Calculation 09-4179.01-F18, "Slope Stability Analysis"

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By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 1 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

ATG - Azekah T. Griffiths JW - Jui-Pin Wang

TABLE OF CONTENTS

1 Purpose 4 2 References 4 3 Methodology 4 4 Analysis 6 5 Results 30 6 Conclusion 31 Appendix

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By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 2 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. _0_9_-_41_7_9_.0_1__ ------

LIST OF FIGURES

Figure 1 - Location of Cross-sections for Slope Stability Analysis 7 Figure 2 - (2.5-160 Cross-sections in Powerblock Area) 8 Figure 3 - (2.5-161 Cross-sections in Intake Area and Utility Corridor) 9 Figure 4 - Location of Excavation Cross-sections in CCNPP Unit 3 11 Figure 5 - Excavation Cross-sections in CCNPP Unit 3 11 Figure 6 - Critical Slip Surface for Section A- Case a - Static - ESA 16 Figure 7 - Critical Slip Surface for Section A- Case a - Pseudo-static - TSA 17 Figure 8 - Critical Slip Surface for Section A- Case a - Pseudo-static - ESA 17 Figure 9 - Critical Slip Surface for Section A- Case b - Static - ESA 18 Figure 10 - Critical Slip Surface for Section A- Case b - Pseudo-static - TSA 18 Figure 11- Critical Slip Surface for Section A- Case b - Pseudo-static - ESA 19 Figure 12 - Critical Slip Surface for Section B- Case a - Static - ESA 20 Figure 13 - Critical Slip Surface for Section B- Case a - Pseudo-static - TSA 20 Figure 14 - Critical Slip Surface for Section B- Case a - Pseudo-static - ESA 20 Figure 15 - Critical Slip Surface for Section B- Case b - Static -ESA 21 Figure 16 - Critical Slip Surface for Section B- Case b - Pseudo-static - TSA 21 Figure 17 - Critical Slip Surface for Section B- Case b - Pseudo-static - ESA 22 Figure 18 - Critical Slip Surface for Section C- Static - ESA 23 Figure 19 - Critical Slip Surface for Section C- Pseudo-static - TSA 23 Figure 20 - Critical Slip Surface for Section C- Pseudo-static - ESA 23 Figure 21- Critical Slip Surface for Section D- Static - ESA 24 Figure 22 - Critical Slip Surface for Section D- Pseudo-static - TSA 24 Figure 23 - Critical Slip Surface for Section D- Pseudo-static - ESA 25 Figure 24 - Critical Slip Surface for Section E- Static - ESA 25 Figure 25 - Critical Slip Surface for Section E- Pseudo-static - TSA 26 Figure 26 - Critical Slip Surface for Section E- Pseudo-static - ESA 26 Figure 27 - Critical Slip Surface for Section F- Static - ESA 27 Figure 28 - Critical Slip Surface for Section F- Pseudo-static - TSA 27 Figure 29 - Critical Slip Surface for Section F- Pseudo-static - ESA 28 Figure 30 - Critical Slip Surface for Section G- Static - ESA 29 Figure 31- Critical Slip Surface for Section G- TSA 29 Figure 32 - Critical Slip Surface for Section G- Pseudo-static - ESA 30

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 3 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

LIST OF TABLES

Table 1 - Inertial Effect Coefficients 12 Table 2 - Material Properties for Powerblock 13 Table 3 - Material Properties for Intake Area 14 Table 4 - Material Properties for Utility Corridor 15 Table 5 - Computed FOS for Section A- Case a 16 Table 6 - Computed FOS for Section A- Case b 17 Table 7 - Computed FOS for Section B- Case a 19 Table 8 - Computed FOS for Section B- Case b 21 Table 9 - Computed FOS for Section C 22 Table 10 - Computed FOS for Section D 24 Table 11- Computed FOS for Section E 25 Table 12 - Computed FOS for Section F 26 Table 13 - Computed FOS for Section G 28 Table 14 - Summary of Factors of Safety - Static Analysis 30 Table 15 - Summary of Factors of Safety - Pseudo-static Analysis 31

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 4 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

1 PURPOSE

To determine the stability of slopes and their potential impact on safety-related structures at the Calvert Cliffs NPP Unit 3 Site.

2 REFERENCES

a) Duncan, J. D. (1996). "State of the Art: Limit Equilibrium and Finite-Element Analysis of Slopes," Journal of Geotechnical Engineering, ASCE, Vol. 122, No.7, pp. 577-596.

b) GEO-SLOPE, Stability Modeling with SLOPE/W 2007: An Engineering Methodology, Second Edition, May 2007, Geo-slope/W International Ltd.

c) Mactec Engineering and Consulting, Inc. (Mactec), (2009). Structural Fill Static Laboratory Testing Results, Rev. 5, Project No. 6234-08-4783, Charlotte, NC.

d) UniStar Nuclear Services, LLC. (UniStar), (2009). "Stability of Subsurface Materials and Foundations," Geology, Seismology, and Geotechnical Engineering, Rev. 5, FSAR 2.5., pp. 1286-1552.

e) Paul C. Rizzo Associates, Inc. (RIZZO), (2009a). 09-4179.01-F16 "Triaxial Compression & Direct Shear Testing"

f) Paul C. Rizzo Associates, Inc. (RIZZO), (2009b). 09-4179.01-F9 "Soil Strata - Thicknesses and Termination Elevations"

g) Paul C. Rizzo Associates, Inc. (RIZZO), (2009c). 09-4179.01-F13 "Unit Weight"

h) Paul C. Rizzo Associates, Inc. (RIZZO), (2009d). 09-4179.01-F17 "Undrained Shear Strength"

3 METHODOLOGY

The stability of the proposed constructed slopes was evaluated using the SLOPE/W computer program (GEO-SLOPE, 2007). Two dimensional models of various cross-sections across the CCNPP Unit 3 site were created to calculate the Factor of Safety (FOS) against failure at each slope. In SLOPE/W, factors of safety against slope failure are computed using the method of slices considering a limit equilibrium approach. A Mohr-Coulomb failure criterion is used to calculate the shear strength along the failure surface. This relationship is given by:

T = C + (J tan ep where c = cohesion,

(J = normal stress

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 5 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

cj) = angle of internal friction. Various limit equilibrium methods are available for slope stability evaluation, including the Ordinary method (Fellenius 1936), Bishop's simplified method (Bishop 1955), Janbu's simplified method, (Janbu 1968), and Morgenstern-Price method (Morgenstern 1965). These methods were selected for evaluation of slopes because they are routinely used, and their limitations and advantages are well documented. The main differences are:

• Static equilibrium equations, • Interslice forces that are included in the analysis, • Assumed relationship between the interslice shear and normal forces.

