importanceof site considerations for abyrinth … of... · 2016-11-17 · site considerations...
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I M P O RTA N C E O F
S I T E C O N S I D E R AT I O N S F O R
L A BY R I N T H S P I L LWAY D ES I G NU P P E R B R U S H Y C R E E K D A M 7 M O D E R N I Z AT I O N
U S S D A N N UA L M E E T I N G
APRIL 12, 2016
PRESENTATION
BackgroundSite ConsiderationsHydraulic Design Approach
Empirical Published DataComputational Fluid Dynamics (CFD) ModelingPhysical Modeling
Aesthetic EnhancementsConclusions
BACKGROUND2,000+ NRCS-sponsored watershed dams in Texas
Upper Brushy Upper Brushy UCreek Watershed
NRCS Temple, 2007
BACKGROUND
7
Upper Brushy Creek WCID maintains 23 flood control dams
BACKGROUND
B r u s h y C r e e k B r u s h y C r e e kL a k e P a r k
DAM 7
Principal Principal Spi l lway
High Hazard damModernization to meet Modernization to meet dam safety requirements:
Currently passes <50% PMF
Required to pass 82% % PMF
Tropical Storm HermineTropical Storm HeSeptember 2010
B r u s h y C r e e k B r u s h y C r e e kL a k e P a r k
DAM 7
S p o r t s S p o r t s C o m p l e x
BACKGROUND
B r u s h y C r e e k B r u s h y C r e e k R e g i o n a l Tr a i l
B r u s h y C r e e k B r u s h y C r e e kL a k e P a r k
Alternatives s study in n 2013Sitetet -e-specific Challenges:
BACKGROUND
Replace e existing Auxiliary Spillway Replacee xisting Auxiliary exwith concrete labyrinth
Spillary h h weir
Pass Required FlowAvoid Modifying EmbankmentMinimize e Visibility to Park UsersIncorporate Regional Trail and ncorporate RegIAesthetics for
ional TRegor or Users
SITE CONSIDERATIONS
~7070000000000000000°
Typical NRCS Dam Dam 7
DESIGN APPROACH
Conceptual DesignPublished Empirical Data
Preliminary DesignCFD Modeling
Final Design Physical Modeling
CONCEPTUAL DESIGN
Empirical Design GuidesAssumes installed perpendicular to the flow
300-foot wide, 10-cycle labyrinth passes 55,000 cfs at design H
Crookston and Tullis, 2013
CFD MODELING10-cycle Labyrinth
Terrain and Structure Geometry
Full simulation with Flow-3D
CFD MODELING10-cycle Labyrinth Results
Flow = 49,000 cfsOvertops dam
837
Water Surface Elevation
836
CFD MODELING10-cycle Labyrinth Results: Empirical vs. CFD
837
CFD MODELING
Flow Separation
Separation due to Training Wall
Separation Regions
CFD MODELING
Alternatives• Left Training Wall Left Training Wa
Modifications
• 3 Training Vanes
• Staggered Cycles
• Arced
• Others
Results:Flow = Slight Increases,
All overtop damArced Alignment
Flow Vanes
Left Training Wall Modifications
CFD MODELING11-cycle Labyrinth Results
Flow = 50,500 cfsNo Overtopping
Water Surface Elevation
4 3
2
1
Maximum WSEL along Embankment
2
1
3
4
PHYSICAL MODEL
11-cycle Passes Required Flow
Stepped Spillway Configuration for Energy Dissipation
Potential Construction Cost Savings
1:24-scale model
PHYSICAL MODEL
Maximum WSE expected in Reservoir• Correlation to CFD Model
Maximum WSE in
Reservoir
CFD Model Extents Physical Model
PHYSICAL MODEL
Flow Separation CFD Model Comparison
Left Training Wall
Scour Potential
Stepped Spillway Configurations
Small Medium Large
PHYSICAL MODEL
Baffle Block Configurations at 20,000 cfs
Original one row One row downstream Two rows
PHYSICAL MODEL
Final configuration for Energy Dissipation
Water Surface Profile
PHYSICAL MODEL
Converging Training Walls
Cost Savings$100k
PHYSICAL MODEL
Reduced Upstream Excavation
Cost Savings$150k
MODELING CONCLUSIONS
• Costs– Modeling was ~10% of design– Modeling was 1% of construction,
estimated to save 2% of construction costsa
• Modeling was required for site-specific design– Importance of site considerations for labyrinth design– 35% reduction in discharge from standard design
• Modeling was a valuable design tool– Design development (instead of verification) – Reduced construction costs– Confidence for Engineer and Owner
AESTHETIC ENHANCEMENTS
Backfill for trail in Backfill for traBimpact basinConcrete e formlinersrs, ConcreteC e ormlinerfo rs, stain, and stamps to stain, and stampstain, annd stampnd smimic natural mimic natural mimic naturalsurroundings
Scenic Overlook
THANK YOU