ML20198G522

Forwards LWA Testimony Re Geological Seismological & Foundation Engineering Aspects of Site.Investigations Adequate to Define Properties of Foundation Soils.Parameters Used in Design of Foundations Appropriate

ML20198G522
Person / Time
Site:	Washington Public Power Supply System
Issue date:	03/12/1975
From:	Harold Denton Office of Nuclear Reactor Regulation
To:	Moore V US ATOMIC ENERGY COMMISSION (AEC)
References
CON-WNP-1053 NUDOCS 8605290646
Download: ML20198G522 (8)

Text

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DISTRIBUTION:.

. MAR 121975 4

DOCKET FILES NRR-RDG SAB V. A. Moore, Assistant Director for LWR's l

LWA - SEISHOLOGY AND GEOLOGY POUNDATION ENGINEERING i

PLANT NAME: WPPSS 1 & 4 LICE 9iSING STAGE: CP DOCK.:Cf NUMBER: 50 M 513 RESPONSIBLE BRANCH: LWR 2-3 RECdESTED COMPLETION DATE: February 28, 1975 i

APPLICANTS RESPONSE DATE NECESSARY POR NEXT ACTION PLANNED ON PROJECT: None DESCRIPTION OF RESPONSE: N/A REVIEW STA'IUS: CP Enclosed is our LWA Testimony regarding the geological, seismological, and foundation engineering aspects of the Hanford site. The report was i

prepared by Dr. L. Heller, S. Coplan, & R. McMullen of the Site Analysis Branch.

I W Rfted by

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Harold R. Denton, Assistant Director for Site Safety Division of Technical Review Office of Nuclear Reactor Regulation

Enclosure:

As Stated ces w/o encl:

A. Giambusso W. Mcdonald J. Pansarella ces w/enel S. Banauer J. Carter F. Schroeder

8. Varga H. Denton R. Morris, USGS SS Branch Chiefs S. Brocknen. USGS LC4W A. Schwencer G. FranhHn, C of E t/

I T. Cox R. McMullen R. Elecker SEE PREVIOUS YELLOW FOR CONCURRENCE 8605290646 750312 PDR ADOCK 05000460 L

PDR

DISTRIBUTION:

}

D CKET FILES

-Rdg SAB V. A.

re, Assistant Director for LWR's LWA - SEI LOGT AND GEOLOGY FOUNDATION ENGINERnTNG j

PLANT NAME:

SS 1 & 4 LICENSING

CP DOCERT NUMBER:

0-400/513 l

RE9PONSIBLE BRAN : LWR 2-3 REQUESTED COMPLETI DATE: February 25, 1975 i

AFFLICANTS RESPONSE TE NECESSARY FOR NIET ACTION PLANNED N PROJECT: None DESCRIPTION OF RESPONS N/A REVIEW STAIUS: CP l

Enclosed is our LWA Testi regarding the geological, seismological, j

and foundation engineering a acts of the Hanford site. The report was j

prepared by Dr. L. Heller, S.

plan & R. McMullen of the Site Analysis Branch.

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Haro R. Denton, Assistant Director for te Safety Divisier of Technical Review Office of Tuclear Reactor Regulation l

Enclosures l

As Stated l

cc: w/o enc 1:

A. Giambusso W. Mcdonald J. Pansarella j

i ces w/enel:

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l S. Hanauer J. Carter

. ;;da Hendrie S. Varga H. Denton R. Morris, USGS SS Branch Chiefs S. Brockman, USGS l

i A. Schwencer G. Franirlin, C of E T. Cox R. McMullen R. Elecker I

I D. Eisenhut i

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R55 n g SCoplan * # NStepp "Usiiier

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1' Forum A&C 318 (Rev. P-53) ABCM 0240 1'r u. s. eovsanuans pasurine orricas eore.sae-see

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WPPSS NUCLEAR PROJECT - UNITS 1 AND 4

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LWA TESTIMONY

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CEOLOGY, SEISHOLOGY, AND FOUNDATION ENGINEERING J

The WPPSS Nuclear Project No.1 site is located on the AEC Hanford Reservation, which is within the Pasco Basin, a physiographic and tectonic subdivision of the,dolumbia River Plateau Physiographic v

j Province and the Columbia River' Tectonic Provice respectively. The Pasco Basin is bordered on the north by Saddle Mountain; on the west by the Yakima and Umtanum Ridges; and the southwest and south by the Rattlesnake Hills and the Horse Heaven Hills. These features are

' antic 11nal folds within the upper basalt flow units. The eastern boundary is formed by the White Bluffs, which locally is the east.

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bank of the Columbia River. Topographic relief in the Pasco Basin varies from mav4== elevations exceeding 3,500 feet atop Rattlesnake l}

Mountain to a minimum elevation of +340 in the Columbia River channel at Richland where the river flows out of the Basin. The site lies at h

I elevation +445 on flat terrain that slopes gently to the northeast about 2 1/2 miles west of Columbia River.

The Pasco Basin has under-l gone continuous subsidence relative to the Columbia River Plateau since its formation which began with volcanic activity in early Miocene.

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l Several anticlinas including the Umtanum Ridge-Gable Mountain-Gable Butte complex, and Saddle Mountain, are faulted. The faults, where

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1 identifiable, are high angle thrust faults of limited extent which originated where folding was inadequate to relieve the regional stresses.

Some normal faulting has also been identified in the region.

The faults parallel the anticlinal structures and are generally found on the north, overturned side, however, some such as the thrust fault on the Gable Mountain anticline are subparallel and cut across the fold axis. Most of the faults are at least older than late Pleistocene.

