ML20217P139
| ML20217P139 | |
| Person / Time | |
|---|---|
| Issue date: | 04/09/1999 |
| From: | William Ford NRC |
| To: | Robert Carlson NRC |
| Shared Package | |
| ML20217N400 | List:
|
| References | |
| FOIA-99-336 NUDOCS 9910290226 | |
| Download: ML20217P139 (10) | |
Text
} Anne R:mir3z - naturita gw r:vi".w - itsp disposal cell.wpd Page 1 j From:
William Ford ' A ""
To:
, nJ -
Date:
Fri, Apr 9,1999 5:12 PM
Subject:
Groundwater Review - LTSP Upper Burbank Disposal Cell
Dear Bob,
The following is my review of the "Long-Term Surveillance Plan For The Upper Burbank Disposal Cell, Uravan, Colorado" dated February,1999.
Section 2.6 of the plan does not mention the commitment that the DOE has made to establish concentration limits for strontium and tin will be determined by routine sampling of CM 93-1 and CM 93-2 during long-term site surveillance activities. This commitment was made in the latest version of the Remedial Action Plan and should be included in the LTSP.
On page 2-14 of the LTSP the statement is made that " DOE will monitor forpotential seepage from the disposal cell by periodically evaluating water levels in the three monitor well completed at the contact of the Salt Wash and Summerville." It enough wateris available, samples will be taken and analyzed for the primary he:ardous constituents." However, tho LTSP does not provide a minimum frequency for well water level monitoring. The LTSP should specify a minimum frequency of monitoring.
CC:
Richard Weller
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9910290226 991027 PDR FOIA MIDDLET99-336 PDR
l Anne Ramir2z - N5turita LTSP retfiew 07 21-1999.wpd
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Dear Phyllis,
I have completed my review of the Long-Term Suve@:cas Pim Fm 7he Upper Burbank Disposal Cell, Uravan, Colorado dated July 1999. The DOE hars adequately addressed the two groundwater comments from our previous rewn.
Sincerely, William Ford Comment: Section 2.2.6, Page 2-14 On page 2-14 of the LTSP the statement is made that " DOE wiHmonitorforpotential seepage from the disposal cell by periodically evaluating waterlevels in the three monitor well completed at the contact of the Salt Wash and Summende." ~If enough wateris available, samples will be taken and analyzed for the primary hazardous constituents." However, the LTSP does not provide a minimum frequency for well water level monitoring. The LTSP should specify a minimum frequency of monitoring.
Evaluation:
The Long-Term Surveillance Plan has been revised to specify a monitoring frequency. In the 1 paragraph of Section 2.6.2 it now states that *Monitonng will be performed the first, third and fifth years afterlicensing. The need to continue monitoring will be evaluated after the fifth year". Therefore, this comment has been adequately addressed and is closed.
Comment: 2.6.1, Page 2-14 Section 2.6 of the plan does not mention the commitment that the DOE has made to establish concentration limits for strontium and tin will be determined by routine sampling of CM 93-1 and CM 93-2 during long-term site surveillance ac ivities. This commitment was made in the latest version of the Remedial Action Plan and should be included in the LTSP.
Evaluation:
The Long-Term Surveillance Plan has been revised to establish concentration limits for strontium and tin The 1 paragraph of page 2-14 of Section 2.6.1 now states that " DOE will establish concentration limits for strontium and tin by routine sampling of CM 93-1 and CM 93-2 during long-term sur eillance activities." This comment has been adequately addressed and is closed.
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- l Anne Ramirez - N060198a.wpd Page i l NATURITA TER 5.0 WATER RESOURCES PROTECTION 5.1 Introduction The Naturita processing site is located in the San Miguel River Valley and is underlain by unconsolidated alluvial floodplain deposits and fill material. The alluvium is the upper-most aquifer at the processing site and is contaminated from former processing-site activities. The alluvium is underlain by the Brushy Basin and the Salt Wash Members of the Morrison Formation. The Brushy Basin consists of interbedded shale, sandstone, and conglomerate lenses. The Salt Wash consists predominantly of sandstone with some shale. The Brushy Basin and the Salt Wash have not been affected by uranium processing activities. Existing groundwater contamination does not presently represent a risk to human health or the environment.
However, DOE is required to demonstrat t that cleanup or control of existing processing-related groundwater contamination at the Naturita site will comply with the EPA groundwater protection standards in Subpart B of 40 CFR Part 192. Groundwater cleanup at the former processing site will be addressed under a separate DOE program and a National Environmental Policy Act ;..acess; using strategies and options outlined in a programmatic environmentalimpact statement that has been developed for the UMTRA Project. The need for and extent of groundwater cleanup at the Naturita site will be evaluated based on the extent of existing contamination, the potential for current or future groundwater use from the uppermost aquifer, and protection of human health and the environment.
