ML20209D854
| ML20209D854 | |
| Person / Time | |
|---|---|
| Issue date: | 08/08/1986 |
| From: | Knapp M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Themelis J ENERGY, DEPT. OF |
| References | |
| REF-WM-58 NUDOCS 8609090473 | |
| Download: ML20209D854 (7) | |
Text
.
AUG 8 SE DMG/86/07/08 John G. Themelis, Project Manager Distribution:
UMTRA Project Office WM r/f V DM Gillen U.S. Department of Energy WMLU r/f M Fliegel Post Office Box 5400 NMSS s/f M Weber Albuquerque, New Mexico 87115 JO Bunting GN Gnugnoli MJ Bell EF Hawking
Dear Mr. Themelis:
RE Browning DE Martin MR Knapp We have reviewed Modification No. 3 to the Shiprock, New Mexico, Remedial Action Plan, transmitted to us by your letter dated May 29, 1986.
The modification deals with the three remaining conditional concurrence issues, i.e. groundwater in the floodplain alluvium, radon barrier thickness, and seismic stability.
Based on the staff's review of the textual changes to the RAP and the detailed calculations and design pertinent to Change No. 14-Radon Barrier Thickness, we conclude that this change is acceptable and closes the Shiprock radon barrier conditional concurrence issue.
Likewise, based on our review, we find that the proposed RAP changes presented in Change No. 15 - Seismic Stability of Embankment are acceptable and close the seismotectonic characterization conditional concurrence issue.
However, the staff's review of Change No. 13 has resulted in a conclusion that the proposed modification is inadequate to resolve NRC's concurrence contingency about the contaminated groundwater in floodplain alluvial sediments northeast of the Shiprock site.
Enclosed are major and detailed comments on both the proposed action and Appendix E to the Shiprock Processing Site Characterization Report, and questions pertinent to the legal aspects of DOE's proposal.
Should you have any questions regarding this matter, please contact Dan Gillen of my staff at FTS 427-4160.
'#M Record fue WM PmicctM c
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Malcolm R. Knapp, Chief pga /
low-Level Waste and Uranium tpg Recovery Projects Branch
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Division of Waste Management Office of Nuclear Material Safety Meiurn~ to WM. 6N M) ~ ~ ~
.i. __ _i and Safeguards
Enclosure:
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F ENCLOSURE i
REVIEW 0F SHIPROCK RAP MODIFICATION NO. 3, CHANGE N0.13 AND APPENDIX E TO THE SHIPROCK PSCR We endorse consideration of institutional controls, such as land use restrictions, to prevent human or environmental exposure to groundwater contaminated by uranium milling activities at UMTRAP sites.
Implementation of institutional controls at the Shiprock site appears favorable because access to the contaminated area is limited by a natural cliff, the San Juan River, and one dirt road through the restricted Shiprock site; the floodplain sediments have been deposited in the current geomorphic setting and will probably be eroded in the next tens to hundreds of years; and a public water system is available locally for distribution of drinking water.
The proposed modification, however, does not adequately address how the proposed institutional controls will be effective in preventing human and environmental exposure.
Under Section 4 of NRC's Standard Review Plan for RAP's, NRC must verify that proposed institutional controls will prevent exposure of human and environmental populations to contaminants.
Problems with the current proposal include (1) lack of specific actions in the proposed RAP modification, (2) lack of consideration of the duration of the necessary control, (3) insufficient demonstration that the institutional controls fully encompass all contaminated groundwater that may pose potential hazards to humans and the environment, and (4) insufficient consideration of the legality of the proposed approach for preventing exposure to contaminated groundwater.
Major Comments 1.
The language of the modification does not specify any particular course of action to restrict access to contaminated groundwater beneath the floodplain.
This precludes an. NRC finding that the proposed institutional controls will be effective in preventing exposure to the contaminants.
The RAP modification should be amended to specify the measures that will be implemented to prevent human or environmental exposure to the contaminated groundwater.
These measures could include documentation such as a deed notice about the groundwater contamination, deed notice prohibiting use of the groundwater, specific monitoring and enforcement provisions for the restriction, and letters of agreement from the Navajo Nation, the State of New Mexico, and other interested parties.
. 2.
