ML20198G580

Summmary of 741220 Meeting W/Wppss,Ebasco & Woodward-Clyde in Bethesda,Md to Discuss Landslides & Slope Stability

ML20198G580
Person / Time
Site:	Satsop
Issue date:	01/21/1975
From:	Oreilly P Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
CON-WNP-1320 NUDOCS 8605290684
Download: ML20198G580 (6)

Text

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UNITED STATES

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NUCLEAR REGULATORY COMMIS$10N W AsHINGToN, D. C. 20555 JAN. 21 1975 DOCKLT NOS: STN 50-508 AND STN 0-509 APPLICANT: WASHINGTON PUBLIC POWER SUPPLY SYSTEM (WPPSS)

FACILITY: nPPSS NUCLEAR PROJECTS NO. 3 AND NO. 5 SU> NARY OF DLCEMBER 20, 1974 MEETING WITH WPPSS TO DISCUSS LANDSLIDES AND SLOPE STABILITY On December 20, 1974, representatives of WPPSS, Ebasco, and Woodward-Clyde (formerly Woodward-Lundgren) met with the Regulatory staff in Bethesda, Maryland. This meeting was requested by WPPSS to discuss their studies on landslides and slope stability in the region near the proposed site of WPPSS Nuclear Projects No. 3 and No. 5.

Woodward-Clyde, the applicant's geologic consultant, described a reconnaissance study of landslides in the site area. This study was still in progress on landslide area No. 8 (designation in Section 2.5 of the PSAR).

Woodward-Clyde described landslide area No. I as a fluid mass type of landslide. It is located approximately 9000 feet from the plant site with a large portion of its lower surface resting on siltstone.

This landslide was described as having failed on a mappable unit of siltstone in the Astoria formation. The techniques for mapping landslide area No. I were described. The results of the investigation of landslide area No. 1 indicate that this slide is at least several thousand years old.

In their description of landslide area No. 3, Woodward-Clyde characterized this slide as one that is not a flow slide. Landslide area No. 3 is situated on the same siltstone as landslide area No.

1. The age of slide area No. 3 is approximately the same as the age of area No. 1. The originating mechanism for this landslide was described as being the same as that for area No.1 (failure of a thick unit of siltstone).

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4 JAN. 21 '973 Both landslide areas No. 4 and No. 6 were described by Woodward-Clyde as fluid mass slides. Landslide area No. 4 was characterized as a complex area - it is actually composed of a number of slides.

Landslide area No. 4 is situated on a siltstone unit that is a different unit from the siltstone in landslide areas No. I and No. 3.

Woodrard-Clyde summarized the studies performed on landslide areas No. 1, No. 3, No. 4, and No. 6. They emphasized that all four landslides failed on prominent, mappable units of siltstone in the Astoria formation. The two mappable siltstone beds associated with these four slides were the only two such siltstone beds found in the region near the site. Woodward-Clyde stated that siltstone had an important role in the formation of these landslides in the site region.

They have identified the following as factors in landslide formation:

failure on dip slopes, failure on weak units (e.g., siltstone),

weathering (in some cases, deep weathering), undercutting, and ground-water.

Woodward-Clyde described landslide area No. 2 (located 9000 feet southwest of the plants) as a rigid slide. There are no exposures of the slide plane itself in this landslide. All observable evidence indicates the same mechanisms of slide formation as were discussed in the cases of landslide area Nos. 1, 3, 4 and 6.

Landslide areas No. 5 and No. 7 were described by Woodward-Clyde as small, earth flow type slides on dip slopes in steep gulleys.

Landslide area No. 8 is located 450 feet south of the plants. Woodward-Clyde stated that this slide area is older (because of the lack of geomorphic evidence) than other slides in the site region. Red clay was observed in core boring D-10, which was recovered from the base at the slide area. The slippage surface is associated with the red clay. Thus the slippage surface was readily traceable. No such clay was found in the core borings obtained from the plant site itself.

