ML19262B507
| ML19262B507 | |
| Person / Time | |
|---|---|
| Issue date: | 12/07/1979 |
| From: | Eadie G NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Scarano R NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| Shared Package | |
| ML19262B504 | List: |
| References | |
| FOIA-80-529, FOIA-81-8, REF-WM-28 NUDOCS 7912280139 | |
| Download: ML19262B507 (5) | |
Text
S ff Io, UNITED STATES y h
( ',g NUCLEAR REGULATORY COMMISSION 3 p.4
.t j WASHINGTON, D. C. 20555 DEC 0 71979 MEMORANDUM FOR:
Ross A. Scarano, Chief Uranium Recovery Licensing Branch FROM:
Gregory G': Eadie Uranium Recovery Licensing Branch
SUBJECT:
SUMMARY
F THE CHURCH ROCK ENVIRONMENTAL IMPACT ASSESSMENT EFFORTS The following summary is intended to provide a general outline of the specific tasks and responsible agency's involvement in the assessment of the environmental impact of the UNC Church Rock uranium mill tailings dam failure. As of this date, in addition to New Mexico and Arizona's activities, at least four federal agencies are actually conducting some type of evaluation of the situation based mostly on their expertise or legislative mandate. This outline is meant to add some perspective to these separate efforts, and hopefully will aid in the ultimate coordination of all these activities to provide for the collection and adequate review of all available and necessary information in order to insure the protection of the public health and safety. These efforts will supplement the on-going activities of UNC, as described in their letter dated September 12,1979 and per recommendations of the New Mexico Environmental Improvement Division (NMEID)
(see Enclosures 1 and 2).
The general assessment work plan may be outlined as follows; with more specific descriptions of the various tasks included in the discussions:
Task I: Establish Soil Clean-Up Criteria Task II: Assess Existing Contamination Task III: Verify Soil Clean-Up Efforts Task IV:
Release Area for " Unrestricted Use" Task V:
De' fine Continued Monitoring Programs Task VI:
Issue Final Report Task I:
Establish Soil Clean-Up Criteria The goal of this task was to establish acceptable soil / sediment radiological clean-up criteria which are protective of public health.
In response to a request by the State of New Mexico, and in cooperation with the NMEID, acceptable levels of residual radioactive contamination of the soil and sediments of the affected areas of the Rio Puerco were provided in the NRC letter dated August 23,1979 (see Enclosure 3). Based on an evaluation of the limited data available at that time, it was concluded that an effective clean-up program could be conducted by evaluating the thorium-230 and radium-226 concentrations in soils / sediments. Acceptable clean-up levels were established to be no greater than 30 pCi/g of thorium-230 and 10 pCi/g of radium-226. )b00,
391228o/3 7
Ross A. Scarano Task II: Assess Existing Contamination The goal of this task is to determine the extent of contamination, both radiological and trace metal constituents, for all possible environmental pathways.
- 1) Soil / Sediment The areas of concern include the Rio Puerco and affected areas in both New Mexico and Arizona, plus background locations. Specific details of this sub-task are described in the NMEID letter dated September 25, 1979 (see Enclosure 4). At that time, it was requested that about 1400 additional soil samples from the affected areas should be collected under the direct supervision of NRC/NMEID personnel using a standardized sampling technique consisting of an 11 cm diameter disk of 5 cm depth.
Radiological analyses of these solid samples were provided within a matter of days of sample collection by means of sophisticated radiation detectors operated on-site at the UNC Church Rock Mill complex by scientific personnel from the Battelle Pacific Northwest Laboratories (BPNL) under contract to the NRC. This extensive soil sampling scheme was completed about October 12, 1979, and the review and interpretation of these analytical results should be accomplished by the end of January by the NRC, NMEID, and with the assistance of BPNL statisticians under contract to NRC (see Enclosure 5).
(The trace metal concentrations in affected soils is being evaluated by NMEID.) Also, the above radiological data has been provided daily to UNC in order to aid them in the identification of contaminated areas and to evaluate their soil clean-up efforts.
- 2) Surface and Ground Waters This sub-task is described in the EPA /IHS correspondence dated August 15, and October 18,1979 (see Enclosures 6 and 7). Surface water monitoring (in addition to UNC monitoring efforts) extends from the mine discharge area, past the mill site and down the Rio Puerco to Chambers, Arizona. This sub-task is scheduled for 35 weeks post incident (ending about mid-March,1980) and is being conducted by USEPA-Region IX, Arizona DOH and New Mexico EID. Ground water sampling is scheduled for about 68 weeks post incident, ending about October 1980, and is being conducted by the IHS, but with NMEID conducting its own monitoring program through mid-March 1980. At this time, it appears that no well sampling program has been established to monitor the local Navajo wells and indications are that several of these wells are presently being used for human consumption. Also, local Navajo wells may be directly influenced by any contamina-tion resulting from the dam failure, and it would seem prudent that a special effort to sample such representative Navajo ground water wells should be initiated as soon as possible by the responsible agencies.
