ML20065F276

Proposes to Discontinue Survey Between North Anna Main Dam Ref Monuments & Us Coast & Geological Survey Monuments Performed Once Every 10 Yrs to Verify Locations of Ref Monuments

ML20065F276
Person / Time
Site:	North Anna
Issue date:	04/05/1994
From:	Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	Crisp R FEDERAL ENERGY REGULATORY COMMISSION
References
F93-018, F93-18, NUDOCS 9404110295
Download: ML20065F276 (2)

Text

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JAMts P. O'llANLON - ' innsbrook Technical Cente

] lb . Vice President - Nuclear Operations 5000 Dominion Boulentd ,

Glen Allen, Virginia 2J060 806 273 2101

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l l  :

h April 5, 1994 3

[ Mr. R. W. Crisp Serial No. F93-018 j LRegional Director .  !

Federal Energy Regulatory Commission '

i 3125 Presidential Parkway, Suite 300 f Atlanta,. Georgia 30340 i 'i

Dear Mr. Crisp:

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PROJECT NO. 6335-VA "

j NORTH ANNA HYDROELECTRIC PROJECT

!- TEN-YEAR SURVEY OF REFERENCE MONUMENTS AT MAIN DAM V

l Currently, the survey between the North Anna main dam's reference monuments and the United States Coast and' Geological (USC&G) Survey monuments is.

] performed once every ten years to verify the locations of the reference monuments.

j. We have determined that the survey.between the monuments does not provide j significant information relative to settlement'or horizontal movement of.the dam. a '

We have discussed this with Mr. J. C. Lyon, Jr. of your office.

! The bases-for our determination are the stability ~of the main dam's reference

. monuments and the relative distance between the main dam's monuments and I those of the USC&G. The main dam's reference monuments are founded in rock ,

! and therefore are inherently more stable than the USC&G Survey monuments which are founded in soil. - Additionally, the distance between the main dam's

reference monuments and the USC&G Survey monuments'used for horizontal j measurements (4?r miles) can induce a relatively large degree of error compared to

. the accuracy of the annual survey (between the main dam's reference monuments i- and the dam's alignment settlement markers) an_d the Indicated movement over the

! past twenty years. For vertical measurements, the distance between the USC&G monuments and the reference monuments (1!r miles)'also potentially induces a j relatively large error compared to the results of the annual surveys of the alignment

settlement markers.

j' Discussions with Mr. J; C. Lyon,.Jr. of your office indicated agreement that the

distances between the North Anna main dam's reference monuments and the i USC&G _ Survey monuments could induce'slgnificant survey errors which might i

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tend to' mask any actual movement of the dam's alignment settlement markers.  !

Therefore, we propose to discontinue these surveys. _ Relative movement of the

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dam will continue to be monitored annually through the' performance of surveys between the hydroelectric project's reference monuments and the suivey blocks along the main dam. ,

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^ M o'4110295 940405

! 'PDR ADOCK 05ooo338

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l if 'you have any questions, please contact us.

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! Very truly yours, ,

0 ~

J. P. O'Hanlon . .

1 cc: United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555 Docket Nos. 50-338 and 50-339-Ucense Nos. NPF-4 and NPF-7 United States Nuclear Regulatory Commission ,

. Region II - ,

101 Marietta Street, N.W.  ;

- Suite 2900 -

Atlanta, GA 30323 Mr. R. D. McWhorter NRC Senior Resident inspector .

North Anna Power Station i

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