HomeMy WebLinkAbout25SSL038_SUNLIGHT PRIMO_FINAL_REV0_REPORT7/9/25
SOIL STRUCTURES ENGINEERING, LLC PAGE 1
DESIGN REPORT & CALCULATIONS
FOR
SUNLIGHT MOUNTAIN SKI AREA - PRIMO LOWER TERMINAL
GLENWOOD SPRINGS, CO
REV# 0
(SSE PROJECT # 25SSL038)
I HEREBY CERTIFY THAT THIS REPORT WAS PREPARED BY ME OR UNDER MY DIRECT SUPERVISION.
THE CALCULATIONS SUBMITTED MODEL WORST CASE CONDITIONS AND COVER ALL OF THE
PROPOSED RETAINING WALLS DETAILED WITHIN THE SHOP DRAWING SUBMITTAL ACCOMPANYING
THIS REPORT.
BENJAMIN T. DAISS, P.E.LICENSE NO. 60191
DATE:
SUBMITTED BY:
BENJAMIN T. DAISS, P.E.
July 9, 2025
7/9/25
SOIL STRUCTURES ENGINEERING, LLC
EARTH RETENTION ▪ FOUNDATIONS ▪ STEEL & CONCRETE STRUCTURES
SOIL STRUCTURES ENGINEERING, LLC
EARTH RETENTION ▪ FOUNDATIONS ▪ STEEL & CONCRETE STRUCTURES
Sunlight Mountain Ski Area - Primo Lower Terminal
25SSL038
July 9, 2025
Index
1.0 Project Scope .....................................................................................................................................................3
2.0 Design Methodology ..........................................................................................................................................3
3.0 Wall System .......................................................................................................................................................3
3.1 Modular Block Wall Units .........................................................................................................................3
3.2 Soil Reinforcement ...................................................................................................................................3
4.0 Soil Properties ....................................................................................................................................................3
5.0 Maximum Surcharge Loadings & Slope Conditions ...........................................................................................4
6.0 Hydraulic Conditions ..........................................................................................................................................4
6.1 Water Application .....................................................................................................................................4
6.2 Erosion Control & Prevention ...................................................................................................................4
7.0 Seismic Conditions .............................................................................................................................................4
8.0 Wind Conditions .................................................................................................................................................4
9.0 External Stability & Settlement ...........................................................................................................................4
10.0 Limitations of Report ........................................................................................................................................4
Appendix Item A: Design Ref erences ......................................................................................................................5
Appendix Item B: Final Calculations .........................................................................................................................5
SOIL STRUCTURES ENGINEERING, LLC PAGE 2
1.0 Project Scope
This project includes one site retaining wall located along the northeast side of the proposed ski lift with a
maximum height of 13.83-feet and horizontal length of 101.58-feet.
2.0 Design Methodology
The proposed wall has been designed in accordance with the NCMA (National Concrete Masonry Association)
design methodology. Refer to the NCMA Design Manual for Segmental Retaining Walls, 3rd edition for additional
design and construction requirements.
3.0 Wall System
3.1 Modular Block Wall Units
The wall has been designed using Redi-Rock 28", 41", and 60" units using the standard 5.2° wall batter. Refer
to the manufacturers information for additional details on the proposed retaining wall system and its material
properties.
3.2 Soil Reinforcement
The proposed wall is designed as a gravity wall and does not require the use of geogrid soil reinforcement.
4.0 Soil Properties
Site soils information was not provided at the time of design. The soil strengths shown were assumed and shall
be verified by the project geotechnical engineer. Soil Structures Engineering, LLC should be contacted if the
noted soil strengths are not met as a redesign may be required.
Zone Description ɸ c'Ƴ
Retained Soil 1 CDOT Class 1 34°0 psf 135 pcf
Foundation Soil 1 Lean Clay - CL 25°75 psf 125 pcf
Sunlight Mountain Ski Area - Primo Lower Terminal
25SSL038
July 9, 2025
SOIL STRUCTURES ENGINEERING, LLC PAGE 3
5.0 Maximum Surcharge Loadings & Slope Conditions
Below are the maximum surcharge and site slope conditions as evaluated within this design. The noted extremes
may not be present for the entire length of any given wall. Dead load surcharge loadings are applied in addition to
any equivalent geometric loadings applied within the design calculations. Refer to the contract civil plans for
locations of all anticipated surcharge locations and grade geometry.