At the Upper Burbank Disposal site, DOE must comply with the final standards issued by the EPA on January 11,1J95 (40 CFR 192.20). From a review of the information submitted; it appears that the site will comply with the requirements of Subpart A of the EPA groundwater protection standards. However, the NRC staff has yet to reach a determination on the long-I term surveillance plan which the DOE has not yet submitted to the NRC.
5.2 Hydrogeologic Characterization 5.2.1 Identification of Hydrogeologic Units l
A.
Processing Site l
t At the Naturita processing site; unconfined groundwater occurs within the alluvial flood plain posits from 3 to 18 ft (0.9 to 5.5 m) below the land surface. The saturated thickness is approximately 15 ft (4.6 m) in the vicinity of the site. The next deepest aquifer at the site is the Salt Wash Member of the Morrison formation, which consists predominantly of sandstone with some shale. The Salt Wash aquifer is separated from the alluvial aquifer by the Brushy Basin j
Member of the Morrison formation. Under the site. the Brushy Basin Memberis considered an a
aquitard and consists of thick, laterally extensive, interbeoded shaies with some sandstones. It ranges in thickness from 110 to 165 ft (33.5 to 50.3 m). The top of the Salt Wash aquifer is approximately 130 to 165 ft (39.6 to 50.3 m) below land surface near the site. The total thickness of the Salt Wash aquifer has not been determined, but is at least 80 ft (24.4 m) thick in the vicinity of the processing site.
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- l Anne RamirGz - N060198a.wpd B.
Disposal Site Five principal hydrostratigraphic units occur within the upper 800 ft (240 m) of sediments beneath the disposal site. From the land surface down, these are: (1) sandstones and shales of the Salt Wash Member of the Morrison Formation; (2) shales and siltstones of the Summerville Formation; (3) sandstone of the Entrada; (4) sandstones of the Kayenta; and (5) sandstones of the Wingate Formation.
The Salt Wash Member directly underlies the disposal site and has a thickness of about 120 ft (37 m). This unit is predominantly comprised of sandstone with some interbedded shale layers. The Summerville Formation underlies the Salt Wash Member. This unit is considered an aquitard and is 90 ft (27 m) thick. It is composed of massive clayey mudstones, silty shales, clayey siltstones, and minor,interbedded sandstones. The Entrada Formation underlies the Summerville Formation and has a thickness of approximately 160 ft (49 m). The Summerville Formation is a sandstone. Underneath the Summerville formation is the Kayenta Formation, f
which has a thickness of approximately 180 ft (95 m). This formation consist of interbedded layers of sandstone, siltstone, shale, and some conglomerate. Below the Kayenta Formation is the Wingate Formation. This formation is about 250 ft (76 m) thick and is a sandstone. The Kayenta Formation together with the Wingate Formation form the first saturated aquifer beneath the disposal site.
Below the Wingate Formation is the Chinle Formation. The Chinle Formation is about 400 ft (120 m) thick and is predominantly a siltstone. Because of it's low permeability, the Chinle Formation acts as an aquitard to vertical groundwater niovement.
5.2.2 Hydraulic and Transport Properties A.
Processing Site The occurrence of shallow groundwater in the alluvial aquifer is limited by the lateral extent of the alluvium in the vicinity of the Naturita processing site. The average hydraulic conductivity for the alluvial aquifer is 3.0 ft/ day (0.001 cm/sec) and the average linear groundwater velocity is 0.06 ft per day (2x104 am/sec). The groundwater flow direction in the alluvium is subparallel (northwest) to the San Miguel River. Groundwater from the alluvial aquifer discharges into the San Miguel River northwest of the site.
The Salt Wash aquifer is a major regional groundwater system in the area. The potential area of natural discharge from the Salt' Wash aquifer is the San Miguel River northwest of the processing site. For the Salt Wash aquifer, hydraulic conductivities averaged 0.06 ft/ day (2x104 cm/sec) and the average linear groundwater velocity is estimated to be 0.002 ft/ day (7x10 cm/sec). The Salt Wash aquifer is separated from the alluvial aquifer by the Brushy 4
Basin Member, which locally is considered an aquitard. Groundwater in the Salt Wash aquifer is confined, and has a potentiometric surface that is higher in elevation than the water tabte in the alluvial aquifer. Therefore, if any significant flow were to occur between the Salt Wash aquifer and the alluvial aquifer, water movement would be upwards from the Salt Wash aquifer through the Brushy Basin Member and into the alluvial aquifer.
