design of the south doña ana dam
DESCRIPTION
Las Cruces is a small city located in Dona Anna county, southern New Mexico. Recently, this city is experiencing rapid population growth and infrastructural development. Physiographically, the city lies in Rio Grande valley and its eastern extension is bound by Organ mountain range. This will cause flood storm during the rainy season and pose risk to public safety and their property in a proposed area. Due to the age, lack of proper maintenance and recent significant downstream development, existing flood control dam in proposed may not be adequate. Therefore, in order to protect people and economic infrastructures, construction of a new flood control dam, named as South Dona Anna Dam, is proposed. This project is chosen for the fulfillment of requirement of CE 485 design project. The proposed dam is located in City of Las Cruces, Dona Ana County, New Mexico. The center of dam axis is located at lat 32023’28.25’’ and long 106047’55.34’’. Elevation of the area varies from 4000 ft in the southern part to 5833 ft in northern part and the annual rainfall is less than 9 inches. The catchments were found to be 185920000 square feet with 16 sub-basins/ reaches.TRANSCRIPT
Design of the South Doña Ana DamDesign of the South Doña Ana Dam
Project Members:Project Members:
Daneel NortierDaneel NortierDesh Raj SonyokDesh Raj Sonyok
Tran Tri DungTran Tri DungUmaima Al-AqtashUmaima Al-Aqtash
Civil Engineering DepartmentCivil Engineering DepartmentNew Mexico State UniversityNew Mexico State University
International Engineering Group (EIG)International Engineering Group (EIG)
What is GPRWhat is GPR??What is GPRWhat is GPR??ContentsContentsContentsContents
Background Background
Objectives Objectives
LocationLocation
Physiography and climatePhysiography and climate
MethodologyMethodology
Preliminary ResultsPreliminary Results
Discussion and ConclusionDiscussion and Conclusion
BackgroundBackgroundBackgroundBackground
Doña Ana county, southern New Mexico, 6.5mi North of Doña Ana county, southern New Mexico, 6.5mi North of Las CrucesLas Cruces
Originally installed in 1950’s (1600 ft)Originally installed in 1950’s (1600 ft)
The proposed South Doña Ana Dam for 100yr floodThe proposed South Doña Ana Dam for 100yr flood
Installation – almost unoccupiedInstallation – almost unoccupied
Readily developable (Flat): 60K (1960) – 175k (2000)Readily developable (Flat): 60K (1960) – 175k (2000)
7900Acres- (Private 54%,BLM 43%,State 4%)7900Acres- (Private 54%,BLM 43%,State 4%)
Unemployment: 6.4% (5.8%)Unemployment: 6.4% (5.8%)
Per Capita Income: $10,542 ($21,587)Per Capita Income: $10,542 ($21,587)
Below Poverty: 22.8% (12.4%)Below Poverty: 22.8% (12.4%)
ObjectivesObjectivesObjectivesObjectives
Propose 100 year return period structurePropose 100 year return period structure1)1) Elephant Butte Irrigation District (EBID)Elephant Butte Irrigation District (EBID)
2)2) Dona Ana County Office of the Flood Commissioner (DACFC)Dona Ana County Office of the Flood Commissioner (DACFC)
3)3) La Union Soil and Water Conservation Service (LUSWCD)La Union Soil and Water Conservation Service (LUSWCD)
4)4) USDA National Resource Conservation Service (NRCS)USDA National Resource Conservation Service (NRCS)
Effective DesignEffective Design1) Surface Hydrology1) Surface Hydrology
2) Storage and Drainage2) Storage and Drainage
3) Transmission3) Transmission
4) Stability and Settlement4) Stability and Settlement
Cost AnalysisCost Analysis $$$$$$$$
LocationLocationLocationLocation
