ML20214G538
| ML20214G538 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 06/26/1972 |
| From: | Mcmullen R US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Gammill W US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| CON-WNP-0121, CON-WNP-121 NUDOCS 8605220260 | |
| Download: ML20214G538 (4) | |
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W. Gaamaill, Calef, Site Analysis Branch, L GEOLOGICAL RECONNAISSANCES TO HANFORD 2 AND GRMD COULEE DA'i, WASHINfTroi, 6-12-72 THRU 6-15-72 Introduction The purposes of the trip were to review the results of the latest inv.ssti -
cations at tae ilanford 2 site, exa-1 se the 15 foot deep trench recently excavated across the proposed site of the reactor building, and to conduct a geological reconnaissaace of the region around Grand Coulee Dme.
Itinford 2 on 13 June tne U",03 represoutativea and I were accot;panied by representa-tives f row VPPS'i, burim and Moe, and Shannon and Wilson to tie nanford 2 mite.
Tae trenca acrosa the reactor site is 15 feet deep by about 203 feet lont,.
Tae sides of tae trenca had raveled so badly that it was inmossible to see the stratigraphy. We were able to clean off the sides at several locations and thun spot-check exposurca. The uaper tuo feet of soil (a sandy nilt), wnich is probably of about the ears guologic age as tne Touchet beda in thu FFTF area, was axposed and shovel ne indica-tions of being displaced. Beneath the silt was a two to five foot thick layer of gravel w;iica did not appear to be displace 1.
At one end of the trenc's enere were several filled-in cavitien eatendinr several feet into tan gravel layer. These featurca were attributed to anical burrowinr3 I
watch werei obviously older than the overlying silt bed.
Thore were no offsets on either side of these featuren. Lelen the travel layer was a coarne to nedlun grained asnd which es. tended at least to the base of the trench. Tae sand was very loose and caved incediately af ter dir,ging into it.
It van igossible to deteriaine orientations of bedding or whether or not this caterial and been displaced by faultint,. Tac Shannan and Wilson representative stated that detailed photographs had been taken irmediately after each section of wall was exposed, and that detailed mapping was accouplished. These documents will be provided as soon an available. Relative density tests made within the wpper 1$ feet of soil, wuica we had requented earlier in order to confirm the results of standard penetration tests, indicateed that the parameters based on I
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6 W. Cammill the standard penetration testa taken during subourface investigations were easipistely inaccurate (actually 40 to 50% average relative density instead of the computed 75% minimiss). urFSS and consultants had not yet decided what course of action to take, but were considering excavating to the top of the 11agold formation (about 40' depth) and backfilling and eenpastiwd up to the feendation grades. They were told that they saast assure us that the material below 40 foot depth met the criteria of 75% minimum relative density. The asse method of determining rela-tive densities above 40' depth was employed to compute relative densities of the material below this level; therefore, the competency of the deeper soil is questionable. However, seismic refraction data indicate that there are sharp increases in compression wave velocities below this level, indicating a more dense material. I told them that they must substantiate the relative density values derived from the standard penetration blow counts below a depth of 40 feet by some means other than the seismic refraction data.
I again explained our reasons for requiring the boring into bedrock as follows:
1.
to confirm the results of the geophysical surveys which, when used alone, can be misleading; 2.
to aid in defining the structural geology beneath the site and its relationship to the regional geology to confirm along with the other data that there is no geologic structure that could be of greater significance to the site as an earthquake generator than the Rattlesnake Wallula structure.
Crand Coulee
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On the afternoon of June 13 we traveled to Grand Coulae. A list of attendees for the geologic reconnaissance is attached.
Messrs. Viers and Neff of the Bureau of Recismation took us to the terrace esposures along the Columbia River north of Grand Coulee and pointed out the location at which the dated sample mestiemed in the Blume report was takaa. It had been reasoned that einee material similar to this overlay the Colville Fault in an undisturbed state, the last movement alees the I
fault was at least older than this materiel. The test indicated that the i
soil, which belsaged to the Nespellum formation, was at least 27,400 years old. Our ariteria for determining that a fault is inactive require ' that it be desmastrated that movement along that fault has not occurred la less than 35,000 years. Additionally, the Nespellum formation is apparently a
" catchall" formation which contains a conglomeration of material deposited between the beginning of Pleistocese (one million vaars aco) and -
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W. Caama111 We next traveled up to the south "end" of the westernmost fault af the Colville fault some (Republic Craben). On receansitaring this area, we used the USGS geology quadrangle may based on the work of M. Staats.
The map sheys that this portion of the fault transacts the Neapellum formation. It could possibly be a printing error as the fault line coincides with a conteur line and may have been mistakenly blacked in instead of dashed. The dashed line would indicate that the fault lay under the soil but did not displace it, thus providing proof that move-mest had not taken place since deposition. Bob Norris of the USGS will contact Staats to determine whether er met the fault does in fact dis-place the Nespellum formation. We located in the field, with some difficulty, the exposures shown on the map, but were unable to determine the location of the fault trace.
The geological reconnaissance to Grand Coulee did not alter the conclu-sions stated in our preliminary report dated 9 June 1972. In this report it was stated that the applicant had not adequately demonstrated the conservatism of its proposed SSE and OBE acceleration values of.16 and.08, respectively. The age of last movements along the. Colville faults reust be determined, and the limits of the southern extension of the fault must be established, particularly if the age of last movement is indeterminate or is r.arginal by AEC criteria.
DICTE IP"TIO]
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- 1. B. McMullen, Geologist EAB - Edg Site Analysis Branch Directorate of Licensing cc S. Miner, L J. Shea, L Note: On 21 June, Mr. Morris, USGS, called and stated that the solid line denoting surface faulting was a printing error.
Mr. Staats had cesfirmed that the fault did not offset the Neapellum forma-tion.
Mr. Staats had also expressed his belief that the graben is continuous across the Columbia River, downstrema from Grand i
l Coulee Dam, and that the Faults were formed eencurrently with the resurgent phase of intrusive igneous activity within the Colville Batholith. This event occurred la Late Miocene, or more than 25 million years ago. It is still up to the appli-cant to demonstrate that the Colville Fault Zone is inactive by AEC criterie.
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