How to Model a Vacuum Sewer in SWMM 5

Subject:  How to Model a Vacuum Sewer in SWMM 5  

You can model a vacuum sewer as a gravity pipe connected to a storage node connected to an outlet connected to various pipes in a sawtooth pattern connected to a collection tank with a pump that pumps to a force main.

1.       Gravity Pipe,

2.       Storage Node,

3.       An Outlet function that works as a function of the depth in the storage node

4.       Series of Pipes in a Sawtooth Pattern,

5.       Collection tank,

6.       Pump

7.       Force Main

http://www.sivacvacuumsewer.com/index03.html

Vacuum Sewer Example

How RTC Rules are Set in SWMM5, InfoSWMM and H2OMAP SWMM

Subject:   How RTC Rules are Set in SWMM5, InfoSWMM and H2OMAP SWMM

SWMM 5 Arrow Direction Question

Subject:   SWMM 5 Arrow Direction Question

SWMM 5 Arrow Direction Question by dickinsonre Subject:   SWMM 5 Arrow Direction Question A question often asked is what happens to the flow in a SWMM 5 link if the downstream and upstream node names are entered in reverse.    The flow will be exactly the same as if the nodes were entered in the right order but the flow in the link will be negative.  As long as the inflow to the model is at the same node in both alternate models the node depth, the link upstream depths and upstream cross sectional areas will be the same.  For example, the flow out of Nodes 80408A and 80408 will be the same but the flow out of 80408 will be negative and the flow out of 80408A will be positive. via Blogger http://www.swmm5.net/2013/08/swmm-5-arrow-direction-question.html

SWMM 5 and InfoSWMM Time Step Guide

Subject:   SWMM 5 and InfoSWMM Time Step Guide

SWMM 5, H2OMap SWMM and InfoSWMM Time Step Guide by dickinsonre Subject:    SWMM 5, H2OMap SWMM and InfoSWMM Time Step Guide If you use a variable time step in SWMM 5 or InfoSWMM/H2OMAP SWMM it is hard to gauge the proper value of the conduit lengthening.  You want to use a value that does not increase the volume of the network yet does increase the length of the shortest links so you can use a longer time step.  A good approximation to the time step that you want to use is shown in the image.   The Time Step Guide in seconds is Link Length / [Velocity + sqrt(g*Maximum Depth)] with the assumption that the velocity at maximum depth is about the value of the wave celerity for closed links or sqrt(g*Maximum Depth).  Normally (unless pumps are involved) the average time step used during the simulation is a good gauge of the time to use for the simulation.  For example, in this model run the time step used is 13 seconds which is about the conduit lengthening time step of 20 seconds * adjustment factor of 0.75 via Blogger http://www.swmm5.net/2013/08/swmm-5-h2omap-swmm-and-infoswmm-time.html

Siphon Simulation in SWMM 5 and InfoSWMM

Subject:  Siphon Simulation in SWMM 5 and InfoSWMM

Siphon Simulation in SWMM 5 and InfoSWMM by dickinsonre Subject:  Siphon Simulation in SWMM 5 and InfoSWMM  A Siphon is simulated in SWMM 5 and InfoSWMM using the basic node and link data and downstream boundary condition:  1.   Inflow can be time series, dry weather flow pattern, wet weather inflow or Subcatchment Runoff, 2.   The boundary condition can be either a free outfall, fixed or time series, 3.   The node invert, node maximum depth and node surcharge depth are defined by the user or network, 4.   The link lengths, diameters, link offset depths upstream and downstream are defined by the user of the network, 5.   The node depths, link flows, link depths and link cross sectional areas are calculated at each time based on the node continuity equation and the link momentum and continuity equation.  The link flows are a function of the friction loss, head difference across the link and the difference in the cross sectional areas of the link. 6.   In the particular model the Inflow at node MH1 fills up the MH1 depth which causes the links downstream to start flowing – the head difference across the links drives the flow up and over the siphon. via Blogger http://www.swmm5.net/2013/08/siphon-simulation-in-swmm-5-and-infoswmm.html

3 Types of Subcatchment Flow in SWMM 5

Subject:   3 Types of Subcatchment Flow in SWMM 5

3 Types of Subcatchment Flow in SWMM 5 by dickinsonre Subject:   3 Types of Subcatchment Flow in SWMM 5  1.   Impervious area with depression storage in which the runoff from the precipitation is delayed due to the depression storage.  Evaporation occurs based on the depth of water in the subarea of the Subcatchment. 2.   Impervious area without depression storage in which the runoff from precipitation is NOT delayed.  Evaporation does occur based on the depth of water in the subarea of the Subcatchment. 3.   Pervious area with depression storage in which the runoff from the precipitation is delayed due to the depression storage.  Evaporation and Infiltration occurs based on the depth of water in the subarea of the Subcatchment.    via Blogger http://www.swmm5.net/2013/08/3-types-of-subcatchment-flow-in-swmm-5.html

A Two-Dimensional Quality Mesh Generator and Delaunay Triangulator - InfoSWMM 2D Reference

Subject:   InfoSWMM 2D Reference for “A Two-Dimensional Quality Mesh Generator and Delaunay Triangulator”

Source:   http://www.cs.cmu.edu/~quake/triangle.html

SWMM 5 Clocktime RTC Rules for Pumps, Weirs and Orifices

Subject:  SWMM 5 Clocktime RTC Rules for Pumps, Weirs and Orifices

You can use the Control or RTC rules in SWMM 5 to adjust the settings of the weirs, pumps and orifices based on the clock time each day of your simulation.  Here is an example that will adjust orifice height every ½ hour for 7 orifices at one time using two sets of rules.