From their investigation of these landslides, Woodward-Clyde concluded that the geologic conditions observed in the landslide areas near the site differ from those observed at the site (i.e., absence of deep weathering, steeply dipping slopes, and undercut bedding). As a result, they claim that the conditions for potential landslides do not exist in the plant area itself.

JAN. 21 137 fi Woodward-Clyde stated that they are not studying the potential for a landslide to occur offsite and then move into the plant area.

WPPSS a' greed to document the results of the study of landslides by mid-January 1975.

4ddc Patrick D. O'Reilly et (j Light Water Reactors Project Branch 1-3 Division of Reactor Licensing

Enclosure:

Attendance List cc w/ enc 1:

Mr. J. J. Stein Joseph B. Knotcs, Jr. , Esq.

Richard Q. Quigley, Esq.

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h ENCLOSURE

, ATTENDANCE LIST MEETING WITH WPPSS DECEMBER 20, 1974 WASHINGTON PUBLIC POWER SUPPLY SYSTEM D. B. Whitford G. C. Sorensen EBASCO A. Wern WOODWARD-CLYDE A. Patwardhan M. Perkins .

NUCLEAR REGULATORY COMMISSION P. O'Reilly D. R. Budge J. T. Greeves

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Distribution: /

Docket Fil S. Varga j AEC PDR R. W. Klecker local PDR F. Schroeder LWR 1-3 Reading R. Tedesco LWR 1-3 File V. Stello L Reading (M. Groff) R. Maccary R. C. DeYoung H. Denton V. A. ) bore V. Benamya D. Skovholt C. Inng D. Maller G. Lainas R. Denise D. Ross K. Goller T. Ippolito W. Butler J. Knight J. Stolz S. Pawlicki R. Clark L. Shao R. Ireland B. Grimes D. Vassallo W. Gamill K. Kniel R. Ballard O. D. Parr P. Fine A. Schwencer T. !bvak R. Purple M. Spangler D. Zianann S. Kastner P. Collins EP Project Manager - J. Norris G. Knighton Project Manager - P. O'Reilly G. Dicker Attorney, OGC B. Youngblood R0 (3)

W. Regan, Jr. V. H. Wilson R. Vollmer ACRS (12)

W. Houston F. Kantor G. Lear T. Johnson C. Stepp D. Budge T. Rarphy R. Karnasiewicz C. Liang P. Stoddart J. Costello F. Cherney P. Chen E. Brooks l

R. Satterfield F. Ashe M. Bolotsky I. Sihweil i V. Goel J. Greeves G. Mainz L. Phillips R. Q11p

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0-i Distribution: -

Docket Filey S. Varga AEC PDR R. W. Klecker local PDR F. Schroeder LWR 1-3 Reading R. Tedesco LWR 1-3 File V. Stello L Reading (M. Groff) R. Maccary R. C. DeYoung H. Denton V. A. Moore V. Benamya D. Skovholt C. Iong D. mller G. Lainas R. Denise D. Ross K. Go11er T. Ippolito W. Butler J. Knight J. Stolz S. Pawlicki R. Clark L. Shao R. Ireland B. Grimes D. Vassallo W. Ganmill K. Kniel R. Ballard O. D. Parr P. Fine A. Schwencer T. Novak R. Purple M. Spangler D. Zianann S. Kastner P. Collins EP Project Manager - J. Norris G. Knighton Project Manager - P. O'Reilly G. Dicker Attorney, OGC B. Youngblood R0 (3)

W. Regan, Jr. V. H. Wilson ,

R. Vollmer ACRS (12)

W. Houston F. Kantor G. Lear T. Johnson C. Stepp D. Budge T. W rphy R. Kornasiewicz C. Liang P. Stoddart J. Costello F. Cherney P. Chen E. Brooks R. Satterfield F. Ashe M. Bolotsky I. Sihweil V. Goel J. Greeves G. Mainz L. Phillips R. Culp l

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