point.

Response: The provisions permitting distribution of phosphogypsum

for alternative uses are specific exceptions to the work practice

requirements which require persons generating phosphogypsum to dispose

of the material in a stack and to manage the stack in a specified

manner. For the provisions in the rule to operate properly, the

generator of phosphogypsum must determine that a given quantity of

phosphogypsum conforms to all of the requirements for distribution for

alternative uses before such distribution occurs. To the extent that

TFI is suggesting that persons other than those who generated the

phosphogypsum in the first instance should be permitted to measure the

radium-226 activity levels after distribution of the phosphogypsum has

already occurred, this cannot be reconciled with the Agency's objective

to assure safe disposal in managed and monitored stacks of all

phosphogypsum which does not meet the threshold requirements for

distribution for alternative uses.

EPA notes that 40 CFR 61.201(c) defines any pile of phosphogypsum

waste as a phosphogypsum stack. If the person who generates the

phosphogypsum in the first instance wishes to segregate phosphogypsum

designated for alternative use in a separate stack and measure the

activity levels in that stack separately, the rule permits this

approach. However, any materials in any additional stack which are not

lawfully distributed for an alternative use must be managed by the

owner or operator in the manner specified by the rule.

Objection: The limitation to 700 pounds of phosphogypsum for each

specific research and development activity necessarily means that

research and development in the field will be impossible.

Response: EPA notes that it has decided to reconsider the 700 pound

limitation. However, 40 CFR 61.205 was designed to permit research and

development activities involving phosphogypsum to proceed in the

laboratory, not to authorize large scale field research. Proposals to

conduct field studies utilizing phosphogypsum should instead be

submitted for prior EPA approval pursuant to 40 CFR 61.206.

Objection: The procedures for certification in 40 CFR 61.208 are

overly burdensome and unnecessary. They require a multi-party paperwork

trail for materials that are presumptively safe. EPA should just

require the person who generates phosphogypsum to certify at the end of

the year that all of its shipments met applicable legal requirements.

Response: EPA believes that the procedures requiring distributors,

retailers, or resellers to prepare certification documents and to

retain copies of certification documents provided by the person from

whom the phosphogypsum was obtained are necessary to adequately monitor

compliance with the requirements in the rule. Without such

documentation, it would be much more difficult or even impossible to

investigate and take appropriate enforcement action if non-conforming

phosphogypsum is found to have been distributed or sold for an

alternative use. EPA notes that farmers or agricultural end-users who

purchase phosphogypsum for an agricultural use are not required to

prepare or maintain records, but that distributors who sell

phosphogypsum for an agricultural use must do so.

Objection: Risks associated with phosphogypsum use should be

controlled by state and local governments through restrictions on

building construction rather than by EPA.

Response: EPA hopes that state and local governments will adopt

appropriate measures to control hazards associated with radon emissions

at building sites. However, EPA does not believe that it is appropriate

for EPA to sanction specific activities which unduly increase the

radium content of the land and the risks associated with building

construction, based on an assumption that state or local building codes

will mitigate the resultant problem.

V. Judicial Review

The decision by EPA to partially deny the August 3, 1992 TFI

petition for reconsideration is final agency action based on a

determination of nationwide scope or effect. TFI may seek review of the

decision by EPA to partially deny its petition in the United States

Court of Appeals for the District of Columbia Circuit within 60 days

from the date this notice is published in the Federal Register. EPA

notes that TFI has previously agreed that, if TFI seeks judicial review

of the decision by EPA to partially deny its petition for

reconsideration, TFI will move to consolidate such review with the

review of the 1992 rule which is currently pending in The Fertilizer

Institute v. Environmental Protection Agency, No. 92-1320 (DC Cir.) and

ManaSota-88 v. Browner, No. 92-1330 (DC Cir.).

The decision by EPA to partially grant the TFI petition does not

constitute final agency action and is therefore not presently subject

to judicial review. After EPA takes final action in the resulting

reconsideration proceeding, any person who participated in that

proceeding may seek judicial review of such action.

VI. References

BE75 Beck, H.L., ``The Physics of Environmental Gamma Radiation

Fields,'' Proceedings, Natural Radiation in the Environment II,

1975.

DOE88 U.S. Department of Energy, External Dose-Rate Conversion

Factors for Calculation of Dose to the Public, DOE/EH-0070, 1988.

EPA87 U.S. Environmental Protection Agency, Low-Level and NARM

Radioactive Wastes Model--PATHRAE-EPA Methodology and Users Manual,

EPA 520/1-87-028, 1987.

HP80a Stranden, E. and Berteig, L., ``Radon in Dwellings and

Influencing Factors,'' Health Physics 30:275, 1980.

HP80b Krisiuk, E.M., ``Airborne Radioactivity in Buildings,'' Health

Physics 38:199, 1980.

HP83 Zapalac, G.H., ``A Time-Dependent Method for Characterizing the

Diffusion of 222Rn in Concrete,'' Health Physics 45:377, 1983.

HP91 van Dijk, W. and deJong, P., ``Determining the 222Rn

Exhalation Rate of Building Materials Using Liquid Scintillation

Counting,'' Health Physics 61:501, 1991.

LO90 Loureiro, C.O., et al., ``Three-Dimensional Simulation of Radon

Transport into Houses with Basements Under Constant Negative

Pressure,'' Environmental Science and Technology 24:1338, 1990.

NA88 Nazaroff, W.W. and Nero, A.V., Radon and Its Decay Products in

Indoor Air, pp. 131-157, John Wiley & Sons, New York, 1988.

NCRP75 National Council on Radiation Protection and Measurements,

Natural Background Radiation in the United States, NCRP Report No.

45, 1975.

NCRP87 National Council on Radiation Protection and Measurements,

Exposure of the Population in the United States and Canada from

Natural Background Radiation, NCRP Report No. 94, 1987.

NI82 Nielson, K.K., ``Radon Emanation Characteristics of Uranium

Mill Tailings,'' Proceedings of the Fifth Symposium on Mill Tailings

Management, pp. 355-567, Colorado State University Press, 1982.

NI91 Nielson, K.K., and Rogers, V.C., ``Radon Entry into Dwellings

Through Concrete Floors,'' Proceedings of the 1991 International

Symposium on Radon and Radon reduction Technology, Philadelphia, PA,

EPA-600/9-91-37c, 1991.

RO88 Rogers, V.C., Characterization of the Former Borden Property in

Texas City, Texas, Rogers and Associates Engineering Corp., RAE

8602/1-2, 1987.

RO90 Rogers, V.C. and Nielson, K.K., ``Benchmark and Application of

the RAETRAD Model,'' Proceedings of the 1990 International Symposium

on Radon and Radon Reduction Technology, Atlanta, GA, EPA/600/9-90/

005c, 1990.

TA90 Tanner, A.B., ``The role of Diffusion in Radon Entry in

Houses,'' Proceedings of the 1990 International Symposium on Radon

and Radon Reduction Technology, Atlanta, GA, EPA/600/9-90/005c,

1990.

Dated: March 7, 1994.

Carol M. Browner,

Administrator.

[FR Doc. 94-5993 Filed 3-23-94; 8:45 am]

BILLING CODE 6560-50-P