In this analysis the following methods are considered: Ordinary method (Fellenius 1936), Bishop's simplified method (Bishop 1955) and Morgenstern-Price method (Morgenstern 1965). SLOPE/W has been validated and verified for the three methods by RIZZO.

Two types of analyses were performed in this calculation: static and dynamic analysis.

In the static analysis, a Mohr-Coulomb failure criterion based on effective stress conditions was used. For the sand layers, it is assumed that the effective cohesion, c', is equal to zero. This is a conservative approach which yields a lower factor of safety (FOS). The sand layers at the site contain varying amounts of clay and silt as shown in the boring logs for the site. The effective friction angle (

In the dynamic analysis, a pseudo-static approach was performed, which represents the effects of seismic activity by acceleration that creates inertial forces. These forces act in the horizontal and vertical directions at the centroid of each slice, and are defined as:

where ahand ay are horizontal and vertical ground accelerations, respectively, W is the slice weight, and g is the gravitational acceleration constant. The inertial effect is specified by khand k y coefficients, based on the site seismic considerations. Two cases were considered for the dynamic analysis: 1) A Mohr-Coulomb failure criterion based on total stress conditions was used, to account for the hydrostatic pressure buildup. For the sand layers, total strength parameters (cohesion, c, and friction angle,

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 6 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. _0_9_-_41_7_9_.0_1__ ------

Various runs were conducted on each slope to determine the lowest factor of safety. Sloughing or surficial failures that appeared during analysis were evaluated and disregarded when appropriate.

Note that in this calculation, TSA and ESA represent total stress analysis and effective stress analysis, respectively.

4 ANALYSIS Cross-Sections

The location of each of the cross-section analyzed is shown in Figure 1. Both figures were based on Figures 2.5-159 through 2.5-161 (UniStar 2009) of the CCNPP3 FSAR. Note that Section F shown in Figures 2.5-170 and 2.5-176 (UniStar 2009) is not consistent with cross-section shown in Figure 2.5-160 (UniStar 2009), which shows the slope for Section F as negligible. Therefore, this section is not considered in this analysis. Section H in Figure 2.5-161 (UniStar 2009) is renamed as Section F for this analysis.

Seven cross-sections are considered in this analysis (See Figure 1.) Sections A, C, D and E are located in the Unit 3 area, and Section B in the Construction Layout Area (CLA). For this analysis, Sections A through E is treated as the powerblock area. The cross-sections in the powerblock area are shown in Figure 2. Section F extends across the Utility Corridor, and Section G extends across the Intake Slope and Intake area. Sections F and G are shown in Figure 3.

Figures 4 and 5 show the location and the relative positions of safety-related structures to slopes in Sections A', G' and Gil for the powerblock and the intake area. Surcharge loading was excluded from the analyses because the proposed structures are sufficiently set back from edges of slopes.

The thickness of each soil layer is determined using the borings located in the vicinity of each cross-section (See RIZZO 2009b).

For this analysis, the properties of the subsurface materials for the Unit 3 and CLA areas are combined and treated as the powerblock. The Intake Slope and Intake areas are referred to as the Intake Area. No laboratory data were available for the Utility Corridor. However, due to the close proximity of the utility corridor to the powerblock, the properties of the soil beneath the powerblock are used for the utility corridor.

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 7 of 31 Subject: v"'By: Date: _ Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01

FIGURE2.5-159 SITEGRADINGPLAN

~ ".

-,~ 04ES.*PEAKEBAY ~

• ...:::: ::=-1f

300 300 600 FEET

Figure 1 - Location of Cross-sections for Slope Stability Analysis Z:\agriffiths\Calvert Cliffs\Final Calculations\09·4179.0l·F18\Slope Stability updated 9-22-2009\CCNPP Unit 3 - Slope stability\Slope Stability Analysis.docx TRUE COPY- NOT ORIGINAL o I20Q 09-4179.01-F18 ENGINEERS & CONSULTANTS

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 8 of 31 Subject: -- - "'By: Date: _ Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01

Figure 2.5-160 Cross-Sections in PowerblockArea

IDa.. .., 001 _ ... 10 - .. .. m § .. ... ~ w ~ : 1= =:...... 'II • S1:ra.tu'" I-T~,..rc.clI!S.o.nd w .. d " .. a ~ S-b-otuPl llo. - Ch.s0FM'ok. cta.y/SH -XI " II,I,, II" II,,,, ,I :•!I••t IIIM • • !!_ II !J,, I, !!!N ~ oa~w~_~~~*~g~~~_a~~_~~~*_Dg ,! * • ______L ]JstQnc@, f't Dlstonc@, H SECTION A-A SECTION C-C

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i; 311 I ~c:~• S-trcrt\M'l [- r.rro.ce . W .. ~ ch@o 11 s:r:tno - •.-iii 00y7SI; I ~..: lli II IIIIII I! IIII IIII '" IIIII IIIIIIIIII o~~~~m~I~~*~D~~**~w* __ m~rn* • ~ fl M •• ~ ~ ~ • ~ ~ H ~ ~ ~ ~ ~ * • _ D1s-ia.nclil', f'1: Dlstonc@, f~ SECTION B- B SECTION D- D

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! ~~ S~,o~un7,m@Sond I ~.. IIIIIII IIIIIIIIII ~ ...... ------Dls'tclonce, f t SECTION E-E Figure 2 - (2.5-160 Cross-sections in Powerblock Area) Z:\agriffiths\Calvert Cliffs\Final Calculations\09-4179.01-F18\Slope Stability updated 9-22-2009\CCNPP Unit 3 - Slope stability\Slope Stability Analysis.docx TRUE COPY- NOT ORIGINAL o I20Q 09-4179.01-F18 ENGINEERS & CONSULTANTS

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 9 of 31 Subject: -- - "'By: Date: _ Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01

Figure 2.5-161 Cross-Sections in Intake Corridor and Utility Corridor

~~::::~~-==:::~--- ,.

