ML20210P470
| ML20210P470 | |
| Person / Time | |
|---|---|
| Issue date: | 12/04/1986 |
| From: | Martin D NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS) |
| To: | Themelis J ENERGY, DEPT. OF |
| References | |
| REF-WM-42 TAC-64655, NUDOCS 8702130392 | |
| Download: ML20210P470 (17) | |
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John G. Themelis, Project Manager Dccket No,d
-db Uranium Mill Tailings Project Office
.U.S. Department of Energy PDW Albuquerque Operations Office LPCR
~P.O. Box 5400 Dit m Hon:
Albuquerque, NM 87115
Dear Mr. Themelis:
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We have completed our review of the draft Site Surveillance and Maintenance (S&M) Plan for the Burrell Township Vicinity Property (VP). Specific comments are enclosed (Enclosure 1), which address NRC concerns with the S&M Plan, in light of issues discussed in NRC transmittals of June 25, 1986, August 8, 1986, September 15, 1986, and October 22, 1986. We have concluded that the DOE should reconsider the scope and extent of surveillance, maintenance and monitoring activities at the Burrell VP.
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The NRC review included the revised Radiological and Engineering Assessment (REA),
the revised engineering drawings and October 10, 1986 specifications, as well as the S&M Plan, and the following concerns have been identified:
1.
The DOE's decision to invoke supplemental EPA standards, in part, acknowledges the potential for collapse and instability of the uncompacted fill material.
It '- this concern that has lead the NRC staff to request that settlenu conitoring be continued until the settlement plots have indicated a tapering tendency.
2.
The elimination of all ground-water monitoring appears to be
-inadvisable, because of the lack of ground-water characterization at the site. The October 22, 1986 letter to DOE requested information which may resolve this concern. However, DOE's decision should reflect that as future custodian and licensee at Burrell, it is responsible for environmental impacts-from the VP under authorities beyond UMTRCA alone.
If for no other purpose than to defend itself from claims and allegations, DOE should maintain a sound ground-water monitoring program to demonstrate compliance with all appropriate ground-water protection criteria. This-is especially advisable, since DOE is employing no deliberate source reduction strategy for the. fill area as a whole.
3.
Although supplemental standards appear to be applicable, certain aspects of the cleanup and construction should still adhere to good construction practice. Aspects of the Burrell remedial action 8702130392 861204 PDR WASTE WM-42 PDR 0FC :WMLU
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DEC 4 W WM42/GNG/11/03/86 l falling short of such practice include the present discharge ditch to the river, the unfilled depression in the eastern end and the uncertainty of the extent of tailings buried in the uncompacted fill and in the site overall. The last two aspects could deleteriously.
affect the potential for ground-water migration of contamination.
It should be understood that the use of supplemental standards at Burrell acknowledges that the level of protection implied by the primary EPA standards cannot be achieved, albeit for justifiable reasons. With this in mind, both NRC and DOE have acknowledged the need for DOE custody and care under NRC license. The S&M Plan does not provide for an adequate post completion care program, rhich should be specifically geared to potential problems stensning from settlement and ground-water pollution. The S&M Plan should include such monitoring activities which will gauge the progress of ground-water contamination and of settlement with specific attention paid to their synergistic effects upon each other.
Since the NRC factored the review of other documentation and the site visits into the review for the S&M Plan, an additional enclosure addressing aspects of the remedial action itself has also been provided (Enclosure 2).
Giorgio Gnugnoli (y questions regarding this transmittal, please contact Should you have an FTS 427-4788) of my staff.
Sincerely, caIGImas steunyr Dan E. Martin, Section Leader Uranium Recovery Projects Section Low-Level Waste and Uranium Recovery Projects Branch Division of Waste Management Office of Nuclear Material Safety and Safeguards
Enclosures:
1.
NRC Staff Coments on the Burrell S&M Plan 2.
NRC Staff Consnents on the Burrell Remedial Action cc: w/ encl.
R. Sena, DOE /AL J. Garcia, DOE /AL R. Smith, URF0 I
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i ENCLOSURE 1 NRC STAFF CONNENTS ON THE BURRELL' VICINITY PROPERTY DRAFT SURVEILLANCE AND MAINTENANCE PLAN 1-t i
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. GE0 TECHNICAL ENGINEERING REVIEW The staff continues to view the uncertainites associated with this design to be serious and significant.