City of Las Cruces, Dona Ana county, New MexicoCity of Las Cruces, Dona Ana county, New MexicoDam axis: lat. 32Dam axis: lat. 320023’28.25’’ and long. 10623’28.25’’ and long. 1060047’55.34’’ 47’55.34’’
Dam Axis
Highly populated
Physiography and ClimatePhysiography and ClimatePhysiography and ClimatePhysiography and Climate
TopographyTopography
Elevation: 4000 ft - 5833 ftElevation: 4000 ft - 5833 ft
Semi-desert climateSemi-desert climate
Rainfall: 9 inchRainfall: 9 inch
Snowfall: 3.2 inch annually Snowfall: 3.2 inch annually (peaks)(peaks)
MethodologyMethodologyMethodologyMethodology
Delineation of the Watershed Delineation of the Watershed
Use of AutoCAD 2007Use of AutoCAD 2007 Topographic maps from USGSTopographic maps from USGS
Soil CharacteristicsSoil Characteristics Soil survey of Dona Ana County area New Soil survey of Dona Ana County area New
Mexico (Bulloch and Neher, 1980)Mexico (Bulloch and Neher, 1980) Curve number of soils: Soil Conservation Curve number of soils: Soil Conservation
Service (SCS) methodService (SCS) method
Methodology Methodology …Continued…ContinuedMethodology Methodology …Continued…Continued
Hydrologic Analysis Hydrologic Analysis Determined 100 year rainfall from NOAA Determined 100 year rainfall from NOAA
database,(2007)database,(2007) UUsed HEC-HMS software to determine surface sed HEC-HMS software to determine surface
runoffrunoff Routing Analysis (Inflow-Outflow relationship)Routing Analysis (Inflow-Outflow relationship)
Maximum outflow and maximum storage Maximum outflow and maximum storage capacitycapacity
Design of trapezoidal channel for the outflowDesign of trapezoidal channel for the outflow
Hydraulic design: outlet pipe and trapezoidal channelHydraulic design: outlet pipe and trapezoidal channel Slope stability, settlement, and seepage analysisSlope stability, settlement, and seepage analysis Economic analysisEconomic analysis
Watershed CharacteristicsWatershed CharacteristicsWatershed CharacteristicsWatershed Characteristics
Total area: Total area:
17.27 km17.27 km22
1727.25 hectare1727.25 hectare
Stream gradients: Stream gradients:
0.018 – 0.1280.018 – 0.128
Watershed CharacteristicsWatershed CharacteristicsWatershed CharacteristicsWatershed Characteristics
16 sub-basins16 sub-basins
Soil Type and Curve NumberSoil Type and Curve NumberSoil Type and Curve NumberSoil Type and Curve Number
CN: 62 – 88CN: 62 – 88
)8.0(
)2.0( 2
SP
SPQ
+−=
101000 −=CN
S
HydrologyHydrologyHydrologyHydrology
HEC-HMS model of the watershedHEC-HMS model of the watershed
HydrologyHydrologyHydrologyHydrology
100 yrs flood: 3.6 100 yrs flood: 3.6 inin
HEC-HMS HEC-HMS Hydrograph:Hydrograph:
Peak flow: 918.36 cfs Peak flow: 918.36 cfs (after 13.5 hours)(after 13.5 hours)
HydraulicsHydraulicsHydraulicsHydraulics
Volume vs. Head Relationship : S=1.522*HVolume vs. Head Relationship : S=1.522*H2.0812.081
Max. Vol. without outflow: 376.79 acre-ft Max. Vol. without outflow: 376.79 acre-ft
Max. water depth without outflow: 14.5 ftMax. water depth without outflow: 14.5 ft
Inflow-outflow relationship:Inflow-outflow relationship:
Maximum storage: 263.98 acre-ftMaximum storage: 263.98 acre-ftMaximum outflow: 119.71cfs Maximum outflow: 119.71cfs Maximum head: 11.9 feet (after 23.5 hour)Maximum head: 11.9 feet (after 23.5 hour)
(I1+I2)/2 – (O1+O2)/2 = S2 – S1
Inflow-Outflow-StorageInflow-Outflow-StorageInflow-Outflow-StorageInflow-Outflow-Storage
Hydraulic DesignHydraulic DesignHydraulic DesignHydraulic Design