B.
Disposal Site
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Page 3J The disposal site is underlain by approximately 600 ft (180 m) of urreurated sandstone, siltstone, and shale. The Summerville Formation, composed of shahe:and siltstone, is about 120 ft (37 m) below the site and has a hydraulic conductivity of len than 0.01 ftlyr (1.0x10-8 cm/sec). This 90 ft (27m) thick layer functions as an aquitard and should prevent any potential groundwater contamination from the disposal site from reaching the Kayenta/Wingate aquifer.
The Kayenta/Wingate Formation is the uppermost aquifer berte.ath the disposal site. Only the Kayenta/Wingate aquifer is saturated beneath the disposal site. The aquifer is unconfined and at a depth of approximately 600 ft (180 m). Average hydraulic conductivity of the Wingate formation is 0.12 ft/ day (4.2x104 cm/sec). Groundwater flow beneath the repository is toward the north at velocity of about 8 ftlyr.
Primary recharge to the Kayenta/Wingate aquifer is northeast of the San Miguel River along the Uncompahgre Plateau. Secondary recharge to the Wingate portion of the aquiferis from the Paradox Valley south of the site. Discharge from the aquifer is to the San Miguel River.
5.2.3 Extent of Contamination A.
Processing Site To determine whether uranium processing activities at the Naturita processing site have influenced groundwater quality in the alluvial aquifer; DOE collected samples from on-site and down gradient monitor wells and analyzed these samples for the constituents listed in Table 1 to Subpart A and Appendix l of 40 CFR Part 192. Based on this analysis; arsenic, cadmium, chromium, fluoride, methylene chloride, molybdenum, selenium, strontium, thallium, tin, toluene, uranium and vanadium, radium-226 and -228, and gross alpha and may be contaminants in the alluvial aquifer groundwater. Of these constituents; arsenic, cadmium, molybdenum, selenium, uranium, radium-226 and -228, and gross alpha were found to exceed the EPA maximum concentration limits. Based on uranium concentrations, a contaminant plume extends at least 1500 ft (460 m) down gradient from the former mill yard and has a maximum width of approximately 900 ft (275 m). Contaminated groundwater from the alluvial aquifer discharges into the San Miguel River. where no impacts on the river water quality have been observed to date.
Groundwater in the Salt Wash aquifer was found to not be contaminated as a result of milling operations at the processing site.
B.
Disposal Site Groundwater at the disposal site is presently uncontaminated by the disposal of contaminated material.
5.2.4 Water Use A.
Processing Site Eight wells are located within 2 miles (3.2 kilometers) of the processing site. Water from these wells are used for domestic purposes. Five of these wells are located up gradient from the processing site (four obtain water from the alluvial aquifer and one from the Salt Wash t
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Page 4 l aquifer). The two remaining wells are located down gradient of the site, but are located on the opposite side of the river. There should be no threat to;up gradientwells from contaminated i
groundwater from the processing site in the allusal aquife.r.as goundaater flow is in the opposite direction from these wells. Groundwater pollution Mhe alWial aquifer should not be 3
a threat to down gradient wells because the river represents a discharge point for the alluvial aquifer. Since, these wells are located on the other side of the rhw.. groundwater contamination in the alluvial aquifer should not reach them.
No impacts have been observed or are expected to groundwater in the Salt Wash aquifer from the processing site. No impacts to surface water quality have been observed from contaminated alluvial groundwater at the site.
Future use of groundwaterin the alluvium for domestic consumption is not expected. The is because the alluvial aquifer has a very low potential for use as a source of water, since it is limited to the small area of alluvium in and adjacent to the San Miguel River. Alternative supplies of reliable, good quality water are available from the town of Naturita, from surface water, and from deeper groundwater aquifers.
B.
Disposal Site Four wells produce groundwater within two miles (3.2 kilometers) of the disposal site. All of these wells are owned by Umetco Minerals Corporation. These wells are no longer being used and will be plugged prior to deeding the land in and around Uravan to the federal government.
Five additional wells are within a radius of five miles from the site. All of these wells are up-gradient of the disposal site and therefore cannot be impacted by the site. Future use of groundwater beneath the Upper Burbank site is limited by the poor water quality and low permeability of the Wingate Formation and significant depth [600 ft (180 m)) to groundwater.
In the future, land will be deeded to the federal government, which will limit the development of groundwater resources by the general public.