Bingham et. al. (1970) determined that the faults on_ Gable Mountain Anticline are probably more than 100,000 years old. Faults within the Pasco Basin are associated with steeply overturned assymetrical anti-clines. The applicant has demonstrated, both in geological investiga-tions for WPPSS-2 and for this investigation that there are no sharply assymetrical anticlines or other geological structures that could localize earthquakes in the immediate site vicinity, or that could cause surface displacement at the site.

The largest geologic structure of significance to the site is represented by the Rattlesnake-Wallula lineament. The lineament tre.nds northwest -

southeast and borders tHe Pasco Basin on the southwest and south. It is about 80 miles long and is located 13 miles southwest of the site.

The lineament is a belt of en-echelon, doubly plunging antic 11nes com-prising the Rattlesnake Hills anticline to the west and the Wallula Gap fault zone to the east. Faulting associated with the Rattlesnake-Wallula lineament and other mapped faults around and within the Pasco 3

Basin, appear to be related to near surface folding that occurred contemporaneous 1y with the downwarping of the Columbia River Plateau e

and the Pasco Bas _a.

Thus, this structure is not Akely to be directly related to basement structure nor is it apt to be continuously faulted along its entire length. We have concluded that the Rattlesnake-Walluia lineament is the most significant structure for determination of the safe shutdown earthquake.

The site is mantled by 10 feet or less of aeolian deposits overlying 50 to 90 feet of Pasco gravels. The glacio-fluvial Pasco gravels consist primarily of medium dense co very dense gravelly sands. Beneath the i

Pasco gravels is the Ringold formation, which is composed of three units:

an upper weakly indurated siltstone and sandstone, a middle conglomerate member, and a lower siltstone and claystone member. The upper unit is absent in the site area and the Category 1 foundations will be founded either directly on the conglomerate or on engineered backfill on the i

conglomerate. The Ringold extends to a depth of about 480 feet. Beneath the Ringold are at least 5,000 feet of basalt flows and tuffaceous inter-beds.

Historical seismicity within the Columbia Basin Tectonic Province indicates that the province is characterized by the infrequent occurrence of low -

to moderate intensity earthquakes. The largest event had a maximum intensity of VII and occurred in the Milton-Freewater area of northern Oregon in 1936.

Several smaller events are also geographically clustered in the same area about sixty miles from the site. A second cluster near Ellen-burg, Washington consists only of smaller events. The remaining earth-quakes have been geographically scattered through the province, the l

l largest being an intensity VI-VII event which occurred near Umatilla l

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Oregon in 1893. We consider it possible that similar earthquakes could occur anywhere in the province.

By virtue of its extent and proximity to the site, the Rattlesnake-Wallula lineament must be considered to be the greatest potential generator of earthquakes of significance to the site. It appears likely that the intensity VII 1936 Milton-Freewater event was associated with this structure.

The SSE for the WPPSS site is based on the following:

1)

The maximum random earthquake in the Columbia Basin Tectonic Province will be no greater than intensity VII and can result in that intensity at the site; 2)

The Rattlesnake - Wallula'11neament represents the most signi-ficant seismically active structure. We view it as having the potential of generating earthquakes of intensity VIII at a distance of little more than 10 miles from the site.

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Based on the above, we have concluded that an intensity of VII-VIII is a conservative site intensity for representing the SEE. Thus we consider a horizontal acceleration of 0.25g used as the zero period 1Lnit of l

appropriate response spectra to be a conservative SSE. This acceleration I

is to be applied at the foundations of Category I structures. Under AppendixAto10CFRPart100,weconsideravalueof0.125g(equal.to-one halfoftheSSE)tobeaconservativeOperatingBasisEarthquake.

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The applicant plans to excavate to a depth of about 60 feet and recompact the material to an 85% average relative density in zones that support or influence Category 1 foundations. The applicant has demonstrated that the proposed fill material will have an adequate resistance to liquefaction, due to the postulated earthquake, when compacted to a relative density of f

75 per cent. The applicant's proposed specification for the Category I fill, 85 per cent average relative density, no more than 10 per cent of i

the fill below 85 per cent relative density, and a minimum of 75 per cent i

relative density, will assure the stability of supported Category I structures subjected to the postulated earthquake. The sandy gravel, silt, and clay below a depth of 60 feet are dense and well consolidated, and will provide competent support for Category I structures.

The applicant has requested a limited work authorization.to excavate for s

Category I structures (containment and general services building). The I

excavation will be made down to the bearing horizon (conglomerate member l

of the Ringold Formation). Density tests will be made within the conglomerate, i

i and any pockets of insufficiently dense material will be removed and replaced with compacted backfill. All structural backfill will be placed according to the proposed specifications stated above.

We conclude that investigations have been adequate to define the properties of foundation soils, and that the methods and parameters used in the l

design of foundations are appropriate and conservative.

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REFERENCES 1.

Bingham, J. W., Londquist, C. L.,

and Beltz, E. H., 1970, " Geologic Investigation of Faulting-in the Hanford Region, Washington,"

U.S. Geological Survey Open File Report.

2.

Newcomb, R.

C., 1970, " Tectonic Structure of the Main Part of the Basalt of the Columbia River Group, Washington, Oregon, and Idaho."

U.S. Geological Survey, Misc. Geol. Invest. Map'I - 587.

3.

U.S. AEC, 1972, " Safety Evaluation of The Hanford No. 2 Nuclear.

Power Plant," Docket No. 50-397.

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