Section 4 of NRC's SRP requires NRC staff to verify that proposed institutional controls are accompanied by provisions for monitoring programs sufficient to cetermine the termination of water contamination hazards.
Unlike the perpetual custody needed for the stabilized uranium tailings, NRC expects that institutional controls for groundwater contamination may be terminated in the future because the contamination should dissipate with time.
Institutional controls for contaminated groundwater may be terminated after contaminant concentrations no longer pose a significant hazard to humans or the environment.
The proposed modification, however, does not estimate the duration of the groundwater contamination hazard nor make provisions for monitoring programs sufficient to assess the duration of the hazard.
The proposed modification should be revised to assess realistic ranges in the duration of the contamination hazard and to provide for monitoring programs to determine when the hazard has dissipated.
The details of the monitoring programs, however, should be included in the Maintenance and Surveillance Plan for the Shiprock site.
3.
Section 4 of NRC's SRP requires NRC reviewers to verify that proposed institutional controls encompass water contamination that may cause significant adverse impacts.
The last line of the first paragraph p'roposed to be added to the end of paragraph 6 in Section 4.4 can be interpreted to imply that shallow groundwater on the north side of the San Juan River has been contaminated by molybdenum and vanadium.
NRC staff considers it unlikely that shallow contaminated groundwater flows under the San Juan River from the floodplain sediments on the south side of the river.
Nevertheless, it is logical to suspect uranium milling at Shiprock as a potential source of this contamination since vanadium and molybdenum are often associated with groundwater contamination from uranium tailings.
The RAP should be modified to assess whether uranium milling has contaminated shallow groundwater on the north side of the San Juan River across from the Shiprock site, and if so, to what extent.
In addition, because of flooding when the monitoring wells were installed, the extent of contamination in the floodplain sediments between the river and wells 601, 624 and 627 has not been characterized.
The RAP should be modified to provide information related to these areas that adequately demonstrates that proposed institutional controls encompass the extent of contamination.
Quest. ions on Legal Aspects 1.
Does DOE have authority under UMTRCA to purchase property and water rights to prevent potential human and environmental exposure to contaminated groundwater?
~ _ _ _ _. _ -
L i-2.
If D0E does not have this authority, does the Navajo Nation or the State of New Mexico have authority to purchase and control property to j
prevent human and environmental exposure to groundwater contaminants?
3.
What groundwater doctrine governs the allocation of tributary and non-tributary groundwater in the vicinity of the Shiprock site?
4.
Is DOE's purchase and inclusion of the floodplain in the designated site consistent with the groundwater allocation doctrine for the Shiprock area?
5.
Could a person use contaminated groundwater from beneath the Shiprock j
site if DOE owned and controlled the floodplain property?
6.
What legal instruments would be required to establish institutional i
controls at the Shiprock site to prevent exposure of humans or the environment to contaminated groundwater?
7.
What enforcement authorities exist to enforce a groundwater use prohibition at the Shiprock site? How effectively'are these authorities likely to be enforced?
Detailed Comments i
RAP Modification No. 3, Change No. 13 i
i 1.
Potential Impacts on Surface Water Quality i
The RAP, as proposed to be modified, does not evaluate the potential impacts of i
contaminated groundwater discharge on water quality in the San Juan River.
This evaluation should be included in the RAP modification and should consider
]
river flow rate data presented in the proposed change to Section 4.4.
2.
Probability of Future Use z-l The second paragraph of the text to be added to the end of Section 4.4 states that the likelihood of future use of grourdwater within the floodplain sediments is low because of the availability of a municipal water supply and because of the groundwater's " naturally poor quality." The natural quality of the groundwater, however, has not been reliably established.
Appendix E to the I
Shiprock PSCR states that it is difficult to determine the background quality of groundwater within the floedplain sediments. Wells installed in the sediments hydraulically upgradient of the core of the groundwater contamination i
also indicated contamination.
As a result, DOE has had to assume that the I
l 4
I i
..a
. A background quality of groundwater within the floodplain is approximately the quality of water in the San Juan River.
Consequently, background groundwater quality in the floodplain sediments has been very poorly established, if established at all.
In addition, comparison of these assumed ranges of background concentrations indicate that the background quality of groundwater in the floodplain is better than the quality of other nearby sources of groundwater.