There are no agricultural or domestic surface-water users within a 2-mile (3.2-kilometer) radius of the site. Umetco Minerals Corporation does have water rights on the San Miguel River for industrid uses. Within a 5-mile (8-kilometer) radius of the site, water use is limited to springs used for stock water. The closest spring used for stock watering is located about 4 miles (6 kilometers) northeast of the site.
5.3 Conceptual Design Features to Protect Water Resources A.
Processing Site Groundwater contamination does not represent a risk to human health or the environment because there is currently no consumption of the contaminated groundwater in the alluvial aquifer. The distribution of hazardous constituents in groundwater will decrease with time, because contaminated materialis being moved off site to another location and because the alluvial aquifer discharges to the San Miguel River. This means that existing contamination in alluvial aquifer groundwater will eventually be flushed out of the aquifer and diluted by the water in the San Miguel River. Groundwater cleanup at the former processing site will be addressed under a separate DOE program and a National Environmental Policy Act process; using strategies and options outlined in a programmatic environmentalimpact statement that has been developed for the UMTRA Project I
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B.
Disposal Site The climate in the vicinity of the disposal site is semiarid. Under natural conditions deep percolation at the disposal site is less than 0.01 f t /ft /yr and may for all practicable purposes 3 2 be zero. The lack of a perched zone under the disposal site and the lack of springs and seeps along the canyon walls further indicate that the site has a very low infiltration rate. The disposal site was modeled by DOE to determine possible infiltration rates after cover 3 2 construction. Modeling results suggest a very low infiltration rate of about 0.028 f t /ft /yr 3
through the cover. This infiltration rate equates to a flow of approximately 0.1 gpm (9660 ft /yr) through the base of the 8-acre disposal cell. This indicates that very little deep percolation should occur underneath the disposal cell.
Travel time for !iquid from the base of the disposal cell through the Summerville Formation was calculated to be in excess of 1,000 years.
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i The residual radioactive materials that will be disposed of at the site are principally contaminated soils. The contamination of these soils should be relatively low due to the mixing i
of the original tailing s materiais with surficial soils. Batch tests performed on this soil material confirm that this mat 3 rial has relatively low concentrations of radionuclides and heavy metals.
Geochemical attenua bn of any leachate from the disposal site would occur as contaminated water flows through the bedrock formation.
5.4 Disposal and Control of Residual Radioactive Materials 5.4.1 Water Resources Protection Standards For the Disposal Site The groundwater standards (40 CFR 192.02) require three basic elements for setting the groundwater protection standards. These are (1) determination of hazardous constituents; (2) proposal of a concentration limit for each hazardous constituent found to exist in the tailings or leachate; and (3) specification of the point of compliance. The DOE analyzed groundwater samples from the alluvial aquifer beneath the Naturita processing site and conducted laboratory batch teach tests of contaminated soil material from the Natunta processing site.
Based on these tests, DOE identified 25 hazardous water quality parameters that are reasonably expected to be in or derived from residual radioactie material to be disposed of at the site. These parameters were selected to be monitored at the point of compliance and are presented in Table 5-1. For these parameters, the DOE has established concentration limits (Table 5-1). The proposed concentration limits are the either the maximum concentration limit or for those hazardous constituents without maximum concentration limits, the statistical maximum of background groundwater quality derived from water samples collected from Wingate well CM93-1 and CM93-2.
Wingate well CM93-2 is designated as the point of compliance for the disposal site. This well is immediately down gradient of the disposal cell.
f 5.4.2 Performance Assessment for the Disposal Site DOE must demonstrate that the performance of the disposal unit will comply with EPA's groundwater protection standards in 40 CFR 192 Subparts A and C. The disposal cell design
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should minimize and controi releases of hazardous constitants to gnwndwater and surface water to the extent necessary to protecibaman health. The'fulbuing,are important to
, performance of the disposal site:
1.
The uppermost aquifer, the V! ingate Fonnatica fies approximately 600 ft
. (180 m) below the base of the disposalcell ard a hydogeologically isolated from surface recharge or initial transient drahage hva the disposal cell by low permeability shales and mudstones overlying the atni.fer.
2.
The Summerville Formation, the principal aquitard beneath the site, is approximately 90 ft (27 m) thick and effectively isolates groundwater in the underlying Kayenta/Wingate aquifer from potential contaminants in the disposal cell.
3.
Geochemical properties of the bedrock materials attenuate hazardous
. constituents possibly associated with leaching of the residual radioactive materials.
4.
The multi-layered cover reduces the infiltration rate and minimizes long-term seepage from the cell.
5.
.The disposal cell will be contoured to provide efficient drainage of precipitation away from the disposal cell and to minimize excess moisture in the cover and associated infiltration.
