ML20203E715

Forwards Branch Comments on West Valley Environ Assessment Rept.Onsite Storage Alternative for Time Period Specified Should Be Given More Consideration Based on Listed Reasons

ML20203E715
Person / Time
Site:	02700043
Issue date:	04/10/1986
From:	Beratan L NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
To:	Theresa Clark NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
NUDOCS 8604240344
Download: ML20203E715 (16)

Text

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i APR 101986 I [ES Filen

fcject ilu 20. -

MEMORANDUM FOR: Thomas Clark -

Advanced Fuel and Spent Fuel i -

Licensing Branch .o. .

Division of Fuel cycle and :d-Material Safety, NMSS ,

FROM: Leon L. Beratan, Chief - - -

Earth Sciences Branch i

^ 20 -

Division of Radiation Programs- ~ ' '

• and Earth Sciences, RES -

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SUBJECT:

WEST VALLEY ENVIRONMENTAL ASSE$6 MENT - -

We have reviewed the draft West Valley Environmental Assessment report which you distributed. Attached are our comments. The comments were provided by the members of the Earth Sciences Branch. Any questions concerning these comments should be addressed to:

l Thomas J. Nicholson, Hydrology (extension 74039)

Jacob Philip, Geotechnical (extension 74604)

Richard McMullen, Geology (extension 74318) l Leon L. Beratan, Chief Earth Sciences Branch sion of Radadon hograms e604240344 860410 DR ADOCK O270 3 and Earth Sciences, RES

Enclosure:

Comments Distribution /R-2811:

/Chron RMinogue Econti RMcMullen PDR Dross LBeratan JPhilip B Sbj/Rd XGoller (26nAMurphy RKornasiewicz ESB:RES:mb ESB:RES ESB:RES ESB:RES:gK ESB:RES )  % j' h TNichplson JPhilip [ RMcMullen RKornasiewicz AMurphy ESB:REgLBeratan 3/p/86 a/25/86 3 /2i/86 4/4 /86 Oy/a7 /86 /l0/86 4

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GENERAL COMMENT

S ON DOE'S EA WITH RESPECT TO HYDROLOGIC ASPECTS

1. The on-site storage alternative for a given period of time (e.g., 5 years) should be given more consideration since (a) there is a lack of experience with the tumulus methodology; (b) there is lack of experience with " success-ful" trench methodology; and (c) there is a lack of ground-water and surfi-cial erosional data base for the site (a minimum of 2 year background surveillance).

2. The leaching rate for less than saturated conditions (i.e., high moisture contents) that would provide sufficient leaching to equal the overall radionuclide release performance of the tumulus for comparison to the trenches should be provided for the lifetime of the waste facility. The moisture content versus leaching curves for the tumulus need to be provided i and the design basis characteristics curves for the engineered layers with  !

time need to be provided.

3. The below ground options and failure scenarios for the trenches are highly restrictive and limited. Other alternatives which would provide for ,

longer pathways and travel times (i.e. , different burial geometries and '

locations) need to be considered and discussed.

4. Insufficient site characterization and baseline data prevent a fair com- l parison of alternatives for both the trench and tumulus options. j i

5. Failure scenarios to be assessed for the tumulus should include " clogging" of the toe drain and local saturated conditions in the base of the tumulus that would allow a high leach rate for the entombed waste.

6. Stability of the trench, both for cap settlement and waste subsidence, needs closer attention.

7. Differential settlement of the tumulus layers needs closer attention.

8. A detailed analysis of local intense rainfall events for both the tumulus and trenches for analyzing erodability, and ground-water recharge scenarios needs to be analyzed.  ;

1

9. A soil moisture analysis should be performed on the site materials and geo-textile to determine hydraulic properties for the engineered layers. This work is presently underway for the weathered Lavery Till and should be the baseline data for the ground-water flow and leaching analysis of the tumulus.

10. High moisture contents and water films on the waste canisters may create b I a much higher leach rate than predicted and should be reassessed.

11. The gully development analysis does not include a PMF event nor other long-term severe hydrometeorological events. A very limited period of observa-tion makes a more detailed hydrologic analysis critical for adequately assessing the erosional scenarios.

