ML20209H687
| ML20209H687 | |
| Person / Time | |
|---|---|
| Issue date: | 06/27/1986 |
| From: | Justus P NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Knapp M NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| References | |
| REF-WM-58 NUDOCS 8609150313 | |
| Download: ML20209H687 (10) | |
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3 $ 7 96 REBrowning MBell J0 Bunting Malcolm R. Knapp, Acting Chief, WMLU ustus MEMOPANDUM FOR:
Division of Waste Management MWeber & rf Philip S. Justus, Acting Chief, WMGT MFliegel FROM:
Division of Waste Management Ig U
SUBJECT:
REVIEW 0F SHIPROCK RAP MODIFICATION NUMBER 3:
GROUNDWATER CONTAMINATION IN FLOODPLAIN ALLUVIUM In response to TAR number WM-86514, we have reviewed DOE's proposed Modification Number 3 to the Shiprock Revised Final Remedial Action Plan (RAP) relevant to Change Number 13 (Groundwater Contamination in Floodplain Alluvium). On the basis of our review, we have concluded that DOE's proposed modification is inadeouate to resolve NRC's concurrence contingency about the contaninated groundwater in floodplain alluvial sediments northeast of the Shiprock sito. This memorandum discusses the general basis for our conclusion; Enclosure I provides detailed coments on both the proposed action and Appendix E to the Shiprock Processing Site Characterization Report (PSCR). The PSCR sumarizes the data that DOE considered in developing its proposed modification.
Background
When NRC conditionally concurred with the Shiprock RAP in June 1985, NRC expressed concern about potentially contaminated groundwater in the floodplain sediments at the Shiprock site [cf. letter from Higginbotham to Themelis dated June 6, 1985). The city of Shiprock obtained groundwater from these sediments prior to 1968, thus the floodplain sediments are a potential source of drinking water. In response to this concern, DOE initiated a program to characterize the extent and type of groundwater contamination in the floodplain sediments.
After the initial phase of this program indicated groundwater contamination, DOE installed and sampled 25 additional monitoring wells. The results of this sampling program are provided in Appendix E to the PSCR. NRC's interpretation of the results indicates that the groundwater has been contaminated with ,
amonium, fluoride, molybdenum, nitrate, selenium, sulfate, uranium, and vanadium. In addition, DOE interprets the monitoring results as indicating that groundwater on the north side of the San Juan River may have been contaminated by uranium milling activities across the river at the Shiprock site.
DOE's Proposed Modification Recognizing groundwater contamination in the floodplain sediments as a potential problen, DOE proposes in Change Number 13 to include the floodplain within the designated site. By including the floodplain, 00E hopes to WM Record file WM Project 8f D0cket No.-
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WM-58/MFW/86/06/25/SHIPROCK preclude future use of groundwater within the floodplain sediments to prevent human or environmental exposure to contaminants in the groundwater.
Change Number 13 states "The floodplain adjacent to the site will be included in the designated site or access will otherwise be restricted so there can be no use of contaminated ground water from the floodplain alluvium."
WMGT Comments WMGT endorses DOE's 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 systen is avafiable locally for distribution of drinking water.
DOE's proposed modification, however, does not adeouately 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. The inadeouacy of DOE's proposal stems from (1) lack of specific actions in the proposed RAP modification, (2) lack of consideration of the duration of necessary control, and (3) insufficient consideration of the legality of DOE's proposed approach for preventing exposure to contaminated groundwater.
DOE's proposed modification is not detailed enough to allow NRC to verify that the controls will be effective in preventing human or environmental exposure.
The language of the modification does not ecmmit DOE to a particular course of action to restrict access to contaminated groundwater beneath the floodplain.
For example, the phrase "or access will otherwise be restricted" 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 DOE will implement 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.
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WM-58/MFW/86/06/25/SHIPROCK sufficient to determine the termination of water contamination hazards and to confirm that a durable federal, state, tribal or local agency has sufficient authority to enforce the groundwater use restrictions. 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. DOE's proposed modification, however, does not estimate the duration of the groundwater contamination hazard nor rake provisions for monitoring programs sufficient to assess the duration of the hazard. The proposed n.odification 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 DOE's Maintenance and Surveillance Plan for the Shiprock site [ currently under WMGT review].
