2025-01648 Accepting SAFCA’s Urban Level of Flood Protection Reports (LR25-006) Part 3 — Sacramento City Council, October 21, 2025 (part 2 of 4)

Appendix C Seepage and Stability Analysis Results
Summary
Table C-1. Seepage and Stability Analysis Results Summary Table C-1. Seepage and Stability Analysis Results Summary Bot. of
Blanket
Total
Head (ft) Gradient3
Allowable
Gradient
Bot. of
Blanket
Total
Head (ft) Gradient3
Allowable
Gradient Considerations for Through Seepage
Breakout
200-year
WSE
Breakout
HTOL
WSE
Meets TS
Criteria?
200-year
WSE
HTOL
WSE
22 ft Total
Flood
Drawdown
(TFD)
8 ft Rapid
Drawdown
(RD)
7 200-yr HTOL 200-yr HTOL
1 1080+75
EFSM
(GEI/HDR, 2016)
Existing Conditions
200-foot wide High Ground Supported by I5 Boat Structures 197 0 32.20 -2.00 31.22 <0.01 0.50 33.67 0.04 0.60
•Through seepage terminates at I-5 retaining
wall
•Assumed Caltrans operates system of
pumps to control water uplift pressures at
base of roadway slab monolith.

N/A N/A Meets N/A N/A 1.10

1.20 (1.10)

34.84 37.84 32.24 35.24
2 1088+50
Reach D Berm DDR
(GEI/HDR, 2019a)
Drained stability berm Berm Toe (Layers 3-4) 80 28 21.14 -2.00 32.70 0.50 0.53 34.40 0.57 0.63 •Flow captured by drained stability berm 0.6 0.6 Meets 2.08 2.00 1.00

1.20 (1.08)

35.56 37.56 32.17 35.17
Landside Toe (Layer 2) 47 0 30.38 17.50 31.32 0.07 0.50 32.75 0.18 0.60 Landside Toe (Layers 2-4) 47 0 30.38 0.00 32.30 0.06 0.50 34.91 0.15 0.60 Landside Depression 1 (Layer 3) 92 33 17.26 11.33 18.55 0.22 0.56 18.80 0.26 0.67 Landside Depression 1 (Layer 3-4) 92 33 17.26 3.99 18.59 0.10 0.56 18.84 0.12 0.67 Landside Depression 2 (Layer 3) 137 78 17.61 10.50 20.18 0.36 0.66 20.60 0.42 0.76 Landside Depression 2 (Layer 3-4) 137 78 17.61 2.97 20.27 0.18 0.66 20.70 0.21 0.76 Landside Depression 3 (Layer 3) 240 181 17.44 10.50 22.69 0.76 0.80 23.26 0.84 0.90 Landside Depression 3 (Layer 3-4) 240 181 17.44 2.13 22.73 0.35 0.80 23.29 0.38 0.90 1100+00
(Reach 4-2)
EFSM
(GEI/HDR, 2016)
Drained berm and
thickened fill
Landside at Toe Drain (Layers 2-3) 86 16 25.65 11.93 32.51 0.50 0.53 34.20 0.62 0.63 •Flow Captured by drained berm/toe drain 0.0 0.0 Meets 1.96 1.85 1.09 1.26 35.45 37.45 32.04 35.02 1101+75
(Reach 4-2)
EFSM
(GEI/HDR, 2016)
Drained stability berm Berm Toe (Layers 3 and 7) 81 7 23.40 7.33 29.69 0.39 0.51 31.01 0.47 0.61 •Flow captured by drained berm/toe drain 0.0 0.0 Meets 2.32 2.19 1.13 1.50 35.43 37.43 32.01 34.99 Landside Toe (Layers 1-2) 62 0 30.88 7.00 31.51 0.03 0.50 33.58 0.11 0.60 Landside Toe (Layers 1-3) 62 0 30.88 -7.00 31.70 0.02 0.50 34.21 0.09 0.60 Landside Depression (Layer 2) 248 186 20.79 7.00 27.77 0.51 0.80 29.43 0.63 0.90 Landside Depression (Layers 2-3) 248 186 20.79 -7.00 29.97 0.33 0.80 32.19 0.41 0.90 Landside Toe (Layer 2) 57 29 21.31 7.34 27.09 0.41 0.56 28.20 0.49 0.66 Landside Toe (Layers 2-3) 57 29 21.31 -9.00 29.41 0.27 0.56 30.96 0.32 0.66 Landside Depression (Layer 2) 174 146 18.71 8.16 26.04 0.69 0.79 27.30 0.81 0.89 Landside Depression (Layers 2-3) 174 146 18.71 -5.14 28.49 0.41 0.79 29.93 0.47 0.89 Landside Toe (Layer 2) 51 96 22.47 0.00 30.71 0.37 0.69 33.05 0.47 0.79 Landside Depression 1 (Layer 2) 65 110 21.62 0.00 30.59 0.41 0.72 32.92 0.52 0.82 Landside Depression 2 (Layer 2) 230 275 18.88 0.00 29.35 0.55 0.80 31.50 0.67 0.90 2024 ULDC WSEs
(ft)

32.10 35.09
3 0.8 1.9 Meets
N/A
1108+00
(Reaches
5-2 and 6-1)
Cutoff Wall to
El. -15
•Flow cut off by shallow cutoff wall 0.0 0.0 Meets
1092+10 Existing Conditions 2.43 2.13 1.19
•Flow through SM material
•Low head differential
•No known past performance issues related
to through seepage

1.30 4

35.23 37.23
Cutoff Wall to
El. 0
•Flow cut off by shallow cutoff wall 0.0 0.0 Meets 1.43 1.43 EFSM
(GEI/HDR, 2016)
1116+97
(Reaches
6-2 and 7-1)
Gradient Calculation Location X (ft)¹ D (ft)²
Analysis
WSEs (ft)

1.20 37.73 34.73
N/A
•Flow through GW material
•No landside slope breakout
•Low head differential across GW
•GW underlain by non-erodible ML (c'=100
psf)
•No known past performance issues related
to through seepage
N/A N/A Meets 2.13 1.92

37.62 37.57
Analysis Reference
Report
Waterside Drawdown
Factors of Safety
6 Total
Head at
the
Ground
Surface
(ft)
Bottom
of
Blanket
Elevation
(ft)
Underseepage Gradients
200-year WSE
Underseepage Gradients

HTOL WSE
Through Seepage Considerations and
Breakout Height above LS Toe (ft)
Landside Stability
Factors of Safety5
N/A
•Flow through SP-SM material
•Low breakout height
•No known past performance issues related
to through seepage

0.1 1.0 Meets 2.98 2.53 1.20 34.62

1.47 1.45 1.76 35.36

1.20 N/A
Reach
Analysis
Cross Section
Station Evaluated Condition
EFSM
(GEI/HDR, 2016)
1096+00
(Reach 4-1)
Cutoff Wall
to El. -77 and Existing
Relief Modifications
Contract 2 DDR
(GEI/HDR, 2020)
5 1104+00
(Reach 5-1)
Existing Conditions
Contract 2 DDR
(GEI/HDR, 2020)
Contract 2 DDR
(GEI/HDR, 2020)
6 32.14 35.13

32.02 35.00

32.01 35.00

35.49 37.70

31.89 34.87
Analysis Results from Referenced Report

Page 1 of 7 ends

Table C-1. Seepage and Stability Analysis Results Summary Bot. of
Blanket
Total
Head (ft) Gradient3
Allowable
Gradient
Bot. of
Blanket
Total
Head (ft) Gradient3
Allowable
Gradient Considerations for Through Seepage
Breakout
200-year
WSE
Breakout
HTOL
WSE
Meets TS
Criteria?
200-year
WSE
HTOL
WSE
22 ft Total
Flood
Drawdown
(TFD)
8 ft Rapid
Drawdown
(RD)
7 200-yr HTOL 200-yr HTOL
2024 ULDC WSEs
(ft)
Gradient Calculation Location X (ft)¹ D (ft)²
Analysis
WSEs (ft)
Analysis Reference
Report
Waterside Drawdown
Factors of Safety
6 Total
Head at
the
Ground
Surface
(ft)
Bottom
of
Blanket
Elevation
(ft)
Underseepage Gradients
200-year WSE
Underseepage Gradients

7.4 10.8 Meets 2.40 2.01 1.59 N/A 33.32 36.32 31.19 34.12 9 1204+00
EFSM
(GEI/HDR, 2016)
Cutoff wall to
El. -40 ft.

Landside Toe (Layer 3) 72 0 14.93 -9.00 22.22 0.30 0.50 22.97 0.34 0.60 •Flow cut off by cutoff wall to El. -40 ft 0.0 0.0 Meets 1.46 1.46 1.43 N/A 34.00 36.00 31.09 34.01 1287+00
EFSM
(GEI/HDR, 2016)
Cutoff wall to
El. -90 ft.

Landside Toe (Layer 3) 65 0 21.65 8.33 20.53 <0.01 0.50 20.92 <0.01 0.60 •Flow cut off by cutoff wall to El. -90 ft 0.1 0.2 Meets 1.97 1.96 1.70 N/A 33.28 35.28 30.38 33.25 Landside Toe (Layer 3) 68 0 22.25 9.00 19.60 <0.01 0.50 19.64 <0.01 0.60 Landside Depression 1 (Layer 3) 85 17 21.10 9.00 19.60 <0.01 0.53 19.64 <0.01 0.63 Landside Toe (Layer 2) 55 0 22.65 12.58 19.82 <0.01 0.50 20.06 <0.01 0.60 Landside Depression 1 (Layer 2) 178 123 19.31 11.47 18.79 <0.01 0.75 18.96 <0.01 0.85 Landside Toe (Layer 2) 54 0 20.16 1.18 24.70 0.24 0.50 25.55 0.28 0.60 Landside Depression 1 (Layer 2) 168 114 17.51 -2.88 24.46 0.34 0.73 25.28 0.38 0.83 1306+19
(Reach 13b)
EFSM
(GEI/HDR, 2016)
Cutoff wall to
El. -30 ft.

Landside Toe (Layer 2) 63 0 19.91 -1.73 30.11 0.47 0.50 31.67 0.54 0.60 •Flow through SP-SM material
•Stitched embankment USACE cutoff wall
•Low breakout height
•No post-USACE-wall past performance
issues related to through seepage

0.2 0.2 Meets --
8 --
8 --
8 --
8 33.18 35.18 30.24 33.09

1.43 8
1185+25
•Stitched embankment USACE cutoff wall
•No landside breakout
N/A N/A Meets 1.93 1.93
1137+00
(Reach 7-2b)
7 •Flow through SP-SM material
•No landside slope breakout
•Stitched embankment USACE cutoff wall
•No USACE post-wall performance issues
related to through seepage
N/A N/A Meets

1.40 (1.28)
1128+00
(Reach 7-2a)
•Flow through SM material
•Stitched embankment USACE cutoff wall
•Low breakout height
•No USACE post-wall performance issues
related to through seepage

0.2 0.2 Meets >1.4
12 --
8 1304+27
(Reach 13b)
Cutoff wall to
El. -30 ft.
•Flow through SP material
•Stitched embankment USACE cutoff wall
•Low breakout height
•No post-USACE-wall past performance
issues related to through seepage

0.0 0.0 Meets --
8 33.25 35.25
Meets 1.76 1.76 1.52 N/A
1294+95
(Reach 13a)
Cutoff wall to
El. -65 ft.
•Flow through SP-SM material
•Stitched embankment USACE cutoff wall
•No landside slope breakout (200-year) or
Low breakout height (HTOL)
•No post-USACE-wall past performance
issues related to through seepage
N/A 0.0
1289+00 Meets 1.91 1.91 1.36 N/A
Cutoff wall to
El. -90 ft.
•Flow cut off by cutoff wall to El. -90 ft 0.1 0.2
EFSM
(GEI/HDR, 2016)

35.17 Existing Conditions 33.35 36.35
EFSM
(GEI/HDR, 2016)
Existing Conditions 33.79 36.79
EFSM
(GEI/HDR, 2016)

1.38 N/A
>1.4 1.65 N/A

1.28 33.17

1.21 -- 33.16 35.16 8--
8 Seepage Berm
Contract 1 DDR
(GEI/HDR, 2019c)
Contract 1 DDR
(GEI/HDR, 2019c)
EFSM
(GEI/HDR, 2016)

35.08 31.73 34.70 37.08

31.64 34.60

31.25 34.19

30.36 33.24

30.32 33.19

30.25 33.11
13

Page 2 of 7 ends

HTOL WSE
Through Seepage Considerations and
Breakout Height above LS Toe (ft)
Landside Stability
Factors of Safety5
Reach
Analysis
Cross Section
Station Evaluated Condition
Analysis Results from Referenced Report
Landside Toe (Layer 2) 56 0 23.23 -0.91 30.08 0.28 0.50 31.61 0.35 0.60 Landside Depression 1 (Layer 2) 117 61 21.03 -3.21 29.56 0.35 0.62 31.02 0.41 0.72 Landside Depression 2 (Layer 2) 274 218 17.37 -8.68 28.09 0.41 0.80 29.35 0.46 0.90 Landside Toe (Layer 3) 60 0 21.31 -1.42 26.96 0.25 0.50 28.73 0.33 0.60 Landside Depression 1 (Layer 3) 67 7 20.85 -1.18 26.89 0.27 0.51 28.65 0.35 0.61 Landside Depression 2 (Layer 3) 170 110 20.07 -5.32 26.34 0.25 0.72 28.05 0.31 0.82 Landside Toe (Layer 2) 57 0 21.61 -2.67 28.33 0.28 0.50 30.76 0.38 0.60 Landside Depression 1 (Layer 2) 76 19 21.27 1.39 28.02 0.34 0.54 30.40 0.46 0.64 Landside Depression 2 (Layer 2) 128 71 18.19 0.85 27.42 0.53 0.64 29.73 0.67 0.74 Landside Toe (Layer 2) 49 0 19.77 -0.37 27.12 0.36 0.50 29.10 0.46 0.60 Landside Depression 1 (Layer 2) 85 36 18.79 1.16 26.18 0.42 0.57 27.98 0.52 0.67 Landside Depression 2 (Layer 2) 182 133 18.71 3.40 24.10 0.35 0.77 25.52 0.45 0.87 Landside Toe (Layer 2) 68 0 20.90 11.50 18.04 0 0.50 18.22 0 0.60 Landside Depression 1 (Layer 2) 110 42 20.13 11.50 17.92 0 0.58 18.09 0 0.68 Landside Depression 2 (Layer 2) 180 112 18.76 11.50 17.63 0 0.72 17.77 0 0.82 Landside Toe (Layers 2-3) 68 0 20.90 -0.61 21.49 0.03 0.50 22.15 0.06 0.60 Landside Depression 1 (Layers 2-3) 110 42 20.13 -0.61 21.18 0.05 0.58 21.81 0.08 0.68 Landside Depression 2 (Layers 2-3) 180 112 18.76 -0.61 20.70 0.10 0.72 21.27 0.13 0.82 Landside Toe (Layer 2) 57 0 19.53 5.79 24.18 0.34 0.50 24.98 0.40 0.60 Landside Depression (Layer 2) 156 99 19.12 5.79 23.09 0.30 0.70 23.77 0.35 0.80 Landside Toe (Layer 2) 48 0 20.76 14.07 21.02 0.04 0.50 21.07 0.05 0.60 Landside Toe (Layers 2-3) 48 0 20.76 8.52 23.84 0.25 0.50 24.54 0.31 0.60 14 Contract 2 DDR
(GEI/HDR, 2020)
Existing Conditions
1354+50 -- -- --
•Flow through SM material
•Stitched blanket cutoff wall
•Low breakout height
•Post-USACE-wall past performance issues
in Reach 15 were noted downstream of
1361+00, including seepage at LS toe, and
do not pertain to this analysis section

0.4 0.4 Meets --
Contract 2 DDR
(GEI/HDR, 2020)
1352+25 1.83 1.79 1.33 N/A
•Flow through SP material
•Stitched blanket cutoff wall
•Low breakout height
•Post-USACE-wall past performance issues
in Reach 15 were noted downstream of
1361+00, including seepage at LS toe, and
do not pertain to this analysis section

0.5 0.5 Meets
Contract 2 DDR
(GEI/HDR, 2020)
1348+25 -- -- -- --
Cutoff wall to
El. -25 ft.
•Flow through SP material
•Stitched blanket cutoff wall
•Breakout beyond the toe
•Post-USACE-wall past performance issues
in Reach 15 were noted downstream of
1361+00, including seepage at LS toe, and
do not pertain to this analysis section
N/A N/A Meets

32.38 35.38
1332+48 1.46
•Flow through Sandy ML material
•Material is non-erodible (c'>0)
•Stitched embankment USACE cutoff wall
•Low head differential
•No observed post-USACE-wall past
performance issues

0.2 0.2 Meets 1.79 1.79 1.14
Contract 2 DDR
(GEI/HDR, 2020)
Existing Conditions 32.34 35.34
1327+00 1.25 N/A
•Stitched embankment USACE cutoff wall
•Low breakout height
•No post-USACE-wall past performance
issues

1.5 1.8 Meets 1.63 1.54

1.73 1.54
Contract 2 DDR
(GEI/HDR, 2020)
1312+00 Existing Conditions N/A 32.45 35.45
•Flow through SM material
•Stitched embankment USACE cutoff wall
•Low breakout height
•No post-USACE-wall past performance
issues

1.2 1.2 Meets 1.73
--
8 --
8 --
8 1308+60
(Reach 13b)
Cutoff wall to
El. -30 ft.
•Flow through SP-SM material
•Stitched embankment USACE cutoff wall
•Low breakout height
•No post-USACE-wall past performance
issues related to through seepage

0.0 0.0 Meets --
8 33.20 35.20

32.60 34.60
Cutoff wall to
El. -35 ft.

Contract 2 DDR
(GEI/HDR, 2020)

32.69 34.69

32.63 34.63
Cutoff wall to
El. -35 ft.

EFSM
(GEI/HDR, 2016)

32.64 29.80 32.61

30.21 33.06

30.18 33.03

30.06 32.90

29.82 13
15 30.02 32.86

29.87 32.68

Page 3 of 7 ends

HTOL WSE
Through Seepage Considerations and
Breakout Height above LS Toe (ft)
Landside Stability
Factors of Safety5
Reach
Analysis
Cross Section
Station Evaluated Condition
Analysis Results from Referenced Report
Landside Toe (Layer 3) 46 0 21.69 8.60 23.22 0.12 0.50 23.67 0.15 0.60 Landside Depression 1 (Layer 3) 50 4 21.56 8.62 23.09 0.12 0.51 23.52 0.15 0.61 Landside Depression 2 (Layer 3) 193 147 17.02 3.27 20.07 0.22 0.79 20.35 0.24 0.89 Landside Toe (Layer 3) 41 0 20.73 8.58 25.64 0.40 0.50 26.70 0.49 0.60 Landside Depression 1 (Layer 3) 54 13 19.80 8.60 25.39 0.50 0.53 26.43 0.59 0.63 Landside Depression 2 (Layer 3) 194 152 17.40 8.01 23.35 0.63 0.80 24.23 0.73 0.90 Landside Toe (Layer 3) 44 0 20.83 4.03 26.92 0.36 0.50 28.28 0.44 0.60 Landside Depression 1 (Layer 3) 56 12 19.77 3.74 26.78 0.44 0.52 28.13 0.52 0.62 Landside Depression 2 (Layer 3) 97 53 19.14 4.01 26.22 0.47 0.61 27.52 0.55 0.71 Landside Depression 3 (Layer 3) 198 154 16.07 4.65 24.62 0.75 0.80 25.77 0.85 0.90 Landside Toe (Layer 3) 46 0 20.59 4.09 25.00 0.27 0.50 26.10 0.33 0.60 Landside Depression 1 (Layer 3) 92 46 19.35 5.36 24.55 0.37 0.59 25.60 0.45 0.69 Landside Depression 2 (Layer 3) 202 156 16.19 8.39 23.25 0.74 9 0.80 24.18 0.91 9 0.90 Landside Toe (Layer 3) 40 0 22.79 3.93 26.71 0.21 0.50 27.95 0.27 0.60 Landside Depression 1 (Layer 3) 70 30 20.68 4.75 26.43 0.36 0.56 27.64 0.44 0.66 Landside Depression 2 (Layer 3) 190 150 20.23 8.06 24.99 0.39 0.80 26.05 0.48 0.90 Landside Depression 3 (Layer 3) 219 179 17.73 8.89 24.55 0.77 0.80 25.57 0.89 0.90 Landside Toe (Layers 3-4A) 42 0 24.09 10.92 26.29 0.17 0.50 27.19 0.24 0.60 Landside Depression 1 (Layers 3-4A) 83 41 24.30 11.11 26.01 0.13 0.58 26.89 0.20 0.68 Landside Depression 2 (Layers 3-4A) 156 114 21.30 11.47 25.04 0.38 0.73 25.85 0.46 0.83 Landside Toe (Layers 3-4B) 42 0 24.09 5.90 26.49 0.13 0.50 27.47 0.19 0.60 Landside Depression 1 (Layers 3-4B) 83 41 24.30 5.93 26.21 0.10 0.58 27.17 0.16 0.68 Landside Depression 2 (Layers 3-4B) 156 114 21.30 5.98 25.50 0.27 0.73 26.41 0.33 0.83 1369+50
•Flow through SM and SW-SM embankment
material
•Stitched blanket cutoff wall
•Low breakout height
•Post-USACE-wall past performance issues
include seepage at LS toe

0.1 0.1
Contract 2 DDR
(GEI/HDR, 2020)
Cutoff wall to
El. -45 ft.

32.47 1.65 1.60 1.18
Contract 2 DDR
(GEI/HDR, 2020)
Cutoff wall to
El. -45 ft.

32.50 Meets -- -- --

34.50 1367+25 --
•Flow through SM and SP embankment
material
•Stitched blanket cutoff wall
•Low breakout height
•Post-USACE-wall past performance issues
include seepage at LS toe

0.0 0.0 Meets -- -- --

32.49 34.49
Cutoff wall to
El. -62 ft.

Contract 2 DDR
(GEI/HDR, 2020)
1358+50 -- --
•Flow through SM embankment material
•Stitched blanket cutoff wall
•Low breakout height
•Post-USACE-wall past performance issues
in Reach 15 were noted downstream of
1361+00, including seepage at LS toe, and
do not pertain to this analysis section

1.6 2.3 Meets -- --
-- --
Contract 2 DDR
(GEI/HDR, 2020)
Cutoff wall to
El. -35 ft.

32.55 34.55
Contract 2 DDR
(GEI/HDR, 2020)

32.52 34.52
•Flow through SM and SP embankment
material
•Stitched blanket cutoff wall
•Breakout ~1,650 ft beyond landside toe
•Post-USACE-wall past performance issues
in Reach 15 were noted downstream of
1361+00, including seepage at LS toe, and
do not pertain to this analysis section
N/A N/A Meets
Contract 2 DDR
(GEI/HDR, 2020)
Cutoff wall to
El. -45 ft.

32.48 34.48
-- --
•Flow through SM and SP embankment
material
•Stitched blanket cutoff wall
•Low breakout height
•Post-USACE-wall past performance issues
include seepage at LS toe

0.0 0.0 Meets -- -- -- --

1.27 •Flow through SM and SP embankment
material
•Stitched blanket cutoff wall
•Low breakout height
•Post-USACE-wall past performance issues
include seepage at LS toe

0.0 0.0 Meets
-- 34.47
1360+37
Cutoff wall to
El. -45 ft.
1365+00
1362+75

29.77 32.57
15 29.75 32.55

29.72 32.52

29.70 32.50

29.69 32.48

29.67 32.47

Page 4 of 7 ends

HTOL WSE
Through Seepage Considerations and
Breakout Height above LS Toe (ft)
Landside Stability
Factors of Safety5
Reach
Analysis
Cross Section
Station Evaluated Condition
Analysis Results from Referenced Report
Landside Toe (Layer 2) 52 0 20.64 6.86 22.41 0.13 0.50 23.89 0.24 0.60 Landside Depression 1 (Layer 2) 119 67 19.69 7.00 21.94 0.18 0.63 22.93 0.26 0.73 Landside Depression 2 (Layer 2) 177 125 16.60 7.00 21.40 0.50 0.75 22.35 0.60 0.85 Landside Toe (Layers 2-3) 52 0 20.64 -10.08 22.46 0.06 0.50 23.60 0.10 0.60 Landside Depression 1 (Layers 2-3) 119 67 19.69 -1.96 22.24 0.12 0.63 23.36 0.17 0.73 Landside Depression 2 (Layers 2-3) 177 125 16.60 -1.96 22.01 0.29 0.75 23.11 0.35 0.85 Landside Toe (Layer 2) 89 0 18.90 -8.89 29.43 0.38 0.50 31.11 0.44 0.60 Landside Depression 1 (Layer 2) 108 19 18.60 -8.25 29.28 0.40 0.54 30.94 0.46 0.64 Landside Depression 2 (Layer 2) 170 81 19.54 -6.00 28.76 0.36 0.66 30.36 0.42 0.76 Landside Embankment Toe (Layer 3) 35 0 31.28 3.78 28.70 0 0.50 30.23 0 0.60 Landside Berm Toe (Layer 3) 135 101 25.21 3.46 28.03 0 0.70 29.49 0 0.80 150 ft away from Landside Embankment
Toe (Layer 3)
185 150 24.38 3.20 27.70 0 0.80 29.12 0 0.90
Landside Embankment Toe (Layer 4) 35 0 31.28 -8.64 29.25 0 0.50 30.90 0 0.60 Landside Berm Toe (Layer 4) 135 101 25.21 -6.66 28.44 0 0.70 29.99 0 0.80 150 ft away from Landside Embankment
Toe (Layer 4)
185 150 24.38 -5.50 28.04 0 0.80 29.54 0 0.90
Landside Toe (Layer 2) 42 0 21.21 11.79 24.39 0.34 0.50 25.86 0.49 0.60 Landside Depression 1 (Layer 2) 95 53 20.24 9.14 24.25 0.36 0.61 25.70 0.49 0.71 19 1416+50
EFSM
(GEI/HDR, 2016)
Existing Conditions Landside Toe (Layer 2) 38 0 22.22 6.00 24.21 0.12 0.50 25.68 0.21 0.60 •SP-SM embankment material
•Keyed-in deep USACE cutoff wall
•No landside slope breakout
•No post-USACE-wall past performance
issues related to through seepage
N/A N/A Meets 1.77 1.77 1.55 N/A 31.47 34.35 29.29 32.06 Landside Toe (Layer 2A) 47 0 17.33 11.43 13.55 <0.01 0.50 13.91 <0.01 0.60 Landside Depression 1 (Layer 2A) 194 147 17.07 11.43 11.04 <0.01 0.79 11.54 <0.01 0.89 Landside Toe (Layers 2A-2B) 47 0 17.33 0.86 11.52 <0.01 0.50 12.03 <0.01 0.60 Landside Depression 1 (Layers 2A-2B) 194 147 17.07 2.50 11.04 <0.01 0.79 11.54 <0.01 0.89 18 1410+00 1.69 1.59 1.82 N/A
•SP-SM embankment material
•Deep USACE cutoff wall
•No landside slope breakout
•No post-USACE-wall past performance
issues related to through seepage

N/A N/A
EFSM
(GEI/HDR, 2016)
17 Contract 2 DDR
(GEI/HDR, 2020)
1538+31 0.0 Meets 1.94 1.94 1.47 N/A
Cutoff wall to
El. -105 ft.
•Flow through SP-SM material
•Stitched embankment USACE cutoff wall
•Low breakout height
•No post-wall past performance issues
related to through seepage
•Keyed-in proposed cutoff wall

0.0 Meets
16 1390+40
Cutoff wall to
El. -45 ft.
•Flow through Sandy ML material
•Material is non-erodible (c'>0)
•Stitched embankment USACE cutoff wall
•Low head differential
•Post-USACE-wall past performance issues
include numerous seepage reports
•Keyed-in proposed cutoff wall

2.2 2.2 Meets 32.41 34.41
Contract 2 DDR
(GEI/HDR, 2020)

1.89 1.83 1.37 N/A
Cutoff wall to
El. -50 ft.
•Flow through SM material
•Stitched embankment USACE cutoff wall
•Low breakout height
•Post-USACE-wall past performance issues
include numerous seepage reports
•Stitched blanket cutoff wall

0.7 0.7

1.20 N/A 32.29 34.29

32.22 34.22

31.12 33.12
Existing Conditions 31.61 34.53
Contract 2 DDR
(GEI/HDR, 2020)
1400+37
Cutoff wall to
El. -15 ft.
1406+25
•SM embankment material
•Low breakout height
•Stitched embankment USACE cutoff wall
•Post-USACE-wall past performance issues
include numerous seepage reports
•Stitched blanket cutoff wall

0.8 1.0 Meets 2.31 2.16
Contract 1 DDR
(GEI/HDR, 2019c)
Meets -- -- -- --
24 31.01

29.51 32.29

29.43 32.21

29.37 32.15

29.34 32.11

28.31

Page 5 of 7 ends

HTOL WSE
Through Seepage Considerations and
Breakout Height above LS Toe (ft)
Landside Stability
Factors of Safety5
Reach
Analysis
Cross Section
Station Evaluated Condition
Analysis Results from Referenced Report
Landside Toe (Layer 2A) 54 0 17.36 1.74 10.90 <0.01 0.50 11.26 <0.01 0.60 Landside Depression 1 (Layer 2A) 72 18 13.69 1.74 10.67 <0.01 0.54 11.03 <0.01 0.64 Landside Toe (Layers 2A-2B) 54 0 17.36 -6.08 10.47 <0.01 0.50 10.84 <0.01 0.60 Landside Depression 1 (Layers 2A-2B) 72 18 13.69 -5.65 10.45 <0.01 0.54 10.81 <0.01 0.64 Landside Toe (Layer 4A) 91 0 17.93 10.07 19.48 0.20 0.50 19.94 0.26 0.60 Landside Depression 1 (Layer 4A) 242 151 17.60 14.00 18.15 0.15 0.80 18.37 0.21 0.90 Landside Toe (Layers 4A-4B-4A) 91 0 17.93 3.25 19.78 0.13 0.50 20.38 0.17 0.60 Landside Depression 1 (Layers 4A-4B-4A) 242 151 17.60 3.50 18.84 0.09 0.80 19.37 0.13 0.90 Landside Toe (Layers 2A-2B) 49 0 20.00 2.39 25.87 0.33 0.50 27.35 0.42 0.60 Landside Depression 1 (Layers 2A-2B) 53 4 19.34 2.39 25.82 0.38 0.51 27.29 0.47 0.61 Landside Depression 2 (Layers 2A-2B) 71 21 18.58 2.45 25.56 0.43 0.54 27.01 0.52 0.64 Landside Depression 3 (Layers 2A-2B) 196 146 14.95 2.99 23.63 0.73 0.79 24.90 0.83 0.89 Landside Toe (Layers 2A-2B) 49 0 20.00 2.39 7.82 <0.01 0.50 8.08 <0.01 0.60 Landside Depression 1 (Layers 2A-2B) 53 4 19.34 2.39 7.81 <0.01 0.51 8.06 <0.01 0.61 Landside Depression 2 (Layers 2A-2B) 71 21 18.58 2.45 7.76 <0.01 0.54 8.01 <0.01 0.64 Landside Depression 3 (Layers 2A-2B) 196 146 14.95 2.99 7.47 <0.01 0.79 7.70 <0.01 0.89 Landside Depression 1 (Layers 2A-2B) 40 1 19.46 12.36 11.88 <0.01 0.50 12.31 <0.01 0.60 Landside Depression 1 (Layers 2A-3) 40 1 19.46 -4.07 10.10 <0.01 0.50 10.39 <0.01 0.60 Landside Depression 2 (Layers 2A-2B) 85 46 17.57 10.94 10.42 <0.01 0.59 10.73 <0.01 0.69 Landside Depression 2 (Layers 2A-3) 85 46 17.57 -4.88 10.03 <0.01 0.59 10.31 <0.01 0.69 Landside Depression 3 (Layers 2A-3) 204 165 15.46 -9.58 9.83 <0.01 0.80 10.09 <0.01 0.90 Landside Toe (Layer 3A) 52 0 16.90 7.85 13.21 <0.01 0.50 13.43 <0.01 0.60 Landside Toe (Layers 3A-4) 52 0 16.90 -9.18 10.16 <0.01 0.50 10.36 <0.01 0.60 Landside Depression 1 (Layer 3A) 74 22 15.96 6.60 11.49 <0.01 0.54 11.70 <0.01 0.64 Landside Depression 1 (Layers 3A-4) 74 22 15.96 -8.76 10.13 <0.01 0.54 10.33 <0.01 0.64

30.78 32.78
1561+00
Contract 1 DDR
(GEI/HDR, 2019c)
Cutoff wall to
El. -55 ft.

30.84 32.84
•Flow through SP-SM material
•Stitched embankment USACE cutoff wall
•No landside slope breakout
•Low head differential
•Post-USACE-wall past performance issues
include three seepage reports
•Keyed-in proposed cutoff wall
N/A N/A Meets

1.58 --
1565+50 1.58
Cutoff wall to
El. -55 ft.
•Flow through SP-SM material
•Keyed-in cutoff wall
•No landside slope breakout
•Post-USACE-wall past performance issues
include two seepage reports
•Keyed-in proposed cutoff wall
N/A N/A Meets

1.63 1.95 N/A
26 1561+00
Cutoff wall to
El. -10 ft.
•Flow through SP-SM material
•Stitched embankment USACE cutoff wall
•Low breakout height
•Low head differential
•Post-USACE-wall past performance issues
include three seepage reports
•Proposed cutoff wall stitches embankment
and blanket

0.0 0.0 Meets 1.64

1.71 N/A
25 1550+92
Cutoff wall to
El. -20 ft.
•Flow through SM material
•Stitched embankment USACE cutoff wall
•No post-USACE wall past performance
issues related to through seepage
•Keyed-in proposed cutoff wall

1.1 1.4 Meets 2.34
1544+30 1.34 N/A
Cutoff wall to
El. -60 ft.
•Flow through SM material
•Stitched embankment USACE cutoff wall
•No post-USACE wall past performance
issues related to through seepage
•Low breakout height
•Low head differential
•Keyed-in proposed cutoff wall

0.1 0.2 Meets

2.26 2.24 N/A
-- -- --

30.94 32.94

30.84 32.84
Contract 1 DDR
(GEI/HDR, 2019c)

31.04 33.04
Contract 1 DDR
(GEI/HDR, 2019c)
Contract 1 DDR
(GEI/HDR, 2019c)
Contract 1 DDR
(GEI/HDR, 2019c)
24 2.20 2.18
L-2 1579+77
Contract 1 DDR
(GEI/HDR, 2019c)
Cutoff wall to
El. -55 ft.

30.60 •Flow through SP-SM and SM material
•Keyed-in proposed cutoff wall

1.1 1.4 Meets 1.51 1.48 1.27 N/A 32.60

28.26 30.95

28.18 30.86

28.09 30.75

28.05 30.71

27.93 30.57

Page 6 of 7 ends

HTOL WSE
Through Seepage Considerations and
Breakout Height above LS Toe (ft)
Landside Stability
Factors of Safety5
Reach
Analysis
Cross Section
Station Evaluated Condition
Analysis Results from Referenced Report
Landside Toe (Layers 3A-3B) 56 0 16.40 -7.16 26.93 0.45 0.50 28.60 0.52 0.60 Landside Depression 1 (Layers 3A-3B) 63 8 15.86 -7.36 26.87 0.47 0.52 28.54 0.55 0.62 Landside Depression 2 (Layers 3A-3B) 199 144 13.10 -10.90 25.52 0.52 0.79 27.06 0.58 0.89 Landside Toe (Layer 4) 37 0 18.40 0.00 17.41 0.06 0.50 17.99 0.08 0.60 Landside Toe (Layers 4-5) 37 0 18.40 -15.52 17.30 0.03 0.50 17.91 0.04 0.60 Landside Depression 1 (Layer 4) 83 46 14.60 0.00 16.92 0.16 0.59 17.44 0.19 0.69 Landside Depression 1 (Layers 4-5) 83 46 14.60 -15.99 17.23 0.09 0.59 17.84 0.11 0.69 Notes:
1) X: Horizontal distance from the levee crown centerline alignment. 2) D: Horizontal distance from the landside levee toe. For extra wide-levees in Reaches 5 and 6, the distance is calculated based on the theoretical levee prism landside toe locations. 3) Gradients of "0" or <0.01 indicate a phreatic surface lower than the ground surface at gradient calculation location. 4) Under seepage gradients for leaker cases are calculated for either the upper 5 ft or the upper half of the leaker layer, whichever is lower. 8) Although cross section 1294+95 is upstream of Reach 13b, the stability analyses performed at 1294+95 are judged to be representative of conditions within Reach 13b. 9) For Station 1365+00 gradient calculations at Landside Depression 2 (approximately 156 feet from the landside toe), the gradients presented in the table have been extrapolated for the lower ULDC WSEs from the higher analysis WSEs. The analysis results in the DDR were noted to be conservative based on the blanket characterization. A sensitivity analysis presented in the DDR with the blanket characterized as silt (ML) rather than damaged/desiccated silty clay (CL-ML) lowered gradients at this location and met ULDC criteria. 5) The lowest calculated safety factors are given for all stability analyses. Two safety factors are reported where the lowest safety factor does not meet criteria, but (1) a slip surface with a safety factor equal to the criterion can be obtained for the landside slope, and (2) the remnant crown width between this slip surface and a slip surface meeting criteria for the 8-ft rapid drawdown stability analysis is at least 20 ft. In this case, the lowest calculated factor of safety for the landside slope is reported in parentheses. 7) The lowest calculated safety factors are given for all stability analyses. Two safety factors are reported where the lowest safety factor does not meet criteria, but (1) a slip surface with a safety factor equal to the criterion can be obtained for the waterside slope, and (2) the remnant crown width between this slip surface and a slip surface meeting criteria for the 200- year landside stability analysis is at least 20 ft. In this case, the lowest calculated factor of safety for the landside slope is reported in parentheses.

30.27 32.27
1639+79 1.61 1.12 1.47 30.22 32.22
Cutoff wall to
El. -55 ft.
•Flow through SM material
•No landside slope breakout
•Hanging USACE cutoff wall
•Post-USACE-wall past performance issues
include two seepage reports
•Proposed cutoff wall stitches embankment
and blanket
N/A N/A Meets 1.61

1.60 1.18 1.53
27 1627+50
Cutoff wall to
El. -55 ft.
•Flow through SP-SM material
•Low breakout height
•Hanging USACE cutoff wall
•Post-USACE-wall past performance issues
include seven seepage reports
•Proposed cutoff wall stitches embankment
and blanket

0.2 0.2 Meets 1.69
Contract 1 DDR
(GEI/HDR, 2019c)
Contract 1 DDR
(GEI/HDR, 2019c)

27.60 30.22
6) An initial screening was performed to evaluate cross-sections for a total flood drawdown of 22 feet from the 100-year WSE. Cross-sections with a calculated FS greater than 1.2 for the 22-foot drop were considered acceptable for rapid drawdown, and no further rapid drawdown evaluation was made for these sections. Cross-sections that have a factor of safety less than 1.2 for the 22-foot drop were evaluated for a rapid drawdown of 8 feet from the 100-year WSE.

27.65 30.27

Page 7 of 7 ends

ULDC Geotechnical Findings Report
American River South Levee System – Sacramento River East Levee April 2025
GEI Consultants, Inc.

Appendix D Levee Geometry
MBK Engineers Cross Section Evaluation
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 1 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 2 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 3 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 4 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 5 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 6 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 7 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 8 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 9 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 10 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 11 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 12 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 13 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 14 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 15 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 16 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 17 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 18 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 19 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 20 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 21 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 22 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 23 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 24 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 25 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 26 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 27 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 28 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 29 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 30 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 31 of 33
F:\SAFCA\FEMA_ULDC\FEMA\American South\geometry\ARS Levee Geometry - ULDC Dec 2024.docx DRAFT
American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 32 of 33
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American River South Levee System: Levee Geometry Analysis (ULDC) Profile Sheet No. 33 of 33
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Appendix E.

American River South ULDC
Due Diligence, Geotech - Kleinfelder
24001006.001A/SAC24R176178 Page i of vii April 17, 2025 © 2025 Kleinfelder
Copyright 2025 Kleinfelder
All Rights Reserved

ONLY THE CLIENT OR ITS DESIGNATED REPRESENTATIVES MAY USE THIS DOCUMENT AND ONLY FOR THE SPECIFIC PROJECT FOR WHICH THIS DATA REPORT WAS PREPARED.

ULDC GEOTECHNICAL FINDING

AMERICAN RIVER SOUTH LEVEE SYSTEM
SACRAMENTO RIVER EAST LEVEE STATIONS 1000+00 TO 1080+00, 1150+00 TO 1185+00, 1206+00 TO 1285+75, 1418+00 TO 1534+40, AND 1640+00 TO 1770+00

SACRAMENTO AREA FLOOD CONTROL AGENCY

SACRAMENTO COUNTY, CALIFORNIA
KLEINFELDER PROJECT # 24001006.001A
APRIL 17, 2025
24001006.001A/SAC24R176178 Page ii of vii April 17, 2025 © 2025 Kleinfelder
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p| 916.366.1701 April 17, 2025
File No.: 24001006.001A
Mr. Dan Tibbitts, PE
Principal Engineer
Sacramento Area Flood Control Agency
1325 J Street, Suite 1700
Sacramento, CA 95814
SUBJECT: ULDC Geotechnical Finding
Sacramento River East Levee Stations 1000+00 to 1080+00, 1150+00 to 1185+00, 1206+00 to 1285+75, 1418+00 to 1534+40, and 1640+00 to 1770+00 Sacramento Area Flood Control Agency
Sacramento County, California
Dear Mr. Tibbitts:

This report presents Kleinfelder’s geotechnical evaluation of the existing Sacramento River East Levee (SREL) in Sacramento County, California.

This geotechnical evaluation was performed for the Sacramento Area Flood Control Agency (SAFCA) to provide substantial evidence in the record to support a finding that the subject portions of the Sacramento River East Levee (SREL) within the American River South Levee System (ARSLS) study area meets the urban level of flood protection as defined by the California Department of Water Resources Urban Levee Design Criteria (ULDC) (DWR, 2012). This report contains Kleinfelder’s review and a professional opinion regarding whether the subject portions of SREL meet the geotechnical aspects of the ULDC (DWR, 2012) (soil sampling, testing, and logging; slope stability for intermittently loaded levees; underseepage for intermittently loaded levees; seismic vulnerability; levee geometry; interfaces and transitions; and floodwalls, retaining walls, and closure structures).

Other sections of the ULDC (DWR, 2012) are not addressed in this letter and are being addressed by other consultants.
24001006.001A/SAC24R176178 Page iii of vii April 17, 2025 © 2025 Kleinfelder
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p| 916.366.1701 If you have questions regarding this report or if we may be of further assistance, please contact the undersigned.

Sincerely,
KLEINFELDER, INC.

Ryan Hochstatter, EIT Meredith Beswick
Staff Engineer Principal Engineer
Reviewed By:

Timothy A. Williams, PE, GE
Sr. Principal Geotechnical Engineer
CC: Mr. Pro Mitra, PE/MBK Engineers ([email protected]) Ms. Becky Money, PE/MBK Engineers ([email protected]) 24001006.001A/SAC24R176178 Page iv of vii April 17, 2025 © 2025 Kleinfelder

TABLE OF CONTENTS

SECTION PAGE
1 INTRODUCTION .....................................................................................................................1

1.1 PROJECT BACKGROUND...................................................................................................... 1

1.2 PROJECT STATIONING AND DATUMS ................................................................................. 2

1.3 BACKGROUND AND CONSTRUCTION HISTORY................................................................... 2

1.3.1 SREL-A Construction History (Station 1000+00 to 1080+00)................................. 3

1.3.2 SREL-B Construction History (Station 1150+00 to 1185+00)................................. 3

1.3.3 SREL-C Construction History (Station 1206+00 to 1285+75)................................. 3

1.3.4 SREL-D Construction History (Station 1418+00 to 1534+40)................................. 4

1.3.5 SREL-E Construction History (Station 1640+00 to 1770+00)................................. 5

1.4 METHODOLOGY .................................................................................................................. 6

1.5 REFERENCED REPORTS........................................................................................................ 6

1.6 CRITERIA.............................................................................................................................. 8

1.7 WATER SURFACE ELEVATIONS............................................................................................ 9 2 ULDC GEOTECHNICAL CRITERIA REVIEW ...............................................................................10

2.1 ULDC SECTION 7.3 SOIL SAMPLING, TESTING, AND LOGGING......................................... 10

2.1.1 Conclusion............................................................................................................ 16

2.2 ULDC SECTION 7.4 SLOPE STABILITY FOR INTERMITTENTLY LOADED LEVEES.................. 16

2.2.1 Conclusion............................................................................................................ 23

2.3 ULDC SECTION 7.5 UNDERSEEPAGE FOR INTERMITTENTLY LOADED LEVEES .................. 23

2.3.1 Interstate 5 Depressed Section............................................................................ 28

2.3.2 Geotechnical Evaluation of Swimming Pools at or Near the Landside Toe......... 29

2.3.3 Conclusion............................................................................................................ 32

2.4 ULDC SECTION 7.7 SEISMIC VULNERABILITY .................................................................... 32

2.4.1 Conclusion............................................................................................................ 34

2.5 ULDC SECTION 7.8 LEVEE GEOMETRY............................................................................... 34

2.5.1 Geotechnical Review of Levee Geometry............................................................ 35

2.5.2 Conclusion............................................................................................................ 38

2.6 ULDC SECTION 7.9 INTERFACES AND TRANSITIONS ......................................................... 38

2.6.1 Levee Improvement Transitions.......................................................................... 38

2.6.2 Encroachment Interfaces..................................................................................... 42

2.6.3 Transition Between American River South Levee and Sacramento River East Levee at Station 1000+00............................................................................................... 46

2.6.4 Transition Between Sacramento River East Levee and Beach Lake North Levee at Station 1770+00................................................................................................... 47

2.6.5 Conclusion............................................................................................................ 47

2.7 ULDC SECTION 7.14 FLOODWALLS, RETAINING WALLS, AND CLOSURE STRUCTURES..... 48

2.7.1 Waterside Concrete Retaining Wall, Stations 1023+30 to 1024+70 ................... 48

2.7.2 Old Sacramento Floodwall and Riverwalk Promenade, Station 1040+90 to 1082+40 ............................................................................................................... 48

2.7.3 Cliff’s Marina Floodwall and Flashboard Closure, Stations 1765+92 to 1772+9050

2.7.4 Conclusion............................................................................................................ 51 3 AMERICAN RIVER SOUTH LEVEE SYSTEM STUDY AREA SUMMARY OF RESULTS......................52 24001006.001A/SAC24R176178 Page v of vii April 17, 2025 © 2025 Kleinfelder
4 LIMITATIONS .......................................................................................................................53 5 REFERENCES ........................................................................................................................55 TABLES

1.1 Water Surface Elevation Reference Summary

2.1 Summary of Exploration Locations and Spacing for SREL-A (Station 1000+00 to 1080+00)

2.2 Summary of Exploration Locations and Spacing for SREL-B (Station 1150+00 to 1185+00)

2.3 Summary of Exploration Locations and Spacing for SREL-C (Station 1206+00 to 1285+75)

2.4 Summary of Exploration Locations and Spacing for SREL-D (Station 1418+00 to 1534+40)

2.5 Summary of Exploration Locations and Spacing for SREL-E (Station 1640+00 to 1770+00)

2.6 Stability Analyses Comparison Summary

2.7 Seepage Analyses Comparison Summary

2.8 Swimming Pools Geotechnical Underseepage Evaluation

2.9 Seismic Vulnerability Classifications for American River South Levee System

2.10 SREL Levee Crown and Landside Toe Reference Summary

2.11 Levee Improvement Transitions

2.12 Bridge Pile Encroachments Within the ARSLS

3.1 Levee Reaches Meeting Geotechnical Aspects of ULDC Criteria

FIGURES
Figure 1 American River South Levee System Site Vicinity Map Figure 2a American River South Levee System Site Location Map (Part 1 of 2) Figure 2b American River South Levee System Site Location Map (Part 2 of 2)

APPENDICES
A MBK Engineers, 2025. “Technical Memorandum: American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee” Dated April 9, 2025.

B Kleinfelder, 2025. “American River South Levee System Swimming Pools Evaluation.” Dated January 30, 2025.

C Kleinfelder, 2025. “Seismic Performance Summary Report, American River South Levee System, ULDC & FEMA Levee Certification Project, Sacramento Area Flood Control Agency Levee Systems, Sacramento County, California.” Dated April 16, 2025.

D MBK Engineers, 2024. “American River South Levee System: Levee Geometry Analysis (ULDC).” Dated December 2024.

E Mead & Hunt, 2025. “American River South Levee System Due Diligence Review for ULDC & FEMA Certification, Sacramento Area Levee Certification, Phase 3, Sacramento Area Flood Control Agency (SAFCA), Project Number R1941500-120265.09.” Dated April 15, 2025. 24001006.001A/SAC24R176178 Page vi of vii April 17, 2025 © 2025 Kleinfelder

REPORT ACRONYMS
200-yr 200-year median (i.e., flood recurrence period)
ARCF American River Common Features
ARSL American River South Levee
ARSLS American River South Levee System
BLNL Beach Lake North Levee
CESPK United States Army Corps of Engineers, Sacramento District CVFPB Central Valley Flood Protection Board
Depressed Section Interstate 5 Depressed Section
DMM Deep Mix Method
DWR California Department of Water Resources
EL Elevation
EWSE Evaluation Water Surface Elevation
FEMA Federal Emergency Management Agency
FOS Factor of Safety
GDWSE Geotechnical Design Water Surface Elevation
GEI GEI Consultants
GER Geotechnical Evaluation Report
HTOL Hydraulic Top of Levee
I-5 Interstate 5
LMA Levee Maintaining Agency
MBK MBK Engineers
NAVD88 North American Vertical Datum of 1988
RSS Riverfront Seal Slab
SAFCA Sacramento Area Flood Control Agency
SB Soil-Bentonite
SC Soil-Cement
SCB Soil-Cement-Bentonite
SCCB Slag Cement-Cement-Bentonite
SGAM Supplemental Geotechnical Analysis Memorandum
SOP Standard Operating Procedure
SPSR Seismic Performance Summary Report
SREL Sacramento River East Levee
SREL-A SREL From Station 1000+00 to Station 1080+00
SREL-B SREL From Station 1150+00 to Station 1185+00
SREL-C SREL From Station 1206+00 to Station 1285+75
SREL-D SREL From Station 1418+00 to Station 1534+40
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SREL-E SREL From Station 1640+00 to Station 1770+00
SRELIP Sacramento River East Levee Improvement Project
ULDC Urban Levee Design Criteria
ULE Urban Levee Evaluation
URS URS Corporation
USACE United States Army Corps of Engineers
WSE Water Surface Elevation
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1 INTRODUCTION
___________________________________________________________________________________

1.1 PROJECT BACKGROUND
This report presents Kleinfelder’s geotechnical evaluation of five different segments of the existing Sacramento River East Levee (SREL) downstream of the American River, from Stations 1000+00 to 1080+00, 1150+00 to 1185+00, 1206+00 to 1285+75, 1418+00 to 1534+40, and 1640+00 to 1770+00 in Sacramento County, California. The project location relative to cities, rivers, and existing roadways is shown on Figures 1 and 2.

This evaluation was performed for the Sacramento Area Flood Control Agency (SAFCA) to provide substantial evidence in the record with respect to support a finding the subject portions of the American River South Levee System (ARSLS) described above meet the geotechnical criteria within the California Department of Water Resources (DWR) Urban Levee Design Criteria (ULDC) (DWR, 2012). Other areas of ARSLS are being evaluated by GEI Consultants (GEI) and MBK Engineers (MBK).

This report contains Kleinfelder’s review and engineering opinion regarding whether the subject portions of SREL described above areas meet the geotechnical requirements of the ULDC (7.3 Soil Sampling, Testing, and Logging; 7.4 Slope Stability for Intermittently Loaded Levees; 7.5 Underseepage for Intermittently Loaded Levees; 7.7 Seismic Vulnerability1; 7.8 Levee Geometry; 7.9 Interfaces and Transitions; and 7.14 Floodwalls, Retaining Walls, and Closure Structures). Other sections of the ULDC are not addressed in this report and are being addressed by other consultants.

This report is based on current known conditions of the levee segments at this time. Conditions, information, criteria, and assumptions can change over time and affect the level of flood protection provided for a particular area. Additional study and work may be needed due to the passage of time and if ULDC requirements change. This report includes conclusions related to the geotechnical aspects of the levee segments. Conclusions are subject to the LIMITATIONS section of this report. 1 Section 7.7 Seismic Vulnerability was assessed for the complete ARSLS, which is consistent with Kleinfelder’s project scope. 24001006.001A/SAC24R176178 Page 2 of 57 April 17, 2025
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1.2 PROJECT STATIONING AND DATUMS
Elevation references in this report are in feet and are based on the North American Vertical Datum of 1988 (NAVD88). Project stationing used in this report is based on the DWR system developed for the Urban Levee Evaluation (ULE) project (URS, 2014).

Five separate segments of SREL are assessed in this report. These segments are referred to in this document as SREL-A through SREL-E for brevity and clarity. These labels are specific to this document and should not be confused with the American River Common Features (ARCF) sub reaches for SREL. The stationing for each segment is shown below.
• SREL-A (1.5 miles): Stations 1000+00 to 1080+00
• SREL-B (0.66 miles): Stations 1150+00 to 1185+00
• SREL-C (1.5 miles): Stations 1206+00 to 1285+75
• SREL-D (2.2 miles): Stations 1418+00 to 1534+40
• SREL-E (2.5 miles): Stations 1640+00 to 1770+00

1.3 BACKGROUND AND CONSTRUCTION HISTORY
SREL was constructed in the mid-nineteenth century after two large floods occurred along the Sacramento and American Rivers. Flood events in 1850 and 1862 spurred the construction of flood protection levees along portions of both banks of the Sacramento River, as well as re-alignment of the American River. Based on review of historical documents, SREL in the Natomas Basin and in the lower portion of the Sacramento River near the delta were constructed using clam shell and/or suction dredgers by excavating soil within the natural banks (i.e. the river channel) of the Sacramento River. It is assumed that the same approach was taken to construct the levee segments within the study area. This is considered likely due to the fact that the levee consists mostly of relatively clean sand with interbedded layers of silt. Clean sands are typically found within active river channels.

Levee improvements by the United States Army Corps of Engineers (USACE) involving construction of seepage cutoff walls started after the flood of 1986. This flood caused significant seeps and boils near the landside toe of the levee along the southern portion of the study area. USACE primarily constructed slurry seepage cutoff walls composed of soil, cement, and bentonite (SCB) using trench or direct mix methods (DMM) through the middle of the levee crown. A concrete gravity floodwall along the levee waterside from Station 1040+90 to 1082+40 involved more complex installation procedures, such as 24001006.001A/SAC24R176178 Page 3 of 57 April 17, 2025
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installing and grouting tieback and dead man anchors. Construction history for each sub reach segment is described in Sections 1.3.1 through 1.3.5.

1.3.1 SREL-A Construction History (Station 1000+00 to 1080+00) • In 2000, an SCB seepage cutoff wall was constructed by USACE from SREL Stations 1000+00 to 1009+50 as an extension of the American River South Levee (ARSL) cutoff wall project. The approximate tip elevation of this wall is at -40 feet (approximately 80 feet below the crown). • A concrete gravity floodwall was constructed in Old Sacramento by the Southern Pacific Railroad in 1913 from Station 1040+00 to 1060+50. The City of Sacramento performed various improvements to and expansions of this floodwall up to Station 1082+40; the construction history of the Old Sacramento floodwall is detailed in Section 2.7.2.

1.3.2 SREL-B Construction History (Station 1150+00 to 1185+00) • USACE Sacramento Urban Area Phase II construction was performed in 1991 and 1993 and consisted of a SCB seepage cutoff wall using the slurry trench method. The cutoff wall was constructed from about Station 1125+75 to Station 1225+00. The cutoff wall tip elevation was at approximately 16 to 18 feet (depth ranged from about 23 to 30 feet below the levee crown).

The location of the Phase II cutoff wall was typically between the center and about 4 feet either toward the landside or waterside hinge point of the crest

1.3.3 SREL-C Construction History (Station 1206+00 to 1285+75) • USACE Sacramento Urban Area Phase I construction was performed between 1990 and 1991 and consisted of a SCB seepage cutoff wall using the slurry trench method. Phase I consisted of a cutoff wall that started near Station 1244+00 and extended downstream to about Station 1353+00.
o Phase II construction included a SCB seepage cutoff wall in Station 1206+00 through 1225+00 (see Section 1.3.2).
• In 2005, an SCB DMM seepage cutoff wall was constructed by SAFCA in the Little Pocket between Stations 1261+53 and 1285+50. The cutoff wall tip elevation ranged from 24001006.001A/SAC24R176178 Page 4 of 57 April 17, 2025
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approximately Elevation -55 to -75 feet (depth varied from about 91 to 112 feet below the levee crest).
• In 2023 and 2024, under American River Common Features (ARCF) SREL Contract 4, a soilcement (SC) jet grout seepage cutoff wall was constructed from Station 1244+73 to 1247+60 and a SCB DMM seepage cutoff wall was constructed from Station 1247+60 to 1261+77. Both walls were constructed to Tip Elevation -30 feet (approximately 70 feet below the levee crest).

1.3.4 SREL-D Construction History (Station 1418+00 to 1534+40) • USACE Sacramento Urban Area Phase II construction consisted of a SCB seepage cutoff wall using the slurry trench method. The second reach of the cutoff wall from Station 1353+00 to about Station 1756+32 ranged from depth 17 to 30 feet below the levee crown (approximate tip Elevation +18 to +5). The location of the Phase II cutoff wall was typically between the center and about 4 feet either toward the landside or waterside hinge point of the crest o Phase II construction was interrupted by the development of cracks in the levee and slurry leakage at four locations, primarily on the waterside near the levee toe. The failing areas were assigned a site number: Site 1, Stations 1558+57 to 1563+75, Site 2, Stations 1569+25 to 1572+25, Site 3, Stations 1488+25 to 1496+75, and Site 4, Stations 1399+75 to 1404+25. The trench failures manifested as slurry seeps/boils discharged at discrete locations along the levee toe primarily on the waterside, and associated cracking developed on the crown and slopes of the levee. In several cases, this condition led to substantial slurry losses from the slurry trenches. Remediation measures of the slurry seeps/boils at these sites consisted of reinforcement of the levee foundation soils by placing a layer of geotextile and two layers of geogrid within recompacted, finegrained material. In the southern portion of Site 3, the developed cracks were more severe than at the other sites. Remediation in the southern portion of Site 3 included placement of additional reinforcement geotextile layers. A total of 5 layers of reinforcement were used for reconstruction. The bottom layer consisted of geotextile, placed at about Elevation 12 feet. The remaining layers were geogrid, placed at one-foot intervals above Elevation 12 feet with the top layer located at Elevation 16 feet. • During the 1986 and 1997 flood events in the Sacramento River numerous boils were observed adjacent to and within the unlined intake channel into the City of Sacramento Sump No. 132. In 2003, a SCB DMM cutoff wall was constructed by SAFCA between Stations 1530+42 and 24001006.001A/SAC24R176178 Page 5 of 57 April 17, 2025
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1534+64. The cutoff wall was constructed using deep mixing methods to approximate tip Elevation -73 feet to -78 feet (approximately 110 feet below the levee crest). The pipe conduits crossing the levee were cut and removed to facilitate construction of the cutoff wall. The pipes were replaced after construction of the cutoff wall was completed. In addition, 10 relief wells were installed to help relieve underseepage pressures surrounding the sump. The relief wells are located along the northern and southern portions of the sump and the unlined intake channel. The relief wells discharge into the channel leading into the sump. Compaction grouting was also performed surrounding the pumping plant to densify near surface soils that may have been affected by the seepage and boil activity.
• In 2006, an SCB DMM cutoff wall was constructed by USACE from Stations 1406+99 to 1424+51.

The cutoff wall tip elevation varied from -74 to -77 feet (about 107 to 110 feet below the levee crest).
• In 2022, under ARCF SREL Contract 3, approximately 2 miles of slag cement-cement-bentonite (SCCB), soil bentonite (SB) open-trench, and SCB DMM seepage cutoff walls were constructed between Stations 1424+50 and 1534+30, with tip elevations ranging from -51 to -110 feet (about 85 to 140 feet below the levee crest) (Maloney Odin Joint Venture, 2024). • In 2023 and 2024, under ARCF SREL Contract 4, a soil-cement jet grout seepage cutoff wall was constructed from Station 1531+05 to 1533+18 to Tip Elevation -105 feet (about 140 feet below the levee crest).

1.3.5 SREL-E Construction History (Station 1640+00 to 1770+00) • USACE Sacramento Urban Area Phase II construction consisted of a SCB seepage cutoff wall through Station 1756+32 (see Section 1.3.4).
• A shallow SCB cutoff wall was constructed by USACE in 2006 from Stations 1755+30 to 1770+50.

The cutoff wall was installed to about Tip Elevation -8 feet (approximately 40 feet below the levee crest).
• In 2007, two layers of sheet pile walls were installed by the Freeport Regional Water Authority at the water intake facility from Stations 1662+49 to 1668+75. Tip elevation of the sheet pile walls ranged from approximately -41 to -53 feet (approximately 74 feet below the levee crest). • In 2023 and 2024, the following improvements were performed under ARCF SREL Contract 4:
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o SCB DMM seepage cutoff wall constructed from Station 1770+35 to 1774+00, tip Elevation -15 feet (approximately 45 feet below the levee crest). o Stability Berm constructed from Station 1689+07 to 1690+00. o Embankment Raise at Stations 1675+63 to 1678+10.
o Curb wall constructed to Tip Elevation +28 feet at Stations 1678+35 to 1719+49, Stations 1722+48 to 1726+51, and Stations 1731+50 to 1765+92.
o Flood Wall Raise at Stations 1765+92 to 1770+46.

1.4 METHODOLOGY
Kleinfelder performed seepage and slope stability analyses at selected locations along the subject portions of the SREL study area. SREL analyses were documented in the Kleinfelder 2021 and 2023 Supplemental Geotechnical Analysis Memorandums (SGAM) for American River Common Features 2016 Sacramento River East Levee Contracts 3 and 4, respectively, and the Kleinfelder 2016 ULDC Geotechnical Results Summary for Sacramento River East Levee Downstream of American River. In addition, ULE evaluated SREL and published seepage and slope stability analyses in the 2014-2015 Geotechnical Evaluation Report for the Sacramento River Study Area.

MBK prepared new 200-year and Hydraulic Top of Levee (HTOL) Water Surface Elevations (WSEs) which are designated, 2025 200-Year and 2025 HTOL WSEs (MBK, 2025). The 2025 HTOL WSE is lower than the lowest WSE analyzed for the above referenced reports. The cross sections analyzed were critical locations based on stratigraphy and levee geometry. Therefore, this summary was developed by comparing the previous analysis results at the previous WSEs with the lower 2025 200-Year and 2025 HTOL WSEs. Since the existing analyses met project geotechnical criteria at the previous WSEs, the existing analyses were considered to also meet criteria at the lower 2025 200-Year and 2025 HTOL WSEs. This procedure is described in Section 2 of this report.

1.5 REFERENCED REPORTS
This report includes results from previous studies performed by GEI Consultants, HDR, Kleinfelder, and ULE for the subject portions of SREL. Kleinfelder has reviewed and used existing analyses from the following reports.
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• GEI/HDR. 2016. “Embankment and Foundation Stability Memorandum, Sacramento River East Levee Improvement Project, Sacramento County, California,” Dated August 2016. • Kleinfelder, 2013. “Problem Identification Report, Sacramento River East Levee Downstream of American River, SAFCA FEMA2Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, and Beach Lake Levee).” Dated August 21, 2013.
• Kleinfelder, 2016. “ULDC Geotechnical Results Summary, Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, and Beach Lake Levee).” Dated April 29, 2016.
• Kleinfelder, 2021. “Final – Revision 1, Supplemental Geotechnical Analysis Memorandum Contract 3 Reaches, American River Common Features 2016, Sacramento River East Levee, Contract 3.” Dated September 10, 2021.
• Kleinfelder, 2022. “Geotechnical Data Report, American River Common Features 2016, Sacramento River East Levee, Contracts 3 and 4, Sacramento County, California, Contract No.:

W91238-16D-0019, Task Order W91238-20-F-0080, USACE Project No.: 456852.” Issue Date May 24, 2021. Revised October 14, 2022.
• Kleinfelder, 2023. “Supplemental Geotechnical Analysis Memorandum Contract 4 Reaches, American River Common Features 2016, Sacramento River East Levee, Contract 4.” Dated January 26, 2023.
• MBK Engineers, 2025. “Technical Memorandum: American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee.” Dated April 9, 2025. • Mead & Hunt, 2025. “American River South Levee System Due Diligence Review for ULDC & FEMA Certification, Sacramento Area Levee Certification, Phase 3, Sacramento Area Flood Control Agency (SAFCA), Project Number R1941500-120265.09.” Dated April 15, 2025. 2 Federal Emergency Management Agency
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• URS, 2014. “Geotechnical Evaluation Report (GER), Volume 1, Existing Conditions, Sacramento River Study Area.” Dated July 2014.
• URS, 2015. “Geotechnical Evaluation Report, Volume 2, Remedial Alternatives, Sacramento River Study Area.” Dated January 2014.

In addition to the reports referenced above, Kleinfelder has reviewed the design and construction documents related to the SREL study areas only within the reaches being evaluated by Kleinfelder. These documents are contained in the list of references, which are included in Section 5 of this report.

1.6 CRITERIA
The purpose of this study was to review existing geotechnical information available for these levee segments to perform an evaluation as to whether these levees currently meet the geotechnical requirement of the ULDC. This information is contained in the reports referenced in Section 1.5. This information was compared to criteria from the following references:
• USACE EM 1110-2-1913 “Design and Construction of Levees,” dated April 30, 2000 • USACE EM 1110-2-1914 “Design, Construction, and Maintenance of Relief Wells,” dated March 7, 2025
• USACE EM 1110-2-2502 “Flood Walls and Other Hydraulic Retaining Walls,” dated August 1, 2022
• USACE ETL 1110-2-569 “Design Guidance for Levee Underseepage,” dated May 1, 2005 • USACE SPK-EDG, “Standard Operating Procedure 3, Geotechnical Levee Practice, US Army Corps of Engineers, Sacramento District, Geotechnical Engineering Branch” dated May 2022 • US Title 44 Code of Federal Regulations 65.10: Mapping of Areas Protected by Levee Systems, dated October 1, 2011
• Urban Levee Design Criteria (ULDC), State of California Department of Water Resources, dated May 2012
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1.7 WATER SURFACE ELEVATIONS
Water surface elevations were provided to Kleinfelder for the reports referenced in Section 1.5, above.