1

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t

GENERAL COMMENT

S ON CHAPTER 3.0 0F DOE'S EA FOR GE0 TECHNICAL ASPECTS This chapter gives some conceptual details of the trench and tumulus design.

However, details of the different elements of the design (not provided) are vital if one has to decide whether the concepts described are viable or fatally

( flawed. Specific comments follow:

1. The quality of and the long term durability of the geotextile fabric is vital if both the trenches and the tumulus are to function as designed.

This aspect is not addressed in the EA.

2. Both the tumulus and trench will have to be designed for virtually zero settlement (static and dynamic) in order not to compromise the integrity of the textile, drains, etc. Construction and design details of how this is to be accomplished are not described.

3. Many vital engineering details are missing:

a. thickness and slopes of the different layers for both tumulus and trench designs

b. the safe free standing depths of trenches

c. details of bracing for trenches

d. details of piezometers, settlement plates, etc, (tumulus and trench) l and if these instruments will compromise the integrity of the system l e. construction details e.g., how is the clay layer to be placed and compacted above the waste barrels in the tumulus design and the l construction sequence (tumulus and trench)

f. compaction details (tumulus and trench)

g. QA procedures (tumulus and trench)

I

h. adequacy of filters to interface different materials of construction

i. filling of voids between the waste to ensure "no" settlement of the wastes

j. degradation of the waste and accompanying settlement i

k. earthquake design for trenches and tumulus, seismic design criteria '

and dynamic settlement '

l. details of layered toe drain of the tumulus

m. details of Geomechanical program SAGE and its verification (if any),

and applicability l

• t 2

GENERAL COMMENT

S ON DOE'S EA WITH RESPECT TO GE0 LOGIC ASPECTS

1. SCR, page 4-19, last paragraph, and page C-2, second paragraph.

, Possible explanations are given for the mechanisms causing the second set of fractures mapped in test trenches: (1) stress release related to move-ment along the Clarendon-Linden fault system, and (2) post glacial uplift.

Either of these explanations indicate tectonic or other deep seated regional stresses that were active in the late Pleistocene and Holocene, and may be currently causing deformation in the region. If ongoing, the significance of this phenomenon to the integrity of the disposal sites should be addressed.

2. EA, page 3-11, section 3.1.1.5.

l The criteria by which developing problems are identified through the short and long term monitoring program, when it is necessary to initiate a fix, and what type of fix will be done, should be provided.

3. A provision should be included in the report to geologically map in detail, the walls and floor of the trenches and the cleared earth surface below the tumulus.

4. It is indicated in several places in the SCR and EA that a seismic analysis ,

was performed. For example, on page G-24 it is stated that, with respect I to the stability of the tumulus, the Factor of Safety is greater than 2.0.

The seismic analysis should be presented along with the input data.

5. On page G-25, first paragraph, it is stated that after the containers begin to deteriorate, the seismic activity expected for this long-term period might trigger settling of wastes and disturb the integrity of the cover system resulting in increased infiltration. Describe the expected seismic activity and the potential consequences of increased infiltration caused by seismically induced settling of wastes.

6. Page G-24, Section G.3.1.2.

The second paragraph states that although vibratory ground motion might be experienced at the site, there is no likelihood of faulting or fissuring.

What maximum level of ground motions are likely to be experienced at the site? What will be the effect on the waste packages? Will the canisters contact one another (banging) during earthquake groundmotions?

I

7. Have the effects of ground motions in a shallow soil wedge over sloping l bedrock surface been analyzed (amplification, focussing)?

8. Page D-13.

In addition to buried settlement plates, monuments should be installed .,

prior to excavation of the trenches to measure heave as the site is unloaded.

9. In-situ sampling and testing of the soils to confirm physical properties

should be carried out during excavation of the trenches as well as testing the soil for radionuclides.

3

?

10. What techniques of compaction will be used to consolidate the backfill material between the waste packages? What criteria and QA and QC r.ethods l will be used to assure that a high quality job has been done? What frequency of testing, and what kinds of tests will be used?  !

