ML19290C592

Forwards Questions & Requests for Addl Info Resulting from Applicant Repts & 791026 Discussions.Info Re Migrated Profiles Not Received to Date

ML19290C592
Person / Time
Site:	Skagit
Issue date:	12/10/1979
From:	Devine J INTERIOR, DEPT. OF
To:	Rolonda Jackson Office of Nuclear Reactor Regulation
Shared Package
ML19290C542	List: ML19290C583 ML19290C592
References
NUDOCS 8001220132
Download: ML19290C592 (6)

Text

.

, .. s lix.

'- L : g, ~,

': ' e 's-n United States Department of the Interior

q. .

. q [. ;QJp [.I GEOLOGICAL SURVEY ,

%. RESTON. VA. 22092 In Reply Refer To: giA 3 ",j Mail Stop 905 December 10, 1979 b

Dr. Robert Jackson Division of Site Safety and Environmental Analysis Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Ccmmission Washington, D.C. 20555

Dear Bob:

Transmitted heresith are questions and requests for additional information regarding the Skagit Nuclear Power Project. These questions have resulted from our review of the reports recently submitted by Puget Pcuer and their consultants and from the discussion during our Bethesda meeting October 26, 1979. ,

The questions regarding marine profiles refer to specific features but, as you cay rccall, at the October coeting we also requested copies of the migrated profiles. "cne of these have been received to date. You may wish to remint' Fuget Pc.wr of this oversight.

Sincerely yours,

_ & u ,'- A 3

Jan.es F. Devine Deputy for Engineering Office of Earthquake Studies 0"" ' ', 4<.'

(.' .s

[ }. One Hw: dred Ycars of Earth Science in the Public Service

.- c y..4 1788 060 s oomog3 4

, REQUESTS FOR ADDITIONAL INFORMATION PUGEl SOUND POWER AND LIGHT COMPANY

. . SKAGIT NUCLEAR POWER PROJECT, DOCKET NOS. STN 50-522/523 Castions:

1

1. In view of the recent acknowledgement by consultants to the applicant that (323.86) the contact between the Chuckanut Formation and the Shuksan Petamrphics is a high-angle fault where it crosses Loretta Creek (conference in Bethesda, Maryland, October 26, 1979) and of increased concern regarding the likelihood of high-angle faults elsewhere in the site region, the applicant should investigate in detail the possibility that all or some of the movement evidenced by shearing at and near the Chuckanut-Shuktan contact in drill holes and trenches northeast of the proposed Category I structures was produced by a fairly high-angle fault that is younger than the principal folding of the Chuckanut Formation and is not fundsaatally related to the basal contact of that formation. Such a fault ui 9ht form the contact of the Chuckanut only locally and at shallow dcpth and be entirely within the older rocks else.there.

In planning an investigation that will establish or preclude such an interpretation of shearing along and near the Chuckanut contact at the .

plant site, the applicant night consider, but not limit its thinking to, the following studies:

a. Determination, northeast of the proposed Category I structures, of the precise location and dip of the Chuckanut-Shuksan contact and any faulting in its vicinity, from the surface to an appropriate depth.

b. Excavation, for inspecticn and mapping, of an exposure of the contact and the bedrock on both sides that is of such size and character that the abser.ce or presence of faulting can be incontrovertibly demnstrated.

c. "uch reore detailed investigation and mapping of the geology in the vicinity of the Chuckanut-Shuksan contact, in the northwestern part of the site area and between the site area and the Samish River.

2. 'The applicant (RGI, Appendix H, sheet 1) maps an almost-continuous strip of glacial deposits along the south edge of the Skagit River valley, from (323.87) several miles west of Gilligan Creek eastward across Gilligan, Day, and Loretta Creeks to Cumberland Creek. In view of the recognition of faulting in 1caer Loretta Crcek valley by 1:hetten and others (1979) and, later, by the applicant, and of concern regarding high-angle faulting east '

of Gilligan Creek and possibly elsewhere in the region, the applicant's discussion of possible deformation of Quaternary deposits, in resper.se to NRC Request 323.84 is inadequate. There is no analysis of terrace surfaces on the glacial and younger deposits along the south side of the Skagit River valley, and no nap differentiation of the glacial deposits nor of the lateral extent of the units described within the glacial deposits (RGI, p. 3.2-5). Finally, there is no discussion of the structural control that features of these types may provide by their distributions and elevations. The applicant should correct these deficiencies, and, similarly, it should consider and, if desirabl>, carry out further Quaternary studies on the north side of the Skagit River valley. The applicant should substantiate, if possible, its 1

1788 061

interpretation of the Quaternary deposits around the mouth of Gilligan I Creek as being older than Fraser Glaciation and its suggestion that a till deposit there may be of Salmon Springs age. .

3. In view of recent recognition of the existence of additional marine (323.88) seismic profiles within and north of the San Juan Islands (the 1971 lines of Western Geophysical Corp.) and the need for integrating interpretations of the various sets of marine profiles, the applicant should provide (1) a map showing all seismic profiles in the southern Strait of Georgia-San Juan Islands-northern Puget Sound region and all tectonic structures that are or might reasonably be inferred from study of the profiler, and (2) the approximate " shot-point" locations of the intercepts of the structures with the profiles.