Concrete pipe length with square edge:Concrete pipe length with square edge:
Length = 140 ft Diameter = 3 ftLength = 140 ft Diameter = 3 ft
Trapezoidal concrete lined channel: Manning equationTrapezoidal concrete lined channel: Manning equation
B = 15 ft ; Minimal depth = 3.7 ft; B = 15 ft ; Minimal depth = 3.7 ft;
Side slope = 1V: 2H; Slope = .003Side slope = 1V: 2H; Slope = .003
For peak outflow:For peak outflow:
Froude number = 0.96 (subcritical condition)Froude number = 0.96 (subcritical condition)
Flow velocity = 5.58 ft/secFlow velocity = 5.58 ft/sec
V = k/n * (A/P)2/3 * S1/2
Height of embankment: Height of embankment:
Crest width: Crest width:
ftz
w 13105
=+=
boardfreewaterofdepthHeight +=
ftz 15=
ftw 15=
Cross-section A-A
Slope Stability AnalysisSlope Stability AnalysisSlope Stability AnalysisSlope Stability Analysis
Design of Embankment: Design of Embankment:
Slope Stability AnalysisSlope Stability AnalysisSlope Stability AnalysisSlope Stability Analysis
STABL computer program: STABL computer program:
2D limiting equilibrium methods2D limiting equilibrium methods
for the stability analysisfor the stability analysis
Bishop method:Bishop method:
Applicable to circular failure surfaceApplicable to circular failure surface
Janbu method Janbu method
A method of slices applicable to circular and noncircular A method of slices applicable to circular and noncircular failure surfacesfailure surfaces
Most critical surface and their corresponding Most critical surface and their corresponding factor of safetyfactor of safety
Design component
Soil type Wet unit wt (lb/ft3)
Sat. unit wt (lb/ft3)
Cohesive intercept (psf)
Friction angle (deg)
Foundation GC 116 135 1000 32
Core ML-Cl 110 120 700 20
Shell GM 108 127 800 33
Slope Stability AnalysisSlope Stability AnalysisSlope Stability AnalysisSlope Stability Analysis
Table: Seven cases of slope stability analysis
Table 2 Soil properties of dam
Case Description Operating condition
Safety Factor
I Wide core Normal 7.72
II Wide core Rapid drawdown 4.61
III Buttress 3:1 Rapid drawdown 4.49
IV Narrow core Rapid drawdown 4.88
V Buttress 3.5:1 Rapid drawdown 4.64
VI Buttress 4:1 Rapid drawdown 4.81
VII Downstream slope for case II Steady seepage 4.07
Slope Stability AnalysisSlope Stability AnalysisSlope Stability AnalysisSlope Stability Analysis
Case IV: Narrow core in rapid drawdown conditionCase IV: Narrow core in rapid drawdown condition
Crest width: 15 ftHeight: 15 ftWidth: 90 ft
Shell: Upstream slope: 3:1 Downstream slope: 2:1
Core: Upstream slope: 1: 1 Downstream slope: 1:1
Factor of safety = 4.88
Slope Stability AnalysisSlope Stability AnalysisSlope Stability AnalysisSlope Stability Analysis
Slope stability analysis of downstream slope for case IV:Slope stability analysis of downstream slope for case IV:
Factor of safety =4.069 with most critical failure surface from Janbu method
Slope Stability AnalysisSlope Stability AnalysisSlope Stability AnalysisSlope Stability Analysis
Details of the embankment design:Details of the embankment design:
Core:ML-CL Shell:
GCShell:GC
Seepage AnalysisSeepage AnalysisSeepage AnalysisSeepage Analysis
• Flow q=1.70 ft3/day/ft• Velocity = 2.43*10-6 ft/s
• Check for piping: i=.91 and icritical=1.04
i<icritical ; no piping will occur
Seepage AnalysisSeepage AnalysisSeepage AnalysisSeepage Analysis
Check for uplifting
umax = 916.56 lb/ft
Load (qb) due to the dam = 1113750 lb/ft
No uplift
Sources: J.W. Hawley, 1984Sources: J.W. Hawley, 1984 Sources: John Shomaker & Associates Inc.Sources: John Shomaker & Associates Inc.
