ML20042C594
| ML20042C594 | |
| Person / Time | |
|---|---|
| Site: | Midland |
| Issue date: | 03/23/1982 |
| From: | Jackie Cook CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Harold Denton Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20042C596 | List: |
| References | |
| 16573, NUDOCS 8203310555 | |
| Download: ML20042C594 (4) | |
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Consumers Power James W Cook 0
00f Vice President - Projects, Engineering and Construction General offices: 1945 West Pernell Road, Jackson, MI 49201 e (517) 788 0453 March 23, 1982 u>
to RECEIVED Harold R Denton, Director 5
MAR 3019825 58 Office of Nuclear Reactor Regulation Nunatasunem US Nuclear Regulatory Commission
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p Washington, DC 20555 MIDLAND PROJECT MIDLAND DOCKET NOS 50-329, 50-330 TEST RESULTS OF THE SOIL BORING AND TESTING PROGRAM FOR THE RETAINING WALLS FILE:
0485.16 SERIAL:
16573 ENCLOSURE:
" TEST RESULTS, RETAINING WALLS, SOIL BORING AND TESTING PROGRAM, MIDLAND PLANT - UNITS 1 AND 2" We are forwarding thirty (30) copies of the enclosed Woodward-Clyde Consultants (WCC) report entitled " Test Results, Retaining Walls, Soil Boring and Testing Program, Midland Plant - Units 1 and 2."
This report describes the scope of the boring and sampling program and the subsequent laboratory testing program for the fill and the foundation materials at the retaining wall areas adjacent to the circulating water and service water intake structures. Detailed supporting data for the triaxial tests are also enclosed. The results of laboratory shear strength and consolidation tests along with related engineering characteristics of the natural soil are discussed below.
GENERAL Three borings (COE-14, COE-15 and COE-15A) were drilled, sampled and logged in the area of the retaining walls.
Boring COE-15 encountered an obstruction at a depth of about 17' from the ground surface, ie, at about Elevation 617'.
This boring was relocated and redrilled as COE-15A.
Samples of fill and foundation materials were obtained from Borings COE-14 and COE-15A.
Approximately 34' of predominantly cohesive fill materials were encountered in Boring COE-14, overlying dense natural sand from about Elevation 600'.
The sand deposit is about 20' thick and is underlain by hard clay beginning at about Elevation 580'.
About 39.5' of stiff to hard cohesive fill and some granular materials were encountered in Boring COE-15A, directly overlying natural hard clay at about Elevation 594.6'.
8203310555 820323 PDR ADOCK 05000329 A
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2 SHEAR STRENGTH PARAMETERS In order to evaluate the shear strength of the_ soil, unconsolidated undrained (UU) and isotropically consolidated-undrained (CIU) shear strength tests on selected undisturbed soil ~ samples, obtained from Borings COE-14 and COE-15A, were performed by WCC. A comparison of the soil shear strenth parameters used in the design of retaining walls and those determined from the tests performed by Woodward-Clyde Consultants (WCC) is indicated below:
t Shear Strength Parameters at Material Foundation Elevations Type Design Values WCC Test Values Natural Soils Sand
$ = 20*, C = 0
$' = 38*, C' = 0 Clay
$ = 0*, C = 2
$' = 36*, C' = 0.2
]
$ = 0*, C = 11.0*
Backfill Soils
$ = 20*, C = 0
$' = 30*, c' = 0.2
- Estimated undrained shear strength corresponding to an overburden pressure of 3.5 ksf.
It can be seen from the above tabulation that the values of shear strength
. parameters used in the design are conservative relative to the values obtained from the recent 1981 WCC tests. Refer to the response to 10 CFR 50.54(f) 4 Question 41 for the design values of shear strength.
HEARING CAPACITY EVALUATION Utilizing the above shear strength paramete rs, the ultimate bearing capacity 1
and the corresponding allowable bearing pressures were calculated. The allowable bearing capacity commitment. made in Subsection 2.5.4.10.1 of the
_ Hidland FSAR requires a factor of safety of 3 for dead ' load plus sustained live loads (static load condition) and a safety factor of 2 for these loads plus seismic loading (seismic. load condition). A comparison.of applied i -
pressures and the allowable bearing pressures obtained from the soil parameters derived from the tests by WCC is presented below:
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3 Estimated Allowable Loading Applied Pressures Bearing Pressures (ksf)
Conditions (ksf)
Based on WCC 1981 Tests Walls Founded on Sand Clay Natural Soils (Elev 595')
(i) Static Load 7.3 9.0 8.7 Conditions (ii) Seismic Load 9.6*
13.5 13.0 Conditions Walls Founded.On Cohesive Fill Fill Soils (Elev 611')
-(i) Static Load 3.3 5.0 Conditions (ii) Seismic Load 4.3*
7.6 Conditions
- Based on sustained loads (DL + LL) plus seismic loads produced by safe shutdown earthquake (SSE).
It can be seen from the above table that the allowable bearing pressures, based on the shear strength values obtained from WCC tests, are higher than the applied pressures under the retaining walls founded on natural soils and backfill soils. Consequently, the design based on the design shear. strength parameters identified in the response to 10 CFR 50.54(f) Question 41 is conse rvative.
WALL STABILITY The issue of the stability of retaining walls under the forces due to steady state seepage was addressed in the meeting with the NRC Staff on May 5-7, 1981 in Bethesda. As discussed in this meeting, the steady state seepage forces would not come into the analysis of the retaining wall stability because the plant site is to be permanently dewatered and no seepage force is expected from plant area fill into the pond.
In the case of steady state seepage from the cooling pond side into the plant area fill, the seepage forces will tend oc0282-0021a100
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4 to increase the resisting forces, thereby, making the retaining walls more stable. Thus, neglecting seepage forces for the proposed operating conditions is a conservative approach.
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JWC/RLT/dsb CC Atomic Safety and Licensing Appeal Board, w/o CBechhoefer, ASLB, w/o MMCherry, Esq, w/o FPCowan, ASLB, w/o RJCook, Midland Resident Inspector, w/o RSDecker, ASLB, w/o SGadler, w/o JHarbour, ASLB, w/o DSHood, NRC, w/a (2)
DFJudd, B&W, w/o JDKane, NRC, w/a FJKelley, Esq, w/o RBLandsman, NRC Region III, w/a WHMarshall, w/o JPMatra, Naval Surface Weapons Center, w/a W0tto, Army Corps of Engineers, w/a WDPaton, Esq, w/o FRinaldi, NRC, w/a HSingh, Army Corps of Engineers, w/a BStamiris, w/o oc0282-0021a100'
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