-10• --SIll.. ~++._ IT...... -..- ... "I.- 1""1.. ~J~.'" I

Dh;;"tllnC:l1. rt SECTION F-F

130 O' BENCH.El. eo.o' 110 +' C' BENCH, EL 50.0' 4- 90 70 ~ 0 50 StratUM IIa - Chesapeake +-' 30 d 10 > StratUM lIb - Chesapeake Sand OJ -10 W -30 50 § StrntuM lIe - Chesapeake Clny/Sllt -70 IIIIIIIIIIIIIIIIIIIIIIIIIIIIII -60--40-20 0 20 40 60 80100 140 180 220 260 300 340 380 420 460 500 540 580 620 660 700 740 780 820 Distance} ft SECTION G-G Figure 3 - (2.5-161 Cross-sections in Intake Area and Utility Corridor)

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 10 of 31 Subject: v"'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01

FIGURE2.5-X LOCATIONOFEXCAVATIONCROSS-SECTIONS ~. CliWPWl BAY ~

"" , sJ~

:J:->---J~,,;. ~-~ ~ \'l - C> t to ", '" o~...... --r r:,

w~}1~1 ="

5 CAL E P"---- I 300 0 300 600 FEET ~s

Z:\agriffiths\Calvert Cliffs\Final Calculations\09·4179.0l·F18\SlopeStability updated 9-22-2009\CCNPP Unit 3 - Slope stability\Slope Stability Analysis.docx TRUE COPY - NOT ORIGINAL o ~ 09-4179.01-F18 ENGINEERS & CONSULTANTS

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 11 of 31 Subject: v"'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01

Figure 4 - location of Excavation Cross·sections in CCNPP Unit 3

-1aBENCH

EL.30.O'

FINISHGRADE SECTION A'-A' N.TS.

EL.lI8.O'____

SHORELNE INTAKEBLOPE

BOTTOMEL OF FOREBAY=42.Il' SECTION G'-G' N.T.S.

EL.Il8.O'~

1i:::? aBENQi SHOREUNE INTAKESLOPE EL20.O' tl3.

172., G;]

INTAKENlEA BOTTOMEL. OF UHS·-I!6.S' SECTION G"-G" N.TS. Figure 5 - Excavation Cross-sections in CCNPP Unit 3

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By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 12 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. _0_9_-_41_7_9_.0_1__ ------

Dynamic Analysis

The values for the inertia coefficients kh and kv are provided by Table 1. According to Section 2.5 of CCNPP Unit 3 FSAR, a peak ground acceleration of 0.084g was computed for a magnitude 5.5 earthquake using Random Vibration Theory methods. For conservatism, a peak ground acceleration of 0.15g was adopted for a magnitude 6 earthquake, and 0.075g was chosen for kv (UniStar 2009).

Table 1 - Inertial Effect Coefficients

Area CCNPP Unit 3 0.15 0.075

Material Properties

Tables 2 through 4 present the materials properties from RIZZO calculations, FSAR (UniStar 2009) and the recommended values used in the current analysis for the powerblock, intake area, and utility corridor, respectively. For structural backfill, the best estimate properties were adopted based on "Structural Fill Static Laboratory Testing Results" (Mactec 2009).

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 13 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

Table 2 - Material Properties for Powerblock

Stratum IMaterial propertyl FSAR I RIZZO (1) I Recommended (3) Structural Backfill Unit Weight (pcf) 120 146 145 c (psf) - 0 0 - -- - $ (degrees) - 44 40 c' (psf) 0 0 0 l $' (degrees) 32 42 40 Stratum I: Te rrace Sand Unit Weight (pcf) 120 122 120 c (psf) - 1160 1100 - -- - $ (degrees) - 13 13 c' (psf) 0 620 0 l $' (degrees) 32 26 32 Stratum Ila: Chesapeake Clay/Silt Unit Weight (pcf) 115 116 115 c (psf) - 1400 2500 $ (degrees) - 12 0 c' (psf) 800 960 900 $' (degrees) 26 25 25 - -- - r Su (pst) 2000 2520 - Stratum lib: Chesapeake Sand Unit Weight (pcf) 120 120 120 c (psf) - 2800 2800 $ (degrees) - 17 17 c' (psf) 0 600 0 -- l $' (degrees) 34 32 34 Stratum lie: Chesapeake Clay/Silt Unit Weight (pcf) 110 104 105 2 c (psf) - 30601 ) 5000 $ (degrees) - 15(2) 0 - c' (psf) 2000 2300 -- 2300 - $' (degrees) 27 26 26 I Su (pst) 4000 5920 - (1) Average values reported (Reference e, g, h) (2) Based on one laboratory test (3) Recommended values used in SLOPE/W

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 14 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

Table 3 - Material Properties for Intake Area

Stratum IMaterial propertyl FSAR I RIZZO (1) I Recommended (3) Stratum I: Te rraee Sand Unit Weight (pef) 120 122 120 2 e (psf) - 10001 ) 1100 $ (degrees) - 38(2) 13 t e' (psf) 0 340 --0 $' (degrees) 32 28 32 Stratum Ila: Chesapeake Clay/Silt Unit Weight (pef) 120 117 115 - e (psf) - 5360 3400 $ (degrees) - 6 0 e' (psf) 800 1420 1400 - -- - $' (degrees) 28 28 28 l Su (pst) 4400 3480 - Stratum lib: Upper Chesapeake Sand Unit Weight (pef) 115 121 120 e (psf) - NA 2800 $ (degrees) - NA 17 - - -- - [ e' (psf) 0 720 0 $' (degrees) 34 27 34 Stratum lib: Lower Chesapeake Sand Unit Weight (pef) 120 121 120 - e (psf) - NA 2800 - $ (degrees) - - NA -- 17 - [ e' (psf) 0 220 0 $' (degrees) 34 32 34 Stratum lie: Chesapeake Clay/Silt Unit Weight (pef) 110 108 110 - - e (psf) - 2170 4800 $ (degrees) - 12 0 - e' (psf) 1200 1000 -- 1000 - $' (degrees) f 30 31 30 Su (pst) 5000 4820 - (1) Average values reported (Reference e, g, h) (2) Based on one laboratory test NA - None Available (3) Recommended values used in SLOPE/W

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By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 15 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