11. Page D-12. A vibratory compactor is to be used on a 0.6m of clay placed  !

over a filler fabric above a 0.5m layer of pea gravel on top of the waste.

How will it be determined that the inter-container voids are completely j filled with gravel? Vibratory compactors will likely compact the gravel '

(if not too deep) but they are relatively ineffective in compacting clay.

Therefore, there is a possibility of voids after the gravel consolidates. I

12. Seepage is always greater along interfaces between penetrations and the f natural soil. This seepage is usually hard to predict. This is also pos- 1 sible along the interface between backfill and natural soil.

13. Figure D-19. It is not shown how the drainage blanket connects with the perimeter drainage system. This is an important connection.

I

14. The French experience with the tumulus concept should be described, along I with any other available case histories.

)

15. D-21. One of the barriers against future intrusion into the burial facility i

is cited to be the presence of rip-rap intruder barrier, because it will immediately appear as an unnatural feature. Human nature being what it is, it will probably promote continued and even accelerated excavation.

l l 16. Summary core boring logs should be included in the SCR.

i

17. SCR, page 4-26. The second paragraph implies that the Attica Earthquake was a MMI VII. This earthquake is officially classified as MMI-VIII (USGS).

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DETAILED COMENTS ON DOE'S SUBSURFACE CHARACTERIZATION REPORT, WVDP-046

1. Page 3-2 second line from last.

What were the engineering test data used to conclude that fractures can-not exist as open cracks below depths of 15 m.

2. General Comment Working drawings should be provided for figures such as A-1, 4-5, 6, 7, 13, 5-2, 3, 4, 5, 6, 7, 8, 9, 10, etc. These figures are not legible.

3. Pages 4-12, 13, 14, pages 5-29, 30, 31

Show the phreatic surface on these cross sections.

4. Table 5-2 Page 5-7 Some of the values of soil saturation (S) shown in this table indicate S as being below 100% (e.g., 90% and 96%) for samples at 16.1 and 18.3 meters below the surface, while S is over 100% in soils within 2 meters of the surface. Does this indicate that some samples dried out before testing or is there an error in the dry density measurements due to sample extru-sion from the borehole or is there some other reason for this apparent discrepancy? Correct determination of S is essential to delineate the phreatic surface at the site. In this regard it is important that more representative values of Specific Gravity, Gs, be determined.

5. Figure 5-1 Pressure head variations for dry periods and other wet periods should be shown to verify the trend that (page 5-19 first para) "a clearly downward gradient is implied by the displayed pressure head elevation relationship."

6. Figures 5-2, 3, 4, 5 The reasons for the erratic behavior of the tensiometers has not been described. Is there the possibility that they were not performing as expected due to faulty installation or equipment problems or both?

7. Figures 5-6, 7, 8 Have all available data been analyzed to plot the piezometric contours?

1

8. Figure 5-9 and page 5-28 last paragraph Have all available data been analyzed to plot the generalized piezometric contours of the site?

9. Provide Tables 5-8 and 5-9 (pages 4-45 and 5-56). "

10. Provide working drawings for Fig's 5-11 to 34.

5 l

.-- . _. = .. _ . . _.

11. Page 6-5 Relating quto blow counts is an approximate if not a crude method to compute q f r a clay soil.

u

12. Provide a working drawing for Fig. A-1, Appendix A.

~

13. Figure A-3, Appendix A, (Typical Pneumatic Piezometer Installation) and Figures B-5, B-6, B7, B8, Appendix B.

Described how the bentonite seals were installed to prevent clogging of the backfill sand and consequently erroneous readings of the pressure i head.

14. Please discuss the reason for not including ground and surface water model-ing of the tumulus design.

I

15. Page 4-25, Section 4.6.2 Flooding The discussion needs to be extensively augmented to include the flooding potential within and adjacent to the FDA. For instance, the runoff generated by local intense rainfall up to the PMP should be analyzed and provided. Reference to the sections on 4.6.4 Mass Wasting and 4.6.5 Potential for Gully Development at the Disposal Site should be made, and I

relate surface runoff and rainfall infiltration as generating mechanisms for mass wasting and gully development.