In addition Section 4 of NRC's SRP requires NRC reviewers to verify that proposed institutional controls enccmpass water contamination that may cause significant adverse impacts. DOE's monitoring program in the floodplain sediments was limited because of flooding when the monitoring wells were installed in August 1985. As a result, DOE has not characterized the extent of groundwater contamination in the floodplain sediments north of wells 601, 624, and 627. Further, 00E has interpreted that groundwater may be contaminated north of the San Juan River based on elevated concentrations of molybdenum and vanadium in wells 631 and 632. DOE has not determined the extent of groundwater contamination in the floodplain sediments north of the Shiprock site across the San Juan River. Consequently, NRC staff cannot verify that DOE's proposed institutional controls encompass water contamination that may cause significant adverse impacts. Institutional centrols are of no value unless a local, state, tribal, or federal agency has the authority to enforce groundwater use restrictions and thus prevent exposure to contaminated groundwater. DOE's proposed modification does not assess whether such authority would exist if it included the floodplain in the designated site. The modification should be amended to assess whether such authority would exist to enforce restrictions of groundwater use and explicitly document the limits of this authority. Ir addition, DOE should consider the need to characterize the extent of groundwater contamination to assure that institutional controls enccmpass water contamination that may cause significant adverse impacts.
The questionable legality of DOE's acquiring the floodplain north of Shiprock site for the purpose of restricting groundwater use is the third maior factor that weakens DOE's proposed modification. WMGT has reviewed the technical (i.e., non-legal) aspects of DOE's proposed institutional controls. Review of
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1 WM-58/MFW/86/06/25/SHIPROCK the legal aspects of DOE's proposal, however, should be referred to ELD. We suggest that ELD's review of the proposal address the questions listed below.
In addition, we suggest that NRC request responses to questions 1 8 from D0E.
- 1. Does DOE have authority under UMTRCA to purchase property and water rights to prevent potential human and environmental exposure to contaminated groundwater?
- 2. If DOE does not have this authority, does the Navajo Nation or the State of New Mexico have authority to purchase and control property to 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 fron beneath the Shiprock site if DOE owned and controlled the floodplain property?
- 6. What legal instruments would be required to establish institutional 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?
- 8. Are institutional controls for groundwater contamination inconsistent with the spirit or provisions of UMTRCA or the EPA standards (40 CFR Part 192, Subparts A and C) regarding the lack of reliance on institutional controls for isolation and stability?
- 9. Can NRC legally approve DOE's proposed rrodification in light of the Tenth Circuit Court's rcnand of EPA's groundwater protection guidance in September 1985 and EPA's current development of new groundwater protection standards?
- 10. Does NRC have the authority under UMTRCA to approve implementation of institutional controls to prohibit use of contamittated groundwater?
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WM.58/MFW/86/06/25/SHIPROCK This review was performed by Michael Weber of my staff. Mr. Weber can work with ELD staff on the questions above regarding the legality of 00E's proposed institutional controls for protection against groundwater contamination.
After ELD completes its review of DOE's proposed modification, we suggest you consider scheduling a meeting with DOE to discuss our concerns about the proposed institutional controls. Please contact Mr. Weber if you have any questions or comments about our review.
ORIGINAL SIGNED BT pt ILIP S. JUSTUS Phi'ip S. Justus, Acting Chief Geotechnical Branch Division of Waste Panacement
Enclosure:
As Stated
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DETAILED WMGT COWENTS ON SHIPROCK RAP MODIFICATION No. 3, CHANGE No. 13 AND APPENDIX E TO THE SHIPROCK PSCR RAP Modification No. 3, Change No. 13
- 1. Consideration of River Flow Rates The proposed change to Section 4.4, Paragraph 6 provides flow rates for the San Joen River at the Shiorock site. Although this information is irportant in assessing potential impacts of groundwater contamination en water cuality in the San Juan Piver, its inclusion in Paragraph 6 is not appropriate. In addition, the preposed modifications to the PAP do not consider the river flow rates in assessing the significance of contaminated groundwater discharge to the San Juan River.
Section 4.4 discusses water evality. in the vicinity of the Shiprock site.
