ML20214J380
| ML20214J380 | |
| Person / Time | |
|---|---|
| Issue date: | 11/14/1986 |
| From: | Hawkins E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Begay T ENVIRONMENTAL PROTECTION AGENCY |
| References | |
| REF-WM-73 NUDOCS 8612010280 | |
| Download: ML20214J380 (1) | |
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- DISTRIBUTION N
Docket File WM-73 PDR/DCS'"
DBangart, RIV WM-73/TT0/86/11/14/0 Toisen LLW Branch, WMLU URF0 r/f URF0:TTO WM-73 3geggygg Mr. Tom Begay, Program Manager UMTRA Project Navajo Site Program Environmental Protection Administration '85 fl0V 24 S10 3 P.O. Box 308 Window Rock, Arizona 86515 ,, _
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Dear Mr. Begay:
Enclosed please find two (2) documents
- 1. EA and DRAP comments.
- 2. Preliminary comments on 60 percent design and original coments on DRAP.
Should you have any questions, please contact Mr. Tom Olsen of my staff at (303) 236-2813.
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Sincerely, 1 Edward F. Hawkins, Chief Licensing Branch 1 Uranium Recovery Field Office Region IV
Enclosures:
As stated l
l 8612010280 861114 PDR WASTE
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DATE :86/11/14 :Jj
>, DISTRIBUTION
.. 7J Docket File WM-NJG PDR/DCS 08angart, RIV WM-190/RF8/86/01/24/0 dlBElth.?
T01sen HRose PGarcia FE8 261986 URF0:RF8 EHawkins )
Docket No. WM-190 KHargis NM l 040WMt90101E URF0 r/f i 13 John G. Themelis, Project Manager U.S. Department of Energy
' Albuqueruqe Operations Office
.P.O. Box 5400 Albuquerspe, New Mexico 87115
Dear Mr. Themelis:
e
% Staff mytew of the Draft Remedial Action Plan and working document Environmental Assessment for Tuba City have been completed. As we agreed, our review consisted of a broad overview of the documents looking for " fatal flaws " unaddressed areas and sufficiency of basic data and information. To sumarize the enclosed coments, there appeared to be no
! major problems with the proposed remedial action. The coments tend to address more specific technical questions and issues that should not drastically affect the overall plan. At this point, there does not seem to be much value in meeting to go over these comments. If you feel that a meeting would be beneficial, please let us know. However, we should plan to meet when more detailed designs are submitted for review.
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Should you have any coments or questions, please contact Mr. Randy Brich of my staff on FTS 776-2811.
.. Sincerely,
!Ts Orsesaml Etsmc Or NwYrd F. Hawkie Edward F. Hawkins, Chief Licensing Branch 1 Uranium Recovery Field Office Region IV
Enclosure:
As stated cc: F. Bosiljevac, DOE B. Mason, TAC kh Y^$Y UC : A
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I NRC COMMENTS ON DRAFT REMEDIAL ACTION PLAN AND WORKING DOCUMENT ENVIRONMENTAL ASSESSMENT FOR TUBA CITY UMTRA PROJECT Radon Barrier - DRAP
- 1. Page 19. Table 3.2
- a. The average Ra-226 concentration for the total windblown contaminated soils is shown as 33.8 pCi/g. However, Page 18, last sentence of Section 3.2.3 states that the average Ra-226 concentration for the windblown areas is 55.5 pCi/g. Please
'y clarify this apparent discrepancy and provide the bases for the
- correct value.
- 2. Page 8-33, Table 3.5.1 - Please state the order for the tailings layers when calculating required local cover thickness.
- 3. Pages B-35 and B-55, Sections B.5.7 and B.5.13, respectively, refers the reader to Section B.5 for long-term moisture calculations.
Review of Section B.5 does not reveal the referenced calculations.
Accordingly, please provide the necessary information.
( 4. Page 0-25. Section D.2.2.4 - Emergency spill ponds - The text states that no Th-230 analyses were perfonned on soil samples obtained from the emergency spill pond. Therefore, it is impossible to determine if Th-230 is a problem in these areas. Note that on Page 36 of 7
Addendum Dl, BFEC states that equivalent-thorium concentrations are
. high in several soil samples from the evaporation ponds.
- 5. Since characterization of the Th-230 concentration in the upper contaminated layer for the Collins Ranch disposal site has been conducted and Th-230 concentrations were considered for Canonsburg, presumably under Section 40 CFR 192.21(f), please provide your rationale for not conducting similar measurements for this site.