The following table lists these WSEs.

Table 1.1
Water Surface Elevation Reference Summary
Levee WSE Elevation Range
(NAVD88, ft) Source Date
SREL
ULE Geotechnical Evaluation Report (URS, 2014)
100-Year 28.6 – 35.2 Technical Memorandum titled
“Water Surface Elevations Used for
Geotechnical Analysis – Sacramento
Study Area,” Appendix C of GER
September
2013 200-Year 29.8 – 36.4
HTOL 32.8 – 39.4
ULDC Geotechnical Results Summary (Kleinfelder, 2016)
100-Year 27.16 – 34.38
MBK Engineers Table titled
“SREL WSE profiles - transmitted to
Kleinfelder 2-18-14.xls”
February
18, 2014 200-Year 27.92 – 36.43
HTOL 30.65 – 38.23
SGAMs USACE Contracts 3 & 4
DWSE
(200-Year) 28.21 – 35.23 MBK Engineers “Determination of the Design Water Surface Elevation
for the SAFCA Sacramento River East
Levee Improvement Project,” dated
September 14, 2016” Appendix A of
SGAM Reports.

September
14, 2016
Geotechnical
DWSE
(DWSE + 1 ft)

29.21 – 36.23
HTOL 31.13 – 38.23
ULDC Geotechnical Finding (MBK, 2025)
200-Year
DWSE 26.65 – 33.40
MBK Engineers “Technical
Memorandum: American River
South Levee System -
Determination of the Urban Levee
Design Criteria Design Water
Surface Elevation, Minimum Top of
Levee, and Hydraulic Top of Levee.”
April 9,
2025
HTOL 29.15 – 36.40
The 2025 200-year DWSE and HTOL WSEs (MBK, 2025) used for the current ULDC evaluation were provided in tabular form at 100-foot intervals along the ARSL and SREL. The 2025 200-year DWSE and HTOL WSEs (MBK, 2025) are included in Appendix A.
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2 ULDC GEOTECHNICAL CRITERIA REVIEW
___________________________________________________________________________________ Kleinfelder performed a review of existing reports and analyses contained in those reports referenced in Section 1.5, above. This review was performed to determine whether the subject portions of SREL meet the ULDC from a geotechnical perspective for the following sections. • 7.3 Soil Sampling, Testing, and Logging
• 7.4 Slope Stability for Intermittently Loaded Levees
• 7.5 Underseepage for Intermittently Loaded Levees
• 7.7 Seismic Vulnerability
• 7.8 Levee Geometry
• 7.9 Interfaces and Transitions
• 7.14 Floodwalls, Retaining Walls, and Closure Structures This evaluation includes a review of existing information referenced in this report and has not included performance of new analysis or field investigation. Where available, construction inspection records have also been reviewed.

The following sections of this report contain a summary of our analysis.

2.1 ULDC SECTION 7.3 SOIL SAMPLING, TESTING, AND LOGGING This section contains a summary of the review of existing information for the SREL-A through SREL-E segments with regards to ULDC Section 7.3 Soil Sampling, Testing, and Logging. The general requirements of this section are outlined below.

ULDC 7.3 requires soil sampling, testing, and logging per standard procedures prescribed in guidance documents, including the USACE Sacramento District’s (CESPK) Geotechnical Levee Practice Standard Operating Procedures (SOP) (USACE, 2022) and DWR’s Division of Flood Management Soil and Rock Logging, Classification, Description and Presentation Manual (2009). This includes an evaluation of soil exploration quantity and location as outlined in the CESPK SOP (USACE, 2022). Based on this document, explorations for a feasibility levee evaluation should be obtained at a spacing of approximately 1,000 feet along the levee crest. For preconstruction and design studies a spacing of approximately 500 feet along the waterside toe, levee crown, landside toe. Exploration depths should be a minimum of 4 times the levee height and extending to an appropriate stratum. 24001006.001A/SAC24R176178 Page 11 of 57 April 17, 2025 © 2025 Kleinfelder
Explorations that did not meet the requirements outlined (e.g., explorations that were not drilled deep enough) above were not included.

The CESPK 2022 SOP (USACE, 2022) recommends a thorough evaluation of existing information as part of a levee evaluation program. This includes a review of original construction (if available), improvements, performance history, existing subsurface information, and regional and local geomorphology. The standard also recommends the use of cone penetrometers (CPTs) and geophysics to supplement borings, where appropriate.

Based on the paraphrased requirements above, Kleinfelder interpreted the geotechnical guidance from the ULDC and SOP as the following:
• One exploration taken from the levee crown for every 500 feet of levee. • One exploration taken from the levee landside toe for every 500 feet of levee. • One exploration taken from the levee waterside toe for every 500 feet of levee. Waterside explorations may be omitted if site conditions prevent explorations from being conducted (site access is not possible, environmental issues, etc.)
• Landside field explorations are not included in the frequency specified by the ULDC Section 7.3 and CESPK 2022 SOP guidance. Kleinfelder included landside field borings in Tables 2.1 through

2.5 to illustrate relative spacing of explorations that were performed outside of the levee prism.

Additionally, each exploration was reviewed for laboratory testing performed on samples. Boring logs from as early as the late 1960s to as late as the early 2020s were considered to meet guidelines if they contained results for plasticity, dry unit weight, permeability, or other testing results that adequately characterized the logged material. The Kleinfelder Geotechnical Data Report for the ARCF SREL Contracts 3 and 4 projects (Kleinfelder, 2022), which contains explorations for the SREL-A through SRELE reaches, states the following testing procedures were used on the 29 explorations conducted for the projects in 2020:
• Moisture Content: ASTM D2216
• Dry Unit Weight: ASTM D7263 (Cal samplers) and ASTM D2937 (Shelby tubes) • Atterberg Limits: ASTM D4318
• Grain Size Analysis: ASTM D6913
• Permeability: ASTM D5084
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• Consolidated Drained Triaxial Compression: D7181
The geotechnical data report states that testing on previous explorations included moisture content, dry unit weight, Atterberg Limits, grain size analysis, hydrometer analysis, organic content, specific gravity, unconfined compressive strength, direct shear, consolidation, permeability, and triaxial shear tests. The report also states laboratory tests for these previous explorations were performed following similar standards, procedures, and level of care as those performed for the ARCF SREL projects (Kleinfelder, 2022).

Explorations were also evaluated for logging procedures. Although logging methods varied across borings (such as USACE and DWR methods), the methods used in the reviewed explorations were generally in accordance with ASTM D2488, which aligns with the appropriate field logging manual identified in the ULDC Section 7.3 guidance. Where available, the as-built plans, conformance laboratory tests, and in-place compaction tests for the construction and improvements of each levee were reviewed as part of the ULDC evaluation. This information was used to evaluate the levee geometry and material properties within the newly constructed and improved levee sections.

SREL-A from Stations 1000+00 to 1080+00 is approximately 1.5 miles (8,000 feet). SREL-B from Stations 1150+00 to 1185+00 is approximately 0.66 miles (3,500 feet). SREL-C from Stations 1206+00 to 1285+75 is approximately 1.5 miles (7,975 feet). SREL-D from Stations 1418+00 to 1534+40 is approximately 2.2 miles (11,640 feet). SREL-E from Stations 1640+00 to 1770+00 is approximately 2.46 miles (13,000 feet).

Total of the five segments in SREL is approximately 8.35 miles (44,115 feet) long.

The approximate number of explorations for each levee segment should be spaced apart on average by 500 feet for levee design. This applies to explorations taken from the waterside toe, levee crown, and landside toe individually (i.e. one levee crown exploration at Station 1000+00, then one levee crown exploration at Station 1005+00, then at 1010+00, etc.). Following this guideline, each segment should generally have the following quantities of valid explorations (approximately 33 explorations per mile):

1. SREL-A (1.5 miles): 16 explorations of each type (waterside toe, levee crown, landside toe) – 48 total explorations

2. SREL-B (0.66 miles): 7 explorations of each type - 21 total explorations

3. SREL-C (1.5 miles): 16 explorations of each type - 48 total explorations

5. SREL-E (2.5 miles): 27 explorations of each type - 81 total explorations SREL has been explored by Kleinfelder, DWR, USACE, and others for levee evaluations and improvement projects. Explorations include drilled borings and cone penetrometer soundings (CPT). The explorations reviewed by Kleinfelder included those advanced for the SAFCA FEMA Levee Accreditation program, the DWR ULE project, the SAFCA Sacramento River East Levee Improvement Project, various USACE SREL evaluation and improvement projects, explorations spaced along DMM alignments, and previous studies by others. To be included in the summary, the explorations were evaluated for depth (a minimum of 4 times the levee height for crest explorations and 3 times the levee height for toe and field explorations), sampling frequency, laboratory testing, and classification. For example, shallow borings that only assess the levee embankment were not included in the “Meets CESPK 2022 SOP” exploration count and spacing summaries.

Tables 2.1 through 2.5 below summarize the total number of explorations performed, total number of explorations that meet the exploration requirement described in the CESPK SOP (USACE, 2022), and total number of explorations required to meet ULDC Section 7.3 for each levee location.

Table 2.1
Summary of Exploration Locations and Spacing for SREL-A (Stations 1000+00 to 1080+00) Exploration
Location
Explorations that Meet CESPK
2022 SOP All Explorations ULDC Requirements
Number of
Explorations
Average
Spacing of
Explorations
(ft)
Number of
Explorations
Average
Spacing of
Explorations
(ft)
Explorations
Required to
Meet ULDC
Section 7.3
and CESPK
2022 SOP
Spacing
Required
to Meet
CESPK
2022 SOP
(ft)
Waterside
Toe*
5 1,282 9 719 16 500
Levee
Crown 15 307 29 272 16 500
Landside
Toe 7 1,092 14 548 16 500
Landside
Field 8 197 40 165 -- --
Total 35 92 48
Average
Per Mile 23 61 33
*Waterside explorations may be omitted due to environmental issues, site access, or other conditions preventing investigation. 24001006.001A/SAC24R176178 Page 14 of 57 April 17, 2025 © 2025 Kleinfelder
Table 2.2
Summary of Exploration Locations and Spacing for SREL-B (Stations 1150+00 to 1185+00) Exploration
Location
Explorations that Meet
CESPK 2022 SOP All Explorations ULDC Requirements
Number of
Explorations
Average
Spacing of
Explorations
(ft)
Number of
Explorations
Average
Spacing of
Explorations
(ft)
Explorations
Required to
Meet ULDC
Section 7.3
and CESPK
2022 SOP
Spacing
Required
to Meet
CESPK
2022 SOP
(ft)
Waterside
Toe*
0 -- 0 -- 7 500
Levee
Crown 5 557 10 307 7 500
Landside
Toe 1 2,026 2 1,013 7 500
Landside
Field 1 2,180 11 301 -- --
Total 7 23 21
Average Per
Mile 11 35 33
*Waterside explorations may be omitted due to environmental issues, site access, or other conditions preventing investigation.

Table 2.3
Summary of Exploration Locations and Spacing for SREL-C (Stations 1206+00 to 1285+75) Exploration
Location
Explorations that Meet CESPK
2022 SOP All Explorations ULDC Requirements
Number of
Explorations
Average
Spacing of
Explorations
(ft)
Number of
Explorations
Average
Spacing of
Explorations
(ft)
Explorations
Required to
Meet ULDC
Section 7.3 and
CESPK 2022 SOP
Spacing
Required
to Meet
CESPK
2022 SOP
(ft)
Waterside
Toe*
7 586 8 513 16 500
Levee
Crown 39 204 57 140 16 500
Landside
Toe 2 2,325 7 776 16 500
Landside
Field 2 2,319 21 382 -- --
Total 50 93 48
Average Per
Mile 33 62 33
*Waterside explorations may be omitted due to environmental issues, site access, or other conditions preventing investigation. 24001006.001A/SAC24R176178 Page 15 of 57 April 17, 2025 © 2025 Kleinfelder
Table 2.4
Summary of Exploration Locations and Spacing for SREL-D (Stations 1418+00 to 1534+40) Exploration
Location
Explorations that Meet
CESPK 2022 SOP All Explorations ULDC Requirements
Number of
Explorations
Average
Spacing of
Explorations
(ft)
Number of
Explorations
Average
Spacing of
Explorations (ft)
Explorations
Required to
Meet ULDC
Section 7.3
and CESPK
2022 SOP
Spacing
Required
to Meet
CESPK
2022 SOP
(ft)
Waterside
Toe*
0 -- 1 4,701 24 500
Levee
Crown 69 202 87 150 24 500
Landside
Toe 32 387 42 290 24 500
Landside
Field 11 749 29 674 -- --
Total 112 159 72
Average Per
Mile 51 72 33
*Waterside explorations may be omitted due to environmental issues, site access, or other conditions preventing investigation.

Table 2.5
Summary of Exploration Locations and Spacing for SREL-E (Stations 1640+00 to 1770+00) Exploration
Location
Explorations that Meet
CESPK 2022 SOP All Explorations ULDC Requirements
Number of
Explorations
Average
Spacing of
Explorations
(ft)
Number of
Explorations
Average
Spacing of
Explorations (ft)
Explorations
Required to
Meet ULDC
Section 7.3
and CESPK
2022 SOP
Spacing
Required
to Meet
CESPK
2022 SOP
(ft)
Waterside
Toe*
8 642 8 642 27 500
Levee
Crown 20 620 45 285 27 500
Landside
Toe 11 1,027 19 595 27 500
Landside
Field 17 498 23 538 -- --
Total 56 95 81
Average Per
Mile 23 39 33
*Waterside explorations may be omitted due to environmental issues, site access, or other conditions preventing investigation. 24001006.001A/SAC24R176178 Page 16 of 57 April 17, 2025 © 2025 Kleinfelder
It is noted that the total number of explorations is not within the recommended range of explorations in the CESPK 2022 SOP for levee crown, waterside toe, and landside toe borings (no quantity and spacing guidelines were noted for landside field borings, which lie outside the levee prism). While explorations not meeting the CESPK 2022 SOP requirements were not relied upon for analysis, the data was reviewed in conjunction with adjacent explorations that meet CESPK 2022 SOP requirements and were included as part of the “All Explorations” summary.

In addition, geology and geomorphology, geophysical HEM (helicopter-based electromagnetics surveys), past performance information, and historical records were also used to assess geotechnical conditions.

The geophysical HEM provides a continuous record of the subsurface conditions along the levee.

Construction as-builts and records were reviewed for the levee improvements since the 1990s. This included open trench slurry cutoff wall installation records.

2.1.1 Conclusion
Based on the above information, although the number of explorations does not match the recommendation from the CESPK 2022 SOP, it is Kleinfelder’s opinion that the subsurface explorations, laboratory testing on samples, geologic and geomorphologic mapping, cutoff wall observation, and continuous HEM data altogether provide an adequate assessment of the subsurface conditions for levee evaluation as outlined in the ULDC and CESPK SOP. The intent of an exploration program for a levee evaluation project is to adequately characterize subsurface conditions such that the levee can be evaluated and improvements, if needed, can be designed and constructed. It is Kleinfelder’s opinion that the frequency and quality of explorations for the SREL-A through SREL-E segments meet the intent of the guidance outlined above and meet the requirements of ULDC 7.3 for Soil Sampling, Testing, and Logging without exception.

2.2 ULDC SECTION 7.4 SLOPE STABILITY FOR INTERMITTENTLY LOADED LEVEES The section contains a summary of the review of the existing reports and analyses performed for SREL-A through SREL-E segments as it applies to ULDC Section 7.4 Slope Stability for Intermittently Loaded Levees. ULDC defines an intermittently loaded levee as:
24001006.001A/SAC24R176178 Page 17 of 57 April 17, 2025 © 2025 Kleinfelder
“Intermittently loaded levee means a levee that does not experience a water surface elevation of one foot or higher above the elevation of the levee toe at least once a day for more than 36 days per year on average.”
SREL segments are generally subject to short term flood events where the water rarely reaches the landside embankment toe. SREL-A through SREL-E are considered Intermittently Loaded Levees (URS, 2014).

The general requirements of ULDC Section 7.4 Slope Stability for Intermittently Loaded Levees are outlined below.

ULDC 7.4 requires slope stability analysis for the design water surface elevation (DWSE) and at the Hydraulic Top of Levee (HTOL) WSE. “Engineers should use sound engineering judgment and guidance from EM 1110-2-1902 to decide what constitutes a minor, insignificant slip surface versus a sliding surface that threatens the integrity of the levee.

These determinations should be based on performance history, levee geometry, type of levee fill material, stratigraphy of the levee embankment and foundation soils, seepage conditions (including pore water pressures calculated for the seepage analysis), soil strength characteristics, and potential for erosion. Those surfaces which significantly threaten the integrity of the levee must meet minimum slope stability criteria.” Steadystate landside stability and rapid drawdown waterside stability should be evaluated using the minimum factors of safety summarized in Table 1.

Stability Analysis ULDC Minimum Factor of Safety1
Steady-State DWSE, Landside Slope 1.4
Steady-State HTOL WSE, Landside Slope 1.2
Rapid Drawdown DWSE, Waterside Slope 1.0-1.22
End of Construction 1.33

1. Critical failure surface should intersect the levee crown and exceed a minimum of 3-foot depth into the level slope.

2. Minimum factor of safety dependent on time extent DWSE may have saturated the waterside levee slope.

3. End of Construction in performed for newly constructed levees Through seepage occurs where the phreatic seepage surface exits above the levee toe on the landside levee slope. For through seepage, reaches where the phreatic seepage surface exited on a levee slope that is composed of erodible material (sands and non-plastic silts and silty sands) were generally considered to not meet criteria.
24001006.001A/SAC24R176178 Page 18 of 57 April 17, 2025 © 2025 Kleinfelder
Detailed discussions of the slope stability analyses previously performed are discussed in the reports listed in Section 1.5 and included in the reference list. These analyses results were compared with the 2025 200-year and HTOL WSEs (MBK, 2025). Since the previously performed analyses were analyzed with a WSE that is above the 2025 200-year and HTOL WSEs and met slope stability criteria and soil and geometry conditions have not changed, the analyses are considered to meet criteria for the 2025 WSEs.

Table 2.6 contains the previously performed analysis results with the design WSE and the 2025 WSEs.

Footnotes elaborating upon criteria and results are listed at the end of the table. 24001006.001A/SAC24R176178 Page 19 of 57 April 17, 2025 © 2025 Kleinfelder
Table 2.6
Stability Analyses Comparison Summary
Analysis
Station Range
Approximate
ULE Station
Constructed
Remediation
Reference Report Summary 2025 ULDC Summary
Modeled
Remediation Report Reference
Highest
Previously
Modeled WSE
Meets/Does Not Meet
2025 WSE
(ft)
Difference 2025
WSE – Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
Through
Seepage1
Steady -State
Landside
Stability Factor
of Safety (FOS)
Rapid Drawdown
Waterside Stability
FOS 2,3
Through
Seepage1
SteadyState
Landside
Stability
Rapid
Drawdown
Waterside
Stability
1000+00 to
1080+00
1005+00 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

38.2 (HTOL) Meets Meets (2.21)
Meets (1.59)
200-yr WSE (35.2 ft)
to 27.2 ft

33.36 (200-yr)

36.36 (HTOL)
-4.84
-1.84
Meets Meets Meets
1011+00 Existing
Conditions
Existing
Conditions
2014 Sacramento River
ULE GER 39.4 (HTOL) Meets Meets (1.29)
Meets (1.29)
200-yr WSE (36.4 ft)
to 23.4 ft

33.30 (200-yr)

36.30 (HTOL)
-6.10
-3.10 Meets 4 Meets Meets
1029+50 Geometry
Correction
Geometry
Correction
January 26, 2023,
Supplemental
Geotechnical Analysis
Memorandum (SGAM)
SREL-4

38.1 (HTOL) Meets
Meets (1.55
base, 1.57
sensitivity)
Meets (1.25 base,

1.24 sensitivity)
GDWSE (36.1 ft) to

28.1 ft

33.04 (200-yr)

36.04 (HTOL)
-5.06
-2.06 Meets Meets Meets
1035+00 Geometry
Correction
Geometry
Correction
January 26, 2023, SGAM
SREL-4

38.0 (HTOL) Meets Meets (4.75)
Does Not Meet,
Accepted (0.83) 6
GDWSE (36.0 ft) to

28.0 ft

32.95 (200-yr)

35.95 (HTOL)
-5.05
-2.05 Meets Meets Accepted
5 1047+00 Existing
Conditions
Existing
Conditions
2014 Sacramento River
ULE GER 36.1 (200-yr)
Not Evaluated
Due to High
Ground
Not Evaluated
Due to High
Ground
Meets (1.23)
200-yr WSE (36.1 ft)
to 23.6 ft

32.54 (200-yr)

35.54 (HTOL)
-3.56
-0.56
Not
Evaluated
Not
Evaluated
Meets
1072+00 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

37.7 (HTOL) Meets Meets (1.60)9
Meets (1.32)
200-yr WSE (34.7 ft)
to 26.7 ft

32.34 (200-yr)

35.34 (HTOL)
-5.36
-2.36 Meets Meets
9 Meets
1073+00 Existing
Conditions
Existing
Conditions
2014 Sacramento River
ULE GER 36.9 (HTOL) Meets Meets (1.74) 9
Meets (1.19)
200-yr WSE (36.0 ft)
to 24.0 ft

32.33 (200-yr)

35.33 (HTOL)
-4.57
-1.57 Meets Meets
9 Meets
1150+00 to
1185+00
1160+00 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

36.5 (HTOL) Meets Meets (1.79)
Meets (1.28)
200-yr WSE (33.5 ft)
to 25.5 ft

31.48 (200-yr)

34.43 (HTOL)
-5.02
-2.07 Meets Meets Meets
1172+00 Existing
Conditions
Existing
Conditions (4
Sensitivities)
January 26, 2023, SGAM
SREL-4

36.2 (HTOL) Meets Meets (1.84 to

1.94)
Acceptable (1.09 to

1.17) 6
EWSE (33.5 ft) to

25.5 ft

31.37 (200-yr)

34.31 (HTOL)
-4.83
-1.89 Meets Meets Meets
1206+00 to
1285+75 1207+50 Existing Conditions
Existing
Conditions
January 26, 2023, SGAM
SREL-4

36.0 (HTOL) Meets Meets (1.45)
Meets (1.45)
EWSE (33.2 ft) to

25.2 ft

31.05 (200-yr)

33.98 (HTOL)
-4.95
-2.02 Meets Meets Meets
24001006.001A/SAC24R176178 Page 20 of 57 April 17, 2025 © 2025 Kleinfelder
Analysis
Station Range
Approximate
ULE Station
Constructed
Remediation
Reference Report Summary 2025 ULDC Summary
Modeled
Remediation Report Reference
Highest
Previously
Modeled WSE
Meets/Does Not Meet
2025 WSE
(ft)
Difference 2025
WSE – Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
Through
Seepage1
Steady -State
Landside
Stability Factor
of Safety (FOS)
Rapid Drawdown
Waterside Stability
FOS 2,3
Through
Seepage1
SteadyState
Landside
Stability
Rapid
Drawdown
Waterside
Stability
1235+00 Existing
Conditions
Existing
Conditions
2014 Sacramento River
ULE GER 37.6 (HTOL) Meets
Not Evaluated
Due to No Soft
Soils
Meets (1.10)
200-yr WSE (34.6 ft)
to 22.4 ft

30.78 (200-yr)

33.69 (HTOL)
-6.82
-3.91 Meets
Not
Evaluated
Meets
1244+50 7
SC Jet Grout
COW to EL -30
ft
SCB COW to EL
-30 ft
January 26, 2023, SGAM
SREL-4

35.6 (HTOL) Meets Meets (4.25 to

4.83)
Meets (2.05)
GDWSE (33.6 ft) to

11.6 ft

30.70 (200-yr)

33.60 (HTOL)
-4.90
-2.00 Meets Meets Meets
1249+50 SCB DMM COW
to EL -40 ft
SCB COW to EL
-43.6 ft
January 26, 2023, SGAM
SREL-4

35.6 (HTOL) Meets Meets (1.41)
Does Not Meet
(0.84), Accepted 8
GDWSE (33.6 ft) to

25.6 ft

30.66 (200-yr)

33.56 (HTOL)
-4.94
-2.04 Meets Meets Accepted
8 1260+50 SCB DMM COW
to EL -46 ft
SCB COW to EL
-46.3 ft
January 26, 2023, SGAM
SREL-4

35.5 (HTOL) Meets Meets (1.37)
Meets (2.31)
GDWSE (33.5 ft) to

11.5 ft

30.56 (200-yr)

33.45 (HTOL)
-4.94
-2.05 Meets Meets Meets
1265+00 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

35.7 (HTOL) Meets Meets (1.48)
Meets (1.52)
200-yr WSE (32.7 ft)
to 24.7 ft

30.52 (200-yr)

33.41 (HTOL)
-5.18
-2.29 Meets Meets Meets
1266+00 Existing
Conditions
Existing
Conditions
2014 Sacramento River
ULE GER 37.3 (HTOL) Meets Meets (1.49)
Meets (1.52)
200-yr WSE (34.3 ft)
to 23.3 ft

30.52 (200-yr)

33.41 (HTOL)
-6.78
-3.89 Meets Meets Meets
1418+00 to
1534+40
1425+00 SCB DMM COW
to EL -74 ft
SCB COW to EL
-69 ft
September 10, 2021,
SGAM SREL-3

33.9 (HTOL) Meets Meets (1.65)
Meets (1.51)
GDWSE (31.9 ft) to

9.9 ft

29.13 (200-yr)

31.88 (HTOL)
-4.77
-2.02 Meets Meets Meets
1439+02 SB COW to EL
-62 ft
SCB COW to EL
-62.5 ft
September 10, 2021,
SGAM SREL-3

33.8 (HTOL) Meets Meets (2.56)
Meets (1.71)
GDWSE (31.8 ft) to

9.8 ft

29.03 (200-yr)

31.77 (HTOL)
-4.77
-2.03 Meets Meets Meets
1449+00 SB COW to EL
-47 ft
SCB COW to EL
-44.7 ft
September 10, 2021,
SGAM SREL-3

33.8 (HTOL) Meets Meets (1.63)
Meets (2.61)
GDWSE (31.8 ft) to

9.8 ft

29.01 (200-yr)

31.75 (HTOL)
-4.79
-2.05 Meets Meets Meets
1471+30 SB COW to EL
-45 ft
SCB COW to EL
-45 ft
September 10, 2021,
SGAM SREL-3 – from
SRELIP (GEI/HDR, 2016)

33.5 (HTOL) Meets Meets (1.97)
Meets (1.20)
GDWSE (31.49 ft) to

23.49 ft

28.77 (200-yr)

31.49 (HTOL)
-4.73
-2.01 Meets Meets Meets
1485+50 SB COW to EL
-51 ft
SCB COW to EL
-51 ft
September 10, 2021,
SGAM SREL-3

33.3 (HTOL) Meets Meets (1.62)
Meets (1.42)
GDWSE (31.3 ft) to

23.3 ft

28.55 (200-yr)

31.24 (HTOL)
-4.75
-2.06 Meets Meets Meets
24001006.001A/SAC24R176178 Page 21 of 57 April 17, 2025 © 2025 Kleinfelder
Analysis
Station Range
Approximate
ULE Station
Constructed
Remediation
Reference Report Summary 2025 ULDC Summary
Modeled
Remediation Report Reference
Highest
Previously
Modeled WSE
Meets/Does Not Meet
2025 WSE
(ft)
Difference 2025
WSE – Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
Through
Seepage1
Steady -State
Landside
Stability Factor
of Safety (FOS)
Rapid Drawdown
Waterside Stability
FOS 2,3
Through
Seepage1
SteadyState
Landside
Stability
Rapid
Drawdown
Waterside
Stability
1497+40 SCCB COW to EL
-51 ft
SCB COW to EL
-50.7 ft
September 10, 2021,
SGAM SREL-3

33.3 (HTOL) Meets Meets (1.39)
Meets (1.34)
GDWSE (31.3 ft) to

23.3 ft

28.56 (200-yr)

31.26 (HTOL)
-4.74
-2.04 Meets Meets Meets
1511+00 SB COW to EL
-51 ft
SCB COW to EL
-50 ft
September 10, 2021,
SGAM SREL-3 – from
SRELIP (GEI/HDR, 2016)

33.3 (HTOL) Meets Meets (1.62)
Meets (2.00)
200-yr WSE (31.28
ft) to 9.28 ft

28.50 (200-yr)

31.20 (HTOL)
-4.80
-2.10 Meets Meets Meets
1524+04 SCB DMM COW
to EL -110 ft
SCB COW to EL
-109.6 ft
September 10, 2021,
SGAM SREL-3

33.2 (HTOL) Meets Meets (1.60)
Meets (1.54)
GDWSE (31.2 ft) to

9.2 ft

28.42 (200-yr)

31.12 (HTOL)
-4.78
-2.08 Meets Meets Meets
1532+50
(Sump 132)
SB Jet Grout
COW to EL -105
ft
SCB COW to EL
-103.8 ft
January 26, 2023, SGAM
SREL-4 33.2 (HTOL) Meets Meets (2.12)
Meets (1.51)
GDWSE (31.2 ft) to

9.5 ft

28.36 (200-yr)

31.05 (HTOL)
-4.84
-2.15 Meets Meets Meets
1640+00 to
1770+00
1648+00 Existing
Conditions
Existing
Conditions
January 26, 2023, SGAM
SREL-4

32.2 (HTOL) Meets Meets (1.62)
Meets (1.22)
EWSE (29.7 ft) to

7.7 ft

27.55 (200-yr)

30.16 (HTOL)
-4.65
-2.04 Meets Meets Meets
1650+00 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

31.9 (HTOL) Meets Meets (1.41)
Meets (1.25)
200-yr WSE (29.0 ft)
to 21.0 ft

27.54 (200-yr)

30.15 (HTOL)
-4.36
-1.75 Meets Meets Meets
1653+00 Existing
Conditions
Existing
Conditions
January 26, 2023, SGAM
SREL-4

32.2 (HTOL) Meets Meets (1.46)
Meets (1.25)
EWSE (29.6 ft) to

21.6 ft

27.52 (200-yr)

30.12 (HTOL)
-4.68
-2.08 Meets Meets Meets
1689+50 Existing
Conditions
Existing
Conditions
January 26, 2023, SGAM
SREL-4

31.6 (HTOL) Meets Meets (1.81)
Meets (1.23)
EWSE (29.2 ft) to

7.2 ft

27.13 (200-yr)

29.67 (HTOL)
-4.47
-1.93 Meets Meets Meets
1689+50
Drained
Stability Berm
STA 1689+07 to
1690+00
Inset Drained
Stability Berm
January 26, 2023, SGAM
SREL-4

31.6 (HTOL) Meets Meets (2.35)
Meets (1.23)
GDWSE (29.7 ft) to

7.7 ft

27.13 (200-yr)

29.67 (HTOL)
-4.47
-1.93 Meets Meets Meets
1691+00 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

31.49 (HTOL) Meets Meets (1.80)
Meets (1.30)
200-yr WSE (28.49
ft) to 20.49 ft

27.12 (200-yr)

29.66 (HTOL)
-4.37
-1.83 Meets Meets Meets
1720+00
Existing
Condition +
Curb Wall
Existing
Conditions
January 26, 2023, SGAM
SREL-4

31.5 (HTOL) Meets Meets (1.73)
Meets (1.73)
EWSE (29.1 ft) to

7.1 ft

27.01 (200-yr)

29.55 (HTOL)
-4.49
-1.95 Meets Meets Meets
24001006.001A/SAC24R176178 Page 22 of 57 April 17, 2025 © 2025 Kleinfelder
Analysis
Station Range
Approximate
ULE Station
Constructed
Remediation
Reference Report Summary 2025 ULDC Summary
Modeled
Remediation Report Reference
Highest
Previously
Modeled WSE
Meets/Does Not Meet
2025 WSE
(ft)
Difference 2025
WSE – Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
Through
Seepage1
Steady -State
Landside
Stability Factor
of Safety (FOS)
Rapid Drawdown
Waterside Stability
FOS 2,3
Through
Seepage1
SteadyState
Landside
Stability
Rapid
Drawdown
Waterside
Stability
1724+70 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

31.1 (HTOL) Meets Meets (1.70)
Meets (1.96)
200-yr WSE (28.3 ft)
to 20.3 ft

26.98 (200-yr)

29.52 (HTOL)
-4.12
-1.58 Meets Meets Meets
1729+60 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

31.1 (HTOL) Meets Meets (2.79) Not Evaluated 26.97 (200-yr)

29.50 (HTOL)
-4.13
-1.60 Meets Meets
Not
Evaluated
1730+00
Existing
Condition +
Curb Wall
Existing
Conditions
January 26, 2023, SGAM
SREL-4

31.5 (HTOL) Meets Meets (1.39)
Meets (1.61)
EWSE (29.0 ft) to

7.0 ft

26.97 (200-yr)

29.50 (HTOL)
-4.53
-2.00 Meets Meets Meets
1735+00
Existing
Condition +
Curb Wall
Existing
Conditions
January 26, 2023, SGAM
SREL-4

31.4 (HTOL) Meets Meets (1.49 to

1.83)
Meets (1.87)
EWSE (28.9 ft) to

6.9 ft

26.91 (200-yr)

29.44 (HTOL)
-4.49
-1.96 Meets Meets Meets
1735+50 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

31.0 (HTOL) Meets Meets (1.37) Not Evaluated 26.91 (200-yr)

29.43 (HTOL)
-4.09
-1.57 Meets Meets
Not
Evaluated
1751+25 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

30.8 (HTOL) Meets Meets (1.61)
Meets (1.67)
200-yr WSE (28.0 ft)
to 20.0 ft

26.76 (200-yr)

29.26 (HTOL)
-4.04
-1.54 Meets Meets Meets
1760+00 Existing
Conditions
Existing
Conditions
April 29, 2016, ULDC
Geotechnical Results
Summary, SREL

30.8 (HTOL) Meets Meets (1.62)
Meets (1.58)
200-yr WSE (28.0 ft)
to 20.0 ft

26.71 (200-yr)

29.21 (HTOL)
-4.09
-1.59 Meets Meets Meets
1 – For through seepage, reaches where the phreatic seepage surface for the 200-year WSE exited on a levee slope (i.e., through seepage) that is composed of erodible material (sands and non-plastic silts and silty sands) and were generally considered to not meet criteria. 2 – The WSEs listed below the Rapid Drawdown waterside slope FOS show the WSE drop analyzed for Rapid Drawdown waterside stability analysis. The highest WSE is typically the 200-yr WSE, GDWSE (Geotechnical Design Water Surface Elevation), or EWSE (Evaluation Water Surface Elevation) as defined in the referenced report. Rapid Drawdown analysis was not performed on all analysis sections in the referenced reports. Rapid drawdown analysis was only performed for critical sections. Acceptance was based on review of the sections and concurrence that critical sections were analyzed and met criteria. 3 – Rapid Drawdown results for the 2014 Sacramento River ULE GER correspond to “the SLOPE/W analysis output at the 200-year WSE for the deeper slip surface into the levee crown with the critical factor of safety” (URS, 2014). 4 – The 2025 HTOL WSE (36.32 feet) is below the 2014 ULE 200-year WSE (36.4 feet). Because through seepage conditions were met for the ULE 200-year WSE, the 2025 HTOL WSE also meets criteria. 5 – Although the Rapid Drawdown conditions do not meet criteria, the SGAM notes that the USACE Erosion Team determined that since the levee crown elevation approximately matches the landside ground surface, a breach at Station 1035+00 would likely not result in extensive flooding of the area, and the area would not be remediated for rapid drawdown. Additionally, the nearby analyses at Station 1011+00 and 1029+50 do not include excess material but meet Rapid Drawdown criteria. 6 – Rapid Drawdown results are below Factor of Safety 1.2 but are acceptable in the SGAM because they do not enter the area 20 feet from the landside hinge. 7 – The as-built jet grout wall was constructed between Stations 1244+73 and 1249+40; Station 1244+50 was the model cross section. 8 – The levee reach containing Station 1249+50 was remediated by the Sacramento River Bank Protection Program in 2022. Rapid Drawdown is considered meeting criteria due to the remediations. 9 – Analysis assumes Caltrans dewatering system, which is not part of the recognized flood system, for Interstate 5 (I-5) depressed section is functioning. See discussion of I-5 depressed section in Section 2.3. 24001006.001A/SAC24R176178 Page 23 of 57 April 17, 2025 © 2025 Kleinfelder
Based on this review the following conclusions can be made:
• Analysis cross sections model slope stability along SREL at critical locations. • The 2025 200-year and HTOL WSEs are lower than the WSE modeled in the existing analyses. • The modeled improvements at the analysis cross section were the same or more conservative than the constructed improvements and met criteria at the analyzed locations.

2.2.1 Conclusion
Based on the above review, it is Kleinfelder’s opinion that SREL-A through SREL-E segments meet the requirements of ULDC 7.4 Slope Stability for Intermittently Loaded Levees through Exception due to the reliance on the Caltrans dewatering system at Station 1072+00. It is understood this exception will be reviewed every 5 years.

2.3 ULDC SECTION 7.5 UNDERSEEPAGE FOR INTERMITTENTLY LOADED LEVEES This section contains a summary of the review of the existing reports and analyses performed for SREL-A through SREL-E segments as it applies to ULDC Section 7.5 Underseepage for Intermittently Loaded Levees. As discussed in Section 2.2, the SREL levees are intermittently loaded levees. The general requirements of ULDC Section 7.5 Underseepage for Intermittently Loaded Levees are outlined below.

ULDC 7.5 requires seepage analysis performed for the design water surface elevation (DWSE) and the hydraulic top of levee (HTOL) WSE. Exit gradients measured at the landside levee toe, seepage berm toe, ditches, canals, depressions, or areas of thin blanket. The allowable maximum exit gradient is summarized in the table below.

Seepage Analysis Location Allowable Maximum Exit
Gradient
Steady-State DWSE
Landside Levee Toe 0.51
Ditches, canals, depressions,
berms 0.5-0.82
Steady-State HTOL WSE
Landside Levee Toe 0.6
Ditches, canals, depressions,
berms 0.6-0.92

1. The allowable underseepage exit gradient through the combined seepage berm/blanket layer between the levee toe and the seepage berm toe for a water surface set at the DWSE is determined by interpolation, using 0.5 at the levee toe and 0.8 at the seepage berm toe.

2. Maximum allowable exit gradient at the landside levee toe is 0.5 and up to 0.8 at 150 feet from the levee toe, using linear interpolation for distances in between. ULDC does allow for higher exit gradients at the seepage berm toe provided sound engineer judgement, and additional analysis. 24001006.001A/SAC24R176178 Page 24 of 57 April 17, 2025 © 2025 Kleinfelder
For the HTOL, “In general if the berm is less than 100-ft wide, the maximum exit gradient may increase by up to 20 percent of the DWSE maximum exit gradient.“ ULDC 7.5 provides criteria for blanket layer soils with saturated unit weights of 112 pcf or less. SREL stratigraphy blanket layers did not require this analysis because saturated unit weights were greater than the minimum specified.

Detailed discussions of the seepage analyses previously performed are discussed in the reports listed in Section 1.5 and included in the reference list. These analyses results were compared with the 2025 200- year and HTOL WSEs (MBK, 2025). Since the previously performed analyses were analyzed with a WSE above the 2025 200-year and HTOL WSEs and met seepage criteria, the analyses are considered to meet criteria for the 2025 WSEs. Table 2.7 contains the previously performed analysis results with the previously used design WSEs and the 2025 WSEs.
24001006.001A/SAC24R176178 Page 25 of 57 April 17, 2025 © 2025 Kleinfelder
Table 2.7
Seepage Analyses Comparison Summary
Analysis
Station
Range
Approximate
ULE Station
Constructed
Remediation
Reference Report Summary 2025 ULDC Summary
Modeled Remediation Report Reference
Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
2025 WSE
(ft)
Difference 2025
WSE – Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
Underseepage Underseepage
1000+00 to
1080+00
1005+00 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

38.2 (HTOL) Meets (0.22) 33.36 (200-yr)

36.36 (HTOL)
-4.84
-1.84
Meets
1011+00 Existing Conditions Existing Conditions 2014 Sacramento River ULE GER 39.4 (HTOL) Meets (0.10) 33.30 (200-yr)36.30 (HTOL) -6.10
-3.10
Meets
1029+50 Geometry Correction Geometry Correction
January 26, 2023,
Supplemental Geotechnical
Analysis Memorandum (SGAM)
SREL-4

38.1 (HTOL) Meets (0.19) 33.04 (200-yr)

36.04 (HTOL)
-5.06
-2.06
Meets
1035+00 Geometry Correction Geometry Correction January 26, 2023, SGAM SREL-4 38.0 (HTOL) Meets (0.14) 32.95 (200-yr)

35.95 (HTOL)
-5.05
-2.05
Meets
1072+00 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

37.7 (HTOL) Meets (0.00)1

32.34 (200-yr)

35.34 (HTOL)
-5.36
-2.36
Meets
1 1150+00 to
1185+00
1160+00 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

36.5 (HTOL) Meets (0.53) 31.48 (200-yr)

34.43 (HTOL)
-5.02
-2.07
Meets
1172+00 Existing Conditions Existing Conditions (4
Sensitivities) January 26, 2023, SGAM SREL-4 36.2 (HTOL) Meets (0.22 to 0.40 LS Toe, 0.46
to 0.49 LS Low Spot, compilation
of sensitivity analyses)

31.37 (200-yr)

34.31 (HTOL)
-4.83
-1.89
Meets
1206+00 to
1285+75
1207+50 Existing Conditions Existing Conditions January 26, 2023, SGAM SREL-4 36.0 (HTOL) Meets (0.31 to 0.58) 31.05 (200-yr)

33.98 (HTOL)
-4.95
-2.02
Meets
1235+00 Existing Conditions Existing Conditions 2014 Sacramento River ULE GER 37.6 (HTOL) Meets (0.31) 30.78 (200-yr)33.69 (HTOL) -6.82
-3.91
Meets
1244+50 Jet Grout SCB COW to EL
-30 ft SCB COW to EL -30 ft January 26, 2023, SGAM SREL-4 35.6 (HTOL) Meets (0.33) 30.70 (200-yr)33.60 (HTOL) -4.90
-2.00
Meets
1249+50 DMM SCB COW to EL -40
ft SCB COW to EL -43.6 ft January 26, 2023, SGAM SREL-4 35.6 (HTOL) Meets (0.50) 30.66 (200-yr)33.56 (HTOL) -4.94
-2.04
Meets
1260+50 DMM SCB COW to EL -46
ft SCB COW to EL -46.3 ft January 26, 2023, SGAM SREL-4 35.5 (HTOL) Meets (0.29) 30.56 (200-yr)33.45 (HTOL) -4.94
-2.05
Meets
1265+00 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

35.7 (HTOL) Meets (0.39 CL, 0.28 CL & ML) 30.52 (200-yr)

33.41 (HTOL)
-5.18
-2.29
Meets
1266+00 Existing Conditions Existing Conditions 2014 Sacramento River ULE GER 37.3 (HTOL) Meets (0.28) 30.52 (200-yr)33.41 (HTOL) -6.78
-3.89
Meets
1418+00 to
1534+40
1425+00 DMM SCB COW to EL -74
ft SCB COW to EL -69 ft September 10, 2021, SGAM SREL-3

33.9 (HTOL) Meets (<0.01) 29.13 (200-yr)

31.88 (HTOL)
-4.77
-2.02
Meets
1439+02 SB COW to EL -62 ft SCB COW to EL -62.5 ft September 10, 2021, SGAM SREL-3

33.8 (HTOL) Meets (<0.01) 29.03 (200-yr)

31.77 (HTOL)
-4.77
-2.03
Meets
1449+00 SB COW to EL -47 ft SCB COW to EL -44.7 ft September 10, 2021, SGAM SREL-3

33.8 (HTOL) Meets (<0.01) 29.01 (200-yr)

31.75 (HTOL)
-4.79
-2.05
Meets
24001006.001A/SAC24R176178 Page 26 of 57 April 17, 2025 © 2025 Kleinfelder
Analysis
Station
Range
Approximate
ULE Station
Constructed
Remediation
Reference Report Summary 2025 ULDC Summary
Modeled Remediation Report Reference
Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
2025 WSE
(ft)
Difference 2025
WSE – Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
Underseepage Underseepage
1471+30 SB COW to EL -45 ft SCB COW to EL -45 ft
September 10, 2021, SGAM
SREL-3 – from SRELIP (GEI/HDR,
2016)

33.5 (HTOL) Meets (<0.01) 28.77 (200-yr)

31.49 (HTOL)
-4.73
-2.01
Meets
1485+50 SB COW to EL -51 ft SCB COW to EL -51 ft September 10, 2021, SGAM SREL-3

33.3 (HTOL) Meets, 0.33 to 0.36 (over
composite blanket)

28.55 (200-yr)

31.24 (HTOL)
-4.75
-2.06
Meets
1497+40 SCCB COW to EL -51 ft SCB COW to EL -50.7 ft September 10, 2021, SGAM SREL-3

33.3 (HTOL) Meets (0.29 to 0.32) 28.56 (200-yr)

31.26 (HTOL)
-4.74
-2.04
Meets
1511+00 SB COW to EL -51 ft SCB COW to EL -50 ft
September 10, 2021, SGAM
SREL-3 – from SRELIP (GEI/HDR,
2016)

33.3 (HTOL) Meets, 0.39 to 0.43 (over
composite blanket)

28.50 (200-yr)

31.20 (HTOL)
-4.80
-2.10
Meets
1524+04 DMM SCB COW to EL -
110 ft SCB COW to EL -109.6 ft September 10, 2021, SGAM SREL-3

33.2 (HTOL) Meets (<0.01) 28.42 (200-yr)

31.12 (HTOL)
-4.78
-2.08
Meets
1532+50
(Sump 132)
COW to EL -105 ft using
Jet Grout Method SCB COW to EL -103.8 ft January 26, 2023, SGAM SREL-4 Reach 23, STA 1532+50 33.2 (HTOL) Meets (0.07) 28.36 (200-yr)31.05 (HTOL) -4.84
-2.15
Meets
1640+00 to
1770+00
1648+00 Existing Conditions Existing Conditions January 26, 2023, SGAM SREL-4 32.2 (HTOL) Meets, 0.35 to 0.50 27.55 (200-yr)

30.16 (HTOL)
-4.65
-2.04
Meets
1650+00 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

31.9 (HTOL) Meets (0.49 LS toe, 0.67 LS Low
Point)

27.54 (200-yr)

30.15 (HTOL)
-4.36
-1.75
Meets
1653+00 Existing Conditions Existing Conditions January 26, 2023, SGAM SREL-4 32.2 (HTOL) Meets (0.25) 27.52 (200-yr)

30.12 (HTOL)
-4.68
-2.08
Meets
1689+50 Existing Conditions Existing Conditions January 26, 2023, SGAM SREL-4 31.6 (HTOL) Meets (0.12) 27.13 (200-yr)

29.67 (HTOL)
-4.47
-1.93
Meets
1689+50 Drained Stability Berm
STA 1689+07 to 1690+00
Inset Drained Stability
Berm January 26, 2023, SGAM SREL-4 31.6 (HTOL) Meets (0.09) 27.13 (200-yr)29.67 (HTOL) -4.47
-1.93
Meets
1691+00 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

31.49 (HTOL) Meets (0.10 to 0.26) 27.12 (200-yr)

29.66 (HTOL)
-4.37
-1.83
Meets
1720+00 Existing Conditions Existing Conditions January 26, 2023, SGAM SREL-4 31.5 (HTOL) Meets (0.45 to 0.56) 27.01 (200-yr)

29.55 (HTOL)
-4.49
-1.95
Meets
1724+70 Existing Condition + Curb
Wall Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

31.1 (HTOL) Meets (0.55) 26.98 (200-yr)

29.52 (HTOL)
-4.12
-1.58
Meets
1729+60 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

31.1 (HTOL) Meets (0.26) 26.97 (200-yr)

29.50 (HTOL)
-4.13
-1.60
Meets
1730+00 Existing Condition + Curb
Wall Existing Conditions January 26, 2023, SGAM SREL-4 31.5 (HTOL) Meets (0.11 to 0.32) 26.97 (200-yr)29.50 (HTOL) -4.53
-2.00
Meets
1735+00 Existing Condition + Curb
Wall Existing Conditions January 26, 2023, SGAM SREL-4 31.4 (HTOL) Meets (0.42 to 0.60) 26.91 (200-yr)29.44 (HTOL) -4.49
-1.96
Meets
1735+50 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

31.0 (HTOL) Meets (0.51) 26.91 (200-yr)

29.43 (HTOL)
-4.09
-1.57
Meets
1751+25 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

30.8 (HTOL) Meets (0.27) 26.76 (200-yr)

29.26 (HTOL)
-4.04
-1.54
Meets
24001006.001A/SAC24R176178 Page 27 of 57 April 17, 2025 © 2025 Kleinfelder
Analysis
Station
Range
Approximate
ULE Station
Constructed
Remediation
Reference Report Summary 2025 ULDC Summary
Modeled Remediation Report Reference
Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
2025 WSE
(ft)
Difference 2025
WSE – Highest
Previously
Modeled WSE
(ft)
Meets/Does Not Meet
Underseepage Underseepage
1760+00 Existing Conditions Existing Conditions
April 29, 2016, ULDC
Geotechnical Results Summary,
SREL

30.8 (HTOL) Meets (0.33) 26.71 (200-yr)

29.21 (HTOL)
-4.09
-1.59
Meets
1-Analysis assumes Caltrans dewatering system for Interstate 5 depressed section is functioning. This system is controlled and operated by Caltrans and is not part of the recognized flood system. See discussion in Section 2.3.1. 24001006.001A/SAC24R176178 Page 28 of 57 April 17, 2025 © 2025 Kleinfelder
Based on this review the following conclusions can be made:
• Analysis cross sections model underseepage along the subject portions of SREL at critical locations.
• The 2025 200-year and HTOL WSEs are lower than the WSE modeled in the existing analyses. • The modeled improvements were the same or more conservative than the constructed improvement and met criteria at the analyzed locations.

2.3.1 Interstate 5 Depressed Section
This section of highway was originally constructed by Caltrans in the early 1970s and is referred to as the Interstate 5 Depressed Section (Depressed Section). The deepest part of the roadway surface is at about Elevation 0. The bottom of the structure is referred to as the Riverfront Seal Slab (RSS) and was designed to resist buoyant uplift forces with a gravity section that is up to 12 feet thick and a tension section with concrete tension piles where greater uplift resistance was needed. Structure retaining walls were constructed on both sides of the roadway and were designed with gravel drains extending from the ground surface to Elevation 27 NAVD88 with waterproofing below that level, which extended beneath the RSS. Due to concerns about the Depressed Section performance during the 1986 flood event, dewatering wells were added between the Sacramento River and west retaining walls of the structure sporadically through 2008. In 2008, several sensors that monitor and record hydrostatic pressure beneath the RSS and monitoring wells with sensors that monitor groundwater levels were installed at the site during a major improvement project of the Depressed Section. An additional sensor was located within the Sacramento River and records changes in river elevation. Data is collected remotely by and maintained by Caltrans.

The seepage analysis at Station 1072+00 includes the Sacramento Promenade river wall and the Depressed Section including the dewatering system operated by Caltrans. In order for the analysis models to meet ULDC criteria for seepage and slope stability, the dewatering system must function. The river wall and Depressed Section retaining wall are approximately 110 feet apart. The dewatering system consists of pumped dewatering wells at 4 locations – N Street, P Street, Q Street, and Firehouse Alley. The N, P, and Q street locations include 2 wells, a primary well and a backup well, and Firehouse Alley is a single well. A diesel-powered backup generator at N Street is part of the system that functions if the wells lose electrical service. This system is discussed in detail in Appendix E of the ULDC Geotechnical Summary (Kleinfelder 2016).
24001006.001A/SAC24R176178 Page 29 of 57 April 17, 2025 © 2025 Kleinfelder
Recent discussions between USACE and Caltrans to jointly operate and maintain the system as part of the federal flood control system have been unsuccessful. Therefore, USACE is reassessing the area without the dewatering system to determine if additional remedial measures are needed for this location. A potential failure scenario would include the dewatering system not functioning as designed, which would cause excess hydrostatic pressure in the depressed roadway section and could result in either uplift and cracking of the I-5 seal slab or failure of the pile supported retaining walls on the west side of I-5. Breach would only occur if the Riverwalk Promenade river wall also failed. If water begins to seep into the depressed section, it would collect in the lowest portions (about Elevation 0) until it spills out the northern or southern end of the depressed section (estimated at Elevation 13 to 14 feet and roughly at Stations 1057+00 and 1095+003). However, this scenario only occurs if the dewatering system does not function as designed.

The seepage model for Station 1072+00 is considered to meet ULDC criteria through the exception that the Caltrans dewatering system that is not part of the flood protection system must be operating. This exception should be reviewed on a 5-year basis or as additional studies of the I-5 depressed section are performed.

2.3.2 Geotechnical Evaluation of Swimming Pools at or Near the Landside Toe Swimming pools built below the ground surface near the landside levee toe can locally reduce the thickness of the fine-grained blanket layer and create a potential point of weakness for underseepage.

Several pools exist at private residences within 100 feet of the landside toe in the Little Pocket and Pocket areas of Sacramento in Reaches C, D, and E. Therefore, a review of existing swimming pools was performed.

Swimming pools were previously addressed in the 2017 GEI SREL Improvement Project (SRELIP) Swimming Pool Screening Memorandum. As part of the SGAMs for SREL-3 (Kleinfelder, 2021) and SREL-4 (Kleinfelder, 2023), Kleinfelder reviewed the memorandum and agreed with its findings. The memo concluded that all swimming pools in the SRELIP study area meet ULDC underseepage criteria so long as the pools are kept full during the high-water season. The SGAMs note that swimming pools should be points of interest during levee patrols.
3 These are rough estimates only. A detailed study would be needed to assess the potential for the I-5 depressed section to hold water and the elevation that water escapes.
24001006.001A/SAC24R176178 Page 30 of 57 April 17, 2025 © 2025 Kleinfelder
The swimming pools within the study area for this ULDC required updated evaluations because recent remediations are expected to lower the average exit gradients at the pool locations. The review was performed as outlined below.

1. Using Google Earth, all swimming pools at or near the landside levee toe within the study area were located.

2. If identified, the distance of the swimming pool from the landside levee toe was measured.

3. The nearest seepage analysis that models the constructed remediations from Section 2.3, Table

2.7 was then reviewed. After adjusting the analyzed WSE for the 2025 200-yr WSE or 2025 HTOL (contained in Appendix A), the seepage analysis was used to calculate the exit gradients across the blanket layer at the bottom of the pool for full pool and empty pool scenarios:
a. Full Pool: The average gradient is measured across the blanket layer at the bottom of the pool (assumed depth of 7 feet) with the total head assumed to be equal to the ground surface elevation adjacent to the pool. The gradient measurement does not include the presence of the pool lining as part of the estimation. b. Empty Pool: The average gradient is measured across the blanket layer at the bottom of the pool (assumed depth of 7 feet) with the total head assumed to be equal to the ground surface elevation at the bottom of the pool.

4. The allowable gradient was based on the measured distance from the landside levee toe; 0.50 at toe, 0.80 at 150 feet away from toe. This is based on the California Code of Regulations Title 23 and USACE Geotechnical Levee Practice Setback Guidance (May 2022).

5. This procedure is consistent with the procedure used in the GEI SRELIP memorandum (GEI, 2017).

Fifty-three pools were identified in the study area. The results for evaluating exit gradients with the 2025 200-yr WSE are listed in Table B-1 of Appendix B; the results for evaluating exit gradient with the 2025 HTOL are listed in Table B-2 of Appendix B. All pools met exit gradient criteria when full; however, 17 pools for 200-year WSE and 24 pools for HTOL WSE did not meet allowable exit gradient requirements when empty and are listed in Table 2.8.

Table 2.8
Swimming Pools Geotechnical Underseepage Evaluation
24001006.001A/SAC24R176178 Page 31 of 57 April 17, 2025 © 2025 Kleinfelder
ULDC Analysis
Reach / Pool No.

Station at
Pool
Location
Distance from
Landside Levee
Toe (ft)
Allowable Exit
Gradient at Bottom
of Pool
Average Exit Gradient at Bottom of Pool
200-Year DWSE HTOL WSE
Gradient at
Pool Location
(Full Pool)
Gradient at
Pool Location
(Empty Pool)
Gradient at
Pool Location
(Full Pool)
Gradient at
Pool Location
(Empty Pool)
SREL-C / 1 1250+59 44 0.59 0.32 0.63 0.42 0.73
SREL-C / 2 1258+27 31 0.56 0.21 0.52 0.28 0.59
SREL-C / 3 1259+09 39 0.58 0.21 0.52 0.28 0.59
SREL-C / 4 1261+90 36 0.57 0.23 0.84 0.33 0.94
SREL-C / 5 1263+20 47 0.59 0.23 0.83 0.32 0.93
SREL-C / 6 1264+10 40 0.58 0.05 0.66 0.15 0.76
SREL-C / 7 1265+10 35 0.57 0.14 0.75 0.25 0.86
SREL-C / 8 1266+25 20 0.54 0.14 0.75 0.25 0.86
SREL-C / 9 1267+00 54 0.61 0.23 0.83 0.32 0.93
SREL-C / 10 1268+00 60 0.62 0.23 0.83 0.32 0.93
SREL-C / 11 1279+40 70 0.64 0.13 0.74 0.21 0.82
SREL-C / 12 1280+75 35 0.57 0.22 0.83 0.31 0.92
SREL-C / 13 1283+80 75 0.65 0.22 0.83 0.30 0.90
SREL-C / 14 1284+40 15 0.53 0.13 0.74 0.23 0.83
SREL-D / 23 1499+25 70 0.64 0.23 0.58 0.37 0.71
SREL-D / 24 1499+60 91 0.68 0.22 0.57 0.37 0.71
SREL-D / 25 1501+46 71 0.64 0.23 0.58 0.37 0.71
SREL-D / 27 1507+38 23 0.55 0.28 0.60 0.40 0.72
SREL-D / 28 1512+20 48 0.60 0.30 0.63 0.35 0.69
24001006.001A/SAC24R176178 Page 32 of 57 April 17, 2025 © 2025 Kleinfelder
ULDC Analysis
Reach / Pool No.

2.3.3 Conclusion
Based on the above review, it is Kleinfelder’s opinion SREL-A through SREL-E segments meet the requirements of ULDC 7.5 Underseepage for Intermittently Loaded Levees through Exception due to the reliance on the Caltrans dewatering system at Station 1072+00. This exception should be reviewed on a 5-year basis or as additional studies of the I-5 depressed section are performed.

2.4 ULDC SECTION 7.7 SEISMIC VULNERABILITY
This section contains a summary of the review of the existing reports and analyses performed for SREL and as it applies to ULDC Section 7.7 - Seismic Vulnerability – specifically for Intermittently Loaded Levees (Section 7.7.1).

The objective of the seismic vulnerability evaluation was to develop information to characterize the potential vulnerability of levee segments during the postulated 200-year return period seismic event.

This information can then be used as a basis to classify the levees in terms of their ability to provide post-seismic flood protection in accordance with ULDC. In accordance with the ULDC, post-seismic flood 24001006.001A/SAC24R176178 Page 33 of 57 April 17, 2025 © 2025 Kleinfelder
protection requires maintaining a levee crown sufficient for protection against the 10-year flood with 3 feet of freeboard. For intermittently loaded levees (or floodwalls), the ULDC states the following requirement:
“If seismic damage from 200-year-return-period ground motions is expected after the urban level of flood protection is achieved, a post-earthquake remediation plan is required as part of a flood safety plan that is developed in coordination with pertinent local, State, and federal agencies.” Kleinfelder has been tasked by SAFCA with evaluating the seismic vulnerability of the SAFCA Sacramento area levees located in Sacramento and Sutter Counties, California in support of ULDC levee studies. The seismic vulnerability study performed by Kleinfelder is separate from this report and includes the entire American River South Levee System. As a part of this seismic vulnerability study, Kleinfelder prepared a Seismic Performance Summary Report (SPSR) that addresses the seismic vulnerability of the American River South Levee System (Kleinfelder, 2025), which includes the subject portions of SREL. This SPSR is included in Appendix C of this report. The subject study area levee reaches are located within the following seismic segments displayed on Appendix C Figure 1-1:
• SREL-A: SREL-1, SREL-2
• SREL-B: SREL-3, SREL-4
• SREL-C: SREL-4, SREL-5, SREL-6
• SREL-D: SREL-7, SREL-8
• SREL-E: SREL-8, SREL-9, SREL-10
Per the Urban Levee Evaluations guidance document (DWR, 2015), seismic vulnerability for intermittently loaded levees is based on a levee’s flood protection ability after a seismic event.

Estimations of vertical deformation and remaining freeboard as well as potential for embankment cracking and damage to internal structures (cutoff walls) were considered for classifying seismic vulnerability. In general, levees with over 1 foot of remaining freeboard (the levee height above the elevation equal to the 10-year WSE plus 3 feet) after a seismic event were classified Low Vulnerability, while levees with no remaining freeboard (i.e. bank collapse) after a seismic event were classified High Vulnerability. Refer to the SPSR in Appendix C for detailed descriptions of the classification for each seismic segment.
24001006.001A/SAC24R176178 Page 34 of 57 April 17, 2025 © 2025 Kleinfelder

2.4.1 Conclusion
Based upon the SPSR (Kleinfelder, 2025), the ULDC seismic vulnerability classifications for SREL-A through SREL-E segments are shown in Table 2.9.

Table 2.9
Seismic Vulnerability Classifications for American River South Levee System Levee Reach Station Start Station End 2025 Seismic
Vulnerability
SREL-A 1000+00 1080+00 High
SREL-B 1150+00 1185+00 High
SREL-C 1206+00 1285+75 High
SREL-D 1418+00 1534+40 High
SREL-E
1640+00 1671+00 High
1671+00 1707+50 Low
1707+50 1770+00 High
The SREL levees analyzed were classified as High Vulnerability except between Stations 1671+00 and 1707+50, which was classified as Low Vulnerability due to the lack of liquefiable soils beneath the levee.

As required by the ULDC, a Post-Earthquake Remediation Plan for the High Vulnerability levees was developed to address levee repair after damages resulting from a seismic event. It is Kleinfelder’s opinion that with the Post-Earthquake Remediation Plan for the ARSLS, the levee reaches outlined above meet the geotechnical aspects of Section 7.7 Seismic Vulnerability.

2.5 ULDC SECTION 7.8 LEVEE GEOMETRY
Kleinfelder evaluated the existing information for SREL-A through SREL-E segments with regards to ULDC Section 7.8 Levee Geometry from a geotechnical perspective, which is slope stability of the existing waterside and landside levee slopes. MBK is performing the full evaluation of Section 7.8, including Sections 7.8.1 Wide Levees and 7.8.2 Patrol Roads, Access Ramps, and Turnouts. The ULDC Section 7.8 Levee Geometry guidance is summarized as follows.

Minimum levee geometry criteria have previously been specified by various USACE and State guidance documents. The guidance for various minimum levee geometry and their references are as follows in Table 7-1 from the ULDC.
24001006.001A/SAC24R176178 Page 35 of 57 April 17, 2025 © 2025 Kleinfelder
“For new levees, or levees with extensive reconstruction, situated along major waterways, a minimum 20-foot-wide crown width and 3h:1v waterside and landside slopes (4h:1v waterside slope for bypass levees) is required. Exceptions may be allowed for reconstruction of existing levees where the authorized geometry provides for a steeper slope or narrower crown, the levee has performed well, and it meets stability and seepage criteria. These geometry requirements represent minimum requirements, and wider levee crowns and/or flatter slopes may be necessary in some areas, depending upon geologic and geotechnical considerations. At the same time, however, minimum requirements should be associated with generally uniform, levee materials and homogeneous embankments. Steeper slopes may be allowed in certain circumstances where there is limited space available, and where levees are demonstrated to meet minimum seepage and stability criteria. Steeper waterside levee slopes may be acceptable where stability criteria are met and either slope protection is provided, or it is determined that wavewash erosion for a water surface at or below the DWSE could not result in breaching of the levee. For example, levees with slopes steeper than new minimum requirements may be acceptable with elements such as central clay cores, seepage cutoff walls, landside filters or drains, or soil reinforcement that substantially decrease seepage hazards and increase slope stability.

The levee prism should be considered to continue underground based on projection of the aboveground levee slopes. The projected levee slopes are useful for evaluating erosion, excavations, and encroachments near the levee.”

2.5.1 Geotechnical Review of Levee Geometry
Psomas performed surveys in December 2024 at select locations along SREL and prepared topographic levee cross sections. The selected cross sections that Psomas surveyed included the analytical cross 24001006.001A/SAC24R176178 Page 36 of 57 April 17, 2025 © 2025 Kleinfelder
section locations discussed in Sections 2.2 Slope Stability and 2.3 Underseepage except for cross sections located within the extents of SREL Contracts 3 and 4 that were recently rebuilt. Kleinfelder reviewed the Psomas cross sections with the analytical cross section geometry to confirm the geometry was generally consistent. Kleinfelder performed a site visit to the SREL analysis reaches and no significant changes to the levee geometry (slope failures, erosion, etc.,) from the previous evaluations were noted.

MBK projected the ULDC project levee prism of 2H:1V landside slope, 3H:1V waterside slope, and a 20- foot crown width onto the Psomas levee survey cross sections. The figures of the levee geometry analysis are included in Appendix D.

Levee geometry from 2014 and 2024 surveys are summarized in Table 2.10.

Table 2.10
SREL Levee Crown and Landside Toe Reference Summary
ARSLS
Reach
Topography
Feature
Elevation
Range
(NAVD88, ft)
Source
SREL-A
Crown
30 1to 43 2
URS, 2014. “Geotechnical Evaluation Report, Sacramento River Study Area.” Sacramento River Plan and Profile Plates 3 through 4. 38 to 44 3
MBK Engineers, 2024. “American River South Levee System: Levee Geometry Analysis (ULDC).” Sheets 14 through 17.

Landside Toe
30 to 40 2 URS, 2014. Plates 3 through 4.
30 to 42 3 MBK Engineers, 2024. Sheets 14 through 17.

SREL-B
Crown
42 to 43 2 URS, 2014. Plate 6.
42 3 MBK Engineers, 2024. Sheet 20.

Landside Toe
21 to 30 2 URS, 2014. Plate 6.

