ML19276H583

Prefiled testimony.Auger-Hole Investigation Conducted by Bechtel Did Not Provide Sufficient Evidence Approving or Disapproving Origins of Sediments Deformation

ML19276H583
Person / Time
Site:	Skagit
Issue date:	10/18/1979
From:	Blunden R AFFILIATION NOT ASSIGNED
To:
Shared Package
ML19210E129	List: ML19210E128 ML19276H567 ML19276H572 ML19276H575 ML19276H578 ML19276H580 ML19276H583
References
NUDOCS 7911290450
Download: ML19276H583 (7)

Text

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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICET3ING BOARD In the Matter of )

)

PUGET SOUND POWER & LIGHT ) DOCKET NOS. STN 50-522 COMPANY, et al., ) 50-523

)

)

(Skagit Nucinar Power Project, )

Units 1 and 2) )

)

)

PREFILED TESTIMONY OF ROY BLUNDON October 18, 1979 Q. Would you state your name, address, and occupation, please.

A. Roy H. Blunden, Geologist Urban Environmental Engineering of Coastal Geology 2045 E. Broadway Vancouver, B.C.

Canada 75NIWG My statement of qualifications is on record in :his proceeding.

Q. What documents have you reviewed in preparation f or your testimony?

A. I have reviewed the reports contained in the Report of Geologic Investications in 1978-1979 concerning investi-gation of deformed Pleistocene sediments. Included was a report by Dr. Don T. Easterbrook, dated April 3, 1979.

I have also had a general discussion with Dr. Fred-Pessl, Jr. of the U.S. Geological Survey.

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C. What conclusions have ycu reached?

Tyo specific areas of deformed Pleistocene sediments were considered in the reports, neither cf which have been studied in the field by the writer- Of the two areas referred to in the Bechtel Inc. reports only :he Cavanaugh Road exposures were subjected to sub-surf a:2 investigation and are here considered in the fcilevinc. a..a l.e s i s . This ana_ysis is concernec witn ne expec ations, :in:Ings anc interpretation of th.e i..ve s t ig a t i e r findings cy Ir. Easterbrcok and Sech tel Inc.

Review Of Lake Cavanau:h Ecad Auger-Hele Iny=stiga-ion

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tior cf Pleistocene sediments observable i. road cuts along

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the ".3. Geological Survey ( U.3.G . 5 . who presunably le:ated and reported the occurrence of the deformed materials.

A description of the area of in ze s ti g a t ie r by the L.5.3.5. and by Dr. Easter br oc< indirates the presence of a

-ill orainal ridge t: :he west, ar.d transterse -0 the road, cacked to the east'by lacustrine dep: sits folded into T 'M

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anticline-syncline deformations. Along the inner flank of

ne western anticline, cultiple faults were observed. In addition, flame structures were present in the syncline and inner flar- of the eastern anticline. An auger hole investi-ga tion confu cted by the U .S .G .S . suggested there might be a displacement of underlying glacial deposits on the order of s: e seven re res.

The app aren; intent of the Bechtel Inc. investigation, as suggestad by the data presented, was to determine the cen-inuity cf the sub-surface glacial deposits and, by inference, the presence or absence of faulting associated wi:- the Gi;; iga.- C reek lineation.

Dr. Eis :erbrock ascribes the surface morainal ridge a 7asnon a e and the lacustrine deposits as being of cirilar r e cessiona; .* ashen age . In the same report, howeve r , D r.

Eas:erbr:c' identifies two sub-surf ace glacial sequences en:: ntered . . - auge r holes , the lowermost of which he also as: ices :: ce Of conterporary Vashon age without citing ad diticnal suppor-ing evidence.

ithi. he anger hele logs of Bechtel Inc. (report dated Dece.-ber 29, 1978), the lowermost till of Dr. Easterbr0ok was sual;y re

c;nized and generally described as "Till

t' . . -g ray distict:n, dense to ve ry dense. " S tandard pene: ratio. :es: results indicate that after an initial pene: ratio. cf six ' inches, hamme r blows required to drive l $

T423 \63

the split spoon sampler a further twelve inches (N-value) varied be tween N= 21 & 100+

The mean N-value was 62 blows per foot which tends to confirm the field attribution.