- Surface Water Hydrology and Erosion Protection - DRAP Appendix B. Section B.8
- 1. Provide the bases for the design of the energy dissipation structures that will be constructed at the oitch outlets.
Information should be provided regarding the design bases that will be used to determine:
- a. riprap size. especially with regard to turbulence and velocities in energy dissipation structures, and 1
- b. exit velocities, especially with regard to the ability of natural soils to withstand velocities produced at the downstream end of the structure.
- 2. Recognizing that the rock source may not yet be detennined, information should, however, be provided to document the proposed durability specifications that the rock will meet and the measures
- that will be taken to oversize the rock if the proposed durability specifications cannot be met.
Ground Water - DRAP e.y Page D-232
- 1. Please state what monitoring wells were utilized to establish the extent of vertical contamination in the vicinity and down gradient of the (process mill) site.
- 2. Areas of extensive vertical contamination at and/or below monitoring well screened intervals should be shown in map view and explained in greater detail in order to accurately delineate the plume.
. 3. Also, since vertical contamination is suggested, it is possible that 3 monitoring has not detected maximum plume migration in a down i gradient direction due to shallow depth of screened intervals for
- monitoring well. Accordingly, please clarify the extent of vertical I contamination.
, Ground Water - EA l
Page 43 t
It is not clear whether the estimation of contaminant plume migration (present) is based on monitoring well detection or interpretation of data. If monitoring wells were used to determine plume migration distance, they should be identified with further explanation and map location shown.
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i NRC SUPPLEMENTAL COMMENTS ON !' ,
ORAP FOR TUBA CITY.!,MTRA PROJECT
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- 1. Page 18, Section 3.2.3, last paragraph, second Gentence - Highway 64 is not marked on Figure 3.3. Please clarify the location of,the area discussed.
- 2. Page 18. Table 3.1 5
- a. The total on-pile average radium-226 concentration of
. 862.3 pCi/g appears to be in error when sne performs de '
Y., volume-weighted calculation for the pile's' and subpiles.
[(689,226c.y.)(959.2pC1/g)'+(92,100c.y.)(26.5pci/g)]+
781,326 c.y. = 849.3 pC1/g 1
- b. The total on-pile volume (piles plus' subpiles) is 7bl,32 Sic.y.,
not 781,339 c.y. as shown. ;
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- 3. Page 44, Section 4.4.4. .second paragraph, third sentence: ,
,, How will the rock cover increaseithe long-term sail moisture content
's of the radon barrier cover? Please cite a reference '
which supports this statement. f s
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.' DISTRIBUTION Docket. File WM-73 PoR/Dc5 08angart RIV E 73/TT0/86/10/08/0 Misesh
. _1- R8 rich RGonzales SGrace OCT 16 586 EHaukins KHargis, NM ELW Branch WMLU DGillen, WMLU URFO:TTO URF0 r/f Docket No. E 73 040lM73110E
' John G. Theme 11s Pmject Manager U.~S. Department of Enery Albuquenque Operations office P.O. Box 5400
%g Albuquerque New Mexico 87115
Dear Mr. Themelis:
Staff review of the Draft Remedial Action Plan (DRAP) responses to NRC comments and preliminary design for Tuba City have been completed. As we agreed, our review was conducted on all available data pertaining to the DRAP and Preliminary Design, as per Octobir 6, 1986 meeting between DOE and URF0 staff held in Denver, Colorado. DOE stated that the final design will be forthcoming in 2 to 3 weeks.
kw NRC comments pertinent to the final design documents will be ' issued upon review completion.
Should you have any comments or que'stions, please contact Mr. Tom Olsen of agr staff on FTS 776 2813.
N:. '
- Sincerely,
[5 '
Edward F. Hawkins, Chief .
, Licensing Branch 1 Uranium Recovery Field Office Region IV ,
Enclosure:
Comments !
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4XtE:86/10/10 : /h/(_/fg : : : : :
Tuba City UMTRA Pmject Comments on DRAP and Preliminary Design Ground Water
- 1. We understnad that the ground-water study for the site has been revised based on additional information and analyses. Please provide the details of this study.
Comments: Volume III Supplement to Preliminary Design.
s Comments on Volume III Supplement I. Calc. No. 18-839-21-00, "Es6ankment Design - Toe Drains - Design"
- 1. Sheet 4: In your conclusions on sheet 4, you state that a minimum freeboard of 0.60 ft. is maintained in toe ditch #1, and that this is adequate under PMF conditions. The cross-section for station 18+00, shown on sheet 15, shows a difference of 1.5 ft. (5063.5-5062.0) between the top and bottom of the ditch. The water depth at this station is 1.1 ft.; therefore, the minimum fmeboard is only 0.4 ft.