N/A 4 MBK Engineers, 2024. Sheet 20.
24001006.001A/SAC24R176178 Page 37 of 57 April 17, 2025 © 2025 Kleinfelder
ARSLS
Reach
Topography
Feature
Elevation
Range
(NAVD88, ft)
Source
SREL-C
Crown
38 to 45 2 URS, 2014. Plates 7 through 8
39 to 42 3 MBK Engineers, 2024. Sheets 21 through 23.

Landside Toe
17 to 42 2 URS, 2014. Plates 7 through 8
20 to 40 3 MBK Engineers, 2024. Sheets 21 through 23.

SREL-D
Crown
33 to 36 2 URS, 2014. Plates 11 through 13
34 to 36 3 MBK Engineers, 2024. Sheets 26 through 29.

Landside Toe
17 to 28 2 URS, 2014. Plates 11 through 13
17 to 26 3 MBK Engineers, 2024. Sheets 26 through 29.

SREL-E
Crown
30 to 35 2 URS, 2014. Plates 15 through 18.
31 to 33 3 MBK Engineers, 2024. Sheets 31 through 33.

Landside Toe
15 to 30 2,5 URS, 2014. Plates 15 through 18.
17 to 22 3 MBK Engineers, 2024. Sheets 31 through 33.

1. Plan and profile crown elevation is generally at or above Elevation 38 but is around Elevation 30 from Station 1047+00 to 1057+00 (Old Sacramento high ground); no MBK cross sections were taken within this range.

2. Elevations estimated from plan and profile levee crown and landside toe lines.

3. Elevation range based on survey data performed by Psomas in 2024 on select SREL cross section locations Stations 1005+10, 1009+10, 1010+90, 1012+80, 1014+90, 1021+70, 1026+40, 1027+90, 1154+80, 1177+10, 1210+00, 1226+70, 1254+40, 1276+50, 1420+70, 1446+00, 1455+80, 1479+20, 1493+70, 1515+60, 1530+60, 1653+30, 1684+60, 1715+60, 1750+30, and 1770+00.

4. Landside toe is not shown on the MBK cross sections located within SREL-B.

5. Plan and profile landside toe elevation is generally at or above Elevation 20 but is around Elevation 30 from Station 1660+00 and 1673+00 (Freeport Water Intake Facility); no MBK cross sections were taken within this range.

The projected ULDC levee prism is generally shown within the existing surveyed levee prism. There are some locations where the waterside or landside levee slopes are steeper than the ULDC levee prism.

Stations 1021+70, 1026+40, and 1027+90 are within an area of high ground. The stability analyses described in Section 2.2 met the ULDC geotechnical criteria for intermittently-loaded levees at critical cross section locations and at higher WSEs than the 2025 WSEs. It should be noted that the waterside stability analysis does not include riverbank stability.

Based upon the above data, Kleinfelder makes the following conclusions:
• Locations where the projected ULDC levee prism does not fit within the existing Psomas surveyed levee prism meet for slope stability.
24001006.001A/SAC24R176178 Page 38 of 57 April 17, 2025 © 2025 Kleinfelder

2.5.2 Conclusion
Based on the information provided above it is Kleinfelder’s opinion that the SREL levee geometry meets the geotechnical aspects (slope stability of the existing waterside and landside levee slopes) of ULDC 7.8 Geometry.

2.6 ULDC SECTION 7.9 INTERFACES AND TRANSITIONS
This section contains a summary of the review of existing information for the subject portions of SREL with regards to ULDC Section 7.9 Interfaces and Transitions which is defined as follows:

The civil engineer must consider, evaluate, and explicitly design for interfaces and transitions between different types of levee sections and features along a levee system. Appropriate overlaps, transitions, and connections between features must be evaluated and designed to ensure that the levee system functions holistically, such that no levee reach is more susceptible to problems than an adjacent reach due to gaps in features, loading/demand concentrations, or other three-dimensional effects. Such interfaces, transitions, and connections commonly occur at the ends of seepage berms, seepage cutoff walls, revetments, and floodwalls.

Due to the high number of interfaces and transitions within the subject portions of SREL, they are organized into separate tables depending on feature type. Transitions of levee improvements including seepage cutoff walls are discussed in Section 2.6.1 (Table 2.11), encroachments and interfaces through the levee are discussed in Section 2.6.2 (Table 2.12), the transition from ARSL to SREL is discussed in Section 2.6.3, and the transition from SREL to Beach Lake North Levee (BLNL) is discussed in Section

2.6.4. 2.6.1 Levee Improvement Transitions
Levee improvements were constructed between 1990 and 2024 and extend throughout the subject portions of the SREL study area. The levee improvements were constructed in response to the 1986 and 1997 floods and seepage and boils observed near the levee landside toe, particularly in the Little Pocket and Pocket areas between Stations 1245+00 and 1660+00 (Kleinfelder, 2022). Transitions where different types of seepage cutoff walls overlap, or a seepage cutoff wall begins or ends without overlapping with another seepage cutoff wall were reviewed. Existing levee improvements include the concrete retaining wall from Station 1023+30 to 1024+70 and Old Sacramento Floodwall from Station 1040+90 to 1082+40 that do not intersect with other seepage cutoff walls. These walls are discussed in Sections 2.7.1 and 2.7.2 respectively. A berm was constructed between Stations 1013+00 and 1020+50 24001006.001A/SAC24R176178 Page 39 of 57 April 17, 2025 © 2025 Kleinfelder
to widen the existing levee prism due to waterside levee slope and riverbank erosion. A buried curb wall between Stations 1731+50 and 1765+92 was installed to address freeboard issues. The buried curb wall ties into a floodwall at Station 1765+92 that also addresses freeboard issues. Levee improvement transitions outside the SREL-A through SREL-E segment areas defined in this report are being evaluated by GEI. Levee improvement transitions within the subject portions of SREL are presented in Table 2.11. 24001006.001A/SAC24R176178 Page 40 of 57 April 17, 2025 © 2025 Kleinfelder
Table 2.11
Levee Improvement Transitions
ARSLS
Reach
Transition Overlap Station
Transition
Tip
Elevations
(ft)
Beginning Record Drawings Transition Evaluation Report Meets ULDC Station
Ending
Station
Overlap
Width
(ft)
A
-- 1009+50 N/A
End of 2000 USACE SCB open-trench cutoff wall
(Extension of ARSL cutoff wall project) to no cutoff
wall
-39.5
Kleinfelder, 2022. Geotechnical Data Report, American River Common Features 2016, Sacramento River East Levee, Contracts 3 and 4, Sacramento County, California, Contract No.: W91238-16D-0019, Task Order W91238- 20-F-0080, USACE Project No.: 456852. Issue Date May 24, 2021. Revised October 14, 2022.

Figure 5-2
Kleinfelder, 2016. ULDC Geotechnical Results
Summary, Sacramento River East Levee
Downstream of American River, SAFCA FEMA Levee
Accreditation (North Area Streams, American River,
Sacramento River Downstream of American River,
and Beach Lake Levee), Dated April 29, 2016
Yes
1013+00 1020+50 N/A Extents of berm at Robert T. Matsui Waterfront Park (no cutoff wall)1
Top of berm:
40 to 45
Kleinfelder, 2022. Geotechnical Data Report, American River Common Features 2016, Sacramento River East Levee, Contracts 3 and 4, Sacramento County, California, Contract No.: W91238-16D-0019, Task Order W91238- 20-F-0080, USACE Project No.: 456852. Issue Date May 24, 2021. Revised October 14, 2022.

Figure 5-2
URS, 2014. “Geotechnical Evaluation Report,
Volume 1, Existing Conditions, Sacramento River
Study Area.” Dated July 2014.

Yes
Stations 1080+00 to 1150+00 evaluated by GEI
B Stations 1150+00 to 1185+00 no transitions
Stations 1185+00 to 1206+00 evaluated by GEI
C
1206+00 1207+75 175
2020 USACE SB open-trench cutoff wall to 1991-
1993 USACE SCB mix-in-place cutoff wall
(Sacramento Urban Area Phase II cutoff wall)
-35 to 15
GEI Consultants/HDR (2020). As-Built, Dated 12/21/2020, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.: W91238-23-B-0003. Contract No.:

W91238-23-C-0004. Prepared by GEI Consultants/HDR for the United States Army Corps of Engineers, Sacramento District. Issue Date: 4 November 2019.

Plan Sheet C-004
GEI Consultants/HDR (2019). Final Design
Documentation Report, American River Common
Features 2016, Sacramento River East Levee -
Contract 1, Sacramento County, California. Dated
November 2019.

Yes
-- 1224+75 N/A
1991-1993 USACE SCB DMM cutoff wall
(Sacramento Urban Area Phase II cutoff wall) to
high ground/no cutoff wall
16 Kleinfelder (2021). Geotechnical Data Report, American River Common Features 2016, Sacramento River East Levee Contracts 3 and 4
Figure 5-4
URS (2014). Geotechnical Evaluation Report,
Volume 1, Existing Conditions, Sacramento River
Study Area. Dated July 2014.

Yes
1244+73 -- N/A Beginning of 2024 USACE SC jet grout cutoff wall -30 Maloney Odin, A Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4.

Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Plan Sheet C-003
Kleinfelder (2023). Supplemental Geotechnical
Analysis Memorandum Contract 4 Reaches,
American River Common Features 2016,
Sacramento River East Levee, Contract 4. Dated
January 26, 2023.

Yes
1247+50 1247+64 14 2024 USACE SC jet grout cutoff wall to 2024 USACE SCB DMM cutoff wall -30
Maloney Odin, A Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4.

Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Yes
1261+47 1261+80 33 2024 USACE SCB DMM cutoff wall to 2003 SAFCA SCB DMM cutoff wall -46 to -52.7
Maloney Odin, A Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4.

Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Plan Sheet C-004
Kleinfelder (2023). Supplemental Geotechnical
Analysis Memorandum Contract 4 Reaches,
American River Common Features 2016,
Sacramento River East Levee, Contract 4. Dated
January 26, 2023.

Yes
1282+90 1285+50 260 2003 SAFCA SCB DMM cutoff wall to 2020 USACE SCB DMM cutoff wall -65 to -90
GEI Consultants/HDR (2020). As-Built, Dated 12/21/2020, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.: W91238-23-B-0003. Contract No.:

W91238-23-C-0004. Prepared by GEI Consultants/HDR for the United States Army Corps of Engineers, Sacramento District. Issue Date: 4 November 2019.

Plan Sheet C-005
GEI Consultants/HDR (2019). Final Design
Documentation Report, American River Common
Features 2016, Sacramento River East Levee -
Contract 1, Sacramento County, California. Dated
November 2019.

Yes
Stations 1285+75 to 1418+00 evaluated by GEI
D
1424+20 1424+50 30 2006 USACE SCB DMM cutoff wall to 2022 USACE SCB DMM cutoff wall -77 to -74
Maloney Odin, Joint Venture (2024). Final As-Built, Dated 03/29/2024, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 3. Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Original Issue Date: 21 October 2021.

Plan Sheet C-001
Kleinfelder (2021). Final – Revision 1, Supplemental
Geotechnical Analysis Memorandum Contract 3
Reaches, American River Common Features 2016,
Sacramento River East Levee, Contract 3. Dated
September 10, 2021.

Yes
1438+50 1439+00 50 2022 USACE SCB DMM cutoff wall to 2022 USACE SB open-trench cutoff wall -71 to -62
Maloney Odin, Joint Venture (2024). Final As-Built, Dated 03/29/2024, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 3. Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Original Issue Date: 21 October 2021.

Plan Sheet C-002
Kleinfelder (2021). Final – Revision 1, Supplemental
Geotechnical Analysis Memorandum Contract 3
Reaches, American River Common Features 2016,
Sacramento River East Levee, Contract 3. Dated
September 10, 2021.

Yes
1487+00 1487+30 30 2022 USACE SB open-trench cutoff wall to 2022 USACE SCCB open-trench cutoff wall -51
Maloney Odin, Joint Venture (2024). Final As-Built, Dated 03/29/2024, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 3. Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Original Issue Date: 21 October 2021.

Plan Sheet C-007
Kleinfelder (2021). Final – Revision 1, Supplemental
Geotechnical Analysis Memorandum Contract 3
Reaches, American River Common Features 2016,
Sacramento River East Levee, Contract 3. Dated
September 10, 2021.

Yes
1497+70 1498+00 30 2022 USACE SCCB open-trench cutoff wall to 2022 USACE SB open-trench cutoff wall -51
Maloney Odin, Joint Venture (2024). Final As-Built, Dated 03/29/2024, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 3. Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Original Issue Date: 21 October 2021.

Plan Sheet C-008
Kleinfelder (2021). Final – Revision 1, Supplemental
Geotechnical Analysis Memorandum Contract 3
Reaches, American River Common Features 2016,
Sacramento River East Levee, Contract 3. Dated
September 10, 2021.

Yes
1519+76 1520+06 30
2022 USACE SB open-trench hanging cutoff wall
to 2022 USACE SCB DMM fully-penetrating cutoff
wall
-51 to -110
Maloney Odin, Joint Venture (2024). Final As-Built, Dated 03/29/2024, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 3. Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Original Issue Date: 21 October 2021.

Plan Sheet C-010
Kleinfelder (2021). Final – Revision 1, Supplemental
Geotechnical Analysis Memorandum Contract 3
Reaches, American River Common Features 2016,
Sacramento River East Levee, Contract 3. Dated
September 10, 2021.

Yes
24001006.001A/SAC24R176178 Page 41 of 57 April 17, 2025 © 2025 Kleinfelder
ARSLS
Reach
Transition Overlap Station
Transition
Tip
Elevations
(ft)
Beginning Record Drawings Transition Evaluation Report Meets ULDC Station
Ending
Station
Overlap
Width
(ft)
1530+45 1530+60 15 2022 USACE SCB DMM fully-penetrating cutoff wall to 2022 USACE SCB DMM cutoff wall -110 to -105
Maloney Odin, Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.:

W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Plan Sheet C-005
Kleinfelder (2023). Supplemental Geotechnical
Analysis Memorandum Contract 4 Reaches,
American River Common Features 2016,
Sacramento River East Levee, Contract 4. Dated
January 26, 2023.

Yes
1531+06 1531+20 14 2022 USACE SCB DMM cutoff wall to 2024 USACE SC jet grout cutoff wall -105
Maloney Odin, Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.:

W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Yes
1533+03 1533+32 29 2024 USACE SC jet grout cutoff wall to 2022 USACE SCB DMM cutoff wall extension -105
Maloney Odin, Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.:

W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Yes
1534+00 1534+30 30 2022 USACE SCB DMM cutoff wall extension to 2020 USACE SCB DMM cutoff wall -105 to -102
Maloney Odin, Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.:

W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Yes
Stations 1534+40 to 1640+00 evaluated by GEI
E
-- 1640+00 N/A End of 2020 USACE SB open-trench cutoff wall -55 GEI Consultants/HDR (2020). As-Built, Dated 12/21/2020, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.: W91238-23-B-0003. Contract No.:

W91238-23-C-0004. Prepared by GEI Consultants/HDR for the United States Army Corps of Engineers, Sacramento District. Issue Date: 4 November 2019.

Plan Sheet C-019
GEI Consultants/HDR (2019). Final Design
Documentation Report, American River Common
Features 2016, Sacramento River East Levee -
Contract 1, Sacramento County, California. Dated
November 2019.

Yes
-- 1678+35 N/A Beginning of 2024 USACE Concrete Buried Curb Wall 27.5
Maloney Odin, A Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4.

Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Plan Sheet C-006
Kleinfelder (2023). Supplemental Geotechnical
Analysis Memorandum Contract 4 Reaches,
American River Common Features 2016,
Sacramento River East Levee, Contract 4. Dated
January 26, 2023.

Yes
1689+07 1690+00 N/A
1991-1993 USACE SCB mix-in-place cutoff wall
(Sacramento Urban Area Phase II cutoff wall)
window at abandoned pipe.

Drained Stability Berm to remediate potential
concentrated leak erosion around pipe
19 to 9
Maloney Odin, A Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4.

Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Plan Sheet C-007
Kleinfelder (2023). Supplemental Geotechnical
Analysis Memorandum Contract 4 Reaches,
American River Common Features 2016,
Sacramento River East Levee, Contract 4. Dated
January 26, 2023.

Yes
1729+12 1729+72 60
Window in 1991-1993 USACE SCB mix-in-place
cutoff wall (Sacramento Urban Area Phase II
cutoff wall) at Freeport Bridge
Widened embankment from roadway fill
6 American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.: W91238-23-B0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Plan Sheet C-011
Kleinfelder (2023). Supplemental Geotechnical
Analysis Memorandum Contract 4 Reaches,
American River Common Features 2016,
Sacramento River East Levee, Contract 4. Dated
January 26, 2023.

Yes
1735+18 1735+58 40
Window in 1991-1993 USACE SCB mix-in-place
cutoff wall (Sacramento Urban Area Phase II
cutoff wall) at Sewer Outfall
4 American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.: W91238-23-B0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Plan Sheet C-012
Kleinfelder (2023). Supplemental Geotechnical
Analysis Memorandum Contract 4 Reaches,
American River Common Features 2016,
Sacramento River East Levee, Contract 4. Dated
January 26, 2023.

Yes
1755+62 1755+95 33
1991-1993 USACE SCB mix-in-place cutoff wall
(Sacramento Urban Area Phase II cutoff wall) to
2006 USACE SCB open-trench cutoff wall
10 to -9
American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.: W91238-23-B0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Plan Sheet C-014
Kleinfelder (2023). Supplemental Geotechnical
Analysis Memorandum Contract 4 Reaches,
American River Common Features 2016,
Sacramento River East Levee, Contract 4. Dated
January 26, 2023.

Yes
-- 1765+92 N/A 2024 USACE Concrete Buried Curb Wall to
Floodwall2 28 to 30.5
Maloney Odin, A Joint Venture (2024). As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4.

Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder/Stantec for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

Plan Sheet C-015
Kleinfelder (2023). Supplemental Geotechnical
Analysis Memorandum Contract 4 Reaches,
American River Common Features 2016,
Sacramento River East Levee, Contract 4. Dated
January 26, 2023.

Yes

1. Berm was installed to expand the levee prism due to waterside erosion.

2. Buried curb wall and floodwall were installed to address freeboard. 24001006.001A/SAC24R176178 Page 42 of 57 April 17, 2025 © 2025 Kleinfelder
In general, according to as-built record drawings, seepage cutoff walls of different types overlapped by at least 14 feet. Based on review of the corresponding transition evaluation reports, the seepage cutoff wall transitions do not present three-dimensional effects that would present performance issues.

Therefore, it is Kleinfelder’s opinion that the seepage cutoff wall transitions meet the geotechnical requirements of ULDC 7.9 Interfaces and Transitions.

2.6.2 Encroachment Interfaces
Several types of encroachment interfaces occur through the levee prism. Mead and Hunt evaluated the structural properties of these interfaces in their 2025 ARSLS Due Diligence Report. Kleinfelder reviewed the Mead & Hunt 2025 report, available as-built records, existing conditions, and/or past performance history of these interfaces to evaluate if they presented gaps in features, loading or demand concentrations, or other three-dimensional effects that would cause them to not meet geotechnical criteria.

Non-permitted encroachments such as those built by homeowners are under the purview of the Central Valley Flood Protection Board (CVFPB) and the specified Levee Maintaining Agency (LMA) for that reach.

CVFPB has implemented a program to remove non-permitted encroachments, and these encroachments are considered low risk with regards to geotechnical levee criteria (i.e. they are above the DSWE or penetrate less than 5 feet into the levee surface/prism). The LMAs for SREL in the ARSLS are:
• American River Flood Control District: Stations 1000+00 to 1020+00 • City of Sacramento: Stations 1020+00 to 1215+00
• Maintenance Area 9: Stations 1215+00 to 1770+00

2.6.2.1 Railroad Tracks
Railroad tracks encroach on the levee between the following stations:
• Stations 1040+00 to 1199+00
• Stations 1678+00 to 1770+00
The railroad tracks were built for commercial purposes; however, they are now owned by California State Parks. The northern set of tracks are used for tourist excursion trains from Old Sacramento and the southern set of tracks are abandoned and not in use. Because the railroad tracks are located above the freeboard, they are not considered a risk to the levee stability of the levee. The SREL Contract 4 24001006.001A/SAC24R176178 Page 43 of 57 April 17, 2025 © 2025 Kleinfelder
Kleinfelder SGAM also performed seepage and stability sensitivity analyses that included loading from trains, and the results met criteria. Therefore, it is Kleinfelder’s opinion that the railroad track encroachments meet the geotechnical requirements of ULDC 7.9 Interfaces and Transitions.

2.6.2.2 Pump Stations
The pump stations located along SREL feature pipes that pass through the levee prism. These include the following:
• City of Sacramento Intake Pipes at Station 1010+05 (CVFPB Permit #11654) • City of Sacramento Water Intake at Station 1015+75 (CVFPB Permit #17196) • Sump 163 (Railyards Sump Station) at Station 1027+80 (CVFPB Permit #19134) • Pump Station, Water Collection #1 at Station 1174+00 (CVFPB Permit #2043) • Sump 41 at Station 1256+67 (CVFPB Permit #14143)
• Sump 70 at Station 1425+06 (CVFPB Permit #3981)
• Sump 132 at Station 1532+00 (CVFPB Permit #9205)
• Freeport Water Intake at Station 1665+00 (CVFPB Permit #18061) • City of Sacramento Drainage Pipes at Station 1668+66 (CVFPB Permit #2365) • City of Sacramento Sump 28 at Station 1668+81 (CVFPB Permit #17604) • Sump 34 at Station 1678+20 (CVFPB Permit #2390)
• Sacramento Regional Wastewater Treatment Plant Outfall Pipe at Station 1735+40 (CVFPB Permit #9739)
o Pipe invert Elevation +21.5 feet is below the 2025 DWSE at this station. As part of the SREL Contract 4 SGAM, Kleinfelder modeled the wastewater treatment plant outfall pipe and analyzed this area for underseepage and through seepage criteria (Kleinfelder, 2023). The location met geotechnical criteria.
24001006.001A/SAC24R176178 Page 44 of 57 April 17, 2025 © 2025 Kleinfelder
According to Appendix A of the 2025 Mead & Hunt Due Diligence Report, no pump station pipe penetrations through SREL other than the outfall pipe at Station 1735+40 have invert elevations below the 2025 DWSE. There has not been a report of poor past performance at these locations during previous high water events (URS, 2014). Therefore, it is Kleinfelder’s opinion that the pump station encroachments meet the geotechnical requirements of ULDC 7.9 Interfaces and Transitions.

2.6.2.3 Bridge Piles
Three bridges are located along SREL: I Street Bridge, Tower Bridge, and Freeport Bridge. Driven piles with concrete caps intersect the waterside of the levee. Details about the bridge piles and approximate intersection with and proximity to the levee are described in Table 2.12. Piles driven through the levee crown are assumed to extend through at least the height of the levee prism.

Table 2.12
Bridge Pile Encroachments Within the ARSLS
Bridge Name
and Station Details References Meets ULDC Criteria
I Street Bridge
1039+00
The SREL bridge abutment is located along the over
widened levee crown 20 feet east of the floodwall. The
next abutment is 70 feet east of the floodwall. Based on nearby projects along the riverbank, it is assumed the
abutment is supported by driven concrete or timber piles.

The eastmost pier is within the river channel and
approximately 75 feet west of the waterside levee toe. I Street Bridge piers appear to be caissons excavated into the cobble layer below the river. The pier is not expected to affect levee performance because it is located too far from the levee prism.

Google Earth;
Southern
Pacific Co.

Order Diagram
for Sacramento
River Bridge
(June 1910)
Yes, due to
performance
history
Tower Bridge
1060+50
Two abutments are located within the levee prism. One is located approximately on the waterside toe of SREL, the other is approximately 25 feet east of the waterside toe and intersects the overwidened levee crown. Based on
the piles used to construct the abutment for the west side of the bridge, it is assumed the abutment piles within the levee are reinforced concrete.

A fixed truss span connects the waterside toe abutment
to the waterside bridge pier, which is located within the river channel approximately 140 feet west of the
waterside toe. This pier is not expected to affect levee performance because it is located too far from the levee prism.

GeoDOG;

SACRAMENTO

RIVER (TOWER

BRIDGE)
(220021)
03 - YOL - 275 -
PM 13.07 -
General
Foundation
Yes, due to
performance
history
24001006.001A/SAC24R176178 Page 45 of 57 April 17, 2025 © 2025 Kleinfelder
Bridge Name
and Station Details References Meets ULDC Criteria
Freeport
Bridge
1729+45
The SREL bridge abutment is located along the waterside slope approximately 30 feet east of the waterside levee toe. The levee crown width is overwidened at the bridge (appx. 100 feet). Based on the construction details of the other bridges, it can be assumed the abutments contain
driven concrete or timber piles.

The east pier is approximately 65 feet west of the
waterside levee toe. The piles within this pier are not expected to affect levee performance because it is
located too far from the levee prism.

Google Earth
Yes, due to
performance
history
Ultimately these bridge piles are considered to meet ULDC geotechnical criteria due to past performance. MBK is evaluating the ARSLS for erosion and scour that may affect the bridge piles.

Intersection with the waterside toe is not anticipated to impair seepage and stability performance, especially considering the overwidened and elevated levee geometry (refer to Section 2.5). Therefore, it is Kleinfelder’s opinion that the bridge pile encroachments meet the geotechnical requirements of ULDC

7.9 Interfaces and Transitions.

2.6.2.4 Retaining Wall Encroachments
Retaining walls are considered an interface because they encroach upon and reduce the levee prism.

Mead & Hunt’s report list of ARSLS retaining walls with SAFCA IDs is attached in Appendix E, the walls with stations identified within the ULDC range covered in this report are highlighted.

From a geotechnical standpoint, these retaining walls are considered low risk features for the ARSLS because of the existing levee flood control measures. The retaining walls highlighted in Appendix E are located at stations where a seepage cutoff wall was built at the levee (see Table 2.11):
• Stations 1263+52 through 1266+78:
o 2003 SAFCA SCB DMM cutoff wall
• Stations 1449+37 through 1453+68:
o 2022 USACE SB open-trench cutoff wall
• Station 1532+78:
o 2024 USACE SC jet grout cutoff wall
• Stations 1718+49 through 1720+48:
o 1991-1993 USACE SCB mix-in-place cutoff wall
24001006.001A/SAC24R176178 Page 46 of 57 April 17, 2025 © 2025 Kleinfelder
Although not every retaining wall in Appendix E has a station or address identified, the majority are located in the Pocket area, where residences are typically located within 100 feet of the landside toe.

Seepage cutoff walls built here are expected to reduce the underseepage gradient to the point where any impact of the retaining wall on the levee’s integrity is negligible. The retaining walls are also not built far enough into the prism to affect slope stability; Mead and Hunt came to the same conclusion for all ARSLS retaining walls in their report (Mead & Hunt, 2025). As discussed above, these encroachments are generally not permitted and are part of the CVFPB program to remove encroachments. It is Kleinfelder’s opinion that the non-permitted retaining wall encroachments located within ARSLS do not negatively impact the levee from a geotechnical standpoint. Permitted retaining walls are associated with other structures like pump stations and bridge abutments and do not negatively impact the levee from a geotechnical standpoint. Therefore, it is Kleinfelder’s opinion that the retaining walls located within ARSLS meet the interface geotechnical requirements of ULDC, as well as the criteria of ULDC Section 7.14 (discussed in Section 2.7).

2.6.2.5 Other Major Structures and Encroachments
Various other structures create interfaces with the levee throughout ARSLS, such as the Westin hotel on the landside berm at Station 1245+00. Where applicable, these structures were reviewed as part of Kleinfelder’s 2023 SGAM, and their effects were implemented into the SGAM seepage and stability evaluations. These encroachments are considered to meet ULDC criteria provided that they are properly maintained under the purview of their respective LMA.

Based on review of the as-built drawings and existing conditions, the encroachment interfaces do not present gaps or other three-dimensional effects. Therefore, it is Kleinfelder’s opinion that the subject portions of SREL encroachment interfaces meet the geotechnical requirements of ULDC 7.9 Interfaces and Transitions.

2.6.3 Transition Between American River South Levee and Sacramento River East Levee at Station 1000+00
The transition between ARSL and SREL occurs at Station 1000+00. The SCB slurry trench seepage cutoff wall described in Table 2.11 wraps around from the American River confluence to SREL Station 1009+50.

The seepage cutoff wall and levee geometry are continuous through this transition between levee systems. This results in a transition in stationing, not features. Because the critical cross section modeling the seepage cutoff wall at Station 1005+00 (Kleinfelder, 2016) meets underseepage and slope 24001006.001A/SAC24R176178 Page 47 of 57 April 17, 2025 © 2025 Kleinfelder
stability ULDC criteria as shown in Tables 2.6 and 2.7, the transition between levee systems also meets ULDC criteria.

2.6.4 Transition Between Sacramento River East Levee and Beach Lake North Levee at Station 1770+00
The transition between SREL and BLNL occurs at River Road at Station 1770+00. It is a perpendicular intersection of the two levee alignments. South of Station 1770+00, SREL continues along the riverbank, is no longer part of the ARSLS, and does not have FEMA certification or evaluation per ULDC. Although this levee reach is not included as part of the ARSLS, a levee breach in this reach could risk damage to the SREL and BLNL levees, as discussed in Appendix H of the SREL Contract 4 SGAM (Kleinfelder, 2023).

The following flood control improvements were implemented along SREL near the described transition area during the SREL Contract 4 construction project (Maloney Odin, A Joint Venture, 2024):
• Floodwall raised from Stations 1765+92 to 1770+46
• Flashboard raised from Stations 1770+46 to 1772+90
• DMM seepage cutoff wall constructed to tip Elevation -15 feet from Stations 1770+12 to 1774+00
• Seepage and stability berm constructed from Stations 1771+91 to 1774+00 Seepage and stability analyses were modeled with the above remediations in the SREL Contract 4 SGAM at Stations 1772+00 and 1775+00. The results meet underseepage and slope stability criteria. As such, it is Kleinfelder’s opinion that the transition from SREL to BLNL meets ULDC criteria.

2.6.5 Conclusion
Based upon the above information, it is Kleinfelder’s opinion that the above interfaces and transitions meet the geotechnical requirements of ULDC (DWR, 2012) Section 7.9 Interfaces and Transitions. 24001006.001A/SAC24R176178 Page 48 of 57 April 17, 2025 © 2025 Kleinfelder

2.7 ULDC SECTION 7.14 FLOODWALLS, RETAINING WALLS, AND CLOSURE STRUCTURES This evaluation included review of the construction details, inspection records, and performance history of specific structures in relation to the geotechnical aspects of seepage, slope stability, and future settlement potential as applicable to the ULDC criteria. Mead & Hunt evaluated the structural integrity of these features with regard to ULDC Section 7.14. The floodwalls, retaining walls, and closure structures are listed with their SAFCA IDs and location information in Appendix E, which was sourced from the Mead & Hunt 2025 Due Diligence report. No new analyses or field investigations were performed for this evaluation.

Each floodwall is discussed in Sections 2.7.1 through 2.7.3 below. Retaining walls meet the geotechnical criteria of ULDC Section 7.14 for the same reasons they meet ULDC interfaces criteria; see Section

2.6.2.3. Closure structures identified in Appendix E were either not within the reaches covered in this report or located behind the Old Sacramento floodwall, where they do not inhibit levee geotechnical performance.

2.7.1 Waterside Concrete Retaining Wall, Stations 1023+30 to 1024+70 Kleinfelder performed a site visit in November 2024 and observed the mechanically stabilized earth (MSE) retaining wall at the upper waterside slope of SREL from approximately Station 1023+30 to 1024+70. It is understood that MSE retaining wall was constructed by the City of Sacramento to support the bike path next to Jibboom Street. The area behind the wall is above the HTOL, the levee prism is contained with an area of high ground formed by Jibboom Street and the I-5 embankment, and no penetrations occur through the retaining wall. It is Kleinfelder’s opinion that this floodwall does not negatively impact the levee from a geotechnical standpoint. This structure has been in place since the early 2000s; therefore, it is unlikely this structure will induce additional settlement of the underlying/adjacent levee embankment.

2.7.2 Old Sacramento Floodwall and Riverwalk Promenade, Station 1040+90 to 1082+40 A concrete gravity floodwall was originally constructed by the Southern Pacific Railroad in the Old Sacramento area (SREL-A) in 1913 (URS, 2014) and extended to just beyond the Tower Bridge (Station 1060+50). As-built plans for the original floodwall construction are not available (URS, 2014). The City of Sacramento constructed the Riverwalk Promenade south of Tower Bridge in 1981 to about Station 1080+00 and extended the wall and the Riverwalk Promenade to about Station 1082+40 in 2008. An approximately 500-foot portion of the concrete gravity floodwall was replaced with a sheet pile wall 24001006.001A/SAC24R176178 Page 49 of 57 April 17, 2025 © 2025 Kleinfelder
along Tower bridge in 1987. The construction improvement and performance history is summarized in the list below.
• City of Sacramento constructed the Riverwalk Promenade south of Tower Bridge (1060+50) in 1981 to about Station 1080+00.
• Sections of the wall between Stations 1040+00 and 1047+00 have been demolished. A reinforced earth retaining wall and a concrete stem wall were built in 1982 to provide upgraded flood control for this region (URS, 2014).
• In 1984, the City of Sacramento installed tieback anchors into the concrete gravity wall and backfill between approximate Stations 1047+00 and 1056+50 (USACE, 1995). • USACE observed erosion at the toe of the floodwall after the February 1986 flood, reportedly resulting in cavities beneath the wall foundation (URS, 2014). • In 1987, an approximately 500-foot-long portion of the floodwall located between Stations 1057+79 and 1062+54 failed due to a suspected waterline break (Kleinfelder, 2016). A steel sheet pile wall supported by deadman anchors was installed between these stations to approximate tip elevation -18 feet (Harding Lawson Associates, 1997). • Tieback anchors that were reportedly 55 feet long, installed 15 feet on center, and designed for a capacity of 75 kips each, were installed by USACE in 1995 to reinforce the floodwall between approximately Stations 1047+00 and 1060+00 (URS, 2014). • City of Sacramento extended the Riverwalk Promenade to about Station 1082+40 in 2008. • Dewatering wells and groundwater sensor wells were constructed in 2008 by Caltrans in the landside field area between Front Street and the west side of the I-5 depressed section retaining wall near N Street, P Street, and Q Street (between Stations 1065+00 and 1076+00) (Kleinfelder, 2016). These wells were installed to reduce groundwater uplift pressures from beneath the I-5 depressed section. Operation and maintenance of this dewatering system are under the jurisdiction of Caltrans (URS, 2014).

USACE evaluated the gravity floodwall for geotechnical and structural criteria in 1995. Regarding settlement, USACE concluded that any remaining settlement for the backfill behind the wall should be 24001006.001A/SAC24R176178 Page 50 of 57 April 17, 2025 © 2025 Kleinfelder
considered negligible, as the original construction took place in 1913 (USACE, 1995). Future construction of new structures that apply loading to the backfill may cause additional settlement.

In the ULDC Geotechnical Results Summary, Kleinfelder characterized Station 1040+00 to 1080+00 as an analytical reach due to the presence of the flood walls, consistent stratigraphy, and high ground extending landside of the floodwalls. Between Stations 1040+00 to 1060+00, the landside elevation is generally between Elevation 22 and 38 feet. Downstream of Stations 1060+00, the landside elevation located over 100 feet landside of the floodwall, is between 8 and 16 feet along Interstate 5. According the ULDC Goetechnical Results Summary, Station 1072+00 was selected as the critical cross section due to the lowest landside elevation area that is located within the depressed section of Interstate 5.

Kleinfelder analyzed Station 1072+00 including the waterside floodwall and landside retaining wall for global landside slope stability, global waterside rapid drawdown stability, and underseepage conditions (Kleinfelder, 2016). The analysis did not consider localized stability of the floodwalls and retaining wall which is being evaluated by Mead and Hunt. The concrete gravity and sheet pile floodwalls provide freeboard and prevent through seepage. The results of these analyses meet the slope stability and seepage ULDC criteria for intermittently-loaded levees through exception, as they rely on the Caltrans dewatering system. It should be noted that the end of the wall transition at Station 1082+40 is not within Kleinfelder’s ULDC reach and will be evaluated by GEI.

The levee segment along the sheet pile portion of the floodwall from Stations 1057+79 to 1062+64 has similar stratigraphy to 1072+00 and a higher landside area, therefore it also meets ULDC stability and seepage criteria.

Based on the topography and geotechnical analysis results, it is Kleinfelder’s opinion that the Old Sacramento concrete gravity and steel sheet pile floodwalls meet the geotechnical requirements of ULDC. It should be noted that the evaluation of structural integrity, operations, and maintenance for the walls shall be performed by Mead and Hunt. These structures were constructed and later reinforced between 1914 and 2008; therefore, it is unlikely these structures will induce additional settlement of the underlying levee embankment.

2.7.3 Cliff’s Marina Floodwall and Flashboard Closure, Stations 1765+92 to 1772+90 A 12-inch-wide cast-in-place concrete floodwall was built at the waterside of the levee crown from Station 1765+92 to 1770+46. The base of the wall is located at Elevation 27.8 feet and abuts against the Cliffs Marina flashboard closure, which extends the freeboard protection across Cliff’s Marina parking lot to the levee crown. The existing flashboard system is located directly downstream of the floodwall at 24001006.001A/SAC24R176178 Page 51 of 57 April 17, 2025 © 2025 Kleinfelder
Station 1770+46 and runs for approximately 244 linear feet to approximately Station 1772+90 where it ties into the levee crown. The flashboard system consists of 6-inch by 6-inch steel sleeves embedded in unreinforced concrete drilled shafts up to 4.5 feet below ground surface spaced approximately every 8 feet along the flashboard alignment. Aluminum posts consisting of 5-inch deep I beams are placed into the sleeves with 4-inch by 6-inch boards placed between the posts to complete the wall. The SREL Contract 4 project raised the floodwall to Elevation 31.2 feet in 2023 (Maloney Odin, A Joint Venture, 2024). Mead & Hunt also performed a 2024 field inspection and found the wall satisfactory with no defects (Mead & Hunt, 2025). It is Kleinfelder’s opinion that this floodwall and flashboard closure meet the geotechnical requirements of ULDC. These structures have been in place since the 2006 and the 2023 floodwall raise was less than one foot; therefore, it is unlikely these structures will induce additional settlement of the underlying levee embankment.

2.7.4 Conclusion
Based upon the above data, Kleinfelder concludes that the floodwalls, retaining walls, and closure structures described above and located within the ARSLS levee prism meet the geotechnical requirements of ULDC 7.14 Floodwalls, Retaining Walls, and Closure Structures for settlement, seepage, and slope stability. It should be noted that Kleinfelder did not evaluate the structures as far as conformance with structural integrity, operations, or maintenance per ULDC. It is our understanding this evaluation will be performed by Mead and Hunt.
24001006.001A/SAC24R176178 Page 52 of 57 April 17, 2025 © 2025 Kleinfelder
3 AMERICAN RIVER SOUTH LEVEE SYSTEM STUDY AREA SUMMARY OF RESULTS ___________________________________________________________________________________ Based on the review summarized in Section 2, above, Table 3.1 includes those reaches that in Kleinfelder’s opinion meet or do not meet the geotechnical aspects of the ULDC (DWR, 2012) for Sections 7.3 Soil Sampling, Testing, and Logging, 7.4 Slope Stability for Intermittently Loaded Levees, 7.5 Underseepage for Intermittently Loaded Levees, 7.7 Seismic Vulnerability, 7.8 Levee Geometry, 7.9 Interfaces and Transitions, and 7.14 Floodwalls, Retaining Walls, and Closure Structures.

Table 3.1
Levee Reaches Meeting Geotechnical Aspects of ULDC Criteria Project
Levee
Approximate Levee
Stationing
Meets
Criteria
Does Not
Meet
Criteria
ULDC Criteria Section
SREL
1000+00 to 1080+00
1150+00 to 1185+00
1206+00 to 1285+75
1418+00 to 1534+40
1640+00 to 1770+00
X

7.3 Soil Sampling, Testing, and
Logging

7.4 Slope Stability for Intermittently
Loaded Levees1

7.5 Underseepage for Intermittently
Loaded Levees2

7.7 Seismic Vulnerability

7.8 Levee Geometry

7.9 Interfaces and Transitions

7.14 Floodwalls, Retaining Walls, and
Closure Structures

1. Meets criteria through Exception. See Section 2.2 for discussion of the exception.

2. Meets criteria through Exception. See Section 2.3 for discussion of the exception.

It is Kleinfelder’s opinion that the subject portions of SREL outlined above meet the geotechnical aspects of the ULDC as outlined in Table 3.1. To meet 7.7 Seismic Vulnerability as required by the ULDC, a Post Earthquake Remedial Plan is being prepared to address remediation of subject portions of SREL as a result of a seismic event. Since Sections 7.4 Slope Stability for Intermittently Loaded Levees and 7.5 Underseepage for Intermittently Loaded Levees meet through exception for the I-5 depressed section, it is recommended that a flood fighting plan be developed for the I-5 depressed section that does not include the Caltrans dewatering system.
24001006.001A/SAC24R176178 Page 53 of 57 April 17, 2025 © 2025 Kleinfelder
4 LIMITATIONS
___________________________________________________________________________________ This work was performed in a manner consistent with that level of care and skill ordinarily exercised by other members of Kleinfelder’s profession practicing in the same locality, under similar conditions and at the date the services are provided. The work performed was based on project information provided by client and from publicly available sources. Kleinfelder’s conclusions, opinions, and recommendations are based on a limited number of observations and data. It is possible that conditions could vary between or beyond the data evaluated. Kleinfelder makes no other representation, guarantee, or warranty, express or implied, regarding the services, communication (oral or written), report, opinion, or instrument of service provided. This report may be used only by the client and the registered design professional in responsible charge and only for the purposes stated for this specific engagement within a reasonable time from its issuance, but in no event later than two years from the date of the report.

The scope of services was limited. It should be recognized that definition and evaluation of subsurface conditions are difficult. Judgments leading to conclusions and recommendations are generally made with incomplete knowledge of the subsurface conditions present due to the limitations of data from field studies. The conclusions of this assessment are based on the information presented herein.

Although risk can never be eliminated, more detailed and extensive studies yield more information, which may help understand and manage the level of risk.

All rivers, streams and lakes will flood eventually. This fact means that all levees will be called upon to combat floodwaters at some point. Levees reduce the risk of flooding. But no levee system can eliminate all risk of flooding. The term “certification” is not intended to provide a guarantee or warranty of the conditions of the levee or its performance and assumes the following 1) a certification by a registered professional engineer or other party does not constitute a warranty or guarantee of performance, expressed or implied; 2) certification of data is a statement that the data is accurate to the best of the certifier’s knowledge; and 3) certification of analyses is a statement that the analyses have 24001006.001A/SAC24R176178 Page 54 of 57 April 17, 2025 © 2025 Kleinfelder
been performed correctly and in accordance with sound engineering practices. A levee certification does not address or mitigate the inherent flood risk proposed to a particular community. 24001006.001A/SAC24R176178 Page 55 of 57 April 17, 2025 © 2025 Kleinfelder
5 REFERENCES
___________________________________________________________________________________ Department of Water Resources, California, 2009. “Division of Flood Management Soil and Rock Logging, Classification, Description and Presentation Manual.” Dated September 2009.

Department of Water Resources, California, 2012. “Urban Levee Design Criteria, State of California, Department of Water Resources.” Dated May 2012.

Department of Water Resources, California, 2015. “Guidance Document for Geotechnical Analyses, Urban Levee Geotechnical Evaluations Program.” Dated April 27, 2015.

GEI Consultants/HDR, 2016. “Embankment and Foundation Stability Memorandum, Sacramento River East Levee Improvement Project, Sacramento County, California,” dated August 2016.

GEI Consultants/HDR, 2019. Final Design Documentation Report, American River Common Features 2016, Sacramento River East Levee - Contract 1, Sacramento County, California. Dated November 15, 2019.

GEI Consultants/HDR, 2020. As-Built, Dated 12/21/2020, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.: W91238-23- B-0003. Contract No.: W91238-23-C-0004. Prepared by GEI Consultants/HDR for the United States Army Corps of Engineers, Sacramento District. Issue Date: 4 November 2019.

Harding Lawson Associates, 1997. Geotechnical Design Criteria, River Docks Projects A, B, and C, Sacramento, California. Dated June 6, 1997
Kleinfelder, 2013. “Problem Identification Report, Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, and Beach Lake Levee),” Dated August 21, 2013.

Kleinfelder, 2016. “ULDC Geotechnical Results Summary, Sacramento River East Levee Downstream of American River, SAFCA FEMA Levee Accreditation (North Area Streams, American River, Sacramento River Downstream of American River, and Beach Lake Levee),” Dated April 29, 2016. 24001006.001A/SAC24R176178 Page 56 of 57 April 17, 2025 © 2025 Kleinfelder
Kleinfelder, 2021. “Final – Revision 1, Supplemental Geotechnical Analysis Memorandum Contract 3 Reaches, American River Common Features 2016, Sacramento River East Levee, Contract 3.” Dated September 10, 2021.

Kleinfelder, 2022. “Geotechnical Data Report, American River Common Features 2016, Sacramento River East Levee, Contracts 3 and 4, Sacramento County, California, Contract No.: W91238-16D-0019, Task Order W91238-20-F-0080, USACE Project No.: 456852.” Issue Date May 24, 2021. Revised October 14, 2022.

Kleinfelder, 2023. “Supplemental Geotechnical Analysis Memorandum Contract 4 Reaches, American River Common Features 2016, Sacramento River East Levee, Contract 4, Sacramento County, California, Contract No.: W91238-16D-0019, Task Order W91238-20-F-0080, USACE Project No.:
456852” Dated January 26, 2023
Kleinfelder, 2025. “Seismic Performance Summary Report, American River South Levee System, ULDC & FEMA Levee Certification Project, Sacramento Area Flood Control Agency Levee Systems, Sacramento County, California.” Dated April 16, 2025.

Kleinfelder Stantec Joint Venture, 2022. “Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder-Stantec Joint Venture for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.” Dated October 31, 2021.

MBK Engineers, 2025. “Technical Memorandum: American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee.” Dated April 9, 2025.

Mead & Hunt, 2025. “American River South Levee System Due Diligence Review for ULDC & FEMA Certification, Sacramento Area Levee Certification, Phase 3, Sacramento Area Flood Control Agency (SAFCA), Project Number R1941500-120265.09.” Dated April 15, 2025.

Maloney Odin Joint Venture, 2024. “Final As-Built, Dated 03/29/2024, Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 3. Solicitation No.:

W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder-Stantec Joint Venture for the United States Army Corps of Engineers, Sacramento District. Original Issue Date:
21 October 2021.” Dated March 29, 2024.
24001006.001A/SAC24R176178 Page 57 of 57 April 17, 2025 © 2025 Kleinfelder
Maloney Odin, A Joint Venture, 2024. As-Builts, Submittal 01 78 00-4 (Received November 25, 2024), Sacramento, California, American River Common Features 2016, Sacramento River East Levee, Contract 4. Solicitation No.: W91238-23-B-0002. Contract No.: W91238-23-C-0004. Prepared by Kleinfelder-Stantec Joint Venture for the United States Army Corps of Engineers, Sacramento District. Issue Date: 31 October 2022.

United States of America. Title 44 of the Code of Federal Regulations (44 CFR) Section 65.10 URS, 2009. “Phase 1 Geotechnical Data Report (P1GDR), Sacramento River Study Area, Urban Levee Geotechnical Evaluations Program.” Prepared for Department of Water Resources by URS.

Dated January 2009.

URS, 2014. “Geotechnical Evaluations Report, Volume 1, Existing Conditions, Sacramento River Study Area, Urban Levee Evaluations Project.” Prepared for Department of Water Resources by URS.

Dated July 24, 2014.

URS, 2015. “Geotechnical Evaluations Report, Volume 2, Remedial Alternatives, Sacramento River Study Area, Urban Levee Evaluations Project.” Prepared for Department of Water Resources by URS.

Dated February 4, 2015.

USACE, 1995. “Office Report, Structural and Geotechnical Evaluation of the Sacramento Riverwall.” Prepared by Soil and Structural Design Sections, U.S. Army Engineers District, Sacramento Corps of Engineers, Dated May 1995.

USACE, 2000. “Design and Construction of Levees,” US Army Corps of Engineers, Engineer Manual, EM 1110-2-1913, April 30, 2000.

USACE, 2005. “Design Guidance for Levee Underseepage,” US Army Corps of Engineers, Technical Letter ETL 1110-2-569, May 1, 2005.

USACE, 2022. “CESPK-EDG, SOP 3 Geotechnical Levee Practice, May 2022, Standard Operating Procedure 3, Geotechnical Levee Practice, US Army Corps of Engineers, Sacramento District, Geotechnical Engineering Branch.” Dated May 2022.

USACE, 2022. “Flood Walls and Other Hydraulic Retaining Walls.” US Army Corps of Engineers, Technical Letter EM 1110-2-2502, August 1, 2022.

USACE, 2025. “Design, Construction, and Maintenance of Relief Wells.” US Army Corps of Engineers, Technical Letter EM 1110-2-1914, March 7, 2025

FIGURES
______________________________________________________________________________________________

LIST OF ATTACHMENTS
Figure 1 American River South Levee System Site Vicinity Map Figure 2a American River South Levee System Site Location Map (Part 1 of 2) Figure 2b American River South Levee System Site Location Map (Part 2 of 2) PROJECT:

FILE NAME:

FIGURE
1 DRAWN:

CHECKED BY:

The information included on this graphic representation has been compiled from a variety of sources and is subject to change without notice. Kleinfelder makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness, or rights to the use of such information. This document is not intended for use as a land survey product nor is it designed or intended as a construction design document. The use or misuse of the information contained on this graphic representation is at the sole risk of the party using or misusing the information.

DRAWN BY:
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AMERICAN RIVER SOUTH LEVEE SYSTEM

SITE VICINITY MAP

AMERICAN RIVER SOUTH LEVEE SYSTEM

SEISMIC PERFORMANCE SUMMARY REPORT

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SAFCA LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
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REACHNAME
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AMERICAN RIVER SOUTH LEVEE SYSTEM

LOCATION MAP
(PART 1 OF 2)

AMERICAN RIVER SOUTH LEVEE SYSTEM

SEISMIC PERFORMANCE SUMMARY REPORT

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SAFCA LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
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REACHNAME
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AMERICAN RIVER SOUTH LEVEE SYSTEM

SEISMIC PERFORMANCE SUMMARY REPORT

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SAFCA LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA

AMERICAN RIVER SOUTH LEVEE SYSTEM

LOCATION MAP
(PART 2 OF 2)
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APPENDIX A
___________________________________________________________________________________

LIST OF ATTACHMENTS
MBK Engineers, 2025. “Technical Memorandum: American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee.” Dated April 9, 2025.

Water Resources Flood Control Water Rights

TECHNICAL MEMORANDUM
DATE: April 9, 2025
PREPARED FOR: SAFCA
PREPARED BY: Don Trieu, P.E. SUBJECT: American River South Levee System - Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 2 2 Acronyms and Abbreviations
1-D one dimensional
2-D two dimensional
AEP annual exceedance probability
ARS American River South
cfs cubic feet per second
CVFED Central Valley Floodplain Evaluation and Delineation CVFPP Central Valley Flood Protection Plan
CVHS Central Valley Hydrology Study
DWR California Department of Water Resources
DWSE Design Water Surface Elevation
FEMA Federal Emergency Management Agency
HTOL Hydraulic Top of Levee
LAR Lower American River
MBK MBK Engineers
MTOL Minimum Top of Levee
NAS North Area Streams
NAVD88 North American Vertical Datum of 1988
NEMDC Natomas East Main Drainage Canal
RM River Mile
SAFCA Sacramento Area Flood Control Agency
SNRR Sacramento Northern Railroad
SVRP Seismic Vulnerability Restoration Profile
ULDC Urban Levee Design Criteria
ULOP Urban Level of Flood Protection
UPRR Union Pacific Railroad
USACE U.S. Army Corps of Engineers
WSE water surface elevation

1. Purpose
The Sacramento Area Flood Control Agency (SAFCA) is in the process of evaluating the levees within its jurisdictional boundaries for compliance with the State of California’s Urban Levee Design Criteria (ULDC) (DWR, 2012). This technical memorandum provides documentation of the determination of the hydraulic parameters listed in Table 1, which are necessary for the ULDC compliance evaluation of the American River South (ARS) levee system.

All elevations are referenced to the North American Vertical Datum of 1988 (NAVD88).

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 3 Table 1. ULDC Hydraulic Parameters
Parameter ULDC Definition
ULDC 7.1 Design Water Surface Elevation (DWSE) Median 200-year (1/200 annual exceedance probability (AEP)) water surface elevation (WSE)
ULDC 7.2 Minimum Top of Levee (MTOL)
DWSE plus the higher of
• 3 feet, or
• wind setup and wave runup
Hydraulic Top of Levee (HTOL) to support ULDC

7.4, 7.5, 7.12, and 7.13
The lower of
• DWSE plus 3 feet, or
• Median 500-year (1/500 AEP) WSE
Seismic Vulnerability Restoration Profile (SVRP) to
support ULDC 7.7
10-year (1/10 AEP) water surface elevation plus the higher of • 3 feet, or
• wind setup and wave runup

2. Study Area
The American River South (ARS) levee system protects the floodplain bounded on the north by the American River, on the west by the Sacramento River, on the south by Morrison Creek, and on the east by high ground (see Figure 1). The ULDC profiles for the Morrison Creek north levee, also referred to as the Beach Lake north levee, are covered in a separate report (MBK, 2024). The levee segments in the ARS levee system covered in this report are summarized in Table 2. Levee stationing for the American River South Levee is shown in Figure 2. Levee stationing for the north end of the Sacramento River East Levee is shown in Figure 2, with the remainder shown in Figure 3.

It should be noted that for the American River South Levee, the reach of levee between stations 1555+50 and 1591+40 was removed from the system by the completion in 2009 of the Mayhew Drain closure structure, shown in Figure 4.

Table 2. American River South Levee System
Levee Segment Length (feet) Upstream Limit Downstream Limit American River South Levee 60,000 High ground near Gristmill Recreation Area
Sacramento River East Levee
Sacramento River East Levee 77,000 American River South Levee Beach Lake north levee SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 4 Figure 1. American River South Levee System.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 5 Figure 2. Levee Stationing for the American River South Levee and North End of Sacramento River East Levee.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 6 Figure 3. Levee Stationing for the South Portion of the Sacramento River East Levee.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 7 Figure 4. Mayhew Drain Closure Structure.

3. Hydrology
Central Valley Hydrology Study (CVHS) procedures and hydrologic data were used in this analysis. The CVHS was commissioned by DWR and prepared by the USACE (USACE, 2015). For the Sacramento River and San Joaquin River basins, the CVHS defines a procedure in which a scaled flood event with a pattern based on a historical flood event is selected to represent the flood of a specific frequency at a specific location, or centering. A CVHS event selection for a flood with a joint centering of the American River at Fair Oaks and Sacramento River at latitude of Sacramento developed by USACE (USACE, 2019) was used for the determination of the ARS ULDC profiles. The joint centering required USACE to adjust the coincident flow on the Sacramento River to match the annual chance exceedance associated with the primary flow on the American River (USACE, 2019). The CVHS flood events for the three flood frequencies needed for the ULDC profiles are summarized in Table 3.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 8 Table 3. CVHS Flood Events For American River at Fair Oaks and Sacramento River at Latitude of Sacramento Joint Flood Centering
Flood
Frequency
(AEP)
CVHS Flood Event
Peak Flow (cfs)
American River below
Folsom Dam
Sacramento River below
American River
1/10 1986-55% with 40% on American River 74,300 94,900
1/200 1986-110% with 125% on American River 116,900 107,500 1/500 1986-100% with 176% on American River 298,500 123,800

4. Hydraulic Model
Two HEC-RAS1 hydraulic models were used to determine the ULDC water surface elevations for the American River South Levee System:

1. Lower American River (LAR) model

2. Sacramento River system model
The LAR model was used for the determination of the ULDC profiles for the American River South Levee.

The Sacramento River system model was used for the determination of the ULDC profiles for the Sacramento River East Levee, and simulated with the each of the flood frequency and centering shown in Table 3 to determine the stage hydrograph boundary condition at the mouth of the American River for the LAR model simulations.

4.1. Lower American River (LAR) Model
The LAR model is a 1-D model consisting of the American River from Nimbus Dam (Lake Natoma) to the Sacramento River, and the NEMDC from Arcade Creek to the Sacramento River. It was adapted by MBK from the Sacramento River Watershed HEC-RAS model developed for the DWR Central Valley Floodplain Evaluation and Delineation (CVFED) project (Wood Rodgers, 2015). MBK parsed out the Lower American River from the CVFED model and ported it into HEC-RAS v6.4.1. Minor refinements to the model geometry were made to refine cross section location, top of levee elevations and bridge geometry. These refinements warranted a re-calibration of the hydraulic model A schematic of the LAR model is provided in Figure 5.
1 HEC-RAS is software developed by the USACE Hydrologic Engineering Center for the purpose of performing one-dimensional (1-D) and two-dimensional (2-D) hydraulic calculations for a full network of natural and constructed channels (USACE, 2023).

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 9 Figure 5. Lower American River HEC-RAS Model Schematic
The LAR model was calibrated using the January 1997 flood event, which had a peak American River flow of about 117,000 cfs (~1/200 AEP). On February 10, 2017, when the flow in the lower American River was about 85,000 cfs (~1/20 AEP), cbec Eco-engineering surveyed the water surface elevation at several locations. A simulation of the February 10, 2017, conditions was made to verify the model calibration. The results of the calibration and verification simulations are provided in Appendix A.

The LAR model was used to compute the ULDC WSE’s for the American River South Levee.

4.2. Sacramento River System Model
The Sacramento River System model is a combined 1-D and 2-D model of the Sacramento River and major tributaries and distributaries from Colusa at the upstream end to Suisun Bay at the downstream end. The model was developed by MBK from the Sacramento River Watershed HEC-RAS model developed for the DWR CVFED program (Wood Rodgers, 2015). MBK used the CVFED model as a foundation for the MBK HEC-RAS model. The MBK model geometry was refined to add 2-D flows areas then ported to HECRAS v6.4.1. These model geometry refinements and porting to HEC-RAS v6.4.1 required re-calibration of the MBK HEC-RAS model.

A schematic of the model is provided in Figure 6.The model is primarily made up of 1-D elements, supplemented with 2-D flow areas for the Fremont Weir area (Figure 7) and the Southport Levee Improved Project area on the Sacramento River about 2.5 miles south of the American River (Figure 8). 2- D flow areas were added at these two locations as they are areas of complex hydraulic flow patterns which are better simulated using a 2-D computation scheme.

The model was recalibrated using the December 2005 – January 2006 flood event (~1/10 AEP) and verified with the January 1997 flood event. Comparisons of observed and computed stages and flows in the ARS Sacramento River East Levee reach are provided in Appendix B.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 10 Figure 6. Sacramento River System HEC-RAS Model Schematic.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 11

5. Urban Levee Design Criteria (ULDC)
Section 7.1 of the ULDC allows for two options for the determination of the DWSE. The first option is the Federal Emergency Management Agency (FEMA) Approach, in which the DWSE is computed deterministically with a hydraulic model. The second option is the U.S. Army Corps of Engineers Approach, which incorporates uncertainty into the determination of the DWSE. The approach selected for this analysis was the FEMA Approach, due to its application and results being more straightforward and economical.

The ULDC defines the DWSE as the “200-year stage or water level used to design a levee or floodwall”.

Section 7.1.1 of the ULDC specifies that the hydraulic modeling used to determine the DWSE must consider the following:
• Upstream, downstream, and nearby levees and floodwalls protecting urban areas are assumed to be raised to the median 200-year water surface elevation plus 3 feet and not allowed to breach, even if overtopped. Overtopping flows are assumed to leave the channel and remain in the 200- year floodplain.

Figure 7. Fremont Weir 2-D flow area Figure 8. Southport 2-D flow area SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 12 • All project levees and floodwalls are to be modeled to incorporate a minimum crown elevation equal to the authorized (usually the 1955/1957) USACE design profiles – this affects nonurbanized areas for the most part – all such levees and floodwalls are to be allowed to overtop, act as weirs, and not breach for floods up to and including the median 500-year flood.

Overtopping flows are assumed to leave the channel and remain in the 200-year floodplain. • Non-project levees and floodwalls in non-urbanized areas in the region, to the extent they may affect the DWSE, are to be modeled at their existing or authorized height, whichever is higher, and to act as weirs without breaching if overtopped.
• Debris loading on bridges must be considered. Bridges with less than 3 feet of clearance above the DWSE may experience extraordinary debris loading that must be evaluated in addition to typical pier/bent debris loading. The evaluation should include historic and potential debris transport in the stream, an analysis of loading on the bridge, and analysis of backwater impacts on the DWSE in the vicinity of the bridge.

Section 7.1.3 of the ULDC requires adjustments to the DWSE for the effects of superelevation, when applicable. Superelevation is a tilting of the water surface, which may occur as water flows through a bend in the channel. Computational methods for determining superelevation adjustments are in the USACE Engineering Manual 1110-2-1601.

Section 7.1.3 of the ULDC also states that the “…the civil engineer should consider increasing the DWSE to account for the potential increases in water surface associated with climate change, updated hydrology, updated hydraulic models, and sea level rise”. This statement implies that adjustment for sea level rise is optional; however, Section 7.19 of the ULDC states, “the effects of sea level rise are to be estimated and addressed for the duration during which a Finding that the urban level of flood protection exists may be valid”. Based on the second statement, sea level rise adjustment appears to be mandatory.

Additionally, Section 7.1.3 of the ULDC states:
“[T]he civil engineer also needs to address two other situations: (1) whether upstream levee or floodwall breaches could produce overland flows that would reach the area protected by the levee system or increase the water surface elevation along the levee system, and (2) whether flooding in a nearby leveed area could fill that area and breach a nearby levee or floodwall, returning flow to the stream and increasing the DWSE for a portion of the levee system".

Neither of these conditions are applicable to the study area, and therefore were not evaluated.

The following sections address the requirements in the ULDC and discuss the application of each requirement for the American River South Levee System.

5.1 Levees
As per the ULDC, all urban levees were assumed to have a minimum top elevation of the median 200-year water surface elevation plus 3 feet. All non-urban State-Federal Project levees were assumed to have a minimum crown elevation equal to the authorized USACE design profiles.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 13

5.2 Debris Loading
The ULDC specifies that debris loading on bridges must be considered, and that “bridges with less than 3 feet of clearance above the DWSE may experience extraordinary debris loading that must be evaluated in addition to typical pier/bent debris loading”.

Bridge pier debris are applied in accordance with guidelines provided in a July 2014 letter (USACE, 2014), sent by USACE to the California Central Valley Flood Protection Board in order to clarify the level of screening and analysis that should be included on encroachment permit applications that are sent to the USACE for review. A copy of the letter is provided in Appendix C. Included in the letter was guidance for modeling debris build-up. Based on this guidance, under the ULDC “typical” debris loading condition, the hydraulic analysis included floating debris with a width equal to double the pier width, and a depth of 2 feet below the water surface. Under the ULDC “extraordinary” debris loading condition, floating debris with a depth of 2 feet below the water surface were modeled for the full width with the “extraordinary” condition.

Debris were not applied to bridges in the model upstream of the levee reaches, as debris on these bridges would have no effect on the water surface elevation in the levee reaches.

A summary of the bridge pier debris conditions included in the hydraulic analysis is provided in Table 4.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 14 Table 4. Bridge Pier Debris Loading
River Levee
Station Bridge
Debris Loading Condition1
200-yr 500-yr
American River 2 Bike Trail bridge t E
1467+80 Watt Ave t E
1386+60 Howe Ave t E
1347+10 Guy West t E
1320+30 H St t E
1204+00 Cap City Fwy t t
1195+20 RR t E
1118+10 RR t E
1111+90 Bike Trail t E
1100+60 CA-160 E t mix
1099+20 CA-160 W t mix
1013+00 I-5 t mix
1010+00 Jibboom St mix E
Sacramento River 1039+00 I St E E
1060+50 Tower Bridge t E
1103+20 US 50 t t
1215+30 Freeport t E
3 Paintersville t t
3 Walnut Grove t E
3 Isleton t mix
3 Rio Vista t t
Steamboat Slough 3 CA-160 t E
Sutter Slough 3 South River Rd E E
Miner Slough 3 CA-84 t t
Geogiana Slough 3Isleton Rd E E
3 Tyler Island t t
Threemile Slough 3 CA-160 t E
1 t = typical; E = extraordinary; mix = combination of t and E. 2 Upstream of American River South Levee.
3 Downstream of Sacramento River East Levee.

5.3 Superelevation
Superelevation is a tilting of the water surface that occurs on the outside of a river bend. The ULDC notes that, “on the outside of a bend, the superelevation needs to be added to the DWSE”. The superelevation adjustment, per USACE Engineer Manual 1110-2-1416, River Hydraulics, is specific to 1-D hydraulic modeling. Superelevation adjustments were applied at three locations on the American River South Levee and at one location on the Sacramento River East Levee (Figure 9):
• American River, levee station 1340+00 to 1362+00
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 15 • American River, levee station 1250+00 to 1257+00
• American River, levee station 1125+00 to 1150+00
• Sacramento River, levee station 1660+00 to 1680+00
As recommended in the ULDC, computational methods in USACE Engineering Manual 1110-2-1601 were used to compute superelevation. Superelevation is computed with the following equation:
y = CV2W/gr
where
y = superelevation (feet)
C = coefficient = 0.5 (tranquil, or subcritical, flow)
V = mean channel velocity (feet/second)
W = channel width at elevation of center-line water surface (feet) g = acceleration of gravity (32.2 feet/second2)
r = radius of channel center-line curvature (feet)
Figure 9. Superelevation Evaluation Locations
The computed superelevation and corresponding parameters are summarized in Table 5.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 16 Table 5. Superelevation
Location
r
(feet)
1/200 AEP 1/500 AEP
V
(feet/
second)
W
(feet)
Superelevation
(feet)
V
(feet/
second)
W
(feet)
Superelevation
(feet)
American River,
levee station 1362+00
to 1340+00
1700 10.6–11.4 251-262 0.26–0.31 13.8–15.0 251-262 0.45-0.53 American River,
levee station 1257+00
to 1250+00
800 8.8 259 0.39 10.1 259 0.51
American River,
levee station 1150+00
to 1125+00
2,300 5.9-6.8 335-448 0.11 7.3-8.4 335-448 0.16
Sacramento River,
levee station 1660+00
to 1680+00
2,300 4.5 649 0.09 4.9 649 0.11

5.4 Climate Change
The effects of climate change on extreme precipitation events in the Central Valley are being studied, but there is no indication of what the outcome of that work will be. Therefore, the hydrology used in this analysis has not been adjusted for the effects of climate change.