16. Page 4-26, Section 4.6.4 Mass Wasting i Again, this discussion is too brief and misses the real problem which is mass wasting in and around the FDA, and potential for future gully develop-ment and mass wasting. Any new construction and/or stabilization of either trenches or future tumulus will affect surface gradients, drainage, and topographic relief which act to drive this endemic phenomena at West Valley.

17. Page 4-29, Section 4.6.5 Potential for Gully at a Disposal Site This section appear to be far too biased towards present gully geometries and therefore appears to be a " static analysis" of a very dynamic activity.

The potential for gully development should discuss the generation of new gullies in and around the FDA, particularly for the options of (1) tumulus construction and (2) removal of the railroad grade. Road construction along the FDA has already modified the present gully, and its analysis should be a good indicator of how future human activities may affect the i potential for future gullying.

3

18. Pages 5-2 to 5-5, Section 5.1.1 Hydraulic Conductivity Relationships of unsaturated hydraulic conductivity R and R versus mois- s turecontent,andpressureheadviacharacteristiccufvessh6uldbe presented for the (1) weathered Lavery Till, I

6

. - . . _ _ , -.<-.------..-r -

n --nm- -- ---m--- - - - - - , ,----w - w.-n----, e<---~r"m--- - - - - - - - - + + - ~ - - ~~

(2) unweathered Lavery Till, and (3) Lucustrine unit.

The area affected by the solvent plume should be mapped, and increased permeability factors should be provided for the pathway analysis.

19. Pages 5-5 to 5-7, Section 5.5 Porosity

, Please provide discussion as to why % saturation exceeds 100% in the table on pg. 5-7.

Learning from the TBP-kerosene plume studies, the effective porosity, ne, of the weathered till needs to be reanalyzed. Using tracer data, an ne could be calculated that would be more representative of the fractured weathered till.

20. Page 5-14, Section 5.2 Piezometric and Tensiometric Data l This entire section, which is crucial to understanding the FDA and sur-rounding hydrogeologic system, needs to be updated to include all monitor-ing well data collected to the present. At present, information on the  ;

site data is missing although both USGS and NYSGS reports, and collected well records would allow a more complete site-wide perspective. The best  ;

potertial information source on the fractured system is missing and needs 1 to be included (i.e., TBP-kerosene plume monitoring well data).

21. Page 5-19, Section 5.2.3 Soil-Moisture Tension Data The interpretive picture is muddled. Recently collected data (since  !

October 1985) may help to resolve inconsistancies in the presented report.

The relationship between recharge, infiltration, and deep percolation has not been fully discussed and resolved due to the apparently inconsistent l data. Perhaps the data suffers from an early period of instrument adjust-j ment, or that tensiometers need to be routinely tested for reliability .

and accuracy.

22. Page 5-27, Section 5.3.1 Flow in the Lavery Till l_ The authors acknowledge the use of data from different time periods in order to develop the potentiometric contour maps. The use of data from l the same time period (i.e., daily data from the well records) is crucial.

Gradients in the upper till are especially susceptible to change and therefore an identical time period for' analysis is important. A 2 year continuous data base is very important for this very reason. Calibration and later validation of the conceptual models are dependent upon a common data reference point. ,

23. Page 5-34, Section 5.3.2 Flow in the Lacustrine Flow ,

The discussion is excellent but needs to examine recently collected data to verify that the conceptual model is correct. The contour map of Fig. 5-1 attests to the general lack of data and understanding, and needs to encompass more of the site monitoring wells.

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l 24. Page 5-34, Section 5.3.3 Flow in the Unsaturated Zone i The discussion needs to be updated and related to Section 5.2.3. The dis-cussion on recharge and affects on the shallow flow (water table) system l should be included.

25. Page 5-39, Section 5.5.3 Methodology The modeling is performed using 2-D cross-sectional configurations. The i

location and orientation of the modeled areas (2-D, 1-0 or 3-D), need to be discussed, and their inherent assumptions on flow directions and dis-charge rates need to be listed. (It is not sufficient to cite economical considerations).

Section 5.5.? Introduction The objective, not cited, which needs to be addressed is the need to fully model the present ground-water flow system in and adjacent to the FDA l before new activities and their alternatives can be discussed.

