ML20213D582

Summarizes 810312 Telcon W/Util Re Discoveries in Trenches. Complex Clastic Dikes Occur in Trenches.Dikes Are Probably Derived from One Source Bed

ML20213D582
Person / Time
Site:	Columbia
Issue date:	03/19/1981
From:	Justus P Office of Nuclear Reactor Regulation
To:	Rolonda Jackson Office of Nuclear Reactor Regulation
References
CON-WNP-0340, CON-WNP-340 810119, NUDOCS 8103270264
Download: ML20213D582 (2)

Text

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q bid 5- N 1 S }gg; MEMORANDUM FOR: Robert E. Jackson, Chief Geosciences Branch, DE THRU:

FROM:

Richard B. McMullen, Acting Leader Geology Section, GSB, DE Philip S. Justus, Geologist

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Geology Section, GSB, DE os  ?

SUBJECT:

C0tlFERENCE CALL WITH WPPSS, USGS, GSB ON *s OISCOVERIES IN TRE!!CHES FOR WNP-2 PRGJECT Jerry Sorensen of WPPSS arranged for Tim Hait and GSB (J. Kimball, A. Ibrahim, myself) via conference call (2:00 - 2:50 p.m. March 12th) to be appraised of findings of the latest trenching efforts across selected air photo linears. WPPSS felt obliged to notify us now as there is a need to backfill the trenches near Priest Rapids dan by April 1st and a need to decide whether to shore the trenches near Wallula Gap. WPPSS-affiliated people on the line were: Sorensen, Tillsog, Kiel, Waddell, Davis, Coombs, Hitchcock, Caldwell, Doherty and Burton.

Don Caldwell briefly explasned Golder Associates' trenching program and results from Priest Rapids Dam area. Golder has placed 12 trenches across four air photo linear- the longest linear is five miles, the otherrare less than one mile. All trenches apcear to be in the hanging wall of the ted l

Umtanum thrust fault. All trenches except one are in well cemented fanglome l

showing neither offsets nor joints. One trench revealed defomed contacts within a basalt flow unit and interbed. The interbed is slichensided. This deformation is considered intraformational and atectonic. Trenches are located in sections 31 and 32 on west edge of Priest Rapids 7 1/2' quadrangle. The linears appear

! to be due to soil failure. The longest linear may be an old Indian trail. The l " trail" has been investigated by an archeologist who apparently supports the idea.

Don Hitchcock briefly explained Woodward-Clyde's trenching program and results from Wallula Gap area. W-C has placed two trenches across Bingham's (1971) linear; they are about 120 ft long and 18 ft deep. Both are completely within the Touchet beds. There are offsets in the Touchet of several inches. Complex clastic dikes occue in the trenches and there is a strong suggestion that the dikes are derived from one source bed. The offsets are considered to be related to " diking". Groundhog burrows are concentrated along the linear. W-C postulates that the linear is a cultural feature and could be a relict Indian trail. ff

, In a later conversation with me, Tim Hait decided to visit the trenches during l

the week of March 23rd. He feels that these and other linears will need to be

. reviewed carefully-and a. visit to taese trencbes_would be_an.appropr_iate _ _ _ _ _ _ _

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DI5TRIBUTI0ti:

CENTRAL FILE GSB RDG 1 g ISel I called Jerry Sorensen to inform him of Tim's visit, that Tim would appreciate being sent stereopairs of the linears and trench locations in advance of his visit, and that Tim would be in touch with him about arrangements for the site visit. I thanked Jerry for notifying us and arranging the conference call.

Philip S. Justus, Geologist Geology Section Geosciences Branch, DE cc: R. ficMullen J. Kinball A. Ibrahim D. Lynch P. Justus l

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