1 EXAMPLE PROBLEM 378 & 410 GSS. 2 TRAINING OBJECTIVES Be able to flood route a 378 pond and design...

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EXAMPLE EXAMPLE PROBLEMPROBLEM

378 & 410 GSS378 & 410 GSS

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TRAINING OBJECTIVESTRAINING OBJECTIVES

• Be able to flood route a 378 pond and design a pond without and with a pipe.

PERM,POOL

TAILWATER ELEV

EXIT CHANNEL

INLET CHANNEL

CREST AUX.. TOP DAM

TAIL-WATER

TOP DAM-FBH +FreeboardCREST AUX.

PERM. POOL

FBH SDH PSH

CONDUIT

CREST PS

DESIGN FLOW (SDH)

TAIL-WATER

AUX. SPLWY.

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SITES 378 PROBLEM

A. GIVEN:

Drainage Area = 103 acres. Hazard Class = A1 RCN = 72 W/S length = 987’ with a slope of 2% Auxiliary Spillway Crest=Permanent Pool @ Elev. 103.6feet. No principal spillway Valley Floor Elevation - 88 feet

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Structure Data

Elev. (ft) Surface Area (Ac.)85.5 089.5 0.396.4 1.2100 4.8104.3 10.8106 11.8

107 12.4

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Rainfall: Design FBH = 8.95”

Rain distribution: Read in a 24-hr duration, rain table

No Principal Spillway Auxiliary Spillway located at 103.6 EL.

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T = Total Hydraulic Stress – lb/ft2T = Vegetal Stress + Effective Soil StressT = Tve +Te

Auxiliary Spillway has a CL material with PI=15

Allowable effective soil stress=0.05 lb/ft2

8 DAM CENTERLINE Centerline Dam Valley Profile Data:

Station (ft.) /Elev. (ft.)

0/107 26/106 69/104.3

99/103 133/100.8 163/99.6

193/98.4 223/96.9 253/96.4

283/93.6 321/89.5 371/94

401/95.2 421/95.8 451/96.9

491/103.3 521/107

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Embankment Data:

Top Width = 12’Upstream side slope = 4:1Downstream side slope =

4:1No Wave Berm WidthNo Stability BermsCrown = 0

10Auxiliary Spillway Data: We want to do a Stability & Integrity Analysis of the Spillway. You set the crest at 103.6

Station at DS end of Crest = 620Inlet length of the auxiliary spillway is about 230 ft.Profile or spillway inlet template data

(x,y) (distance, drop): 50’/0’; 280’/3.0’Bottom Width: 30 feetSpillway sideslope = 3:1Spillway slope 3% (constructed exit

channel)

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50’

280’

3’

Inlet Spillway Template

Z = 3:1

BW = 30’

Tie-in Station 6+20

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Spillway Geology and Vegetation Spillway Geology and Vegetation Data:Data:

Material in spillway - Clay (CL)PI or (lw) = 18The representative soil particle size D75 = 0.0024 inchesPercent Clay = 28% (in material in spillway)Dry Density of the clay = 92 pcfHeadcut Erodability Index = 0.1Vegetative Retardance Curve Index = 5.6 (Inlet)Vegetative Retardance Curve Index = 5.6 (Outlet)

13Assume 2 foot (2’) of rooting depth in spillwayOne foot (1’) of topsoil will be installed in the constructed channel. CL-PI=15The topsoil D75 is 0.02”.Cover Factor (assume good) bromegrass = 0.7 - 0.8Maintenance Code (assume good in constructed ) = 1Maintenance Code (assume minor irr. in natural ) = 2

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Coordinates of top of material: Sta. (ft.)/ Elev. (ft.)

100/85; 310/95; 410/106; 500/107; 700/106; 750/100; 930/95; 960/90; 1000/84

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Erosion resistant soil @ 3% exit slope.Allowable velocity = 7.0 fps.

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Smooth Bromegrass is a cool-season grass introduced into the United States from Hungary in 1884 -This leafy and sod-forming perennial spreads aggressively through both seeds and rhizomes. It grows 15 to 30 inches high and flowers during late spring and early summer in an open panicle.

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T = Total Hydraulic Stress – lb/ft2T = Vegetal Stress + Effective Soil StressT = Tve +Te

Allowable Vegetal Stress=Tva = 0.75 CiCi = Retardance Index@ Ci = 5.6Tva = 4.2 lbs/ft2 - Allowable vegetal stressTa= Allowable Total Hydraulic Stress=4.2 + .05= 4.25

lb/ft2

18PART A

FIND: Save Separate Files

1. Is this an acceptable pond design without a pipe? Y / N

A. Top of Dam= _________ EL.B. Settled Volume= ____________ CY

2. Remove all vegetation. (HINT-n=.0156. For fine-grained, cohesive soils, the value of n is taken as 0.0156) Is this an acceptable pond design without a pipe? Y / N

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PART B: Use PART A input as a start.

This pond has gullies in the upstream area of the pool. Need to design a GSS for this site. Permanent Pool @ Elev. 100.0 ft. This will cover headcuts with 2.0 ft. of water. Crest of principal spillway = 100.0 ft EL. Volume of sediment between principal and aux spw = 0.0 AF. Rainfall: PSH=1 day = 7.5”Principal Spillway Data: (Single Stage Circular Conduit)

Number of Conduits = 1Length of Conduit = 114 feetDiameter of Conduit = 12”Conduit “n” = 0.013Ke = 1.0HGL at outlet of conduit = 89.5 feet.Riser weir length = 6.28 feet. (24 inch dia.)