26. Page 5-50, Section 5.5.4.1 Calibration This section is incomplete. Information on calibration studies for all of the cross-sections modeled, and for comparison to more than just infiltration rates are needed (e.g., K and y K values h

or observed heads).

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4 --

APR 101986 MEMORANDUM FOR: Thomas Clark Advanced Fuel and Spent Fuel Licensing Branch Division of Fuel cycle and Material Safety, NMSS FROM: Leon L. Beratan, Chief Earth Sciences Branch Division of Radiation Programs and Earth Sciences, RES

SUBJECT:

WEST VALLEY ENVIRONMENTAL ASSESSMENT We have reviewed the draft West Valley Environmental Assessment report which you distributed. Attached are our comments. The comments were provided by the members of the Earth Sciences Branch. Any questions concerning these coments should be addressed to:

1 Thomas J. Nicholson, Hydrology (extension 74039)  ;

Jacob Philip, Geotechnical (extension 74604)

Richard McMullen, Geology (extension 74318)

I l

Leon L. Beratan, Chief Earth Sciences Branch Division of Radiation Programs

! and Earth Sciences, RES

Enclosure:

I Coments Distribution /R-2811:

Circ Ch on RMinogue EConti RMcMullen DCS PD Dross LBeratan JPhilip ESB j/Rd KGoller IN vAMurphy RKornasiewicz ESB:RESy h

ESB:RES:mb ESB:RES ESB:RES ESB:RES:MK ESB:REgLBeratan TNicholson JPhilip [ RMcMullen RKornasiewicz AMurphy g /Est36 J /yd86 4/4 /86 Oy/a7 /86 /l0/86 3/Q/86

GENERAL COMMENT

S ON DOE'S EA WITH RESPECT TO HYDROLOGIC ASPECTS

1. The on-site storage alternative for a given period of time (e.g., 5 years) should be given more consideration since (a) there is a lack of experience with the tumulus methodology; (b) there is lack of experience with " success-ful" trench methodology; and (c) there is a lack of ground-water and surfi-cial erosional data base for the site (a minimum of 2 year background surveillance).

2. The leaching rate for less than saturated conditions (i.e., high moisture contents) that would provide sufficient leaching to equal the overall radionuclide release performance of the tumulus for comparison to the trenches should be provided for the lifetime of the waste facility. The moisture content versus leaching curves for the tumulus need to be provided and the design basis characteristics curves for the engineered layers with 1 time need to be provided.

3. The below ground options and failure scenarios for the trenches are highly restrictive and limited. Other alternatives which would provide for longer pathways and travel times (i.e., different burial geometries and locations) need to be considered and discussed.

4. Insufficient site characterization and baseline data prevent a fair com-parison of alternatives for both the trench and tumulus options.

5. Failure scenarios to be assessed for the tumulus should include " clogging" of the toe drain and local saturated conditions in the base of the tumulus that would allow a high leach rate for the entombed waste.

6. Stability of the trench, both for cap settlement and waste subsidence, needs closer attention.

7. Differential settlement of the tumulus layers needs closer attention.

8. A detailed analysis of local intense rainfall events for both the tumulus and trenches for analyzing erodability, and ground-water recharge scenarios needs to be analyzed.

9. A soil moisture analysis should be performed on the site materials and geo- )

textile to determine hydraulic properties for the engineered layers. This l work is presently underway for the weathered Lavery Till and should be the baseline data for the ground-water flow and leaching analysis of the tumulus. ,

10. High moisture contents and water films on the waste canisters may create . ' ,

a much higher leach rate than predicted and should be reassessed.

11. The gully development analysis does not include a PMF event nor other long-term severe hydrometeorological events. A very limited period of observa-tion makes a more detailed hydrologic analysis critical for adequately assessing the erosional scenarios.

1 e

l l

GENERAL COMMENT

S ON CHAPTER 3.0 0F DOE'S EA FOR GE0TLCHNICAL ASPECTS This chapter gives some conceptual details of the trench and tumulus design.