Table 4 - Material Properties for Utility Corridor

Stratum IMaterial propertyl FSAR I RIZZO (1) I Recommended (3) Stratum I: Te rraee Sand Unit Weight (pef) 120 122 120 e (psf) - 1160 1100 - -- - $ (degrees) - 13 13 e' (psf) 0 620 0 l $' (degrees) 32 26 32 Stratum Ila: Chesapeake Clay/Silt Unit Weight (pef) 120 116 115 e (psf) - 1400 2500 - - - $ (degrees) - 12 0 e' (psf) - 960 900 $' (degrees) - 25 25 - -- - l Su (pst) 2000 2520 - Stratum lib: Chesapeake Sand Unit Weight (pef) 120 120 120 - -- e (psf) - 2800 2800 $ (degrees) - 17 17 e' (psf) 0 600 0 -- l $' (degrees) 34 32 34 Stratum lie: Chesapeake Clay/Silt Unit Weight (pef) 110 104 105 2 30601 ) - e (psf) - - 5000 - - $ (degrees) - 15(2) -- 0 - e' (psf) - 2300 2300 $' (degrees) - 26 26 I Su (pst) 4000 5920 - (1) Average values reported (Reference e, g, h) (2) Based on one laboratory test (3) Recommended values used in SLOPE/W

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 16 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. _0_9_-_41_7_9_.0_1__ ------

Analysis of Cross-Sections

Figures of critical slip surfaces illustrated below show FOSs based on the Morgenstern-Price method (Morgenstern 1965).

Section A

Termination Elevation of Structural Fill = 33.7 ft, using boring B-313 (Reference f) Two cases are considered: a) Groundwater Elevation = 33.7 ft (at the boundary of Structural Fill and Chesapeake sand) b) Groundwater Elevation = 55 ft (within the Structural Fill)

Case a Table 5 - Computed FOS for Section A- Case a

Static Analysis Pseudo-static Analysis I Method ESA TSA ESA I Ordinary 1.92 1.73 1.32 Bishop 2.19 1.76 1.47 Morgenstern-Price 2.18 1.76 1.47

Figures 6 through 8 show the slip surfaces for Section A- Case a for both static and pseudo-static analyses. The reports outputted by SLOPE/W for both analyses are attached in the Appendix. Units in the figures are in feet.

100 90 FOS Static =.---2.18 80 'j------...... _--" c:: 70 Unit lA/eight: 145 o 80 Cohesion: 0 +:i 50 Structural Backfill ('IJ Phi: 40 > 40 Ql 30 t=:-;:~;::+;.7;r;_------~ [jJ 20 Unit Weight: 120 10 Cohesion: 0 Stratum lib - Chesapeake Sand o Phi: 34 -10 L..-...... L.._...l...----l._....L...---l_....I..._l...-...... L.._...l...----L_....L...---l_.....L..._l...-...... L.._...l...----L_....L...---l_.....L..._l...-...... L.._...l...----L_....l----IJ o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 Distance

Figure 6 - Critical Slip Surface for Section A- Case a - Static - ESA

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 17 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 --- FOS Pseudo-static (TSA) =-1.76

100 90 80 '1-;-;::~=:;:::-;:;:-- -.....__..... 70 Unit VI/eight: 145 5 60 Cohesion: 0 ii 50 Phi: 40 Structural Backfi II iii 40 iIi 30r=--;-:==;:::-:~------=::::::::::"",. ~ 20 Unit Weight: 120 10 Cohesion: 2800 Stratum lib - Chesapeake Sand o Phi: 17 -10 L..----L_--'-_.L-----l_--'-_...l...-_L..----L_--'-_.L-----l_...J...._..J...-_'-----'-_....l...._.L-----l_...J...._...l...-_'-----'-_....l...._.L..-----L_...JJ o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 Distance

Figure 7 - Critical Slip Surface for Section A- Case a - Pseudo-static - TSA

100 90 FOS Pseudo-static {ESA} =.--1.47 80 '1~~~:--:-::------...... _ _' 70 Uni t Vv'ei ght: 145 5 60 Cohesion: 0 Structural Backfill ii 50 Phi: 40 iii 40 t-:--;-;::;-~;:;:~i'?'O------_-_-----.:~ iIi 30 r Unit \J\leight: 120 20 Cohesion: 0 10 Stratum lib - Chesapeake Sand o Phi: 34 -10 L...-----L_--'-_-'------l_--'-_...l...-_L..----L_--'-_-'------l_...J...._..J...-_'-----'-_....l...._.L..-----L_...J...._..J...----J'----'-_...J.-_.l...----L_...JJ o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 Distance

Figure 8 - Critical Slip Surface for Section A- Case a - Pseudo-static - ESA

Caseb

Table 6 - Computed FOS for Section A- Case b

Static Analysis Pseudo-static Analysis I Method ESA TSA ESA I Ordinary 1.63 1.61 1.14 Bishop 1.89 1.68 1.27 Morgenstern-Price 1.89 1.68 1.28

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 18 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ---

Figures 9 through 11 show the slip surfaces for Section A- Case b for both static and pseudo-static analyses. The reports outputted by SLOPE/W for both analyses are attached in the Appendix. Units in the figures are in feet. FOS Static =.---1.89

100 90 80'l~==-:::::------..._-""",","-- 70 Unit I/v'eight: 140 c o 60 Cohesi on: 0 :0:; 50 --Ph~-40------;sLFucfuF~-Era-CKfirr------ro 40 >(\) 30 ~=:_:;::;_:;=_:;~------.::::!J..I W 20 Unit Weight: 120 10 Cohesi on: 0 Stratum lib - Chesapeake Sand o Phi: 34 -10 L..-.....J.._....L..._J....----L_....J..._..l..---l_...... L._...J...._.L..---L_....L..._J....----L_....J..._...J...._L..-.....J.._...J...._.L..---L_....l..._..l..---l_....J...---lJ o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 Distance

Figure 9 - Critical Slip Surface for Section A- Case b - Static - ESA FOS Pseudo-static (TSA) =.---1.68

100 90 80 '1=:-:;=:-:-:::------_ 70 Unit Weight: 145 60 Cohesi on: 0 50 -Ph~40------Sfrucfurar8aCKfi~------40 30 ~UU~nititVWV;e~igrlh;tt:~1l4455------....=:::::~~jj:lJ:Ji::l::l=:.------H 20 Cohesion: 2800 10 Stratum lib - Chesapeake Sand o Phi:17 -10 L..-.....J.._....L..._J....----L_....l..._...l..---l'--...... L._...J...._.L..---L_....l..._J....----L_....J..._...J....--l'--...... L._...J...._.L..---L_....l..._..l..----L_....J...---lI o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 Distance

Figure 10 - Critical Slip Surface for Section A- Case b - Pseudo-static - TSA

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 19 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