In light of substantial concerns expressed in the June 25, 1986 and August 8, 1986 transmittals to DOE, the staff is providing the following coments and recomendations.
1.
Section 2.0, Final Site Conditions:
Based on the review of information provided by DOE to date, the NRC staff concluded that monitoring for lateral slope movements would be necessary until the data provides a reasonable level of confidence that long-term stability _
would be ensured. Monitoring details such as types and locations of instruments, required dates of installation, frequency and length of monitoring, etc., need to be established along with corresponding tolerable limits. These details have not been provided in the S&M Plan or any other supporting information. This information is necessary to gauge the integrity of the remedial action construction throughout the S&M phase.
2.
Section 2.3, Displacement Monuments, Page 3:
The S&M Plan should identify information relating to monitoring of displacement monuments such as the frequency measurements, the duration of the monitoring period, the action criteria for initiating maintenance and the required procedures for cover system maintenance. Conditions which can result from significant differential settlements due to the heterogeneous and non-compacted condition of the fill material include:
a) concentrated surface water flows which are greater than those used in the design of the erosion barrier; b) significant quantities of water infiltrating through cracks in the radon barrier resulting in zones of localized saturation in the contaminated fill material. This in turn could result in leaching of contaminants into the ground water, accelerated orgnic decay, a reduction in shear strength, and additional settlement of the landfill material; and c) an increase in radon gas released from the cover system.
The staff recommends that the S&M Plan identify the details discussed above which are associated with the proposed displacement monitoring program. Until it can be demonstrated that settlements resulting from placement of the radon barrier and erosion protection layers and from the long-term decay of organic debris have tapered off, monitoring of displacement monuments should be continued.
3.
Section 3.1, Phase I Inspection, Page 6:
The S&M Plan indicates that Phase I inspections shall be conducted annually and that the initial inspection shall occur in the spring of 1987.
The staff has
3-previously noted that since the existing landfill and contaminated materials are heterogeneous, there is still considerable uncertainty associated with the strength and compression characteristics.of the material. Therefore, inspections should be performed more frequently, particularly during the first several years following construction. The staff recommends that observations of displacement and lateral slope movement monuments be performed monthly for at least the first.6 months following construction.
If the inspections indicate that settlements have tapered off and that the pile settlement has stabilized, then the inspections can be performed at least every 3 months up to the first year following construction and every 6 months thereafter. Upon completion of each inspection, a report of the inspection should be provided to the NRC for review.
4.
Proposed East End Final Grading Addendum:
The NRC staff believes that ponding of water in the depression located at the east end of the site may continue to occur.
If ponding should occur, a localized rise in ground-water can be expected. Saturated soil conditions could develop unstable slopes along the embankments of the river ano the depression.
Ponding of water could be avoided, if the area from the depression to the river is graded so that water would drain into the river. The staff suggests that DOE consider this alternative, or otherwise provide documentation that would assure that this area of the site will remain stable.
5.
Section 2.0, Final Site Conditions:
i The REA identifies that the compacted cover will reduce site infiltration and tend to cause a lowering of the ground water table (Page 33).
However, the staff recognizes other mechanisms that could cause a rise in the ground-water table which, in turn, could affect pile stability.
These mechanisms include the following:
a) flood events that could result in the pile becoming inundated.
Flood waters would likely saturate the landfill material by infiltrating the cover drain system; b) significant quantities of water from concentrated surface water flows infiltrating through settlement cracks in the radon barrier; c) large differential settlements that could interfere with the effective operation of the drain system;
.d) clogging of the drain system by sediments which could be easily transported due to the loose nature of the existing landfill material.
Considerable reliance has been placed on the effective operation of the cover and toe drains to assure the stability of the contaminated materials. There-fore, the staff recommends that instrumentation devices, such as several piezemeters to measure ground-water levels and magnitudes and distributicn of pore pressures, be installed along the face of the embankment to assure the effectiveness of the drain system. The instruments should be read with 4
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. GE0 LOGY /GE0 MORPHOLOGY COMMENT Section 6.2, Contingency Plans The Burrell Raciological and Engineering (Assessment considers as appropriate a
~ horizontal seismic coefficient of 0.05g the same value as applied to design considerations at Canonsburg). These coefficients were derived from USGS and Corp of Engineers risk maps of bedrock accelerations. As such, the NRC finds them adequate and conservative.