However, details of the different elements of the design (not provided) are vital if one has to decide whether the concepts described are viable or fatally flawed. Specific comments follow:

1. The quality of and the long term durability of the geotextile fabric is vital if both the trenches and the tumulus are to function as designed.

This aspect is not addressed in the EA.

2. Both the tumulus and trench will have to be designed for virtually zero settlement (static and dynamic) in order not to compromise the integrity of the textile, drains, etc. Construction and design details of how this is to be accomplished are not described.

3. Many vital engineering details are missing:

a. thickness and slopes of the different layers for both tumulus and trench designs

b. the safe free standing depths of trenches

c. details of bracing for trenches

d. details of piezometers, s'ettlement plates, etc, (tumulus and trench) and if these instruments will compromise the integrity of the system

e. construction details e.g., how is the clay layer to be placed and compacted above the waste barrels in the tumulus design and the -

construction sequence (tumulus and trench)

f. compaction details (tumulus and trench)

g. QA procedures (tumulus and trench)

h. adequacy of filters to interface different materials of construction

i. filling of voids between the waste to ensure "no" settlement of the wastes

j. degradation of the waste and accompanying settlement

k. earthquake design for trenches and tumulus, s,eismic design criteria and dynamic settlement

1. details of layered toe drain of the tumulus

m. details of Geomechanical program SAGE and its verification (if any),

and applicability

• f

• t 2

i l

GENERAL C0pmENTS ON 00E'S EA WITH RESPECT TO GEOLOGIC ASPECTS

1. SCR, page 4-19, last paragraph, and page C-2, second paragraph.

i Possible explanations are given for the mechanisms causing the second set of fractures mapped in test trenches: (1) stress release related to move-( ment along the Clarendon-Linden fault system, and (2) post glacial uplift.

l Either of these explanations indicate tectonic or other deep seated regional I stresses that were active in the late Pleistocene and Holocene, and may be i currently causing deformation in the region. If ongoing, the significance of this phenomenon to the integrity of the disposal sites should be t

addressed.

2. EA, page 3-11, section 3.1.1.5.

The criteria by which developing problems are identified through the short and long term monitoring program, when it is necessary to initiate a fix, and what type of fix will be done, should be provided.

3. A provision should be included in the report to geologically map in detail, the walls and floor of the trenches and the cleared earth surface below the tumulus. l

4. It is indicated in several places in the SCR and EA that a seismic analysis was performed. For example, on page G-24 it is stated that, with respect to the stability of the tumulus, the Factor of Safety is greater than 2.0.

The seismic analysis should be presented along with the input data.

l

5. On page G-25, first paragraph, it is stated that after the containers begin j to deteriorate, the seismic activity expected for this long-term period might trigger settling of wastes and disturb the integrity of the cover i system resulting in increased infiltration. Describe the expected seismic activity and the potential consequences of increased infiltration caused by seismically induced settling of wastes.

6. Page G-24, Section G.3.1.2.

The second paragraph states that although vibratory ground motion might l be experienced at the site, there is no likelihood of faulting or fissuring.

What maximum level of ground motions are likely to be experienced at the site? What will be the effect on the waste packages? Will the canisters contact one another (banging) during earthquake groundmotions?

7. Have the effects of ground motions in a shallow soil wedge over sloping bedrock surface been analyzed (amplification, focussing)?

8. Page D-13.

In addition to buried settlement plates, monuments should be installed .I prior to excavation of the trenches to measure heave as the site is ,

unloaded. .;

9. In-situ sampling and testing of the soils to confirm physical properties should be carried out during excavation of the trenches as well as testing the soil for radionuclides.

3 i

10. Wh:t t:chniques cf compactirn will be us:d to c:nsolidate the b:ckfill materic1 bitwe:n the w;sta psckages? Wh:t crit;ria cnd QA cnd QC methods will be used to assure that a high quality job has been done? What frequency of testing, and what kinds of tests will be used?

11. Page D-12. A vibratory compactor is to be used on a 0.6m of clay placed over a filler fabric above a 0.5m layer of pea gravel on top of the waste.

How will it be determined that the inter-container voids are completely filled with gravel? Vibratory compactors will likely compact the gravel (if not too deep) but they are relatively ineffective in compacting clay.

