Section 4: Pond Storage

Transcription

1 Section 4: Pond Storage Defining and calculating pond storage 55 Minutes Press Space, PageDown, or Click to advance. Press PageUp to reverse. Esc to exit. Right-Click for other options. Pond Storage Introduction Defining a volume that can fill with water P Most ponds require a description of their storage capability P HydroCAD provides many options for defining pond storage... Copyright 2004 HydroCAD Software Solutions LLC All Rights Reserved - Duplication Prohibited Pond Storage Calculations HydroCAD provides many techniques Prismatoid Storage A volume with a rectangular base & four equally sloped sides Prismatoid Cone/Cylinder Horizontal Cylinder Parabolic Arch Prefab Chamber Custom Storage < Base width & length < Height < Side Z (Run/Rise) Set Z=0 for vertical sides PUsed for: < Rectangular vaults < Some excavations 1 Z Let s review each of these options

2 Vertical Conic Storage A volume with a circular base & any side slope < Bottom diameter < Height < Side Z (Run/Rise) Set Z=0 for vertical sides P Used for: < Circular dry-wells < Catch basins < Circular excavations Horizontal Cylinder Storage For a circular tank or pipe storage < Diameter < Length < Slope (0 if level) Slope feature added in upcoming HydroCAD 7.1 P Used for: < Pipe storage < Pipe embedded in stone Details coming up later! Parabolic Arch Storage For an (underground) parabolic arch < Bottom width < Height < Length P Used for: < Generic chamber storage < Can be embedded in stone Details coming up later! Prefab Chamber Storage For specific prefabricated storage chambers < Specific chamber data CULTEC data pre-defined Other chambers can be added < Length Preset for specified chamber P Used for: < Precise chamber storage < Can be embedded in stone Details coming up later! 4-070

3 Custom Pond Storage Multiple options for any other type of storage! P 1) Enter cumulative storage directly < Useful if you already have the data < But does not allow area calculations P 2) Enter incremental storage < HydroCAD adds all the slices to determine the cumulative storage P 3) Enter surface area at each stage < Storage is calculated automatically < Several options for volume calculation... Storage by Surface Area #1 Several methods for converting surface area to storage P Prismatic Sections < Horizontal sections of a prism May have 0, 1 or 2 sloped sides < Uses average area method P Pyramidal Sections < Square base < Sloped or vertical sides A 2 A 1 A 2 A Storage by Surface Area #2 Several methods for converting surface area to storage P Conic Sections < Circular base < Sloped or vertical sides P Irregular Sections < Same volume as conic sections < Accurate wetted area for elongated shapes A 2 A 1 A 2 A 1 Compound Storage Each pond can use multiple storage definitions PAll defined volumes are added together < Water surface elevation must be same in all PCan use any combination of storage < For example, one pond could include: Parabolic arch (underground storage) Vertical cylinder (connection to surface) Custom storage (above-grade storage)

4 Pond Storage Multiplier Prevents duplication of storage definitions PThe Storage Multiplier makes it easy to model several identical volumes < All volumes must be at same elevation < & have same water surface elevation Using the Void Ratio Allowing for reduced storage PVoid Ratio allows for reduced storage < Adjusts for sand, gravel, or stone fill PMaintains overall wetted-area for exfiltration X 2 = + X 70% voids = Embedded Storage Example #1 A simple combination of basic features PPerforated pipes in a stone bed < First define the outer stone bed Use any standard storage definition (prismatoid, etc.) Set the correct void ratio for the backfill < Then define the inner storage volumes(s) Set each chamber to Embed in the outer storage Embedded Storage Example #2 Complex storage setups are quick and easy PCombine different shapes < You can even include the connectors... < And any above-grade storage!