5.5 Updated Hydrology
This analysis makes use of the most recent accepted hydrologic data for the Study Area, which was developed as part of the Central Valley Hydrology Study, as noted in Section 4 of this report.

5.6 Updated Hydraulic Model
The hydraulic model used for this analysis was developed from the most current available data. Due to the calibration process, an updated hydraulic model would not be expected to have a substantial effect on the computed results unless significant physical changes have occurred in the modeled system. Since no significant physical changes have occurred since the data used for the model development was collected, no adjustment to the DWSE for updated hydraulic model has been included.

5.7 Sea Level Rise
The ULDC notes that, “the effects of sea level rise are to be estimated and addressed for the duration during which a Finding that the urban level of flood protection exists may be valid”. The duration of finding proposed for the subject project is 20 years.

The analysis assumed a sea level rise of 3.68 feet at the San Francisco Golden Gate which translates to approximately 2.5 feet rise at the downstream boundary conditions of the Sacramento River System model. This is the 50-year sea level rise projection determined by DWR for the 2022 update of the Central Valley Flood Protection Plan (CVFPP) (DWR, 2022). Being that the duration of the Urban Level of Protection finding is 20 years with periodic reviews every 5 years, the use of a 50-year projection is a conservative assumption. The effects of this sea level rise were applied at the downstream boundaries of SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 17 the Sacramento River systemwide hydraulic model simulations, which were used to determine the downstream boundary conditions for the LAR model.

6. Computed ULDC Hydraulic Parameters
The following sections present the computed ULDC hydraulic parameters that were described in Section 1 of this technical memorandum:
• Design Water Surface Elevation (DWSE)
• Minimum Top of Levee (MTOL)
• Hydraulic Top of Levee (HTOL)
• Seismic Vulnerability Restoration Profile

6.1 Design Water Surface Elevation (DWSE)
The ULDC defines the DWSE as “[the] median 200-year water surface elevation”, with adjustments for the following factors:
• Bridge pier debris loading
• Superelevation
• Sea level rise
Debris loading and sea level rise are accounted for in the hydraulic model simulations, as described in Sections 5.2 and 5.7. As noted in Section 5.3, the superelevation adjustment was applied at three locations on the American River South Levee and one location on the Sacramento River East Levee.

Figures 10 and 11 show profile plots of the computed DWSE for the American River South Levee and the Sacramento River East Levee, respectively. Levee crest profiles are included on the profile plots.

Tabulations of the DWSE profiles are provided in Appendix D.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 18 Figure 10. ULDC DWSE Profile, American River South Levee Figure 11. ULDC DWSE Profile, Sacramento River East Levee I Street bridge Tower Bridge Pioneer Memorial Bridge Sutterville Rd.

Freeport Bridge
Beach Lake Levee
20 25
30 35
40 45
1000+00 1100+00 1200+00 1300+00 1400+00 1500+00 1600+00 1700+00 1800+00 Elevation (feet, NAVD88)
Levee Station (feet)
Top of Levee [1]

ULDC DWSE
[1] Source: Psomas survey, 2024-2025
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 19

6.2 Minimum Top of Levee (MTOL)
The ULDC defines the MTOL as the higher of the DWSE plus 3 feet, or the DWSE plus the computed wind setup and wave runup. Wind setup and wave runup (wind and wave) for the ARS levee system has been computed by Mead & Hunt (Mead & Hunt, 2024). The maximum computed wind and wave is less than 3.0 feet for all the American River South Levee, and for the Sacramento River East Levee upstream of station 1654+00. Maximum wind and wave was computed to be 3.5 feet at station 1660+00 of the Sacramento River East Levee, and 3.1 feet at about station 1710+00. The wind and wave was applied to the MTOL by tapering from 3.0 feet at station 1654+00 to 3.5 feet at station 1660+00, then tapering back down to 3.1 feet at station 1710+00, and continuing with 3.1 feet to the end of the Sacramento River East Levee at station 1770+00. Figures 12 and 13 show profile plots of the MTOL for the American River South Levee and the Sacramento River East Levee, respectively. Tabulations of the MTOL profiles are provided in Appendix D.

Figure 12. ULDC MTOL Profile, American River South Levee SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 20 Figure 13. ULDC MTOL Profile, Sacramento River East Levee

6.3. Hydraulic Top of Levee (HTOL)
The ULDC defines the HTOL as the lower of the DWSE plus 3 feet, or the median 500-year WSE. Figures 14 and 15 show profile plots of the HTOL for the American River South Levee and the Sacramento River East Levee, respectively. For reference, the DWSE plus 3 feet and 500-year WSE profiles are also shown.

Tabulations of the HTOL profiles are provided in Appendix D.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 21 Figure 14. ULDC HTOL Profile, American River South Levee Figure 15. ULDC HTOL Profile, Sacramento River East Levee I Street bridge Tower Bridge Pioneer Memorial Bridge Sutterville Rd.

Freeport BridgeBeach Lake Levee
20 25
30 35
40 45
1000+00 1100+00 1200+00 1300+00 1400+00 1500+00 1600+00 1700+00 1800+00 Elevation (feet, NAVD88)
Levee Station (feet)
Top of Levee [1]
DWSE + 3 feet
500-year WSE

ULDC HTOL
[1] Source: Psomas survey, 2024-2025
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 22

6.4 Seismic Vulnerability Restoration Profile (SVRP)
The ULDC specifies that if there is the potential for levee damage due to a seismic event, a plan needs to be in place to “restore grade and dimensions for at least 10-year WSE plus 3 feet of freeboard or higher for wind setup and wave runup within 8 weeks”. This profile is referred to herein as the Seismic Vulnerability Restoration Profile (SVRP). As described in Section 6.2, the wind setup and wave runup exceeded 3 feet on the Sacramento River East Levee downstream of station 1654+00. Seismic vulnerability restoration profiles for the American River South Levee and Sacramento River East Levee are provided in Figures 16 and 17, respectively. Tabulations of the seismic vulnerability restoration profiles are provided in Appendix D.

Figure 16. ULDC SVRP Profile, American River South Levee SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 23 Figure 17. ULDC SVRP Profile, Sacramento River East Levee I Street bridge Tower Bridge Pioneer Memorial Bridge
Sutterville Rd.

Freeport BridgeBeach Lake Levee
20 25
30 35
40 45
1000+00 1100+00 1200+00 1300+00 1400+00 1500+00 1600+00 1700+00 1800+00 Elevation (feet, NAVD88)
Levee Station (feet)
Top of Levee [1]

ULDC SVRP
[1] Source: Psomas survey, 2024-2025
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page 24 References
DWR. (2012). Urban Levee Design Criteria. May 2012.

DWR. (2022). 2022 CVFPP Update - Technical Analyses Summary Report. November 2022.

MBK. (2024). Beach Lake North Levee – Determination of the Urban Levee Design Criteria Design Water Surface Elevation, Minimum Top of Levee, and Hydraulic Top of Levee - DRAFT.

December 13, 2024.

Mead & Hunt. (2024). Wind-Wave Analysis for American River South and Sacramento River East Levee Systems. December 5, 2024.

USACE. (2014). Letter from US Army Corps of Engineers, Sacramento District, to Central Valley Flood Protection Board. July 21, 2014.

USACE. (2015). Central Valley Hydrology Study. November 29, 2015.

USACE. (2019). Memorandum for Record, Subject: CVHS Hydrograph Package for HEC-RAS Model Inputs. February 20, 2019.

USACE. (2020). Hydrology Technical Memorandum for Developing WRDA 2016 Water Surface Profiles.

April 10, 2020.

USACE. (2023). HEC-RAS User's Manual. Retrieved from
https://www.hec.usace.army.mil/confluence/rasdocs/rasum/6.4 Wood Rodgers. (2015). Refine/Calibrate Combined Sacramento River and San Joaquin River Systems, Sacramento River System Study Area Report. May 29, 2015.

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL

APPENDIX A
Hydraulic Model Calibration
Lower American River Model
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page A-1 Simulation Event Peak American River flow
Calibration January 1997 flow 117,000 cfs
Verification February 10, 2017 ~85,000 cfs
Figure A-1. Calibration, January 1997, Maximum Water Surface Elevation Profile with Surveyed High Water Marks, American River river miles 10 to 23 (Mayhew Drain to Nimbus Dam) Figure A-2. Calibration, January 1997, Maximum Water Surface Elevation Profile with Surveyed High Water Marks, American River river miles 0 to 11 (Sacramento River to Mayhew Drain) Figure A-3. Verification, February 10, 2017, Maximum Water Surface Elevation Profile with Surveyed Water Surface Elevation, American River river miles 10 to 23 (Mayhew Drain to Nimbus Dam)
Figure A-4. Verification, February 10, 2017, Maximum Water Surface Elevation Profile with Surveyed Water Surface Elevation, American River river miles 0 to 11 (Sacramento River to Mayhew Drain)

SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page A-2 Figure A-1. Calibration, January 1997, Maximum Water Surface Elevation Profile with Surveyed High Water Marks, American River, river miles 10 to 23 (Mayhew Drain to Nimbus Dam) Figure A-2. Calibration, January 1997, Maximum Water Surface Elevation Profile with Surveyed High Water Marks, American River, river miles 0 to 11 (Sacramento River to Mayhew Drain) SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page A-3 Figure A-3. Verification, February 10, 2017, Maximum Water Surface Elevation Profile with Surveyed Water Surface Elevations, American River, river miles 10 to 23 (Mayhew Drain to Nimbus Dam) Figure A-4. Verification, February 10, 2017, Maximum Water Surface Elevation Profile with Surveyed Water Surface Elevations, American River, river miles 0 to 11 (Sacramento River to Mayhew Drain) SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL

APPENDIX B
Hydraulic Model Calibration and Verification
Sacramento River System Model
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page B-1 Observed data in the ARS Sacramento River reach is available at the two stream gages shown in Figure B1. A summary comparison of the observed and computed calibration event peak stages and flows at the gages is provided in Table B-1. Additionally, several high-water marks from the calibration event and verification event were identified in the levee reach and surveyed by MBK Engineers (January 1997 flood event) and the California Department of Water Resources (Dec-Jan 2006 flood event). A profile plot comparing the computed maximum water surface elevation along the ARS Sacramento River East Levee and the surveyed high-water marks and measured gage peaks is provided in Figure B-2 and Figure B-3.

Questionable high-water marks such at RM 45.2 (Figure B-2) were not considered in the calibration and verification as it is 3.5 feet higher than the recorded peak stage but shown on the plot for disclosure of all data received.

Table B-1. Stream Gages with Observed Data Available for Calibration and Verification Dec-Jan. 2006 Flood January 1997 Flood
Gage Parameter Observed Computed Difference Observed Computed Difference Sacramento
River at I
Street
(DWR
A02100)
Peak Stage
(feet,
NAVD88)

30.07 30.01 -0.06 ft 32.92 32.90 -0.02 ft
Sacramento
River at
Freeport
(USGS
11447650)
Peak Stage
(feet,
NAVD88)

23.30 23.38 +0.08 ft 25.99 26.01 +0.02 ft
Peak Flow
(cfs) 97,200 94,950 -2.3% 115,000 108,645 -5.5%
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page B-2 Figure B-1. Stream Gage Location Map
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page B-3 Figure B-2. Calibration Analysis Maximum Water Surface Elevation Profile, ARS Sacramento River East Levee Reach
Figure B-3. Verification Analysis Maximum Water Surface Elevation Profile, ARS Sacramento River East Levee Reach
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Appendix C
Bridge Debris Loading Guidance
SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-1 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-2 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-3 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-4 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-5 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-6 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-7 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-8 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page C-9 SAFCA April 9, 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL

APPENDIX D

ULDC Hydraulic Parameter Profile Tabulations

Acronyms
DWSE design water surface elevation
MTOL minimum top of levee
HTOL hydraulic top of levee
SVRP seismic vulnerability restoration profile
Table D-1 American River South Levee
Table D-2 Sacramento River East Levee
SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-1 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1000+00 33.40 36.40 36.40 33.42 1052+00 34.55 37.55 37.55 34.12 1001+00 33.44 36.44 36.44 33.45 1053+00 34.56 37.56 37.56 34.13 1002+00 33.47 36.47 36.47 33.49 1054+00 34.58 37.58 37.58 34.14 1003+00 33.51 36.51 36.51 33.52 1055+00 34.60 37.60 37.60 34.14 1004+00 33.54 36.54 36.54 33.55 1056+00 34.62 37.62 37.62 34.15 1005+00 33.54 36.54 36.54 33.55 1057+00 34.64 37.64 37.64 34.16 1006+00 33.54 36.54 36.54 33.55 1058+00 34.65 37.65 37.65 34.17 1007+00 33.54 36.54 36.54 33.55 1059+00 34.67 37.67 37.67 34.18 1008+00 33.54 36.54 36.54 33.55 1060+00 34.69 37.69 37.69 34.19 1009+00 33.54 36.54 36.54 33.56 1061+00 34.71 37.71 37.71 34.19 1010+00 33.56 36.56 36.56 33.57 1062+00 34.73 37.73 37.73 34.21 1011+00 33.61 36.61 36.61 33.60 1063+00 34.77 37.77 37.77 34.22 1012+00 33.67 36.67 36.67 33.63 1064+00 34.80 37.80 37.80 34.24 1013+00 33.72 36.72 36.72 33.66 1065+00 34.84 37.84 37.84 34.26 1014+00 33.73 36.73 36.73 33.66 1066+00 34.87 37.87 37.87 34.28 1015+00 33.73 36.73 36.73 33.66 1067+00 34.91 37.91 37.91 34.30 1016+00 33.76 36.76 36.76 33.68 1068+00 34.94 37.94 37.94 34.32 1017+00 33.80 36.80 36.80 33.70 1069+00 34.98 37.98 37.98 34.34 1018+00 33.84 36.84 36.84 33.73 1070+00 35.01 38.01 38.01 34.36 1019+00 33.87 36.87 36.87 33.75 1071+00 35.05 38.05 38.05 34.38 1020+00 33.91 36.91 36.91 33.76 1072+00 35.07 38.07 38.07 34.40 1021+00 33.94 36.94 36.94 33.78 1073+00 35.10 38.10 38.10 34.41 1022+00 33.97 36.97 36.97 33.80 1074+00 35.12 38.12 38.12 34.42 1023+00 34.00 37.00 37.00 33.81 1075+00 35.14 38.14 38.14 34.44 1024+00 34.01 37.01 37.01 33.82 1076+00 35.17 38.17 38.17 34.45 1025+00 34.01 37.01 37.01 33.83 1077+00 35.19 38.19 38.19 34.46 1026+00 34.01 37.01 37.01 33.83 1078+00 35.22 38.22 38.22 34.48 1027+00 34.02 37.02 37.02 33.84 1079+00 35.24 38.24 38.24 34.49 1028+00 34.05 37.05 37.05 33.85 1080+00 35.26 38.26 38.26 34.51 1029+00 34.08 37.08 37.08 33.87 1081+00 35.28 38.28 38.28 34.52 1030+00 34.10 37.10 37.10 33.88 1082+00 35.29 38.29 38.29 34.52 1031+00 34.13 37.13 37.13 33.89 1083+00 35.29 38.29 38.29 34.52 1032+00 34.16 37.16 37.16 33.91 1084+00 35.30 38.30 38.30 34.52 1033+00 34.18 37.18 37.18 33.92 1085+00 35.34 38.34 38.34 34.54 1034+00 34.21 37.21 37.21 33.93 1086+00 35.36 38.36 38.36 34.54 1035+00 34.23 37.23 37.23 33.94 1087+00 35.40 38.40 38.40 34.56 1036+00 34.25 37.25 37.25 33.95 1088+00 35.50 38.50 38.50 34.63 1037+00 34.27 37.27 37.27 33.97 1089+00 35.52 38.52 38.52 34.64 1038+00 34.29 37.29 37.29 33.98 1090+00 35.53 38.53 38.53 34.64 1039+00 34.31 37.31 37.31 33.99 1091+00 35.54 38.54 38.54 34.65 1040+00 34.34 37.34 37.34 34.00 1092+00 35.55 38.55 38.55 34.66 1041+00 34.36 37.36 37.36 34.01 1093+00 35.57 38.57 38.57 34.67 1042+00 34.38 37.38 37.38 34.03 1094+00 35.58 38.58 38.58 34.68 1043+00 34.40 37.40 37.40 34.04 1095+00 35.59 38.59 38.59 34.68 1044+00 34.43 37.43 37.43 34.05 1096+00 35.61 38.61 38.61 34.69 1045+00 34.45 37.45 37.45 34.06 1097+00 35.60 38.60 38.60 34.69 1046+00 34.47 37.47 37.47 34.07 1098+00 35.59 38.59 38.59 34.68 1047+00 34.48 37.48 37.48 34.08 1099+00 35.91 38.91 38.91 34.87 1048+00 34.49 37.49 37.49 34.09 1100+00 36.01 39.01 39.01 34.94 1049+00 34.51 37.51 37.51 34.10 1101+00 36.12 39.12 39.12 35.02 1050+00 34.52 37.52 37.52 34.10 1102+00 36.12 39.12 39.12 35.02 1051+00 34.53 37.53 37.53 34.11 1103+00 36.14 39.14 39.14 35.04

SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-2 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1104+00 36.17 39.17 39.17 35.05 1156+00 37.07 40.07 40.07 35.56 1105+00 36.19 39.19 39.19 35.07 1157+00 37.07 40.07 40.07 35.57 1106+00 36.21 39.21 39.21 35.09 1158+00 37.07 40.07 40.07 35.58 1107+00 36.23 39.23 39.23 35.10 1159+00 37.07 40.07 40.07 35.58 1108+00 36.25 39.25 39.25 35.12 1160+00 37.07 40.07 40.07 35.59 1109+00 36.27 39.27 39.27 35.13 1161+00 37.07 40.07 40.07 35.60 1110+00 36.29 39.29 39.29 35.15 1162+00 37.07 40.07 40.07 35.61 1111+00 36.29 39.29 39.29 35.14 1163+00 37.09 40.09 40.09 35.62 1112+00 36.29 39.29 39.29 35.12 1164+00 37.10 40.10 40.10 35.63 1113+00 36.36 39.36 39.36 35.17 1165+00 37.11 40.11 40.11 35.64 1114+00 36.36 39.36 39.36 35.17 1166+00 37.13 40.13 40.13 35.65 1115+00 36.36 39.36 39.36 35.17 1167+00 37.14 40.14 40.14 35.66 1116+00 36.36 39.36 39.36 35.17 1168+00 37.15 40.15 40.15 35.67 1117+00 36.30 39.30 39.30 35.13 1169+00 37.17 40.17 40.17 35.68 1118+00 36.15 39.15 39.15 35.01 1170+00 37.18 40.18 40.18 35.69 1119+00 36.21 39.21 39.21 35.04 1171+00 37.19 40.19 40.19 35.70 1120+00 36.33 39.33 39.33 35.13 1172+00 37.21 40.21 40.21 35.71 1121+00 36.36 39.36 39.36 35.14 1173+00 37.23 40.23 40.23 35.73 1122+00 36.38 39.38 39.38 35.16 1174+00 37.24 40.24 40.24 35.74 1123+00 36.41 39.41 39.41 35.17 1175+00 37.26 40.26 40.26 35.76 1124+00 36.44 39.44 39.44 35.18 1176+00 37.28 40.28 40.28 35.77 1125+00 36.46 39.46 39.46 35.20 1177+00 37.30 40.30 40.30 35.78 1126+00 36.49 39.49 39.49 35.21 1178+00 37.31 40.31 40.31 35.80 1127+00 36.52 39.52 39.52 35.23 1179+00 37.33 40.33 40.33 35.81 1128+00 36.55 39.55 39.55 35.24 1180+00 37.35 40.35 40.35 35.82 1129+00 36.57 39.57 39.57 35.25 1181+00 37.36 40.36 40.36 35.84 1130+00 36.60 39.60 39.60 35.26 1182+00 37.37 40.37 40.37 35.84 1131+00 36.62 39.62 39.62 35.27 1183+00 37.37 40.37 40.37 35.85 1132+00 36.65 39.65 39.65 35.28 1184+00 37.38 40.38 40.38 35.85 1133+00 36.68 39.68 39.68 35.29 1185+00 37.38 40.38 40.38 35.86 1134+00 36.70 39.70 39.70 35.30 1186+00 37.39 40.39 40.39 35.86 1135+00 36.73 39.73 39.73 35.31 1187+00 37.41 40.41 40.41 35.88 1136+00 36.76 39.76 39.76 35.32 1188+00 37.47 40.47 40.47 35.92 1137+00 36.78 39.78 39.78 35.33 1189+00 37.52 40.52 40.52 35.96 1138+00 36.81 39.81 39.81 35.34 1190+00 37.58 40.58 40.58 36.00 1139+00 36.84 39.84 39.84 35.35 1191+00 37.64 40.64 40.64 36.04 1140+00 36.85 39.85 39.85 35.37 1192+00 37.69 40.69 40.69 36.08 1141+00 36.87 39.87 39.87 35.38 1193+00 37.75 40.75 40.75 36.12 1142+00 36.89 39.89 39.89 35.40 1194+00 37.77 40.77 40.77 36.15 1143+00 36.91 39.91 39.91 35.41 1195+00 37.75 40.75 40.75 36.14 1144+00 36.93 39.93 39.93 35.42 1196+00 37.90 40.90 40.90 36.26 1145+00 36.95 39.95 39.95 35.44 1197+00 37.92 40.92 40.92 36.26 1146+00 36.97 39.97 39.97 35.45 1198+00 37.93 40.93 40.93 36.27 1147+00 36.99 39.99 39.99 35.47 1199+00 37.95 40.95 40.95 36.27 1148+00 37.01 40.01 40.01 35.48 1200+00 37.97 40.97 40.97 36.28 1149+00 37.03 40.03 40.03 35.49 1201+00 37.98 40.98 40.98 36.28 1150+00 37.04 40.04 40.04 35.51 1202+00 38.00 41.00 41.00 36.29 1151+00 37.06 40.06 40.06 35.52 1203+00 38.01 41.01 41.01 36.29 1152+00 37.07 40.07 40.07 35.53 1204+00 38.08 41.08 41.08 36.35 1153+00 37.07 40.07 40.07 35.54 1205+00 38.12 41.12 41.12 36.34 1154+00 37.07 40.07 40.07 35.55 1206+00 38.15 41.15 41.15 36.36 1155+00 37.07 40.07 40.07 35.55 1207+00 38.18 41.18 41.18 36.39

SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-3 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1208+00 38.22 41.22 41.22 36.42 1260+00 39.88 42.88 42.88 37.80 1209+00 38.25 41.25 41.25 36.44 1261+00 39.92 42.92 42.92 37.85 1210+00 38.27 41.27 41.27 36.46 1262+00 39.96 42.96 42.96 37.89 1211+00 38.30 41.30 41.30 36.48 1263+00 40.01 43.01 43.01 37.94 1212+00 38.33 41.33 41.33 36.49 1264+00 40.05 43.05 43.05 37.99 1213+00 38.36 41.36 41.36 36.51 1265+00 40.09 43.09 43.09 38.03 1214+00 38.38 41.38 41.38 36.53 1266+00 40.13 43.13 43.13 38.08 1215+00 38.41 41.41 41.41 36.55 1267+00 40.17 43.17 43.17 38.11 1216+00 38.44 41.44 41.44 36.56 1268+00 40.21 43.21 43.21 38.13 1217+00 38.46 41.46 41.46 36.58 1269+00 40.25 43.25 43.25 38.16 1218+00 38.46 41.46 41.46 36.58 1270+00 40.29 43.29 43.29 38.18 1219+00 38.46 41.46 41.46 36.57 1271+00 40.35 43.35 43.35 38.22 1220+00 38.47 41.47 41.47 36.57 1272+00 40.45 43.45 43.45 38.31 1221+00 38.47 41.47 41.47 36.57 1273+00 40.55 43.55 43.55 38.40 1222+00 38.47 41.47 41.47 36.56 1274+00 40.64 43.64 43.64 38.49 1223+00 38.47 41.47 41.47 36.56 1275+00 40.74 43.74 43.74 38.57 1224+00 38.47 41.47 41.47 36.56 1276+00 40.81 43.81 43.81 38.63 1225+00 38.48 41.48 41.48 36.55 1277+00 40.87 43.87 43.87 38.69 1226+00 38.48 41.48 41.48 36.55 1278+00 40.93 43.93 43.93 38.75 1227+00 38.48 41.48 41.48 36.55 1279+00 41.00 44.00 44.00 38.81 1228+00 38.50 41.50 41.50 36.57 1280+00 41.05 44.05 44.05 38.86 1229+00 38.57 41.57 41.57 36.62 1281+00 41.09 44.09 44.09 38.90 1230+00 38.63 41.63 41.63 36.68 1282+00 41.13 44.13 44.13 38.94 1231+00 38.69 41.69 41.69 36.74 1283+00 41.17 44.17 44.17 38.98 1232+00 38.76 41.76 41.76 36.80 1284+00 41.21 44.21 44.21 39.02 1233+00 38.82 41.82 41.82 36.86 1285+00 41.26 44.26 44.26 39.07 1234+00 38.88 41.88 41.88 36.91 1286+00 41.23 44.23 44.23 39.05 1235+00 38.94 41.94 41.94 36.97 1287+00 41.17 44.17 44.17 39.02 1236+00 39.01 42.01 42.01 37.03 1288+00 41.12 44.12 44.12 38.98 1237+00 39.07 42.07 42.07 37.09 1289+00 41.07 44.07 44.07 38.95 1238+00 39.14 42.14 42.14 37.13 1290+00 41.01 44.01 44.01 38.91 1239+00 39.23 42.23 42.23 37.15 1291+00 40.96 43.96 43.96 38.88 1240+00 39.31 42.31 42.31 37.18 1292+00 41.05 44.05 44.05 38.97 1241+00 39.40 42.40 42.40 37.20 1293+00 41.26 44.26 44.26 39.16 1242+00 39.48 42.48 42.48 37.22 1294+00 41.47 44.47 44.47 39.35 1243+00 39.56 42.56 42.56 37.24 1295+00 41.60 44.60 44.60 39.47 1244+00 39.65 42.65 42.65 37.26 1296+00 41.69 44.69 44.69 39.52 1245+00 39.69 42.69 42.69 37.28 1297+00 41.78 44.78 44.78 39.58 1246+00 39.69 42.69 42.69 37.31 1298+00 41.86 44.86 44.86 39.64 1247+00 39.69 42.69 42.69 37.34 1299+00 41.95 44.95 44.95 39.70 1248+00 39.69 42.69 42.69 37.37 1300+00 42.04 45.04 45.04 39.78 1249+00 39.69 42.69 42.69 37.40 1301+00 42.14 45.14 45.14 39.86 1250+00 39.69 42.69 42.69 37.43 1302+00 42.23 45.23 45.23 39.94 1251+00 39.69 42.69 42.69 37.46 1303+00 42.33 45.33 45.33 40.02 1252+00 39.68 42.68 42.68 37.48 1304+00 42.42 45.42 45.42 40.10 1253+00 39.68 42.68 42.68 37.51 1305+00 42.48 45.48 45.48 40.14 1254+00 39.68 42.68 42.68 37.54 1306+00 42.49 45.49 45.49 40.16 1255+00 39.68 42.68 42.68 37.57 1307+00 42.50 45.50 45.50 40.18 1256+00 39.71 42.71 42.71 37.61 1308+00 42.51 45.51 45.51 40.20 1257+00 39.75 42.75 42.75 37.66 1309+00 42.53 45.53 45.53 40.22 1258+00 39.80 42.80 42.80 37.71 1310+00 42.54 45.54 45.54 40.24 1259+00 39.84 42.84 42.84 37.75 1311+00 42.57 45.57 45.57 40.29 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-4 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1312+00 42.60 45.60 45.60 40.34 1364+00 45.40 48.40 48.40 42.45 1313+00 42.63 45.63 45.63 40.39 1365+00 45.61 48.61 48.61 42.62 1314+00 42.65 45.65 45.65 40.44 1366+00 45.66 48.66 48.66 42.66 1315+00 42.70 45.70 45.70 40.49 1367+00 45.71 48.71 48.71 42.70 1316+00 42.76 45.76 45.76 40.55 1368+00 45.75 48.75 48.75 42.74 1317+00 42.82 45.82 45.82 40.61 1369+00 45.80 48.80 48.80 42.77 1318+00 42.87 45.87 45.87 40.67 1370+00 45.82 48.82 48.82 42.79 1319+00 42.93 45.93 45.93 40.73 1371+00 45.84 48.84 48.84 42.80 1320+00 42.77 45.77 45.77 40.66 1372+00 45.85 48.85 48.85 42.81 1321+00 42.91 45.91 45.91 40.74 1373+00 45.87 48.87 48.87 42.82 1322+00 43.05 46.05 46.05 40.83 1374+00 45.88 48.88 48.88 42.83 1323+00 43.19 46.19 46.19 40.91 1375+00 45.89 48.89 48.89 42.84 1324+00 43.32 46.32 46.32 41.00 1376+00 45.91 48.91 48.91 42.85 1325+00 43.46 46.46 46.46 41.09 1377+00 45.92 48.92 48.92 42.86 1326+00 43.50 46.50 46.50 41.12 1378+00 45.94 48.94 48.94 42.87 1327+00 43.55 46.55 46.55 41.16 1379+00 45.95 48.95 48.95 42.88 1328+00 43.59 46.59 46.59 41.19 1380+00 45.96 48.96 48.96 42.89 1329+00 43.64 46.64 46.64 41.23 1381+00 45.98 48.98 48.98 42.90 1330+00 43.68 46.68 46.68 41.26 1382+00 46.03 49.03 49.03 42.95 1331+00 43.67 46.67 46.67 41.25 1383+00 46.10 49.10 49.10 43.00 1332+00 43.65 46.65 46.65 41.24 1384+00 46.16 49.16 49.16 43.05 1333+00 43.64 46.64 46.64 41.23 1385+00 46.23 49.23 49.23 43.10 1334+00 43.62 46.62 46.62 41.22 1386+00 46.30 49.30 49.30 43.16 1335+00 43.60 46.60 46.60 41.20 1387+00 46.37 49.37 49.37 43.21 1336+00 43.67 46.67 46.67 41.21 1388+00 46.32 49.32 49.32 43.16 1337+00 43.74 46.74 46.74 41.23 1389+00 46.33 49.33 49.33 43.18 1338+00 43.82 46.82 46.82 41.24 1390+00 46.37 49.37 49.37 43.22 1339+00 43.90 46.90 46.90 41.26 1391+00 46.42 49.42 49.42 43.27 1340+00 43.98 46.98 46.98 41.27 1392+00 46.46 49.46 49.46 43.32 1341+00 44.06 47.06 47.06 41.29 1393+00 46.50 49.50 49.50 43.36 1342+00 44.11 47.11 47.11 41.32 1394+00 46.57 49.57 49.57 43.42 1343+00 44.17 47.17 47.17 41.35 1395+00 46.66 49.66 49.66 43.48 1344+00 44.23 47.23 47.23 41.38 1396+00 46.74 49.74 49.74 43.54 1345+00 44.28 47.28 47.28 41.41 1397+00 46.82 49.82 49.82 43.60 1346+00 44.34 47.34 47.34 41.45 1398+00 46.91 49.91 49.91 43.66 1347+00 44.62 47.62 47.62 41.67 1399+00 46.95 49.95 49.95 43.70 1348+00 44.67 47.67 47.67 41.71 1400+00 46.98 49.98 49.98 43.73 1349+00 44.73 47.73 47.73 41.75 1401+00 47.01 50.01 50.01 43.76 1350+00 44.78 47.78 47.78 41.79 1402+00 47.04 50.04 50.04 43.79 1351+00 44.84 47.84 47.84 41.83 1403+00 47.07 50.07 50.07 43.82 1352+00 44.89 47.89 47.89 41.87 1404+00 47.11 50.11 50.11 43.85 1353+00 44.95 47.95 47.95 41.91 1405+00 47.14 50.14 50.14 43.88 1354+00 45.01 48.01 48.01 41.95 1406+00 47.18 50.18 50.18 43.91 1355+00 45.06 48.06 48.06 41.99 1407+00 47.22 50.22 50.22 43.94 1356+00 45.12 48.12 48.12 42.03 1408+00 47.26 50.26 50.26 43.97 1357+00 45.16 48.16 48.16 42.08 1409+00 47.30 50.30 50.30 44.00 1358+00 45.19 48.19 48.19 42.15 1410+00 47.33 50.33 50.33 44.02 1359+00 45.22 48.22 48.22 42.22 1411+00 47.33 50.33 50.33 44.03 1360+00 45.24 48.24 48.24 42.29 1412+00 47.34 50.34 50.34 44.03 1361+00 45.26 48.26 48.26 42.36 1413+00 47.34 50.34 50.34 44.04 1362+00 45.16 48.16 48.16 42.27 1414+00 47.35 50.35 50.35 44.04 1363+00 45.26 48.26 48.26 42.34 1415+00 47.36 50.36 50.36 44.05 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-5 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1416+00 47.35 50.35 50.35 44.05 1468+00 48.45 51.45 51.45 45.07 1417+00 47.34 50.34 50.34 44.04 1469+00 48.57 51.57 51.57 45.16 1418+00 47.34 50.34 50.34 44.04 1470+00 48.62 51.62 51.62 45.18 1419+00 47.33 50.33 50.33 44.03 1471+00 48.71 51.71 51.71 45.26 1420+00 47.32 50.32 50.32 44.03 1472+00 48.79 51.79 51.79 45.34 1421+00 47.31 50.31 50.31 44.02 1473+00 48.88 51.88 51.88 45.41 1422+00 47.31 50.31 50.31 44.03 1474+00 48.96 51.96 51.96 45.49 1423+00 47.33 50.33 50.33 44.04 1475+00 49.04 52.04 52.04 45.56 1424+00 47.35 50.35 50.35 44.06 1476+00 49.13 52.13 52.13 45.64 1425+00 47.36 50.36 50.36 44.07 1477+00 49.21 52.21 52.21 45.72 1426+00 47.37 50.37 50.37 44.08 1478+00 49.29 52.29 52.29 45.79 1427+00 47.37 50.37 50.37 44.08 1479+00 49.34 52.34 52.34 45.84 1428+00 47.37 50.37 50.37 44.08 1480+00 49.39 52.39 52.39 45.90 1429+00 47.37 50.37 50.37 44.09 1481+00 49.44 52.44 52.44 45.95 1430+00 47.38 50.38 50.38 44.09 1482+00 49.49 52.49 52.49 46.00 1431+00 47.41 50.41 50.41 44.12 1483+00 49.54 52.54 52.54 46.06 1432+00 47.45 50.45 50.45 44.15 1484+00 49.59 52.59 52.59 46.11 1433+00 47.48 50.48 50.48 44.18 1485+00 49.63 52.63 52.63 46.16 1434+00 47.51 50.51 50.51 44.21 1486+00 49.68 52.68 52.68 46.22 1435+00 47.52 50.52 50.52 44.22 1487+00 49.73 52.73 52.73 46.27 1436+00 47.50 50.50 50.50 44.20 1488+00 49.83 52.83 52.83 46.35 1437+00 47.47 50.47 50.47 44.18 1489+00 49.93 52.93 52.93 46.43 1438+00 47.44 50.44 50.44 44.16 1490+00 50.03 53.03 53.03 46.52 1439+00 47.42 50.42 50.42 44.15 1491+00 50.13 53.13 53.13 46.60 1440+00 47.46 50.46 50.46 44.19 1492+00 50.23 53.23 53.23 46.68 1441+00 47.53 50.53 50.53 44.24 1493+00 50.26 53.26 53.26 46.71 1442+00 47.59 50.59 50.59 44.30 1494+00 50.30 53.30 53.30 46.74 1443+00 47.66 50.66 50.66 44.35 1495+00 50.34 53.34 53.34 46.76 1444+00 47.72 50.72 50.72 44.41 1496+00 50.37 53.37 53.37 46.79 1445+00 47.78 50.78 50.78 44.46 1497+00 50.40 53.40 53.40 46.82 1446+00 47.84 50.84 50.84 44.51 1498+00 50.42 53.42 53.42 46.86 1447+00 47.90 50.90 50.90 44.56 1499+00 50.43 53.43 53.43 46.90 1448+00 47.96 50.96 50.96 44.61 1500+00 50.45 53.45 53.45 46.94 1449+00 48.02 51.02 51.02 44.66 1501+00 50.46 53.46 53.46 46.98 1450+00 48.10 51.10 51.10 44.72 1502+00 50.52 53.52 53.52 47.04 1451+00 48.18 51.18 51.18 44.78 1503+00 50.58 53.58 53.58 47.10 1452+00 48.25 51.25 51.25 44.84 1504+00 50.65 53.65 53.65 47.16 1453+00 48.33 51.33 51.33 44.90 1505+00 50.71 53.71 53.71 47.23 1454+00 48.40 51.40 51.40 44.96 1506+00 50.77 53.77 53.77 47.28 1455+00 48.48 51.48 51.48 45.01 1507+00 50.82 53.82 53.82 47.33 1456+00 48.55 51.55 51.55 45.07 1508+00 50.88 53.88 53.88 47.39 1457+00 48.63 51.63 51.63 45.13 1509+00 50.93 53.93 53.93 47.44 1458+00 48.70 51.70 51.70 45.19 1510+00 50.98 53.98 53.98 47.49 1459+00 48.69 51.69 51.69 45.19 1511+00 51.04 54.04 54.04 47.54 1460+00 48.66 51.66 51.66 45.17 1512+00 51.08 54.08 54.08 47.57 1461+00 48.63 51.63 51.63 45.15 1513+00 51.13 54.13 54.13 47.61 1462+00 48.60 51.60 51.60 45.14 1514+00 51.18 54.18 54.18 47.65 1463+00 48.57 51.57 51.57 45.12 1515+00 51.23 54.23 54.23 47.68 1464+00 48.54 51.54 51.54 45.10 1516+00 51.28 54.28 54.28 47.72 1465+00 48.50 51.50 51.50 45.08 1517+00 51.36 54.36 54.36 47.77 1466+00 48.47 51.47 51.47 45.07 1518+00 51.43 54.43 54.43 47.82 1467+00 48.44 51.44 51.44 45.05 1519+00 51.50 54.50 54.50 47.87 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-6 Table D-1. ULDC Hydraulic Parameter Profiles, American River South Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1520+00 51.57 54.57 54.57 47.92 1607+00 53.05 56.05 56.05 49.18 1521+00 51.70 54.70 54.70 48.02 1608+00 53.04 56.04 56.04 49.18 1522+00 51.84 54.84 54.84 48.12 1609+00 53.03 56.03 56.03 49.17 1523+00 51.97 54.97 54.97 48.22 1610+00 53.02 56.02 56.02 49.17 1524+00 52.10 55.10 55.10 48.32 1611+00 53.02 56.02 56.02 49.16 1525+00 52.14 55.14 55.14 48.35 1612+00 53.01 56.01 56.01 49.16 1526+00 52.15 55.15 55.15 48.35 1613+00 53.00 56.00 56.00 49.16 1527+00 52.15 55.15 55.15 48.35 1614+00 52.99 55.99 55.99 49.16 1528+00 52.18 55.18 55.18 48.38 1615+00 52.99 55.99 55.99 49.16 1529+00 52.23 55.23 55.23 48.42 1616+00 52.99 55.99 55.99 49.16 1530+00 52.27 55.27 55.27 48.45 1617+00 52.99 55.99 55.99 49.16 1531+00 52.31 55.31 55.31 48.49 1618+00 52.98 55.98 55.98 49.16 1532+00 52.35 55.35 55.35 48.53 1619+00 52.98 55.98 55.98 49.16 1533+00 52.39 55.39 55.39 48.56 1620+00 52.98 55.98 55.98 49.16 1534+00 52.44 55.44 55.44 48.60 1621+00 52.98 55.98 55.98 49.16 1535+00 52.48 55.48 55.48 48.63 1622+00 52.98 55.98 55.98 49.17 1536+00 52.52 55.52 55.52 48.67 1623+00 52.98 55.98 55.98 49.17 1537+00 52.56 55.56 55.56 48.71 1624+00 52.99 55.99 55.99 49.18 1538+00 52.58 55.58 55.58 48.73 1625+00 53.00 56.00 56.00 49.19 1539+00 52.60 55.60 55.60 48.75 1626+00 53.02 56.02 56.02 49.21 1540+00 52.62 55.62 55.62 48.76 1627+00 53.03 56.03 56.03 49.22 1541+00 52.64 55.64 55.64 48.78 1628+00 53.04 56.04 56.04 49.23 1542+00 52.66 55.66 55.66 48.80 1629+00 53.06 56.06 56.06 49.24 1543+00 52.68 55.68 55.68 48.81 1630+00 53.07 56.07 56.07 49.26 1544+00 52.69 55.69 55.69 48.83 1631+00 53.08 56.08 56.08 49.27 1545+00 52.71 55.71 55.71 48.85 1632+00 53.10 56.10 56.10 49.28 1546+00 52.73 55.73 55.73 48.86 1633+00 53.12 56.12 56.12 49.29 1547+00 52.74 55.74 55.74 48.88 1634+00 53.14 56.14 56.14 49.30 1548+00 52.76 55.76 55.76 48.90 1635+00 53.17 56.17 56.17 49.30 1549+00 52.78 55.78 55.78 48.91 1635+50 53.18 56.18 56.18 49.31 1550+00 52.80 55.80 55.80 48.93
1551+00 52.81 55.81 55.81 48.94
1552+00 52.81 55.81 55.81 48.94
1553+00 52.82 55.82 55.82 48.95
1554+00 52.82 55.82 55.82 48.95
1555+00 52.83 55.83 55.83 48.96
Mayhew Drain closure structure
1592+00 53.00 56.00 56.00 49.13
1593+00 53.01 56.01 56.01 49.13
1594+00 53.01 56.01 56.01 49.14
1595+00 53.02 56.02 56.02 49.14
1596+00 53.02 56.02 56.02 49.15
1597+00 53.03 56.03 56.03 49.15
1598+00 53.03 56.03 56.03 49.15
1599+00 53.04 56.04 56.04 49.16
1600+00 53.04 56.04 56.04 49.16
1601+00 53.05 56.05 56.05 49.17
1602+00 53.05 56.05 56.05 49.17
1603+00 53.06 56.06 56.06 49.18
1604+00 53.06 56.06 56.06 49.18
1605+00 53.07 56.07 56.07 49.19
1606+00 53.06 56.06 56.06 49.18

SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-7 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1000+00 33.40 36.40 36.40 33.42 1052+00 32.50 35.50 35.50 32.69 1001+00 33.39 36.39 36.39 33.41 1053+00 32.50 35.50 35.50 32.69 1002+00 33.38 36.38 36.38 33.40 1054+00 32.49 35.49 35.49 32.69 1003+00 33.37 36.37 36.37 33.39 1055+00 32.49 35.49 35.49 32.68 1004+00 33.37 36.37 36.37 33.38 1056+00 32.48 35.48 35.48 32.67 1005+00 33.36 36.36 36.36 33.37 1057+00 32.47 35.47 35.47 32.66 1006+00 33.35 36.35 36.35 33.36 1058+00 32.46 35.46 35.46 32.65 1007+00 33.34 36.34 36.34 33.35 1059+00 32.45 35.45 35.45 32.64 1008+00 33.33 36.33 36.33 33.34 1060+00 32.44 35.44 35.44 32.63 1009+00 33.32 36.32 36.32 33.33 1061+00 32.38 35.38 35.38 32.58 1010+00 33.31 36.31 36.31 33.32 1062+00 32.43 35.43 35.43 32.62 1011+00 33.30 36.30 36.30 33.31 1063+00 32.42 35.42 35.42 32.61 1012+00 33.28 36.28 36.28 33.29 1064+00 32.41 35.41 35.41 32.61 1013+00 33.26 36.26 36.26 33.27 1065+00 32.40 35.40 35.40 32.60 1014+00 33.25 36.25 36.25 33.26 1066+00 32.40 35.40 35.40 32.59 1015+00 33.23 36.23 36.23 33.24 1067+00 32.39 35.39 35.39 32.58 1016+00 33.21 36.21 36.21 33.22 1068+00 32.38 35.38 35.38 32.57 1017+00 33.19 36.19 36.19 33.20 1069+00 32.37 35.37 35.37 32.57 1018+00 33.18 36.18 36.18 33.19 1070+00 32.36 35.36 35.36 32.55 1019+00 33.17 36.17 36.17 33.18 1071+00 32.35 35.35 35.35 32.54 1020+00 33.17 36.17 36.17 33.18 1072+00 32.34 35.34 35.34 32.53 1021+00 33.16 36.16 36.16 33.17 1073+00 32.33 35.33 35.33 32.52 1022+00 33.15 36.15 36.15 33.16 1074+00 32.31 35.31 35.31 32.51 1023+00 33.14 36.14 36.14 33.15 1075+00 32.30 35.30 35.30 32.50 1024+00 33.12 36.12 36.12 33.13 1076+00 32.29 35.29 35.29 32.49 1025+00 33.11 36.11 36.11 33.12 1077+00 32.28 35.28 35.28 32.47 1026+00 33.09 36.09 36.09 33.11 1078+00 32.27 35.27 35.27 32.46 1027+00 33.08 36.08 36.08 33.09 1079+00 32.26 35.26 35.26 32.45 1028+00 33.07 36.07 36.07 33.08 1080+00 32.25 35.25 35.24 32.44 1029+00 33.05 36.05 36.05 33.07 1081+00 32.24 35.24 35.24 32.43 1030+00 33.04 36.04 36.04 33.05 1082+00 32.23 35.23 35.23 32.42 1031+00 33.02 36.02 36.02 33.03 1083+00 32.22 35.22 35.22 32.41 1032+00 33.00 36.00 36.00 33.02 1084+00 32.21 35.21 35.21 32.40 1033+00 32.99 35.99 35.99 33.00 1085+00 32.20 35.20 35.20 32.39 1034+00 32.97 35.97 35.97 32.98 1086+00 32.19 35.19 35.19 32.38 1035+00 32.95 35.95 35.95 32.97 1087+00 32.18 35.18 35.18 32.37 1036+00 32.94 35.94 35.94 32.95 1088+00 32.17 35.17 35.17 32.36 1037+00 32.92 35.92 35.92 32.93 1089+00 32.16 35.16 35.16 32.35 1038+00 32.86 35.86 35.86 32.91 1090+00 32.16 35.16 35.15 32.34 1039+00 32.63 35.63 35.63 32.81 1091+00 32.15 35.15 35.14 32.33 1040+00 32.65 35.65 35.65 32.83 1092+00 32.14 35.14 35.13 32.32 1041+00 32.63 35.63 35.63 32.82 1093+00 32.13 35.13 35.12 32.32 1042+00 32.62 35.62 35.62 32.80 1094+00 32.12 35.12 35.11 32.31 1043+00 32.60 35.60 35.60 32.79 1095+00 32.11 35.11 35.10 32.30 1044+00 32.58 35.58 35.58 32.77 1096+00 32.10 35.10 35.09 32.29 1045+00 32.57 35.57 35.57 32.76 1097+00 32.08 35.08 35.07 32.27 1046+00 32.55 35.55 35.55 32.74 1098+00 32.07 35.07 35.06 32.26 1047+00 32.54 35.54 35.54 32.73 1099+00 32.05 35.05 35.04 32.24 1048+00 32.52 35.52 35.52 32.71 1100+00 32.04 35.04 35.02 32.23 1049+00 32.51 35.51 35.51 32.70 1101+00 32.02 35.02 35.00 32.21 1050+00 32.51 35.51 35.51 32.70 1102+00 32.01 35.01 34.99 32.20 1051+00 32.50 35.50 35.50 32.69 1103+00 32.01 35.01 34.99 32.20 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-8 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1104+00 32.02 35.02 35.00 32.21 1156+00 31.50 34.50 34.46 31.70 1105+00 32.02 35.02 35.00 32.20 1157+00 31.50 34.50 34.45 31.69 1106+00 32.01 35.01 35.00 32.20 1158+00 31.49 34.49 34.44 31.68 1107+00 32.01 35.01 35.00 32.20 1159+00 31.48 34.48 34.44 31.67 1108+00 32.01 35.01 35.00 32.19 1160+00 31.48 34.48 34.43 31.67 1109+00 32.00 35.00 34.99 32.19 1161+00 31.47 34.47 34.42 31.66 1110+00 31.99 34.99 34.97 32.17 1162+00 31.46 34.46 34.41 31.65 1111+00 31.97 34.97 34.96 32.16 1163+00 31.45 34.45 34.40 31.64 1112+00 31.96 34.96 34.94 32.14 1164+00 31.44 34.44 34.39 31.64 1113+00 31.94 34.94 34.93 32.13 1165+00 31.44 34.44 34.39 31.63 1114+00 31.93 34.93 34.91 32.11 1166+00 31.43 34.43 34.38 31.62 1115+00 31.91 34.91 34.90 32.10 1167+00 31.42 34.42 34.37 31.61 1116+00 31.90 34.90 34.88 32.09 1168+00 31.41 34.41 34.35 31.60 1117+00 31.89 34.89 34.87 32.07 1169+00 31.40 34.40 34.34 31.59 1118+00 31.87 34.87 34.85 32.06 1170+00 31.39 34.39 34.33 31.58 1119+00 31.86 34.86 34.83 32.04 1171+00 31.38 34.38 34.32 31.57 1120+00 31.84 34.84 34.82 32.03 1172+00 31.37 34.37 34.31 31.56 1121+00 31.83 34.83 34.80 32.01 1173+00 31.36 34.36 34.30 31.55 1122+00 31.81 34.81 34.78 32.00 1174+00 31.35 34.35 34.29 31.54 1123+00 31.80 34.80 34.77 31.98 1175+00 31.34 34.34 34.28 31.53 1124+00 31.78 34.78 34.75 31.97 1176+00 31.33 34.33 34.27 31.52 1125+00 31.76 34.76 34.73 31.95 1177+00 31.32 34.32 34.26 31.51 1126+00 31.75 34.75 34.72 31.94 1178+00 31.31 34.31 34.25 31.50 1127+00 31.73 34.73 34.70 31.92 1179+00 31.30 34.30 34.24 31.49 1128+00 31.73 34.73 34.70 31.92 1180+00 31.29 34.29 34.23 31.48 1129+00 31.72 34.72 34.69 31.91 1181+00 31.28 34.28 34.22 31.47 1130+00 31.71 34.71 34.67 31.90 1182+00 31.28 34.28 34.21 31.47 1131+00 31.70 34.70 34.66 31.89 1183+00 31.27 34.27 34.20 31.46 1132+00 31.69 34.69 34.65 31.88 1184+00 31.26 34.26 34.20 31.45 1133+00 31.68 34.68 34.64 31.87 1185+00 31.25 34.25 34.19 31.44 1134+00 31.67 34.67 34.63 31.86 1186+00 31.24 34.24 34.18 31.43 1135+00 31.66 34.66 34.62 31.85 1187+00 31.23 34.23 34.17 31.42 1136+00 31.65 34.65 34.61 31.84 1188+00 31.23 34.23 34.16 31.42 1137+00 31.64 34.64 34.60 31.83 1189+00 31.22 34.22 34.15 31.41 1138+00 31.63 34.63 34.59 31.82 1190+00 31.21 34.21 34.14 31.40 1139+00 31.63 34.63 34.58 31.81 1191+00 31.20 34.20 34.13 31.39 1140+00 31.62 34.62 34.58 31.81 1192+00 31.19 34.19 34.12 31.38 1141+00 31.62 34.62 34.57 31.80 1193+00 31.18 34.18 34.11 31.37 1142+00 31.61 34.61 34.57 31.80 1194+00 31.17 34.17 34.10 31.36 1143+00 31.60 34.60 34.56 31.79 1195+00 31.16 34.16 34.09 31.35 1144+00 31.60 34.60 34.56 31.79 1196+00 31.16 34.16 34.08 31.34 1145+00 31.59 34.59 34.55 31.78 1197+00 31.15 34.15 34.08 31.34 1146+00 31.58 34.58 34.54 31.77 1198+00 31.14 34.14 34.07 31.33 1147+00 31.57 34.57 34.53 31.76 1199+00 31.13 34.13 34.06 31.32 1148+00 31.56 34.56 34.52 31.75 1200+00 31.12 34.12 34.05 31.31 1149+00 31.55 34.55 34.51 31.74 1201+00 31.11 34.11 34.04 31.30 1150+00 31.55 34.55 34.50 31.73 1202+00 31.11 34.11 34.03 31.29 1151+00 31.54 34.54 34.50 31.73 1203+00 31.10 34.10 34.02 31.29 1152+00 31.53 34.53 34.49 31.72 1204+00 31.09 34.09 34.01 31.28 1153+00 31.53 34.53 34.48 31.72 1205+00 31.08 34.08 34.00 31.27 1154+00 31.52 34.52 34.47 31.71 1206+00 31.07 34.07 34.00 31.26 1155+00 31.51 34.51 34.47 31.70 1207+00 31.06 34.06 33.99 31.25 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-9 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1208+00 31.05 34.05 33.98 31.24 1260+00 30.57 33.57 33.46 30.76 1209+00 31.05 34.05 33.97 31.23 1261+00 30.56 33.56 33.45 30.75 1210+00 31.04 34.04 33.96 31.23 1262+00 30.55 33.55 33.44 30.74 1211+00 31.03 34.03 33.95 31.22 1263+00 30.54 33.54 33.43 30.73 1212+00 31.02 34.02 33.95 31.21 1264+00 30.53 33.53 33.42 30.72 1213+00 31.01 34.01 33.94 31.20 1265+00 30.52 33.52 33.41 30.72 1214+00 31.00 34.00 33.93 31.19 1266+00 30.52 33.52 33.41 30.71 1215+00 30.99 33.99 33.92 31.18 1267+00 30.51 33.51 33.40 30.70 1216+00 30.98 33.98 33.90 31.17 1268+00 30.50 33.50 33.39 30.69 1217+00 30.97 33.97 33.89 31.16 1269+00 30.49 33.49 33.38 30.69 1218+00 30.96 33.96 33.88 31.15 1270+00 30.49 33.49 33.37 30.68 1219+00 30.95 33.95 33.87 31.14 1271+00 30.48 33.48 33.36 30.67 1220+00 30.94 33.94 33.86 31.13 1272+00 30.47 33.47 33.36 30.66 1221+00 30.93 33.93 33.85 31.11 1273+00 30.46 33.46 33.35 30.66 1222+00 30.92 33.92 33.84 31.10 1274+00 30.46 33.46 33.34 30.65 1223+00 30.90 33.90 33.82 31.09 1275+00 30.45 33.45 33.33 30.64 1224+00 30.89 33.89 33.81 31.08 1276+00 30.44 33.44 33.32 30.63 1225+00 30.88 33.88 33.80 31.07 1277+00 30.43 33.43 33.32 30.63 1226+00 30.87 33.87 33.79 31.06 1278+00 30.43 33.43 33.31 30.62 1227+00 30.86 33.86 33.78 31.05 1279+00 30.42 33.42 33.30 30.61 1228+00 30.85 33.85 33.77 31.04 1280+00 30.41 33.41 33.29 30.61 1229+00 30.84 33.84 33.75 31.03 1281+00 30.41 33.41 33.29 30.60 1230+00 30.83 33.83 33.74 31.02 1282+00 30.40 33.40 33.28 30.60 1231+00 30.82 33.82 33.73 31.01 1283+00 30.40 33.40 33.27 30.59 1232+00 30.81 33.81 33.72 31.00 1284+00 30.39 33.39 33.27 30.59 1233+00 30.80 33.80 33.71 30.99 1285+00 30.39 33.39 33.26 30.58 1234+00 30.79 33.79 33.70 30.98 1286+00 30.38 33.38 33.26 30.58 1235+00 30.78 33.78 33.69 30.97 1287+00 30.38 33.38 33.25 30.57 1236+00 30.77 33.77 33.68 30.96 1288+00 30.37 33.37 33.24 30.57 1237+00 30.76 33.76 33.67 30.96 1289+00 30.36 33.36 33.24 30.56 1238+00 30.75 33.75 33.66 30.95 1290+00 30.36 33.36 33.23 30.55 1239+00 30.75 33.75 33.65 30.94 1291+00 30.35 33.35 33.22 30.55 1240+00 30.74 33.74 33.64 30.93 1292+00 30.34 33.34 33.21 30.54 1241+00 30.73 33.73 33.63 30.92 1293+00 30.34 33.34 33.21 30.53 1242+00 30.72 33.72 33.62 30.91 1294+00 30.33 33.33 33.20 30.53 1243+00 30.71 33.71 33.61 30.90 1295+00 30.32 33.32 33.19 30.52 1244+00 30.70 33.70 33.61 30.90 1296+00 30.32 33.32 33.19 30.51 1245+00 30.70 33.70 33.60 30.89 1297+00 30.31 33.31 33.18 30.51 1246+00 30.69 33.69 33.59 30.88 1298+00 30.30 33.30 33.17 30.50 1247+00 30.68 33.68 33.58 30.87 1299+00 30.30 33.30 33.16 30.49 1248+00 30.67 33.67 33.57 30.86 1300+00 30.29 33.29 33.15 30.48 1249+00 30.67 33.67 33.56 30.86 1301+00 30.28 33.28 33.14 30.48 1250+00 30.66 33.66 33.56 30.85 1302+00 30.27 33.27 33.13 30.47 1251+00 30.65 33.65 33.55 30.84 1303+00 30.26 33.26 33.12 30.46 1252+00 30.64 33.64 33.54 30.83 1304+00 30.25 33.25 33.11 30.45 1253+00 30.63 33.63 33.53 30.82 1305+00 30.24 33.24 33.10 30.44 1254+00 30.62 33.62 33.52 30.81 1306+00 30.24 33.24 33.09 30.43 1255+00 30.61 33.61 33.51 30.80 1307+00 30.23 33.23 33.08 30.42 1256+00 30.60 33.60 33.50 30.80 1308+00 30.22 33.22 33.07 30.42 1257+00 30.59 33.59 33.49 30.79 1309+00 30.21 33.21 33.06 30.41 1258+00 30.59 33.59 33.48 30.78 1310+00 30.20 33.20 33.05 30.40 1259+00 30.58 33.58 33.47 30.77 1311+00 30.19 33.19 33.04 30.39 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-10 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1312+00 30.18 33.18 33.03 30.38 1364+00 29.71 32.71 32.51 29.92 1313+00 30.17 33.17 33.02 30.37 1365+00 29.70 32.70 32.50 29.91 1314+00 30.16 33.16 33.01 30.36 1366+00 29.69 32.69 32.49 29.90 1315+00 30.15 33.15 33.00 30.35 1367+00 29.69 32.69 32.48 29.90 1316+00 30.14 33.14 32.99 30.34 1368+00 29.68 32.68 32.48 29.89 1317+00 30.13 33.13 32.98 30.33 1369+00 29.67 32.67 32.47 29.88 1318+00 30.13 33.13 32.97 30.32 1370+00 29.66 32.66 32.46 29.87 1319+00 30.12 33.12 32.96 30.31 1371+00 29.65 32.65 32.45 29.86 1320+00 30.11 33.11 32.95 30.30 1372+00 29.64 32.64 32.44 29.85 1321+00 30.10 33.10 32.94 30.30 1373+00 29.64 32.64 32.43 29.85 1322+00 30.09 33.09 32.94 30.29 1374+00 29.63 32.63 32.42 29.84 1323+00 30.08 33.08 32.93 30.28 1375+00 29.62 32.62 32.41 29.83 1324+00 30.08 33.08 32.92 30.28 1376+00 29.61 32.61 32.41 29.82 1325+00 30.07 33.07 32.92 30.27 1377+00 29.61 32.61 32.40 29.82 1326+00 30.07 33.07 32.91 30.27 1378+00 29.60 32.60 32.39 29.81 1327+00 30.06 33.06 32.90 30.26 1379+00 29.59 32.59 32.38 29.80 1328+00 30.05 33.05 32.89 30.25 1380+00 29.58 32.58 32.37 29.79 1329+00 30.05 33.05 32.89 30.25 1381+00 29.58 32.58 32.36 29.79 1330+00 30.04 33.04 32.88 30.24 1382+00 29.57 32.57 32.36 29.78 1331+00 30.03 33.03 32.87 30.23 1383+00 29.56 32.56 32.35 29.77 1332+00 30.02 33.02 32.86 30.23 1384+00 29.55 32.55 32.34 29.76 1333+00 30.02 33.02 32.85 30.22 1385+00 29.54 32.54 32.33 29.75 1334+00 30.01 33.01 32.84 30.21 1386+00 29.54 32.54 32.32 29.75 1335+00 30.00 33.00 32.83 30.20 1387+00 29.53 32.53 32.32 29.74 1336+00 29.99 32.99 32.82 30.19 1388+00 29.52 32.52 32.31 29.73 1337+00 29.98 32.98 32.81 30.18 1389+00 29.51 32.51 32.30 29.72 1338+00 29.97 32.97 32.80 30.17 1390+00 29.51 32.51 32.29 29.72 1339+00 29.96 32.96 32.78 30.16 1391+00 29.50 32.50 32.28 29.71 1340+00 29.95 32.95 32.77 30.15 1392+00 29.49 32.49 32.28 29.70 1341+00 29.94 32.94 32.76 30.14 1393+00 29.48 32.48 32.27 29.69 1342+00 29.93 32.93 32.75 30.13 1394+00 29.48 32.48 32.26 29.68 1343+00 29.92 32.92 32.74 30.12 1395+00 29.47 32.47 32.25 29.68 1344+00 29.91 32.91 32.73 30.11 1396+00 29.46 32.46 32.24 29.67 1345+00 29.90 32.90 32.72 30.10 1397+00 29.45 32.45 32.23 29.66 1346+00 29.89 32.89 32.71 30.09 1398+00 29.44 32.44 32.22 29.65 1347+00 29.88 32.88 32.69 30.08 1399+00 29.44 32.44 32.22 29.64 1348+00 29.87 32.87 32.68 30.07 1400+00 29.43 32.43 32.21 29.63 1349+00 29.86 32.86 32.67 30.06 1401+00 29.42 32.42 32.20 29.63 1350+00 29.84 32.84 32.66 30.05 1402+00 29.41 32.41 32.19 29.62 1351+00 29.83 32.83 32.65 30.04 1403+00 29.40 32.40 32.18 29.61 1352+00 29.82 32.82 32.64 30.03 1404+00 29.39 32.39 32.17 29.60 1353+00 29.81 32.81 32.63 30.02 1405+00 29.38 32.38 32.16 29.59 1354+00 29.80 32.80 32.62 30.01 1406+00 29.37 32.37 32.15 29.58 1355+00 29.79 32.79 32.60 30.00 1407+00 29.37 32.37 32.14 29.57 1356+00 29.78 32.78 32.59 29.99 1408+00 29.36 32.36 32.13 29.56 1357+00 29.78 32.78 32.58 29.98 1409+00 29.35 32.35 32.12 29.55 1358+00 29.77 32.77 32.57 29.98 1410+00 29.34 32.34 32.11 29.54 1359+00 29.76 32.76 32.56 29.97 1411+00 29.33 32.33 32.10 29.54 1360+00 29.75 32.75 32.55 29.96 1412+00 29.32 32.32 32.10 29.53 1361+00 29.74 32.74 32.54 29.95 1413+00 29.31 32.31 32.09 29.52 1362+00 29.73 32.73 32.53 29.94 1414+00 29.31 32.31 32.08 29.51 1363+00 29.72 32.72 32.52 29.93 1415+00 29.30 32.30 32.07 29.50 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-11 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1416+00 29.29 32.29 32.06 29.49 1468+00 28.79 31.79 31.51 29.00 1417+00 29.28 32.28 32.05 29.48 1469+00 28.78 31.78 31.51 29.00 1418+00 29.25 32.25 32.02 29.46 1470+00 28.78 31.78 31.50 28.99 1419+00 29.24 32.24 32.00 29.44 1471+00 28.77 31.77 31.49 28.99 1420+00 29.22 32.22 31.98 29.43 1472+00 28.77 31.77 31.49 28.98 1421+00 29.20 32.20 31.96 29.41 1473+00 28.76 31.76 31.48 28.97 1422+00 29.19 32.19 31.94 29.39 1474+00 28.75 31.75 31.47 28.97 1423+00 29.17 32.17 31.92 29.38 1475+00 28.74 31.74 31.45 28.95 1424+00 29.15 32.15 31.90 29.36 1476+00 28.71 31.71 31.43 28.93 1425+00 29.13 32.13 31.88 29.35 1477+00 28.69 31.69 31.40 28.91 1426+00 29.12 32.12 31.86 29.33 1478+00 28.67 31.67 31.37 28.89 1427+00 29.10 32.10 31.84 29.32 1479+00 28.64 31.64 31.34 28.86 1428+00 29.09 32.09 31.82 29.30 1480+00 28.62 31.62 31.32 28.84 1429+00 29.08 32.08 31.82 29.30 1481+00 28.60 31.60 31.29 28.82 1430+00 29.07 32.07 31.81 29.29 1482+00 28.57 31.57 31.26 28.80 1431+00 29.07 32.07 31.81 29.29 1483+00 28.55 31.55 31.23 28.78 1432+00 29.06 32.06 31.80 29.28 1484+00 28.55 31.55 31.23 28.77 1433+00 29.06 32.06 31.79 29.28 1485+00 28.55 31.55 31.24 28.77 1434+00 29.05 32.05 31.79 29.27 1486+00 28.55 31.55 31.24 28.78 1435+00 29.05 32.05 31.78 29.27 1487+00 28.55 31.55 31.24 28.78 1436+00 29.04 32.04 31.78 29.26 1488+00 28.56 31.56 31.25 28.78 1437+00 29.04 32.04 31.77 29.26 1489+00 28.56 31.56 31.25 28.78 1438+00 29.04 32.04 31.77 29.25 1490+00 28.56 31.56 31.25 28.78 1439+00 29.03 32.03 31.77 29.25 1491+00 28.56 31.56 31.26 28.78 1440+00 29.03 32.03 31.77 29.25 1492+00 28.57 31.57 31.26 28.79 1441+00 29.03 32.03 31.77 29.25 1493+00 28.57 31.57 31.26 28.79 1442+00 29.03 32.03 31.77 29.24 1494+00 28.57 31.57 31.26 28.79 1443+00 29.03 32.03 31.77 29.24 1495+00 28.57 31.57 31.26 28.78 1444+00 29.03 32.03 31.77 29.24 1496+00 28.56 31.56 31.26 28.78 1445+00 29.03 32.03 31.77 29.24 1497+00 28.56 31.56 31.26 28.78 1446+00 29.02 32.02 31.77 29.23 1498+00 28.56 31.56 31.26 28.78 1447+00 29.02 32.02 31.77 29.23 1499+00 28.56 31.56 31.26 28.77 1448+00 29.01 32.01 31.76 29.22 1500+00 28.56 31.56 31.26 28.77 1449+00 29.01 32.01 31.75 29.21 1501+00 28.56 31.56 31.26 28.77 1450+00 29.00 32.00 31.74 29.21 1502+00 28.56 31.56 31.26 28.77 1451+00 28.99 31.99 31.73 29.20 1503+00 28.55 31.55 31.26 28.76 1452+00 28.98 31.98 31.72 29.19 1504+00 28.55 31.55 31.25 28.76 1453+00 28.97 31.97 31.71 29.18 1505+00 28.54 31.54 31.24 28.75 1454+00 28.96 31.96 31.70 29.17 1506+00 28.54 31.54 31.24 28.74 1455+00 28.96 31.96 31.70 29.17 1507+00 28.53 31.53 31.23 28.74 1456+00 28.95 31.95 31.69 29.16 1508+00 28.52 31.52 31.22 28.73 1457+00 28.93 31.93 31.67 29.14 1509+00 28.52 31.52 31.22 28.72 1458+00 28.92 31.92 31.65 29.13 1510+00 28.51 31.51 31.21 28.71 1459+00 28.90 31.90 31.64 29.11 1511+00 28.50 31.50 31.20 28.71 1460+00 28.89 31.89 31.62 29.10 1512+00 28.50 31.50 31.20 28.70 1461+00 28.87 31.87 31.60 29.08 1513+00 28.49 31.49 31.19 28.69 1462+00 28.86 31.86 31.59 29.07 1514+00 28.48 31.48 31.18 28.69 1463+00 28.84 31.84 31.57 29.05 1515+00 28.48 31.48 31.18 28.68 1464+00 28.83 31.83 31.55 29.04 1516+00 28.47 31.47 31.17 28.67 1465+00 28.81 31.81 31.54 29.03 1517+00 28.47 31.47 31.17 28.67 1466+00 28.80 31.80 31.52 29.02 1518+00 28.46 31.46 31.16 28.66 1467+00 28.80 31.80 31.52 29.01 1519+00 28.45 31.45 31.16 28.65 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-12 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1520+00 28.45 31.45 31.15 28.65 1572+00 28.00 31.00 30.65 28.21 1521+00 28.44 31.44 31.14 28.64 1573+00 27.99 30.99 30.64 28.20 1522+00 28.44 31.44 31.14 28.64 1574+00 27.98 30.98 30.63 28.19 1523+00 28.43 31.43 31.13 28.63 1575+00 27.97 30.97 30.62 28.18 1524+00 28.42 31.42 31.12 28.62 1576+00 27.96 30.96 30.61 28.17 1525+00 28.42 31.42 31.12 28.61 1577+00 27.95 30.95 30.60 28.16 1526+00 28.41 31.41 31.11 28.61 1578+00 27.95 30.95 30.59 28.15 1527+00 28.40 31.40 31.10 28.60 1579+00 27.94 30.94 30.58 28.14 1528+00 28.39 31.39 31.09 28.59 1580+00 27.93 30.93 30.57 28.14 1529+00 28.39 31.39 31.08 28.58 1581+00 27.92 30.92 30.56 28.13 1530+00 28.38 31.38 31.08 28.58 1582+00 27.91 30.91 30.54 28.12 1531+00 28.37 31.37 31.07 28.57 1583+00 27.90 30.90 30.53 28.11 1532+00 28.36 31.36 31.06 28.56 1584+00 27.89 30.89 30.52 28.10 1533+00 28.36 31.36 31.05 28.55 1585+00 27.87 30.87 30.50 28.08 1534+00 28.35 31.35 31.04 28.55 1586+00 27.86 30.86 30.49 28.07 1535+00 28.34 31.34 31.03 28.54 1587+00 27.85 30.85 30.48 28.06 1536+00 28.33 31.33 31.02 28.53 1588+00 27.84 30.84 30.46 28.05 1537+00 28.32 31.32 31.02 28.52 1589+00 27.83 30.83 30.45 28.04 1538+00 28.31 31.31 31.01 28.51 1590+00 27.82 30.82 30.44 28.03 1539+00 28.31 31.31 31.00 28.50 1591+00 27.81 30.81 30.43 28.02 1540+00 28.30 31.30 30.99 28.49 1592+00 27.80 30.80 30.42 28.02 1541+00 28.29 31.29 30.98 28.48 1593+00 27.80 30.80 30.42 28.01 1542+00 28.28 31.28 30.97 28.48 1594+00 27.79 30.79 30.42 28.01 1543+00 28.27 31.27 30.96 28.47 1595+00 27.79 30.79 30.41 28.00 1544+00 28.26 31.26 30.95 28.46 1596+00 27.79 30.79 30.41 28.00 1545+00 28.25 31.25 30.94 28.45 1597+00 27.78 30.78 30.40 28.00 1546+00 28.24 31.24 30.92 28.44 1598+00 27.78 30.78 30.40 27.99 1547+00 28.23 31.23 30.91 28.43 1599+00 27.78 30.78 30.40 27.99 1548+00 28.22 31.22 30.90 28.42 1600+00 27.77 30.77 30.39 27.98 1549+00 28.21 31.21 30.88 28.41 1601+00 27.77 30.77 30.39 27.98 1550+00 28.20 31.20 30.87 28.40 1602+00 27.77 30.77 30.39 27.98 1551+00 28.18 31.18 30.86 28.38 1603+00 27.76 30.76 30.38 27.97 1552+00 28.17 31.17 30.85 28.37 1604+00 27.76 30.76 30.38 27.97 1553+00 28.16 31.16 30.83 28.36 1605+00 27.75 30.75 30.37 27.96 1554+00 28.15 31.15 30.82 28.35 1606+00 27.75 30.75 30.37 27.96 1555+00 28.14 31.14 30.81 28.35 1607+00 27.74 30.74 30.36 27.95 1556+00 28.13 31.13 30.80 28.34 1608+00 27.74 30.74 30.36 27.95 1557+00 28.12 31.12 30.79 28.33 1609+00 27.73 30.73 30.35 27.94 1558+00 28.11 31.11 30.78 28.32 1610+00 27.73 30.73 30.35 27.94 1559+00 28.11 31.11 30.77 28.31 1611+00 27.72 30.72 30.34 27.93 1560+00 28.10 31.10 30.76 28.30 1612+00 27.72 30.72 30.33 27.92 1561+00 28.09 31.09 30.75 28.29 1613+00 27.71 30.71 30.32 27.92 1562+00 28.08 31.08 30.74 28.28 1614+00 27.70 30.70 30.32 27.91 1563+00 28.07 31.07 30.73 28.27 1615+00 27.70 30.70 30.31 27.90 1564+00 28.06 31.06 30.72 28.27 1616+00 27.69 30.69 30.30 27.90 1565+00 28.05 31.05 30.71 28.26 1617+00 27.68 30.68 30.30 27.89 1566+00 28.05 31.05 30.70 28.25 1618+00 27.67 30.67 30.29 27.88 1567+00 28.04 31.04 30.69 28.24 1619+00 27.67 30.67 30.28 27.88 1568+00 28.03 31.03 30.68 28.24 1620+00 27.66 30.66 30.28 27.87 1569+00 28.02 31.02 30.68 28.23 1621+00 27.66 30.66 30.28 27.87 1570+00 28.02 31.02 30.67 28.22 1622+00 27.66 30.66 30.27 27.87 1571+00 28.01 31.01 30.66 28.22 1623+00 27.66 30.66 30.27 27.87 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-13 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1624+00 27.66 30.66 30.27 27.86 1676+00 27.31 30.75 29.89 27.88 1625+00 27.66 30.66 30.27 27.86 1677+00 27.29 30.73 29.87 27.86 1626+00 27.65 30.65 30.27 27.86 1678+00 27.28 30.71 29.85 27.84 1627+00 27.65 30.65 30.27 27.86 1679+00 27.26 30.69 29.83 27.82 1628+00 27.65 30.65 30.27 27.86 1680+00 27.24 30.67 29.81 27.80 1629+00 27.65 30.65 30.27 27.85 1681+00 27.22 30.65 29.79 27.78 1630+00 27.65 30.65 30.26 27.85 1682+00 27.21 30.63 29.76 27.75 1631+00 27.64 30.64 30.26 27.84 1683+00 27.19 30.60 29.74 27.73 1632+00 27.64 30.64 30.25 27.84 1684+00 27.17 30.59 29.73 27.72 1633+00 27.63 30.65 30.25 27.84 1685+00 27.17 30.57 29.72 27.70 1634+00 27.63 30.67 30.25 27.83 1686+00 27.16 30.56 29.71 27.69 1635+00 27.63 30.68 30.24 27.83 1687+00 27.15 30.55 29.70 27.67 1636+00 27.62 30.70 30.24 27.82 1688+00 27.14 30.54 29.69 27.66 1637+00 27.62 30.71 30.24 27.82 1689+00 27.13 30.53 29.68 27.64 1638+00 27.61 30.72 30.23 27.81 1690+00 27.13 30.52 29.67 27.63 1639+00 27.61 30.74 30.23 27.81 1691+00 27.12 30.51 29.66 27.61 1640+00 27.60 30.75 30.22 27.80 1692+00 27.11 30.49 29.65 27.60 1641+00 27.60 30.76 30.21 27.80 1693+00 27.10 30.48 29.64 27.58 1642+00 27.59 30.77 30.21 27.79 1694+00 27.09 30.47 29.63 27.57 1643+00 27.58 30.78 30.20 27.78 1695+00 27.09 30.46 29.62 27.55 1644+00 27.58 30.79 30.19 27.78 1696+00 27.08 30.45 29.62 27.54 1645+00 27.57 30.80 30.18 27.77 1697+00 27.08 30.44 29.62 27.53 1646+00 27.56 30.81 30.18 27.76 1698+00 27.07 30.44 29.61 27.51 1647+00 27.56 30.83 30.17 27.75 1699+00 27.07 30.43 29.61 27.50 1648+00 27.55 30.84 30.16 27.75 1700+00 27.06 30.42 29.60 27.49 1649+00 27.54 30.85 30.15 27.74 1701+00 27.06 30.41 29.60 27.48 1650+00 27.54 30.86 30.15 27.73 1702+00 27.06 30.40 29.59 27.46 1651+00 27.53 30.87 30.14 27.73 1703+00 27.05 30.39 29.59 27.45 1652+00 27.52 30.88 30.13 27.72 1704+00 27.05 30.39 29.58 27.44 1653+00 27.52 30.89 30.12 27.72 1705+00 27.05 30.38 29.58 27.43 1654+00 27.51 30.90 30.12 27.71 1706+00 27.04 30.38 29.58 27.42 1655+00 27.50 30.91 30.11 27.77 1707+00 27.04 30.37 29.58 27.41 1656+00 27.50 30.93 30.10 27.84 1708+00 27.04 30.37 29.58 27.40 1657+00 27.49 30.94 30.10 27.90 1709+00 27.04 30.37 29.58 27.40 1658+00 27.48 30.95 30.09 27.97 1710+00 27.04 30.36 29.58 27.39 1659+00 27.48 30.96 30.08 28.03 1711+00 27.04 30.36 29.58 27.38 1660+00 27.47 30.97 30.07 28.10 1712+00 27.04 30.35 29.58 27.37 1661+00 27.46 30.96 30.07 28.16 1713+00 27.04 30.35 29.58 27.36 1662+00 27.46 30.95 30.06 28.15 1714+00 27.04 30.34 29.58 27.36 1663+00 27.45 30.94 30.05 28.13 1715+00 27.03 30.33 29.57 27.35 1664+00 27.44 30.93 30.04 28.11 1716+00 27.03 30.33 29.57 27.35 1665+00 27.43 30.92 30.03 28.09 1717+00 27.03 30.32 29.57 27.35 1666+00 27.43 30.90 30.03 28.07 1718+00 27.02 30.31 29.56 27.34 1667+00 27.42 30.89 30.02 28.05 1719+00 27.02 30.31 29.56 27.34 1668+00 27.41 30.88 30.01 28.03 1720+00 27.01 30.30 29.55 27.33 1669+00 27.40 30.87 30.00 28.02 1721+00 27.01 30.29 29.54 27.33 1670+00 27.40 30.86 29.99 28.00 1722+00 27.00 30.28 29.54 27.32 1671+00 27.39 30.85 29.99 27.98 1723+00 26.99 30.27 29.53 27.31 1672+00 27.38 30.84 29.98 27.96 1724+00 26.99 30.26 29.52 27.31 1673+00 27.37 30.82 29.96 27.94 1725+00 26.98 30.25 29.52 27.30 1674+00 27.35 30.80 29.94 27.92 1726+00 26.98 30.24 29.51 27.29 1675+00 27.33 30.78 29.92 27.90 1727+00 26.97 30.23 29.50 27.29 SAFCA April 9 2025
American River South Levee System - Determination of the UDLC DWSE, MTOL, and HTOL Page D-14 Table D-2. ULDC Hydraulic Parameter Profiles, Sacramento River East Levee (cont.) Levee
Station
(feet)
DWSE
(feet)
MTOL
(feet)
HTOL
(feet)
SVRP
(feet)
1728+00 26.96 30.22 29.50 27.28
1729+00 26.96 30.21 29.49 27.28
1730+00 26.97 30.21 29.50 27.29
1731+00 26.95 30.19 29.48 27.27
1732+00 26.94 30.18 29.47 27.26
1733+00 26.93 30.17 29.46 27.25
1734+00 26.92 30.15 29.45 27.25
1735+00 26.91 30.14 29.44 27.24
1736+00 26.91 30.13 29.43 27.23
1737+00 26.90 30.12 29.42 27.22
1738+00 26.89 30.11 29.41 27.21
1739+00 26.88 30.09 29.40 27.20
1740+00 26.87 30.08 29.39 27.19
1741+00 26.86 30.07 29.38 27.18
1742+00 26.85 30.05 29.37 27.17
1743+00 26.84 30.04 29.36 27.16
1744+00 26.83 30.02 29.34 27.15
1745+00 26.82 30.01 29.33 27.14
1746+00 26.81 30.00 29.32 27.13
1747+00 26.80 29.98 29.31 27.12
1748+00 26.79 29.97 29.30 27.11
1749+00 26.78 29.95 29.29 27.10
1750+00 26.77 29.94 29.27 27.09
1751+00 26.76 29.93 29.26 27.08
1752+00 26.75 29.91 29.25 27.07
1753+00 26.74 29.90 29.24 27.07
1754+00 26.74 29.89 29.24 27.06
1755+00 26.73 29.89 29.23 27.06
1756+00 26.73 29.88 29.23 27.06
1757+00 26.72 29.87 29.22 27.05
1758+00 26.72 29.86 29.22 27.05
1759+00 26.71 29.85 29.21 27.04
1760+00 26.71 29.85 29.21 27.04
1761+00 26.71 29.84 29.20 27.03
1762+00 26.70 29.83 29.20 27.03
1763+00 26.70 29.82 29.20 27.03
1764+00 26.69 29.81 29.19 27.02
1765+00 26.69 29.81 29.19 27.02
1766+00 26.68 29.80 29.18 27.01
1767+00 26.68 29.79 29.17 27.00
1768+00 26.67 29.78 29.16 27.00
1769+00 26.66 29.77 29.16 26.99
1770+00 26.65 29.75 29.15 26.98