Therefore, the RAP should delete " naturally poor quality" as a reason why potential use of groundwater within the floodplain sediments is expected to be low.
3.
Necessity for Protective Measures The last sentence proposed to be added to Section 4.4 states that further measures for water resources protection are not necessary and cites the absence of " toxic constituents" as a partial justification.
This statement is inaccurate since the proposed inclusion of the floodplain in the designated site to prevent future exposure of humans and the environment to the contaminated groundwater is considered a protection measure.
In addition, the
' statement about the absence of toxic constituents is not consistent with groundwater quality data from the floodplain sediments north of the site.
These data indicate elevated concentrations of nitrate (up to 100 times the New Mexico State drinking water standard), fluoride (up to 7 times New Mexico standards), and uranium (not exceeding New Mexico's standard but up to more than 100 times EPA's advisory level for drinking water).
The RAP should be modified to remove the statement that protective measures for water resources are not necessary and that contaminated groundwater does not contain toxic constituents.
4.
Present Contamination The pi @osed modification to Paragraph 6 of Section E.2.2.2 indicates that the source of contamination of groundwater in the floodplain sediments is existing seepage along the escarpment north of the site.
The RAP should be revised to state whether contamination is presently occurring or whether it was primarily caused by past discharges.
In addition, modifications to Sections E.2.2.2 and 3.6 should be consistent with one another with respect to the source (s) of groundwater contamination.
t.
Comments on Appendix E, Shiprock PSCR 1.
Groundwater Flow Figure E.8 illustrates that groundwater flow in the floodplain sediments generally parallels flow directions in the San Juan River, but does not provide water level contours near the mouth of Bob Lee Wash (i.e., the ephemeral channel from N9000, E9500 to N10000, E9500).
Close to the mouth, however, the water levels are higher than those in adjacent floodplain sediments closer to the river.
This observation suggests that shallow groundwater flows through the sediments in Bob Lee Wash and recharges the alluvial sediments in the floodplain.
This recharge may affect the duration and extent of groundwater contamination of the floodplain sediments, since the recharge originates from the highly contaminated terrace alluvium beneath the tailings piles and mill site.
The appendix should be revised to assess whether the wash is recharging the groundwater system in the floodplain sediments and to evaluate the significance of such recharge to long-term contamination of floodplain sediments.
2.
River Stage Because of the proximity of the shallow groundwater system in the floodplain sediments to the San Juan River, groundwater flow in this system is expected to be highly transient in response to changes in river stages.
The appendix does not provide river stages measured at the time when water levels were measured in the floodplain sediments in October and December of 1985.
The appendix should be revised to provide such measurements if available, and future sampling should include concurrent river stage measurements.
3.
Artesian Conditions Based on the groundwater levels provided in Table E.2, it appears that wells 629, 630, and 633 are weakly artesian.
The appendix, however, does not discuss the validity or significance of the artesian water levels in the context of vertical flow within the alluvial sediments.
The artesian levels may indicate vertical upward flow from the Mancos Shale into the floodplain alluvium, indicating that this area is a regional or local discharge zone.
The appendix should be revised to include an assessment of the significance of artesian water levels measured in these wells.
1
. 4.
Water Level Measurements and Sampling Table E.2 indicates that well(point) 601 was dry when water levels were measured on December 19, 1985.
Table E.3 lists the analytical results from a sample collected in well 601 in October of 1984, thus indicating the presence of enough water in the well to collect a sample.
If there was enough water in the well to sample, there should have been enough to' measure a water level.
However, the appendix does not provide a water level for well 601.
The appendix should be revised to clarify why well 601 was sampled without measuring a water level.
5.
Missing Constituents Appendix E presents analytical results for water quality samples collected from groundwater within floodplain sediments along the San Juan River.
Samples from the monitoring wells (wells 608-632), however, were not analyzed for concentrations of aluminum, antimony, arsenic, barium, chromium, cobalt, lead, mercury, nickel, organic carbon, lead-210, phosphate, polonium-210, radium-226, silica, silver, strontium, and thorium-230.
The appendix should be revised to explain why these constituents were not analyzed for at least initial characterization of groundwater quality.