ML19257A059
| ML19257A059 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 11/29/1979 |
| From: | Gonzales R Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19257A057 | List: |
| References | |
| NUDOCS 8001020016 | |
| Download: ML19257A059 (3) | |
Text
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b. /hoL ENCLOSURE Af.J,. //pc_
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NOV 2 31379 MEMORANDUM FOR:
L. G. Hulman, Chief Hydrology-Meteorology Branch, DSE THRU:
W. S. Bivins, Leader Hydrologic Engineering Section, HMB, DSE FROM:
R. O. Gonzales, Hydraulic Engineer Hydrologic Engineering Section, HMB, DSE
SUBJECT:
TRIP TO THE MIDLAND 1 AND 2 SITE On November 14, 1979, the undersigned, along with Darl Hood, LPM, and representatives of the Corps of Engineers met with the applicant, Consumers Power Company (CPCo) and its engineering consultant, Bechtel, to discuss the work and analyses that have been done since structure settlement problems were encountered in August 1978. This site visit was the initial site tour by the U. S. Army Corps of Engineers, NRC censultant on the soil settlement issue. Enclosure 1 presents a list of attendees J this meeting.
In August 1978, CPCo reported to the NRC resident inspector, R. Cook, that there was larger than expected settlement of the diesel generator building foundation.
Since then, a soils investigation program has revealed that the plant fill under the diesel generator building consists of soft to very stiff clay with pockets of very loose to dense sand.
CPCo's investi-gation has shown that this fill was not adequately compacted. After considering several options to correct the problems, a decision was made by CPCo to preload the diesel generator building with 20 feet of granular material to reduce pore pressure and consolidate the soft areas of clay fill. This fix however, will not significantly improve the quality of loose sands so there is a potential for liquefaction. A permanent dewatering system to remedy this potential liquefaction problem has been proposed by the applicant.
Initially, this system consisted of 200 to 300 submersible deepwells that would extend to the original clay till..At this meeting, we were informed that some pre-liminary pumping tests have shown a very low recharge rate. Consequently, the number of deepwells initially proposed may not be needed. Additionally, the applicant is considering a grout curtain or slurry wall between the power block area and the cooling pond as a measure for reducing the ground water level. The final design will be based on tests that are being under-taken at the present time. Currently, two pumping tests are being conducted; the first in a well that has been drilled in the granular backfi1T between the circulating water conduits, and the second in a well that has been located to test sime deeper sands. The location of the well between the circulating water conduits was selected because the granular backfill may provide the most permeable pathway for groundwater to flow from the cooling pond to 1664 331 O Vo 8
L. G. Hulman.!?! i 0 1979 beneath the power block. This well should define the highest rate of re-charge. The second well which penetrates the deeper sand layers will be used to determine if water seeping from the cooling pond is recharging the groundwater through this deeper granular pathway.
Groundwater recharge rates will be determined from the temporary dewatering system now being installed to dewater the electrical penetration areas and the valve pits. These tests are scheduled to begin in about a month. An injection system will be used in this temporary dewatering to allow any fines, being removed, to be monitored to provide some basis for selection of well filters.
In addition, the temporary dewatering will provide addition-al data about the permeability of the soil.
The tests now being conducted will be used in designing the permanent de-watering system and to demonstrate that the system confonns with section 2.4.13 of the S,tandard Review Plan including Branch Technical Positions HMB/GSB 1.
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.'donzales)HydraulicEngineer Hydrologic Engineering Section Hydrology-Meteorology Branch Division of Site Safety and Environmental Analysis
Enclosure:
As Stated cc: w/ enclosure D. Nuller
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- 1. Hood W. Bivins J. Kane L. Heller R. Jackson lbb4 jj2 R. Gallagher, Region III R. J. Cook - NRC Resident Inspector - Midland Local PDR NRC PDR ACRS (18)
ENCLOSURE 1 Attendees at November 14, 1979 Meeting Midland Plant, Midland, Michigan Tom C. Cooke, Consumers Power Company Project Superintendent Robert G. Wollney, Consumers Power Company Quality Assurance Group Supervisor Al Boos, Bechtel Project Field Engineer Chuck McConnel, Bechtel Engineer Jim 0. Wanzeck, Bechtel Geotechnical Engineer Joe Kubinski, Detroit District Geotechnical Engineer Corps of Engineers Ron Erickson, Detroit District Geologist Corps of Engineers Ron Cook, Nuclear Regulator Comi,ssion Resident Inspector Gene Gallagher, Nuclear Regulatory Commission Region II Inspector Raymond Gonzales, Nuclear Regulatory Comission NRR/DSE/HMB Darl Hood, Nuclear Regulatory Commission NRR/DPM/ LWR #4 1664 333
MEETING
SUMMARY
DISTRIBUTION Docket File NRC POR DEC' 4
Local POR TIC NRR Reading LWR #4 File H. Denton E. Case H. Berkow W. Russell D. Ross D. Vassallo S. Varga J. Stolz R. Baer
- 0. Parr L. Rubenstein C. Heltemes L. Crocker B. Kirschner F. Williams R. Mattson p
R. DeYoung
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Project Manager Attorney, ELD
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LicensingAssistant_Lfy v!///fr/1 IE(3)
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ACRS(16)
R. Denise NRC
Participants:
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1664 334