APPENDIX B
___________________________________________________________________________________

LIST OF ATTACHMENTS
Kleinfelder 2025 American River South Levee System Swimming Pools Evaluation Table B-1 Swimming Pool Geotechnical Review Summary - 2025 200-Year DWSE Table B-2 Swimming Pool Geotechnical Review Summary - 2025 HTOL 24001006.001A/SAC24R176178 Page 1 of 6 April 17, 2025
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Table B-1
Swimming Pool Geotechnical Review Summary - 2025 200-Year DWSE ULDC
Analysis
Reach / Pool
No.

SCB DMM
cutoff wall
20 13 Yes Yes No 30.7 22 27.1 0.32 0.63 0.59
SREL-C / 2 1258+27 31 1260+50 21 14 Yes Yes No 30.6 22.5 26.0 0.21 0.52 0.56 SREL-C / 3 1259+09 39 1260+50 21 14 Yes Yes No 30.6 22.5 26.0 0.21 0.52 0.58 SREL-C / 4 1261+90 36 1265+00
2003 SAFCA

SCB DMM
cutoff wall
20 13 Yes Yes No 30.6 11 22.7 0.23 0.84 0.57
SREL-C / 5 1263+20 47 1265+00 20 13 Yes Yes No 30.5 11 22.6 0.23 0.83 0.59 SREL-C / 6 1264+10 40 1265+00 22 15 Yes Yes No 30.5 11 22.6 0.05 0.66 0.58 SREL-C / 7 1265+10 35 1265+00 21 14 Yes Yes No 30.5 11 22.6 0.14 0.75 0.57 SREL-C / 8 1266+25 20 1265+00 21 14 Yes Yes No 30.5 11 22.6 0.14 0.75 0.54 SREL-C / 9 1267+00 54 1265+00 20 13 Yes Yes No 30.5 11 22.6 0.23 0.83 0.61 SREL-C / 10 1268+00 60 1265+00 20 13 Yes Yes No 30.5 11 22.6 0.23 0.83 0.62 SREL-C / 11 1279+40 70 1265+00 21 14 Yes Yes Yes 30.4 11 22.5 0.13 0.74 0.64 SREL-C / 12 1280+75 35 1265+00 20 13 Yes Yes No 30.4 11 22.5 0.22 0.83 0.57 SREL-C / 13 1283+80 75 1265+00 20 13 Yes Yes Yes 30.4 11 22.5 0.22 0.83 0.65 SREL-C / 14 1284+40 15 1265+00 21 14 Yes No No 30.4 11 22.5 0.13 0.74 0.53 24001006.001A/SAC24R176178 Page 2 of 6 April 17, 2025
© 2024 Kleinfelder www.kleinfelder.com
ULDC
Analysis
Reach / Pool
No.

SCB DMM
cutoff wall
21 14 Yes No No 29.2 12 12.6 <0.01 <0.01 0.52
SREL-D / 2 1425+25 27 1425+00 20 13 Yes Yes No 29.1 12 12.5 <0.01 <0.01 0.55 SREL-D / 3 1426+34 48 1425+00 21 14 Yes Yes No 29.1 10 12.5 <0.01 <0.01 0.60 SREL-D / 4 1429+27 15 1425+00 21 14 Yes No No 29.1 12 12.5 <0.01 <0.01 0.53 SREL-D / 5 1431+00 41 1425+00 21 14 Yes Yes No 29.1 10 12.5 <0.01 <0.01 0.58 SREL-D / 6 1432+00 18 1425+00 21 14 Yes No No 29.1 12 12.5 <0.01 <0.01 0.54 SREL-D / 7 1435+00 40 1425+00 21 14 Yes Yes No 29.1 10 12.5 <0.01 <0.01 0.58 SREL-D / 8 1437+46 0 1425+00 20 13 No No No 29.0 12 12.4 <0.01 <0.01 0.50 SREL-D / 9 1443+13 16 1439+02
2022 USACE
SB opentrench cutoff
wall
20 13 Yes No No 29.0 21.5 10.5 <0.01 <0.01 0.53
SREL-D / 10 1446+20 41 1449+00 19 12 Yes Yes No 29.0 13 8.8 <0.01 <0.01 0.58 SREL-D / 11 1447+15 64 1449+00 19 12 Yes Yes No 29.0 13 8.8 <0.01 <0.01 0.63 SREL-D / 12 1450+50 10 1449+00 21 14 Yes No No 29.0 13 8.8 <0.01 <0.01 0.52 SREL-D / 13 1451+50 20 1449+00 19 12 Yes Yes No 29.0 13 8.8 <0.01 <0.01 0.54 SREL-D / 14 1463+10 55 1449+00 19 12 Yes Yes No 28.8 13 8.6 <0.01 <0.01 0.61 SREL-D / 15 1463+60 85 1471+30 19 12 Yes Yes Yes 28.8 11 8.1 <0.01 <0.01 0.67 SREL-D / 16 1469+50 20 1471+30 21 14 Yes Yes No 28.8 11 8.1 <0.01 <0.01 0.54 SREL-D / 17 1469+80 45 1471+30 20 13 Yes Yes No 28.8 11 8.1 <0.01 <0.01 0.59 SREL-D / 18 1472+50 60 1471+30 20 13 Yes Yes No 28.8 11 8.1 <0.01 <0.01 0.62 SREL-D / 19 1476+80 30 1471+30 23 16 Yes Yes No 28.7 11 8.0 <0.01 <0.01 0.56 24001006.001A/SAC24R176178 Page 3 of 6 April 17, 2025
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ULDC
Analysis
Reach / Pool
No.

SCB DMM
cutoff wall
18 11 Yes Yes Yes 28.4 2 9.3 <0.01 <0.01 0.64
SREL-E / 1 1641+50 90 1648+00
1993 USACE
Phase II SCB
mix-in-place
cutoff wall
17 10 Yes Yes Yes 27.6 24 24.9 0.32 0.61 0.68
SREL-E / 2 1649+10 90 1650+00 16 9 Yes Yes Yes 27.5 17.5 25.0 0.50 0.89 0.68 SREL-E / 3 1651+50 65 1653+00 18 11 Yes Yes No 27.5 40 22.4 0.11 0.28 0.63 SREL-E / 4 1654+50 65 1653+00 18 11 Yes Yes No 27.5 40 22.4 0.11 0.28 0.63 SREL-E / 5 1656+70 95 1653+00 18 11 Yes Yes Yes 27.5 40 21.4 0.08 0.26 0.69 1- Refer to seepage analysis sources in Table 2.7.
2- Each pool was assumed to be 7 feet deep.
24001006.001A/SAC24R176178 Page 4 of 6 April 17, 2025
© 2024 Kleinfelder www.kleinfelder.com
Table B-2
Swimming Pool Geotechnical Review Summary - 2025 HTOL
ULDC
Analysis
Reach / Pool
No.

Station at
Pool
Location
Distance
from
Landside
Levee Toe
(ft)
Representative
Seepage Analysis
Cross Section1
Existing
Remediation
Ground Surface
Elevation
Adjacent to
Pool, Google
Earth (ft,
NAVD88)
Bottom of
Pool
Elevation2
(ft, NAVD88)
Meets Title
23 Minimum
10‐ft
Setback?
USACE (2022) Geotechnical
Levee Practice Setback
Requirements
2025
HTOL (ft)
Blanket
Layer
Thickness
Beneath
Pool (ft)
Total Head
at Bottom of
Blanket at
Pool
Location
Revised Average Exit Gradient at bottom of Pool
Meets
Minimum
20‐ft
Setback?
Meets
Minimum 10
x Pool Depth
Setback?
Gradient at
Pool Location
[Full Pool]
Gradient at
Pool Location
(Empty Pool)
Allowable
Gradient
SREL-A / 1 1003+00 30 1005+00
2000 USACE SCB
cutoff wall
29 22 Yes Yes No 36.4 26 33.6 0.18 0.44 0.56
SREL-A / 2 1008+50 80 1005+00 31 24 Yes Yes Yes 36.3 26 33.0 0.08 0.34 0.66 SREL-C / 1 1250+59 44 1249+50
2024 USACE SCB
DMM cutoff wall
20 13 Yes Yes No 33.6 22 29.5 0.42 0.73 0.59
SREL-C / 2 1258+27 31 1260+50 21 14 Yes Yes No 33.5 22.5 27.5 0.28 0.59 0.56 SREL-C / 3 1259+09 39 1260+50 21 14 Yes Yes No 33.5 22.5 27.5 0.28 0.59 0.58 SREL-C / 4 1261+90 36 1265+00
2003 SAFCA SCB
DMM cutoff wall
20 13 Yes Yes No 33.5 11 23.8 0.33 0.94 0.57
SREL-C / 5 1263+20 47 1265+00 20 13 Yes Yes No 33.4 11 23.7 0.32 0.93 0.59 SREL-C / 6 1264+10 40 1265+00 22 15 Yes Yes No 33.4 11 23.7 0.15 0.76 0.58 SREL-C / 7 1265+10 35 1265+00 21 14 Yes Yes No 33.4 11 23.9 0.25 0.86 0.57 SREL-C / 8 1266+25 20 1265+00 21 14 Yes Yes No 33.4 11 23.9 0.25 0.86 0.54 SREL-C / 9 1267+00 54 1265+00 20 13 Yes Yes No 33.4 11 23.7 0.32 0.93 0.61 SREL-C / 10 1268+00 60 1265+00 20 13 Yes Yes No 33.4 11 23.7 0.32 0.93 0.62 SREL-C / 11 1279+40 70 1265+00 21 14 Yes Yes Yes 33.3 11 23.4 0.21 0.82 0.64 SREL-C / 12 1280+75 35 1265+00 20 13 Yes Yes No 33.3 11 23.6 0.31 0.92 0.57 SREL-C / 13 1283+80 75 1265+00
2020 USACE SCB
DMM cutoff wall
20 13 Yes Yes Yes 33.3 11 23.4 0.30 0.90 0.65
SREL-C / 14 1284+40 15 1265+00 21 14 Yes No No 33.3 11 23.6 0.23 0.83 0.53 24001006.001A/SAC24R176178 Page 5 of 6 April 17, 2025
© 2024 Kleinfelder www.kleinfelder.com
ULDC
Analysis
Reach / Pool
No.

Station at
Pool
Location
Distance
from
Landside
Levee Toe
(ft)
Representative
Seepage Analysis
Cross Section1
Existing
Remediation
Ground Surface
Elevation
Adjacent to
Pool, Google
Earth (ft,
NAVD88)
Bottom of
Pool
Elevation2
(ft, NAVD88)
Meets Title
23 Minimum
10‐ft
Setback?
USACE (2022) Geotechnical
Levee Practice Setback
Requirements
2025
HTOL (ft)
Blanket
Layer
Thickness
Beneath
Pool (ft)
Total Head
at Bottom of
Blanket at
Pool
Location
Revised Average Exit Gradient at bottom of Pool
Meets
Minimum
20‐ft
Setback?
Meets
Minimum 10
x Pool Depth
Setback?
Gradient at
Pool Location
[Full Pool]
Gradient at
Pool Location
(Empty Pool)
Allowable
Gradient
SREL-D / 1 1422+60 10 1425+00
2022 USACE SCB
DMM cutoff wall
21 14 Yes No No 31.9 12 13.4 <0.01 <0.01 0.52
SREL-D / 2 1425+25 27 1425+00 20 13 Yes Yes No 31.9 12 13.4 <0.01 0.03 0.55 SREL-D / 3 1426+34 48 1425+00 21 14 Yes Yes No 31.9 10 13.4 <0.01 <0.01 0.60 SREL-D / 4 1429+27 15 1425+00 21 14 Yes No No 31.8 12 13.3 <0.01 <0.01 0.53 SREL-D / 5 1431+00 41 1425+00 21 14 Yes Yes No 31.8 10 13.3 <0.01 <0.01 0.58 SREL-D / 6 1432+00 18 1425+00 21 14 Yes No No 31.8 12 13.3 <0.01 <0.01 0.54 SREL-D / 7 1435+00 40 1425+00 21 14 Yes Yes No 31.8 10 13.3 <0.01 <0.01 0.58 SREL-D / 8 1437+46 0 1425+00 20 13 No No No 31.8 12 13.3 <0.01 0.02 0.50 SREL-D / 9 1443+13 16 1439+02
2022 USACE SB
open-trench
cutoff wall
20 13 Yes No No 31.8 21.5 11.5 <0.01 <0.01 0.53
SREL-D / 10 1446+20 41 1449+00 19 12 Yes Yes No 31.8 13 9.7 <0.01 <0.01 0.58 SREL-D / 11 1447+15 64 1449+00 19 12 Yes Yes No 31.8 13 9.7 <0.01 <0.01 0.63 SREL-D / 12 1450+50 10 1449+00 21 14 Yes No No 31.7 13 9.7 <0.01 <0.01 0.52 SREL-D / 13 1451+50 20 1449+00 19 12 Yes Yes No 31.7 13 9.7 <0.01 <0.01 0.54 SREL-D / 14 1463+10 55 1449+00 19 12 Yes Yes No 31.6 13 9.6 <0.01 <0.01 0.61 SREL-D / 15 1463+60 85 1471+30 19 12 Yes Yes Yes 31.6 11 9.0 <0.01 <0.01 0.67 SREL-D / 16 1469+50 20 1471+30 21 14 Yes Yes No 31.5 11 9.1 <0.01 <0.01 0.54 SREL-D / 17 1469+80 45 1471+30 20 13 Yes Yes No 31.5 11 9.0 <0.01 <0.01 0.59 SREL-D / 18 1472+50 60 1471+30 20 13 Yes Yes No 31.5 11 9.0 <0.01 <0.01 0.62 SREL-D / 19 1476+80 30 1471+30 23 16 Yes Yes No 31.4 11 9.0 <0.01 <0.01 0.56 SREL-D / 20 1489+14 49 1497+40
2022 USACE
SCCB opentrench cutoff
wall
20 13 Yes Yes No 31.3 25 25.5 0.22 0.49 0.60
SREL-D / 21 1490+05 61 1497+40 20 13 Yes Yes No 31.3 25 25.0 0.20 0.47 0.62 SREL-D / 22 1491+60 30 1497+40 21 14 Yes Yes No 31.3 25.5 25.5 0.17 0.44 0.56 24001006.001A/SAC24R176178 Page 6 of 6 April 17, 2025
© 2024 Kleinfelder www.kleinfelder.com
ULDC
Analysis
Reach / Pool
No.

Station at
Pool
Location
Distance
from
Landside
Levee Toe
(ft)
Representative
Seepage Analysis
Cross Section1
Existing
Remediation
Ground Surface
Elevation
Adjacent to
Pool, Google
Earth (ft,
NAVD88)
Bottom of
Pool
Elevation2
(ft, NAVD88)
Meets Title
23 Minimum
10‐ft
Setback?
USACE (2022) Geotechnical
Levee Practice Setback
Requirements
2025
HTOL (ft)
Blanket
Layer
Thickness
Beneath
Pool (ft)
Total Head
at Bottom of
Blanket at
Pool
Location
Revised Average Exit Gradient at bottom of Pool
Meets
Minimum
20‐ft
Setback?
Meets
Minimum 10
x Pool Depth
Setback?
Gradient at
Pool Location
[Full Pool]
Gradient at
Pool Location
(Empty Pool)
Allowable
Gradient
SREL-D / 23 1499+25 70 1511+00
2022 USACE SB
open-trench
cutoff wall
17 10 Yes Yes Yes 31.3 20 24.5 0.37 0.71 0.64
SREL-D / 24 1499+60 91 1511+00 17 10 Yes Yes Yes 31.3 20 24.5 0.37 0.71 0.68 SREL-D / 25 1501+46 71 1511+00 17 10 Yes Yes Yes 31.3 20 24.5 0.37 0.71 0.64 SREL-D / 26 1506+38 57 1511+00 19 12 Yes Yes No 31.3 20.5 24.5 0.26 0.60 0.61 SREL-D / 27 1507+38 23 1511+00 17 10 Yes Yes No 31.2 21.5 25.8 0.40 0.72 0.55 SREL-D / 28 1512+20 48 1511+00 17 10 Yes Yes No 31.2 20.5 24.4 0.35 0.69 0.60 SREL-D / 29 1512+58 87 1511+00 16 9 Yes Yes Yes 31.2 20 24.4 0.41 0.75 0.67 SREL-D / 30 1515+02 48 1511+00 17 10 Yes Yes No 31.2 20.5 24.4 0.35 0.69 0.60 SREL-D / 31 1518+25 52 1511+00 17 10 Yes Yes No 31.2 20.5 24.4 0.35 0.69 0.60 SREL-D / 32 1525+25 70 1524+04 2022 USACE SCB
DMM cutoff wall 18 11 Yes Yes Yes 31.1 2 10.1 <0.01 <0.01 0.64 SREL-E / 1 1641+50 90 1648+00
1993 USACE
Phase II SCB
mix-in-place
cutoff wall
17 10 Yes Yes Yes 30.2 24 27.1 0.41 0.70 0.68
SREL-E / 2 1649+10 90 1650+00 16 9 Yes Yes Yes 30.2 17.5 27.3 0.63 1.02 0.68 SREL-E / 3 1651+50 65 1653+00 18 11 Yes Yes No 30.1 40 23.9 0.15 0.32 0.63 SREL-E / 4 1654+50 65 1653+00 18 11 Yes Yes No 30.1 40 23.9 0.15 0.32 0.63 SREL-E / 5 1656+70 95 1653+00 18 11 Yes Yes Yes 30.1 40 22.9 0.12 0.29 0.69 1- Refer to seepage analysis sources in Table 2.7.
2- Each pool was assumed to be 7 feet deep.

APPENDIX C
___________________________________________________________________________________

LIST OF ATTACHMENTS
Kleinfelder, 2025. “Seismic Performance Summary Report, American River South Levee System, ULDC & FEMA Levee Certification Project, Sacramento Area Flood Control Agency Levee Systems, Sacramento County, California.” Dated April 16, 2025.
24001006.001A/SAC25R179413 Page i of vi April 16, 2025
© 2025 Kleinfelder

SEISMIC PERFORMANCE SUMMARY REPORT

AMERICAN RIVER SOUTH LEVEE SYSTEM

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SACRAMENTO AREA FLOOD CONTROL AGENCY LEVEE SYSTEMS

SACRAMENTO COUNTY, CALIFORNIA
APRIL 16, 2025
Copyright 2025 Kleinfelder
All Rights Reserved
24001006.001A/SAC25R179413 Page ii of vi April 16, 2025 © 2025 Kleinfelder
April 16, 2025
File No.: 24001006.001A
Mr. Dan Tibbitts, PE
Principal Engineering
Sacramento Area Flood Control Agency
1325 J Street, Suite 1700
Sacramento, CA 95814
Subject: DRAFT Seismic Performance Summary Report
American River South Levee System
ULDC & FEMA Levee Certification Project
Sacramento Area Flood Control Agency Levee Systems
Sacramento County, California
Kleinfelder Project # 24001006.001A
Dear Mr. Tibbitts:

Kleinfelder has been tasked by the Sacramento Area Flood Control Agency (SAFCA) with evaluating the seismic vulnerability of the Sacramento area levees located in Sacramento and Sutter Counties, California in support of the Urban Levee Design Criteria (ULDC) (DWR, 2012) level certification. For the evaluation, the Sacramento area levees have been divided into three areas - Natomas Basin, American River South Levee System (ARSLS), and North Area Streams (NAS). A separate Seismic Performance Summary Report (SPSR) will be prepared for each of the three areas.

The purpose of this SPSR is to document Kleinfelder’s findings, present evaluation results, and present anticipated seismic segment performance for the ARSLS. This document provides the analysis to support the development of a forthcoming Post-Earthquake Response Plan (PERP).

The American River South Levee System area includes the American River South Levee (ARSL), Sacramento River East Levee (SREL), and Beach Lake North Levee (BLNL) located within Sacramento County, California, as shown on Figure 1-1.
24001006.001A/SAC25R179413 Page iii of vi April 16, 2025 © 2025 Kleinfelder
This report has been prepared consistent with the requirements of the approved scope of work for the subject project outlined in Kleinfelder’s proposal dated May 5, 2023.

Sincerely,
KLEINFELDER, INC.

Ryan Hochstatter, EIT Zia Zafir PE, GE
Professional Sr. Principal Geotechnical Engineer
Reviewed By:

Timothy A. Williams, PE, GE
Sr. Principal Geotechnical Engineer
CC: Mr. Pro Mitra, PE/MBK Engineers ([email protected]) Ms. Becky Money, PE/MBK Engineers ([email protected]) 24001006.001A/SAC25R179413 Page iv of vi April 16, 2025 © 2025 Kleinfelder

TABLE OF CONTENTS

SECTION PAGE
1 INTRODUCTION .........................................................................................................................1

1.1 PURPOSE AND SCOPE ......................................................................................................... 1

1.2 BACKGROUND..................................................................................................................... 1

1.3 PROJECT STATIONING AND DATUMS ................................................................................. 2

1.4 REFERENCED REPORTS........................................................................................................ 2

1.5 SEISMIC VULNERABILITY EVALUATION METHODOLOGY.................................................... 3

1.5.1 PRELIMINARY WORK.............................................................................................. 3

1.5.2 PHASE 1: SCREENING REVIEW OF EXISTING ANALYSIS.......................................... 3

1.5.3 PHASE 2: TARGETED EVALUATION ........................................................................ 4

1.5.4 SEISMIC VULNERABILITY ........................................................................................ 5

1.5.5 SEISMIC DEFORMATION MODELING ..................................................................... 7 2 GEOLOGY AND GEOMORPHOLOGY.............................................................................................8

2.1 REGIONAL GEOLOGIC SETTING........................................................................................... 8

2.2 LOCAL GEOLOGY ................................................................................................................. 9

2.2.1 SURFICIAL GEOLOGY .............................................................................................. 9

2.2.2 GENERALIZED NEAR SURFACE STRATIGRAPHY.................................................... 12

2.3 SEISMOTECTONIC SETTING............................................................................................... 13 3 GROUND MOTION HAZARD ANALYSIS ......................................................................................14

3.1 SEISMIC HAZARD ANALYSIS .............................................................................................. 14

3.1.1 SEISMIC ANALYSIS RESULTS................................................................................. 15 4 PREVIOUS EVALUATION...........................................................................................................16

4.1 SUMMARY......................................................................................................................... 16

4.1.1 GENERAL .............................................................................................................. 16

4.2 SEISMIC ANALYSIS WATER SURFACE ELEVATIONS ........................................................... 17 5 CURRENT EVALUATION ............................................................................................................19

5.1 SEISMIC EVALUATION SEGMENT SELECTION ................................................................... 19

5.1.1 LIQUEFACTION ANALYSIS OF ULDC SEGMENTS................................................... 19

5.2 VULNERABILITY CLASSIFICATIONS FOR TARGETED SEGMENTS........................................ 22

5.2.1 SEGMENT ARSL-4................................................................................................. 22

5.2.2 SEGMENT ARSL-6................................................................................................. 23

5.2.3 SEGMENT SREL-9 ................................................................................................. 23

5.2.4 SEGMENT BLNL-4................................................................................................. 24

5.2.5 SEGMENT BLNL-2................................................................................................. 25

5.3 SEISMIC DEFORMATION MODELING RESULTS ................................................................. 25 6 SEISMIC PERFORMANCE...........................................................................................................27

6.1 SUMMARY......................................................................................................................... 27 7 LIMITATIONS ...........................................................................................................................28 8 REFERENCES ............................................................................................................................29 24001006.001A/SAC25R179413 Page v of vi April 16, 2025
© 2025 Kleinfelder
TABLES

3.1 Seismic Hazard Analysis Site Parameters

3.2 Probabilistic Peak Horizontal Acceleration and Controlling Earthquake Magnitude

4.1 Phase 1 - Seismic Vulnerability Results Screening

5.1.1 ARSLS – 2015 Post-Seismic Model Liquefiable Layers

5.1.2 ARSLS – Liquefaction Layer Changes for Targeted Segments

5.1.3 ARSLS – Liquefiable Layer Classification and Factor of Safety Changes for Targeted Segments

5.2.1 ARSLS – 2015 BLNL-4 Post-Seismic Stability Analysis Factors of Safety

6.1 Seismic Vulnerability Classifications for American River South Levee System

FIGURES
1-1 Site Map
1-2 Table 6-1 from DWR Guidance Document, Section 6.4 (pg. 7) 1-3 Seismic Evaluation Workflow Chart
2-1 Regional Geology
2-2 American River South Levee Geology Map
2-3 Sacramento River East Levee Geology Map
2-4 Beach Lake North Levee Geology Map
6-1 Seismic Vulnerability Classifications for American River South Levee System Segments

APPENDIX
A Seismic Technical Approach Memo
B Ground Motion Parameter Selection Memo
C Section 6, Seismic Analysis, Guidance Document for Geotechnical Analyses, Urban Levee Evaluations Project
D Updated SPT-Based Liquefaction Calculations for Targeted Segments E Original SPT-Based Liquefaction Calculations for Targeted Segments F Seismic Deformation Modeling Appendix
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REPORT ACRONYMS
___________________________________________________________________________________ 200-year 200-year median (i.e., flood recurrence period) ARCF American River Common Features
ARSL American River South Levee
ARSLS American River South Levee System
BLNL Beach Lake North Levee
DRMS Delta Risk Management Strategy
DWR California Department of Water Resources
FEMA Federal Emergency Management Agency
FOS Factor of Safety
FWLA Fugro William Lettis & Associates, Inc.

GER Geotechnical Evaluation Report
GMHA Ground Motion Hazard Analysis
GMM Ground Motion Model
GMPSM Ground Motion Parameter Selection Memorandum
KLF Kleinfelder
km Kilometer
Kmax Maximum Horizontal Seismic Coefficient
Ky Yield Acceleration
Mw Earthquake Magnitude
NAS North Area Streams Levees
NCC Natomas Creek Canal
NE Northeast
NGA Next Generation Attenuation
NW Northwest
PERP Post-Earthquake Response Plan
PHA Peak Horizontal Acceleration
PSHA Probabilistic Seismic Hazard Analysis
SAFCA Sacramento Area Flood Control Agency
SETAM Seismic Evaluation Technical Analysis Memorandum
SNGV Sierra Nevada-Great Valley block
SPSR Seismic Performance Summary Report
SPT Standard Penetration Test
SREL Sacramento River East Levee
ULDC Urban Levee Design Criteria
ULE Urban Levee Evaluation
URS URS Corporation
USACE United States Army Corps of Engineers
WUS Western United States
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© 2025 Kleinfelder
1 INTRODUCTION
____________________________________________________________________________

1.1 PURPOSE AND SCOPE
Kleinfelder has been tasked by the Sacramento Area Flood Control Agency (SAFCA) with evaluating the seismic vulnerability of the Sacramento area levees within the SAFCA flood control system located in Sacramento and Sutter Counties, California in support of the Urban Levee Design Criteria (ULDC) (DWR, 2012) level certification. For the evaluation, the Sacramento area levees have been divided into three areas - Natomas Basin, American River South Levee System (ARSLS), and North Area Streams (NAS). A separate Seismic Performance Summary Report (SPSR) will be prepared for each of the three areas.

The purpose of this SPSR is to document Kleinfelder’s findings, present evaluation results, and present anticipated seismic segment performance for the ARSLS levees. This document provides the analysis to support the development of a forthcoming Post-Earthquake Response Plan (PERP).

The ARSLS area includes the American River South Levee (ARSL), Sacramento River East Levee (SREL), and Beach Lake North Levee (BLNL) located within Sacramento County, California, as shown on Figure 1-

1. This report has been prepared consistent with the requirements of the approved scope of work for the subject project outlined in Kleinfelder’s proposal dated May 5, 2023, and Amendment No. 1 Contract No. 1591 dated February 5, 2025.

1.2 BACKGROUND
The study area levees in the greater Sacramento area were constructed over a period of years, with original construction of many reaches started around the turn of the last century. Since that time, many changes have been made to the system to meet modern flood control standards, accommodate changes in land use, and make the system more resilient to impacts from climate change and other factors.

As part of recent modernization efforts, The American River Common Features (ARCF) Project improvements were authorized by the Federal Government for construction by Section 1401(2)(7) of the Water Infrastructure Improvements for the Nation Act of 2016 (Pub. L. No. 114-322, § 1401(2)(7), 130 Stat. 1708, 1710 (2016)). The ARCF authorized work is nearing completion under the oversight of the 24001006.001A/SAC25R179413 Page 2 of 32 April 16, 2025
© 2025 Kleinfelder
U.S. Army Corps of Engineers (USACE) in cooperation with SAFCA and the California Department of Water Resources. Other locally sponsored modernization efforts and repair work are also or will soon be completed. As such, it is expected that by or about 2026, SAFCA will be working to apply for FEMA certification and will as part of that effort show compliance with ULDC requirements.

To better understand the potential flood risk to urban areas of California posed by levees, the California Department of Water Resources (DWR) conducted the Urban Levee Evaluations (ULE) project. As part of this effort, URS Corporation (URS) classified the seismic vulnerability of the ARSLS levees in the Geotechnical Evaluation Reports (GER) for the American River Study Area (URS, 2015a), Sacramento River Study Area (URS, 2015b), and the South Sacramento Streams Study Area (URS, 2015c). The analyses performed for these reports were reviewed and used for this report.

1.3 PROJECT STATIONING AND DATUMS
Elevation references in this report are in feet and are based on the North American Vertical Datum of 1988 (NAVD88). Project stationing used in this report is based on the DWR system developed for the Urban Levee Evaluation (ULE) project (URS, 2014). The ULE stationing is shown on Figure 1-1.

1.4 REFERENCED REPORTS
The following GERs were reviewed in support of this ARSLS SPSR:
• “ULE Geotechnical Evaluation Report, American River Study Area, Urban Levee Evaluations Project, Contract 4600008101,” dated January 2015 (Issue date: 02-16-2015), URS (2015a). • “ULE Geotechnical Evaluation Report Volume 2, Remedial Alternatives, Sacramento River Study Area, Urban Levee Evaluations Project, Contract 4600008101,” dated January 2015 (Issue date:
02-04-2015), URS (2015b).
• “ULE Geotechnical Evaluation Report Volume 2, Remedial Alternatives, South Sacramento Streams Study Area, Urban Levee Evaluations Project, Contract 4600008101,” dated April 2015 (Issue date: 04-21-2015), URS (2015c).
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1.5 SEISMIC VULNERABILITY EVALUATION METHODOLOGY
The seismic vulnerability evaluation was performed in accordance with Kleinfelder’s Seismic Evaluation Technical Approach Memorandum (SETAM) (Kleinfelder, 2023a) contained in Appendix A, which is generally consistent with the Urban Levee Evaluations Project Guidance Document for Geotechnical Analysis (URS, 2015d) (Guidance Document) Section 6, Seismic Analysis for intermittently loaded levees1. As discussed in the ULDC, an analysis of seismic vulnerability of the levee system is to be performed for the 200-year return period ground motions. High, Medium, and Low Vulnerability classifications from the Guidance Document (URS, 2015d) will be based on the seismic deformation estimates, see Figure 1-2 included in Section 1.5.4. The steps for evaluating and classifying the levee are outlined in the SETAM in Appendix A and are described briefly below. Figure 1-3 presents a flow chart describing the seismic evaluation criteria.

1.5.1 PRELIMINARY WORK
Kleinfelder performed a review of the existing geotechnical analysis and subsurface data. During this process, seismic segment data gaps were identified and the updated peak horizontal acceleration (PHA) and magnitude values were developed.

Previous development of ground motion parameters in the area was performed by URS in 2007 as part of the Delta Risk Management Strategy (DRMS), which was updated and expanded on in 2012 by URS as part of the DWR ULE project. Updated ground motion parameters were developed following assumptions of this previous work, and detailed methodology is presented in our Seismic Evaluation Ground Motion Parameter Selection Memorandum (GMPSM) (Kleinfelder, 2023b), which is included in Appendix B. A probabilistic seismic hazard analysis was performed to determine PHA and earthquake magnitude as discussed in the GMPSM and Section 3, Ground Motion Hazard Analysis (GMHA), of this report.

1.5.2 PHASE 1: SCREENING REVIEW OF EXISTING ANALYSIS
The levees are organized by selection of “segments” instead of reaches due to the variable nature of subsurface conditions under levees. Segments may overlap multiple reaches or reaches may be 1 The ULDC requires classifying the levee as frequently loaded or intermittently loaded. A frequently loaded levee is defined in the ULDC as a levee with water at least one foot above the landside levee toe for more than 36 days in a year. As stated in the ULE GERs (URS, 2015a-c), the study area levees generally do not contain water above the landside toe for this time interval. Therefore, the levees within the study area are considered intermittently loaded for this study.
24001006.001A/SAC25R179413 Page 4 of 32 April 16, 2025
© 2025 Kleinfelder
subdivided into multiple segments. Levee segments, which were based on portions of the levees with similar soil types and liquefaction results, and analysis sections for each segment for seismic evaluation were developed for the 2015 ULE evaluations and were adopted for this study. Levee segments are shown on Figure 1-1.

The screening process was performed to identify which analysis sections were classified as Low, Medium, and High Vulnerability in 2015. All sections identified as High Vulnerability were not considered for reanalysis because they would remain High Vulnerability since the updated ground motions were slightly higher than those used for the ULE evaluations. Low and Medium Vulnerability segments were reanalyzed based on the updated ground motions described in the GMPSM in Appendix B. Analysis sections determined to be non-critical for seismic performance were not used in the current analyses and are not presented in report.

Kleinfelder performed probabilistic seismic hazard analyses at select control points in the American River South Levee System area, as discussed in the GMPSM (Kleinfelder, 2023b). Newly developed PHAs and earthquake magnitudes from these analyses for critical sections were compared to ground motion parameters from previous reports. No further analysis was required for analysis sections where any of the below conditions are true:

1. The new PHA and/or earthquake magnitude are lower than the original PHA and/or earthquake magnitude and the original analysis is determined to be adequate.

2. The original analysis determined the section is not susceptible to deformation and the new PHA and/or earthquake magnitude are not higher than the original analysis PHA and/or earthquake magnitude.

3. The analysis section is found to have High Vulnerability or Flow Failure based on the original PHA and earthquake magnitude.

1.5.3 PHASE 2: TARGETED EVALUATION
A targeted evaluation was required for critical sections (except for segments with High Vulnerability) under two conditions, as follows:

1. The original analysis classified the section as Low or Medium Vulnerability. 24001006.001A/SAC25R179413 Page 5 of 32 April 16, 2025
© 2025 Kleinfelder

2. The new earthquake magnitude and/or PHA exceeds the original magnitude/PHA used in the 2015 analysis.

High, Medium, and Low Vulnerability classifications were based on the seismic deformation estimates using the procedure presented in the Guidance Document (URS, 2015d). As explained in Section 1.5.2, all segments classified as High Vulnerability in the Phase 1 screening process were not analyzed, and the High Vulnerability classification remained unchanged for this study.

1.5.4 SEISMIC VULNERABILITY
The following steps were involved in assessing seismic vulnerability, Step numbers are associated with Key Steps described in Figure 6-1 of the Guidance Document (URS, 2015d); see Appendix C. These steps were performed for the ULE GERs for American River South (URS, 2015a), Sacramento River (URS, 2015b), and South Sacramento Streams (URS, 2015c), and were reviewed by Kleinfelder for this study. .

A flowchart summarizing these steps is included as Figure 1-3. Liquefaction analysis spreadsheets prepared for the ULE GER were provided to Kleinfelder by DWR for review.

Step 1. Kleinfelder performed a liquefaction analysis using revised PHA and earthquake magnitude values. The URS SPT-based liquefaction spreadsheets were used to delineate zones of liquefaction. These spreadsheet analyses are included as Appendix D; the original URS spreadsheets are included as Appendix E.

Step 2. The analysis cross sections developed for the 2015 ULE project were used for this study.

For selected cross sections, FOS against flow failure were estimated using residual strength for liquefiable materials and static slope stability analysis. If FOS was less than 1, the section was classified as “High Vulnerability” and no further analysis was needed.

If FOS against flow failure was greater than 1.3, the analysis section was classified as “Low Vulnerability” unless analysis for volumetric strain resulted in a higher vulnerability class.

Kleinfelder and others have previously performed extensive slope failure modeling along the levee alignments using SLOPE/W, a two-dimensional finite element computer modeling, a package included in the GEOSTUDIO software package, which was developed by Bentley Systems, Inc. Where necessary, these models were updated to the current version of GEOSTUDIO (2023.1.2) and utilized for Targeted Flow Failure analyses. Idealized soil properties were based on previous investigations and generalized parameters from the Guidance 24001006.001A/SAC25R179413 Page 6 of 32 April 16, 2025
© 2025 Kleinfelder
Document (URS, 2015d). Water surface elevations for seismic flow failure analyses were the higher of either average summer or average winter water surfaces, in accordance with the Guidance Document (URS, 2015d).

Slope failure analyses considered all potential failure modes, including:
• Waterside and landside
• Deep and shallow
• Circular and wedge-shaped
Step 3. If FOS against flow failure was between 1.0 and 1.3, a simplified seismic deformation analysis was performed on the section. This involved computing a maximum horizontal seismic coefficient (Kmax) and performing a pseudo-static stability analysis using a horizontal seismic coefficient of 50% of the maximum value. This analysis was performed using the same updated SLOPE/W models used in Step 2. If the resulting FOS was greater than 1.0, the section was classified as “Low Vulnerability”.

Yield acceleration (Ky) values were then estimated using pseudo-static analyses using the same SLOPE/W models used in Step 2. Yield acceleration was defined as the minimum horizontal acceleration resulting in a just-stable slope condition, i.e. FOS = 1.0. Yield acceleration was developed for each potential failure mode.

A Newmark-type deformation analysis was performed based on the Kmax and Ky values determined above. The freeboard loss was estimated as 70% of the Newmark displacement.

Volumetric settlement was considered for sections with potentially liquefiable soils thicker than 20 feet. Previous work performed by URS on ULE considered (N1)60-cs blow counts less than 15 as liquefiable and subject to volumetric settlement. This blow count criterion was evaluated against new research and revised, if warranted.

Seismic vulnerability classification was determined by calculating freeboard loss as the sum of Newmark-type vertical deformation and volumetric settlement (if applicable). Freeboard loss was evaluated as a percentage of levee height (as measured from hinge point on the landside toe). Engineering judgment was used to determine damage to internal levee structures, and the seismic vulnerability class was evaluated based on Table 6-1 from the Guidance Document (URS, 2015d) shown below in Figure 1-2.
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Figure 1-2: Table 6-1 from DWR Guidance Document, Section 6.4 Step 4. Advanced seismic deformation analyses as described in Appendix C only apply to frequently loaded levees and were not applicable to this study.

The stages of our evaluation were described in detail in Kleinfelder’s SETAM (KLF, 2023a) and GMPSM (KLF, 2023b), as well as Section 6 of the Guidance Document (URS, 2015d). These documents are included as Appendices A, B, and C, respectively.

1.5.5 SEISMIC DEFORMATION MODELING
Several seismic segments along major streams in this study area were identified as having High Vulnerability due to flow failure. The post-seismic slope stability failure planes in the 2015 ULE GERs are shown to extend deep into the riverbank and outward to the levee waterside. These results indicate that once a seismic event occurs, a significant amount of the levee prism and riverbank may collapse and potentially not be reusable for levee reconstruction. To support the seismic evaluation for this study area by providing more detailed conclusions about the liquefaction-induced strength loss and resulting riverbank deformation, an analysis was conducted using FLAC2D V8.0 on a critical cross section.

The levee at SREL Station 1471+30 was selected for modeling because available explorations signify the subsurface profile features the greatest thickness of liquefiable layers among the study area levees. Soils that are estimated to be potentially liquefiable were modeled using PM4Sand or PM4Silt. These allowed the model to run cyclic softening and provide a rigorous liquefaction simulation. The methodology, parameters, and results for the FLAC2D model are detailed in Appendix F, Seismic Deformation Modeling, and are presented in Section 8 of this report. 24001006.001A/SAC25R179413 Page 8 of 32 April 16, 2025
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2 GEOLOGY AND GEOMORPHOLOGY
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2.1 REGIONAL GEOLOGIC SETTING
The American River South Levee System study area is located within the southern portion of the Sacramento Valley, within the Great Valley geomorphic province. The Great Valley province is a northsouth trending 400-mile long by 50-wide alluvial plain in central California comprised of the Sacramento Valley in the north and the San Joaquin Valley in the south. The Sacramento Valley contains thousands of feet of accumulated fluvial, overbank, and alluvial fan deposits derived from erosion of the adjacent Sierra Nevada mountains to the east, northern Coast Range mountains to the west, and Klamath and Cascade mountains to the north. These deposits are primarily comprised of Quaternary and Tertiary age (present day to 56 million years ago) alluvial deposits and include clays, silts, sands, and gravels. The alluvial deposits thin out at the margins of the Great Valley province, exposing the underlying bedrock units. The Foothills Metamorphic Belt and the basement complex of the Sierra Nevada Batholith to the east are exposed along the eastern boundary of the valley. Sedimentary and mélange bedrock of the northern Coast Range mountains are exposed to the west. Meta-sedimentary, mélange, igneous, and volcanic bedrock of the Klamath and Cascade mountains are exposed to the north.

Geologic maps covering the study area on a regional scale were reviewed as a part of this study.

Published maps include:
• Wagner et al. “Geologic Map of the Sacramento Quadrangle, California. 1:250,000. Dated 1981. • Helley and Harwood. “Geologic Map of the late Cenozoic Deposits of the Sacramento Valley and Northern Sierran Foothills, California.” Sheet 1 of 5. 1:62,500. Dated 1985. • Gutierrez, C.I. “Preliminary Geologic Map of the Sacramento 30’ X 60’ Quadrangle, California,” Scale 1:100,000. Dated 2011.

Wagner et al. provides a generalized regional context of the geologic units within and surrounding the study area. Guitierrez provides an updated version of the Helley and Hardwood map with more detail of the alluvial deposits within and surrounding the study area than Wagner et al. In general, the three maps present the geologic units consistently in the vicinity of the study area. Figure 2-1 shows the study area on the Wagner et al. geologic map.
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2.2 LOCAL GEOLOGY
A review of the local geology was performed using larger scale geologic maps covering the study area and comparing to the previously discussed regional geologic maps and existing subsurface data. Based on this review the local geology at depth is summarized in the sections below.

Surficial geology maps were previously prepared by Fugro William Lettis Associates (FWLA) of the study area on the following maps.
• “Surficial Geologic Map of the American River Study Area.” Scale 1:20,000. Dated 2008. (FWLA, 2008)
• “Surficial Geologic Map of the East Side of the Sacramento River.” Scale 1:20,000. Dated 2010. (FWLA, 2010)
• “Surficial Geologic Map of the South Sacramento Streams Study Area.” Scale 1:24,000. Dated 2011. (FWLA, 2011).

The FWLA map was prepared by reviewing existing geologic maps of the area, topography, and aerial photographs from 1937. The mapping was superimposed on a modern U.S. Geological Survey topographic base map originally prepared in 1952 and revised in later years. The FWLA map provides detailed geologic mapping within the study area. Figure 2-2 shows the American River South Levee alignment plotted on the FWLA 2008 geology map; Figure 2-3 shows the Sacramento River East Levee alignment plotted on the FWLA 2010 geology map; Figure 2-4 shows the Beach Lake North Levee alignment plotted on the FWLA 2011 geology map. It should be noted that the FWLA geologic mapping occurred before field exploration was performed for the ULE project and was not reviewed/updated based on the field explorations.

2.2.1 SURFICIAL GEOLOGY
The major surficial geologic deposits within the FWLA are summarized below with the geologic unit symbols used by FWLA (2008, 2010, 2011).
• Cultural Deposits (L, RR, R, ML): Historical Levee (L), Railroad Embankment (RR), Road Embankment (R), and Made Land (ML); made of artificial fill (Circa 1937 except Made Land). The Made Land is described as fill material of local and exotic sources, sand, silt, organics, garbage, etc. Historical Levee deposits are generally mapped along the American and Sacramento Rivers. 24001006.001A/SAC25R179413 Page 10 of 32 April 16, 2025 © 2025 Kleinfelder
Railroad Embankments are mapped at the Southern Pacific Railway area near the Confluence, the Union Pacific Railroad tracks that cross American River, and the Western Pacific Railroad tracks east of the Beach Lake North Levees. Made Land and Road Embankments are mapped sporadically along and within the American River.
• Borrow Pit (BP): area mapped where the existing fill was removed as noted from the 1937 aerial photographs. The material was likely used in levee fill construction. Borrow pits are mapped sporadically along ARSL and SREL.
• Historical Overbank Deposits (Rob): sand, silt, and clay deposited during high-stage water flow overtopping channel banks. Mapped along SREL and ARSL.
• Historical Crevasse Splay Deposits (Rcs): fine to coarse sand, with minor lenses of gravel deposited from breaching of natural or artificial levees. Mapped along SREL and ARSL and within Edward’s Break Area and the Pocket area of SREL.
• Historical Distributary Fan Deposits (Rdf): sand, silt, and clay. Mapped at historical floodplain and alluvial fan deposits within the Pocket.
• Historical Channel Deposits (Rch): well-sorted sands and fine gravels. Mapped in portions at American River and BLNL.
o Historical Channel Bar Deposits (Rb): fine gravel, sand, and silt deposited at or along channel lateral margins. Mapped along portions of SREL and American River. o Historical Point Bar Deposits (Rpb): well sorted sand with minor amounts of silt and clay.

Mapped along minimal portions of American River.
• Historical Cut-off Channel (Chute) Deposits (Rcu): chutes which occur on insides of meander bends within the river channel. On the flood plain – entrenchment of overflow channels into hydraulic mining debris. Mapped along portions of ARSL. • Historical Distributary Channel Deposits (Rdc): sand, silt, clay and trace gravel; channelized flow conducting sediment to floodplain. Mapped infrequently along historic channels within Pocket and Confluence.
• Historical Overflow Channels (Rofc): vertically stratified sand, silt, and clay in floodplain channels occupied primarily when high-stage water overtops channel banks. Mapped at portions of ARSL. 24001006.001A/SAC25R179413 Page 11 of 32 April 16, 2025 © 2025 Kleinfelder
• Historical Slough Deposits (Rsl): sand, silt, and clay, fining upward, low-energy channel deposits.

Mapped north of American River.
• Historical Alluvial Deposits (Ra): undifferentiated; sand, silt, and minor lenses of fine gravel.

Mapped along American River and at Confluence.
• Holocene Overbank Deposits (Hob): sand, silt, and clay deposited during high-stage water flow overtopping channel banks. Mapped consistently along SREL within and south of The Pocket. • Holocene Crevasse Splay Deposits (Hcs): fine to coarse sand with minor lenses of gravel deposited from breaching of natural or artificial levees. Mapped sporadically in portions at SREL. • Holocene Channel Deposits (Hch): sorted sands and silts, fining upward. Mapped south of ARSL and BLNL, and east of the bends at SREL.
o Holocene Point Bars (Hpb): well-sorted sand with minor amounts of silt and clay.

Mapped within Sacramento River bend from Station 1110+00 to 1140+00. o Holocene Channel Meander Scroll Deposits (Hms): interbedded sand, silt and clay from lateral channel migration. Mapped within Sacramento River bends in Pocket area. o Holocene Channel Deposits (Qch): sorted sands and silts, fining upward. Mapped within Riverbank Formation south of ARSL and east of SREL.
• Holocene Undifferentiated Alluvial Deposits (Qa/Ha): sand, silt, and minor lenses of gravel; commonly under cultivation in 1937. Mapped in large areas inside bends of SREL, frequently at ARSL, and along channel deposits south of BLNL.
o Ha: Holocene undifferentiated alluvial deposits, probably mantled by a thin veneer of historical sediment (less than 5 feet thick). Mapped predominantly along ARSL. • Holocene Basin Deposits (Qn/Hn): fine sand, silt, and clay; under cultivation in 1937. Mapped by SREL within The Pocket (approximately 2 miles by 2 miles) and along BLNL. • Holocene Marsh Deposits (Qs/Hs): silt and clay, likely organic-rich; perennially or seasonally submerged on 1937 photography. Mapped at the Confluence of American and Sacramento Rivers.
• Modesto Formation (Qmu, Qml): Late Pleistocene (estimated 12,000 to 45,000 years of age) alluvium consisting of gravel, sand, silt, and clay; Upper Modesto (Qmu) typically unconsolidated 24001006.001A/SAC25R179413 Page 12 of 32 April 16, 2025 © 2025 Kleinfelder
and dense while the lower member (Qml) is typically unconsolidated to semi-consolidated and dense to very dense; very dense and/or semi-consolidated layers of the Modesto Formation may be identified as “hardpan.” Mapped primarily south of ARSL; small portion mapped east of The Pocket.
• Riverbank Formation (Qru, Qrl): Mid-Pleistocene (estimated 130,000-450,000 years of age) alluvial fan consisting of gravel, sand, silt, and clay containing high-pedogenic silt and clay content and reddish hues reflective of its relative age; upper Riverbank Formation (Qru) typically semi-consolidated to consolidated while the lower (Qrl) typically consolidated and very dense; the very dense and/or consolidated layers of this formation locally referred to as “hardpan.” Mapped east of SREL and BLNL.

2.2.2 GENERALIZED NEAR SURFACE STRATIGRAPHY
Near surface stratigraphy (approximately upper 100 feet) was based on review and interpretation of geology publications, historical aerial photographs, current and historical topography, and existing subsurface data. The following provides a generalized stratigraphic description beginning from the bottom of the section along the study area levees.

The Early Pleistocene Turlock Lake Formation underlies the study area levees at depth. The Turlock Lake Formation is an alluvial fan deposit mapped as exposed at the surface generally to the east of Watt Avenue where it is topographically higher than the Riverbank Formation. The Turlock Lake Formation generally consists of weathered sands with some gravels and silts.

The Pleistocene Riverbank Formation overlies the Turlock Lake Formation. Generally, the Riverbank Formation is an alluvial fan deposit mapped as exposed at the surface generally west of Watt Avenue and laterally continuous across the study area. The Riverbank Formation was gradually incised by historical and active streams to create current day conditions. The Riverbank Formation consists of predominately stiff to indurated fine-grained soils with localized channels of sands and gravels.

The Late Pleistocene Modesto Formation overlies the Riverbank Formation and is generally local to the active and historical streams and American River within the study area. The Modesto Formation varies in thickness extending to approximately 30 feet and consists of a wide range of materials including soft to indurated fine-grained soils as well as gravels and cobbles along the American River. Additionally, this unit has been significantly eroded and is laterally discontinuous. 24001006.001A/SAC25R179413 Page 13 of 32 April 16, 2025 © 2025 Kleinfelder
Holocene and Recent fluvial deposits overlay the Riverbank and Modesto Formations along the study area streams and American River. The areas are generally blanketed by fine-grained soils indicative of lower energy overbank and basin deposits. The fine-grained soils are dissected by channel and crevasse deposits generally consisting of soils with higher percentage of sand.

The levees in each study area were constructed on top of the native soils in the mid-1900s generally using non-modern-day conventional construction methods and testing. The levee embankments generally consist of sand, silty sand, and clayey sands. Since initial construction, SAFCA and USACE have built flood protection improvements to the levees to strengthen them over time, including seepage cutoff walls, floodwalls, and embankments of engineered fill.