FOS Pseudo-static (ESA) = 1.28 ~

100 90 80 t-=-:-:;-:-::-:-:::;------...... ""----~ ..... 70 Unit \tVeight: 145 60 Cohesion: 0 50 -Ph~40------SfrDcfurarBacRfi~------40 30 F-:-:-~~:-:-:-:::----~------~-----.::::!:.ll 20 Unit Weight: 120 10 Cohesion: 0 Stratum lib - Chesapeake Sand o Phi: 34 -10 L..----I.._...l...-----JL....---l..._..l..-----I._.....L..._.l...----I.._...l...-_L....----I.._..l..-----I_.....L..._..l..----l._....L..._.l...----I.._....I...-----J_--L.._..l..-----I._....IJ o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 500 520 Distance

Figure 11- Critical Slip Surface for Section A- Case b - Pseudo-static - ESA

Section B

Termination Elevation of Structural Fill = 38.3 ft, using boring B-419 (Reference f) Two cases are considered: a) Groundwater Elevation = 38.3 ft (at the boundary of Structural Fill and Chesapeake sand) b) Groundwater Elevation = 55 ft (within the Structural Fill)

Case a

Table 7 - Computed FOS for Section B- Case a - Static Analysis Pseudo-static Analysis Method ESA TSA ESA Ordinary 1.95 1.76 1.35 Bishop 2.22 1.81 1.49 Morgenstern-Price 2.22 1.81 1.49

Figures 12 through 14 show the slip surfaces for Section B- Case a for both static and pseudo-static analyses. The reports outputted by SLOPE/W for both analyses are attached in the Appendix. Units in the figures are in feet.

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 20 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ---

100 90 80~==::-;:;------...... __...... FOS Static =2.22 l:: 70 Unit Weight: 145 .-- o 60 Cohesion: 0 :.;:::; Structural Backfilll ro 50 Phi: 40 > <1l 40 F-:-----:-~------~------::!llI:IIH~IIHftrIT'llP'----""""i4 LU 30 Unit Weight: 120 20 Cohesi on: 0 Stratum lib - Chesapeake Sand 10 Phi: 34 OL..----l_---L_-'-_....L..._...L..._.L..----l_...... I._-'-_....L..._...L..._.L..----l_.....J.._-'-_....L..._...L..._.L..----l_...... I._-'-_....L..._..l..J.----l o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 Distance

Figure 12 - Critical Slip Surface for Section B- Case a - Static - ESA FOS Pseudo-static (TSA) .--= 1.81

100 90 8°'tlJ;ili\~~m------...... _--" c 70 Unit \Neight: 145 o 60 Cohesi on: 0 Structural Backfi II ~ 50 Phi: 40 40 F7":'""":-:-;-;-;-;--;-:--:;-:::;:;;------:.::::..------41 w 30 Unit Weight: 120 20 Cohesion: 2800 Stratum lib - Chesapeake Sand 10 Phi:17 OL..----l_.....J.._-'-_....L..._"'--_.L..----l_---'-_-'-_....L..._"'--_L..----L_.....J.._...... _-'-_"'--_L...----L_---'-_...... _-'-_.l-L---l o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 Distance

Figure 13 - Critical Slip Surface for Section B- Case a - Pseudo-static - TSA

100 90 80Jt------~ ---~ FOS Pseudo-static (ESA) .1.49 l:: 70 Unit Weight: 145 o 60 Cohesion: 0 Structural Backfi II ro 50 Phi: 40 -> <1l 40 F--;-;:7':"';";:;:;-::;:::-:;-::;;;------~!QIIJIIJtl,_-----.f4 LU 30 Unit Weight: 120 20 Cohesion: 0 Stratum lib - Chesapeake Sand 10 Phi: 34 OL..----l_...... I._-'-_....L..._"'--_.L...----l_---L_-'-_...... _-'-_.l..----lL...----L_---'-_...... _-'-_"'--_L...----l_---'-_-'-_....L.JL-..J o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 Distance

Figure 14 - Critical Slip Surface for Section B- Case a - Pseudo-static - ESA

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 21 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ---

Caseb Table 8 - Computed FOS for Section B- Case b - Static Analysis Pseudo-static Analysis Method ESA TSA ESA Ordinary 1.85 1.74 1.23 Bishop 2.12 1.78 1.40 Morgenstern-Price 2.12 1.79 1.41

Figures 15 through 17 show the slip surfaces for Section B- Case b for both static and pseudo-static analyses. The reports outputted by SLOPE/W for both analyses are attached in the Appendix. Units in the figures are in feet. FOS Static -= 2.12

100 90 80,....~-~------~ ~ c: 70 Unit \to/eight: 145 -----~ o 60 --~oJ~~i~~~~------~fHG~a~~~H~------_ -ro 50 Phi: 40 >(1) 40 F""7'7~:7':"'":-:-':"""":'"-:::-::------""'::::.I.J UJ 30 Unit Weight: 120 20 Cohesion: 0 Stratum lib - Chesapeake Sand 10 Phi: 34 oL...----JL...----L_...... L._....l..._...J...._..L...-_L...----l._...... L._....l.._...J...._...L..._l..----J_...... L_....l.._....L.._...L..._.l...----J_---L_.....J.._....l..IL-..J o 20 40 60 80 100120140160180200220240260280 300 320 340 360 380 400 420 440 460 480 Distance Figure 15 - Critical Slip Surface for Section B- Case b - Static -ESA FOS Pseudo-static (TSA) .-= 1.79

100 90 80r~==::_::~------.....__...... oc 70 Unit Weight: 145 60 __ S:~I::.~~~n~.£l ~-l:lGH:J~BacMi ilj "- ~ 50 Phi: 45 ~ (J) 40 r""i"i:::T+"'C;;;;:::::r:-;::-:;-:;:;;------..::..:...... -....:::::==------1lIl W 30 Unit Weight: 120 20 Cohesion: 2800 Stratum lib - Chesapeake Sand 10 Phi: 17 OL..----l_...... L_....l.._...J...._...L..._l..----l._...... L_....l.._...J...._...L..._l..----l._...... L._....l.._...J...._...L..._l..----l._...... L._....l.._...J...._..l..L---l o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 Distance

Figure 16 - Critical Slip Surface for Section B- Case b - Pseudo-static - TSA

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 22 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------FOS Pseudo-static (ESA) .--=1.41

100 90 80't------~------__ l:: 70 Unit Weight: 145 ...... ---- o 60 __~~~~~~~~~ ~~~~~~~~~ _ ro -> 50 Phi: 40