6.0 Hydraulic Conditions
6.1 Water Application
The proposed wall(s) are not located within a water application and the ground water elevation is assumed
to be located sufficiently below bottom of wall as to not influence overall stability. The project geotechnical
engineer shall consider fluctuations in seasonal ground water elevations during the verification external
failure mechanisms.
6.2 Erosion Control & Prevention
The contractor shall ensure positive drainage is maintained both during and after construction. Erosion
prevention and protection shall be maintained above and below the retaining wall as designed by others.
All downspouts, swales, and drainage features shall be diverted away from the wall location.
7.0 Seismic Conditions
The calculated 1-second peak ground acceleration (SD1) is 0.14g. Given the relatively low PGA and standard
reduction in required factors of safety for seismic designs, static calculations govern the overall design. The
calculations submitted do not include seismic sections for clarity. Seismic calculations may be provided upon
request.
8.0 Wind & Snow Conditions
No additional surcharge due to wind is anticipated or included within this design of below grade structures. All
freestanding, above grade structures shall be designed or relocated to not influence the below grade retaining
wall within a 1H:1V zone of influence. Refer to ASCE 7-16 for additional information on surcharge applications.
Additional surcharges for snow are excluded unless specifically included in the defined surcharge loadings. Snow
shall not be stored or piled above the proposed retaining wall(s).
9.0 External Stability and Settlement
Global Stability has been evaluated by Soil Structures Engineering, LLC using soils noted in section 4.0 and shall
be verified by the project geotechnical engineer. Local Bearing Capacities and Settlement are not covered under
the scope of this design and shall be evaluated under the scope of the project geotechnical engineer. The
foundation soils at each wall location shall be capable of supporting the applied bearing capacities shown within
the shop drawings without failure or excessive settlement.
10.0 Limitations of Report
The design presented within this report is based on the information provided. Soil Structures Engineering, LLC
accepts no liability for verifying site geometry, soil parameters, or ensuring all information provided is up to date.
The contractor and/or owner's representative shall notify Soil Structures Engineering, LLC of any changes or
conflicts with the actual site geometry prior to construction. Verification of site soil conditions, bearing capacities,
anticipated settlement, and global stability shall be completed as directed within the construction plans and
project specifications.
Wall No.Live Load (psf)Dead Load (psf)Toe Slope Back Slope
1 350 500 2H:1V Flat
Sunlight Mountain Ski Area - Primo Lower Terminal
25SSL038
July 9, 2025
SOIL STRUCTURES ENGINEERING, LLC PAGE 4
Appendix Item A: Design References
Iron Mountain Engineering, Inc. plan set for: Primo Lower Terminal Grading, Project No.: 116.001, Last Dated:
06/14/2025
NCMA Design Manual for Segmental Retaining Walls, 3rd Edition
NCMA SRW Best Practices, 2nd Printing, 2017
ASCE 7-16 Minimum Design Loads and Associated Criteria
IBC-2021 International Building Code, 2021
Appendix Item B: Final Calculations
Calculations attached after this sheet
Sunlight Mountain Ski Area - Primo Lower Terminal
25SSL038
July 9, 2025
SOIL STRUCTURES ENGINEERING, LLC PAGE 5
REA Analysis
Project: 25SSL038 - Sunlight Primo
Location: Glenwood Springs, CO
Designer: CMF
Date: 7/1/2025
Section: Section 1
Design Method: NCMA_09_3rd_Ed
Design Unit: Redi-Rock: 28
SOIL PARAMETERS Φ coh γ
Select Soil: 34 deg 0 lbf/ft2 135 lbf/ft3
Retained Soil: 25 deg 0 lbf/ft2 125 lbf/ft3
Foundation Soil: 25 deg 75 lbf/ft2 125 lbf/ft3
Leveling Pad: 38 deg 0 lbf/ft2 110 lbf/ft3
Crushed Stone Lvlng Pad
GEOMETRY
Design Height: 11.99 ft Live Load: 350.00 lbf/ft2
Wall Batter/Tilt: 5.20/ 0.00 deg Live Load Offset: 0.00 ft
Embedment: 1.00 ft* Live Load Width: 100.00 ft
Leveling Pad Depth: 1.00 ft
Slope Angle: 0.0 deg Dead Load: 0.0 lbf/ft2
Slope Length: 0.0 ft Dead Load Offset: 0.0 ft
Slope Toe Offset: 0.0 ft Dead Load Width: 0.00 ft
Leveling Pad Width: 6.00 ft D.L. Embedment: 0.00 ft
Vert δ on Single Dpth
Parapet Ht: 1.83
Parapet Depth: 2.00
Parapet Density: 145.00
Select Fill Offset: 1.00 ft
Select Fill Angle: 45.00 deg.