Accumulation of silt and debris in the channels will probably reduce this freeboard. In addition, since the flow in the ditch goes fmm subcritical to supercritical at about station l 18+00, the water surface wil.1 show undulations which will increase the water depth and further reduce the freeborad. You
.:n should therefore provide assurance that all the ditches have an
- 4 adequate amount of freeboard. We note that for the interceptor ditches, you have a minimum freeboard of 2 feet.
- 2. Sheet 5: You state that toe ditch #1 will discharge into a
- natural waterway with an exit velocity of 4.4 fps. However.
l sheet 4 shows an exit velocity of 4.8 fps. Please correct this apparent discrepancy.
- 3. Sheet 5: You state that rock toes are provided to prevent erosion as per the Arg Corps of Engineers EM 1110-2-1601.
- This EM reconmends rock toe depths of 3 to 5 ft.; however, on
! sheet 18, you show a toe depth of only 2 feet. Since the exit velocity from ditch I will be either 4.4 or 4.8 fps (see conments No. 2 above), which is high enough to erode the fine soils found at the site, the rock toe should be 3-5 feet as reconmended in EM 1110-7-1601.
l 4 You divided toe ditches I and 2 into several reaches and
' calculated rnedian riprap rock diameters (050) for each reach.
Which 050 will be used for riprap design? Substantiate the
. selected rock size.
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- 5. Sheet 15: On the station 10+00 cross-section, you show a ditch sideslope of SV to 1H. This should be corrected to IV to SH.
II. Calc. No. 18-828-05-00, " Permanent Site Drainage - Design Flow Rate on East Side of Pile"
- 1. Sheet 22: Discuss how the infiltration values, used to calculate PMP runoff on sheet 22, were derived. Do these values represent on-site soil conditions? Substantiate your assumptions.
III. Calc. No. 18-828-07-00, " Site Grading rnd Drainage - Interceptor
, Ditches" x
- 1. Sheet 3: On sheet 3, you state... "The flow velocity (and flow depth) is estimated using Mannings equation." Mannings equation is applicable where uniform flow conditions exist.
Since the channel bottom slopes and dimensions of the ditches vary from the upstream to the downstream ends, uniform flow conditions do not exist and the use of Mannings equation may not be conservative. Water surface profiles should therefore be calculated using a method which solves the dynamic equation of gradually varied flow. (the Corps of Engineers HEC-2 f",, computer program is one acceptable method) unless 90u can
" demonstrate that the use of Phnnings equation results in more conservative estimates.of, fl.ow velocities and depths.
- f. The following comments were discussed with the RAC in a telephone j y conversation, and additional information has already been provided.
IV. Calc. No. 18-828-05, "Perwanent Site Drainage - Design Flow Rate on East Side of Pile"
- 1. Sheet 7A: A plot of accumulated PMP verses time shows the PHP emount at time zero as being equal to 4.5 inches. This is not l
correct; the PMP at time zero should be zero. Also, the PMP-time relationship is not linear and should therefore be
. plotted on logarithmic coordinates.
- 2. Sheet 7A: The maximum 10-minute PHP is given as 5.5 inches.
Pcwever, the incremental PMP values used to calculate PMF hydrographs show a maximum 10-minute PMP of 4.3 inches (see sheets 7, 21, 22 and 24). Explain why the maximum PMP value used to calculate hydrographs was not 5.5 inches. Using 5.5 inches instead of 4.3 inches would result in a high PMF 7
peak discharge. Also, explain how the rainfall . values shown on l
sheet 7 were derived from the data on sheet 7A.
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- 3. Sheet 22: On sheet 22, you have tabulated the ordinates of an instant and a final hydrograph. The volumes of these hydrographs are equal, but the peaks am significantly different. Discuss how these two hydrographs are related and what each represents. It appears to us that the PMF peak you calculated (2564 cfs) is too low. The basis for this is that we calculated PMFs using several different approaches and in all cases, the PMF peaks were greater than 2564 cfs. Peaks calculated by the staff were as follows:
Rational method using "C" = 1 4120 cfs SCS method assuming no infiltration 4060 cfs
-< SCS method using a CH = 90 3720 cfs 5' SCS method using a CN = 80 3160 cfs SCS method using your runoff values fra sheet 22 3425 cfs l
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