Design of the South Doña Ana Dam Design of the South Doña Ana Dam Project Members: Project Members: Daneel Nortier Daneel Nortier Desh Raj Sonyok Desh Raj Sonyok Tran Tri Dung Tran Tri Dung Umaima Al-Aqtash Umaima Al-Aqtash Civil Engineering Department Civil Engineering Department New Mexico State University New Mexico State University International Engineering Group (EIG) International Engineering Group (EIG)
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.
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Design of the South Doña Ana DamDesign of the South Doña Ana Dam
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)
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
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
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