Therefore, there is a possibility of voids after the gravel consolidates. j

12. Seepage is always greater along interfaces between penetrations and the natural soil. This seepage is usually hard to predict. This is also pos-sible along the interface between backfill and natural soil.

13. Figure D-19. It is not shown how the drainage blanket connects with the perimeter drainage system. This is an important connection.

14. The French experience with the tumulus concept should be described, along with any other available case histories.

15. D-21. One of the barriers against future intrusion into the burial facility is cited to be the presence of rip-rap intruder barrier, because it will immediately appear as an unnatural feature. Human nature being what it is, it will probably promote continued and even accelerated excavation.

16. Summary core boring logs should be included in the SCR.

17. SCR, page 4-26. The second paragraph implies that the Attica Earthquake was a MMI VII. This earthquake is officially classified as MMI-VIII (USGS). j T

1

.e f

4 l

_ _ _ _ ~ . - _ _ _ _ _ _ _ _ _ _ -- ._ . _ _.

. DETAILED COMMENTS ON DOE'S SUBSURFACE CHARACTERIZATION REPORT, WVDP-046

1. Page 3-2 second line from last.

What were the engineering test data used to conclude that fractures can-not exist as open cracks below depths of 15 m.

2. General Comment Working drawings should be provided for figures such as A-1, 4-5, 6, 7, 13, 5-2, 3, 4, 5, 6, 7, 8, 9, 10, etc. These figures are not legible.

3. Pages 4-12, 13, 14, pages 5-29, 30, 31 Show the phreatic surface on these cross sections.

4. Table 5-2 Page 5-7 Some of the values of soil saturation (S) shown in this table indicate S as being below 100% (e.g., 90% and 96%) for samples at 16.1 and 18.3 meters below the surface, while S is over 100% in soils within 2 meters of the surface. Does this indicate that some samples dried out before testing or is there an error in the dry density measurements due to sample extru- i sion from the borehole or is there some other reason for this apparent discrepancy? Correct determination of S is essential to delineate the phreatic surface at the site. In this regard it is important that more representative values of Specific Gravity, Gs, be determined.

l

5. Figure 5-1 l

Pressure head variations for dry periods and other wet periods should be shown to verify the trend that (page 5-19 first para) "a clearly downward

gradient is implied by the displayed pressure head-elevation relationship." 1

6. Figures 5-2, 3, 4, 5 l The reasons for the erratic behavior of the tensiometers has not been described. Is there the possibility that they were not performing as expected due to faulty installation or equipment' problems or both?

7. Figures 5-6, 7, 8 Have all available cata been analyzed to plot the piezometric contours?

8. Figure 5-9 and page 5-28 last paragraph Have all available data been analyzed to plot the generalized piezometrir..

contours of the site?

9. Provide Tables 5-8 and 5-9 (pages 4-45 and 5-56).

l

10. Provide working drawings for Fig's 5-11 to 34.

4 5

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- ,- -- - - w,_

- ,- =--- - ,- .- , _ _

- 11. Pag 3 6-5 Relating q to blow counts is an approximate if not a crude method to compute q,ufor a clay soH.

12. Provide a working drawing for Fig. A-1, Appendix A.

13. Figure A-3, Appendix A, (Typical Pneumatic Piezometer Installation) and

- Figures B-5, B-6, B7, B8, Appendix B.

Described how the bentonite seals were installed to prevent clogging of the backfill sand and consequently erroneous readings of the pressure head. ,

34. Please discuss the reason for not including ground and surface water model-ing of the tumulus design.

15. Page 4-25, Section 4.6.2 Flooding l The discussion needs to be extensively augmented to include the flooding j potential within and adjacent to the FDA. For instance, the runoff generated by local intense rainfall up to the PHP should be analyzed and provided. Reference to the sections on 4.6.4 Mass Wasting and 4.6.5 Potential for Gully Development at the Disposal Site should be made, and relate surface runoff and rainfall infiltration as generating mechanisms for mass wasting and gully development.

