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