2.3 SEISMOTECTONIC SETTING
The project is located in the Western United States (WUS) in the transform plate boundary region between the Pacific Plate (transitioning northwest) and the North American Plate. The site lies within the Sierra Nevada-Great Valley block (a.k.a., the Sierra Nevada microplate, or SNGV) which generally is thought to act as an independent block that has ‘tilted’ westward. The SNGV block is bounded on its eastern edge by a zone of faults known as the Walker Lane Belt, beyond which is the crustal extensional region of the Northern Basin and Range. Further afield in the northwestern portion of the state and extending northward to the Pacific Northwest, the Juan de Fuca plate is currently subducting below the North American plate in a region known as the Cascadia Subduction Zone (Humphreys and Coblentz, 2007; Unruh and Humphrey, 2003, 2017).

Regional stress buildup due to the northwestern movement of the Pacific Plate is primarily released through displacement along faults within the San Andreas fault system (e.g., San Andreas fault, Hayward fault, etc.) and to a lesser extent by displacements along faults within the Walker Lane Belt. Crustal extension of the Northern Basin and Range has led to the development of stress in the east-west direction and caused development of an extensive system of faults within the Northern Basin and Range (Fey and Humphreys, 2008; Field et al., 2013). These faults and other regional seismic sources are shown on Figures 3 and 4 of the GMPSM (Kleinfelder, 2023b) in Appendix B. 24001006.001A/SAC25R179413 Page 14 of 32 April 16, 2025 © 2025 Kleinfelder
3 GROUND MOTION HAZARD ANALYSIS
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3.1 SEISMIC HAZARD ANALYSIS
Kleinfelder performed a site-specific probabilistic seismic hazard analysis (PSHA) for five control points within the American River South Levee System area as shown on Figure 1-1. A detailed description of the probabilistic seismic hazard analysis performed for this project is presented in the GMPSM (Kleinfelder, 2023a) in Appendix B.

To account for site effects and basin effects, the site parameters in Table 3.1 were evaluated. Because ground motions were evaluated at stiff soil condition, the Vs30 (average shear wave velocity in the upper 100 feet/30 meters) value was taken as 335 m/s. Z1.0 and Z2.5 were estimated utilizing the correlations developed for the NGA West 2 project, with justification per Peterson et al. 2019.

For the Ground Motion Models (GMMs), Kleinfelder used four of the Next Generation Attenuation (NGA) West 2 relationships including Abrahamson et al. (2014), Boore et al. (2014), Chiou and Youngs (2014), and Campbell and Bozorgnia (2014) with equal weights applied for all crustal faults (e.g. reverse, strike-slip, normal) included in the fault model. The Idriss (2014) model has not been used as it is not valid for the VS30 used in our study and also for the larger distances used in this study (e.g. more than 150 km). The far-field subduction events (e.g. from Cascadia megathrust) were modeled using the relationships of Atkinson and Macias (2009), Abrahamson et al. (2016), and Zhao et al. (2006) with equal weights applied, except that for slab events the Atkinson and Macias (2009) relationship was excluded.

Spectral acceleration values are obtained by averaging the individual hazard results. These GMM’s provide ‘mean’ (RotD50) values of ground motions associated with magnitude, distance, site soil conditions, and mechanism of faulting.

Table 3.1
Seismic Hazard Analysis Site Parameters
Point ID Latitude Longitude VS30
(m/s)
Z1.0
(km)
Z2.5
(km)
Confluence 38.5982 -121.5087
335 0.428 1.55
American River East 38.5921 -121.3344
Little Pocket 38.5293 -121.5288
Pocket 38.4989 -121.5578
SREL South 38.4447 -121.5002
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3.1.1 SEISMIC ANALYSIS RESULTS
Kleinfelder calculated the probabilistic geometric mean Peak Horizontal Acceleration (PHA) values and deaggregation results at five points around the Natomas analysis area (see Figure 1-1). The PHA has a 200-year return period and is listed in Table 3.2 along with the corresponding PHA value estimated from the Seismic Hazard Map in the 2015 ULE American River, Sacramento River, and South Sacramento Streams GERs (URS, 2015a-c).

Table 3.2
Probabilistic Peak Horizontal Acceleration and Controlling Earthquake Magnitude Point ID
PHA (g) Deaggregation Results
(KLF, 2023) (URS, 2015) MW Distance (km)
Confluence 0.14 0.146 6.8 67
American River East 0.12 0.126 6.8 81
Little Pocket 0.14 0.152 6.7 63
Pocket 0.15 0.163 6.7 60
SREL South 0.15 0.148 6.7 62
The new PHA values calculated for each ARSLS analysis control point corresponding have very small differences from the 2015 ULE and are generally slightly lower than the 2015 ULE values. However, the 2015 ULE performed liquefaction analyses used an earthquake magnitude of 6.5; Kleinfelder’s deaggregation analyses resulted in earthquake magnitudes of 6.8 for the northmost control points (Confluence and American River East) and 6.7 for the southmost points (Little Pocket, Pocket, and SREL South). Hence, Kleinfelder performed liquefaction analyses using the original PHA values and the 2023 KLF earthquake magnitudes. The old PHA values were used in the evaluation as the new values are not significantly different from the old values which are slightly conservative. Refer to Section 4.1.1 for clarification on which segments used earthquake magnitude 6.7 and which used 6.8. 24001006.001A/SAC25R179413 Page 16 of 32 April 16, 2025 © 2025 Kleinfelder
4 PREVIOUS EVALUATION
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4.1 SUMMARY
The 2015 URS Geotechnical Evaluation Reports for the American River (URS, 2015a), Sacramento River (URS, 2015b), and South Sacramento Streams (URS, 2015c) study areas presented Seismic Vulnerability Evaluations in accordance with the requirements developed for ULE. SPT-based liquefaction analyses were performed to identify potentially liquefiable and non-liquefiable layers. These results were used, where applicable, to perform post-seismic stability and deformation analyses and classify the seismic vulnerability of each levee segment.

4.1.1 GENERAL
Kleinfelder reviewed the 2015 URS Seismic Vulnerability Analyses for the levee segments as part of the Phase 1 Screening Analysis. Segments with High Vulnerability classifications did not receive reanalysis.

Any segments noted as having Low or Medium Vulnerability and containing at least one liquefiable layer required a targeted re-evaluation and are shaded gray in Table 4.1. Low or Medium Vulnerability segments noted as non-liquefiable in 2015 were still reanalyzed because the earthquake magnitudes were updated; refer to Note 1 in Table 4.1. Segment ARSL-2 (Sutter’s Landing Regional Park, formerly the 28th Street Landfill) was not evaluated because no levee was present due to high ground on the landside (URS, 2015a).

Table 4.1
Phase 1 – Seismic Vulnerability Results Screening
Segment ID Station Start Station End 2015 URS
Vulnerability
Contains
Potentially
Liquefiable Layer
Additional
Analysis Required
American River South Levee
ARSL-1 1000+00 1135+00 High Yes No
ARSL-2 1135+00 1195+00 High Ground, No Analysis Needed
ARSL-3 1195+00 1335+86 High Yes No
ARSL-4 1335+86 1381+93 Low No1 Yes
ARSL-5 1381+93 1431+25 High Yes No
ARSL-6 1431+25 1635+49 Low No1 Yes
Sacramento River East Levee
SREL-1 1000+00 1019+00 High Yes No
SREL-2 1019+00 1086+00 High Yes No
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Segment ID Station Start Station End 2015 URS
Vulnerability
Contains
Potentially
Liquefiable Layer
Additional
Analysis Required
SREL-3 1086+00 1178+00 High Yes No
SREL-4 1178+00 1214+00 High Yes No
SREL-5 1214+00 1245+00 High Yes No
SREL-6 1245+00 1286+00 High Yes No
SREL-7 1286+00 1425+00 High Yes No
SREL-8 1425+00 1671+00 High Yes No
SREL-9 1671+00 1707+50 Low No1 Yes
SREL-10 1707+50 1770+00 High Yes No
Beach Lake North Levee
BLNL-1 987+18 993+18 High Yes No
BLNL-2 993+18 1004+40 Low Yes Yes
BLNL-3 1004+40 1034+10 High Yes No
BLNL-4 1034+10 1117+55 Low Yes Yes
BLNL-5 1117+55 1136+74 High Yes No
Note:
1 – The 2015 evaluations noted that based on the evaluation of available explorations, these segments do not contain liquefiable or soft soil (non-free draining with estimated shear strength < 500 psf) layers. However, because of the changes to earthquake magnitude, the SPT-based liquefaction spreadsheet calculations were still updated to check if any layers that became Less Likely Liquefiable or Likely Liquefiable could be considered representative of the entire segment.

The earthquake magnitude used to update the 2015 SPT-based liquefaction calculations was based on the proximity of each segment to the control points shown on Figure 1-1. Earthquake magnitude 6.7 was used for all Beach Lake North Levee segments and Sacramento River East Levee Segments 4 through 10.

Earthquake magnitude 6.8 was used for all American River South Levee segments and Sacramento River East Levee Segments 1 through 3.

The liquefaction analyses for the Low Vulnerability segments were revised using earthquake magnitude

6.7 or 6.8 instead of 6.5. No other parameters of the analyses were changed and no additional borings were analyzed. The revised liquefaction analyses are included in Appendix D. The original URS liquefaction spreadsheets are included as Appendix E.

4.2 SEISMIC ANALYSIS WATER SURFACE ELEVATIONS
Per the Guidance Document (URS, 2015d), seismic vulnerability analyses were performed using the higher of the average summer or winter Water Surface Elevations (WSE) at each ULDC segment.

Kleinfelder assessed the applicability of the average WSEs used for the 2015 liquefaction calculations for the updated calculations. The California Department of Water Resources (DWR) provides a database of groundwater well measurements across the Sacramento Valley. For the updated calculations, data from wells located near a ULDC segment were evaluated for further analysis. Upon review of the available 24001006.001A/SAC25R179413 Page 18 of 32 April 16, 2025 © 2025 Kleinfelder
information, the mean winter and summer groundwater elevations were lower than those used for the seismic analyses in 2015. Generally, mean groundwater elevations from the past ten years were lower than those used in the liquefaction analyses in the same area by approximately 10 feet, possibly due to droughts and other seasonal factors. Therefore, it was decided to continue using the same WSEs from 2015 study because they are higher in elevation and would provide conservative results for liquefaction. 24001006.001A/SAC25R179413 Page 19 of 32 April 16, 2025 © 2025 Kleinfelder
5 CURRENT EVALUATION
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5.1 SEISMIC EVALUATION SEGMENT SELECTION
Of the six seismic segments for American River South Levee, the 2015 GER classified two of them as Low Vulnerability: ARSL-4 and ARSL-6 (URS, 2015a). Of the ten seismic segments for Sacramento River East Levee, the 2015 GER classified one of them as Low Vulnerability: SREL-9 (URS, 2015b). Of the five seismic segments for Beach Lake North Levee, the 2015 GER classified two of them as Low Vulnerability: BLNL-2 and BLNL-4 (URS, 2015c). In total, five segments required targeted evaluation in this SPSR.

5.1.1 LIQUEFACTION ANALYSIS OF ULDC SEGMENTS
The 2015 URS evaluations produced SPT-Based Liquefaction Analysis Excel spreadsheets for multiple borings corresponding to the ULDC segments. The results of these analyses justified the stratigraphy and strengths of the Likely Liquefiable layers used for the 2015 post-seismic models. These layers are summarized in Table 5.1.1.

Table 5.1.1
ARSLS - 2015 Post-Seismic Model Liquefiable Layers
Segment
ID
Analysis
Station
Layer
Classification
Elevation
Boundaries of
Layer (ft)
Layer
Thickness (ft)
Median
(N1)60-cs-Sur
Residual
Undrained
Strength (psf)
ARSL-4 No Liquefiable or Soft Soil Layers in 2015 Analysis1 ARSL-6 No Liquefiable or Soft Soil Layers in 2015 Analysis1 SREL-9 No Liquefiable or Soft Soil Layers in 2015 Analysis1 BLNL-2 998+33
Likely Liquefiable

0.4 to -1.4 (WS)

0.4 to -3.4 (LS)
2 (WS)
4 (LS)
10 240
Likely Liquefiable -22.6 to -32.6 10 10 240
BLNL-4 1077+50
Likely Liquefiable

2.0 to 0.5 (WS)

4.0 to -0.5 (LS)

1.5 (WS)

4.5 (LS)
10 240
Likely Liquefiable -5.0 to -8.5 3.5 14.5 550
Notes:
1 – The 2015 evaluations noted that based on the evaluation of available explorations, these segments do not contain liquefiable or soft soil (non-free draining with estimated shear strength < 500 psf) layers. The SPT-based liquefaction spreadsheet calculations were still updated using the new magnitudes to check if any layers that became Less Likely Liquefiable or Likely Liquefiable could be considered representative of the entire segment.
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The liquefaction analyses were updated using the updated GMHA deaggregated earthquake magnitudes as described in Section 3.1.1. Earthquake magnitude 6.7 was used for both Beach Lake North Levee segments and Sacramento River East Levee Segment 9. Earthquake magnitude 6.8 was used for the American River South Levee segments. The spreadsheet calculations are included in Appendix D:

Updated SPT-Based Liquefaction Calculations for Targeted Segments.

The borings for the targeted evaluation segments are listed in Table 5.1.2. The Factors of Safety (FOS) of some potentially liquefiable layers decreased from above to below 1.25 (“Non-Liquefiable” to “Less Likely Liquefiable”), and some decreased from above to below 1.0 (“Less Likely Liquefiable” to “Likely Liquefiable”). Table 5.1.2 notes borings where at least one layer changed in one of these ways.

Table 5.1.2
ARSLS - Liquefaction Layer Changes for Targeted Segments Segment ID Station
Start
Station
End Magnitude Liquefaction Analysis Boring (Station)
Liquefiable Layer
Classification
Change
American River South Levee
ARSL-4 1335+86 1381+93 6.8 2F-11-160
(1359+23)
No
ARSL-6 1431+25 1635+49 6.8
WRDA_2F-11-03
(1469+25)
Yes
2F-97-31
(1544+03)
No
ARFCD-ARS-B-7
(1611+00)
No
Sacramento River East Levee
SREL-9 1671+00 1707+50 6.7
2F-05-G7-1
(1678+85) Yes
2F-05-G7-2
(1692+29) No
WM9_017B
(1701+90) No
24001006.001A/SAC25R179413 Page 21 of 32 April 16, 2025 © 2025 Kleinfelder
Segment ID Station
Start
Station
End Magnitude Liquefaction Analysis Boring (Station)
Liquefiable Layer
Classification
Change
Beach Lake North Levee
BLNL-2 993+18 1004+40 6.7 2F-10-07
(998+33) No
BLNL-4 1034+10 1117+55 6.7
2F-10-01
(1044+56) Yes
2F-10-02
(1044+70) No
B-2
(1074+50) Yes
B-12
(1088+61) No
Because the liquefiable layer classifications did not change for Segment ARSL-4, it remains classified as Low Vulnerability and additional analysis was not necessary. Although the layer classifications for BLNL-2 did not change either, based on how the 2015 evaluation was conducted, its classification as Low Vulnerability is dependent on BLNL-4 remaining Low Vulnerability (refer to Section 5.2).

In the updated liquefaction calculations, specific layers for ARSL-6, SREL-9, and BLNL-4 became Less Likely Liquefiable or Likely Liquefiable. Table 5.1.3 describes the affected layers and their new Factors of Safety against liquefaction. Seismic vulnerability classifications are described in Section 5.2.

Table 5.1.3
ARSLS - Liquefiable Layer Classification and Factor of Safety Changes for Targeted Segments Segment
ID Boring (Station)
Sample
Elevation
(feet)
Layer Thickness
(feet)
Liquefaction FOS
(2015, Mw = 6.5)1
Liquefaction
FOS
(2025)
1 ARSL-6
WRDA_2F-11-03
(1469+25)

24.0 5.0 1.35 1.21
SREL-9
2F-05-G7-1
(1678+85)
-19.7 3.0 1.32 1.24
-22.7 3.0 1.25 1.17
BLNL-4
2F-10-01
(1044+56) -10.4 2.0 1.06 1.00
B-2
(1074+50) -20.5 5.0 1.03 0.96
Note: 1 – Yellow FOS indicates layer is “Less Likely Liquefiable,” Red FOS indicates layer is “Likely Liquefiable.” Magnitude 6.8 used for ARSL-6 liquefaction analysis, magnitude 6.7 used for SREL-9 and BLNL-4 analysis. 24001006.001A/SAC25R179413 Page 22 of 32 April 16, 2025 © 2025 Kleinfelder
Vertical settlement calculations are not required because the liquefiable layers do not exceed 20 feet in thickness (URS, 2015d). The updated liquefaction spreadsheet calculations are included in Appendix D.

5.2 VULNERABILITY CLASSIFICATIONS FOR TARGETED SEGMENTS As stated in Table 5.1.1, the previous evaluation for ARSL and SREL used the lack of liquefiable and soft soil layers to justify the Low Vulnerability classification for segments ARSL-4, ARSL-6, and SREL-9.

However, the updated SPT-based liquefaction calculations resulted in some layers to be Less Likely Liquefiable, which were earlier classified as non-liquefiable, for certain borings within segments ARSL-6 and SREL-9. Sections 5.2.1 through 5.2.3 discuss how the updated analysis affects the seismic vulnerability classifications for the targeted ARSL and SREL segments.

For the targeted BLNL segments, the previous evaluation analyzed BLNL-4 before BLNL-2. This was because the segments share similar geometry, but the upper Likely Liquefiable layer for BLNL-4 was at a higher elevation than BLNL-2 (refer to Table 5.1.1), making it more susceptible to seismic vulnerability.

The 2015 post-seismic slope stability analyses performed for BLNL-4, as shown by the results in Table

5.2.1 below, have factors of safety greater than 1.0, so the segment was classified as Low Vulnerability.

Because BLNL-2 had similar geometry and residual strengths with deeper liquefiable layers than BLNL-4, it was also classified Low Vulnerability. Section 5.2.4 describes how the updated liquefaction calculations affect BLNL-4, then the results are used in Section 5.2.5 to classify BLNL-2.

Table 5.2.1
ARSLS - 2015 BLNL-4 Post-Seismic Stability Analysis Factors of Safety Segment
ID
Analysis
Station
Landside
Global FOS
Landside
Block FOS
Waterside
Global
FOS
Waterside
Block FOS
2015 Seismic
Vulnerability
BLNL-4 1077+50 1.93 1.79 2.60 2.31 Low

5.2.1 SEGMENT ARSL-4
As described in Table 5.1.1, no changes in liquefaction classification occurred for any layers in the borings analyzed for ARSL-4. The results of the analysis from 2015 can therefore remain the same:

Segment ARSL-4 is classified as Low Vulnerability.
24001006.001A/SAC25R179413 Page 23 of 32 April 16, 2025 © 2025 Kleinfelder

5.2.2 SEGMENT ARSL-6
Segment ARSL-6 features a levee crown width of 15 feet, waterside slope dimensions 3H:1V, landside slope dimensions 2H:1V, and levee height 6 feet according to the American River GER (URS, 2015a). The GER states that based on evaluation of available explorations, ARSL-6 does not contain liquefiable layers except for a thin, isolated Likely Liquefiable layer 45 feet below the landside toe. This layer was assumed to have a negligible effect due to its depth and limited extent; additionally, the SPT-based liquefaction analyses did not show this layer as Likely Liquefiable, so it was assumed to not be representative of the segment.

As shown in Table 5.1.3, the layer at elevation 24.0 feet at Station 1469+25 changed from nonliquefiable to Less Likely Liquefiable using the updated magnitude. However, based on the layer properties and comparison to nearby borings, this layer is not considered representative of ARSL-6. As shown in the calculation for WRDA_2F-11-03 in Appendix D, the layer still has low potential to liquefy because its factor of safety is 1.21, its fines content is 41% silts, and its (N1)60-cs-Sur value is 16.

Additionally, the other liquefaction calculations for ARSL-6 have gravelly layers at elevation 24.0 with (N1)60-cs-Sur values exceeding 70. Assuming the FOS 1.21 layer represents the entire segment would be a very conservative assumption. Because this layer is an outlier with little risk of liquefying, the general assumption of no liquefiable layers in the segment is still valid.

As such, Segment ARSL-6 is classified as Low Vulnerability.

5.2.3 SEGMENT SREL-9
The Sacramento River GER (URS, 2015b) states that based on evaluation of available explorations, SREL9 does not contain liquefiable or soft soil layers. In general, the levee crown is at elevation 32 feet and the landside levee toe is at elevation 20 feet throughout the segment.

As shown in Table 5.1.3, the layers at elevations -19.7 and -22.7 feet at Station 1678+85 changed from non-liquefiable to Less Likely Liquefiable using the updated earthquake magnitude. However, similarly to the changes in ARSL-6, these changes would not affect the overall classification. The layers have low potential to liquefy with factors of safety 1.24 and 1.17. Additionally, the other liquefaction calculations for SREL-9 have clayey layers at elevation -20.0, so it would be very conservative to assume the Less Likely Liquefiable layers represent the entire segment. Finally, these layers are over 40 feet below the landside toe; although they are still within the liquefaction analysis zone, they are unlikely to affect 24001006.001A/SAC25R179413 Page 24 of 32 April 16, 2025 © 2025 Kleinfelder
levee stability at this depth, especially with FOS still above 1.0. Because the layers are outliers with little risk of liquefying, the general assumption of no liquefiable layers in the segment is still valid.

As such, Segment SREL-9 is classified as Low Vulnerability.

5.2.4 SEGMENT BLNL-4
The South Sacramento Streams GER (URS, 2015c) notes that levee geometry varies across the span of Segment BLNL-4. The segment features a levee crown width of 15 to 25 feet, waterside slope dimensions 2H:1V to 4H:1V, landside slope dimensions 2H:1V to 3H:1V, and levee height 9 to 20 feet (URS, 2015c). The 2015 post-seismic stability analysis was modeled near the midpoint of the segment at Station 1077+50 with crown width 16 feet, waterside slope 3H:1V, landside slope 2.5H:1V, and levee height 12 feet.

As Table 5.2.1 shows, the four post-seismic stability FOS results exceeded 1.0. The analysis diagram in the GER shows all four critical failure planes extending no further than the bottom of the upper liquefiable layer: elevation 0.5 feet on the waterside, elevation -0.5 feet on the landside. As such, the updated liquefaction calculations needed to confirm this upper liquefiable layer did not increase in thickness, or the analysis would become outdated. Additionally, to confirm the failure planes remain above elevation -0.5 feet, any liquefiable layers located at lower elevations should equal or exceed the 550 psf ((N1)60-cs-Sur = 14.5) residual undrained strength of the lower liquefiable layer, assuming they are representative of the whole segment.

As shown in Table 5.1.3, the layer at elevation -10.4 feet at Station 1044+56 changed from Less Likely Liquefiable to Likely Liquefiable using the updated magnitude. This is located below the lower liquefiable layer modeled in the GER. This layer has classification SM and a (N1)60-cs-Sur value of 18. Using data from the available borings, the analysis in the GER calculated the median (N1)60-cs-Sur value from elevation -5.0 to -14 feet as 14.5. Based on these values, the updated layer would have very high residual undrained shear strength and would not have less strength than the non-liquefiable SP-SM layer modeled on the cross section. As such, the Likely Liquefiable layer at elevation -10.4 feet does not need to be modeled on an updated cross section.

Additionally, the layer at elevation -20.5 feet at Station 1074+50 changed from Less Likely Liquefiable to Likely Liquefiable using the updated earthquake magnitude. This layer has soil classification of SP-SM and a (N1)60-cs-Sur value of 17. As with the elevation -10.4 feet layer, the residual undrained shear strength is high enough to not affect the analysis model. The layer is also over 30 feet beneath the landside toe; 24001006.001A/SAC25R179413 Page 25 of 32 April 16, 2025 © 2025 Kleinfelder
since the failure planes already did not pass through a liquefiable layer with (N1)60-cs-Sur value 14.5 less than 20 feet beneath the landside toe, they would not likely pass through this layer either.

Because the new Likely Liquefiable layers had lower elevations and higher strengths than the liquefiable layers in the 2015 analysis, they were unlikely to affect the post-seismic stability results. As such, the original FOS results remain valid for the segment. Segment BLNL-4 remains classified as Low Vulnerability.

5.2.5 SEGMENT BLNL-2
As described in Table 5.1.1, no changes in liquefaction classification occurred for any layers in the borings analyzed for BLNL-2. The previous classification for BLNL-2 was justified using the classification for BLNL-4, as described in Section 5.2. Since Segment BLNL-4 is classified as Low Vulnerability, and BLNL-2 has similar and less vulnerable geometry, Segment BLNL-2 is classified as Low Vulnerability.

5.3 SEISMIC DEFORMATION MODELING RESULTS
As discussed in Section 1.5.5, many seismic segments in this study area were identified as having High Vulnerability due to large deformations and/or flow failure. To investigate the magnitude of potential flow failure and whether the riverbank and levee may be damaged to the point where levee in-place reconstruction may be affected, an advanced seismic analysis was conducted on a critical cross section at Station 1471+30. The results of the FLAC2D modeling show generation of excess porewater pressures and liquefaction initiation in the levee foundation soils, primarily at the waterside toe. The analysis included simulated shaking and post-shaking where excess porewater pressures were dissipated until model displacements had ceased. The resulting maximum deformations expected at the levee crest are estimated up to 3 feet vertically downwards and laterally towards the waterside. Based on the modeling results, significant levee damage may occur as a result of liquefaction and lateral spreading; however, complete riverbank collapse is not anticipated, and repair/reconstruction of the levee should be possible within the existing levee footprint. See Appendix F for additional details and results of the modeling.

It should be noted the FLAC analyses indicate that the evaluated cross sections are marginally stable and along with modeling uncertainties, particularly the uncertainty in earthquake ground motions and the natural variation of subsurface soils, present the potential for large increases in the estimated displacements, and it may be possible that greater displacements than the estimated values presented above could occur. While large-scale repairs are likely, it is anticipated that based on the results of the 24001006.001A/SAC25R179413 Page 26 of 32 April 16, 2025 © 2025 Kleinfelder
FLAC analysis, it is likely the levee easement and riverbank will be available for repair work and temporary/permanent levee construction.
24001006.001A/SAC25R179413 Page 27 of 32 April 16, 2025 © 2025 Kleinfelder
6 SEISMIC PERFORMANCE
_____________________________________________________________________

6.1 SUMMARY
Five Low Vulnerability segments in the American River South Levee System levee region were selected for further analysis using the results of Kleinfelder’s GMHA. Kleinfelder performed liquefaction analyses using updated earthquake magnitudes Mw = 6.7 and 6.8 and identified segments with additional layers that became less likely or likely liquefiable. Based on further investigation into each segment, Kleinfelder concluded that the five segments remain Low Vulnerability regarding seismic hazards. The seismic vulnerability for the ARSLS levees remains the same as the 2015 URS analysis. Segments and their seismic vulnerability classifications are listed in Table 6.1 and are shown on Figure 6-1.

Table 6.1
Seismic Vulnerability Classifications for American River South Levee System Levees Segment ID Station Start Station End 2015 Seismic
Vulnerability
2025 Seismic
Vulnerability
American River South Levee
ARSL-1 1000+00 1135+00 High High
ARSL-2 1135+00 1195+00 N/A, no levee
ARSL-3 1195+00 1335+86 High High
ARSL-4 1335+86 1381+93 Low Low
ARSL-5 1381+93 1431+25 High High
ARSL-6 1431+25 1635+49 Low Low
Sacramento River East Levee
SREL-1 1000+00 1019+00 High High
SREL-2 1019+00 1086+00 High High
SREL-3 1086+00 1178+00 High High
SREL-4 1178+00 1214+00 High High
SREL-5 1214+00 1245+00 High High
SREL-6 1245+00 1286+00 High High
SREL-7 1286+00 1425+00 High High
SREL-8 1425+00 1671+00 High High
SREL-9 1671+00 1707+50 Low Low
SREL-10 1707+50 1770+00 High High
Beach Lake North Levee
BLNL-1 987+18 993+18 High High
BLNL-2 993+18 1004+40 Low Low
BLNL-3 1004+40 1034+10 High High
BLNL-4 1034+10 1117+55 Low Low
BLNL-5 1117+55 1136+74 High High
24001006.001A/SAC25R179413 Page 28 of 32 April 16, 2025 © 2025 Kleinfelder
7 LIMITATIONS
____________________________________________________________________________ Information contained in this data report is based on our field observations, subsurface explorations completed by Kleinfelder and others, laboratory tests completed by Kleinfelder and others, and our present knowledge of the existing levee conditions. The conclusions and opinions contained in this report are also based on the assumption that information provided by the Client and/or that is referenced in this report is accurate and correct and can be relied upon. It is possible that soil conditions, including groundwater levels, could vary between or beyond the points explored.

The information, including graphic representations attached to this report, have been compiled from a variety of sources as referenced herein and are subject to change without notice. Kleinfelder makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness, or rights to the use of the information presented in this data report. These documents are not intended for use as land survey products, nor are they designed or intended as construction design documents. The use or misuse of the information contained on these graphic representations is at the sole risk of the party using or misusing the information.

We have prepared this data report in substantial accordance with the generally accepted geotechnical engineering practice as it exists in the site area at the time of our study. No warranty, express or implied, is provided. Land use, site conditions (both on site and off site), or other factors may change over time, and additional work may be required with the passage of time. Any party other than the client who wishes to use this report shall notify Kleinfelder of such intended use. Based on the intended use of the report, Kleinfelder may require that additional work be performed and that an updated report be issued. Non-compliance with any of these requirements by the client or anyone else will release Kleinfelder from liability resulting from the use of this report by any unauthorized party. 24001006.001A/SAC25R179413 Page 29 of 32 April 16, 2025 © 2025 Kleinfelder
8 REFERENCES
____________________________________________________________________________ Abrahamson, N., Gregor, N., Addo, K. (2016). BC Hydro Ground Motion Prediction Equations for Subduction Earthquakes. Earthquake Spectra, Volume 32, Issue 1, pp. 23-44.

Abrahamson, N.A., Silva, W.J., and Kamai, R. (2014). “Summary of the ASK14 Ground Motion Relation for Active Crustal Regions.” Earthquake Spectra, Vol. 30, No. 3, pp. 1025-1056.

Atkinson, G.M., and Macias, M. (2009). Predicted Ground Motions for Great Interface Earthquakes in the Cascadia Subduction Zone. Bulletin of the Seismological Society of America, V. 99, No. 3, pp. 1552-1578.

Boore, D.M., Stewart, J.P., Seyhan, E., and Atkinson, G. (2014). “NGA-West2 Equations for Predicting PGA, PGV, and 5% damped PSA for Shallow Crustal Earthquakes.” Earthquake Spectra, Vol. 30, No. 3, pp. 1057-1086.

California Department of Water Resources (DWR) (2012). Urban Levee Design Criteria.

Campbell, K.W., and Bozorgnia, Y. (2014). “NGA-West2 Ground Motion Model for the Average Horizontal Component of PGA, PGV, PGD and 5% Damped Linear Elastic Response Spectra.” Earthquake Spectra, Vol. 30, No. 3, pp. 1087-1116.

Cetin et al. (2004). “Standard Penetration Test-Based Probabilistic and Deterministic Assessment of Seismic Soil Liquefaction Potential,” Journal of Geotechnical and Geoenvironmental Engineering, Volume 130, Issue 12, ASCE, dated December 2004.

Chiou, B.S., and Youngs, R.R. (2014). “Update for the Chiou and Youngs NGA Model for the Average Horizontal Component of Peak Ground Motion and Response Spectra.” Earthquake Spectra, Vol. 30, No. 3, pp. 1117-1154.

Fey, N., Humphreys, E., 2008, Forces Acting on the Sierra Nevada Block and Implications for the Strength of the San Andreas Fault System and the Dynamics of Continental Deformation in the Western United States. Journal of Geophysical Research, Vol. 113, B 12415.

Field, E.H., Biasi, G.P., Bird, P., Dawson, T.E., Felzer, K.R., Jackson, D.D., Johnson, K.M., Jordan, T.H., Madden, C., Michael, A.J., Milner, K.R., Page, M.T., Parsons, T., Powers, P.M., Shaw, B.E., Thatcher, W.R., Weldon, R.J., II, and Zeng, Y. (2013). The Uniform California Earthquake Rupture 24001006.001A/SAC25R179413 Page 30 of 32 April 16, 2025 © 2025 Kleinfelder
Forecast, Version 3 (UCERF 3), USGS Open File Report 2013-1165, CGS Special Report 228, Southern California Earthquake Center Publication 1792, http://pubs.usgs.gov/of/2013/1165/.

Fugro William Lettis & Associates (FWLA 2008). “Surficial Geologic Map of the American River Study Area.” Scale 1:20,000. Dated 2008.

Fugro William Lettis Associates (FWLA 2010). “Surficial Geologic Map of the East Side of the Sacramento River.” Scale 1:20,000. Dated 2010.

Fugro William Lettis Associates (FWLA 2011). “Surficial Geologic Map of the South Sacramento Streams Study Area.” Scale 1:24,000. Dated 2011.

Gutierrez, C. I. (2011). “Preliminary Geologic Map of the Sacramento 30’ x 60’ Quadrangle, California,” California Geological Survey, Preliminary Geologic Maps PGM-11-06 (1:100,000 scale).

Hatanaka, M., and Uchida, A. (1996). “Empirical Correlation Between Penetration Resistance and Internal Friction Angle of Sandy Soils,” Soils and Foundations, ASCE, Vol. 36, No. 4, pp. 1-9.

Helley, E. J., and Harwood, D. S. (1985). “Geologic Map of the Late Cenozoic Deposits of the Sacramento Valley and Northern Sierran Foothills, California,” U. S. Geological Survey Miscellaneous Field Studies Map MF-1790.

Humphreys, E., and Coblentz, D. (2007). North American Dynamics and Western U.S. Tectonics.

American Geophysical Union, Reviews of Geophysics, 45, RG3001.

Idriss, I.M. (2014). “An NGA-West2 Empirical Model for Estimating the Horizontal Spectral Values Generated by Shallow Crustal Earthquakes.” Earthquake Spectra, Vol. 30, No. 3, pp. 1155-1177.

Jennings, C.W., Strand, R.G., and Rogers, T.H. (1977), Geologic Map of California: California Division of Mines and Geology Geologic Data Map Series Map No. 2 (1:750,000 scale).

Kleinfelder (2023a). “Seismic Evaluation Technical Approach Memorandum, ULDC & FEMA Levee Certification Project, Sacramento Area Flood Control Agency Levee Systems, Sacramento and Sutter Counties, California,” dated September 29, 2023.

Kleinfelder (2023b). “Seismic Evaluation Ground Motion Parameter Selection Memorandum, ULDC & FEMA Levee Certification Project, Sacramento Area Flood Control Agency Levee Systems, Sacramento and Sutter Counties, California,” dated October 13, 2023. 24001006.001A/SAC25R179413 Page 31 of 32 April 16, 2025 © 2025 Kleinfelder
Unruh, J., and Humphrey, J., 2017, Seismogenic Deformation Between the Sierran Microplate and Oregon Coast Block, California, USA. The Geological Society of America v. 45, no. 5, pp. 415-418.

Unruh, J., Humphrey, J., and Barron, A., 2003, Transtensional Model for the Sierra Nevada Frontal Fault System, Eastern California. Geology v. 31, no. 3, pp. 327 – 330.

URS Greiner (2000). “Plans for American River Watershed Project (Common Features), California Left (South) Bank Levee Straightening, Contract 2,” dated January 18, 2000.

URS (2011). “Supplemental Geotechnical Data Report (SGDR), American River Study Area, Urban Levee Geotechnical Evaluations Program, Contract 4600007418,” dated June 2010 (Issue date: 06- 2010).

URS (2015a). “ULE Geotechnical Evaluation Report, American River Study Area, Urban Levee Evaluations Project, Contract 4600008101,” dated January 2015 (Issue date: 02-16-2015).

URS (2015b). “ULE Geotechnical Evaluation Report Volume 2, Remedial Alternatives, Sacramento River Study Area, Urban Levee Evaluations Project, Contract 4600008101,” dated January 2015 (Issue date: 02-04-2015).

URS (2015c). “ULE Geotechnical Evaluation Report Volume 2, Remedial Alternatives, South Sacramento Streams Study Area, Urban Levee Evaluations Project, Contract 4600008101,” dated April 2015 (Issue date: 04-21-2015)
URS (2015d). “Guidance Document for Geotechnical Analyses, Urban Levee Geotechnical Evaluations Program, Contract 4600008101,” dated April 2015.

United States Army Corps of Engineers (USACE) (1990). “Settlement Analysis, EM 1110-1-1904,” dated 30 September 1990.

USACE (2001). “Geotechnical Investigations, EM 1110-1-1804”, dated 1 January 2001.

USACE (2015). “Geotechnical Office Report, American River Watershed Common Features Project General Reevaluation Report,” dated October 2013.

USACE (2016). ER 1110-2-1806 Earthquake Design and Evaluation for Civil Works Projects.

Wagner, D.L., Jennings, C.W., Bedrossian, T.L., and Bortugno, E.J. (1981). Geologic Map of the Sacramento Quadrangle, California, 1:250,000 scale, California Department of Conservation, Geological Survey, Regional Geologic Map Series, Map No. 1A. 24001006.001A/SAC25R179413 Page 32 of 32 April 16, 2025 © 2025 Kleinfelder
Zhao et al. (2006). Attenuation Relations of Strong Ground Motion in Japan using Site Classification Based on Predominant Period. Bulletin of the Seismological Society of America, V. 96, No. 3, pp. 898-913.
24001006.001A/SAC25R179413 April 16, 2025
© 2025 Kleinfelder

FIGURES
____________________________________________________________________________ ¨¦§5
¨¦§80
¨¦§80
¨¦§5
¨¦§80
¨¦§80
£¤50
£¤50
ÃÆ

CALIFORNIA
160
ÃÆ
CALIFORNIA ÃÆ 16

CALIFORNIA
99 ÃÆ

CALIFORNIA
16 ÃÆ

CALIFORNIA
16 !(
!(
!(
!(
!(
!(
BLNL-5
BLNL-4
BLNL-2
SREL-1
BLNL-1
BLNL-3
SREL-5
SREL-4
SREL-9
SREL-6
ARSL-4
ARSL-5
ARSL-2
SREL-10
SREL-2
SREL-3
ARSL-1
SREL-7
ARSL-3
ARSL-6
SREL-8
1425+00
1178+00
1770+00
1635+49
1019+00
1707+50
1245+00 1431+25
1335+86
1286+00
1086+00
1135+00
1117+55
1381+93
1671+00
1195+00
1214+00
987+18
993+18
1136+74
1034+10
1004+40
Confluence
American
River East
Pocket
SREL South
Little Pocket
Arcade Creek
NTMN-5
NTMN-4
1000+00

SITE MAP
PROJECT:

FILE NAME:

FIGURE
1-1
DRAWN:

CHECKED BY:

DRAWN BY:
24001006.001A
NOV 2024
A.LEONARD
SACRAMENTO, CA FILE: \\azrgisstorp03\GIS_Projects\Client\SAFCA\24001006.001A-SeismicPerformanceSumReport\PRO\SAFECA_working\SAFECA_working.aprx ALeonard 12/2/2024 0 2 4
Kilometers
Locations are Approximate £

AMERICAN RIVER SOUTH LEVEE SYSTEM

SEISMIC PERFORMANCE SUMMARY REPORT

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SAFCA LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
Service Layer Credits: World Imagery: Earthstar Geographics; ESRI World Imagery, Maxar Vivid Advanded image dates
4/12/2022, 4/26/2022, and 5/4/2022; SACOG Orthos image
date 3/18/2022.

F1-1_ARSLS_SiteMap
Explanation
!( Analysis Control Point
ARSL-4 Seismic Segment
R.HOCHSTATTER
American River
Sacramento
River
ARSL - American River South Levee
SREL - Sacramento River East Levee
BLNL - Beach Lake North Levee
FIGURE
DRAWN BY:

PROJECT NO.

CHECKED BY:

REVISED:

DATE:

SEISMIC PERFORMANCE SUMMARY REPORT
AMERICAN RIVER SOUTH LEVEE SYSTEM 1-3 ULDC & FEMA LEVEE CERTIFICATION PROJECT

SAFCA LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA

SEISMIC EVALUATION WORKFLOW
CHART 24001006 MRZZ 10/23/2023 Phase 1: Screening Review of Existing Analysis Yes No Yes No No Yes Yes No NO FURTHER

ANALYSIS

NO FURTHER

ANALYSIS
Yes No Critical Section for
Reach Seismic
Performance? Phase 2: Targeted Evaluation
Original Analysis Or
Conditions Indicate
Susceptible to
Deformation*?
Original Analysis
Adequate? Original PGA
>
New PGA
Flow Failure
(FOS<1) with
Original PGA? Yes No
Preliminary Work Flow Failure
(FOS<1)?
Coordinate on
Impacts
No Yes NO FURTHER
ANALYSIS Revise Reach
Limits if Needed
Report
Deformation &
Results

TARGETED

EVALUATION

REQUIRED

NO FURTHER
ANALYSIS Not Used Finalize SPSR Prepare PERP Meets ULDC Seismic Criteria
*Deformation includes potential for liquefaction
induced settlement, lateral spread, seismic
induced slope displacement, and related.

REGIONAL GEOLOGY
PROJECT:

FILE NAME:

FIGURE
2-1
DRAWN:

CHECKED BY:

DRAWN BY:
24001006.001A
NOV 2024
R.HOCHSTATTER
A.LEONARD
F2-1_ARSLS_Geology
Explanation
Levee Alignment
SACRAMENTO, CA FILE: \\azrgisstorp03\GIS_Projects\Client\SAFCA\24001006.001A-SeismicPerformanceSumReport\PRO\SAFECA_working\SAFECA_working.aprx ALeonard 11/22/2024 0 2 4
Kilometers
Wagner, D.L., C.W. Jennings, T.L. Bedrossian, and
E.J. Bortugno, 1981, Geologic Map of the
Sacramento Quadrangle, California, 1:250,000,
California Division of Mines and Geology Regional
Geologic Map Series, Map No. 1A.

Locations are Approximate
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Basin deposits
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American River South Bank
Sacramento River East Levee
Beach Lake North Levee

AMERICAN RIVER SOUTH LEVEE SYSTEM

SEISMIC PERFORMANCE SUMMARY REPORT

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SAFCA LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
2-2
24001006.001A
MAR 2025
K. HAGAN
R. HOCHSTATTER
F2-2_ARSL_Geology.pagx
The information included on this graphic representation has been compiled from a variety of sources and is subject to change without notice. Kleinfelder makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness, or rights to the use of such information. This document is not intended for use as a land survey product nor is it designed or intended as a construction design document. The use or misuse of the information contained on this graphic representation is at the sole risk of the party using or misusing the information.

PROJECT:

CREATED:

CREATED BY:

CHECKED BY:

FILE NAME:

FIGURE
Date: 3/13/2025 User: KHagan Path: \\azrgisstorp03\GIS_Projects\Client\SAFCA\24001006.001A-SeismicPerformanceSumReport\PRO\SAFECA_working\SAFECA_working.aprx

AMERICAN RIVER SOUTH LEVEE

GEOLOGY MAP

AMERICAN RIVER SOUTH LEVEE SYSTEM

SEISMIC PERFORMANCE SUMMARY REPORT

SAFCA LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
SACRAMENTO, CA \\azrgisstorp03\GIS_Projects\Client\SAFCA\20222866.003A-C4NBLL_APP\Vicinity_GDR.pagx PLOTTED: 3/13/2025, KHagan

SACRAMENTO RIVER EAST LEVEE

GEOLOGY MAP

AMERICAN RIVER SOUTH LEVEE SYSTEM

SEISMIC PERFORMANCE SUMMARY REPORT

SAFCA LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
FIGURE
2-3
F2-3_ARSLS_Geology.pagx
FILE NAME:

CHECKED: R.HOCHSTATTER
DRAWN BY: K. HAGAN
DRAWN: MAR 2025
PROJECT: 24001006.001A The information included on this graphic representation has been compiled from a
variety of sources and is subject to change
without notice. Kleinfelder makes no
representations or warranties, express or
implied, as to accuracy, completeness,
timeliness, or rights to the use of such
information. This document is not intended
for use as a land survey product nor is it
designed or intended as a construction
design document. The use or misuse of the
information contained on this graphic
representation is at the sole risk of the party
using or misusing the information.
2-4
24001006.001A
MAR 2025
K. HAGAN
R. HOCHSTATTER
F2-4_BLNL_Geology.pagx
The information included on this graphic representation has been compiled from a variety of sources and is subject to change without notice. Kleinfelder makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness, or rights to the use of such information. This document is not intended for use as a land survey product nor is it designed or intended as a construction design document. The use or misuse of the information contained on this graphic representation is at the sole risk of the party using or misusing the information.

PROJECT:

CREATED:

CREATED BY:

CHECKED BY:

FILE NAME:

FIGURE
Date: 3/13/2025 User: KHagan Path: \\azrgisstorp03\GIS_Projects\Client\SAFCA\24001006.001A-SeismicPerformanceSumReport\PRO\SAFECA_working\SAFECA_working.aprx

BEACH LAKE NORTH LEVEE

GEOLOGY MAP

AMERICAN RIVER SOUTH LEVEE SYSTEM

SEISMIC PERFORMANCE SUMMARY REPORT

SAFCA LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
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SREL-6
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ARSL-2
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SREL-3
ARSL-1
SREL-7
ARSL-3
ARSL-6
SREL-8
American
River
Sacramento
Riv
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SEISMIC VULNERABILITY

CLASSIFICATIONS FOR

NATOMAS BASIN LEVEES
PROJECT:

FILE NAME:

FIGURE
6-1
DRAWN:

CHECKED BY:

AMERICAN RIVER SOUTH LEVEE SYSTEM

SEISMIC PERFORMANCE SUMMARY REPORT

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SAFCA LEVEE SYSTEMS
F6-1_ARSLS_SeisVuln SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA R.HOCHSTATTER
The information included on this graphic representation has been compiled from a variety of sources and is subject to change without notice. Kleinfelder makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness, or rights to the use of such information. This document is not intended for use as a land survey product nor is it designed or intended as a construction design document. The use or misuse of the information contained on this graphic representation is at the sole risk of the party using or misusing the information. 0 2 4
Kilometers
Locations are Approximate £
Service Layer Credits: World Imagery: Earthstar Geographics; ESRI World Imagery, Maxar Vivid Advanded image dates
4/12/2022, 4/26/2022, and 5/4/2022; SACOG Orthos image
date 3/18/2022.

ARSL-4 Seismic Segment
ARSL - American River South Levee
SREL - Sacramento River East Levee
BLNL - Beach Lake North Levee
Explanation
Low Vulnerability
Medium Vulnerability
High Vulnerability
24001006.001A/SAC25R179413 April 16, 2025
© 2025 Kleinfelder

APPENDIX A

SEISMIC TECHNICAL APPROACH MEMORANDUM
_____________________________________________________________________ 24001006.001A/SAC23M158525_R2 Page 1 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701

GROUND MOTION PARAMETER SELECTION MEMORANDUM
DATE: February 9, 2024
TO: Mr. Pete Ghelfi, PE
Director of Engineering
Sacramento Area Flood Control Agency
1325 J Street, Suite 1700
Sacramento, CA 95814
FROM: Ryan Hochstatter, EIT
Zia Zafir, PhD, PE, GE
SUBJECT: Revised Seismic Evaluation Ground Motion Parameter Selection Memorandum ULDC & FEMA Levee Certification Project
Sacramento Area Flood Control Agency Levee Systems
Sacramento and Sutter Counties, California
____________________________________________________________________________

INTRODUCTION
This technical memorandum presents the regional ground motion hazard analysis (GMHA) approach and inputs, including the development of peak horizontal acceleration (PHA) and design response spectral values to support the seismic vulnerability evaluation of levees located in the Sacramento Area of California consistent with the requirements of the Urban Levee Design Criteria (DWR, 2012).

This memorandum has been prepared consistent with the requirements of the approved scope of work for the subject project outlined in our proposal dated May 5, 2023, as well the GMHA methodology described in our Seismic Evaluation Technical Approach Memorandum dated September 5th, 2023.

PURPOSE
Sacramento Area Flood Control Agency (SAFCA) is working with a team of consultants to obtain ULDC and Federal Emergency Management Agency (FEMA) certifications for the Sacramento area levees. The purpose of this document is to provide ground motions in terms of peak horizontal acceleration (PHA) based on the new seismic sources and ground motion models. Development of ground motions follow the methodology presented in our Technical Approach Memorandum dated September 5, 2023.

The levees will be organized by selection of “sections” instead of reaches due to the variable nature of subsurface conditions under levees. Sections may overlap multiple reaches or reaches may be subdivided into multiple sections. Note that for sections encompassing or divided by roadway overcrossings, the overcrossings will be simplified to their centerlines, and additional improvements to the levee for overcrossing abutments will be neglected. 24001006.001A/SAC23M158525_R2 Page 2 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701

PROJECT FEATURES
Figure 1 shows the following levee systems and their associated component levees. The levee systems are summarized in Table 1 below.

Table 1
Levee Systems and Component Levees
Levee System Reach
1 - Dry Creek Dry Creek North Levee
2 - Robla-Arcade
Dry Creek South / Robla Levee
Natomas East Main Drainage Canal (NEMDC) East Levee - Robla to Arcade Creek Arcade Creek North Levee
3 - American
North
Arcade Creek South Levee
NEMDC East Levee - Arcade Creek to American River
American River North Levee
4 - American
South
American River South Levee
Sacramento River East Levee (SREL) -American River to NBLL North Beach Lake Levee
5 - Natomas
Basin
Natomas Cross Canal South Levee (NCC)
SREL - NCC to Powerline Road
SREL - Powerline Road to American River
American River North Levee - Sacramento River to NEMDC
NEMDC West Levee
Pleasant Grove Creek Canal (PGCC) West Levee

GOVERNING STANDARDS
Methodology for conducting seismic vulnerability evaluation of levees is governed by design criteria developed by the California Department of Water Resources (DWR). Relevant publications that will be the primary source for Kleinfelder’s analysis includes:
• Urban Levee Design Criteria (ULDC, 2012) “Section 7.7 – Seismic Vulnerability” • Urban Levee Evaluations Project Guidance Document for Geotechnical Analysis (ULE, 2015), DWR and URS, “Section 6.0 – Seismic Analysis”
Additionally, ground motion parameter development for evaluations is governed by applicable US Army Corps of Engineer’s Regulations and Manuals (ER & EM). Design guidance applicable to the seismic evaluation includes:
• Engineering Manual (EM) 1110-2-1913 (April 2000, USACE) “Design and Construction of Levees” • Engineer Regulation (ER) 1110-2-1806 (May 2016, USACE) “Earthquake Design and Evaluation for Civil Works Projects”
24001006.001A/SAC23M158525_R2 Page 3 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 • Engineering and Design Technical Letter (ETL) 1110-2-580 (March 2013, USACE) “Guidelines for Seismic Evaluation of Levees”

SEISMIC SOURCE INPUTS
General
Site characterization was completed in general accordance with ER 1110-2-1806 §8. In general, this includes characterization of the topographic, hydrologic, and geologic/stratigraphic characteristics of the site and the associated engineering properties as needed for seismic evaluations.

Regional Setting
The regional setting is used in developing seismic source models and informs the interpretation of local geology. The regional setting includes discussion of the regional geology and stratigraphy, seismotectonic setting, faulting and fault rupture, and historic seismicity. Details are discussed below.

Regional Geologic Setting
The study area is located within the southern portion of the Sacramento Valley, within the Great Valley geomorphic province. The Great Valley province is a north-south trending 400-mile by 50-mile long alluvial plain in central California comprised of the Sacramento Valley in the north and the San Joaquin Valley in the south. The Sacramento Valley contains thousands of feet of accumulated fluvial, overbank, and alluvial fan deposits derived from erosion of the adjacent Sierra Nevada mountains to the east, northern Coast Range mountains to the west, and Klamath and Cascade mountains to the north. These deposits are primarily comprised of Quaternary and Tertiary age (present day to 56 million years ago) alluvial deposits and include clays, silts, sands, and gravels. The alluvial deposits thin out at the margins of the Great Valley Province, exposing underlying bedrock units. The Foothills Metamorphic Belt and the basement complex of the Sierra Nevada Batholith to the east are exposed along the eastern boundary of the valley. Sedimentary and mélange bedrock of the northern Coast Range mountains are exposed to the west. Meta-sedimentary, mélange, igneous, and volcanic bedrock of the Klamath and Cascade mountains are exposed to the north.

The study area has been regionally mapped by a number of geologists. These include published maps by Wagner et al. (1981), Helley and Harwood (1985), Gutierrez, C.I. (2011), and Fugro William Lettis & Associates (FWLA, 2010). Wagner et al. (1981) provides the most regional context but very little detail relative to the project area. Helley and Harwood mapping (performed at a scale of 1:62,500) focuses on Quaternary geologic units based on geomorphology. Gutierrez, C.I. (2011) is the most recent map of the study area and provides more current regional geologic mapping relative to Helley and Harwood (1985).

Fugro William Lettis & Associates (FWLA, 2010) provides more detailed surficial Quaternary deposits.

The project area is shown on Wagner D. L. (1981) on Figure 1.

Subsurface Stratigraphy at Depth
The Great Valley geomorphic province is characterized as an elongated low-lying basin through central California filled with thousands of feet of sediment. The Great Valley province is situated on the remnants of the Jurassic age forearc basin of the Pacific Plate subducting under the North American Plate. The forearc basin is a regional and asymmetrical feature with the western portion being deepest 24001006.001A/SAC23M158525_R2 Page 4 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 (Harwood and Helley, 1987). The sediment within the basin is referred to collectively as the Great Valley Sequence, comprised of present day to Eocene age alluvial deposits. Underlying the Great Valley Sequence are Cretaceous age marine sedimentary rocks such as shales and sandstones. Underlying the marine sedimentary rocks is an ophiolite suite which is typically comprised of ultramafic (i.e. periodite and dunite) to mafic rocks (i.e. gabbro and basalt) overlain by shale and chert (Harden 1998).

Seismotectonic Setting
The site is located in the Western United States (WUS) in the transform plate boundary region between the Pacific Plate (transitioning northwest) and the North American Plate (see Figure 4). The site lies within the Sierra Nevada-Great Valley block (a.k.a., the Sierra Nevada microplate, or SNGV) which generally is thought to act as an independent block that has ‘tilted’ westward. The SNGV block is bounded on its eastern edge by a zone of faults known as the Walker Lane Belt, beyond which is the crustal extensional region of the Northern Basin and Range. Further afield in the northwestern portion of the state and extending northward to the pacific northwest, the Juan de Fuca plate is currently subducting below the North American plate in a region known as the Cascadia Subduction Zone (Humphreys and Coblentz, 2007; Unruh and Humphrey, 2003, 2017).

Regional stress build-up due to the northwestern movement of the Pacific Plate is primarily released through displacement along faults within the San Andreas fault system (e.g. San Andreas fault, Hayward fault, etc.) and to a lesser extent by displacements along faults within the Walker Lane Belt. Crustal extension of the Northern Basin and Range has led to the development of stress in the east-west direction and caused development of an extensive system of faults within the Northern Basin and Range (Fey and Humphreys, 2008; Field et al., 2013).

Faults and Fault Rupture
Regional faulting and potential for fault rupture directly impact the potential sources of seismicity and thus the seismic risk at a site. For this study, Quaternary age faults (considered potentially seismically active) were reviewed consistent with the recommendations of EM 1110-2-1806. Based on our review, a number of Quaternary and older faults were identified as shown on Figure 3, with select Quaternary faults within 100 km1of the site listed in Table 2. Detailed discussion of faulting and potential for fault rupture is provided below.

The closest potentially active system to the site is the Great Valley fault system which lies to the west of the site. The closest segments of the Great Valley system include the Midland fault2located roughly 30 km to the southwest of the site (DWR, 2007; Unruh and Hitchcock, 2009), and the Dunnigan Hills3thrust fault which lies to the west-northwest (Jennings and Bryant, 2010; Parrish, 2018). Other significant active faults to the west of the site include faults within the San Andreas system (San Andreas fault, Hayward fault, Calaveras fault, etc.). East of the site, the active fault systems include the Foothills fault system (Paynes Peak fault, Spenceville fault, Maidu East fault, etc.) and a series of strike-slip and normal 1 A 100 km distance was used in the table for consistency with the distance to which more detailed seismic source characterization was completed, see Section 3.3 for details.
2 The Midland fault zones northern extension consists of somewhat complex geometry in the vicinity of Rio Vista and northward. Detailed geometry not shown in this report, see Unruh and Hitchcock (2009) for details. 3 The Dunnigan Hills (aka. Zamora Fault) is mapped by some researchers along the northeastern edge of the Dunnigan Hills (Harwood and Helley, 1987; USGS and CGS, 2006). However, the active fault has more recently been mapped to the southwest by Parrish (2018) and others and is considered more appropriate for evaluation of active and potentially active portion of the fault in this study. 24001006.001A/SAC23M158525_R2 Page 5 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 faults in and around the Tahoe region, as well as faults associated with crustal extension of the Northwestern Basin and Range. Much further afield, the Cascadia subduction zone (northwest corner of the state) can generate very large magnitude events and may have the potential to impact long-period ground motions at the site.

There are a series of older faults and folds that underlie the central part of the Great Valley and include the possible southeastern extension of the Willows fault and the Stockton fault. The Willows and Stockton faults are generally accepted to be seismically inactive, with deformation along the southern end of the Willows fault (closest fault to the site) considered to be older than about 3.4 million years (Harwood and Helley, 1987). Along the western edge of the Sacramento Valley, the Thornton Arch4as well as the East and West Valley faults are, likewise, considered seismically inactive with the most recent activity generally considered pre-quaternary in age (Jennings and Bryant, 2010; Parrish, 2018). These inactive faults are not considered to be significant to hazard potential at the site and thus are not listed in Table 2 although they are shown on Figure 3 for completeness.

Table 2
Potentially Active or Active Quaternary Age or Younger Faults Within 125 Km of Site Name Name Name
Alexander fault Greenville fault Poorman Gulch fault
Antioch fault Haupt Creek fault Pope Creek fault
Ashland fault Hayward fault Putah Creek
Bad Ridge fault Highway 49 fault Putah Creek fault
Bartlett Springs fault zone Hunting Creek fault Red Road fault Bennett Valley fault Hunting fault Redwood Hill fault
Black Butte fault Ione fault Rescue fault
Bowie Flat fault Kennedy fault Resort fault
Burdell Mountain fault Kirby Hills fault Rio Vista fault Calaveras fault Konocti Bay fault Rodgers Creek fault
Carnegie fault Lagoon Valley fault San Joaquin fault
Chabot fault Lakeview fault Sherburne Hills thrust fault Chico Monocline fault Little Indian Valley fault Soda Creek fault Clayton fault Livermore fault Southampton fault
Cleveland Hill fault Los Positas fault Spenceville fault Clover Valley fault Maacama fault Swain Ravine fault
Cobb Mountain fault Maidu East fault Tolay fault
Concord fault Marsh Creek fault unnamed
Cordelia fault Maxwell Creek fault Vaca fault
Corning fault Midland fault Vernalis fault
Corral Hollow fault Midway fault Verona fault
Cross Spring fault Mill Valley fault Waters Peak fault
Deadman fault Miller Creek fault West Napa fault
4 Previous studies by the California Department of Water Resources (DWR, 2007) have considered possible activity (probability of activity of 20 percent) along the Thornton Arch. However, Jennings and Bryant (2010) and other more recent studies by the various researchers have not considered this feature to be potentially active.
24001006.001A/SAC23M158525_R2 Page 6 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 Name Name Name
Dewitt fault Mocho fault Wildcat fault
Dunnigan Hills fault Moraga fault Williams fault
Franklin fault Northern Calaveras fault Wilson fault
Giant Gap fault Paynes Peak fault Youngs Creek fault
Green Springs Run fault Pinole fault
Green Valley fault Pleasanton fault
Notes:

Refer to Figure 3 for relative fault distances from project.

Historic Seismicity
One of the major factors for evaluation of seismic hazard is the historic record of seismicity. Patterns of historic seismicity can be used to identify known or inferred impacts of historical seismicity on a project.

Catalogs of historic seismicity are also used to characterize seismic sources in models such as those developed by Field et al. (2013) and others. This section discusses regional historic seismicity.

Kleinfelder compiled and reviewed data from the USGS ANSS Comprehensive Earthquake Catalog, known as ComCat, which contains historical seismic data compiled by the USGS from multiple sources. A search radius of 300 km centered on the site was used and yielded a record covering the years from 1808 to 2019.

Based on review of this data, the closest seismic events to the site are a set of minor events (Mw < 4) that occurred in 2002 located about 15 to 16 km northwest of the site. Another minor event occurred in 2003 located about 16 km to the southeast of the site. These events constitute the only recorded seismicity in the near-field vicinity (e.g. within about 15km) of the site and are small enough not to be of engineering significance.

More significant historic seismicity has been observed along some of the nearby active faults (see Figure 3). Historical seismicity along the Great Valley thrust fault system includes a cluster of low magnitude events near the south end of the Dunnigan Hills section. Other events along the Great Valley system include the 1892 (~Mw6.6) Vacaville-Winters sequence near the Gordon Valley section and the 1892 (Mw5.5) event near the Midland Fault (Unruh and Moores, 1992; USGS, 2019). The foothills fault system has also historically been active, with a large number of earthquakes observed near Oroville Dam (possibly reservoir induced seismicity) and significant micro-seismicity reported between Oroville and Folsom reservoirs, particularly near the Rocklin-Penryn pluton (e.g. Cramer et al, 1978).

Far-field events include a number of significant large earthquakes including the 1868 (Mw7.0) Hayward earthquake, the 1906 (Mw7.8) “Great” San Francisco earthquake, the 2014 (Mw6.0) South Napa earthquake, the 1838 (Mw7.4) San Francisco Peninsula earthquake, the 1865 (Mw6.5) Santa Cruz Mountains earthquake, and the 1989 (Mw6.9) Loma Prieta earthquake. These events are located on faults within the San Andreas fault system (Hayward, San Andreas, etc.). Review of the historic records indicates only minor impacts or damage from these events in the Sacramento region.

Intensity values such as Modified Mercalli Intensity (MMI) tend to provide an indication of the effect of historic seismicity on people and buildings and are useful in measuring the significance of events at a site. MMI values in this study were estimated using the relationship of Atkinson et al. (2014). The majority of the historic earthquake event data used in the evaluation was obtained from the USGS 24001006.001A/SAC23M158525_R2 Page 7 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 National Seismic Hazard Map project de-clustered earthquake catalog (e.g. Petersen et al. 2014). A table of historically significant seismic events, based on MMI, is provided below in Table 3. The most significant events impacting the site from this evaluation are highlighted in bold. These include the 1892 Vacaville-Winters sequence (e.g. Great Valley fault system) and the 1906 “Great” San Francisco earthquake (e.g. San Andreas fault system).

The estimated MMI values were checked against historic data for select events. For a recent event, the MMI reported by the USGS from observations for the South Napa event was 3.5 and is consistent with the estimated MMI. Some older events have reported MMI values as high as VI to VII based on record review by the California Geological Survey (CGS, Historic Earthquake Online Database, accessed 2020).

However, it is likely that these higher MMI values are influenced by lower quality of construction generally prevalent at the time.

Table 3
Select and Significant Historic Earthquakes and
Estimated Historical Impact Potential Using MMI
Magnitude
(Mw)
Event Date Event Name/Location4
Estimated
MMI1,2

7.4 6/1/1838 San Francisco Peninsula IV

7.3 1/1/1852 Pyramid Lake IV

7.9 1/9/1857 Great Fort Tejon IV

7.0 10/21/1868 Hayward IV

6.0 5/19/1889 Near Collinsville IV

6.6 4/19/1892 Vacaville-Winters Earthquake V

6.4 3/31/1898 Mare Island IV

7.8 4/18/1906 “Great” San Francisco V

6.9 10/18/1989 Loma Prieta IV

6.0 8/24/2014 South Napa3IV
Notes:

1. Approx. Modified Mercalli Intensity (MMI) developed using procedure of Atkinson et al. (2014).

2. MMI – IV- Light Shaking; V – Moderate Shaking; VI – Strong Shaking; VII – Very Strong Shaking; VIII – Severe Shaking; IX – Violent Shaking; X – Extreme Shaking (USGS.gov accessed 2020)

3. 2014 Napa earthquakes data from USGS earthquake hazards program (https://earthquake.usgs.gov/ earthquakes/eventpage/nc72282711/executive).

4. Some events including Santa Cruz Mountains earthquake (1865), induced seismicity sequence near Oroville, and microseismicity, etc. not listed due to low impact/magnitude.

GMHA IMPLEMENTATION
To be consistent with previous work performed by URS and DWR for the Urban Levee Evaluations (ULE) project, the probabilistic seismic hazard analysis (PSHA) approach was selected to perform the GMHA for this study and estimate the ground motion parameters (typically peak ground and spectral accelerations), with some modifications in implementation based on current standards of practice for probabilistic evaluations in California (e.g., “Grand Inversion” approach). Only the probabilistic approach is used, which is consistent with requirements of ULDC, and as permitted by ER 1110-2-1806 §7d. 24001006.001A/SAC23M158525_R2 Page 8 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 Existing Ground Motion Data
Previous development of ground motion parameters in the area was performed by URS in 2007 as part of the Delta Risk Management Strategy (DRMS), which was updated and expanded on in 2012 by URS as part of the Department of Water Resources’ (DWR) Urban Levee Evaluation (ULE) project. A 200-year return period seismic hazard map was developed for the ULE area, which encompasses the ULDC area.

The probabilistic seismic hazard analysis performed for the ULE area was based on the UCERF2 seismic source characterization. The ground motion parameters developed by URS consisted of peak horizontal acceleration for stiff soil condition where Vs30 was taken as 335 m/s (1100 ft/s), which typically occurs depths of 100 to 120 feet below the ground surface. In addition, associated earthquake magnitude was also estimated.

For this project the source characterization by others will be reviewed, where high-quality peer reviewed seismic source models are available. This will include studies performed by the United States Geological Survey applicable to the project region (e.g. Petersen et al. 2014, 2019), statewide studies performed as part of the third Uniform California Earthquake Rupture Forecast (UCERF3 - Field et al., 2013). It is expected the UCERF3 characterization will be primarily used for this project due to its wide adoption in other work and for consistency with the deprecated UCERF2 model used in previous work by URS. Additionally, Petersen et al. (2014, 2019) models will be used for far-field seismic sources outside of California (e.g. Cascadia, etc.)
Analysis performed by URS in 2012 for ULE identified several potential seismic sources in the area that were not included in the UCERF2 model (i.e. Northern Midland fault zone). The UCERF3 model will be evaluated for inclusion of these sources.