In this section of the S&M Plan, DOE proposes contingency inspections and maintenance for the following seismic events (Richterscale):
Magnitude Within 3-4 20 km 4-5 50 km 5+
300 km Again, these are the same criteria adopted for maintenance at Canonsburg.
Based on the conditions existing at the Burrell vicinity property, NRC questions the above criteria for the following reasons: 1) tailin at the land-fill exist in a soft in-place soil condition, and 2) gs materials the bottom of the landfill materials and the foundation soils occur below the water table and may continue to exist under saturated conditions after remedial action. Due to these conditions, the foundation soils may be susceptible to liquefaction and the tailings would then be susceptible to collapse.
Therefore, NRC concludes the contingency inspection plan in the case of seismic j
events near Burrell may not be conservative. DOE needs to provide a rationale for the adoption of these criteria in the-final S&M Plan or propose a more l
conservative surveillance plan.
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GROUNDWATER COMMENTS 1.
Section 4.0, Ground-Water Monitoring Wells:
The DOE recommends no groundwater monitoring at the Burrell vicinity property.
This decision is based, in part, upon recent water quality analyses that show radionuclide concentations already below EPA limits. However, the July 23, 1986 site visit revealed conditions which lead the staff to question these water quality results used in the decision-making.
In particular, the poor condition of wells 8 and 22A undermines the reliability of the resulting data.
The decisions and conclusions based on such information could also be
-questionable. Specifically:
i)
The two wells used are not in the same lithologic unit. There-fore, cenparisons between upgradient and downgradient water quality in both aquifers may be inconclusive.
- 11) NRC staff observed well 22A without a cap and the casing of well 8 cracked below ground level. This well integrity could lead to unreliable water. quality results, iii) No well. construction information for either well has been supplied to NRC staff for review.
Therefore, results from these wells provide little reliability for characterizing existing groundwater contamination.
Furthermore, without l
assurance that well integrity was maintained during previous studies, water l
quality results from that time period may not be reliable.
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Section 4.0, Ground-Water Monitoring Wells:
Although DOE claims that groundwater use_is non-existent downgradient of the disposal site, no determination was made on potential for cross-gradient or upgradient.use by nearby residents.
Because of the relatively low transmitting potential of these aquifers, any agricultural or domestic uses may cause greater drawdown and modifications of ground-water flow directions.
3.
Section 4.0, Ground-Water Monitoring Wells:
Several questions have been raised concerning possible contaminants in the disposal area, other than those directly associated with the tailings material (ORNL,1980; DOE,1983).
In fact, priority pollutant and pesticide anaylses have revealed two priority pollutants and three pesticides, none of which are generally associated with tailings.
Furthermore, remnants of unmarked 55-gallon drums have been detected.- NRC is aware of the legal responsibility DOE has to stabilizing'the tailings material, but because DOE is assuming control of the entire site, it may be prudent to occasionally monitor for hazardous constituents in the event that the Burrell site is blamed as a source of pollution in the future.
4.
Section 4.0, Ground-Water Monitoring Wells:
r Claims that lowering water levels in Ponds C and D, and construction of a low-permeability liner will lower the water table below the tailings have been made without providing the technical bases for NRC to review. As re-stated in a subsequent comment on the REA, NRC staff cannot conclude whether lowering the i
l ponds will have the desired effects of de-watering the tailings. The proximity to a recharge source and the large seasonal fluctuations, inherent to the area and observed in past monitoring, make the possibility of complete de-watering of the tailings unlikely. Therefore, leaching and removal of contaminants may continue.
5.
Section 4.0, Ground-Water Monitoring Wells:
DOE appears to be basing their decision not to monitor groundwater, in part, on laboratory results from six water samples that indicate extreme variability in water quality, apparently caused by pyrite oxidation unrelated to the tailings.
However, the results represent water samples taken on different dates. Two of the results may be based upon water samples taken frem wells with poor integrity (see comment I above).
In any case, the variability in some of the constituents (iron in particular) is so great, that the results appear to be of l
marginal use.
In conversations with the TAC, this variability was not readily explained. Thus, it does not appear that background water quality has been i
adequately established. Because this characterization is important in determining increases in contamination, NRC staff concludes that the extent of ground-water contamination cannot be adequately determined. A baseline water quality characterization needs to be established for comparison purposes during the S&M monitoring phase. DOE should present laboratory results from high integrity wells, completed in the proper strata and located up,down-and
' cross-gradient to the site. The samples should be collected over a reasonable time-span to account for seasonality. The analyses should be complete with
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respect to possible contaminants. The S&M Plan needs to reflect a monitoring protocol which can be relied upon to characterize the impacts of the completed site to the groundwater.
