ML20214N930

Forwards Review of Draft Comparative Analysis of Disposal Site Alternatives Rept for Maybell Site,Per WM-86716. Groundwater,Surface Water & Erosion Protection Should Be Considered Significant Issues

ML20214N930
Person / Time
Issue date:	08/28/1986
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-69 NUDOCS 8609170170
Download: ML20214N930 (7)

Text

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MEMORANDUM F0P:

JGrimm FROM: Philip Justus, Acting Chief WMGT

SUBJECT:

PEVIEW 0F DRAFT COMPARATIVE ANALYSIS OF DISPOSAL SITE ALTERfATIVES REPORT FOR TPE VAYFELL SITE, TICKET LtM-86716 Please find enclosed our review of the Maybell Draft Comparative Analysis of Disposal Site Alternatives Report (draft CADSAR). The draft CADSAR considers stabilization-in-place and relocation to Johnson Pit as two alternatives for recedial action. Contrary to the cpiniens expressed in the draft CADFAR it is the staff's opinion that at this tirce ground water, surface water, and crosion protection should be considered as significant issues at both sites. Further, the data, discussicn, ar d cccclusions regarding crosior. protection criteria for each of the proposed remedial acHer alternatives are inconsistent thrcughcut the dratt CADSAR.

We have revicwed this draft CADSAR in the same spirit as described in the cover letter to Malcolm Knapp cercerring our review of the Slick Peck draft CADSAR (August 1, 1086, WM86/WHF/86/07/29). As expressed in this memo, because of the lirited ar ount of data contained in the draft CADSAR we cannot confirm that either site will nect EPA stencards or verify that key issues are resc1ved.

The rnrpcsc cf our concents is to help identify major issues that must be addressed to obtain NRC concurrence in the Remedial Action Plcr. Prvever, because of the limited inforrution presented within the draft CADSAR the issues identificd raay not be comprehensive. New najor concerns may be identified in reviews of future Maybell docunerts.

Participants in this review vere Terry Johnson and Jonathan Forstron (sur race water), Paul P4rnbia (geochemistry), Joel Grirm (geolcgy), Abou_Bakr Ibrabirr (geophysics), and Willian; Ford (geohydrology). Should you have ary questions please contact me or Willien Ford (74697).

ORIGlHAL SIGNED BY 8609170170 060028 PDR PHluP S. JUSTUS WASTE WM-69 PDR Philip Jcetus, Acting Chief WMGT

Enclosure:

As Stated See previous concurrences 3

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WM69/WHF/86/8/21 COMPARATIVE ANALYSIS OF DISPOSALGE0 TE 1.

Section 3.0 THE UMTRA PROJECT MAYBELL SITESITE Characterization of Sites Pa e5 Characterization of each alt 2.

mines jeopardized and by heap-leach future minin es. facilitiernate site has not consider d e

g at the site. Stabilization of the tailithe neighboring ngs may be Maybell site. Table 3.2 indicates that g round water water table is approximately e 150This conclusion is support d Formation" and "There is eviy the the i

exists three to fourdence feet bel to show that aParkneutfeet below t j

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of radionuclides draft CAOSAR does not app geochemi or ow other cont the tailings with no ralizationrowns sig zone concern. cal data ear to containthat to conclude sufficient groaminants beyond th ground waterground wate However characterization are:Some concerns ththe r contamination is not aund water qua,lity o

1. at may need to be addressed d

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i addressed.The present er and future wat uring use in the

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appears to be a significant aThis is important, because tarea m sandstone, is up to 900quiferfeet i composed largely ofne Browns Park Form

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{ development (uraniumwater use ermore may be in the are,a may incrpages 2-4

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2. milling , oilatand especially true area is immediately gas, this site adjacoal,

, since andThisoil shale)gyease as The sandstonesof acent to the site. uranium mine and attenuative capacity either ithe Browns Park Formation zones.

3.

Radiological contaminants ma n the unsaturated or 4 water after having ssed. been procey be much e ground more mobile in th ground water flow due to theLocal ground water flow tailings site.

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WM69/WHF/86/8/21 GE0 TECHNICAL REVIEW 0F COMPARATIVE ANALYSIS OF DISPOSAL SITE ALTERNATIVES REPORT FOR THE UMTRA PROJECT MAYBELL SITE

1. Section 3.0, Characterization of Sites, Page 5 Characterization of each alternate site has not considered the neighboring mines and heap-leach facilities. Stabilization of the tailings may be jeopardized by future mining at the site.

2. Section 3.1.3, Table 3.2, Page 9 Table 3.2 indicates that ground water conditions are not a concern at the Maybell site. This conclusion is supported by the statements that "The water table is approximately 150 feet below the site in the Browns Park Formation" and "There is evidence to show that a neutralization zone exists three to four feet below the tailings with no significant movement of radionuclides or other contaminants beyond this zone." However, the draft CADSAR does not appear to contain sufficient ground water quality or geochemical data to conclude that ground water contamination is not a concern. Some ground water concerns that may need to be addressed during characterization are:

1. The present and future water use in the area may need to be addressed. This is important, because the Browns Park Formation appears to be a significant aquifer composed largely of sandstone, is up to 900 feet in thickness, and may have 750 feet of saturation (FBDU, pages 2-4 and 2-13). Furthermore, future water use in the area may increase as a result of energy development (uranium, oil and gas, coal, and oil shale). This may be especially true at this site, since a uranium nine and milling area is immediately adjacent to the site.