O'-----"-...... --'--"-----"-...... --'--"-----"-...... - ...... -"-----"----'--...... -"-----'----'--...... -"-----'----'--...... L-...J o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 420 440 460 480 Distance

Figure 17 - Critical Slip Surface for Section B- Case b - Pseudo-static - ESA

Section C

Termination Elevation of Stratum I- Terrace Sand = 60.8 ft, based on borings B-324 and B-765 (Reference f) Groundwater table = 80 ft (UniStar 2009)

Table 9 - Computed FOS for Section C

- Static Analysis Pseudo-static Analysis Method ESA TSA ESA Ordinary 1.96 3.15 1.31 Bishop 2.02 3.24 1.36 Morgenstern-Price 2.02 3.24 1.36

Figures 18 through 20 show the slip surfaces for Section C for both static and pseudo-static analyses. The reports outputted by SLOPE/W for both analyses are attached in the Appendix. Units in the figures are in feet.

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 23 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 --- FOS Static =-2.02 120

110 -

100 - l:: ~ o 90 _Unit Weight: 120 :0:; ~~3~~e?~~~~~ ~_~_W~_~_b -_-_~ m 80 __ __-_-_-_-__-_-_-__-_-_-_-__-_-_-_-__-_-_-__-_-_-_-__-_-_-_-__-_-_-__-_-_-_-__-_-_-__-_-_-__-_-_-_-__-_-_-_-__ > Q) Phi: 32 Stratum 1- Terrace Sand [jJ 70 -

60 Unit Weight: 115 Cohesion: 900 50 -Phi: 25 Stratum Iia - Chesapeake Clay/Silt 40 '--_.L....1_..1_.....l1__1"--_.....1_.....1_...I_...... II__'--I_.L....I_...I_.....lI_...... II__.....I_...I_.....I.I_.....lI.....L-----l1 o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance Figure 18 - Critical Slip Surface for Section C- Static - ESA

FOS Pseudo-static (TSA) = 3.24

120 - 110

100 l:: 0 90 Unit Weight: 120 :0:; m 80 -~~~~~~~~llJJ------~J~~·~~I·W~!~~j~~~~~~--~-=-=--;-=-=-=--~-=-=--~-=-=--=-~-=-=--=-=-=--=-~-=-=--=-=-=-=--~-=-=--=-=-=-=--~-=-~--~-=-=-=--~-=-~--~ >Q) Phi: 13 --"'-'-'-L.L.L-L"""'-' - errace Sand [jJ 70 60 Unit Weight: 115 Cohesion: 2500 50 Phi: 0 Stratum Iia - Chesapeake Clay/Silt 40 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance Figure 19 - Critical Slip Surface for Section C- Pseudo-static - TSA FOS Pseudo-static (ESA) =-1.36 120 -

110 -

100 - l:: ~ o 90 _ Unit Weight: 120 :0:; ~~3~~e?~~~~~ ~~_~_~ ~_~_~_- -.-_~ m 80 ______-_-_-_-__-_-_-__-_-_-__-_-_-_-__-_-_-__-_-_-_-__-_-_-__-.-_-__-_-_-_-__-_-_-__-_-.-__-_-_-_-__-_-_-_-__ > Q) Phi: 32 Stratum 1- Terrace Sand [jJ 70 - 60 I------l Unit Weight: 115 Cohesion: 900 50 - Phi}5 I Stratum lIa - Chesapeake Clay/Silt IIIIIIIIIIIIIII I 40 o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance Figure 20 - Critical Slip Surface for Section C- Pseudo-static - ESA

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 24 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

Section D

Termination Elevation of Stratum I- Terrace Sand = 75.1 ft, based on borings B-329 and B-744 (Reference f) Groundwater table = 80 ft (UniStar 2009)

Table 10 - Computed FOS for Section D - Static Analysis Pseudo-static Analysis Method ESA TSA ESA

Ordinary 1.93 4.09 1.32 Bishop 1.97 4.14 1.38 Morgenstern-Price 1.97 4.14 1.38

Figures 21 through 23 show the slip surfaces for Section D for both static and pseudo-static analyses. The reports outputted by SLOPE/W for both analyses are attached in the Appendix. Units in the figures are in feet. FOS Static -= 1.97 120 C 110 f- a 100 N'=O""-'-...,...... ,..,..,.....,....,...... ,....,,....,...... ,,...... ,....-...,...... ,...... ,..---..~ ~>- 90 f- Unit Weight: 120 Cohesion: 0 ~ ~ k1P~hi~:L._~_~~..L.i.t_~~~_-;_i3~2~~u5uh';;;;;;-?"9ciO--=~~"~'~::'=~~~~~g...L~_t:-_(_l-...I~_- _C_OI_1~L.S_i 9.L.10_0_...LI_S_tr...l~_tu_m_IIl...la_-_c_.L.~"e_-~_~_~..l.f-_a~_-e_-~...l,-_I~_~-_/~_~L...il;,_-c.'~~n'~,"~~~~;;~~~:======j1-_-_-_--..l.I-_-_--_-...L~_--_-_-...I-IL...--_-_-_-~.L..-_-_--_-..L.I-_--_-_-...L~-_-_-_-...I- ::L o_n_: -_-_-.L.- o 20 40 60 80 140120100 160 180 280260240220200 320300 360340 380 400 Distance

Figure 21 - Critical Slip Surface for Section D- Static - ESA

FOS Pseudo-static (TSA) .4,14

120 Unit Weight: 120 110 Cohesion: 1100 § 100 F'-P_h_i:_1_3-+ ...... TTT ~ 90 F==:=7:':::?'1'~'3":~"i""""~~~~ -

Figure 22 - Critical Slip Surface for Section D- Pseudo-static - TSA

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 25 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

FOS Pseudo-static (ESA) = 1.38

120 -- c 110 o 100 90 F'-:-U""n"'"'it-:-W""'e-:-jg"";"h-:-t:-:1""'2"""0--"""C""'ol;-le-s""'io-n-::O"...... --~ - Phi: 32 "'ll.lIIIlnn" 80 ~Unlt\¥eigh1:115 Cotlesion: 2500 70 -Phi: e Str~tum III a - c~esaPTake l,ay/siIt 60 L..-_..I...-_-'--_IIIII...... _ ...... _-'-_---'-_---l._---'__'--_.L...-_..I...-_-'--_-'-_IIIIIII...... _-'-_---'-_---l._---'__'------' o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 400 Distance Figure 23 - Critical Slip Surface for Section D- Pseudo-static - ESA