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No Wave Berm WidthNo stability BermsCrown = 1.0’

Auxiliary Spillway Data: We want to do a Stability & Integrity Analysis of the

Spillway. Let the program set the crest of the auxiliary spillway.

1. What is the Auxiliary Spillway Crest (ASC) _________EL.2. What is the Top of Dam (TOD) ____________EL.3. What is estimated construction volume ________CY.4. What is effective soil stress_____________lb/ft2. 5. What is the integrity distance for the spillway

analyzed.

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Part C Use Part B file as a start

Rainfall: PSH=1 day = 7.5”Use a Hood Inlet with same diameter and pipe length as

the pipe drop.Distance to bend 100’ and bend to outlet 14’.The elevation of the bend is 90 and the outlet is 89.Say the Mannings “n” = 0.013Circular weir coeff. -- 0.6Entrance coeff. -- 1.0

1. What is the Auxiliary Spillway Crest (ASC) _________EL.2. What is the Top of Dam (TOD) ____________EL.3. What is estimated construction volume ________CY.

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Part D Use Part B input file as a start

Add stability berm on the down stream side at 5’ with 25’ top width. Add a wave berm width =20’ on the front slope.

1. What is estimated construction CY?.

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Right Click on the Start button, and Select Explore.

Management of files

FOLLOW ALONG

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Highlight Local Drive (C:)

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Click - File/New/Folder

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2. Exit Explore

1. Type “SITESWorkshop” and enter

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1. Left Click the Start button/All Programs/Engineering

Applications/SITES/SITES 2005

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File / New File / New ProjectProject

Locate SITESWorkshop

and Double Click

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File / New File / New ProjectProject

Click OKTYPE EX1

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File / New FileFile / New File

File/New File

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File / Save AsFile / Save As

File/Save As

Click Save

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HOME SCREEN

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Navigating in SITES

• Home Screen

• Schematic

• Input Screens

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Schematic

• Editing File

• Dbl-click element to edit

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Input Screen -Typical• Editing data

element on schematic

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File / ContinueFile / Continue

File/Continue

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Enter Data /Next Screen

4. Class (a) dams that have a product of storage times the effective height of the dam of 3,000 or more, those more than 35 ft in effective height, and all class (b) and class (c) dams shall meet or exceed the requirements specified in Technical Release No. 60 (TR-60).

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Watershed SchematicWatershed Schematic

Click to Add Structure

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Double Click to Add Data

For This Structure

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Watershed InformationWatershed Information

Input Data and Click

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Structure Data TableStructure Data Table

InPut Data and Click

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Watershed DataWatershed Data


NRCS Curve Number Method

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Rainfall DataRainfall Data


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Rainfall Distribution Rainfall Distribution TableTable

Click Open

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Rainfall Distribution Rainfall Distribution TableTable


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Pool DataPool Data

Include planned aerated sediment, for life of structure. (optional)

Include planned submerged sediment, for life of structure.

Start Routing is required.


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Principal Spillway TypePrincipal Spillway Type


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Valley ElevationsValley Elevations


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Enter

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Enter

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Enter

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Enter

Click Next Screen

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Embankment TemplateEmbankment Template


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Auxiliary Spillway (AS) CrestAuxiliary Spillway (AS) Crest

Click

Click

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Auxiliary Spillway (AS) Auxiliary Spillway (AS) CrestCrest


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Tie Station Definition

• Downstream end of the level crest section of auxiliary spillway

• Ties station together for:– Auxiliary spillway inlet template – Geologic materials in auxiliary spillway exit

channel

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50’

280’

3’

Inlet Spillway Template

Z = 3:1

BW = 30’

Tie-in Station 6+20

63Auxiliary Spillway Inlet Auxiliary Spillway Inlet TemplateTemplate

Click

Tie-in Station 6+20

64Auxiliary Spillway Exit Auxiliary Spillway Exit TemplateTemplate


67Auxiliary Spillway Cross Auxiliary Spillway Cross SectionSection


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Auxiliary Spillway Auxiliary Spillway MaterialMaterial

Input Data

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Auxiliary Spillway Auxiliary Spillway MaterialMaterial


Next Screen

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Topsoil Fill And General Topsoil Fill And General FillFill

Input Data

Click

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Topsoil Fill And General Topsoil Fill And General FillFill


Next Screen

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Output OptionsOutput Options


Next Screen

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File / Home Screen

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Home ScreenHome Screen

File / Save As Save

Yes

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Build / Check FIle

Click

Build / Build File

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View / Summary Table

Click to Highlight

View Text

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Output TextOutput Text

Edit/Find

Click

Click

Adjust Side Bar

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Output TextOutput TextMaximize

Ta=.05 lb/ft2.OK

Velocity < Va=7.0 fps.OK

Tve=T-Te=1.66 lb/ft2.Less than allowable of 4.2 lb/ft2

OK

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Output TextOutput TextFile/Exit

ASC=103.6 El.TOD=106.4 El.

Volume=8435 CY

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Output TextOutput Text

File/Exit

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File/Save AsA2EX1nopipe.d2c

Finish EX1

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The End

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1 EXAMPLE PROBLEM 378 & 410 GSS. 2 TRAINING OBJECTIVES Be able to flood route a 378 pond and design...

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Transcript of 1 EXAMPLE PROBLEM 378 & 410 GSS. 2 TRAINING OBJECTIVES Be able to flood route a 378 pond and design...