Following evaluation of existing design ground motion data, segments of levee with either non-existent or out-of-date seismic data will be analyzed according to procedures described below.

Probabilistic Seismic Hazard Analysis (PSHA)
The PSHA approach that will be used to estimate the ground motion parameters (typically peak ground and spectral ground accelerations) is generally consistent with requirements of ULDC, with some modifications in implementation based on current standards of practice for probabilistic evaluations in California (e.g. “Grand Inversion” approach). The probabilistic approach is used in place of a deterministic approach as permitted by ER 1110-2-1806 §7d.

A site-specific PSHA is a useful tool in the evaluation of the potential ground motion hazard at a site. The model generally includes a representative seismic source model (such as geometry, style of faulting, magnitude, etc.), appropriate recurrence relationships, and appropriate ground motion models (aka. attenuation relationships). Modifications to the standard approach can also incorporate site-specific evaluation of site effects such as amplification. The model can be used to quantify the potential for strong ground shaking at a site. The hazard results are typically interpreted at a given earthquake return period to provide an equal or uniform hazard spectrum (UHS) for use in design.

The PSHA uses a logic tree approach to account for epistemic uncertainty in the model, with aleatoric variability accounted for in the uncertainty associated with various models (e.g. GMM’s). The logic tree 24001006.001A/SAC23M158525_R2 Page 9 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 is developed to account for uncertainties in the source models, ground motion models, and other items impacting the results. Important source characteristics include slip rates and fault lengths, magnitude and recurrence intervals of potential seismic events, distance from the site to the causative source, and other parameters. The effects of site soil conditions, and other considerations such as basin effects, can be accounted for using ground motion models (GMMs).

The theory behind the probabilistic approach to seismic risk analysis has been developed over many years (Cornell, 1968, 1971; Merz and Cornell, 1973; SSHAC, 1997), and is based on the "total probability theorem". Generally, this work uses an assumption that earthquakes are events that are independent of time and space from one another (e.g. time independent models). According to this approach, the probability of exceedance PE(z) at a given level of ground motion, z, at the site within a specified time period, t, is related to the annual frequency of exceedance v(z) by:

𝑃𝐸
(𝑧) = 1 −𝑒𝑥𝑝 𝑒𝑥𝑝 (−𝑣(𝑧) ∗ 𝑡)
Different probabilities of exceedance may be selected, depending on the level of performance required.

The return period is essentially equivalent to the reciprocal of v(z).

The PSHA is conducted using three generalized steps that include the following.

1. Development of an appropriate seismic source model including source characterization, development of recurrence relationships, and appropriately capturing uncertainty

2. Selection of appropriate ground motion models (and site amplification models, if appropriate)

3. Conducting the calculation and processing the results The annual frequency of exceedance of a certain ground motion level can be found by summing the rates for all sources, N, with the rate for each source determined by summing over all magnitudes and source to site distances, and so forth. The annual frequency of occurrence of earthquakes of magnitude, mi, on seismic source, n, is λ(mi). The probability of an earthquake of magnitude, mi, on source, n, occurring at a certain distance, rj, from the site is P(R = rj | mi) while the probability that the ground motion level, z, will be exceeded is given as P(Z>z | mi,rj). Thus, mathematically the basic formulation for the annual frequency of exceedance, v(z), is given by (EM 1110-2-6050):
𝑣(𝑧) = ∑
𝑁
[ ∑
𝑀
𝜆(𝑚𝑖
) ∗ ∑
𝑅
𝑃(𝑚𝑖
) ∗ 𝑃(𝑚𝑖
, 𝑟𝑗)]
Modern computers make the above calculation, while computationally expensive, easily implementable at most sites. We will use the computer program HAZ (Powers, 2017) for our probabilistic analysis, which implements the above general equation. Uncertainties are accounted for within the source model using a logic tree approach and using multiple models, where appropriate. We note that HAZ does not currently provide the uncertainty bands (16th and 84th percentiles) and thus uncertainty bands will not be evaluated or presented.
24001006.001A/SAC23M158525_R2 Page 10 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 Seismic Source Model
The seismic source model for a site contains all information required to characterize potential seismic sources for use in evaluation of ground motion parameters. The source model typically includes information on the geometry (e.g. length, dip, depth, etc.), style of faulting, magnitude, and recurrence relationships for all potentially active seismic sources within a distance capable of significantly impacting a site. The source model used for this work is discussed below.

Detailed review of select nearby seismic sources was performed and included review of the Midland fault, Dunnigan Hills fault, Foothills fault system, and other nearby faults. Other faults are not discussed in detail, but discussion is available in the referenced literature:
• Midland fault - The Midland fault was not considered active by Petersen et al. (2008). However, DWR (2007) and follow on work by Unruh and Hitchcock (2009) conclusively showed ongoing activity along the Midland fault within the Sacramento-San Joaquin delta. The Midland fault was characterized by DWR (2007) using a source zone to represent the northern portion of the Midland fault zone, while other later studies (Merriam, 2012; Petersen et al. 2019, etc.) generally considered this source adequately characterized using a linear fault source, and that approach was considered appropriate for this study.
• Dunnigan Hills fault - Consideration of an alternative placement of the Dunnigan Hills fault (east of the Dunnigan Hills), as was done by Merriam (2012), was not considered justified based on available geologic data.
• Thornton Arch - The Thornton arch zone, a potential seismic source identified by DWR (2007), was not modeled as an independent source by most other studies. This study likewise does not explicitly consider this as a potentially active fault source based on the lack of significant folding of the overlying Miocene age continental rocks, leading to the conclusion that the structure is pre-Miocene (e.g. Harwood and Helley, 1987).
• Foothills system - The Foothills fault system (Swain Ravine fault, Spenceville fault, Dewitt fault, etc.) was modeled as a source zone by some studies or as a fault source in more recent work for UCERF3. The fault source approach and characterization of UCERF3 (e.g. Swain RavineSpenceville Fault) was adopted in this study. • Other minor faults: Other nearby, potentially active faults (e.g. Vernalis Fault, Rio Vista Fault, Black Butte fault, etc.) were generally not considered significant to the hazard at the site. These sources were not considered as independent seismogenic sources and were more appropriately modelled by background seismicity.

We used the above characterization to review available source models and determine if any site-specific modification to the models was required.

We reviewed source characterization and seismic models developed by others where high-quality peer reviewed models were available. Available models reviewed for this work included studies performed by the USGS applicable to the project region (e.g., Petersen et al. 2019), which generally adopted the results of the statewide study performed as part of the third Uniform California Earthquake Rupture 24001006.001A/SAC23M158525_R2 Page 11 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 Forecast (UCERF 3 - Field et al. 2013), and the regional study completed by the California Department of Water Resources (DWR) for the Delta Risk Management Strategy project (California DWR, 2007).

Based on the above characterization and review of the available models, the source model developed by the USGS and published by Petersen et al. (2014, 2019) was generally found to provide adequate characterization of seismic sources and uncertainties identified for inclusion in the model. No sitespecific modification was needed for this study, and thus, the model of Petersen et al. (2014, 2019) was adopted for this work without change.

Within the Western United States (WUS) region, significant independent seismogenic sources within about 300 kilometers (km) of the site are included in the model as fault sources. Very large magnitude sources, such as the Cascadia subduction zone, are included out to 500 km. Minor, potentially active faults are generally not considered significant to the seismic hazard at the site. These sources were not considered as independent seismogenic sources and were more appropriately modelled by background seismicity. Recurrence intervals and slip rates used to develop the fault models are available in referenced literature and are based on the values developed by the UCERF 3 working group.

The adopted model uses two alternative fault models, Fault Model (FM) 3.1 and FM 3.2, from the branch-averaged UCERF 3 solution to model on-fault seismicity in California. Off-fault seismicity, also known as background seismicity, is modeled using gridded seismic sources developed for consistency with each fault model. Outside of California (e.g., Cascadia, etc.), source characterization developed by Petersen et al. (2014, 2019) was used.

The seismic source model used for this work within 325 km of the site is presented on Figure 4. An abbreviated overview of significant fault sources included in the source model within 100 km of the site is provided in Attachment A1. The attached table presents a simplification of the model used for this study and does not show how the model relaxes the assumption of segmentation and allows for multifault ruptures, with numerous possible combinations. For additional details of the characterization of individual sources and associated alternative models (e.g., FM 3.1 vs FM 3.2), the reader can refer to the documentation prepared by Petersen et al. (2014, 2019) and the associated referenced documents and reports.
‘Grand Inversion’ and Recurrence Rates
The earthquake recurrence rates used in the source model will be adopted as developed by the UCERF3 project, as implemented by Petersen et al. (2019) using the branch-averaged solutions of the ‘grand inversion’. This is a departure from the older standard of practice documented in EM 1110-2-6053 and Draft EM 1110-2-6000, which solves for the entire system of faults within California simultaneously.

The ‘grand inversion’ scheme developed by the UCERF3 project team, the results of which will be adopted in this work, ‘solved’ the on-fault and off-fault recurrence rates at a system level using a set of defined constraints including the spatial probability density of off-fault seismicity, slip rate balancing, paleoseismic even rate matching, fault smoothness constraint, regional magnitude frequency distribution constraints, and fault section specific magnitude frequency distribution constraints. In simple terms the ‘grand inversion’ solves for three things: large on-fault (supra-seismogenic) event rates; small, near-fault (subseismogenic) event rates; and truly off-fault (unassociated) event rates. The 24001006.001A/SAC23M158525_R2 Page 12 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 supra-seismogenic ‘on-fault’ events are ultimately modeled using linear fault sources while the latter two categories (subseismogenic and off-fault) are considered ‘background seismicity’ and are modeled using spatially smoothed ‘grid’ of evenly spaced cells (a.k.a. gridded seismicity). The combined on-fault and off-fault solution set (fault system solution) used the logic tree solution framework shown in a generalized form on Figure 5. Our model implements the branch-averaged solutions.

The on-fault seismicity considers two potential alternative fault models, equally weighted, identified as fault model 3.1 (FM 3.1) and fault model 3.2 (FM 3.2). These fault models each contain a slightly different collections of fault traces that are broken into ‘segments’ for modeling purposes, with individual segments strung together during evaluation to create hundreds of thousands of potential fault-based ruptures or multi-rupture events. In our model, fault segments are modeled with the recurrence rates constrained during the ‘grand inversion’ by the UCERF2 ‘characteristic’ inversion branch (e.g. Schwartz and Coppersmith, 1984). Fault slip rates (deformations) are constrained by a combination of a ‘pure’ geologic deformation model and three other models that consider geologic and geodetic data including the average fault block model, NewKinema model, and Zeng-Shen model. The magnitude-area relationships used along with the associated slip-length models, as well as other solution constraints applied, are shown with weights on Figure 5 and are discussed in detail in Field et al. (2013) and associated publications.

Off-fault seismicity (e.g. background seismicity) recurrence rates are solved for simultaneously by the ‘grand inversion’. This off-fault background seismicity is intended to include all smaller earthquakes (Mw<~6.5) on major faults and earthquakes of all sizes that are not associated with known faults. The off-fault background seismicity considers spatial smoothing of a ‘grid’ of evenly spaced cells using the spatial probability density function (PDF) grids of off-fault seismicity from UCERF2 and UCERF3 (equally weighted), considering the regional constraints on the model including the total regional magnitudefrequency distribution (e.g. Gutenberg-Richter distribution), maximum off-fault magnitude, number of regional events per year greater than Magnitude 5, and other constraints as shown on the logic tree (see Figure 5). The branch-averaged, gridded seismicity solution for each fault model, as implemented by Petersen et al. (2019), was used in the source model for this work.

We note that the catalog used in this work was not updated in 2019, as re-evaluation of the grand inversion scheme requires a supercomputer. However, the USGS reviewed the catalog used for UCERF3 and concluded that the addition of recent historical events to the catalog is not needed at this time, as the additional historical events in the last half decade typically will not significantly change the model results, with changes generally small, localized, and often near active faults, and thus already adequately modeled (Petersen et al., 2019).

Ground Motion Model’s (GMM’s)
This study makes use of response spectral attenuation relationships, also known as ground motion models (GMMs), in evaluations at the site as required by ER 1110-2-1806.

Site-specific ground motions can be influenced by the styles of faulting, magnitudes of the earthquakes, and local soil conditions. Other effects such as near-source or basin effects can also influence the ground motions. The GMM’s used to estimate ground motion from an earthquake source need to directly or 24001006.001A/SAC23M158525_R2 Page 13 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 indirectly consider these effects. Many GMMs have been developed to estimate the variation of spectral acceleration with earthquake magnitude and distance from the site to the source of an earthquake.

We will use four of the Next Generation Attenuation (NGA) West 2 relationships including Abrahamson et al. (2014), Boore et al. (2014), Chiou and Youngs (2014), and Campbell and Bozorgnia (2014) with equal weights applied for all crustal faults (e.g. reverse, strike-slip, normal) included in the fault model.

The Idriss (2014) model has not been used as it is not valid for the VS30 used in our study and also for the larger distances used in this study (e.g. more than 150 km). The far-field subduction events (e.g. from Cascadia megathrust) were modeled using the relationships of Atkinson and Macias (2009), Abrahamson et al. (2016), and Zhao et al. (2006) with equal weights applied, except that for slab events the Atkinson and Macias (2009) relationship was excluded. Spectral acceleration values are obtained by averaging the individual hazard results. These GMM’s provide ‘mean’ (RotD50) values of ground motions associated with magnitude, distance, site soil conditions, and mechanism of faulting. The uncertainty in the predicted ground motion was taken into consideration by including a magnitude dependent standard error in the probabilistic analysis.

Deep Sediment Impact on Response
The Sacramento Basin, while not typically considered a true basin for purposes of seismic evaluation, does contain deep sediments which can impact the response of the system. The Campbell and Bozorgnia (2014) and Chiou and Youngs (2014) GMMs include the depth to rock (Z) parameter to better predict ground motion in regions with deep sedimentary structure. The Campbell and Bozorgnia (2014) model uses the depth to shear wave velocity of 2.5 km/s (Z2.5) and the Chiou and Youngs (2014) model uses the depth to shear wave velocity of 1.0 km/s (Z1.0). The Z1.0 and Z2.5 values can be estimated by various sources, as discussed in next section. For Northern California locations, only the Campbell and Bozorgnia (2014) factor is applied, to account for deep sedimentary structure which is analogous to a ‘basin effect’.

Therefore, the basin effect on the response spectrum either at depth or at ground surface can be considered using the appropriate site-specific Z1.0 and Z2.5 values. Previous work on DRMS (DWR, 2007) determined that the response of the levees as more sensitive to ground potions with a period lower than 1 second, so the longer period motions where deep basin effects would be most pronounced are likely not significant to the levees of this project.

Control Points and Site Parameters
Evaluation of seismic hazard and model development for site specific studies is usually completed at a control point considered representative of a structure or facility. For this project, multiple control points across the project area are considered for evaluation of ground motions. Nine points along levee alignment are considered adequate as active faults are generally located at distance from the site, and thus, small differences due to control point location variation should be minimal. The control points will be used in evaluation of distance terms (rx, rjb, rrup) required for the selected GMM’s.

The above GMMs also use a set of site parameters to account for site effects and basin effects. For the NGA West 2 relationships, these include the average shear wave velocity in the upper 100 feet (30 meters, e.g. VS30), the depth to a layer with a Vs value of 3,280 feet per second (1,000 meters per second, e.g. Z1.0), and the depth a layer with Vs value of 8,200 feet per second (2.5 km/s, e.g. Z2.5). 24001006.001A/SAC23M158525_R2 Page 14 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 The VS30 values were evaluated at depth based on data from previous reports and mapped values. for consistency with DMRS (DWR, 2007), ground motions were evaluated as a stiff soil condition where VS30 is taken as 335 m/s. it is understood that this condition typically occurs at a depth of about 100 to 120 feet below ground surface. Z1.0 and Z2.5 were developed considering various geologic factors and estimates from the NGA West 2 correlations to develop best estimate values.

The Z1.0 and Z2.5 parameters are intended to capture the basin effects on ground motion response at a given site. The Z1.0 and Z2.5 values were estimated utilizing the correlations developed for the NGA West 2 project, with justification per Petersen et al. 2019. The Z1.0 and Z2.5 values are estimated to be about

0.428 km and 1.55 km, respectively. We propose to use these values as inputs for the GMHA.

In summary, our recommended values of VS30, Z1.0, and Z2.5 are presented in Table 4 below. Further details about the development of the site parameters are presented in Attachment A2.

Table 4
Site Parameters
Point ID Latitude Longitude VS30
(m/s)
Z1.0
(km)
Z2.5
(km)
Natomas NE 38.8262 -121.5317
335 0.428 1.55
Natomas NW 38.7810 -121.6025
Natomas West 38.6904 -121.6325
Arcade Creek 38.6668 -121.4762
Confluence 38.5982 -121.5087
American River East 38.5921 -121.3344
Little Pocket 38.5293 -121.5288
Pocket 38.4989 -121.5578
SREL South 38.4447 -121.5002
Peak Horizontal Accelerations
The probabilistic geometric mean peak horizontal acceleration is taken as the geometric mean peak horizontal acceleration with a 200-year return period. The associated controlling earthquake magnitudes and distances are based on the results of the deaggregation analysis. These values are presented in Table 5. We have also provided PHA values from the previous studies for comparison in this table. It should be noted that earthquake magnitude 6.5 was used in the previous studies for the entire study area.
24001006.001A/SAC23M158525_R2 Page 15 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 Table 5
Probabilistic Peak Horizontal Acceleration and Controlling Earthquake Point ID
PHA (g) Deaggregation Results
(KLF, 2023) (DWR,
2015)
MW Distance (km)
Natomas NE 0.13 0.133 6.8 73
Natomas NW 0.14 0.144 6.8 65
Natomas West 0.15 0.160 6.7 58
Arcade Creek 0.13 0.139 6.8 72
Confluence 0.14 0.146 6.8 67
American River East 0.12 0.126 6.8 81
Little Pocket 0.14 0.152 6.7 63
Pocket 0.15 0.163 6.7 60
SREL South 0.15 0.148 6.7 62

CLOSING
This technical memorandum is for review by the subject project’s peer review panel for concurrence with the approach for the forthcoming Seismic Performance Summary Reports. This document is intended to be used as an appendix to the primary Seismic Performance Summary Report and is subject to the same limitations as in that report. If you have questions regarding this memorandum or if we may be of further assistance, please contact the undersigned.

Sincerely,
KLEINFELDER, INC.

Ryan Hochstatter, EIT Zia Zafir, PE, GE
Staff Geotechnical Engineer Sr. Principal Geotechnical Engineer

ATTACHMENTS
Figure 1 – Study Area
Figure 2 – Geologic Map
Figure 3 – Regional Faulting and Seismicity
Figure 4 – Seismic Source Model
Figure 5 – UCERF 3 Source Model Logic Tree
Attachment A1 – Significant Faults Included in Source Model Attachment A2 – Calculation Package – Shear Wave Velocity and Site Parameters 24001006.001A/SAC23M158525_R2 Page 16 of 18 February 9, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701

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Pocket
Natomas NW
SREL South
Confluence
Natomas NE
Arcade Creek
Natomas West
Little Pocket
American River East

STUDY AREA
PROJECT:

FILE NAME:

FIGURE
1 DRAWN:

CHECKED BY:

DRAWN BY:
24001006.001A
SEP 2023
M. RYAN
K. HAGAN
F1_SiteMap.mxd
Explanation
!( Analysis Control Point
Levee Alignment
SACRAMENTO, CA FILE: \\azrgisstorp03\GIS_Projects\Client\SAFCA\24001006.001A-ULDC_groundmotion\F1_SiteMap.mxd KHagan 9/21/2023 0 3 6
Kilometers
Locations are Approximate
£

SEISMIC EVALUATION GROUND MOTION

PARAMETER MEMORANDUM

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SACRAMENTO AREA FLOOD CONTROL AGENCY

LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
Service Layer Credits: Source: Esri, Maxar, Earthstar
Geographics, and the GIS User Community; ESRI World
Imagery, Maxar Vivid Advanded image dates 4/12/2022,
4/26/2022, and 5/4/2022; SACOG Orthos image date
3/18/2022.

REGIONAL GEOLOGIC MAP
PROJECT:

FILE NAME:

FIGURE
2 DRAWN:

CHECKED BY:

DRAWN BY:
24001006.001A
SEP 2023
M. RYAN
K. HAGAN
F2_Geology.mxd
Explanation
Levee Alignment
SACRAMENTO, CA FILE: \\azrgisstorp03\GIS_Projects\Client\SAFCA\24001006.001A-ULDC_groundmotion\F2_Geology.mxd KHagan 9/21/2023 0 3 6
Kilometers
Wagner, D.L., C.W. Jennings, T.L. Bedrossian, and
E.J. Bortugno, 1981, Geologic Map of the
Sacramento Quadrangle, California, 1:250,000,
California Division of Mines and Geology Regional
Geologic Map Series, Map No. 1A.

Locations are Approximate
£

SEISMIC EVALUATION GROUND MOTION

PARAMETER MEMORANDUM

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SACRAMENTO AREA FLOOD CONTROL AGENCY

LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
#
# ##
#
##
#
#
#
# #
%
%
%
%
%
! ! ! ! !
! ! ! ! !
! ! ! ! !
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@ @ @ @
@ @ @ @
@ @ @
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Qmr
Qr
Qb
Qa
Qm Modesto Formation
Riverbank Formation
Modesto-Riverbank Formations
Basin deposits
Levee and channel deposits
Historic displacement (< 150 years)
Mapped Fault Location
Dashed were Approximated
! ! ! ! Concealed
Holocene displacement (< 15,000 years)
Mapped Fault Location
Dashed were Approximated
! ! ! ! Concealed
Late Quaternary displacement (< 750,000 years)
Mapped Fault Location
Dashed were Approximated
! ! ! ! Concealed
Quaternary & unspecified displacement
(< 1,600,000 years)
undifferentiated Quaternary Well Constrained
undifferentiated Quaternary Moderately Constrained
! ! ! ! undifferentiated Quaternary Inferred
Pre-Quaternary geologic structures (CGS, 2010)
Mapped Fault Location
Dashed were Approximated
! ! ! ! Concealed
ANSS Earthquakes
Magnitude

4.0 - 4.9

4.9 - 5.9

5.9 - 6.9

6.9 - 7.9

7.9 - 8.9
125
Kilom
ete
r
R
a
diu
s
Project
Location
Willows fault
Thornton Arch
Stockton fault
East Valley fault
West Valley fault
Capay fault
Sweitzer fault
West Napa fault
Chabot fault
Serra fault
Lagoon Valley fault
Black Butte fault
Round Valley fault zone
Williams fault
Miller Creek fault
Antioch fault Corral Hollow fault
Hayward fault
Mohawk Valley fault
Rodgers Creek fault
Franklin fault
Dollar Point fault
Dog Valley fault
Clover Valley fault
Alexander fault
Greenville fault
Cross Spr ni g fault
Spenceville fault
Soda Creek fault
Pilarcitos fault
Wildcat fault
Cordelia fault
Crosley fault
Pinole fault
Etsel Ridge fault
Mocho fault
Maacama fault Maacama fault
Canada fault
Concord fault
Polaris fault
Calaveras fault
Rio Vista fault
Clayton fault
Mission fault
G ai nt Gap fault
Stoney Creek fault
Resort fault
Dunnigan Hills faul
H
t
ealdsburg fault
Bad Ridge fault
Pleasanton fault
Ione fault
Putah Creek
Cobb Mountain fault
Maidu East fault
Swain Ravine fault
Adobe Creek fault
Tolay fault
Green Springs Run fault
Chianti fault
Waters Peak fault
San Joaquin fault
Big Valley fault
Dewitt fault
San Jose fault
Poorman Gulch fault
San Andreas fault
Rescue fault
Seal Cove fault
Hunting fault
Bloomfield fault
Hot Springs Shear zone Vaca fault
Paynes Peak fault
Stanford fault
Youngs Creek fault
Corning fault
Vernalis fault
San Gregorio fault
Point Reyes fault
Midland fault
120°0'0"W
120°0'0"W
121°30'0"W
121°30'0"W
123°0'0"W
123°0'0"W
39°0'0"N
39°0'0"N
37°30'0"N
37°30'0"N
PROJECT NO:

CREATED:

CREATED BY:

CHECKED BY:

FILE NAME:

FIGURE
Quaternary Faults (Jennings and Bryant, 2010)
£
2/7/2024
ALeonard
F3_RegionalSeismic.mxd
Date: 2/7/2024 User: ALeonard Path: \\azrgisstorp03\GIS_Projects\Client\SAFCA\24001006.001A-ULDC_groundmotion\F3_RegionalSeismic.mxd

REGIONAL FAULTING

AND SEISMICITY
MRyan 3
0 20 40 80
Kilometers
The information included on this graphic representation has been compiled from a variety of sources and is subject to change without notice. Kleinfelder makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness, or rights to the use of such information. This document is not intended for use as a land survey product nor is it intended as a construction design document. The use or misuse of the information contained on this graphic representation is at the sole risk of the party using or misusing the information.

BASEMAP SOURCE:

Esri ArcGIS Online World Topography Map

SEISMIC EVALUATION GROUND MOTION

PARAMETER MEMORANDUM

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SACRAMENTO AREA FLOOD CONTROL AGENCY

LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
24001006.001A
Seismic Responsibility Reach
Faults, National Seismic Hazard Map
(NSHM), 2014
normal
strike slip
thrust
unassigned
Levee Alignment
32 5 K ilom ete r R adius
Pacific
Ocean
Project
Location
Duck F al t fault
Great Valley 12
Great Valley 02
Deep Springs
Dry
Mountain
Lost Hills
Fairview fault zone
Pittville 2011 CFM
M di d el gate fault zone
Last Chance
Round Valley
West Napa 2011 CFM
Great Valley 01
Antelope Valley 2011
Little Salmon (Offshore)
Airport Lake
Table Bluff
Greenville (No) 2011 CFM
Carson Range fault
Grass Valley fault zone
Zayante-Vergeles
West Tahoe
Hayward (So) 2011 CFM
Point Reyes 2011 CFM
Ortigalita (South)
Mohawk Valley 2011 CFM
Coaldale fault 1 Great Valley 07 (Orestimba)
Battle Creek 2011 CFM
Honey Lake 2011 CFM Ra ni bow Mounta ni fault zone Independence rev 2011 Pyramid Lake fault zone
Black Rock fault zone
Ione Valley fault
So Sierra Nevada
Hosgri
Russ 2011 CFM
Trinidad (alt1)
Rinconada 2011 CFM
Likely 2011 CFM
Buena Vista Valley fault zone Smith Valley fault
Eaton Roughs 2011 CFM
Hat Creek-McArthur-Mayfield
Owens Valley
White Mountains
Dixie Valley fault zone
Wassuk Range fault zone
San Andreas (Creeping Section) 2011 CFM
Mendocino
Reliz 2011 CFM
San Gregorio (North) 2011 CFM
San Andreas (Offshore) 2011 CFM
Bartlett Springs 2011 CFM
San Andreas (North Coast) 2011 CFM
Maacama 2011 CFM
118°30'0"W
118°30'0"W
120°0'0"W
120°0'0"W
121°30'0"W
121°30'0"W
123°0'0"W
123°0'0"W
124°30'0"W
124°30'0"W
40°30'0"N
40°30'0"N
39°0'0"N
39°0'0"N
37°30'0"N
37°30'0"N
36°0'0"N
36°0'0"N
£
Date: 9/21/2023 User: KHagan Path: \\azrgisstorp03\GIS_Projects\Client\SAFCA\24001006.001A-ULDC_groundmotion\F4_SeismicSource.mxd 0 50 100 200
Kilometers
BASEMAP SOURCE:

Esri ArcGIS Online World Topography Map
PROJECT NO:

CREATED:

CREATED BY:

CHECKED BY:

FILE NAME:

FIGURE
9/21/2023
KHagan
F4_SeismicSource.mxd

SEISMIC SOURCE MODEL
BASED ON UCERF3
MRyan 4 SEISMIC EVALUATION GROUND MOTION

PARAMETER MEMORANDUM

ULDC & FEMA LEVEE CERTIFICATION PROJECT

SACRAMENTO AREA FLOOD CONTROL AGENCY

LEVEE SYSTEMS

SACRAMENTO AND SUTTER COUNTIES, CALIFORNIA
24001006.001A
The information included on this graphic representation has been compiled from a variety of sources and is subject to change without notice. Kleinfelder makes no representations or warranties, express or implied, as to accuracy, completeness, timeliness, or rights to the use of such information. This document is not intended for use as a land survey product nor is it intended as a construction design document. The use or misuse of the information contained on this graphic representation is at the sole risk of the party using or misusing the information.

FILE NAME: CHECKED BY: DRAWN BY: DRAWN: PROJECT NO. UCERF3 Logic Tree UCERF3 SOURCE MODEL

LOGIC TREE
Seismic Evaluation Ground Motion Parameter Memorandum
ULDC & FEMA Levee Certification Project
Sacramento Area Flood Control Agency Levee Systems
Sacramento and Sutter Counties, California
24001006 09/20/2023 MRZZ
5 www.kleinfelder.com
FIGURE:

Fault Models Deformation Models
Scaling Relationships
(mag-area & sliplength relationships)
Slip Along Rupture
(Dsr)
Total M ≥5 Event
Rate (yr-1)
Inversion Model M off-fault
Off-Fault Spatial
Seismicity PDF (aka
SpatialPDF)
FM3.1 (0.5)
FM3.2 (0.5)
Boxcar (0.5)
Tapered (Sin½) (0.5)
Characteristic
UCERF2
Constrained (1.0)
EllsworthB
for both (0.2)
UCERF2 Smoothed
Seismicity (0.5)
Geologic
Deformation
Model (0.3)
Averaged Block
Model (0.1)
NeoKinema Model
(0.3)
Zeng-Shen
Model (0.3)
Hanks & Bakun
(2008) for both
(0.2)
Shaw (2009)
for both (0.2)
EllsworthB w/
Sqrt. Length
(0.2)
Shaw (2009)
w/ Constant Stress
Drop (0.2)

6.5 (0.1)

7.9 (0.6)

9.6 (0.3)

7.3 (0.1)

7.6 (0.8)

7.9 (0.1)
UCERF3 Smoothed
Seismicity (0.5)
max
24001006.001A/SAC23M158525_R2 February 9, 2024
© 2024 Kleinfelder www.kleinfelder.com
ATTACHMENT A1

SIGNIFICANT FAULTS INCLUDED IN SOURCE MODEL
___________________________________________________________________________________ Used in Used in Section
FM 3.1? FM 3.2? Mmax
3 Great Valley 03a Dunnigan Hills 27 20 3 6 TRUE TRUE 6.6 Great Valley 06 (Midland) 2011 CFM alt1 69 47 1 15 TRUE FALSE 7.3 Great Valley 04a Trout Creek 19 20 9 14 TRUE TRUE 6.6
Great Valley 03 Mysterious Ridge 51 20 9 14 TRUE TRUE 7.1 Great Valley 04b Gordon Valley 28 20 9 14 TRUE TRUE 6.8 Great Valley 06 Midland alt2 33 30 2 16 FALSE TRUE 7.2
Swain Ravine - Spenceville 103 60 0 12 TRUE TRUE 7.4
Great Valley 05 Pittsburg Kirby Hills alt2 32 90 10 20 FALSE TRUE 6.7 Great Valley 05 Pittsburg - Kirby Hills alt1 21 55 0 10.8 TRUE FALSE 6.6 Hunting Creek - Berryessa 2011 CFM 44 90 0 10.6 TRUE TRUE 6.9 Green Valley 2011 CFM 43 84 0 14 TRUE TRUE 7
Hunting Creek - Bartlett Springs connector 2011 38 90 0 12 TRUE TRUE 6.9 Los Medanos - Roe Island 21 39 0 14 TRUE TRUE 6.9
West Napa 2011 CFM 44 75 0 13.2 TRUE TRUE 7
Concord 2011 CFM 18 90 0 15 TRUE TRUE 6.6
Contra Costa (Lake Chabot) 2011 CFM 4 90 0 11.1 FALSE TRUE 5.9 Contra Costa Shear Zone (connector) 2011 CFM 30 81 0 12.9 TRUE FALSE 6.8 Clayton 16 90 0 16 TRUE TRUE 6.6
Contra Costa (Dillon Point) 2011 CFM 11 90 0 12.5 FALSE TRUE 6.3 Contra Costa (Vallejo) 2011 CFM 4 77 0 11 FALSE TRUE 5.8 Contra Costa (Ozal - Columbus) 2011 CFM 9 90 0 13.2 FALSE TRUE 6.3 Great Valley 02 22 15 7 9.6 TRUE TRUE 6.5
Franklin 2011 CFM 38 90 0 13.2 TRUE TRUE 6.9
Contra Costa (Southampton) 2011 CFM 11 80 0 14 FALSE TRUE 6.4 Contra Costa (Briones) 2011 CFM 9 90 0 12.9 FALSE TRUE 6.3 Greenville (No) 2011 CFM 51 84 0 14.9 TRUE TRUE 7.1
Collayami 2011 CFM 35 90 0 10 TRUE TRUE 6.7
Contra Costa (Larkey) 2011 CFM 8 90 0 15 FALSE TRUE 6.3 Contra Costa (Reliez Valley) 2011 CFM 6 90 0 14.7 FALSE TRUE 6.1 Bennett Valley 2011 CFM 33 90 0 10 TRUE TRUE 6.7
Mount Diablo Thrust North CFM 19 40 1 13.5 TRUE FALSE 6.8 Contra Costa (Lafayette) 2011 CFM 8 90 0 14.6 TRUE TRUE 6.3 Rodgers Creek - Healdsburg 2011 CFM 82 77 0 12 TRUE TRUE 7.3 Mount Diablo Thrust 25 38 8 16 FALSE TRUE 6.7
Hayward (No) 2011 CFM 53 82 0 11.1 TRUE TRUE 7
Bartlett Springs 2011 CFM 164 90 0 14.5 TRUE TRUE 7.6
Calaveras (No) 2011 CFM 48 80 0 14 TRUE TRUE 7
Maacama 2011 CFM 175 63 0 10.9 TRUE TRUE 7.6
Great Valley 07 (Orestimba) 66 20 7 9.6 TRUE TRUE 7
Great Valley 01 44 15 7 9.6 TRUE TRUE 6.8
Mount Diablo Thrust South 11 40 1 13.5 TRUE FALSE 6.5
Hayward (So) 2011 CFM 54 76 0 13.4 TRUE TRUE 7.1
San Andreas (North Coast) 2011 CFM 171 90 0 11 TRUE TRUE 7.5 FAULT SECTION ID Length
(km)
Ave Dip
(Deg)
Upper Seis.

Depth (km)
Lower Seis.

Depth (km)
24001006.001A/SAC23M158525_R2 February 9, 2024
© 2024 Kleinfelder www.kleinfelder.com
ATTACHMENT A2
CALCULATION PACKAGE – SHEAR WAVE VELOCITY AND SITE PARAMETERS ___________________________________________________________________________________ Project Name: SACFA ULDC/FEMA
Project Number: 24001006.001A
Revision History:

Version Analyzed By Date Reviewed By Date
0 M. Ryan 9/13/2023 Zia Zafir 9/14/2023
References:

Initial Evaluation
Purpose:

Analysis Type:

Site specific seismic hazard analysis for SAFCA ULDC/FEMA levee certification HAZ for PSHA
Notes
See Report and updated model sheet for results
Site characterization only in this sheet
KLF No. 24001006.001A
Latitude 36.652563
Longitude -121.811094
Background Information:

Summary:

Site-Specific Site Characteristics
Vs30 (m/s) Z1 (m) 1
Z2.5 (km) 2
335 0.428 1.55
Notes

1. Per Abrahamson-et al (2014) NGA West 2

2. Per Campbell-Bozorgnia (2014) NGA West 2
Vs30 estimated for stiff soils, typically occuring at depth of about 100 to 120ft below ground surface; consistent with analysis by URS for previous certification in 2007
Z1.0 and Z2.5 considered using NGA W2 relationships - justification per Petersen et al. 2019 NGA W2
(HAZ code uses Z1.0 and Z2.5 in km,
values used shown above)
24001006.001A/SAC25R179413 April 16, 2025
© 2025 Kleinfelder

APPENDIX B

GROUND MOTION PARAMETER SELECTION MEMORANDUM
_____________________________________________________________________ 24001006.001A/SAC24M163970 Page 1 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701

SEISMIC EVALUATIONTECHNICAL APPROACH MEMORANDUM
DATE: February 8, 2024
TO: Mr. Pete Ghelfi, PE
Director of Engineering
Sacramento Area Flood Control Agency
1325 J Street, Suite 1700
Sacramento, CA 95814
FROM: Ryan Hochstatter, EIT
Zia Zafir, PhD, PE, GE
SUBJECT: Seismic Evaluation Technical Approach Memorandum ULDC & FEMA Levee Certification Project
Sacramento Area Flood Control Agency Levee Systems
Sacramento and Sutter Counties, California
___________________________________________________________________________________ 1 INTRODUCTION
Kleinfelder has been tasked by the Sacramento Area Flood Control Agency (SAFCA) with evaluating the seismic vulnerability of the Sacramento area levees located in Sacramento and Sutter Counties, California as shown on Attachment 1. This technical approach memorandum presents the methodology for the seismic evaluation consistent with the Urban Levee Design Criteria (ULDC) (DWR, May 2012) and the Urban Levee Evaluations Project Guidance Document for Geotechnical Analysis (DWR Guidance Document) (DWR and URS, 2015).

This memorandum has been prepared consistent with the requirements of the approved scope of work for the subject project outlined in Kleinfelder’s proposal dated May 5, 2023. 2 PURPOSE
SAFCA is working with a team of consultants to obtain ULDC and Federal Emergency Management Agency (FEMA) certifications for the Sacramento area levees. The purpose of this document is to establish a seismic vulnerability evaluation methodology that conforms to ULDC. Methodology will generally follow seismic vulnerability guidelines for intermittently-loaded levees as described in the DWR Guidance Document (DWR and URS, 2015). The results of the seismic vulnerability evaluation will be used to evaluate the seismic vulnerability for FEMA certification.

The levees will be organized by selection of “sections” instead of reaches due to the variable nature of subsurface conditions under levees. Sections may overlap multiple reaches or reaches may be subdivided into multiple sections. Note that for sections encompassing or divided by roadway overcrossings, the overcrossings will be simplified to their centerlines, and additional improvements to the levee for overcrossing abutments will be neglected. 24001006.001A/SAC24M163970 Page 2 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 3 PROJECT FEATURES
Attachment 1, Seismic Planning Services Responsibility Map, shows the following levee systems and their associated component levees. The levee systems are summarized in Table 1 below.

Table 1: Levee Systems and Component Levees
Levee System Reach
1 - Dry Creek Dry Creek North Levee
2 - Robla-Arcade
Dry Creek South / Robla Levee
Natomas East Main Drainage Canal (NEMDC) East Levee - Robla to Arcade Creek Arcade Creek North Levee
3 - American North
Arcade Creek South Levee
NEMDC East Levee - Arcade Creek to American River
American River North Levee
4 - American South
American River South Levee
Sacramento River East Levee (SREL) - American River to NBLL North Beach Lake Levee
5 - Natomas Basin
Natomas Cross Canal South Levee (NCC)
SREL - NCC to Powerline Road
SREL - Powerline Road to American River
American River North Levee - Sacramento River to NEMDC
NEMDC West Levee
Pleasant Grove Creek Canal (PGCC) West Levee
4 GOVERNING STANDARDS
Methodology for conducting seismic vulnerability evaluation of levees is governed by design criteria developed by the California Department of Water Resources (DWR). Relevant publications that will be the primary source for Kleinfelder’s analysis includes:
• Urban Levee Design Criteria (ULDC, 2012) “Section 7.7 – Seismic Vulnerability” • Urban Levee Evaluations Project Guidance Document for Geotechnical Analysis (ULE, 2015), DWR and URS, “Section 6.0 – Seismic Analysis” - included as Attachment 3 Additionally, ground motion parameter development for evaluations is governed by applicable US Army Corps of Engineer’s Regulations and Manuals (ER & EM). Design guidance applicable to the seismic evaluation includes:
• Engineering Manual (EM) 1110-2-1913 (April 2000, USACE) “Design and Construction of Levees” 24001006.001A/SAC24M163970 Page 3 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 • Engineer Regulation (ER) 1110-2-1806 (May 2016, USACE) “Earthquake Design and Evaluation for Civil Works Projects”
• Engineering and Design Technical Letter (ETL) 1110-2-580 (March 2013, USACE) “Guidelines for Seismic Evaluation of Levees”
5 SESIMIC VULNERABILITY EVALUATION WORKFLOW
An overview of the seismic vulnerability evaluation workflow is shown on Attachment 2. The seismic vulnerability evaluation workflow was adapted from the DWR seismic vulnerability evaluation as a part of the DWR ULDC Guidance Document included as Attachment 3. Three stages of evaluation are identified as:

1. Preliminary Work

2. Phase 1: Screening Review of Existing Analysis

3. Phase 2: Targeted Evaluation
Each stage is discussed in greater detail in the sections below.

5.1 Preliminary Work and Methodology for Developing New Peak Ground Accelerations The existing geotechnical analysis and subsurface data will be reviewed to identify the seismic segments.

During this process, any data gaps will be identified, and an updated peak ground acceleration (PGA) and earthquake magnitude will be established.

5.1.1 Existing Ground Motion Data
Previous development of ground motion parameters in the area was performed by URS in 2007 as part of the Delta Risk Management Strategy (DRMS), which was updated and expanded on in 2012 by URS as part of the Department of Water Resources’ (DWR) Urban Levee Evaluation (ULE) project. A 200-year return period seismic hazard map was developed for the ULE area, which encompasses the ULDC area.

The probabilistic seismic hazard analysis performed for the ULE area was based on the UCERF2 seismic source characterization. The ground motion parameters developed by URS consisted of peak horizontal acceleration for soil/rock condition at a depth of 300 feet below the ground surface. In addition, associated earthquake magnitude was also estimated.

For this project the source characterization by others will be reviewed, where high-quality peer reviewed seismic source models are available. This will include studies performed by the United States Geological Survey applicable to the project region (e.g. Petersen et al. 2014, 2019), statewide studies performed as part of the third Uniform California Earthquake Rupture Forecast (UCERF3 - Field et al., 2013). It is expected the UCERF3 characterization will be primarily used for this project due to its wide adoption in other work and for consistency with the deprecated UCERF2 model used in previous work by URS. Additionally, Petersen et al. (2014, 2019) models will be used for far-field seismic sources outside of California (e.g. Cascadia, etc.)
24001006.001A/SAC24M163970 Page 4 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 Analysis performed by URS in 2012 for ULE identified several potential seismic sources in the area that were not included in the UCERF2 model (i.e. Northern Midland fault zone). The UCERF3 model will be evaluated for inclusion of these sources.

Following evaluation of existing design ground motion data, segments of levee with either non-existent or out-of-date seismic data will be analyzed according to procedures described below.

5.1.2 Probabilistic Seismic Hazard Analysis (PSHA)
The PSHA approach that will be used to estimate the ground motion parameters (typically peak ground and spectral ground accelerations) is generally consistent with requirements of ULDC, with some modifications in implementation based on current standards of practice for probabilistic evaluations in California (e.g. “Grand Inversion” approach). The probabilistic approach is used in place of a deterministic approach as permitted by ER 1110-2-1806 §7d.

The PSHA uses a logic tree approach to account for epistemic uncertainty in the model, with aleatoric variability accounted for in the uncertainty associated with various models (e.g. GMM’s). The logic tree is developed to account for uncertainties in the source models, ground motion models, and other items impacting the results. Important source characteristics include slip rates and fault lengths, magnitude and recurrence intervals of potential seismic events, distance from the site to the causative source, and other parameters. The effects of site soil conditions, and other considerations such as basin effects, can be accounted for using ground motion models (GMMs).

𝑃𝐸
(𝑧) = 1 −𝑒𝑥𝑝 𝑒𝑥𝑝 (−𝑣(𝑧) ∗ 𝑡)
Different probabilities of exceedance may be selected, depending on the level of performance required.

The return period is essentially equivalent to the reciprocal of v(z).

The PSHA is conducted using three generalized steps that include the following. 24001006.001A/SAC24M163970 Page 5 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701

1. Development of an appropriate seismic source model including source characterization, development of recurrence relationships, and appropriately capturing uncertainty

2. Selection of appropriate ground motion models (and site amplification models, if appropriate)

5.1.3 Seismic Source Model
The seismic source model for a site contains all information required to characterize potential seismic sources for use in evaluation of ground motion parameters. The source model typically includes information on the geometry (e.g. length, dip, depth, etc.), style of faulting, magnitude, and recurrence relationships for all potentially active seismic sources within a distance capable of significantly impacting a site. The source model used for this work is discussed below.

5.1.4 ‘Grand Inversion’ and Recurrence Rates
The earthquake recurrence rates used in the source model will be adopted as developed by the UCERF3 project, as implemented by Petersen et al. (2019) using the branch-averaged solutions of the ‘grand inversion’. This is a departure from the older standard of practice documented in EM 1110-2-6053 and Draft EM 1110-2-6000, which solves for the entire system of faults within California simultaneously.

The ‘grand inversion’ scheme developed by the UCERF3 project team, the results of which will be adopted in this work, ‘solved’ the on-fault and off-fault recurrence rates at a system level using a set of defined constraints including the spatial probability density of off-fault seismicity, slip rate balancing, paleoseismic even rate matching, fault smoothness constraint, regional magnitude frequency distribution constraints, and fault section specific magnitude frequency distribution constraints. In simple terms the ‘grand inversion’ solves for three things: large on-fault (supra-seismogenic) event rates; small, near-fault (subseismogenic) event rates; and truly off-fault (unassociated) event rates. The 24001006.001A/SAC24M163970 Page 6 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 supra-seismogenic ‘on-fault’ events are ultimately modeled using linear fault sources while the latter two categories (subseismogenic and off-fault) are considered ‘background seismicity’ and are modeled using spatially smoothed ‘grid’ of evenly spaced cells (a.k.a. gridded seismicity). The combined on-fault and off-fault solution set (fault system solution) used the logic tree solution framework shown in a generalized form on Attachment 4. Our model implements the branch-averaged solutions.

The on-fault seismicity considers two potential alternative fault models, equally weighted, identified as fault model 3.1 (FM 3.1) and fault model 3.2 (FM 3.2). These fault models each contain a slightly different collections of fault traces that are broken into ‘segments’ for modeling purposes, with individual segments strung together during evaluation to create hundreds of thousands of potential fault-based ruptures or multi-rupture events. In our model, fault segments are modeled with the recurrence rates constrained during the ‘grand inversion’ by the UCERF2 ‘characteristic’ inversion branch (e.g. Schwartz and Coppersmith, 1984). Fault slip rates (deformations) are constrained by a combination of a ‘pure’ geologic deformation model and three other models that consider geologic and geodetic data including the average fault block model, NewKinema model, and Zeng-Shen model. The magnitude-area relationships used along with the associated slip-length models, as well as other solution constraints applied, are shown with weights on Attachment 4 and are discussed in detail in Field et al. (2013) and associated publications.

Off-fault seismicity (e.g. background seismicity) recurrence rates are solved for simultaneously by the ‘grand inversion’. This off-fault background seismicity is intended to include all smaller earthquakes (Mw<~6.5) on major faults and earthquakes of all sizes that are not associated with known faults. The off-fault background seismicity considers spatial smoothing of a ‘grid’ of evenly spaced cells using the spatial probability density function (PDF) grids of off-fault seismicity from UCERF2 and UCERF3 (equally weighted), considering the regional constraints on the model including the total regional magnitudefrequency distribution (e.g. Gutenberg-Richter distribution), maximum off-fault magnitude, number of regional events per year greater than Magnitude 5, and other constraints as shown on the logic tree (see Attachment 4). The branch-averaged, gridded seismicity solution for each fault model, as implemented by Petersen et al. (2019), was used in the source model for this work.

5.1.5 Ground Motion Model’s (GMM’s)
This study makes use of response spectral attenuation relationships, also known as ground motion models (GMMs), in evaluations at the site as required by ER 1110-2-1806.

Site-specific ground motions can be influenced by the styles of faulting, magnitudes of the earthquakes, and local soil conditions. Other effects such as near-source or basin effects can also influence the ground motions. The GMM’s used to estimate ground motion from an earthquake source need to directly or 24001006.001A/SAC24M163970 Page 7 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 indirectly consider these effects. Many GMMs have been developed to estimate the variation of spectral acceleration with earthquake magnitude and distance from the site to the source of an earthquake.

The Idriss (2014) model has not been used as it is not valid at the larger distances used in this study (e.g. more than 150 km). The far-field subduction events (e.g. from Cascadia megathrust) were modeled using the relationships of Atkinson and Macias (2009), Abrahamson et al. (2016), and Zhao et al. (2006) with equal weights applied, except that for slab events the Atkinson and Macias (2009) relationship was excluded. Spectral acceleration values are obtained by averaging the individual hazard results. These GMM’s provide ‘mean’ (RotD50) values of ground motions associated with magnitude, distance, site soil conditions, and mechanism of faulting. The uncertainty in the predicted ground motion was taken into consideration by including a magnitude dependent standard error in the probabilistic analysis.

5.1.6 Control Points and Site Parameters
Evaluation of seismic hazard and model development for site specific studies is usually completed at a control point considered representative of a structure or facility. For this project, multiple control points along levee alignments will be considered for evaluation of seismic hazard for the levees associated with this project. Points along levee alignment are considered adequate as active faults are generally located at distance from the site, and thus, small differences due to control point location variation should be minimal. Spacing between control points will vary based on soil conditions and mapped accelerations, with maximum spacing of 1 km (3280 ft). The control points will be used in evaluation of distance terms (rx, rjb, rrup) required for the selected GMM’s.

The value of VS30 will be evaluated based on data from previous reports. Ground motions will be evaluated at the ground surface and consider average or best estimate shear wave velocity profiles applicable to the levee under consideration, without modification to the ground motions due to soft clay and liquefied soil response. Z1.0 and Z2.5 will be developed considering various geologic factors and estimates from the NGA West 2 correlations to develop best estimate values.

5.2 PHASE 1: SCREENING REVIEW OF EXISTING ANALYSIS
The purpose of the screening process is to identify sections where original analyses are determined to be deficient, and sections where updated analyses indicate potential deformation where original analyses did not.

Sections determined to be non-critical for seismic performance will not be used in analyses or presented in report.
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KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 Newly developed PGA’s for critical sections will be compared to PGA’s from previous reports. If the new PGA value and associated earthquake magnitude are lower than the original values and the original analysis is found to be adequate, no further analysis is required for that section. If the original analysis determined the section is not susceptible to deformation, no further analysis is required, unless new PGA and/or earthquake magnitude show significant liquefaction susceptibility. Additionally, if the section was found to be failing in Flow Failure or High Vulnerability based on original PGA and earthquake magnitude, no further analysis will be required.

5.3 PHASE 2: TARGETED EVALUATION
The purpose of targeted evaluation is to determine susceptibility to deformation based on updated parameters.

A targeted evaluation is required for critical sections under two conditions, as follows:

1. The new PGA and earthquake magnitude is less than or equal than the original PGA, the original analysis is determined to be inadequate, and the Flow Failure factor of safety (FOS) with original PGA is greater or equal to 1

2. The new PGA and/or earthquake magnitude is greater than the original PGA, the original analysis or conditions classify the section as low or moderate vulnerability, and the Flow Failure FOS with original PGA is greater than 1
If the targeted section meets ULDC criteria, no further analysis is required. If the section does not meet ULDC criteria, Flow Failure and deformation must be analyzed using new seismic values. Flow Failure FOS and deformation results will be presented in Kleinfelder’s report and used in the development of the Seismic Performance Summary Report and Post-Earthquake Remediation Plan. 6 METHODOLOGY FOR EVALUATING SEISMIC VULNERABILITY
Seismic vulnerability evaluation will follow the guidance provided in DWR Guidance Document (DWR and URS, 2015). High, Moderate, and Low Vulnerability classifications will be based on the seismic deformation estimates. As mentioned earlier, all sections classified as High Vulnerability in the Phase 1 and Phase 2 screening process will not be analyzed.

The following steps are involved in assessing seismic vulnerability, Step numbers are associated with Key Steps described in Figure 1, Table 6-1 of the DWR Guidance Document (DWR and URS, 2015); see Attachment 2 for the workflow chart.

1. Perform liquefaction analysis using revised PGA and earthquake magnitude values using URS spreadsheets to delineate zones of liquefaction.

Based on the results of liquefaction, identify any additional cross section for analysis. We will be using the cross sections already developed for our previous studies. 24001006.001A/SAC24M163970 Page 9 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701

2. For selected cross sections, estimate FOS against flow failure using residual strength for liquefiable materials and performing static slope stability analysis. If FOS is less than 1, the section is classified as “High Vulnerability” and no further analysis is needed.

If FOS against flow failure is greater than 1.3, section will be classified as “Low Vulnerability”, unless analysis for volumetric strain results in a higher vulnerability class.

Kleinfelder has previously performed extensive slope failure modeling along the levee alignments using SLOPE/W, a two-dimensional finite element computer modeling, a package included in the GEOSTUDIO software package, which is developed by Bentley Systems, Inc. It is anticipated that those models will be updated to the current version of GEOSTUDIO (2023.1.0) and utilized for Targeted Flow Failure analyses. New analyses may need to be developed on an as-needed basis. Idealized soil properties will be based on previous investigations and generalized parameters from DWR Guidance Document (DWR and URS, 2015). Water surface elevations for seismic flow failure analyses will be the higher of either average summer or average winter water surfaces, in accordance with DWR Guidance Document (DWR and URS 2015).

Slope failure analyses should consider all potential failure modes, including:
• Waterside and landside
• Deep and shallow
• Circular and wedge-shaped

3. If FOS against flow failure is between 1.0 and 1.3, a simplified seismic deformation analysis should be performed on the section. This involves computing a maximum horizontal seismic coefficient (Kmax) and performing a pseudo-static stability analysis using a horizontal seismic coefficient of 50% of the maximum value. This analysis will be performed using the same updated SLOPE/W models used in Step 2. If the resulting FOS is greater than 1.0, the section may be classified as “Low Vulnerability”.

Yield acceleration (Ky) values must then be estimated using pseudo-static analyses using the same SLOPE/W models used in Step 2. Yield acceleration is defined as the minimum horizontal acceleration resulting in a just-stable slope condition, i.e. FOS = 1.0. Yield acceleration should be developed for each potential failure mode.

A vertical Newmark-type deformation analysis should be performed based on the Kmax and Ky values determined above. The calculated Newmark displacement may be reduced by 30% for estimation of freeboard loss.

Volumetric settlement should be considered for sections with potentially liquefiable soils thicker than 20ft. Previous work performed by URS on ULE considered (N1)60-cs blow counts less than 15 as liquefiable and subject to volumetric settlement. This blow count criteria will be evaluated against new research and revised if necessary.
24001006.001A/SAC24M163970 Page 10 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 Seismic vulnerability classification is determined by calculating freeboard loss as the sum of Newmark-type vertical deformation and volumetric settlement (if applicable). Freeboard loss is evaluated as a percentage of levee height (as measured from hinge point on the landside toe).

Engineering judgment should be used to determine damage to internal levee structures, and the seismic vulnerability class should be evaluated based on Table 6-1 from the DWR Guidance Document (URS and DWR, 2015) shown below.

Figure 1: Table 6-1 from DWR Guidance Document, Section 6.4

4. Advanced seismic deformation analyses as described in Attachment 2 are applicable only to frequently loaded levees and will not be considered for this analysis. 7 LIMITATIONS
This work was performed in a manner consistent with that level of care and skill ordinarily exercised by other members of Kleinfelder’s profession practicing in the same locality, under similar conditions and at the date the services are provided. The work performed was based on project information provided by client. Kleinfelder’s conclusions, opinions, and recommendations are based on a limited number of observations and data. It is possible that conditions could vary between or beyond the data evaluated.

Kleinfelder makes no other representation, guarantee, or warranty, express or implied, regarding the services, communication (oral or written), report, opinion, or instrument of service provided.

This report may be used only by the client and the registered design professional in responsible charge and only for the purposes stated for this specific engagement within a reasonable time from its issuance, but in no event later than two years from the date of the report.

Conclusions contained in this report are based on review of existing information referenced in this report and Kleinfelder’s present knowledge of the project. It is possible conditions could vary from that contained in those documents. If conditions are encountered that differ from those described herein, the client is responsible for ensuring that Kleinfelder is notified immediately so that we may reevaluate the conclusions of this report.
24001006.001A/SAC24M163970 Page 11 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 The scope of services was limited. It should be recognized that definition and evaluation of subsurface conditions are difficult. Judgments leading to conclusions and recommendations are generally made with incomplete knowledge of the subsurface conditions present due to the limitations of data from field studies. The conclusions of this assessment are based on the information presented herein.

Although risk can never be eliminated, more detailed and extensive studies yield more information, which may help understand and manage the level of risk.

All rivers, streams and lakes will flood eventually. This fact means that all levees will be called upon to combat floodwaters at some point. Levees reduce the risk of flooding. But no levee system can eliminate all risk of flooding. The term “certification” is not intended to provide a guarantee or warranty of the conditions of the levee or its performance and assumes the following 1) a certification by a registered professional engineer or other party does not constitute a warranty or guarantee of performance, expressed or implied; 2) certification of data is a statement that the data is accurate to the best of the certifier’s knowledge; and 3) certification of analyses is a statement that the analyses have been performed correctly and in accordance with sound engineering practices. A levee certification does not address or mitigate the inherent flood risk proposed to a particular community. 8 CLOSING
This seismic evaluation technical approach memorandum is for review by the subject project’s peer review panel for concurrence with the approach for the forthcoming site-specific ground motion hazard analysis. If you have questions regarding this memorandum or if we may be of further assistance, please contact the undersigned.

Sincerely,
KLEINFELDER, INC.

Ryan Hochstatter, EIT Zia Zafir, PE, GE
Staff Geotechnical Engineer Sr. Principal Geotechnical Engineer

ATTACHMENTS
Levee Systems and Component Levee Map
Seismic Workflow
Seismic Vulnerability Analysis – Key Steps (DWR Guidance Document, 2015, DWR and URS) UCERF3 Source Model Logic Tree
24001006.001A/SAC24M163970 Page 12 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701

Abrahamson, N.A., Silva, W.J., and Kamai, R. (2014). “Summary of the ASK14 Ground Motion Relation for Active Crustal Regions.” Earthquake Spectra, Vol. 30, No. 3, pp. 1025-1056.

California Department of Water Resources (DWR) (2012). Urban Levee Design Criteria.

Cornell, C.A. (1968). Engineering Seismic Risk Analysis, Bulletin of the Seismological Society of America, Vol. 58, No. 5.

Cornell, C.A. (1971). Probabilistic Analysis of Damage to Structures Under Seismic Loading, Dynamic Waves in Civil Engineering, London, Interscience.

Field, E.H., Biasi, G.P., Bird, P., Dawson, T.E., Felzer, K.R., Jackson, D.D., Johnson, K.M., Jordan, T.H., Madden, C., Michael, A.J., Milner, K.R., Page, M.T., Parsons, T., Powers, P.M., Shaw, B.E., Thatcher, W.R., Weldon, R.J., II, and Zeng, Y. (2013). The Uniform California Earthquake Rupture Forecast, Version 3 (UCERF 3), USGS Open File Report 2013-1165, CGS Special Report 228, Southern California Earthquake Center Publication 1792, http://pubs.usgs.gov/of/2013/1165/.

Idriss, I. M. (2014). “An NGA-West2 Empirical Model for Estimating the Horizontal Spectral Values Generated by Shallow Crustal Earthquakes.” Earthquake Spectra, Vol. 30, No. 3, pp. 1155-1177.

Merz, H.L. and Cornell, C.A. (1973). Seismic Risk Analysis Based on a Quadratic Magnitude-Frequency Law, Bulletin of the Seismological Society of America, Vol. 63, No. 6.

Powers, P.M. (2017). National Seismic Hazard Model Project Computer Code (NSHMP-HAZ) Software, https://doi.org/10.5066/F7ZW1K31.
24001006.001A/SAC24M163970 Page 13 of 13 February 8, 2024 © 2024 Kleinfelder www.kleinfelder.com
KLEINFELDER 3130 Kilgore Road, Suite 200, Rancho Cordova, CA 95670 p | 916.366-1701 Schwartz, D.P. and Coppersmith, K.J. (1984). Fault Behavior and Characteristic Earthquakes: Examples from the Wasatch and San Andreas Fault Zones, Journal of Geophysical Research, Vol. 89, pp. 5681-5698.

URS (2015b). “Guidance Document for Geotechnical Analyses, Urban Levee Geotechnical Evaluations Program, Contract 4600008101,” dated April 2015.

United States Army Corps of Engineers (USACE). (1999). Engineering Manual (EM) 1110-2-6050 “Response Spectra and Seismic Analysis of Concrete Hydraulic Structures.” USACE (2000). Engineering Manual (EM) 1110-2-1913 “Design and Construction of Levees.” USACE (2013). Engineering and Design Technical Letter (ETL) 1110-2-580 “Guidelines for Seismic Evaluation of Levees.”
USACE (2016). Engineer Regulation (ER) 1110-2-1806 “Earthquake Design and Evaluation for Civil Works Projects.”
Zhao et al. (2006). Attenuation Relations of Strong Ground Motion in Japan using Site Classification Based on Predominant Period. Bulletin of the Seismological Society of America, V. 96, No. 3, pp. 898-913.

Yolo
Bypass
Fremont
Weir
Sacramento
Weir
w
Natomas
Cross Canal
NEMDC
River
Natomas
Basin
American
h
Sacramento
[
Folsom
Lake
Folsom
Arcade
Creek
Roseville
Dry Creek
Mo
rris
on
Creek
Strawberry
Creek
Natomas Levees
Folsom Dam Joint Federal Project
(Auxiliary Spillway)
North Area
Streams Levees
South Sacramento
Streams Group Levees
American River
Levees
Sacramento River Levees
South of Confluence
Sacramento
River
tu50
|ÿ70
§¨¦I-80
|ÿ99
§¨¦I-5
|ÿ99
|ÿ160
§¨¦I-80
PLACER
COUNTY
SUTTER
COUNTY
:

Legend
Federal Project Leveeor StructureNon Project Levee
0 3.5 1.75
Scale in Miles
SAFCA Flood Control
System Features

KLEINFELDER SEISMIC RESPONSIBILITY REACH
North Beach Lake
Levee
ATTACHMENT B: Seismic Planning Services Responsibility Map Proposal For Geotechnical Engineer & Seismic Planning Services ULDC & FEMA Levee Certification Program
Sacramento Area Flood Control Agency Levee Systems
Sacramento and Sutter Counties, California
1 2
Phase 1: Screening Review of Existing Analysis
Yes No Yes No No Yes Yes No NO FURTHER

ANALYSIS

NO FURTHER

ANALYSIS
Yes No Critical Section for
Reach Seismic
Performance? Phase 2: Targeted Evaluation
Original Analysis Or
Conditions Indicate
Susceptible to
Deformation*?
Original Analysis
Adequate? Original PGA>
New PGA
Flow Failure
(FOS<1) with
Original PGA? Yes No
Preliminary Work Flow Failure
(FOS<1)?
Coordinate on
Impacts
No Yes NO FURTHER
ANALYSIS Revise Reach
Limits if Needed
Report
Deformation &
Results

TARGETED

EVALUATION

REQUIRED

Preliminary
Selection of
Seismic Segments
Data Gap Analysis
and Obtain Original
Results
Meet with IPE to
Establish Criteria
Evaluate new PGA
and Magnitude Non-critical section/analysis results not presented or used ATTACHMENT 2: Seismic Evaluation Workflow Chart
Proposal For Geotechnical Engineer & Seismic Planning Services ULDC & FEMA Levee Certificaiton Program
Sacramento Area Flood Control Agency Levee Systems
Sacramento and Sutter Counties, California
Figure
6-1
Seismic Vulnerability Analysis – Key Steps

URBAN LEVEE EVALUATIONS
Department of Water Resources
Division of Flood Management
Step 2: Perform Post-Seismic Stability Analysis
Step 3f: Calculate volumetric strain, if necessary
Step 3a: Compute Kmax using Figure 6-4
Step 3e: Estimate vertical deformation as 0.7 times total Newmark displacement
Step 3g: Assign seismic vulnerability class using Table 6-1 Step 3c: Compute Ky value for sliding mass
Step 3d: Compute Newmark displacement using Kmax, Ky, and Figure 6-5 Yes
Step 3b: Perform pseudo-static stability analysis using K=0.5 Kmax No
Classify as “Low Vulnerability” unless
Volumetric Strain (Step 3f ) results in a
higher vulnerability class
Is
FSPS < 1?
Yes
No
Perform post-seismic stability analysis
Continue to Step 3
No further analysis is needed.

6.5 (0.1)

7.9 (0.6)

9.6 (0.3)

7.3 (0.1)

7.6 (0.8)

APPENDIX C
SECTION 6, SEISMIC ANALYSIS, GUIDANCE DOCUMENT FOR GEOTECHNICAL ANALYSES, URBAN LEVEE

EVALUATIONS PROJECT
_____________________________________________________________________

GUIDANCE DOCUMENT
for Geotechnical Analyses
Urban Levee Evaluations Project
Contract 4600008101
April 2015
Prepared for:

DEPARTMENT OF WATER RESOURCES
Division of Flood Management
3464 El Camino Avenue, Suite 200
Sacramento, CA 95821
Prepared by:
2870 Gateway Oaks Drive, Suite 150
Sacramento, CA 95833
SECTION 6.0 SEISMIC ANALYSIS

6.0 SEISMIC ANALYSIS
The simplified screening-level seismic vulnerability assessment procedures presented in this section were developed specifically for the geologic and seismic conditions of ULE study areas. This procedure may not apply to other regions where geology, levee configurations, or intensity and durations of shaking differ from ULE study areas. A large number of abbreviated terms are used in this seismic analysis section. See the list of acronyms and abbreviations in the Table of Contents for definitions of terms.

This section presents general guidelines for performing a screening-level seismic vulnerability analysis for levees in the Sacramento and San Joaquin river systems.

Guidelines are presented for performing soil liquefaction triggering analysis, post-seismic slope stability analysis, and, as necessary, seismic deformation analyses and using the results from these analyses to then assign a seismic vulnerability class to each levee segment, or part thereof, in a study region.