Paragraph 6 specifically discusses groundwater cuality within the floodplain sediments north of the tite. The river flow rates provided in the proposed nodification, however, do not belong in this discussion of grourdwater quality in the ficodplain. Although it is important to indicate water levels at the time cf sarpling, the mean daily discharge rates, minimum mean daily discharce rates, and maan annual discharge rates are of no significance to the discussien of grcundwater quality in the floodplain sediments. Rather this information should be presented in another section that evaluates the potential impacts of contaminated groundwater discharge on water quality in the San Juan River. The RAP, as proposed to be modified, does not describe the results of sect t.n evaluation. The RAP should be modified to assess potential impacts of contaminated groundwater discharoe on water quality in the San Juan River and include pertinent information about river flow rates along with this assessment.
- 2. Contamination Acrcss the River The last line of the first paragraph proposed to be added to the end of paragraph f in Section 4.4 can be interpreted to in. ply that shallow groundwater on the north side of the San Juan River has been certaminated by molybdenum ard venadium. NRC staff considers it utilikely that shallow contaminated groundwater flows under the San Juan P4ver from the floodplain
. sediments on the south side of the river. Nevertheless, it is logical to suspect uranium milling. at Shfprock as a potentiel source. of this contamination sirce vanadium and molybdenum are often associated with grnyndwater contamination from uranium tailings. Ir eddition, the Shiprock mill recovered vanadium as a hyproduct of the uranium m'illing ci.rcuit. The PAP 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.
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- 3. Probability of Future Use The second paragraph of the text 00F proposes to add to the end o' Secticn 4.4 states that the likelihood of future use of groundwater within the floodplain sediments is low bece.use of the availability of a municipal water supply and because of the groundwater's " naturally poor quality." The natural quality of the greurvvater, hcwever, has not been defensibly established.
Appendix E to the Shiprock PSCP states that it is difficult te determine the backgrcurd cuality of groundwater within the floodplain sediments. Wells installed in the sediments hydraulically upgradient of the core of the grourdreter contamination also indicated contaminatiun. As a result, COE essunes that the background quality of greurdwater within the floodplain ves approximately the quality of water in the San Juan River. For exanple, the PSCP essunes that background sulfate concentrations range fron 25 to 1000 mg/l (cf. Figure E 12, Shiprock PSCR). Consequently, backgreurd grcundwater quality in the flectr1rin sed'ments has been very poorly established, if established at all. In addition, comparison o' these assumed ranges of background concentrations ird'c' ate that the background quality of groundwater in the floodplain is better than the quality of other nearby sources of grcurdwater. Therefore, the PAP shculd delete " naturally poor quality" as a reason why potential use of gicurdvater within the floodplain sediments is expected to be low.
- 4. Necessity for Protective Measures The last sentence proposed to be added to Secticn 4.4 states that further neasures for water resources protection are not necessary and cites the absence of " toxic constituents" as a partial ,iustification. This statement is inconsistent with DOE's proposed inclusion of the floodplain in the designated site to prevent future exposure of humans and the environment to the contaminated grcundwater. In addition, the statenent about the absence of toxic constituents is ret consistent with groundwater quality data from the floodplain sediments north of the site. These data irdicate elevated concentrations c' ritrate (up to 100 times the New Mu ico 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 centaninated. groundwater does not contain toxic constituents.
5 Present Contaminati6n The pcposed modification to Paragraph E cf Section E.2.2.2 would indicate that groundwater in the floodplair sedinents is presently being contaminated by seepage along the escarpeent north of the site. In addition, the proposed statement would not be consistent with the prepcsed modification to Section 3.6 that identifies the rerd in the floodplain as an additional source of contamination. If grourdwater in the floodplain sedirerts is presently being
WM-58/f!P<l/EC/06/26/ATT contaminated by seepcge along the escarpment, then DOE should implement appropriate measures to minimize or eliminate this centamination in compliance with the EPA standards in a0 CFR Part 192 Subpart A. The RAP should be revised te state whether contamination is presertly occurring or whether it was primarily caused by past discharges. Ir addition, modifications to Sections E.2.2.2 and 3.6 should be consistent with one another.