Section E

Groundwater table = 80 ft (UniStar 2009)

Table 11 - Computed FOS for Section E

- Static Analysis Pseudo-static Analysis Method ESA TSA ESA Ordinary 1.98 3.15 1.34 Bishop 2.05 3.15 1.41 Morgenstern-Price 2.05 3.15 1.41

Figures 24 through 26 show the slip surfaces for Section E for both static and pseudo-static analyses. The reports outputted by SLOPE/W for both analyses are attached in the Appendix. Units in the figures are in feet. FOS Static =--2.05

110 c: 100 0 90 Unit Weight: 120 ..('IJ Cohesion: 0 ij) 80 ------Phi: 32 Stratum 1- Terrace Sand iIi 70

60 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 380 Distance

Figure 24 - Critical Slip Surface for Section E- Static - ESA

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 26 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------FOS Pseudo-static (TSA) =-3.15

110

100 al:: ~ 90 Unit \lv'eight: 120 (ll Cohesion: 1100 ~ 30 ------~·~+·+~~-~+·~~·~+·I~I~+~~+~_b~------Phi: 13 iIi 70

60 0 20 40 60 30 100 120 140 160 180 200 220 240 260 230 300 320 340 360 330 Distance Figure 25 - Critical Slip Surface for Section E- Pseudo-static - TSA FOS Pseudo-static (ESA) =.---1.41

110

l:: 100 a Unit Weight: 120 (ij 90 Cohesion: 0 >Q) 80 Phi:------32 Terrace Sand iii 70

60 0 20 40 60 80 100 120 140 160 180 200 220 240 260 230 300 320 340 360 380 Distance Figure 26 - Critical Slip Surface for Section E- Pseudo-static - ESA

Section F

Termination Elevation of Stratum I-Terrace Sand = 70 ft Termination Elevation of Stratum lIa-Chesapeake Clay/Silt = 45 ft Termination Elevation of Stratum lib-Chesapeake Sand = -20 ft Elevations were based on borings located along the Utility Corridor, (Reference f)

Groundwater Level = 24 ft (UniStar 2009)

Table 12 - Computed FOS for Section F

- Static Analysis Pseudo-static Analysis Method ESA TSA ESA Ordinary 2.20 2.73 1.57 Bishop 2.34 2.81 1.68 Morgenstern-Price 2.34 2.82 1.69

Figures 27 through 29 show the slip surfaces for Section F for both static and pseudo-static analyses. The reports outputted by SLOPE/W for both analyses are attached in the Appendix. Units in the figures are in feet.

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 27 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

100 90 Unit Weight: 115 80 Cohesion: 900 FOS Static .2.34 70 f---t------.....;;;:lIIIoI""'--- Phi: 25 60 Stratum Iia - Chesapeake Clay/Silt c 50 o :;:::::; 40 ro > 30 (1) 20 W Unit Weight: 120 10 Cohesion:O Stratum lib - Chesapeake Sand o Phi: 34 -10 f---t~~~o:__~___=~~---=~------___4 -20 Unit Weight: 105 Cohesion: 2300 -30 Phi· 26 Stratum lie - Chesapeake Clay/Silt -40 L..6_...... _...L..._-'-_...... _.....L._---'__l...._...... _...L..._-'-_...... _.....L._---'__l...._...... _...L..._...... 1------l o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance Figure 27 - Critical Slip Surface for Section F- Static - ESA

FOS Pseudo-static (TSA) ~

100 90 80 70 60 c 50 o 40 :;:::::; ro > 30 (1) 20 ------_.~~-~~ W Unit Weight: 120 10 Cohesion: 2800 o Phi: 17 -10 H~~~-:-:-~,.....~~-='::""""------i -20 Unit Weight: 105 Cohesion: 5000 -30 Ph': 0 -40 '--'_...... _ ....._.....1__...... _ ...... _.....1.__...... _ ...... _.....1.__'--_...... _ ....._.....1__...... _ ...... _.....1.__...... _-' o 20 40 60 80 100 140120 180160 200 220 240 260 280 300 320 340 360 Distance Figure 28 - Critical Slip Surface for Section F- Pseudo-static - TSA

Z:\agriffiths\Calvert Cliffs\Final Calculations\09-4179,01-F18\Slope Stability updated 9-22-2009\CCNPP Unit 3 - Slope stability\Slope Stability Analysis.docx TRUE COPY - NOT ORIGINAL o 09-4179.01-F18 ENGINEERS & CONSULTANTS

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 28 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. _0_9_-_41_7_9_.0_1__ ------

100 Unit Weight: 120 90 Cohesi on: 0 ..---~Phi: 32 Unit Weight: 115 80 atum I_Terrace Cohesion: 900 FOS Pseudo-static (ESAl.1.69 70 H------.;;;;;:a"""':.!iPhi: 25 60 Stratum lIa - Chesapeake Clay/Silt c 50 o :p 40 ro > 30 Q) 20 W 10 Unit Weight: 120 Stratum lib - Chesapeake Sand Cohesion: 0 o Phi: 34 -10 -20 H-~~:-:-:-:--:~---:C~o':"'"he-s':"'"io-n:-::2:':':'30::-:0:------1 -30 -40 L....I._..L...._...L..._...I-_.....L._.....l._.....l__....._..L...._...L..._...I-_.....L._.....l._.....l__....._ ....._...L..._....L..l----.J o 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300 320 340 360 Distance Figure 29 - Critical Slip Surface for Section F- Pseudo-static - ESA

Section G

Termination Elevation of Stratum I-Terrace Sand = 63 ft, using borings B-778 and B-779 (Reference f) Termination Elevation of Stratum lIa-Chesapeake Clay/Silt = 31.7 ft, using borings B-778 and B-779 (Reference f) Termination Elevation of Stratum lib-Chesapeake Sand = -18.7 ft, using borings B-771 and B-773 (Reference f) Groundwater Level (Intake Slope) = 36.6 (UniStar 2009) Groundwater Level (Intake Area) = 10 ft (UniStar 2009)

Table 13 - Computed FOS for Section G

- Static Analysis Pseudo-static Analysis Method ESA TSA ESA Ordinary 1.87 1.86 1.24 Bishop 2.04 1.92 1.34 Morgenstern-Price 2.05 1.93 1.35

Figures 30 through 32 show the slip surfaces for Section G for both static and pseudo-static analyses. The reports outputted by SLOPE/W for both analyses are attached in the Appendix. Units in the figures are in feet.