Settlement: Geology and HydrogeologySettlement: Geology and HydrogeologySettlement: Geology and HydrogeologySettlement: Geology and Hydrogeology
Schmertmann method (1970): Schmertmann method (1970): - Define an average settlement (at the centerline) of dam under saturated / unsaturated soil condition
σ- settlement (mm)β - cone factor (3.5 for strip footing)qnet - net footing pressure in kPa (applied stress minus soil pressure above the base of footing)∆zi - thickness of the ith layer (m) (Ico)i –influence factor of the ith layerqc - cone resistance taken from quasi-static cone test data (Mpa)
SettlementSettlementSettlementSettlement
Timoshenko and Goodier method (1951):Timoshenko and Goodier method (1951):- Estimation of final elastic settlement at the center and corner of footing (with the sat/unsaturated soil in dam separately)- Can not consider saturation condition of the ground soil
Settlement time (consolidation): Settlement time (consolidation):
ρ - settlement (m)q - intensity of contact pressure in units of Es (MPa)B - least lateral dimension of footing in units of ρ (m)Iw – influence factor which depends on shape of footing and its rigidity Es, µ - elastic properties of soil
t - time (T)Tv - time factor Cv - coefficient of consolidation (L2/T)Hdr - drained length (L)
SettlementSettlementSettlementSettlement
SettlementSettlementSettlementSettlement
L/B > 10: Strip footing
Timoshenko-Goodier method: Inclination in the top of dam = 0.0002 mm
Consolidation time:Cv = 0.000101 cm2/secTime required for completion 93% of the maximum
settlement is to be 8927 years
MethodMethod UnsaturatedUnsaturated(mm)(mm)
SaturatedSaturated(mm)(mm)
Schmermann 32.2 39.9
Timoshenko-Goodier Center: 80.6 Center: 94.9
Corner: 41.8 Corner: 49.2
SettlementSettlementSettlementSettlement
Estimation of settlement:
Embankment MaterialsEmbankment MaterialsEmbankment MaterialsEmbankment Materials
Shell: GC ~ TE Core: CL-ML ~ Bj Soil found within 10 miles
Soil Group Permeability USCS
Bj Very slow CL, ML, SM, SC
TE Moderate GM, GP, GC
Cost AnalysisCost AnalysisCost AnalysisCost Analysis
Dam Construction: Cost Rate Amount Cost
Earthwork $9.00 per yd3 670 $6,030.00
Fill - Impervious Material $7.50 per ton 83000 $622,500.00
Fill - Gravelly Sand $7.50 per ton 73140 $548,550.00
Pre-Cast 36" Concrete Pipe $36.00 per foot 140 $5,040.00
Concrete In Place $160.00 per yd3 130.5 $20,880.00
Trash Rack (assuming Square) $15.00 per ft3 64 $960.00
Reinforcing Steel $562.00 per short ton 1.5 $843.00
Roller $600.00 per day 90 $54,000.00
Scraper $1,000.00 per day 90 $90,000.00
Machine operation $25.00 per hr 1440 $36,000.00
Human Labor $12.00 per hr 1 Year $345,600.00
Erosion Control $20.00 per linear foot 2000 $40,000.00
Overhead Costs $15,000.00 1 $15,000.00
Total $1,785,403.00
ConclusionsConclusionsConclusionsConclusions
Average CN ranges from 62- 88 Average CN ranges from 62- 88
From HEC-HMS, peak flow was estimated as 918.36 cfs From HEC-HMS, peak flow was estimated as 918.36 cfs (after 13.5 hours) for 100 years storm(after 13.5 hours) for 100 years storm
Max. water depth without outflow is 14.5 ft and with Max. water depth without outflow is 14.5 ft and with outflow is 11.9 ftoutflow is 11.9 ft
Outlet pipe length is estimated as 140 ft and diameter is Outlet pipe length is estimated as 140 ft and diameter is 3 ft.3 ft.
Trapezoidal concrete lined channel parameter are Trapezoidal concrete lined channel parameter are estimated estimated
Dam geometry was calculated and evaluatedDam geometry was calculated and evaluated
Construction was found to be $1,785,403.00 Construction was found to be $1,785,403.00
The existing dam is found to be adequateThe existing dam is found to be adequate
Future worksFuture worksFuture worksFuture works
Monitoring system designMonitoring system design
Spillway designSpillway design
ReferencesReferencesReferencesReferences
Bulloch Jr., H.E. & R.E. Neher (1980). Soil Survey of Dona Ana County Area New Mexico. United States Department of Agriculture, Soil Conservation Service
City-data.com. Las Cruces: Geography and Climate. [Online] Available: http://www.city-data.com/us-cities/The-West/Las-Cruces-Geography-and-Climate.html (Visited on 4/7/2008)
USDA (1986). TR 55: Urban Hydrology for Small Watersheds. United States Department of Agriculture – Soil Conservation Service, pp. 2-1 and 2-8