- 6. Compliance with the EPA Standards Section D cf CFange Number 13 (oage 2) implies that the proposed modification has no irrpact on compliance of DOE's actions with the EPA standards. This statement is incorrect since DOE proposes to comply with the EPA standards by restricting access to the floodplain to prevent buman and environrertal exposure to groundwater contaminated by uranium milling at Shiprock. In addition, fiRC would not have made resolution of groundwater ,
centamination issue a concurrence item if the resolution had no impact on comp'fance with the EPA standards. The statenent that the proposed ecdification has no impact on compliance with the EPA standards should be revised appropriately.
Corrents on Appendix E, Shiprock PSCR
- 1. Distribution of Monitoring Wells The areal distribution of monitoring wells is inadequate to characterif e the spatial extent of . groundwater contamination in the sediments. Based en the contaminant iso-concentration maps portrayed in figures E.9-14, groundwater contamination' would be expected to extend into floodplain sediments north of the ephemeral channel from well 601 to beycrd well 627. TAC hydrogeologists indicated during discussions with NPC staff that the area to the north of the channel was flooded by the San Juan River when the monitoring wells were installed in August 1985. The flooding precluded installation of monitoring wells north of the channel. DOE should consider the need for installing additional monitoring wells north of the channel to characterize the extent of !
contamination or demonstrate that there is no need for installing additional
. wells.
- 2. Groundwater Flow Figure E.8 illustrates that groundwater flow in the ficodplain sediments generally parallels ficw 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 fren N9000 E9500 to N10000, E9500). Close tc the mouth, however, the water levels are higher than those i r. erVacent floodplain sediments closer to the river. This observation suggests that shallow 1 groundwater. flows through the sediments in Bob Lee Yesh and recharges the alluvial sediments in the floodplain. This recharge may affect the l
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WM-58/MFW/86/06/26/ATT duration and extent of groundwater contanination of the fleedplain sediments, since the recharoe originates from the highly contaminated terrace alluvium beneath the tailings piles and mill site. Alternativelv the recharge may be a result of seepage from an artesian well up the wash lo,bserved by ?!RC staff in Octcber cf 1904) or from discharge from rubbish deposited on the north bank l of the wash. The appendix should be revised to assess whether tbe wash is recharging the preundwater system in the floodplain sediments and to evaluate the significance of such recharge to long-tern contamination of floodplain sediments.
- 3. 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 or to amend the appendix by including water level data collected concurrent with neasurements of river stage.
4 Artesian Conditions Based on the groundomter 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 ficw 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.
Alternatively, the artesian levels could be explained as measurement errors or caused by flooding conditions at the time of water level measurement. The appendix should be revised to include an assessment of the significerce of artesian water levels measured in wells 629, 630, and 633.
- 5. Water Level Measurements and Sampling Table E.2 indicatc - that well(pointi 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 198d. thus indicating the, presence'
. of enough. water in the v:c11 to collect a sample. .If there was enough water in the well to sample, tiere should hav4 been enough to measure a water level.
However, the appendix dnes not provide a water level for well 601. The collection of a satple in 1984 from a well that was dry in 1985 calls into
' question the samplirr and water level measurement techniques applied at Shiprock, specifically whether water levels are routinely measured immediately prict to collection of groundwater quality samples. If water levels are measured after sampling, the water level may not accurately represent head in the well because extraction of the water sample and purged water would perturb
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the static water level. If water levels are reasured on different days than when the water quality samples are collected, then the water quality data may be difficult to interpret because the flow system from which they were sampled is unknown. An approach acceptable to the NRC staff would be to measure water levels in wells immediately before purging and sampling the well. The appendix should be revised to clarify why well 601 was sampled without measuring a water level. In addition, DOE should clarify on a generic basis the relationship between groundwater sampling and measuring water levels.
- 6. Missing Constituer.ts Appendix E presents analytical results for water quality samples collected frcm groundwater within flondplein sediments along the San Juan River. Samples from the monitoring wells (wells 608-6??), 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. Although several of these constituents have been observed in groundwater contaminated by uranium milling, the apperdix dces not justify why these constituents were not analyzed. The appendix should be revised to justify why the constituents were not analyzed or to amend the present dr.ta base Sy collecting new samples and analyzing for the constituents.
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