* Note: For all designs the passive resistance in front of the wall units is ignored for sliding calculations.
FACTORS OF SAFETY
Sliding: 1.50 Overturning: 1.50
Bearing: 2.00
REA Analysis 2024.3.122 1
RESULTS
FoS Sliding: 1.52 (lvlpd) FoS Overturning: 1.52
Bearing: 3167.15 FoS Bearing: 2.13
Name Elev.[dpth]ka Pa Paq PaT FSsl FoS OT %D/H
28 10.50[1.49]0.254 38 133 171 66.46 14.80 157%
28 9.00[2.99]0.219 132 230 362 31.46 4.95 78%
28 7.50[4.49]0.219 298 345 643 18.34 2.53 52%
41 6.00[5.99]0.304 736 637 1374 10.74 2.61 57%
41 4.50[7.49]0.285 1080 748 1828 8.28 1.95 46%
41 3.00[8.99]0.273 1490 860 2350 6.67 1.54 38%
60 1.50[10.49]0.335 2491 1231 3722 5.25 1.79 48%
60 0.00[11.99]0.319 3092 1337 4429 1.52 1.52 42%
Design Approach:
The design is a 'top down' approach. The values shown in the table[ka, kae, Pa, etc.] are the values from the
top of wall to the base of that row. For trial wedge analysis, the ka and kae are back-calculated from the Pa, Pae
values.
Column Descriptions:
ka: active earth pressure coefficient
Pa: active earth pressure
Paq: live surcharge earth pressure
Paq2: live load 2 surcharge earth pressure
Paqd: dead surcharge earth pressure
(PaC): reduction in load due to cohesion
PaT: sum of all earth pressures
FSsl(lvl Pad): factor of safety for sliding at each layer. (FS sliding below the leveling pad)
FSot: factor of safety of overturning about the toe.
REA Analysis 2024.3.122 2
REA Analysis 2024.3.122 3
COMPOUND RESULTS
Compound stability is a global analysis (Bishop) with the failure planes originating at the top of the slope / wall and
exiting out through the face of the wall. For MSE walls, the resistance of the geogrid reinforcement is included in the
analysis and the shear resistance of the face units is included.
ID Enter Point X Enter Point Y Exit Point X Exit Point Y Center X Center Y Radius FoS
2 20.39 11.99 5.00 0.00 -16.24 43.12 48.07 1.36
2 17.99 11.99 5.00 0.00 -14.66 34.33 39.56 1.36
2 22.79 11.99 5.00 0.00 -17.98 53.27 58.01 1.39
3 17.99 11.99 5.00 0.00 -1.07 19.61 20.53 1.43
3 20.39 11.99 5.00 0.00 -1.31 23.97 24.78 1.45
2 25.18 11.99 5.00 0.00 -19.84 64.80 69.39 1.47
3 15.59 11.99 5.00 0.00 -0.94 15.92 17.00 1.48
3 22.79 11.99 5.00 0.00 -1.62 29.01 29.76 1.48
2 27.58 11.99 5.00 0.00 -21.79 77.72 82.21 1.52
2 15.59 11.99 5.00 0.00 -13.31 26.85 32.49 1.55
3 25.18 11.99 5.00 0.00 -1.99 34.75 35.45 1.56
2 29.98 11.99 5.00 0.00 -23.82 92.06 96.47 1.60
4 20.39 11.99 5.00 0.00 3.87 17.32 17.36 1.63
2 13.19 11.99 5.00 0.00 -12.26 20.59 26.86 1.63
3 27.58 11.99 5.00 0.00 -2.40 41.20 41.86 1.63
3 13.19 11.99 5.00 0.00 -0.96 12.87 14.18 1.63
4 17.99 11.99 5.00 0.00 3.68 14.46 14.52 1.64
4 15.59 11.99 5.00 0.00 3.43 12.06 12.16 1.66
4 22.79 11.99 5.00 0.00 4.02 20.65 20.67 1.67
3 29.98 11.99 5.00 0.00 -2.84 48.35 48.99 1.71
GLOBAL RESULTS
Global stability is a global analysis (Bishop) with the failure planes originating at the top of the slope / wall and exiting
out below the wall in the area infront of the structure. For MSE walls, the resistance of the geogrid reinforcement is
included in the resisting forces. The curve may go through the base of the wall and the wall shear would be included.