16. Page 4-26, Section 4.6.4 Mass Wastina Again, f,his discussion is too brief and inisses the real problem which is mass wasting ir} and around the FDA, and potential for future gully develop-ment and mass wasting. Any new construction and/or stabilization of either trenches or future tumulus will affect surface gradients, drainage, and topographic relief which act to drive this endemic phenomena at West Valley.

17. Page 4-29, Section 4.6.5 Potential for Gully at a Disposal Site This section appear to be far too biased towards present gully geometries and therefore appears to be a " static analysis" of a very dynamic activity.

The potential for gully development should discuss the generation of new gullies in and around the FDA, particularly for the options of (1) tumulus construction and (2) removal of the railroad grade. Road construction along the FDA has already modified the present gully, and its analysis should be a good indicator of how future human activities may affect the l potential for future gullying.

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18. Pages 5-2 to 5-5, Section 5.1.1 Hydraulic Conductivity - I Relationships of unsaturated hydraulic conductivity R and R versusmois,(

turecontent,andpressureheadviacharacteristiccufvesshhuldbe presented for the (1) weathered Lavery Till, 6

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(2) unweather;d Lcvery Till, cnd (3) Lucustrine unit.

The area affected by the solvent plume should be mapped, and increased permeability factors should be provided for the pathway analysis.

19. Pages 5-5 to 5-7, Section 5.5 Porosity Please provide discussion as to why % saturation exceeds 100% in the table on pg. 5-7.

Learning from the TBP-kerosene plume studies, the effective porosity, ne, of the weathered till needs to be reanalyzed. Using tracer data, an ne could be calculated that would be more representative of the fractured weathered till.

20. Page 5-14, Section 5.2 Piezometric and Tensiometric Data This entire section, which is crucial to understanding the FDA and sur-rounding hydrogeologic system, needs to be updated to include all monitor-ing well data collected to the present. At present, information on the site data is missing although both USGS and NYSGS reports, and collected well records would allow a more complete site wide perspective. The best potential information source on the fractured system is missing and needs to be included (i.e., TBP-kerosene plume monitoring well data).

21. Page 5-19, Section 5.2.3 Soil-Moisture Tension Data The interpretive picture is muddled. Recently collected data (since October 1985) may help to resolve inconsistancies in the presented report.

The relationship between recharge, infiltration, and deep percolation has not been fully discussed and resolved due to the apparently inconsistent data. Perhaps the data suffers from an early period of instrument adjust-ment, or that tensiometers need to be routinely tested for reliability and accuracy.

22. Page 5-27, Section 5.3.1 Flow in the Lavery Till The authors acknowledge the'use of data from different time periods in order to develop the potentiometric contour maps. The use of data from the same time period (i.e., daily data from the well records) is crucial.

Gradients in the upper till are especially susceptible to change and therefore an identical time period for' analysis is important. A 2 year continuous data base is very important.for this very rea ;on. Calibration and later validation of the conceptual models are dependent upon a common data reference point.

23. Page 5-34, Section 5.3.2 Flow in the Lacustrine flow The discussion is excellent but needs to examine recently collected data to verify that the conceptual model is correct. The contour map of "

Fig. 5-1 attests to the general lack of data and understanding, and needs to encompass more of the site monitoring wells.

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• 24. P:g] 5-34, S:ctirn 5.3.3 Flow in th7 Unscturated Z'ne The discussion needs to be updated and related to Section 5.2.3. The dis-cussion on recharge and affects on the shallow flow (water table) system should be included.

25. Page 5-39, Section 5.5.3 Methodology The modeling is performed usirg 2-D cross-sectional configurations. The location and orientation of the modeled areas (2-D, 1-D or 3-D), need to be discussed, and their inherent assumptions on flow directions and dis-charge rates need to be listed. (It is not sufficient to cite economical considerations).

Section 5.5.2 Introduction The objective, not cited, which needs to be adcressed is the need to fully model the present ground-water flow system in cad adjacent to the FDA before new activities and their alternatives can be discussed.

26. Page 5-50, Section 5.5.4.1 Calibration This section is incompitte. Information on calibration studies for all of the cross sections modeled, and for comparison te moie than just infiltration rates are needed (e.g., K yand K hvalues r observed heads). .

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