EAST GARDEN GROVE - WINTERSBURG CHANNEL Physical …

EAST GARDEN GROVE - WINTERSBURG CHANNEL

Physical Hydraulic Model Study

Project OverviewA 1:15 scale hydraulic physical model at approximately 150 feet in length has been constructed to evaluate the hydraulics of a portion of the complex East Garden Grove-Wintersburg Channel (C05) flood control system located at the I-405 Freeway in Huntington Beach and Westminster (Orange County, California). Based on the channel system’s unique geo-metric configuration, multiple confluences and complex culvert crossings, this particular reach of the channel is difficult to analyze by mathematical and computer modeling alone. An estimated $30 million in future flood control improvements are dependent on the accuracy of the hydraulic analyses at the I-405 crossing. Therefore, a hydraulic physical model of a 1,000’ reach of the channel was developed to provide the most accurate understanding of the proposed channel improve-ments. The specific physical model program objectives are to:

• Evaluate performance at design discharge• Determine maximum channel capacity• Improve channel performance

P.V.C. PIPE

HANGINGBAFFLES

SIDE WEIR

SUPPORTS RESERVOIRDRAIN OUTLET

PANEL WOOD - WATER RESERVOIRGATE VALVE

PERFORATED PIPE

Physical Model Elements Main Flume - Typical Framing Section:•Replicatesa1,000’reachoftheC05channelcenteredontheI-405Freewayculvertsystem•Modelchannelisgenerally4’wideby1.5’highexceptforthetransitionareasattheculvertentranceandexitwherethechannelwidensto5’

•Rectangularopenchannelreachesofthemodelareconstructedofplywoodwallsreinforcedwithawoodframe

•Rectangularopenchannelformedwithplywoodandcoatedwithspecializedtwo-coatwaterproofpainttomeettheFroudeLawscalerequirementsforchannelroughness

•Depthofflowatthedesigndischargeisapproximately0.7’•Channelwallsarebuilthigherthanthescaledwallheightoftheprototypeinordertocontainflowwithinthechannelsystemduringvarioustestflowconditions

TailwaterControl:•Adjustablegatesimilartothetailgateofatrucklocatedatthedownstreamendofthemodelchannelisinplaceto establish the appropriate tailwater depth for eachexperiment

•A piezometer installed in awell off to the side of themodelprovidesastablemeasurementthataveragesoutfluctuationsinthewatersurface

I-405Culverts:•The405culvertcrossingconsistsofthree10’x10’RCB’sthatare190’longtwo77”x121”ellipticalpipesthatare225ftand250ftinlength

•The triple10’x10’RCBwasmodeledwitha custom fabricated fiberglass triple8”x8”RCBwithamodellengthofalmost13’

•Theellipticalpipeswerealsomodeledwithcustomfabricatedfiberglasstoachievetheprecisemodeldimensionsof5.13”x8.07”andlengthsof16’

•Thecustomfabricationprocessallowedustomodelthecomplextransitionsfromrectangulartoellipticalatbothendsoftheellipticalpipe

HeadTank:•6’longby6’wideby9’inheightlocatedattheupstreamendofthemodel

•Hangingbafflesdissipateflowenergyfromthepumpsbeforewaterentersthemodelchannel

•Woodframedstructurelinedwithplywood•Specializedtwo-coatwaterproofpaintsealingsystem

LateralChannel:NewlandChannel •Proposed25-footwideconcreterectangularchannel(20-inchmodelscale) •100-yearflowof1,080cfs(556gpmmodel)

•Bifurcationorsplit-flowstructuretodistributeflowsbetweenexistingculvertsandmainchannelEdingerChannel •Confluenceof2largediameterellipticalconcretepipeswhichwerefabricatedforthemodelwith fiberglassusingCNCprocess

The 1:15 model scale was carefully chosen to balance the size of the model based on the construction costs and the ability to accurately measure the desired change in water surface.

Reservoir&FlumeStructureSupport:•Belowthemodelchannelandplatformisastorageres-ervoir framedwithin the vertical supportmembers oftheplatformthatcaptureandcirculatewaterfromthetailboxtotheheadtank

•The storage reservoir is wood framed and lined withseamweldedPVClinertoformawatertightbarrier

•Thedepthof the storage tank varies from30”duringoperationupto36”whenthepumpsareoff

Pumps&FlowMeasurement:•Horizontalaxialflowpumps(1,200gpmat10’ofhead),threeformainchannel(3,600gpmor8cfs)andoneforlateralchannels

•Horizontalpumpsusedinordertominimizesubmergencedepthrequire-mentsatthesuctionintake

•Electromagneticflowmetersinstalledwithaccuracyof0.2%tomonitorpumpdischargeswhicharecalibratedusingweirs

•Sharpcrestedv-notchandrectangularmetalweirsfabricatedforinstal-lationneartailboxforflowmeasurementinordertocalibratepumps/flowmeters

1

1

5

6 7

432

5

2

3

4

76

5

Length

Width

Parameter / Variable

Height/Depth

Slope

Velocity

Time (hydrograph)

Flowrate

Water Surface Difference

Froude Number

LR

LR

Froude Relationship

LR

1

LR 1/2

LR 1/2

LR 5/2

LR

1

800 ft

60 ft

Prototype

13 ft

SD/S = 0.00117 to SU/S = 0.00039

12.4 fps

6 hrs

5,910 cfs

4.0 ft

0.77

53 ft

4 ft

Model (LR = 1:15)

0.87 ft

same

3.2 fps

93 mins

6.78 cfs (3,037 gpm)

0.27 ft

0.77

MODEL PROPERTIES

Vertical Control and Adjustments:• Entire flume system supported by a series of metal “screw

jacks” located at every 12 feet which allows the fine tune adjustment of the flume elevation to 0.002 ft.

• Field surveyors (Huitt-Zollars) were utilized to lay out, set con-trol and horizontal / vertical datum to accurately construct the flume. Elevations and dimensions were checked multiple times by surveyors during construction.

Culvert Fabrication:• All culverts were constructed using rapid prototyping with

CNC (computer numerically controlled) machine tools by Manifold Works which utilized the 3-dimension CAD draw-ings of the model facilities. This allowed fabrication of very accurate elements for the model. The rapid prototyping first constructed the model elements with the CNC using high density foam. The culverts were then fiber-glassed around the foam shape of the culvert.

Waterproofing:• In order to prevent water leakage, waterproof paint has been

applied to all surfaces, along with silicone at all joints.

• The head tank, tail box and storage reservoir area lined with seam welded PVC liner material.

Model Access:• Model channel is located approximately 5’ above the warehouse floor with a 4’ wide catwalk along each side of the model channel to provide easy access to the flume for

measurements during operation and potential modifications to the channel system.

Drain and Fill Time for Experiments:• Total water storage volume of the model is approximately

23,600 gallons.• Storage reservoir has a minimum depth of 30” which is

required for proper operation of submersible pumps.• Total fill time for storage reservoir is 40 hours.• Water quality is maintained using chlorine tablets and a

traditional swimming pool filter.• A drainage line is tied into the warehouse waste line for

drainage of the model.

Special Design / Fabrication Procedures

17520 Newhope Street, Suite 200 | Fountain Valley, California 714.481.7300 | www.pacewater.com

Side Weir

I-405 Culverts

Main Flume

I-405 Downstream Culverts

Newland Channel