2. The sandstones of the Browns Park Formation may not offer much attenuative capacity either in the unsaturated or saturated zones.

3. Radiological contaminants may be much more mobile in the ground water after having been processed.

4. Local ground water flow directions may not reflect regional ground water flow due to the existence of open pits around the tailings site.

WM69/WHF/86/8/21

5. It may be difficult to determine background water quality due to past milling and mining activities in the area.

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[ 6. It may be difficult to determine if any ground-water pollution i

associated with the pile is from the pile or from adjacent mining, milling, and heap leaching operations, or both.

7. In order to identify ground water pollution from the pile, post remedial-action monitoring may need more detail than planned, i because of adjacent mining, milling, and heap leaching operations.

3. Section 3.1.3, Table 3.2, Page 9 Table 3.2 of the Maybell draft CAOSAR states that the DOE does not consider ground water conditions to De a " concern" for the I stabilization-in place alternative. The table states that there is a

" neutralization zone" three to four feet below the tailings pile which prevents "significant moverrant" of radionuclides or other contaminants.

DOE does not define " neutralization zone", nor does it include any details concerning this zone in the draft CADSAR. DOE apparently feels that the

, " neutralization zone" will protect the ground water of the Browns Park Formation, an aquifer approximately 900 feet thick consisting primarily of

sandstones interspersed with "some shale and mudstone layers" (Ford Bacon

! and Davis Utah, 1981), which underlies the tailings. However, without additional information concerning the " neutralization zone", the NRC staff cannot assess whether the potential exists for contaminants to move from ,

the reclaimed tailings pile and into the ground water. In the final >

CADSAR, 00E should define " neutralization zone", describe the zone in more

! detail (e.g., thickness, areal extent, mineralogy, grain size, i permeability, etc.) and identify the properties responsible for isolating radionuclides and other contaminants. Since incorporating engineered

, ground water protection (i.e., an impermeable liner) into the remedial

• i action could seriously impact the final cost, DOE should demonstrate early 1 in the evaluation process that the " neutralization zone" will adequately protect the ground water,

4. Section 3.0, Table 3.3, Page 11 This table is inconsistent in stating that geomorphology (erosion in Johnson Wash) is a concern while surface waters in the area are not.

These two issues are one in the same and cannot be treated separately.

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5. Section 3.0, Table 3.3, Page 11 Table 3.3 states that surface water is not a concern for the Johnson Pit disposal alternative. However, we consider this conclusion to be premature because in section 4.2, page 15, it is stated that the pit would be " filled with the tailings and other contaminated materials to above the elevation of the surrounding terrain to provide external drainage away from the stabilized tailings." A conceptual design.which calls for overfilling of the Johnson Pit to provide drainage away from the tailings may also subject them to the erosional forces of surface water flow.

Therefore, surface water is a concern for the Johnson Pit alternative unless further information indicates otherwise.

6. Section 3.0, Table 3.3, Page 11 Table 3.3 states that " prior to backfilling" the ground water table in the Browns Park Formation intersected the bottom of Johnson Pit. This is a potential problem, as ground water may infiltrate the tailings pile from below, providing a mechanism for leaching and transporting contaminants.

To mitigate this problem, 00E will leave "at least 10 feet" of fill in the bottom of the pit to separate the tailings from the groundwater. The concern remains, however, and Table 7.2 (page 23) identifies that the prcximity of ground water to the tailings, particularly during wet periods, is a risk associated with selecting the Johnson Pit alternative.

The cost impact of mitigating this problem is not examined in the draft CAOSAR. The final CADSAR should recognize the potential impacts of mitigating the ground water infiltration problem for the Johnson Pit alternative and explore whether using methods such as allowing more than 10 feet of backfill to remain in the pit (which will reduce the volume of tailings the pit can hold) or constructing a liner are feasible methods of eliminating water infiltration from below.

7. Section 4.1, Stabilization in Place (SIP), Page 14 Regrading of the tailings pile and the erosion protection required for the SIP alternative will need to be discussed in the final CADSAR. Review of the draft CADSAR and the FBOU (1981) report indicate that extensive i regrading of the tailings pile and considerable erosion protection may be  !

required for several reasons:

1. The topographic map and cross section of the tailings pile in the FBOU report (Figs. 2-2, 2-5A) reveal slopes on the E and SE sides of the tailings that are rather steep. (rough l

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WM69/WHF/86/8/21 i

I calculations indicate slopes as steep as Sh:1v at the SE corner.) Erosion on the eastern side of the pile (FB00, p. 2-4)

! is probably directly attributable to the steepness of the slope.

It therefore appears that significant regrading of the pile will be necessary to make these slopes less steep.