5.4.3 Closure Performance Demonstration for the Disposal Site DOE must demonstrate that the proposed disposal design will (1) minimize and control groundwater contamination, (2) minimize the need for further maintenance, and (3) meet initial performance standards of the design,in accordance with the closure performance standards of 40 CFR 192.02. The disposal cell design uses a multi-layered cover to reduce the infiltration rate ud minimize long-term seepage from the cell. The disposal cell will be contoured to provide efficient drainage of precipitation away from the disposal cell and to minimize excess moisture in the cover and associated infiltration. In addition natural stable material will be used in constructing the disposal cell to minimize the need for further maintenance.
5.4.4 Groundwater Monitoring and Corrective Action Plan at the Disposal Site u
The DOE is required by 40 CFR 192.03 to implement groundwater monitoring during the post-l disposal period for the purpose of demonstrating that the disposal cell will perform in accordance with the design. 40 CFR 192.04 requires the implementation of a corrective action l
j program if the monitoring shows an exceecance of concentration limits. The monitoring plan j.
required under 40 CFR 192.03 should be designed to include verification of the site-specific assumptions used to project the disposal system performance. Prevention of groundwater contamination may be assessed by indirect methods, such as measuring the moisture migration within varus components of the cover, tailings, or beneath the tailings; as well as direct groundwater monitoring.
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At the disposal site, DOE will monitor potential repceno y seepage ming wells at the contact of the Salt Wash and Summerville Formations inear the disposalcell for a period of time following l
completion of remedial action. Monitoring any perched grcadser ore the top of the Summerville from the disposal cellincludes we!! BR95-1 BR95-2, and BR95-3. If seepage is detected in these monitor wells, performance monitorirrg of wets CMS 3-1 and CM93-2 will be
> conducted.
5.5 Clean-up and Control of Existing Contamination at the Processing Site The DOE is required to demonstrate that cleanup or control of existing processing-related groundwater contamination at the Naturita site will comply with the EPA groundwater protection standards in Subpart B of 40 CFR Part 192. Groundwater cleanup at the former processing site will be addressed under a separate DOE program and a National Environmental Policy Act process; using strategies and options outlined in a programmatic environmentalimpact statement that has been developed for the UMTRA Project. The need for and extent of groundwater cleanup at the Naturita site will be evaluated based on the extent of existing contamination, the potential for current or future use of groundwater from the uppermost aquifer, and protection of human health and the environment.
5.6 Conclusions The staff concludes that the proposed remedial action for the Naturita sites will acceptably comply with the EPA groundwater standards, with the exception of the following open issues which may be deferred:
1.
DOE must demonstrate compliance with EPA's groundwater clean-up standards
' in 40 CFR 192, Subparts B and C at the Naturita processing site (deferral provided by the UMTRCA amendment of 1982).
2.
DOE must provide the details of its groundwater monitoring program (sampling frequency, etc.) for the disposal site to demonstrate compliance with 40 CFR 192.03. This information can be included when DCE submits the long-term surveillance plan to the NRC for review.
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i Table 51 Hazardous Constituents and Concentration Limits for the Disposal Site Constituent Concentration Limit Aluminum 0.1 mg/L (background)
Antimony 0.1 mg/L (backgrouM)
Arsenic 0.05 mg/L (maxima corn.entration limit)
Barium 1.0 mg/L (maximurs c.oncentration limit)
Beryllium 0.05 mg/L (backgrtvarrft Cadmium 0.01 mg/L (maxinra concentration limit)
Chromium 0.05 mg/L (maximum ctincentration limit) -
Copper 0.02 mg/L (bacn.grour:d)
Cyanide 0.01 mg/L (background)
Fluoride 5.9 mg/L (background)
Gross alpha (excluding uranium and radon) 44.7 pCl/L (background)
Lead 0.05 mg/L (maximum concentration limit)
Mercury 0.002 mg/L (maximum concentration limit)
Molybdenum 0.1 mg/L (maximum concentration limit)
Nickel 0.05 mg/L (background)
Nitrate (as N) 10 mg/L (maximum concentration limit)
Radium-226 and -228 5.0 pCUL (maximum concentration limit)
, Selenium 0.01 mg/L (maximum concentration limit)
, Silver 0.05 mg/L (maximum concentration limit)
Strontium 0.1 mg/L (background)
Thallium 0.01 mg/L (background)
Tin 0.005 mg/L (background)
Uranium 0.044 mg/L (maximum concentration limit)
Vanadium 0.05 mg/L (background)
Zinc 15.5 mg/L (background) o