In contrast, Dr. Easterbrook also identified an upper till which in no instance is reported to have been recognized as such in the field. Dr. Easterbrook would appear to have established the existence of the upper till according to the jumping action of the auger bit when gravel and boulders were encountered at an approximately com.on depth within a bedded silty sand sequence. General auger hole log descrip-tions for this ' upper till' are "Siltv Sand: blue-gray, varicusly sorted, scattered gravel and cobbles throughout" occasionally with bedded materials. Logged drilling indica-tions (i.e. the jumping action of the rods) for the same horizon range from small gravel to small boulders. Reported standard penetration values fall between N= 8& 97 The =can N-value was 27 blows per foot, less than half that of the recognized lower till. The two highest V-values, vi:: N= 80 (AH #19) and N = 97 (AH #12) are reported from gravel zones and are therefore spuriously high.

Dr. Easterbook in his analysis of the sub-surface conditions places considerable stress upon the existence of

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the " upper till" to demonstrate that tectonic faulting was not the cause of the soil deformations. The auger-hole logs, in contrast, would suggest that, rather than an irregular till hcrizon e to three me ters in thickness, the " upper till" is the fortuitous assemblage of gravel seams and small bouloers in a bedded silty sand assemblage. Unless Dr. Easterbrook based his identification of the " upper till" upon data not reported ir the quoted sources, it must be concluded that the enistence ci the " upper till" is unproven.

, The continuity of the basal till horizon would appear

c have been confirmed within the limitations of the investi-ga tions. From the data presented, it mu s t be concluded that any single, large displacement of this horizon, suggested by the U.S.G.S., has been shown to be nonexistent. In contras t,

'.cweve r , the assertion by Dr. Easterbrook that the faulted and defor:ned sediments do not persist to significant dep ths belcw road level due to the presence of the " upper till" cannot be substantiated from the investigation findings.

The sub-surf ace investigation also has neither proven nor disproven the existence of recent post-glacial f aulting within the Lake Cavanaugh Road investigation area. Both Dr.

Easterbrook and Bechtel Inc. would appear to have assumed

nat any recent f ault activity would involve the glacial deposics ir easily identifiable vertical dislocations, as cr:ginally suggested by the U.S.G.S. Such reasoning would

_5_

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imply that the absence of dramatic evidence of recog-nizaele disiccatien would nullify any postulated recent faulting along the 3illigan Creek lineation. The form and method of the inves-igatien confirms that only dramatic evidence was sougr.t. Indeed, using the augering methods ado.o t ed , this was the oniv. evidence that could have been identified.

Quaternary f aulting reported near Lake Cushman, Washi..; ton 3.ilson et al. 1979) do offer the dramatic uplif ts of ug to eigh: metres. Examination of the publishec phot: graphs cf test trenches excavated across those f aul s r eve als that had they been investigated using core drilling they would p::bably not have been reccgnized. In the phot ogr aph 'Tigure 2, A p. 237, loc. cit.) an approximately 3-1/2 metre f aul:ed uplif t, had that been core drilled, would . ave yielded i log:

. . - _- A 1 .3 .,

1.1 - Cataclasti: rock

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_ Vitric tuff

.;i:P coring breaks, aten had the lower till seen recovered, the ost probable i..terpretation of such a log would have been a regular till deposit, containing large boulders, overl. ing a puckered rock su rf ace. In a soil formation compcsed of silty sands and tills, s u c.7 as along Lake C ava..a;gh F. ca d , su :P alternating materials would not be iden:ified asevidenceoffaulting.

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t t I .- centrast, slip f aulting with surf ace rupturing associated with the California Galway Lake earthqua:-:e (Hill

E se by , 1977) yielded shear planes which would ce unrecog-izable in any augering investigation. Similarly, in the ab-sence

f information other than the results of drilling in-testigations, such shear planes would be interpreted as soil fissures resulting from dessication, even if advanced sang-1:n? :+chnicues were used.

A critical review of the investigation reports of 3ecnte; :nc. for the Lake Cavanaugh Road Auger-hole study of def orrsd Pleistocene sediments has neither confirned nor fispr:ted a tec enic origin for the features observed. The

rudi:. cf the augering process adopted would be u.-li'<el; to

,* ield ;nequivocable evidence of even dramatic f aulting.

Similarly, the auger-hole investigation has yieldef insuffi-

ien: ei;dence to confirm or disprove alternative origins it: :ne features observed.

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