ML20147C875

Provides Results of 771216 Site Visit to Observe Topography & Geology Exposed in Trenches.Further Study Is Needed to Determine Certain Absence of Faulting at Site

ML20147C875
Person / Time
Site:	Vallecitos File:GEH Hitachi icon.png
Issue date:	01/30/1978
From:	Kurkjian T INTERIOR, DEPT. OF, GEOLOGICAL SURVEY
To:	Stepp C Office of Nuclear Reactor Regulation
References
780110, SPNED-D, NUDOCS 7812180431
Download: ML20147C875 (2)

Text

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p$tyf DEPARTMENT OF THE ARP, F SAN FRANCISCO DISTRICT, CORPS oF ENclNEERS

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Dr. Carl Stepp . F Chief, Geosciences Branch G Division of Site Safety and Environmental Analysis U.S. Nuclear Regulatory Commission Washington D.C., 20555

Dear Dr. Stepp:

On 16 November 1977, Mr. T. R. Coffman of the U.S. Army Engineer District, San Francisco attended a site inspection of the Vallecitos Huclear Center at the request of Mr. John Grieves of your branch. The purpose of the visit was to observe topographic features and geologic features exposed in trenches 1, 2, and 3 at the site. An overview of the site geology and investigations completed to date were presented by the General Electric Company Consultants.

Obsevations of the features viewed at the site by Mr. Cof fman were trans-mitted by telephone on 29 November 1977 to Mr. Bob Jackson of your branch and are as follows:

a. Based on the data presented by General Electric's Consultants at the 16 November 1977 meeting and site inspection, features adjacent to the site on the west slope of the ridge northeast of the nuclear facility could be related to a landslide origin.

b. The absence of faulting at the site based on the hypothesis that a well cemented, conglomeratic unit (located south of the site) is an older, basal member of the Livermore formation and is not offset or de-formed in an area on line with previously mapped locations of the Verona fault would be core viable if the following is demonstrated:

(1) The age of the conglomeratic unit is better established relative to the Livermore formation.

781218043l

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.. ~ s s w SPNED-D 10 January 1978 Dr. Carl Stepp (2) The conglomeratic unit is unfaulted beneath the site and area immediately northeast of the site.

c. Determination of the origin of the mound-like feature near the center of the Vallecitos facility may be an aid in better understanding other ur-face features in the area.

If we can be of further assistance to you, please contact us.

Sincerely yours,

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/ ',mu V THOMAS G. KURKJ AN s .

CPT, CE Acting Chief, Engineering Division 2

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