In most cases the failure plane will pass below the structure.
ID Enter Point X Enter Point Y Exit Point X Exit Point Y Center X Center Y Radius Mo Mr FoS
3 15.59 11.99 -10.10 1.00 -0.48 14.04 16.20 187128.79 247580.68 1.32
2 15.59 11.99 -12.50 1.00 -2.18 16.01 18.22 217688.56 288204.77 1.32
3 17.99 11.99 -12.50 1.00 -1.46 18.17 20.41 255572.00 343060.53 1.33
2 13.19 11.99 -10.10 1.00 -1.17 12.25 14.37 153141.92 206165.44 1.34
3 13.19 11.99 -12.50 1.00 -2.15 12.33 15.35 172335.56 234841.74 1.35
3 15.59 11.99 -14.90 1.00 -3.07 15.99 19.09 238783.37 325104.69 1.35
2 15.59 11.99 -14.90 1.00 -3.86 18.17 20.41 242728.33 333005.48 1.37
2 17.99 11.99 -14.90 1.00 -3.14 20.52 22.79 291079.26 400412.98 1.37
2 17.99 11.99 -10.10 1.00 -0.70 18.37 19.75 233330.85 320937.42 1.37
3 20.39 11.99 -14.90 1.00 -2.41 23.05 25.34 341652.08 471859.57 1.37
REA Analysis 2024.3.122 4
REA Analysis
Project: 25SSL038 - Sunlight Primo
Location: Glenwood Springs, CO
Designer: BTD
Date: 7/9/2025
Section: Wall 1 Section 2
Design Method: NCMA_09_3rd_Ed
Design Unit: Redi-Rock: 28
SOIL PARAMETERS Φ coh γ
Select Soil: 34 deg 0 lbf/ft2 135 lbf/ft3
Retained Soil: 25 deg 0 lbf/ft2 125 lbf/ft3
Foundation Soil: 25 deg 75 lbf/ft2 125 lbf/ft3
Leveling Pad: 38 deg 0 lbf/ft2 110 lbf/ft3
Crushed Stone Lvlng Pad
GEOMETRY
Design Height: 7.50 ft Live Load: 100.00 lbf/ft2
Wall Batter/Tilt: 5.20/ 0.00 deg Live Load Offset: 0.00 ft
Embedment: 1.00 ft* Live Load Width: 3.00 ft
Leveling Pad Depth: 1.00 ft
Slope Angle: 0.0 deg Dead Load: 500.0 lbf/ft2
Slope Length: 0.0 ft Dead Load Offset: 3.0 ft
Slope Toe Offset: 0.0 ft Dead Load Width: 12.00 ft
Leveling Pad Width: 4.42 ft D.L. Embedment: 0.00 ft
Vert δ on Single Dpth
Parapet Ht: 1.50
Parapet Depth: 2.00
Parapet Density: 150.00
Select Fill Offset: 1.00 ft
Select Fill Angle: 45.00 deg.
* Note: For all designs the passive resistance in front of the wall units is ignored for sliding calculations.
FACTORS OF SAFETY
Sliding: 1.50 Overturning: 1.50
Bearing: 2.00
REA Analysis 2024.3.122 1
RESULTS
FoS Sliding: 1.79 (lvlpd) FoS Overturning: 1.91
Bearing: 1699.16 FoS Bearing: 3.93
Name Elev.[dpth]ka Pa Paq Paqd PaT FSsl FoS OT %D/H
28 6.00[1.50]0.254 39 38 0 77 >100 28.62 156%
28 4.50[3.00]0.155 94 45 106 245 46.11 6.21 78%
28 3.00[4.50]0.216 295 93 177 566 20.73 2.60 52%
41 1.50[6.00]0.297 721 109 378 1208 12.08 2.66 57%
41 0.00[7.50]0.280 1062 109 532 1703 1.79 1.91 46%
Design Approach:
The design is a 'top down' approach. The values shown in the table[ka, kae, Pa, etc.] are the values from the
top of wall to the base of that row. For trial wedge analysis, the ka and kae are back-calculated from the Pa, Pae
values.
