ML17297B566

Informs of Latest Developments Re Possible Fault Scarps in Area of Station,As Followup to Util to Nrc. Excavations Showed Positive Evidence That Faulting Could Not Be Cause of Scarps

ML17297B566
Person / Time
Site:	Palo Verde
Issue date:	06/16/1982
From:	Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 8206180004
Download: ML17297B566 (10)

Text

REGULATOfi INFORMATION DISTRIBUTION TEM (RIDS)

AOCBS SION NBR: 820 FACIL:STN"50"528 STN.50 529 STN-50-530 AUTH INANE VAN BRUNTiE ~ E,

'RGC IP. NAME DENTONiH ~ RE 6180004 DOC.DATE: 82/06/16 NOTARIZED:

YES

'Palo Verde Nuclear Stationi Un)~t ii Arizona Publi Palo Verde Nuclear Stationi Unit 2~ Arizona Pub)i Palo Verde Nuclear Stationi Unit 3i Arizona Publi AUTHOR AFFILIATION Arizona Public Service Co.

RECIPIENT AFFILIATION Office of Nuclear Reactor Regulationi Director DOCKET 05000528 05000529 05000530

SUBJECT:

Informs of latest developments re possible fault scarps in area of stationias followup to util 820610 ltr to NRC.

Excavations showed positive evidence that faul~ting could not be cause of scarp'ISTRIBUTION CODE:

B001S

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TITLE: PSAR/FSAR AMDTS and Related Correspondence NOTES:Standardized plant.

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ggo gq 9-WXfXMtQ~aa CIOIKMIWP P. O. BOX 2I666 'HOENIX ARIZONA BSO36 June 16, 1982 Mr. Harold R.

Denton, Director Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D.C.

20555

Dear Mr. Denton:

This letter is a followup to our June 10th letter notifying the NRC of the recent interpretations of fault scarps in the area of the Palo Verde Nuclear Generating Station by Hr.

Henges of the Arizona Bureau of Geology and Mineral Technology.

Since June 10th, some very significant progress has been made in resolving this issue and this letter will summarize the latest developments.

On June 11th, Arizona Public Service Company made a press release to all news media regarding the possible fault scarps near the Hassayampa River area.

In addition, late that same afternoon, APS received a land access permit from the BLM along with a commitment to provide BLM right-of-way personnel and an archaelogist for any weekend work.

Early Saturday morning, June 12th, Hr. Scott, our geologic consultant, and Hr. Henges along with BLM personnel, cleared the access route and selected two locations for trenches across the most prominent scarps in the area.

The trench locations were carefully selected to analyze the most significant scarps designated by Mr. Menges and to investigate those areas with the highest likelihood of uncovering definitive characteristics for analyzing faults.

The trenching was begun in late morning on June 12th using two rubber-tired backhoes and continued through Sunday, June 13th.

The trenches were oriented at right angles to the scarps and the trench lengths ranged from about 100 feet to 225 feet in order to investigate well beyond the scarp limits.

Depth of both trenches averages about 14 feet which was sufficient to clearly reveal at least three major stratigraphic units with sharp and distinctive contacts.

In general terms these three units consisted of an upper gravel "cap" several feet thick below the ground surface, a very fine grain salty sand unit, and, in the lower half of the trench, a gray sand and gravel unit.

There were many correlable subunits within this lower sand and gravel unit.

lilith the exception of the upper gravel "cap," all of the major stratigraphic units and many of the subunits showed clear, undisturbed continuity for the full length of the trenches.

The stratigraphic units were essentially horizontal without any evidence of tectonic warping or displacement.

The upper gravel

cap, as would be expected, is only preserved at the uphill side of the scarp and is gradually thinned and eliminated by surface erosion on the downhill side of the scarp.

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~'DR ADOCK 05000528

4

Mr. Harold R. Denton, Director Nuclear Reactor Regulation U.

S. Nuclear Regulatory Commission Page 2

June 16, 1982 Mr. Menges and Mr. Scott monitored the trenching constantly and carefully inspected all excavations.

At the conclusion of the excavation and inspection there was a concurrence that the excavations showed positive, conclusive evidence that faulting could not be the cause of'he scarps.

Instead, the original interpretation of the Palo Verde geologic studies was confirmed, i.e., that the scarps occur at the edges of older alluvial fan deposits which have been preserved at higher elevations.

As a result, Mr. Menges has.indicated that he will be revising his inter-pretation of the scarps and will remove all the "possible faults" in the Hassayampa area from the map he is currently preparing for his U.

S.

Geological Survey investigation.

Currently, the trenches are being logged in detail for proper documentation and in preparation for a site visit by the NRC.

On June 16th and 17th, Mr. Harold Lefevre will be visiting the area to inspect the trenches, perform a low sun angle flyover and discuss the interpretations.

'ery truly yours, E.

E.

Van Brunt, Jr.

APS Vice President, Nuclear Projects ANPP Project Director lb

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Distribution:

Atomic Safety Licensing Board Robert N. Lazo, Esq.,

Chairman Dr. Richard F.

Cole Dr. Dixon Callahan Lee Scott

Dewey, Esq.

Docketing and Service Section U.

S. Nuclear Regulatory Commission Washington, D.C.

20555 Lynne Bernabei, Esq.,

Marmon Weiss Art Gehr, Snell

& Wilmer

I

STATE OF ARIZONA.

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SS

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COUNTY OF MARICOPA)

I, Edwin E. Van Brunt, Jr., represent that I am Vice President Nuclear Projects of Arizona Public Service Company, that the foregoing document has been signed by me on behalf of Arizona Public Service Company with full authority so to do, that I have read such document and know its contents, and that to the best of my knowledge and belief, the statements made therein are true.

Edwin E., Van Brunt, Jr.

Sworn to before me this'/(n day of s spy

/

Notary Public 1981.

hy Commission expires:

iij vdNmissiog Expires March 11,19S8.

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