4. The applicant should clarify the following discrepancies in Appendix A of (323.89) the RGI:

a. Regarding figure 5 (also referred to as " Area B" and " Sheet 2A"): It -

is indicated in this figure that the flight lines were north-south, while Appendix 3 indicates that they were east-west.

b. Regarding figure 6 (also referred to as " Area E" and " Sheet 5"): It is indicated in this figure, in figure 1, and in the text that the lines were flown at 4,500 ft, barometric, while Appendix 3 states that they were flown at 2,500 ft, barometric.

c. ":garding figure 7 (also referred to as " Area F" and " Sheet 6"): It is indicated in this figure, in figure 1, and in the text that the lines were ficwn at 2,500 ft, barometric, while Appendix 3 states that they were flown at 4,500 tt, barometric.

d. In the report by M. E. Beck, Jr., that is included in Appendix A of the RGI, what are the meanings of declinations greater than 360 s degrees?

5. Because present d3ta are inadequate in helping to define the attitude of (323.90) the controversial Haystack-Shuksan thrust fault, the applicant should considar providing other geophysical data to resolve the question.

6. Concern regardir.g the extent and location of the "Loveseth fault" .

(323.91) northwest of section 3, T. 33 N., R. 5 E. (approximately located but interpreted as normal contact in RGI, Appendix H, sheet 1) and of the

" Table Mountain fault" northwest of the Table Mountain vicinity (Whetten, Dethier, and Carroll,1979, near southwest corner of maps) and ongoing mapping by USGS geologists in the region prompt the following requests for more information regarding the Walker Valley-Clear Lake vicinity:

a. Explain basis for moving the Chuckanut exposure shown in center of section 33, T. 34 N. , R. 5 E. in 1978 version of regional geologic map (Exhibit 132; 1:62,500 scale) to a position farther southwest in the same section (RGI, Appendix H, sheet 1) and evaluate more fully the mapping of a faulted Chuckanut contact, at or near the earlier map location, by Jenkins (1924), Loveseth (1975), Stoker (1977), and Whetten, Dethier, and Carroll (in press).

2 1788 052

b. Pr ovide the basis for mapping (RGI, Appendix H. sheet 1) the entire exposure of rock along the boundary between sections 29 and 30, T. 34 I N., R. 5 E., as Chucknut and the exposures in the northeast 1/4 of section 32 as " Church Mountain Plate"; and evaluate, in more detail, the possibility of a northwest-bearing fault contact in this vicinity, as pro press) posed by Jenkins (1924) and Whatten, Dethier, and Carrol

c. Describe and explain the relationship of th'e Chuckanut Formation to the " Church Mountain Plate" at Big Rock (Sec. 23. T34N, R4E) and evaluate the statement by Stoker (1979) that there are deformed lake sediments in that vicinity.

d. Explain more adequately why the contact of the Shuksan metamorphic rocks between the Table Mountain vicinity and Mundt Creek, to the northwest, should not be considered to be a high-angle fault zone.

e. Describe all bedrock exposed in the hill immediately west of Clear

• Lake and the hill immediately southwest of Beaver Lake, T. 34 N.,

R. 4-5 E., and explain why these hills are assigned to the "Shuksan Thrust Plate".

f. Provide the basis for mapping (RGI, Append. H, sheet 1) the exposure of rock near the center of Section 3 T33N, R5E as part of the " Church Mt. Plate".

7. The applicant should explain more fully the Sackung-like features on Cole

!Muntain near the Loretta Creek " fault" which were interpreted as caused (323.92) solely by " gravitational forces" when similar features elsewhere are interpreted to indicate recent movement on faults near to the features.

8. Please provide a discussion as to the reasons why older nonglacial (323.93) deposits appear to occur only west of the mouth of Gilligan Creek.

9. Please discuss the impact of the Loretta Creek fault, now recognized by (323.94) the applicant to exist, on the interpretation of the regional tectonics since such a fault does not appear to be part of the thrust plate as is the applicant's interpretation of the southern portion of the Gilligan fault.

1788 063 3

References cited I

Jenkins, 0. P.,1924, Geological investigation of the coal fields of Skagit County, Washington: Washington State Division of Geology Bulletia 29.

Loveseth, T. P. ,1975, The Devils Mountain Fault Zone, northwes!.arn Washington: University of Washington Masters thesis.

Stoker, B. A., 1977, Assessment of need for geologic mapping in the Clear Lake quadrangle, Washington: Unpublished report received from Roger Leed, August 8, 1977.

Stoker, B. A. ,1979, Prefiled testimony before the ASLB dated October 18, 1979, page 8.

Whetten, J. T. , Dethier, D. P., and Carroll, P. R. ,1979, Preliminary geologic map of the Clear Lake NE Quadrdangle, Skagit County, Washington: U.S.

Geological Survey Open-File Report 79-1468. .

Whetten, J. T., Dethier, D. P., and Carroll, P. R., Preliminary Geologic map of the Clear Lake NW Quadrangle, Skagit County, Washington, in press.

1788 064 4

s .

323.95 Provide appropriate discussion of all the reasonably inferred tectonic structures identified in response to question 323.88. Your response should include but is not limited to (1) the probable age (s) of the tectoric structures and (2) how these structures fit into the framework of regional tectonics.

1788 065 5