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Ross A. Scarano 3) Airborne Particulates Air sa'mpling in the vicinity of the clean-up operations, plus routine sampling at a station near East Galiep has been conducted by NMEID. The documentation and results of this sub-task are not available at this time, and it has beea indicated that NMEID will periodically collect additional air samples as deemed necessary.
- 4) Livestock This sub-task has been initiated as described in the NMHSD letter dated September 13,1979 (see Enclosure 8). The IHS has supervised the collection and slaughtering of 2 cows, 4 sheep, and 1 goat selected as representative of
" exposed" animals plus 1 cow and 1 sheep as " control" animals. Radiological analyses are being performed at the USEPA Las Vegas Facility, but complete results are not expected until the end of December,1979. A preliminary evaluation of the suitability of local livestock for human consumption has been completed by NRC based on the limited data available at this time (see Enclosure 9). The estimated total human dose from typical livestock ingestion appears to be less than 240 mrem.
Further evaluations by the IHS, in consultation with other health agencies, should be completed for both radiological and trace metal constituents, when the final data are available.
- 5) Vegetation At this time, no supplemental vegetation sampling has been proposed; nor is it deemed necessary.
- 6) Gamma Radiation Surveys The ARMS flight of the Rio Puerco area was completed during the week of October 12, 1979 under an NRC contract. To date, no new information has been reported but when made available, this information will be incorporated with the soil sampling data as obtained from sub-task 1 above.
Since soil sample results.show essentially background levels of radium-226, and the extensive groundlevel gamma surveys reported by UNC also confirm only background exposure rates, no further gamma surveys are deemed necessary at this time.
- 7) Human Studies As indicated in the CDC Press Release dated September 25,1979 (see 0), six Navajo children, selected on the basis that they were among the maximally exposed population, showed no elevated levels of in_ vivo radioactivity as determined by whole body counting techniques at LASL. Urine bioassay results are not available at this time. No further human sampling has been proposed; nor are any deemed necessary.
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Ross A. Scarano Task III: Verify Soil Clean-Up Efforts The goal of this task is to define the extent and depth of soil / sediment contamination of the affected areas of the Rio Puerco in both New Mexico and Arizona,.and to provide inventory estimates of the radioactivity removed and of the residual contamination. As described in Enclosure 5, the NRC and NMEID are presently involved in the collection, review, and interpretation of the soil /
sediment sampling prograq and this effort should be completed about the end of January,1980. Also, a verification soil sampling program is to be established by the NMEID with the assistance of NRC, to document the actual condition of the area and to insure compliance to the clean-up criteria.
Task IV: Release Area for " Unrestricted Use" The goal of this task is to insure that residual contamination of soil / sediment in the affected arroyos will be protective of the public health and safety.
At this time, the soil / sediment clean-up criteria are 30 pCi/g for thorium-230 and 10 pCi/g for radium-226. However, preliminary data indicates that the radium levels are, on the average, less than 5 pCi/g. An evaluation of the radiolgical dose assessment models has been reported by the NRC (see Enclosure 11). Computer dose modeling estimates indicate that the maximally exposed individual would receive a bone dose of about 5.5 mrem per year if exposed for an entire year to resuspended dust with residual cotamination at the clean-up criteria levels.
However, until UNC has effectively completed the clean-up of all affected areas of the Rio Puerco, and upon verification by the NMEID of acceptable levels of residual contamination, it would seem prudent to continue to discourage the use of the Rio Puerco for domestic, irrigation or livestock watering purposes.
The " warning signs" should be removed only after the Rio Puerco has been released by the NMEID for " unrestricted use."
Task V: Define Continued Monitoring Programs The goal of this task is to determine the need for any necessary monitoring program which would be required after the area has been returned to unrestricted use.
As indicated above, the soil / sediment clean-up program does not fully resolve the question of potential contamination of the ground water system. This can probably only be answered through continued ground water monitoring over an extended time period beyond 1980. Such an effort should continue to be the responsibility of UNC with supplemental orograms directed by NMEID, AZD0H, EPA, or IHS, as deemed necessary.
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Ross A. Scarano The need for additonal soil / sediment or air sampling to monitor the actual contamination in the area post clean-up would best be determined after reviewing all pertinent data from sub-task 1 above.
Task VI:
Issue Final Report The goal of this task is,to provide a final public report containing all available information regarding the. environmental impact assessments made by all of the agencies involved. Obviously, this task will require the cooperation of all parties, but the final report should be prepared and issued by the responsible regulatory agency, NMEID.
-c &
Gregory G. Eadie Uranium Recovery Licensing Branch Division of Waste Management cc:
H. May, EPA Region VI W. Stumpf, EPA Region IX F. Galpin, EPA D. Hendricks, EPA, LVF J. Womack, IHS, Gallup, NM K. Kreiss, CDC, Atlanta, GA T. Wolff, EID, Santa Fe, NM H. Tso, Navajo EPC, NM 1648 218