5 Embedded Storage Example #3 Complex storage setups are quick and easy PUse any desired configuration < Different pipes at different elevations < Varying backfill with different void ratios Level Pool Storage All voulmes within a single pond must maintain the same water surface elevation! P Can equalize through perforations P -or- by direct connections Overfilled Storage All storage definitions are closed P What happens when a storage volume fills up? < HydroCAD-7 no longer extrapolates storage < YOU must define any overflow storage < Otherwise the storage volume is capped and head (pressure) will be developed This allows modeling of closed storage volumes Overflow Storage If you wish to avoid a pressurized situation, you must define any active overflow storage Any road culvert may cause ponding Consider each culvert as a possible pond P Any point in your model that may detain water is considered to be a pond P For a road culvert, the pond storage is the area that would be inundated at the inlet P This storage must be known in order to accurately determine the culvert headwater, and hence the flow 4-185

6 Zero-Storage Ponds Why have a pond with no storage? PFor modeling ponds with insignificant storage < Such as catch basins PSince there is no storage: Qout = Qin < No storage = no detention! PSo what good is a zero-storage pond? < Makes it easy to model catch basins Just enter the culvert outlet, plus any other devices < Indicates the headwater (HGL) on outlet devices Can be used as the tailwater for upstream nodes! Software Exercises Exploring these topics in HydroCAD PBefore we begin the software demonstration, are there any other questions about pond storage calculations? PIf you wish, you may perform the following exercises yourself, or just watch the demo Getting Started Prepare a new project file Prepare a New Pond Each pond contains storage information P Get ready: < Start HydroCAD < Create a new project called Seminar1 If the project already exists, delete the old file first P Prepare a pond to receive the storage data: < Drag a pond from the palette < Edit the pond < Select the Detention Pond option < Select the Storage tab < Remove check from Large Units This allows us to use Cubic-Feet instead of Acre-Feet

7 Pond Storage Options #1 Pond Storage Options #2 P Explore the storage options: < (You should already be on the Storage tab) < Double-click a blank storage line < Enter a new storage definition: Select Prismatoid and click OK Invert elevation = 100' Width = 10' Length = 20' Height = 10' < Click OK to save the prismatoid definition P Lets add some more storage: < Vertical cone or cylinder Description = Drywell Invert Elevation = 100' Diameter = 10' Height = 8' < Horizontal cylinder Description = Pipe Storage Invert Elevation = 102' Diameter = 48" Length = 100' Pond Storage Options #3 Pond Storage Options #4 P Lets add some more storage: < Parabolic arch Invert = 100' Width = 48" Height = 24" Length = 100' P Lets add a prefabricated chamber: Skip to Chamber Model field Select Chamber Model = Acme 100A This sets size and layup length Storage Multiplier = 10 This sets the number of chambers! Set Invert = 100'

8 Pond Storage Options #5 Viewing Storage Results Examining the final pond storage P Lets add some more storage: < Custom stage-storage Select Surface Area method Enter desired stage-area data: 100' elevation -> 250 SF 101' elevation -> 350 SF Select any desired shape P Click OK to save all pond data P Open the pond report: < Double-click the pond < Explore the Summary report Note the detailed storage breakdown < Explore the Storage report Shows the overall pond storage P Close the report window Embedded Storage Example #1a Defining complex storage arrangements Embedded Storage Example #1b Defining complex storage arrangements P Prepare another pond: < Create a new pond < Double-click to edit < Select Detention Pond < Select the Storage tab < Uncheck Large Units P Define the outer storage volume Create prismatoid storage volume Set invert at 100' Set size to 10'x20'x5' high Leave Side-Z=0 (for vertical sides) Set 50% void ratio for gravel fill Click OK to save outer storage definition

9 Embedded Storage Example #1c Defining complex storage arrangements PDefine the embedded perforated pipe Create a horizontal cylinder Set invert=100.5' Set Diameter=48" Set Length=40' Or set Length=20' & Storage Multiplier=2 Set Embed inside Volume 1 (the prismatoid) Leave Voids=100% (the pipe is empty!) Click OK to save pipe storage definition Embedded Storage Example #1d Examining the storage results P Click OK to save the pond data P Examine the pond report: < Double-click the pond < Explore the Summary report Note the embedded storage calculation < Explore the Storage report Note the inflection at the top/bottom of the pipe P Close the report window Using Perforated Pipe *** End of Section *** Level Pool and exfiltration issues P Pond routing assumes that the water surface elevation is constant in all storage volumes. P Exfiltration is calculated at the outer storage surface, not at the perforations. < Exfiltration details in the next section! PAre there any other questions about pond storage? PFor detailed pond storage equations, please see the HydroCAD Owner s manual. PIf you performed the exercises, you may close HydroCAD at this time. < SAVE YOUR CHANGES when asked