Column Descriptions:
ka: active earth pressure coefficient
Pa: active earth pressure
Paq: live surcharge earth pressure
Paq2: live load 2 surcharge earth pressure
Paqd: dead surcharge earth pressure
(PaC): reduction in load due to cohesion
PaT: sum of all earth pressures
FSsl(lvl Pad): factor of safety for sliding at each layer. (FS sliding below the leveling pad)
FSot: factor of safety of overturning about the toe.
REA Analysis 2024.3.122 2
REA Analysis 2024.3.122 3
COMPOUND RESULTS
Compound stability is a global analysis (Bishop) with the failure planes originating at the top of the slope / wall and
exiting out through the face of the wall. For MSE walls, the resistance of the geogrid reinforcement is included in the
analysis and the shear resistance of the face units is included.
ID Enter Point X Enter Point Y Exit Point X Exit Point Y Center X Center Y Radius FoS
2 13.42 7.50 3.42 0.00 -3.00 18.98 20.03 1.35
2 11.92 7.50 3.42 0.00 -2.63 15.42 16.56 1.37
2 14.92 7.50 3.42 0.00 -3.43 23.07 24.06 1.40
2 16.42 7.50 3.42 0.00 -3.90 27.71 28.66 1.44
2 10.42 7.50 3.42 0.00 -2.34 12.39 13.66 1.47
2 17.92 7.50 3.42 0.00 -4.41 32.89 33.81 1.53
3 13.42 7.50 3.42 0.00 3.16 10.76 10.77 1.55
3 11.92 7.50 3.42 0.00 3.01 9.02 9.03 1.57
3 14.92 7.50 3.42 0.00 3.28 12.78 12.78 1.58
3 16.42 7.50 3.42 0.00 3.38 15.08 15.08 1.61
3 10.42 7.50 3.42 0.00 2.84 7.56 7.58 1.63
2 19.42 7.50 3.42 0.00 -4.94 38.64 39.53 1.69
3 17.92 7.50 3.42 0.00 3.47 17.66 17.66 1.69
2 8.92 7.50 3.42 0.00 -2.15 9.85 11.31 1.70
2 20.92 7.50 3.42 0.00 -5.49 44.94 45.81 1.83
3 19.42 7.50 3.42 0.00 3.56 20.52 20.52 1.90
2 7.42 7.50 3.42 0.00 -2.11 7.76 9.53 2.00
4 14.92 7.50 3.42 0.00 5.70 9.07 9.35 2.00
4 16.42 7.50 3.42 0.00 5.98 10.58 10.89 2.02
4 13.42 7.50 3.42 0.00 5.41 7.76 8.01 2.02
GLOBAL RESULTS
Global stability is a global analysis (Bishop) with the failure planes originating at the top of the slope / wall and exiting
out below the wall in the area infront of the structure. For MSE walls, the resistance of the geogrid reinforcement is
included in the resisting forces. The curve may go through the base of the wall and the wall shear would be included.
In most cases the failure plane will pass below the structure.
ID Enter Point X Enter Point Y Exit Point X Exit Point Y Center X Center Y Radius Mo Mr FoS
1 11.92 7.50 -7.41 1.00 -0.81 13.36 14.01 77821.43 112698.95 1.44
1 11.92 7.50 -5.91 1.00 0.03 12.40 12.86 68252.61 98917.58 1.44
2 11.92 7.50 -8.91 1.00 -1.30 13.22 14.40 86478.29 125460.12 1.44
1 11.92 7.50 -8.91 1.00 -1.63 14.28 15.15 88165.61 128004.53 1.44
2 13.42 7.50 -8.91 1.00 -0.83 14.83 16.02 103590.85 150691.90 1.45
2 11.92 7.50 -7.41 1.00 -0.26 11.73 12.89 74768.16 109372.11 1.46
3 11.92 7.50 -10.41 1.00 -1.56 12.18 14.26 92508.81 135522.92 1.46
2 11.92 7.50 -5.91 1.00 0.78 10.36 11.50 63872.78 93787.19 1.46
2 13.42 7.50 -7.41 1.00 0.20 13.22 14.40 91621.44 134841.99 1.46
1 13.42 7.50 -7.41 1.00 -0.59 15.75 16.26 97140.38 142987.44 1.47
REA Analysis 2024.3.122 4