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 29 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 --- FOS Static -= 2.05

130 110 90 C 70 ~ 50 ~ 30 f---f""'u;';;;n""it;';;;w=ei;';;;g"'ht;';;;:""'12;';;;0=;';;;C"'o;';;;he"'s;';;;io""n;';;;:0=====1:::-1 III 10 iIi -10 Phi: 34 r=1--:~~-.~---=-~---.~------=::::::::::====~:::::::::""_------I -30 Unit Weight: 110 Cohesion: 1000 -50 Phi: 30 Stratum lie - Chesapeake Clay/Si It -70 L...LJ----l----L----L---L.---L..---L.....J...... L...... L...... L-....L-...l..-...l..-.l...-.L..-l...... J----l----L----L---l.---L.---L.....J...... J...... L...... L...... L-...l..-...l..-..L...-.l...-.L..-l...... J'---l----L---l.---L.---L....J...... J...... L...... L...... J.L....J -60-40-20 0 20406080100 140 180 220 260 300 340 380 420 460 500 540 580 620 660 700 740 780 820 860 Distance

Figure 30 - Critical Slip Surface for Section G- Static - ESA FOS Pseudo-static (TSA) -= 1.93

Unit Weight: 120 130 Cohesion: 1100 110 Phi: 13 90 C 70 ~ 50 ~ 30 f---f""'U;';;;n""it==W=ei;';;;g=ht;';;;:""12;';;;0=;';;;Co':':';';;;,e=s==io""n:==2=8=':0;';;;0=q III 10 Phi: 17 Stra iIi -10 I=l---~--~------=::::::=::=::!:!:::::!:~=------~ -30 Unit Weight: 110 -50 Phi: 0 Stratum lie - Chesapeake Clay/Silt -70 L...LJ---'---I.---I.---L...... L...... L...... L...... L...... L...-.l...-.l...-L..-l...... J---'---I.---L---L...... L...... L...... L...... L...... L...-..L...-.l...-L..-l...... J---I.---I.---L---L...... L...... L.....u.--J -60-40-20 0 20 4060 80100 140180220260 300 340 380 420 460 500 540 580 620 660 700 740 780 820 860 Distance

Figure 31 - Critical Slip Surface for Section G- TSA

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 30 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------FOS Pseudo-static (ESA) =.------1.35

Uni t vVei ght: 115 130 Unit \l\leight: 120 Cohesion: 1400 110 28:..-_~~ Cohesion: 0 Phi: 90 Phi: 32 c: 70 o ~ 50 ~~~~u_r12~I~.: _~~':.s..':P_e1l.!<~_~I _ ro 30 I--F=::'==::'==::'======::'='::=::'='::~l > Unit Weight: 120 Cohesion: 0 (1) 10 Phi: 34 W -10 I=I------..::::::::::::=::!;;;;;~~::::::::....------__l -30 Unit Weight: 110 -50 Phi: 30 Stratum lie - Chesapeake Clay/Silt -70 LJJ'---L---l...... L.....J...... J...... L...... J...... L..-.L..-L...... J---l.---L...... L.....J...... J...... L...... J...... L..-.L..-L...... J---l.---L.....J...... J...... J...... L.....J...... L..-.L..-L...... J.---l.---L.....J...... J...... L...... L.....J...... L..-.L...... JL...... J.---l.LJ -60 -40 -20 0 20 40 60 80 100 140 180 260220 300 340 380 420 460 500 540 580 620 660 700 740 780 820 860 Distance

Figure 32 - Critical Slip Surface for Section G- Pseudo-static - ESA

5 RESULTS Tables 4.1 and 4.2 summarize the factors of safety for each cross-section for both the static and pseudo static analyses.

Table 14 - Summary of Factors of Safety - Static Analysis

Effective Stress Analysis Slope Section Ordinary Bishop Morgenstern-Price A- Case a 1.92 2.19 2.18 A- Case b 1.63 1.89 1.89 B- Case a 1.95 2.22 2.22 B- Case b 1.85 2.12 2.12 C 1.96 2.02 2.02 D 1.93 1.97 1.97 E 1.98 2.05 2.05 F 2.20 2.34 2.34 G 1.87 2.04 2.05

By: ATG Date: 4/7/2010 Slope Stability Analysis Sheet No. 31 of 31 Subject: V'By: Date: Calvert Cliffs NPP Unit 3 Project. No. 09-4179.01 ------

Table 15 - Summary of Factors of Safety - Pseudo-static Analysis

~ Slope Total Stress Analysis Effective Stress Analysis I Section Ordinary Bishop Morgenstern-Price Ordinary Bishop Morgenstern-Price A- Case a 1.73 1.76 1.76 1.32 1.47 1.47 A- Case b 1.61 1.68 1.68 1.14 1.27 1.28 B- Case a 1.76 1.81 1.81 1.35 1.49 1.49 B- Case b 1.74 1.78 1.79 1.23 1.40 1.41 C 3.15 3.24 3.24 1.31 1.36 1.36 D 4.09 4.14 4.14 1.32 1.38 1.38 E 3.15 3.15 3.15 1.34 1.41 1.41 F 2.73 2.81 2.82 1.57 1.68 1.69 G 1.86 1.92 1.93 1.24 1.34 1.35

6 CONCLUSION

The Ordinary method errs on the conservative side and yields lower FOSs because only moment equilibrium is satisfied. The Bishop's method considers moment equilibrium and the normal interslice force. The Morgenstern-Price method considers moment and force equilibrium, and the interslice normal and shear forces.

According to Duncan (1996), typical minimum acceptable values of FOS are about 1.5 for normal long-term loading conditions, and 1.0 to 1.2 for an infrequent loading condition, such as earthquakes. The calculated FOSs for all slopes exceed the minimum acceptable values as shown in Tables 14 and 15. Therefore, the slopes in the powerblock, utility corridor and intake area have sufficient static and dynamic stability against slope failure.

For pseudo-static cases, the total stress conditions are more representative for dynamic conditions since porewater pressures do not have time to dissipate.

Z:\agriffiths\Calvert Cliffs\Final Calculations\09-4179.01-F18\Slope Stability updated 9-22-2009\CCNPP Unit 3 - Slope stability\Slope Stability Analysis.docx