ULE analysts should perform seismic vulnerability analyses using a 200-year return period seismic event and the higher of either the average summer or winter WSE. The flow chart shown in Figure 6-1 illustrates the general process for performing seismic vulnerability analyses for ULE intermittently-loaded levees. Intermittently-loaded levees are defined in ULDC1 (DWR, 2012) as levees that do not experience a water surface elevation of 1 foot or higher above the elevation of the landside levee toe at least once a day for more than 36 days per year on average. Intermittently-loaded levees have been identified as being present in the Urban study areas and the liquefaction triggering analyses and seismic vulnerability analyses results for these levees will be presented in each study area’s GER in Volume 2.

The purpose of the seismic vulnerability analysis is to estimate vertical deformation, which is then used to assign a seismic vulnerability class to a seismic segment (Table 6-1). The seismic segment(s) and analysis cross section(s) should be selected based on liquefaction triggering analysis results, available topography and bathymetry, distance to river/channel, levee geometry, and existing and/or planned mitigation measures. The seismic vulnerability analysis sections representing levee segments with potential liquefaction may be selected independent of reaches evaluated for static conditions and could be representative of multiple reaches or segments.

For levee segments assessed as having liquefiable layers, two conditions may exist: the segment may meet all static ULE criteria, or the segment may require one or more static remedial alternatives. For those segments meeting all static ULE criteria, ULE analysts should perform a seismic vulnerability analysis as described in this section under existing conditions for the segment. For those segments requiring one or more static remedial alternatives, those alternatives must meet ULE criteria, and will be verified and assumed to be in place prior to performing seismic vulnerability analysis. ULE analysts should then perform seismic vulnerability analyses under applicable static conditions (i.e., either existing conditions, or ULE’s selected static remedial alternative). 1 See Appendix C for the Urban Levee Design Criteria (ULDC) (DWR, 2012). 20150427_GuidanceDoc.docx 6-1 Issue Date: April 2015

SECTION 6.0 SEISMIC ANALYSIS
For the frequently-loaded levees which are present in several Urban-Non-Project study areas, ULE analysts should use the guidance defined in ULDC (DWR, 2012) Sections 7.6 and 7.7.2, and the protocol presented in Section 6.11 will be followed. The seismic vulnerability evaluation will be performed under existing conditions and presented in Volume 1 of the GERs. For frequently-loaded levee segments that do not meet seismic vulnerability criteria, seismic remedial alternatives will be identified, evaluated, costed, and presented in Volume 2 of the GERs. Remediation for seismic vulnerability is only performed for frequentlyloaded levees.

The overall methodology for seismic evaluations is based on a study by the Seismic Evaluation and Methodology Group as described in the Levee Seismic Vulnerability Assessment Methodology Report (URS, 2008). It is also based on subsequent recommendations from the ICB and seismic panel members (ICB, 2013; Balakrishnan and Perlea, 2013), respectively.

ULE seismic vulnerability assessments are based on empirical procedures developed for a screening-level evaluation. Future protocols, if necessary, for the design and implementation of any seismic remedial alternative should be based on more detailed site investigation, site characterization, and site-specific analytical procedures. Such additional studies should more precisely define the extent of mitigation required, and should reduce the scope and cost of mitigation. Additional site characterization and analyses may indicate remedial alternatives are not required.

6.1 Seismic Analysis Objective
The objectives of the seismic screening analyses are to:
 Evaluate, under existing conditions, the potential for liquefaction of the levee and/or the underlying foundation materials during a 200-year return period seismic event  Identify soft soils2 in the levee and/or the underlying foundation materials  Prepare longitudinal profiles of potentially liquefiable layers  Select levee segment boundaries for seismic vulnerability analysis  Identify and develop representative cross sections for seismic vulnerability assessments  Perform post-earthquake static and pseudo-static slope stability analyses  Evaluate seismically-induced deformation and resulting freeboard loss at the levee crown. Note that ULE analysts will make this assessment under existing conditions if no static remedial alternative(s) are needed, or will make the assessment with the selected static remedial alternative in place.
2 For ULE screening level seismic evaluation, soft soil is defined as a non-free-draining soil with estimated shear strength of less than 500 psf. This is not the same as “soft” soil defined for static stability analyses in Section 5.9.4
20150427_GuidanceDoc.docx 6-2 Issue Date: April 2015

SECTION 6.0 SEISMIC ANALYSIS
 Based on the amount of freeboard loss due to seismic deformation, categorize the relative seismic vulnerability of levee segments using a three-tiered system, as defined in Table 6-1. The three vulnerability classes are:
− Low vulnerability
− Medium vulnerability
− High vulnerability
 For frequently-loaded levees only, if a high vulnerability categorization is identified, then the additional efforts defined in Section 6.11 will be implemented.

6.2 WSE Conditions
ULE analysts should evaluate the seismic performance of levees along river systems using the higher of either the average summer or winter WSE when assessing liquefaction evaluation, seismic slope stability, and slope deformation. For levees along bypasses, or in other locations where water is not always present, the WSE should be set based on an evaluation of WSEs in adjacent segments, or groundwater levels. In the absence of such data, ULE analysts should use the WSE at either the waterside or landside levee toe elevation, based on engineering judgment.

For frequently-loaded levees, ULE analysts should use the WSE that is the mean high tide level on the waterside and the higher of either the winter or summer WSE on the landside.

Note that boring and CPT data used during liquefaction triggering analyses are corrected for groundwater depth at the time of exploration.

ULE analysts should consult with the Regional Technical Lead and ULE Task Order Manager when selecting WSEs along bypasses or at other locations where WSE information is not available.

6.3 Seismic Loading Conditions
ULE analysts should assess liquefaction and subsequent seismic vulnerability for one seismic loading condition: a 200-year return period seismic event. Figure 6-2 shows the peak horizontal acceleration (PHA) contours for ULE study areas under stiff soil conditions (i.e., shear wave velocity Vs,30 of 335 meter/second). The PHAs shown in Figure 6-2 correspond to 200year levels of peak horizontal acceleration that would occur on relatively stiff soils at depths typically on the order of 100 feet to 120 feet throughout ULE study areas (URS, 2012). Appendix K presents more background information and a discussion how Figure 6-2 was developed.

Amplification of these acceleration levels as they propagate upward through shallower foundation soils of lesser stiffness, and interactions of levee embankments with these motions, is addressed by representative analyses of two-dimensional dynamic response models that include both levees and foundation soils. The computer program QUAD4M was used to perform two-dimensional site response analyses. 20150427_GuidanceDoc.docx 6-3 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS

6.4 Criteria
ULE seismic vulnerability criteria for intermittently-loaded levees, summarized in Table 6-1, and frequently-loaded levees, summarized in Table 6-6, are based on a levee’s postseismic-event flood protection ability. Seismic vulnerability is estimated based on:
 The estimated amount of vertical deformation relative to landside levee height  Potential damage to internal structures (e.g., cutoff walls, etc.)  Potential for cracking of the levee embankment
 Remaining freeboard (10-year WSE +3 feet) after seismic deformation Table 6-1 Criteria for Seismic Vulnerability of Intermittently-Loaded Levees Amount of Crown2
Displacement Relative to
Landside Levee Height
(percent)
Potential for
Significant Damage to
Internal Structures
(e.g., Cutoff Walls)
Remaining Freeboard 2
for Post Seismic
Evaluation (10-Year
Flood WSE +3 feet) 3
Vulnerability
Class4 (PostSeismic Flood
Protection Ability)
< 10 No >0.3 m (1 foot) Low Vulnerability
<20 Possibly Between 0 and >0.3 m (1 foot) Medium Vulnerability ≥20
(Flow Slide Condition)
Yes None High Vulnerability
Note:
1 This table applies to intermittently-loaded levees. See Section 6.11 for information about frequently-loaded levees. 2 Vertical crown displacements can be estimated at 0.7 times the deviatoric deformation from simplified deformation analysis (such as Newmark type displacement), and by adding volumetric displacement as applicable. 3 Based on ULDC criteria for intermittently-loaded levees (Section 7.7.1 of ULDC [DWR, 2012]). 4 Analyses results must pass each of the criteria in the first three columns of the table at a given vulnerability class (the last column), or the corresponding segment should be rated at the next higher vulnerability class.

Although a segment’s seismic vulnerability class will be documented in each study area’s GER Volume 2, no seismic remedial alternative or associated cost will be established in the GER for what ULDC defines as intermittently-loaded levees. See Section 6.11 of this Guidance Document and Sections 7.6 and 7.7.2 of ULDC for seismic assessment of frequently-loaded levees.

6.5 Software

6.5.1 Liquefaction Potential
Two Microsoft Excel liquefaction-triggering analysis spreadsheets were developed for ULE.

The two spreadsheets are for SPT-based and CPT-based liquefaction triggering analyses, and correspond to the methodologies described in Section 6.7. Examples of the spreadsheets are in Appendix J.

When assessing liquefaction, ULE analysts should be aware that the CPT-based liquefaction spreadsheet may classify some fine-grained soils as liquefiable. In such cases, additional information regarding soil properties, including SPT blow counts within the same layer, Atterberg limits and moisture content test results (Section 6.7.1), are required to screen CPTbased liquefaction assessment results. This screening can be difficult and uncertain, as 1 20150427_GuidanceDoc.docx 6-4 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
such, ULE analysts should place more emphasis on SPT interpretations and material classification from laboratory test data. Therefore, SPT borings drilled under ULE should be selected as the primary source of data for liquefaction analyses. CPT and historical boring data should be considered a secondary data source, and should be used primarily to support evaluation of the longitudinal extents of liquefaction potential (Section 6.7.3).

Given the caveats described above, CPT data can be used to:
 Extrapolate the continuity of liquefiable strata based on engineering judgment and SPT liquefaction triggering analysis results at selected locations.  Identify zones as non-liquefiable that have high CPT tip resistance.  Perform liquefaction triggering analyses if no SPT data are available or if SPT data are limited.

6.5.2 Slope Stability Analyses
ULE analysts should perform seismic slope stability analyses using SLOPE/W (2007 and later versions), which is a two-dimensional limit equilibrium slope stability analysis software program developed by GEO-SLOPE International Ltd. (http://www.geoslope.com). ULE analysts should use the Spencer’s Method approach, which satisfies both moment equilibrium and force equilibrium, for all slope stability analyses. ULE analysts may consider using other slope stability analysis software, including UTEXAS4, upon approval of DWR’s Task Order Managers.

6.6 Analysis Approach
The overall methodology for seismic evaluation is based on the study presented in the Levee Seismic Vulnerability Assessment Methodology Report (URS, 2008). In essence, liquefaction triggering and seismic vulnerability assessment are based primarily on six types of data or information:
 200-Year PHA hazard map (Figure 6-2)
 Cyclic shear stress (Ƭmax) charts (Figure 6-3)
 Recommended Kmax vs. Input Motion PHA (Figure 6-4)
 Yield acceleration (Ky) estimation (Section 6.8.4)
 Recommended Newmark Displacement vs. Ky/Kmax relationship (Figure 6-5)  Seismic vulnerability classification (Table 6-1)
The following sections describe the procedures for using these six types of information to perform screening-level assessments of liquefaction and seismic vulnerability.

6.7 Liquefaction Triggering Analyses
Liquefaction triggering analyses evaluate whether or not the levee and/or the underlying foundation materials could be susceptible to liquefaction during a 200-year return period seismic event. In some cases, liquefaction triggering analyses results will also be used to estimate the post-seismic strengths of materials for use in seismic slope stability analysis. 20150427_GuidanceDoc.docx 6-5 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
ULE analysts should implement the following process to assess liquefaction potential (Figure 66).

6.7.1 Perform Liquefaction Potential Assessment
For the purpose of ULE, levee soils located at certain depths are not considered critical for seismic performance, and can be removed from liquefaction potential analysis. ULE analysts should use the following criteria to identify the depth of soils that are not located within the vertical liquefaction assessment zone for ULE:
 All unsaturated soils located above the analysis WSE defined in Section 6.2, and  All soils located below the greater of the following depths:
− 50 feet below the landside levee toe,
− Two times the levee height (measured at landside) below the landside levee toe, or − Bottom of the river channel.

If the soil layer susceptible to liquefaction continues below the bottom of the evaluation depth, the full depth of the liquefiable layer will be evaluated.

In the vertical liquefaction assessment zone, analysts can then screen out soils not susceptible to liquefaction based on the following criteria3 :
 All soils with (N1)60-cs ≥ 23 or qC,1mod ≥ 10 MPa or 100 tsf  All soils classified as CH or MH
 For intermittently-loaded levees, all soils classified as CL, as well as soils classified as ML with any of the following:
− Plasticity Index ≥ 10 (See Figure 6-7)
− Liquid Limit ≥ 35
− Water Content ≤ 0.8 x (Liquid Limit)4
 For frequently-loaded levees, soils classified as CL or ML with any of the following:
− Plasticity Index ≥ 10 (See Figure 6-7)
− Liquid Limit ≥ 35
− Water Content ≤ 0.8 x (Liquid Limit)4
 Compacted, fine-grained soils used for remedial alternatives described in each study area’s GER Volume 2
 Clayey sand (SC) with greater than 20 percent fines
3 See the list of Acronyms and Abbreviations in the Table of Contents for definitions of terms used here. 4 The water content for comparison with liquid limit should be the saturated water content. There is a potential for the water content of soil samples collected in the field to be lower than that at the time of a seismic event. Analysts should consider this during their assessment and apply engineering judgment as necessary.
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Atterberg limits and water content tests are very important in the evaluation of liquefaction susceptibility of fine-grained soils. Accurate field and laboratory classification of ML, CL and CL-ML soils can be very difficult and high quality Atterberg limit testing should be implemented to support, and as appropriate, override field classification in any design level seismic analyses.

In the absence of Atterberg limits test results for a fine-grained layer in this screening study, ULE analysts should use engineering judgment when considering fines contents and the nature of the fines. In general, soils field-classified as CL, CH, or MH can be considered unlikely to liquefy, but soils field-classified as ML or CL-ML should be considered potentially liquefiable, depending on the reported density.

If, based on the above criteria, the levee embankment and/or foundation materials are not considered susceptible to liquefaction and are not soft soils5 the materials may be classified as non-liquefiable, irrespective of earthquake loading. Soils not meeting the above criteria should be considered susceptible to liquefaction and should be assessed using the analyses discussed in Section 6.7.2.

The next step is to identify representative exploration locations and data for liquefaction triggering assessment. ULE analysts should review soil boring and CPT data and select an appropriate number of explorations for analysis to assess the liquefaction potential in the study area. For example, if the stratigraphy in a segment is generally uniform in terms of soil types and properties, one or two exploration locations may be sufficient for assessment.

Analysts should consider both toe and crown explorations.

ULE analysts should use the geologic plans and profiles for a GER study area to help select the number and location of explorations for analysis. Once ULE analysts have identified explorations for liquefaction triggering analysis, analysts should consult with the Regional Technical Lead and ULE Task Order Manager prior to performing analysis for the selected explorations.

6.7.2 Perform Liquefaction Potential Analyses
As noted, two Microsoft Excel liquefaction triggering spreadsheets (one SPT-based and one CPT-based) have been developed for use during ULE-wide evaluation of liquefaction potential and are based on the project-specific methodology developed for ULE. The SPTbased liquefaction spreadsheet was developed in accordance with the procedure recommended by Cetin et al. (2004). The CPT-based liquefaction spreadsheet was developed in accordance with the procedure recommended by Moss et al. (2006). The CPTbased correlations of Moss et al. (2006) are compatible with the SPT-based method Cetin et al. (2004). Examples of these spreadsheets are in Appendix J.

The spreadsheets calculate the factor of safety against liquefaction (FSL), which is equal to the ratio of the cyclic resistance ratio (CRR) to the cyclic stress ratio (CSR). Required parameters for input to calculate the cyclic stress ratio are:
5 For ULE screening level seismic analyses, soft soil is defined as a non-free-draining soil with estimated shear strength of less than 500 psf. This is not the same as “soft” soil defined for static stability analysis in Section 5.9.4.
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SECTION 6.0 SEISMIC ANALYSIS
 PHA
 Maximum shear stress (Ƭmax)
6 , which is embedded in the spreadsheet
 Effective overburden stress (σ′v) at the analyses WSE (i.e., the higher of either the winter or summer average)
 Location (crown, landside, or waterside)
Figure 6-2 shows the PHA contours for ULE study areas for a stiff soil condition (Vs,30=335 m/s).

The cyclic shear stress (Ƭmax) values, embedded in the ULE liquefaction triggering spreadsheets, are based on two-dimensional site response analyses developed for three general locations along a levee cross section: the waterside toe, the center of crown, and the landside toe. As documented in the Levee Seismic Vulnerability Assessment Methodology Report (URS, 2008), a range of ground motions for a stiff soil condition (Vs,30=335 m/s) was applied to the base of a two-dimensional cross section profile of representative levees and foundation soil conditions approximately 120 feet deep. The two-dimensional site response analyses calculated sitedependent amplification of the input motions based on the effects of the overlying stratigraphy and the topography of the levee embankments.

These two-dimensional site response analyses were performed with a WSE 10 feet below the crown elevation and with a straight line phreatic surface to the landside toe of the levee.

Considering these WSEs may be higher than the seismic analysis WSEs in many ULE study areas, ULE analysts should calculate CSR values using cyclic shear stress (Ƭmax) values from the two-dimensional site response analyses and site-specific effective overburden stress (σ′v) corresponding to the analysis WSE. The representative CSR values are calculated in the liquefaction triggering spreadsheet using the following equation:

CSR = 0.65 x Ƭmax / σ′v
Charts of cyclic shear stress values (Ƭmax) for each of the three locations are shown in Figure 6-3. These charts are also built into the SPT and CPT liquefaction evaluation spreadsheets to calculate cyclic stress values once the PHA and location are entered into the spreadsheets.

As shown in Figure 6-4, for borings or CPTs waterward of a point one-third up the waterside slope of the levee, ULE analysts should use waterside curves. For borings or CPTs located landward of a point one-third up the landside slope of the levee, ULE analysts should use the landside curves. For borings or CPTs one-third up the waterside and landside slopes, or on the levee’s crown, ULE analysts should use the curves for the levee crown.

Cyclic resistance ratio values (see Figure 6-8) are calculated based on corrected blow counts (N1)60 for SPT analyses (fines correction in the liquefaction triggering analysis is applied in the CRR equation and capped at 35 percent fines content as per Cetin et al., 2004) and on tip resistance (qc), sleeve friction (fs), and friction ratio (Rf) for CPT analyses.

Additional information used in the analyses includes USCS classifications, unit weights, 6 Ƭmax is defined for the ULE process as the peak cyclic shear stress and varies with location and depth, and, as noted, is embedded in the liquefaction triggering spreadsheets. 20150427_GuidanceDoc.docx 6-8 Issue Date: April 2015

SECTION 6.0 SEISMIC ANALYSIS
water contents, Atterberg limits data, groundwater depth at the time of the exploration, earthquake magnitude (MW), etc. In the absence of fines content data, ULE analysts should be aware that the SPT-based spreadsheet assumes fines contents based on USCS classifications and that entry of non-USCS classifications may result in erroneous liquefaction triggering calculations. Both spreadsheets provide the analyst with the option of assigning layers as non-liquefiable based on Atterberg limits data and/or soil type and the criteria outlined in Section 6.7.1. For the purpose of ULE, analysts should assume an Mw of

6.5 associated with the 200-year event. This magnitude was selected based on deaggregation of the earthquake sources considered in the probabilistic seismic hazard assessment (URS, 2012).

In some cases, groundwater data may not be available at the time the exploration was performed. For these cases, ULE analysts should use data from nearby explorations performed during a similar time of year or, when such data are unavailable, the average summer or winter WSE based on the date of the exploration.

In the absence of laboratory unit weight data (for use in the SPT-based spreadsheet), ULE analysts should determine unit weights based on soil types and N60 values as shown in Table 6-2.

Table 6-2 Unit Weights for Liquefaction Assessment
Soil Type N60 Unit Weight (pcf)
Clays and silts ≤ 4 115
5 to 8 120
≥ 9 125
Sands ≤ 10 115
11 to 29 125
≥ 30 130
Gravels All 130
Based on the spreadsheet analysis results, ULE analysts should use the following criteria to classify a soil layer, or vertical portion of a soil layer, as having liquefaction potential:
 If all FSL assessment values for a particular layer are equal to or greater than 1.25, the soil layer may be classified as non-liquefiable.
 If all FSL assessment values for a particular layer are equal to or less than 1.0, the soil layer may be classified as likely liquefiable.
 If the FSL assessment values are between 1.0 and 1.25, the soil layer may be classified as less likely liquefiable. If these less likely liquefiable layers are present in isolation in a non-liquefiable zone, the need for further evaluation will be assessed during the seismic vulnerability process.
 If the FSL assessment values for a particular layer are mixed and include multiple values less than 1.0, then the layer should be considered likely liquefiable, unless the layer can be logically split into sub-layers. ULE analysts should not perform this assessment in isolation; rather an assessment of the liquefaction profile should be performed to evaluate continuity of the layer.
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SECTION 6.0 SEISMIC ANALYSIS
As discussed in Section 6.5.1, when assessing liquefaction, ULE analysts should be aware that the CPT-based liquefaction spreadsheet may classify some fine-grained soils as liquefiable. In such cases, additional information regarding soil properties, including SPT blow counts within the same layer, Atterberg limits and moisture content test results (Section 6.7.1), are required to screen CPT-based liquefaction assessment results. This screening can be difficult and uncertain, and as such, more emphasis should be placed on SPT interpretations and material classification from laboratory test data. Therefore, SPT borings drilled under ULE should be selected as the primary source of data to be carried into the liquefaction triggering analyses. CPTs and historical borings should be considered a secondary data source and used primarily to support evaluation of the longitudinal extents of liquefaction potential (Section 6.7.3).

6.7.3 Evaluate and Document Longitudinal Extent of Potentially Liquefiable Layers
Use of reach boundaries established for static analysis (seepage, slope stability) are not always appropriate for seismic vulnerability assessment. Consequently, assessment of seismic vulnerability will use the term “segments.” ULE analysts will establish segments by reviewing liquefaction analysis results, topography and bathymetry, distance to river/channel, and existing and/or planned remedial alternatives. A segment may be a portion of a reach or may be composed of multiple reaches.

After analyzing the liquefaction potential of the selected explorations, ULE analysts should establish the longitudinal and lateral extents of likely and less likely liquefiable layers for the study area by evaluating the liquefaction analyses results for the selected explorations and the geologic plans and profiles. ULE analysts should make an assessment of the longitudinal extents of liquefiable layers based on the results of analyses described in Sections 6.7.1 and

6.7.2. Additionally, ULE analysts should consider any other relevant site information. The beginning and end points of likely and less likely liquefiable layers should extend to explorations determined to be non-liquefiable.

Liquefaction analysis results for the selected explorations can be used in multiple segments to establish the longitudinal extents of likely and less likely liquefiable layers. The longitudinal extents of liquefiable zones may extend into adjacent segments and/or affect only a portion of a segment.

6.8 Seismic Vulnerability Analyses

6.8.1 Overview
The purpose of the seismic vulnerability analysis is to estimate vertical deformation, which is then used to assign a seismic vulnerability class to a seismic segment (Table 6-1). The seismic segment(s) and analysis cross section(s) should be selected based on liquefaction analysis results, available topography and bathymetry, distance to river/channel, levee geometry, and existing and/or planned mitigation measures. The seismic vulnerability analysis sections representing levee segments with potential liquefaction may be selected independent of reaches evaluated for static conditions and could be representative of multiple reaches or segments.
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SECTION 6.0 SEISMIC ANALYSIS
Levee segments that have been identified to have potentially liquefiable soils and/or soft soils7 will be candidates for seismic vulnerability analysis. However, the seismic vulnerability analysis will only be performed using a statically-resistant levee configuration. A levee reach is considered statically-resistant if it satisfies one of the following criteria:
 The reach meets all static analyses criteria under existing conditions (i.e., no static remediation is required).
 The reach is remediated for static vulnerability based on GER Volume 1 results. Note that conceptual static remedial alternatives must be implemented if the reach does not meet all static analyses criteria. The selected static remedial alternative will be assumed to be in place for seismic vulnerability analyses.

For seismic vulnerability analyses, ULE analysts should evaluate both waterside and landside slopes with circular and wedge-shaped failure modes using the search routines available in the slope stability software. Potential deep and shallow failure surfaces should also be evaluated. For seismic deformation analyses (Section 6.8.4), the pseudo-static horizontal seismic coefficient K or Ky should be applied only in the horizontal direction.

After selecting the analysis sections for seismic vulnerability analyses, ULE analysts should implement the following steps (see Figure 6-1):
 Perform a post-seismic slope stability analysis (Section 6.8.3) using shear strengths as discussed in Section 6.8.2. The calculated factor of safety, denoted as FSPS, can then be used to assess whether the segment is unstable after the earthquake. If the FSPS is less than 1.0, then the levee segment is classified as having high vulnerability (see Table 6-1), and no seismic deformation analysis is required.  If FSPS is greater than 1.3, the section is classified as having low vulnerability, and no seismic deformation analysis is required.
 For seismic analysis cross sections not meeting the conditions stated above, seismic deformation analysis will be performed to identify the appropriate seismic vulnerability class.

6.8.2 Seismic Shear Strengths
Seismic loading is considered a rapid loading condition; for these ULE screening-level evaluations, shear strengths for post-seismic slope stability and seismic deformation analyses should be modeled as described below. Modeling of tension cracks is also discussed at the end of this section.

If statically remediated levee geometries are analyzed, strengths will be evaluated assuming full consolidation has occurred under the remediated geometry (i.e., conditions for an earthquake relatively soon after construction will not be evaluated). For final design, evaluation of end-of-construction conditions must be completed and consolidation time must 7 For ULE screening level seismic analyses, soft soil is defined as a non-free-draining soil with estimated shear strength of less than 500 psf. This is not the same as “soft” soil defined for static stability analyses in Section 5.9.4
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SECTION 6.0 SEISMIC ANALYSIS
be assessed to evaluate the likelihood of a seismic event occurring before primary consolidation is complete. This is particularly relevant to areas with thick clayey deposits.

6.8.2.1 Likely Liquefiable Soils with FSL ≤ 1
When saturated, loose coarse-grained and fine-grained materials are expected to contract and generate positive pore pressures during shear. During rapid seismic loading, the rate of pore pressure generation typically exceeds the rate of pore pressure dissipation, resulting in an incremental increase in pore pressures in these materials. This pore pressure increase leads to shear strength degradation that may ultimately lead to liquefaction or cyclic mobility.

Soils identified as likely liquefiable should be modeled using the post-liquefaction residual undrained shear strength. Residual undrained shear strengths should be estimated using the correlation proposed by Seed and Harder (1990), as shown on Figure 69. ULE analysts should use the strength at a point lying one third of the distance from the lower-bound curve to the upper-bound curve in Figure 6-9. To use Figure 6-9, residual undrained strength should be estimated based on (N1)60-cs-Sur values of the likely liquefiable layer(s). Plots of (N1)60-cs-Sur should be prepared for the seismic segments and median (N1)60-cs-Sur values should be used in the estimation of residual undrained strength.

Both the Cetin et. al. (2004) procedure for liquefaction triggering analysis and the Seed and Harder (1990) procedure for residual undrained strength estimation are empirical methods.

The fines correction for the (N1)60csSur values used in the Seed and Harder (1990) residual undrained strength correlation is not the same as the fines correction used in the liquefaction triggering analysis. As noted above, fines correction in the liquefaction triggering analysis is applied in the CRR equation as per Cetin et. al. (2004) and capped at 35 percent fines content. However, once a soil layer is considered as likely liquefiable, the fines correction is applied as per the Seed and Harder (1990) procedure. The (N1)60-cs-Sur values used in Figure 6-9 should be calculated based on the fines corrections (ΔNcorr) in Table 6-3 or Table 6-4 and the following equation:
(N1)60-cs-Sur = (N1)60 + ΔNcorr
Table 6-3 ΔNcorr Values Based on Fines Content.

Percent Fines ΔNcorr
0-5% 0
6-15% 1
16-30% 2
31-40% 3
41-60% 4
61-100% 5
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SECTION 6.0 SEISMIC ANALYSIS
Table 6-4 ΔNcorr Values Based on USCS Classification
USCS ΔNcorr
SP, SW, GP, GW 0
All Other Sands & Gravels 1
SC 2
ML 4
CL-ML 5
Note: Values based on suggested fines contents in USACE ETL 1110-2-580 (Draft), Table C-1.

To evaluate the residual undrained strength of coarse-grained and sand-like materials from CPT data, ULE analysts should convert CPT tip resistance to an equivalent (N1)60-cs-Sur value.

Based on a comparison between liquefaction triggering criteria from SPT data (Seed et al., 2003) and from CPT data (Moss et al., 2006), the following relationship has been developed for use in these screening evaluations:
(N1)60-cs-Sur ≈ qc,1,mod (tsf)/4.2
where the tip resistance has been corrected for increasing fines content and plasticity as:
qc,1,mod = qc,1 + Δqc
where qc,1 is the normalized tip resistance and Δqc is a “fines” correction factor as recommended in Moss et al. (2006). Δqc is a function of CSR and Rf and calculated in the ULE Excel spreadsheet using CPT data (Appendix J). The above correlation compares well with other relationships published in the literature (e.g., Robertson and Campanella, 1983; Kulhawy and Mayne, 1990).

6.8.2.2 Less Likely Liquefiable Soils with 1.0 < FSL < 1.25 As discussed in Section 6.7.2, ULE analysts should use engineering judgment to classify layers as likely liquefiable, less likely liquefiable, or non-liquefiable. This assessment should not be performed in isolation; rather, an assessment of the longitudinal geologic profile should be considered to evaluate continuity of the layer. Isolated blow counts resulting in 1.0 < FSL < 1.25 within a non-liquefiable layer may be considered non-liquefiable. However, if a liquefiable layer includes both FSL ≤ 1.0 and 1.0 < FSL < 1.25 zones, the layer should be identified as likely liquefiable, but may be divided into separate layers for post-liquefaction strength estimation and slope stability analysis.

For an FSL > 1, several procedures are generally used for estimating partial pore pressure generation using Tokimatsu and Yoshimi (1983) for sand and Evans (1987) and Hynes (1988) for gravel (Marcuson et al., 1989). Considering ULE’s screening-level evaluation process, ULE analysts should use a 30 percent reduction in the drained strength for soils with 1.0 < FSL < 1.25 (ICB, 2013; Balakrishnan and Perlea, 2013). 20150427_GuidanceDoc.docx 6-13 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS

6.8.2.3 Non-Liquefiable Cohesive Soils
Due to the transient seismic loading, non-liquefiable cohesive soils should be modeled using the undrained strengths. The generalized stress history and normalized soil engineering properties (SHANSEP) equation can be used to estimate the undrained shear strength from the estimated in situ effective stresses, σ′vo, and the maximum past pressure, σ′vm. su = S x(OCR)m x σ′vo
where
su is the undrained shear strength;
S is the normalized undrained shear strength ratio for normally consolidated soil; OCR is the overconsolidation ratio = σ′vm/ σ′vo;
σ′vo is the in situ vertical effective stress;
σ′vmis the maximum past pressure; and
m is an empirical constant that varies between 0.75 and 0.85 for most soils.

ULE analysts can use the special testing program results discussed in Section 5.0 to select appropriate values of the parameter S. In the absence of any site-specific data for finegrained soils, including ML and OH, a value of S of 0.25 is recommended (refer to Section 5.0 for soil group definitions). If vane shear strength data are available, these data should be evaluated during strength selection for seismic analyses.

Considering the relatively short durations of seismic shaking associated with 200-year return period seismic loading in the ULE study area, there will be no additional seismic modification factor applied to these static strengths to develop seismic strength parameters.

6.8.2.4 Non-Liquefiable Cohesionless Soils
Dense coarse-grained materials (i.e. non-liquefiable) are expected to dilate and potentially generate negative pore pressures during shear (when saturated). Due to the generation of negative pore pressures, the undrained shear strength of these materials could be higher than their drained strength, especially under rapid loading conditions. Because these materials are also permeable, it is prudent not to rely on negative pore pressures; rather, ULE analysts should use drained strengths to analyze these materials (see Section 5.0). The shear strength of these materials is generally represented by a friction angle and pre-seismic pore pressures. Typical dense coarse-grained material types include dense natural coarsegrained sediments and compacted fills composed of relatively clean gravels and sands.

Tension Cracks
Where tension cracks occur in the levee embankment, the soil strength along the failure surface above the depth of the cracks does not contribute to slope stability and negative normal stresses may develop at the interfaces between slices in the slope stability 20150427_GuidanceDoc.docx 6-14 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
calculations. The following crack depth guidance table is to be used in the ULE post-seismic slope stability assessment. These values were selected after discussion with the DWR seismic review panel. When the top 5 feet of the levee embankment is composed of granular fill, there is no need to consider a tension crack for slope stability analyses.

Material Crack Depth (feet)1
SP, SW, SM, SP-SM, SW-SM 0
ML, CL-ML, SC 3
CL 5
CH, MH 8
1 The maximum crack depth may not exceed ⅓ levee height (measured from the landside toe) In general, for the seismic slope stability analyses, tension cracks do not need to be modeled as filled with water. However, if conditions of water-filled tension cracks are present, ULE analysts should include these in analyses.

6.8.3 Post-Seismic Slope Stability Analyses
Using the seismic shear strengths discussed in Section 6.8.2, ULE analysts should complete post-seismic slope stability analyses using the search routines in the slope stability software.

No horizontal seismic coefficient is used in post-seismic analyses. See Figure 6-1 for key steps in the seismic vulnerability analysis process.

If the calculated FSPS for any critical shear surface is less than 1.0, then the segment is classified as having high vulnerability, and no further analysis is required. If the FSPS is greater than 1.3, the segment is classified as having low vulnerability, unless settlements due to volumetric strain (Section 6.9) result in a higher vulnerability class. If the FSPS is between 1.0 and 1.3, ULE analysts should perform seismic deformation analysis as described in Section 6.8.4. This FSPS range applies to the seismic environment and range of PHA values in ULE study areas and may not be appropriate for other geographic areas.

ULE analysts may copy and modify the slope stability files completed for the static analyses meeting all five static criteria (i.e., existing or remediated conditions, as appropriate) for seismic slope stability analyses. Modifications include changing the piezometric line and pore pressure information as discussed in Section 6.2, and changing the material shear strength as discussed in Section 6.8.2. If the WSE is above the landside toe, seepage analysis may need to be performed to calculate pore pressures for use in the slope stability analysis.

6.8.4 Seismic Deformation Analyses
Based upon the results of the post-seismic slope stability analyses for the seismic segments, if factors of safety are in the range of 1.0 to 1.3, then seismic deformation analyses will be implemented as described below.

The seismic deformation analysis presented in this document is based on the principles of Newmark-type deformation analysis (e.g., Makdisi and Seed, 1978; Seed, 1979; Idriss, 1985). The primary goal of the seismic deformation analysis is to estimate vertical deformations that are then used to assign a seismic vulnerability class (Table 6-1) for each 20150427_GuidanceDoc.docx 6-15 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
seismic segment. The results from seismic deformation analyses including vulnerability classes will be presented in each study area’s GER Volume 2 (Figure 1-16).

The Newmark-type deformation analysis is based on the rigid-block model with several simplifying assumptions including the assumption that displacements occur along a single, well-defined slip surface and accelerations and corresponding inertial forces act in the direction of initial movement at the center of gravity of the slide mass. Note that this type of deformation analysis may not yield highly accurate results for levees because of the simplifying assumptions. However, for a screening-level study, this approach is judged to be reasonable. A more sophisticated seismic deformation analysis is not warranted at this level of study and could be performed when the design of seismic improvements are undertaken.

As shown in Figure 6-1, the key steps in the Newark-type deformation analysis process are outlined below with a detailed discussion presented in the following text:
 Estimate the earthquake-induced accelerations acting on a slide mass. Typically, earthquake-induced accelerations on a slide mass are calculated using dynamic site response analysis. However, for ULE, a simplified approach is used to estimate the maximum average earthquake-induced acceleration on a slide mass (Kmax) as shown on Figure 6-4. The relationships of Figure 6-4 are based on two-dimensional, dynamic response analyses of representative levee and foundation conditions as described in the Levee Seismic Vulnerability Assessment Methodology Report (URS, 2008).  Perform pseudo-static slope stability analysis using a horizontal seismic coefficient, K, equal to one-half of Kmax. As discussed below, if the minimum FS is greater than 1.0, the section may be classified as having low vulnerability unless settlements due to volumetric strain (Section 6.9) result in a higher vulnerability class.  Identify and estimate potential sliding masses and associated seismic yield coefficients (referred to as yield acceleration, Ky). Ky represents the minimum horizontal acceleration required to produce a FS equal to 1.0. In the context of Newmark’s sliding-block analogy, Ky is interpreted as the minimum acceleration required to initiate downslope displacement of a slide mass. Ky is often calculated using the limit-equilibrium pseudostatic slope stability analysis.  Estimate the permanent deformation of a slide mass using Ky and Kmax as input parameters (Figure 6-5). This method assumes that permanent deformation initiates when the earthquake-induced accelerations acting on a slide mass exceed Ky on the slip surface. At this point, the slide mass begins to experience shear slippage relative to the underlying slope. Seismic loading is cyclic in nature, and the cyclic increase, decrease, and reversal of lateral loading generally produces periods of time during which relative slippage occurs. Multiple analyses have been performed using actual earthquake time histories, and with different ratios of Ky and Kmax, to develop average curves of resulting relative displacement as a function of Ky/Kmax and the duration of the number of loading cycles (URS, 2008). The curves shown in Figure 6-5 have been selected as suitable for screening-level predictions of resulting seismic deformations under ULE seismicity conditions. In other geological and seismic regions, different curves of this type would be needed.
20150427_GuidanceDoc.docx 6-16 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
Estimate Kmax Values for the Potential Shear Surfaces
Kmax is defined as seismic loading for a potential sliding mass as represented by the horizontal equivalent acceleration, which accounts for the cumulative effect of the nonuniform horizontal acceleration distribution in the overlying deformable material (Seed and Martin, 1966). Based on this concept, Kmax represents the maximum seismic coefficient for the sliding mass: Kmax = max (horizontal equivalent acceleration)/g.

Using the Kmax vs. PHA charts shown on Figure 6-4, estimate the Kmax values for shallow and deep shear surfaces based on the geometrical symmetry of the levee.  Symmetric or Softer Levee: levee sections where the landside and waterside toe elevations are about the same, and/or the foundation is generally softer (e.g., Holocene).

For these conditions, a softer seismic response might be expected; and, for the purposes of this screening-level study, the soft Kmax curve is selected from Figure 6-4.  Asymmetric or Stiffer Levee: levee sections where the difference between the elevation of the landside and waterside toe is greater than one levee height, measured from the higher of the landside toe and waterside toe of the levee, and/or the foundation is generally stiffer (e.g., Pleistocene). Then, a stiffer seismic response might be expected; and, for the purposes of this screening-level study, the stiff Kmax curve is selected from Figure 6-4.
 Intermediate Levee Symmetry/Stiffness: a levee section that falls between the symmetric and asymmetric definitions from above might be expected to show a mediumstiff seismic response; and, for the purposes of ULE’s screening-level study, the medium Kmax curve is selected from Figure 6-4.

Perform Pseudo-Static Slope Stability Analyses with A Single Seismic Coefficient Considering the seismic environment of ULE study areas, including PHA levels and an earthquake magnitude of 6.5, negligible Newmark displacements will result when the Ky/Kmax ratio is 0.5 or greater (see Figure 6-5). As a screening tool to limit the need for full Newmark displacement analysis, a pseudo-static slope stability analysis can be performed using a horizontal seismic coefficient, K, equal to one half of Kmax (K = 0.5Kmax). If the resulting calculated minimum FS for this acceleration level is equal to 1.0, then the K value is by definition the yield acceleration (Ky) and the Ky/Kmax ratio is equal to 0.5. The resulting Newmark displacement is approximately 0.16 feet as shown on Figure 6-5. If the minimum FS is greater than 1.0, the Ky/Kmax ratio will be greater than 0.5 and the corresponding Newmark displacement will be less than 0.16 feet. Consequently, if the minimum calculated FS for an acceleration of K = 0.5Kmax is equal to or greater than 1.0, then the analysis section may be considered low vulnerability (i.e. deformation will be less than 0.16 feet) unless settlement due to volumetric strain (Section 6.9) results in a higher vulnerability class.

ULE analysts should note that K should be applied only in the horizontal direction. In addition, circular and wedge-shaped failure surfaces should be checked on the waterside and landside at deep and shallow depths. Note that the Kmax value is different for deep versus shallow failure surfaces. As general guidance, shallow failure surfaces are those considered to penetrate a maximum of 2 to 3 feet below the levee toe (landside or waterside, depending on the analyzed slope). However, ULE analysts should exercise engineering judgment when selecting limiting depths for shallow surfaces. 20150427_GuidanceDoc.docx 6-17 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
Estimate the Yield Acceleration (Ky) Values
ULE analysts should only perform this step for study area sections that have a post-seismic FS between 1.0 and 1.3, and a pseudo-static FS with K=0.5Kmax that is less than or equal to 1.0.

ULE analysts should use the seismic shear strengths discussed earlier in Section 6.8.2.

Pseudo-static analyses should be completed using the search routines in the slope stability software to calculate the yield acceleration, Ky. Ky is defined as the minimum horizontal acceleration resulting in a just-stable condition equivalent to an FS of 1.0.

For each analysis section, pseudo-static slope stability analyses need to be completed for a range of horizontal seismic coefficients (e.g., K = 0.05g, 0.10g, 0.15g, etc., up to K = 0.5Kmax, as needed) to estimate the yield acceleration value. Circular and wedge-shaped failure surfaces should be checked on the waterside and landside at deep and shallow depths.

The Ky value for each potential failure mode (i.e., waterside and landside, deep and shallow, circular and wedge), should be selected as the K value that corresponds to an FS of 1.0.

Determine Vertical Newmark-Type Deformation
Based on the Kmax and Ky values determined above, vertical deformation is estimated as outlined below.

1. Estimate the minimum Ky/Kmax ratio value.

Calculate the Ky/Kmax ratios for each potential failure mode (i.e., waterside and landside, deep and shallow, circular and wedge) and select the minimum value of the Ky/Kmax ratio.

Note that the minimum Ky/Kmax ratio value is not necessarily given by the minimum Ky.

2. Estimate the Newmark-type displacements.

Using the minimum Ky/Kmax ratio estimated for each study section, calculate the Newmark-type displacements from the chart shown on Figure 6-5. Displacements are estimated for a moment magnitude, Mw = 6.5 event.

For ULE’s screening-level study, a 0.7 foot of vertical displacement for every 1.0 foot of Newmark displacement (along the failure plane) is recommended for estimating freeboard loss (vertical displacements).

6.9 Volumetric Settlement
Settlement associated with the mechanisms such as ground loss due to sand boil ejection and dissipation of excess pore pressure (i.e., post-liquefaction reconsolidation settlement) is known as volumetric strain. Volumetric settlements are added to the vertical settlement, as estimated from seismic deformation analysis, when thick, loose deposits are evaluated.

Deposits thicker than 20 feet of potentially liquefiable soil with (N1)60-cs less than 15 are considered for volumetric strain settlement. The volumetric strain should be calculated using the CSR value for the liquefiable layer, the (N1)60-cs value of the liquefiable layer, and the relationship recommended by Wu and Seed (2004) as presented in Seed et al. (2003). Cetin 20150427_GuidanceDoc.docx 6-18 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
et al. (2009) compares four commonly-used methods to evaluate volumetric settlement and actual field performance case histories. A summary of the four methods is shown in Table 65
Table 6-5 Mean Accuracy and Dispersion of Volumetric Settlement Methods Method Mean Accuracy1 Dispersion
Tokimatsu and Seed (1984) 1.45 R2=0.33
Ishihara and Yoshimine (1992) 0.90 R2=0.42
Shamato et al. (1998) 1.93 R2=0.36
Wu and Seed (2004) 0.98 R2=0.33
1 Ratio of average actual to average predicted settlement Based on the comparison, the overall dispersion (or variances/uncertainties) are not significantly different; R2 values of between 0.33 and 0.42 are all relatively poor. The mean accuracy indicates the value by which all predicted settlements must be multiplied to provide an overall net-zero balance against the field settlements observed. Tokimatsu and Seed (1984) and Shamato et. al. (1998) tend to underestimate actual observed settlements, and require scaling factors of 1.45 and 1.93, respectively, in order to zero out this bias. Ishihara and Yoshimine (1992) tend to slightly overestimate observed settlements, requiring a scaling factor of 0.90. Wu and Seed (2004) have negligible net bias represented by a net scaling factor of 0.98. Considering this negligible bias, Wu and Seed (2004) has been adopted for ULE seismic vulnerability evaluations.

Figure 610 shows the plot for estimating volumetric settlement.

6.10 Vulnerability Assessment
To establish the seismic vulnerability classification for a given segment, first freeboard loss is calculated by adding the Newmark-type vertical deformation and volumetric settlement as applicable8
. Freeboard loss is then evaluated as a percentage of levee height. The levee height is estimated from the hinge point on the landside toe. Finally, based upon the amount of deformation, a judgment is made concerning the potential for significant damage to internal structures in the levee (e.g., cutoff walls).

ULE analysts should assess the seismic vulnerability class of the evaluated levee segments using the seismic vulnerability classification system presented in Section 6.4 and Table 6-1.

ULE analysts should document the vulnerability class of the seismic segments on a levee alignment map in each study area’s GER Volume 2.
8 If the Newmark-type vertical deformation is already generating a high seismic vulnerability classification, there is no need to calculate volumetric settlement.
20150427_GuidanceDoc.docx 6-19 Issue Date: April 2015

SECTION 6.0 SEISMIC ANALYSIS

6.11 Seismic Vulnerability Assessment of Frequently-Loaded Levees (Urban-Non-Project Study Areas)

6.11.1 Criteria
ULE analysts should perform seismic vulnerability assessments for frequently-loaded levees in accordance with ULDC guidelines as they appear in Section 7.7.2 and Table 7-3. Based on the potential consequences, a higher ground motion level may be required for assessment and, in the absence of landside or waterside toe explorations, liquefaction analysis for crown explorations may need to be performed using landside or waterside CSR values, which are typically higher than the crown CSR values as demonstrated by Athanasopoulos-Zekkos and Seed (2013).

As noted in ULDC and shown in Table 6-6 below, for frequently-loaded levees with less than 5 feet of freeboard, the earthquake-induced deformations should be limited to less than 3 feet of overall (vertical and horizontal) deformation and about 1 foot of vertical displacement.

Seismic vulnerability analyses of frequently-loaded levees need to be performed as part of existing conditions analyses for each study area’s GER Volume 1. The levee alignment maps showing different vulnerability classes will be presented in the GER Volume 1 for frequently-loaded levees. A flow chart of the general protocol for assessment of frequentlyloaded levees is presented in Figure 6-11.

The seismic vulnerability assessment for frequently-loaded levees requires a robust analysis approach considering the consequences of levee failure. ULE analysts should apply the analysis approach presented in this Guidance Document using sound engineering judgment for such levees. If the estimated deformation of a given levee segment is close to the acceptable values, a more sophisticated seismic deformation analysis may be required to judge the need for seismic remedial alternatives.

Table 6-6 Criteria for Seismic Vulnerability of Frequently-Loaded Levees Amount of Total
Displacement
Amount of Vertical2
Displacement
Potential for Significant
Damage to Internal
Structures
Seismic Vulnerability
< 3 feet < 1 foot No Meets Criteria
≥ 3 feet ≥ 1 foot Yes Does Not Meet Criteria
1 This table presents criteria for frequently-loaded levees with less than 5 feet of freeboard. For larger cross sections and freeboard, larger deformation may be allowed based on engineering analysis and judgment (see ULDC Section 7.7.2 [DWR, 2012]). 2 Vertical displacement can be estimated as 0.7 times the total deformation from simplified deformation analysis (such as Newmark type displacement), and by adding volumetric settlement as applicable.

6.11.2 Seismic Remediation
If frequently-loaded levee segments do not meet seismic vulnerability criteria, the remediation protocols identified in the Conceptual Seismic Levee Remediation Alternatives and Cost Estimating Templates (URS, 2014) should be followed and verified by assessing 1 20150427_GuidanceDoc.docx 6-20 Issue Date: April 2015 SECTION 6.0 SEISMIC ANALYSIS
the post-seismic displacement criteria identified in Table 6-6. Upon verification, conceptual cost estimates following the guidance of Section 8 should be prepared.

6.12 References for Seismic Analysis
Athanasopoulos-Zekkos, A., Seed, R. 2013. “Simplified methodology for consideration of two-dimensional dynamic response of levees in liquefaction-triggering evaluation.” Journal of Geotechnical and Geoenvironmental Engineering, 139 (11).

Balakrishnan, A., Perlea, V. 2013. “Seismic Review Panel Report,” Seismic Review Panel Meeting on December 13, 2013. Prepared for DWR.

Beikae, M., Idriss, I., Hudson, M. 2003. User’s Manual for QUAD4M, A Computer Program to Evaluate the Seismic Response of Soil Structures Using Finite Element Procedures and Incorporating a Compliant Base. Center for Geotechnical Modeling, University of California, Davis, CA.

Boulanger, R., Idriss, I. 2004. Evaluating the potential for liquefaction or cyclic failure of silts and clays. Report UCD/CGM-04/01. Center for Geotechnical Modeling, University of California, Davis, CA.

Boulanger, R., Idriss, I. 2007. “Evaluation of Cyclic Softening in Silts and Clays,” Journal of Geotechnical and Geoenvironmental Engineering, American Society of Civil Engineers.

Bray, J., Sancio, R. 2006. “Assessment of the Liquefaction Susceptibility of Fine-Grained Soils,” Journal of Geotechnical and Geoenvironmental Engineering, American Society of Civil Engineers.

Cetin, K., Seed, R., Der Kiureghian, A., et al. 2004. “Standard penetration test-based probabilistic and deterministic assessment of seismic soil liquefaction potential.” Journal of Geotechnical and Geoenvironmental Engineering, 130 (12).

Cetin, K., Tolga Bilge, H., Wu, J., et al. 2009. “Probabilistic Model for the Assessment of Cyclically Induced Reconsolidation (Volumetric) Settlements.” Journal of Geotechnical and Geoenvironmental Engineering. Volume 135.

Department of Water Resources. 2012. Urban Levee Design Criteria. May.

Evans, M. 1987. “Undrained Cyclic Triaxial Testing of Gravels – The Effects of Membrane Compliance,” Ph.D. dissertation, University of California, Berkeley. California.

GEO-SLOPE International Ltd. 2007. Stability Modeling with SLOPE/W 2007: An Engineering Methodology. Fourth Edition.

Hynes, M. 1988. “Pore Pressure Generation Characteristics of Gravels under Undrained Cyclic Loading,” Thesis. University of California, Berkeley.

Idriss, I. 1985. “Evaluating seismic risk in engineering practice,” Proceedings of the 11th International Conference on Soil Mechanics and Foundation Engineering, San Francisco, California and Balkema, Rotterdam.
20150427_GuidanceDoc.docx 6-21 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
Independent Consultant Board. 2013. “Independent Consultant Board Report,” Seismic Meeting of December 13, 2013. Prepared for DWR.

Ishihara, K., Yoshimine, M. 1992. “Evaluation of settlements in sand deposits following liquefaction during earthquakes.” Soils and Foundations, 32(1).

Kulhawy, F., Mayne, P. 1990. Manual On Estimating Soil Properties for Foundation Design.

Report EL-6800. Electric Power Research Institute.

Makdisi, F., Seed, H. 1978. “Simplified procedure for estimating dam and embankment earthquake-induced deformations.” Journal of Geotechnical Engineering Division, ASCE, 104 (GT7).

Marcuson, W., Hynes, H., Franklin, A. 1990. “Evaluation and use of Residual Strength in Seismic Safety Analysis of Embankments”. Earthquake Spectra, Volume 6 (3).

Moss, R. Seed, R. Kayen, R. et al. 2006. “CPT-Based Probabilistic and Deterministic Assessment of In Situ Seismic Soil Liquefaction Potential.” Journal of Geotechnical and Geoenvironmental Engineering, Volume 132, Number 8. August. Errata to Equation (5) are published in the Journal of Geotechnical and Geoenvironmental Engineering, ASCE.

Robertson, P., Campanella, R. 1983. “Interpretation of cone penetration tests.” Canadian Geotechnical Journal. 20 (4), 718-745.

Seed R., Harder, L. 1990. “SPT-Based Analysis of Cyclic Pore Pressure Generation and Undrained Residual Strength.” Proceedings of H.B. Seed Memorial Symposium, Volume 2. BiTech Publishing, Vancouver.

Seed, H. 1979. “Considerations in the earthquake-resistant design of earth and rockfill dams.” Geotechnique. 29 (3).

Seed, H., Martin, G. 1966. “The Seismic Coefficient in Earth Dam Design,” ASCE Journal of Soil Mechanics. Volume 92.

Seed, R, Cetin, K., Moss, R., et al. 2003. “Recent Advances in Soil Liquefaction Engineering:

A Unified and Consistent Framework,” Keynote Address, Proceedings, 26th Annual Geotechnical Spring Seminar. Los Angeles Section of the GeoInstitute, American Society of Civil Engineers.

Shamoto, Y., Zhang, J., Tokimatsu, K. 1998. “Methods for evaluating residual post liquefaction ground settlement and horizontal displacement.” Soils and Foundations. 2 (2).

Southern California Earthquake Center. 1999. Recommended Procedures for Implementation of DMG Special Publication 117 Guidelines for Analyzing and Mitigating Liquefaction in California. March.

Tokimatsu, K., Seed, H. 1984. “Simplified Procedures of the Evaluation of Settlements in Clean Sands.” Report Number UCB/GT-84/16, University of California, Berkeley. 20150427_GuidanceDoc.docx 6-22 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
Tokimatsu, K., Yoshimi, Y., 1983, “Empirical Correlation of Soil Liquefaction Based on SPT NValue and Fines Content,” Japanese Society of Soil Mechanics and Foundation Engineering, Soils and Foundations, Volume 15 (4).

USACE. 2003. Engineering and Design – Slope Stability. EM 1110-2-1902.

URS Corporation. 2007. Probabilistic Seismic Hazard Assessment performed for the Delta Risk Management Study Phase 1 Project. Prepared for DWR.

URS Corporation. 2008. Levee Seismic Vulnerability Assessment Methodology Technical Memorandum. Prepared for DWR.

URS Corporation. 2012. Development of a 200-year Return Period Seismic Hazard Map for the Urban Levee Evaluations Program Region. Prepared for DWR.

URS Corporation. 2014. Conceptual Seismic Levee Remediation Alternatives and Cost Estimating Templates. Prepared for DWR.

Wright, S. 1999. “A Computer Project for Slope Stability Calculations.” Technical Manuals for UTEXAS4, May 1999, Revised September 1999, Shinoak Software, Austin, Texas.

Wu, J., Seed, R. 2004. “Estimating of liquefaction-induced ground settlement (case studies)”.

Proceedings of the 5th International Conference on Case Histories in Geotechnical Engineering. Paper 3.09. New York.
20150427_GuidanceDoc.docx 6-23 Issue Date: April 2015
SECTION 6.0 SEISMIC ANALYSIS
20150427_GuidanceDoc.docx 6-24 Issue Date: April 2015

FIGURES

FIGURES
Section 6
Figure 6-1 Seismic Vulnerability Analysis – Key Steps (Intermittently Loaded Levees)
Figure 6-2 Seismic Hazard Map
Figure 6-3 Recommended τmax versus Depth
Figure 6-4 Recommended Kmax vs. Input Motion PHA
Figure 6-5 Recommended Newmark Displacement vs. Ky/Kmax Figure 6-6 GER Liquefaction Assessment Flow Chart
Figure 6-7 Summary Guidance for Evaluating Fine-Grained Soils Liquefaction Susceptibility
Figure 6-8 Cyclic Resistance Ratio, equation by Cetin et. al., 2004.

Figure 6-9 Seed-Harder Plot for Residual Strength
Figure 6-10 Volumetric Strain
Figure 6-11 Seismic Vulnerability Analysis – Key Steps (Frequently Loaded Levees)

Figure
6-1
Seismic Vulnerability Analysis – Key Steps

Classify as “High Vulnerability”
Yes
No
Classify as “Low Vulnerability” unless
Volumetric Strain (Step 3f ) results in a
higher vulnerability class
Is
FSPS > 1.3?
Is
FS ≥1?
Step 4: If Warranted, Perform More Advanced Seismic Deformation Analysis (See Section 6.11) Step 3: Perform Simplified Seismic Deformation Analysis Evaluate and document longitudinal extent of liquefiable soils Select seismic levee segments and engineering cross-sections for seismic stability and deformation analyses
Step 1: Select Seismic Segments and Cross Sections for Seismic Vulnerability Analyses SEISMIC VULNERABILITY – KEY STEPS (INTERMITTENTLY-LOADED LEVEES) G:\DWR-7418\Project Files\TASK AREAS\General\GeotechAnalysis\GuidanceDocument\Final\Figures\Fig 6-1 Seismic Vulnerability.indd "
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All of the area north of the 0.11 g
contour should be considered
at the same PHA level of 0.11 g

0.11 0.11

0.13 0.2

0.15 0.3

0.25 0.35

0.4 0.4

0.3 5
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Yuba
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Marysville
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Walnut Creek
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121.5° W
122° W
122° W

39.5° N 39.5° N
39° N 39° N

38.5° N 38.5° N
38° N 38° N
0 5 10 15 20 2.5
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0 9 18 27 36 4.5
Kilometers
¯
PHA HAZARD FOR A 200-YEAR RETURN PERIOD
AND STIFF SOIL BASE CONDITION (VS30 335 M/SEC) FOR

MARYSVILLE, SACRAMENTO, AND

STOCKTON REGIONS
L:\Projects\DWR\GEOTECHNICAL\Urban\GuidanceDoc\ArcMap\GDOCD1F1PGAHAZ200_1.mxd TNC 08.06.2014 SAC Service Layer Credits: Sources: Esri, GEBCO, NOAA,
National Geographic, DeLorme, NAVTEQ, Geonames.org,
and other contributors

URBAN LEVEE EVALUATIONS
Department of Water Resources
Division of Flood Management
Figure
6-2
Seismic Hazard Map
PHA (g) Contour Line
ULE Study Area
Mapped fault used in
the hazard analysis
Concealed fault or
source zone used in
the hazard analysis
NOTES:

AMPLIFICATION OF THE PHAs

MAY BE REQUIRED BASED
ON SITE-SPECIFIC VS,30.

Recommended τmax versus Depth Figure
6-3
Department of Water Resources
Division of Flood Management URBAN LEVEE EVALUATIONS
PHI)
(1) Select PHI from Figure 6-1
Recommended Kmax vs Input Motion PHA Figure
6-4
Department of Water Resources
Division of Flood Management

URBAN LEVEE EVALUATIONS
Levee
Shape
Resulting
Response
Symmetric “Softer”
Less
Symmetric “Medium”
Asymmetric “Stiffer”

0.5 Recommended Newmark Displacement
vs Ky/Kmax Figure
6-5
Department of Water Resources
Division of Flood Management

URBAN LEVEE EVALUATIONS
100
.
.
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.
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.
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.
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.

0.01 0 0.2 0.4 0.6 0.8 1
Ky/Kmax
Newmark Displacement (ft)
MW = 6
MW = 6.5
MW = 7
GER Liquefaction Assessment Flow Chart Figure
6-6
Department of Water Resources
Division of Flood Management

URBAN LEVEE EVALUATIONS
Select appropriate number and location of
representative explorations to perform
liquefaction spreadsheet analyses.

SELECT

REPRESENTATIVE EXPLORATIONS

DEFINE EXTENTS OF

LIQUEFIABLE LAYERS
Define extents of likely and less likely liquefiable layers identified during the liquefaction spreadsheet analysis by extrapolation based on the geologic profile and
stratigraphy (Section 6.7.3).

PERFORM

LIQUEFACTION ASSESSMENT
Perform liquefaction spreadsheet analyses
on selected explorations to identify likely and less
likely liquefiable layers. (Section 6.7.2)
Document liquefaction results in the following:
 Liquefaction analysis spreadsheets
 Longitudinal geologic profile
Use ULE Program guidelines to establish
the zone of soils to be assessed. (Section 6.7.1)

ESTABLISH LIQUEFACTION

ASSESSMENT ZONE
Use ULE Program guidelines to identify soils
in assessment zone that are not susceptible
to liquefaction. (Section 6.7.1)

SCREEN OUT SOILS THAT

ARE NOT LIQUEFIABLE

DOCUMENT RESULTS
Summary Guidance for Evaluating
Fine-Grained Soils Liquefaction Susceptibility Figure
6-7 URBAN LEVEE EVALUATIONS
Clay-like: Non-susceptible to liquefaction
Sand-like: Susceptible to liquefaction
605040302010
74 0 10 20 30 40 50 60 70 80 90 100
PI < 10 CL-ML
LL (Liquid Limit)
PI (Plasticity Index) CL CH
U-Line
MH
ML
Note: See Section 6.7.1 for further clarification of liquefaction susceptibility.

Department of Water Resources Division of Flood Management Cyclic Resistance Ratio, equation by Cetin et al., 2004 Figure 6-8
Department of Water Resources Division of Flood Management

URBAN LEVEE EVALUATIONS
Seed-Harder Plot for Residual Strength Figure
6-9 URBAN LEVEE EVALUATIONS
50 For the ULE Program

1. Use the lower 1/3 line for
Sur selection

2. At or below (N1)60-cs = 4,
use Sur = 50 psf
50 Equivalent Clean Sand Blowcount, (N1)60-cs-Sur
Department of Water Resources
Division of Flood Management
Volumetric Strain Figure
6-10 URBAN LEVEE EVALUATIONS
SOURCE:

RECENT ADVANCES IN SOIL LIQUEFACTION ENGINEERING: A UNIFIED AND CONSISTENT FRAMEWORK By R.B. Seed, L.O. Cetin, R.E.S. Moss, A.M. Kammerer, J.Wu, J.M. Pestana, M.F. Fiemer, R.B. Sancio, J.D. Bray, R.E. Kayen, and A. Faris (26th Annual ASCE Los Angeles Geotechnical Spring Seminar, Keynote Presentation H.M.S. Queen Mary, Long Beach, CA April 30, 2003)
Department of Water Resources
Division of Flood Management
Does total
seismic
deformation meet
criteria?
Figure
6-11
Seismic Vulnerability Analysis – Key Steps

URBAN LEVEE EVALUATIONS
Department of Water Resources
Division of Flood Management
Step 2: Perform Post-Seismic Stability Analysis
Step 3a: Compute Kmax using Figure 6-4
Step 3e: Estimate vertical deformation as 0.7 times total Newmark displacement
Step 3c: Compute Ky value for sliding mass
Step 3d: Compute Newmark displacement using Kmax, Ky, and Figure 6-5 Yes
Step 3b: Perform pseudo-static stability analysis using K=0.5 Kmax No
Classify as Meets Criteria unless
volumetric strain (Step 3f ) results in a
higher vulnerability class
Is
FSPS < 1?
Yes
No
Perform post-seismic stability analysis
Continue to Step 3
No further analysis is needed.

Classify as Does Not Meet Criteria
Yes
No
Classify as Meets Criteria unless
Volumetric Strain (Step 3f ) results in a
higher vulnerability class
Is
FSPS > 1.3?
Is
FS ≥1?
Step 4: If Warranted, Perform More Advanced Seismic Deformation Analysis (See Section 6.11) Step 3: Perform Simplified Seismic Deformation Analysis Evaluate and document longitudinal extent of liquefiable soils Select seismic levee segments and engineering cross-sections for seismic stability and deformation analyses
Step 1: Select Seismic Segments and Cross Sections for Seismic Vulnerability Analyses SEISMIC VULNERABILITY – KEY STEPS (FREQUENTLY-LOADED LEVEES) Proceed to Seismic
Remediation Analysis
Document Results Yes
No
Step 3f: Calculate volumetric strain, if necessary
G:\DWR-7418\Project Files\TASK AREAS\General\GeotechAnalysis\GuidanceDocument\Final\Figures\Fig 6-11 Seismic Vulnerability.indd

APPENDIX J

APPENDIX J
Liquefaction Triggering Spreadsheets

REFERENCES:

1. 2.

3. 4.

5. 6.

NOTES & INSTRUCTIONS:

3. Color Code for Analysis Data Entry Color Code for Tabs

14. Factor of safety against liquefaction (FSL) is capped at 5.0

15. CPT data should not be entered for depths of 0.5 feet and shallower.

CONTRIBUTORS:

DWR URBAN LEVEE GEOTECHNICAL EVALUATIONS PROGRAM (ULE)

CPT BASED LIQUEFACTION ANALYSIS FOR ULE
Moss, R.E.S., Seed, R.B., Kayen, R.E., Stewart, J.P., Der Kiureghian, A. and Cetin, K.O., 2006. "CPT-Based Probabilistic and Deterministic Assessment of In Situ Seismic Soil Liquefaction Potential". Journal of Geotechnical and Geoenvironmental Engineering, Vol. 132, No. 8, August 2006, pp. 1032-1051, (doi 10.1061/(ASCE)1090-0241(2006)132:8(1032)). Errata to Equation (5) are published in the Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Sep 2007. Page 1177.

Lunne, T., Robertson, P. K. and Powell, J.J.M., 1997. Cone Penetration Testing in Geotechnical Practice. Blackie Academic & Professional. London.

13. In the normal distribution function for CRR, a Probability (PL) value of 15% was used in accordance with Reference 4

11. τmax options are "Crest", "Waterside", or "Landside" to obtain τmax values from the tabs Crest_Tau, Landside_Tau, and Waterside_Tau. The τmax values are given at 0.5 ft. intervals. The maximum depth for crest τmax = 140 feet, Landside τmax = 120 feet, and Waterside τmax = 100 feet.

URS Corporation 2013. Guidance Document for Geotechnical Analysis, Urban Levee Geotechnical Evaluations Project, Version 14.

Michael Luebbers, GE

16. Liquefaction susceptibilty of fine-grained soils can be assessed based on laboratory data and the criteria in Reference 3 (PI <10, LL<35, and w > 0.8 LL are susceptible to liquefaction). For intermittently loaded levees, CL materials are not considered susceptible to liquefaction. For frequently loaded levees, the Atterberg Limits criteria above apply to CL materials. Analysts may manually enter whether fine-grained soil is susceptible to liquefaction in Column AZ ("Liquefaction Susceptibility Based on Soil Type") based on laboratory data or evaluation of chacteristics based on soil deposits, in the absence of laboratory data. Atterberg Limits data sould not be entered for coarse-grained soils.

Sacramento City CouncilOctober 21, 2025

Sacramento City Council
October 21, 2025