6.
NRC Recommendation:
In summary, NRC concludes that the information presented to date, used to base the decision not to monitor groundwater, may not be sufficiently reliable.
Without a measure of reliability of the past ground-water data collection procedures, the decision not to monitor groundwater is insupportable.
In the October 21, 1986 transmittal, NRC requested this additional information to determine whether past data is reliable in light of concent I above.
In any case, DOE needs to reconsider the advisability of eliminating ground-water monitoring.
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ENCLOSURE 2 NRC STAFF COMMENTS ON THE BURRELL REMEDIAL ACTION
. GE0 TECHNICAL ENGINEERING COMMENT During the July 23, 1986 site visit, the staff recommended to the RAC that DOE should implement an interim monitoring plan which would assure that the integrity of the radon barrier will not be compromised by large differential settlements due to soft zones in the fill. Placement of the erosion protection rock on top of the completed pile should be delayed until the interim monitoring program demonstrates that primary compression has been completed and future projected settlements will be tolerable and not compromise the stability of the remedial action construction. Because timing is a critical factor for both construction completion and for maintaining the fill load prior to final covering, the staff suggests that DOE submit the time-settlement plots with supportive evaluation before placement of the erosion protection rock on top of the pile. 'These plots would need to demonstrate that settlements have tapered off and that future projected settlements will be tolerable so as not to compromise pile stability.
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3-SURFACE WATER AND EROSION PROTECTION COMMENTS 1.
Our review of the proposed plan for the Burrell VP Indicates that no erosion protection will be provided at the outlet of the diversion ditch where it discharges to the Conemaugh River east of the site. We note that
~ the ditch will terminate on a very steep slope as discharges enter the
. river. The NRC staff considers that significant erosion of the steep slope would occur, even for minor flood discharges, and that such a design does not constitute good construction practice. Regardless of the design.
will need constant maintenance; and (prudent to provide a design which (1) standard to be met, it does not seem
- 2) will discharge significant amounts of sediments.into the river, thus possibly violating state standards for sediment and pollutant discharges.
2.
Based on a review of the calculations provided, we note that some care was taken to design a relatively flat ditch slope which would produce non-erosive velocities upstream of the outlet. We therefore suggest that the steep slope at the outlet also be protected from erosion. Riprap similar to that provided on the p.rotected fill would be adequate, and the outlet should be designed to meet at least state standards for surface water discharges of sediments and pollutants.
If riprap were provided, it is possible that the width of the outlet could be reduced.
Other design options include: (1) steepening the ditch slope upstream of the outlet so that the invert at the outlet is approximately at the river level, and (2) providing other types of energy dissipation at the outlet.
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. GROUND-WATER HYDROLOGY COP 9 TENTS
- 1.
Determination of Groundwater Quality:
Several statements made in the REA claim that ground water has not been affected by the tailings material. These conclusions are based on laboratory test results, juoged against criteria listed in 10 CFR 20. Beginning with the June 25, 1986 NRC letter to DOE, many questions have been raised regarding the-accuracy of ground-water data collection and characterization. To date, the NRC has not received sufficient information to confirm conclusions made by DOE-on ground-water quality. Thus, it is not possible to properly evaluate these claims found in the REA, nor is it possible to support decisions on long-term maintenance and surveillance with respect to ground-water. The following are areas of the REA which raise concerns and should be addressed by DOE in the remedial action or in the S&M Plan:
A.
Page 8, paragraph 2
" Based on the results presented... it is con-cluded that the ground-water is not significantly contaminated by radioactive elements". However, the results presented (page 22) indicate Ra-226 and Th-230 could exceed the limits found in DOE's Water Protection Plan, when accounting for error.
Further, the condition of the wells at the time of sampling are unknown; the integrity of some existing monitor wells is questionable (noted in NRC July 23,1986 visit).
To date, DOE has presented _no information or data that assures NRC staff that well integrity was acequate at j
the time of sampling.
8.