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2. Figure 3.1 of the draft CADSAR and Figures 2-2, 2-4; 2-5A, and i 2-5B of the FBOU report depict a channel (or gully) on the i

tailings pile. Construction of a drainage channel directly on the stabilized pile is generally undesirable, because erosion i could occur in the middle of the pile rather than along the

! edges. Therefore, extensive regrading of the tailings pile ,

appears to be necessary to alter the present system of surface drainage.

Examination of aerial photographs and topographic maps indicates 3.

the presence of nearby gullies and erosion features which could potentially impact the site design. Provisions for protection [

, of the stabilized pile against lateral erosion and headcutting I need to be examined to estimate the erosion protection I

requirements associated with the phenomena. l The extent of tailings regrading and erosion protection considered in the

'l draft CADSAR for the SIP alternative needs to be clarified and expanded in the final CADSAR.

8. Section 5.0, SIGNIFICANT ISSUES, Page 16 The draft CADSAR is a preliminary document with no technical information .

on seismology and geophysics. Before making any preliminary technical evaluation on the draft CADSAR, the following points should be addressed: ,

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1. The report cites the existence of faults within 0.25 miles of the tailings. These faults should be characterized fully and

! the risk associated with the faults impact on the site should be

• discussed.

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2. Seismic activities within the vicinity of the site should be addressed and a map showing the locations of the earthquakes should be provided. l

! 3. The report should identify the design acceleration.

4. Table 7.2 should include faults as a risk item.

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j 9. Section 5.1, Flood Studies, Page 16 l This section leaves the impression that flood studies are required only if .

l the SIP option is chosen, and then only to define the rock size required  !

t to armor Johnson's Wash. We conclude that flood studies (PMP and FMF) are i required for both the SIP and Johnson Pit alternatives for two reasons: i i

1. Tables 3.2 and 3.3 list erosion of Johnson's Wash into the '

tailings as a concern for both options. Therefore, the size of l

rock required to armor the piles and/or Johnson's Wash should be  !

' determined from flood studies for both options. j i

R. The size of rock required to armor the diversion system which protects the tailings from surface runoff should be determined l from flood studies. This is obviously important for the SIP  ;

option since the present diversion system has been breached on e the western side (FB00, p. 2-4). The need for such a diversion  ;

i system for the Johnson Pit option is not. addressed in the draft CAOSAR, but aerial photographs indicate one may be required.

i i 10. Section 6.0, Table 6.2, Page 19 The table shows erosion protection costs for the Johnson Pit alternative

! are 50". higher than for the SIP alternative (page 18), This appears to ,

i contradict sections 4.1 and 4.2, Site Conceptual Designs, which specify  ;

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similar volumes of erosion protection materials for each alternative. The i

final CADSAR should justify erosion protection costs in more detail. .

11. Section 7.1, Tabic 7.1, Page 21 This table states, that for the Johnson Pit alternative, "headcutting of '

Johnson's Wash would not affect the site," This appears to be in direct

' conflict with Table 3.3 on page 11, which lists erosion of Johnson's Wash l 1 into the pit as a concern. Based on our review, headcutting and lateral I erosion appear to be potential problems at the Johnson Pit; therefore, Table 7.1 should be amended for consistency.

12. Section 7.1, Table 7.1, Page 21-

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- In the comparison of disposal alternatives, isolction from the bed rock aquifer by Mancos Shale is cited as a positive technical factor for the '

Stabilization-in-Place alternative. However, the draft CADSAR does not i seem to recognize the Browns Park Formation which directly underlies the

! site and may be a significant bedrock aquifer. Credit for this aspect of

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WM69/WHF/86/8/21 the site should not be taken until additional ground water information is obtained.

13. Section 7.2, Table 7.2, Page 23 The table assigns 25% risk to the SIP option based on a potential of erosion protection needs above those anticipated, and no such risk for the Johnson Pit alternate site. The comparison directly contradicts Tables 3.2 and 3.3, which identify Johnson Wash as a threat to geomorphic stability at both sites. This inconsistency should be resolved.

14. Section 7.2, Table 7.2, Page 23 This table contains risk values associated with each alternative.

However, the table contains no reference to methods for the risk assessments. This information should be supplied.

15. Section 8.0, Recommendations, Page 24

~We conclude that a surface water quality investigation should be included as part of the field characterization program. Such an investigation should be made to determine the quality of water upstream from the site, downstream, and draining directly off the tailings pile. This data is necessary to establish background surface water quality and any current contamination of surface water caused by the tailings. It will later be used to assess the effects of the chosen stabilization option on surface water quality as part of the monitoring program. Of particular importance is the effect of runoff from Johnson's Wash on the water quality of Lay Creek and especially the Yampa River, from which at least one farmhouse is known to obtain drinking water (FBDU, p. 2-5). The potential for future surface water use in the downstream areas affected by the tailings should also be addressed.

REFERENCES CITED FBDU, (Ford, Bacon, and Davis, Utah), Engineering Assessment of Inactive Uranium Mill Tallings, Maybell Site, Maybell, Colorado, DOE /UMT-0116, 1981 J