Page 8, paragraph 3 - DOE is using laboratory results from composite samples (water sampled from several wells) to determine compliance of standards; these well samples were taken from different lithologic units in different areas of the site. Since background water quality appears to be so variable, composite samples may not be representative of existing conditions when different lithologic units are sampled.
C.
Page 22, paragraph 7 - DOE continues to use NRC standards (10 CFR 20), even though they have proposed their own water protection plan to determine compliance.
Conclusions on water quality should be i
based on DOE's plan.
Several other areas in the REA, that cite NRC standards, should also be reconsidered. This, in turn, may alter several conclusions with respect to compliance of standards.
D.
Page 23, paragraph 2 - Conclusions with respect to water quality are not based on all of the available information. Two non-radiological analyses were perfonned that indicate the presence of the pesticides Endo-sulfan I, Dieldrin and Heptachlor (REA,1985, Appn G), and priority pollutants Bis (2-ethylhexyl)phthalate and Di-n-butyl phthalate (unpublished data). Although NRC is aware of DOE's level of responsibility for Burrell, it is recommended that for protection, from potential liability claims stemming from the disposal site, DOE I
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should consider these constituents in their assessment of water quality.
To summarize, DOE should reassess impacts to ground-water quality in light of additional analytical results and potential inadequacies in water sampling.
Moreover, DOE should utilize their own water protection criteria. Finally, DOE should utilize all the laboratory results whe:1 reconsidering ground-water quality, including infomation on well integrity and completion.
c 2.
Effects of Draining Ponds C and D on Water Table Elevation:
4 During remedial action, DOE plans to drain ponds C and D in an effort to expedite surface and ground-water drainage and to lower the water table to a level below the contaminated material. Although the effluent will drain faster without being routed thrcugh the ponds, it is unknown how effective the action will be in lowering the water table.
During an independent review, by NRC staff, of information supplied in the REA, it does not appear the decrease in water levels will extend uniformally to the northern edge of the disposal area, leaving a portion of the contaminated material in the zone of fluctuations of the water table. This finding is based on the current thickness of the tailings below the water table, the distance from the pond to the northern end of the disposal area, and the-proximity to the recharge source. Although DOE claims in the REA that water levels of ground-water are dependent on pond level, the NRC staff concludes that the level of the pond is at least partially influenced by the" elevation of the water table, because of the regional nature of the hydraulic gradient and steepness of the gradient NW of the tailings near the recharge source. Based on this observation, only the tailings material nearest to the pond will be de-watered, leaving some material in the northern area of the site in a saturated state. This conclusion is based on the assumption that the elevation of the water table, just north of the site, is a function of the-regional recharge rate and will likely remain constant. However, seasonality and regional precipitation patterns may lead to significant changes in the elevation of the water table. Although the gradient may increase to account for the loss in the pond level, the changes in water level will probably-t decrease as the distance from the pond increases. Therefore, a uniform i
decrease in water level should not necessarily be expected.
Furthermore, any changes in the hydrologic cenditions at Burrell, in response to. draining Ponds C and D, will occur slowly; complete equilibration may-take i-several years.
In order to confirm the claim that the tailings will be above the water table throughout the year, the NRC staff needs calculations demonstrating the anticipated drops in water level and that the upgradient extent of the drop will result in de-watering the tailings.
3.-
Page 33, section 4.2.4, Subsurface Drainage:
For remedial action at Burrell, DOE plans to place a low-permeability layer i
above the tailings to reduce infiltration, which they claim will lower the water table elevation and result in less contact between ground-water and 1;
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. contaminated material. Hydrologically, this may not be very effective, because the recharge area upgradient of the site is large compared to the site area.
Thus, only a small percentage of recharge will be cut off.
In fact, from reviewing drawing No. CAN-VP200-10-0011, there appears to be a major source of recharge northwest of the site; this is likely the ridge in that direction, which is observable from available topographic maps.
NRC staff agrees that
. placement of the cover will reduce vadose zone leaching, but cautions DOE that reduction in water levels may be less than anticipated. The DOE should provide calculations that show how much the water table will drcp, or state that the drop in water level is anticipated but unknown. The results should be factored into the ground-water monitoring program.
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RADIOLOGICAL COMMENT
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Additional Radiological Surveying:
Recognizing the additional radioactive contamination recently discovered in the eastern end of the site, the staff recommends that additional limited radiological surveying be performed to determine whether more radiological material may be located elsewhere on the site. The surveying should emphasize the area east of the pile.
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