RULE R1a 
; Half hour setting
IF SIMULATION CLOCKTIME = 0:30:00 
OR SIMULATION CLOCKTIME = 1:30:00  
OR SIMULATION CLOCKTIME = 2:30:00 
OR SIMULATION CLOCKTIME = 3:30:00 
OR SIMULATION CLOCKTIME = 4:30:00 
OR SIMULATION CLOCKTIME = 5:30:00 
OR SIMULATION CLOCKTIME = 6:30:00 
OR SIMULATION CLOCKTIME = 7:30:00 
OR SIMULATION CLOCKTIME = 8:30:00 
OR SIMULATION CLOCKTIME = 9:30:00 
OR SIMULATION CLOCKTIME = 10:30:00
OR SIMULATION CLOCKTIME = 11:30:00
OR SIMULATION CLOCKTIME = 12:30:00 
OR SIMULATION CLOCKTIME = 13:30:00  
OR SIMULATION CLOCKTIME = 14:30:00 
OR SIMULATION CLOCKTIME = 15:30:00 
OR SIMULATION CLOCKTIME = 16:30:00  
OR SIMULATION CLOCKTIME = 17:30:00 
OR SIMULATION CLOCKTIME = 18:30:00 
OR SIMULATION CLOCKTIME = 19:30:00 
OR SIMULATION CLOCKTIME = 20:30:00 
OR SIMULATION CLOCKTIME = 21:30:00 
OR SIMULATION CLOCKTIME = 22:30:00
OR SIMULATION CLOCKTIME = 23:30:00
THEN ORIFICE R1 SETTING = 0.90
AND  ORIFICE R2 SETTING = 0.90
AND  ORIFICE R3 SETTING = 0.90
AND  ORIFICE R4 SETTING = 0.90
AND  ORIFICE R5 SETTING = 0.90
AND  ORIFICE R6 SETTING = 0.90
AND  ORIFICE R7 SETTING = 0.90

RULE R1b
; hour setting
IF SIMULATION CLOCKTIME = 0:00:00
OR SIMULATION CLOCKTIME = 1:00:00
OR SIMULATION CLOCKTIME = 2:00:00
OR SIMULATION CLOCKTIME = 3:00:00
OR SIMULATION CLOCKTIME = 4:00:00
OR SIMULATION CLOCKTIME = 5:00:00
OR SIMULATION CLOCKTIME = 6:00:00
OR SIMULATION CLOCKTIME = 7:00:00
OR SIMULATION CLOCKTIME = 8:00:00
OR SIMULATION CLOCKTIME = 9:00:00
OR SIMULATION CLOCKTIME = 10:00:00
OR SIMULATION CLOCKTIME = 11:00:00
OR SIMULATION CLOCKTIME = 12:00:00 
OR SIMULATION CLOCKTIME = 13:00:00
OR SIMULATION CLOCKTIME = 14:00:00 
OR SIMULATION CLOCKTIME = 15:00:00
OR SIMULATION CLOCKTIME = 16:00:00
OR SIMULATION CLOCKTIME = 17:00:00
OR SIMULATION CLOCKTIME = 18:00:00 
OR SIMULATION CLOCKTIME = 19:00:00 
OR SIMULATION CLOCKTIME = 20:00:00 
OR SIMULATION CLOCKTIME = 21:00:00 
OR SIMULATION CLOCKTIME = 22:00:00 
OR SIMULATION CLOCKTIME = 23:00:00
THEN ORIFICE R1 SETTING = 0.5
AND  ORIFICE R2 SETTING = 0.5
AND  ORIFICE R3 SETTING = 0.5
AND  ORIFICE R4 SETTING = 0.5
AND  ORIFICE R5 SETTING = 0.5
AND  ORIFICE R6 SETTING = 0.5
AND  ORIFICE R7 SETTING = 0.5

Hot Start Files are used to define the initial heads and flows in SWMM5

Subject:  Hot Start Files are used to define the initial  heads and flows in the nodes and links of the model.

The creation of the Hot Start File for your sanitary, combined or stormwater network is a three step process:

1.   Save the 1^st Hot Start file using an empty system as the initial conditions,
2.   Use the 1^st Hot Start file as the initial condition in the second run and Save the 2^nd Hot Start File
3.   In the 3^rd Run Use the 2^nd Hot Start file as the initial conditions of your network.
4.   It is not necessary that the Hot Start Files be exact in the initial depths or flows but only approximate so that the network in not empty. 

InfoSewer and InfoSWMM Nodes

Subject:  InfoSewer and InfoSWMM Nodes

InfoSewer and InfoSWMM are link/node networks but the nodes are of different types in both models.  InfoSewer has a distinction between loading manholes or junctions and chamber junctions that start or separate Force Main links.  InfoSewer nodes are types 1 through 4 and InfoSWMM nodes are types 5 through 8 in this image.


InfoSWMM has more generic node types than in InfoSewer so a junction can be both a Loading and Chamber Manhole if you are more familar to the InfoSewer names.

InfoSWMM 2D Layer Properties and Mesh Results

Subject:   InfoSWMM 2D Layer Properties and Mesh ID

You can use the Layer Properties for layers in the Table of Contents to see the Mesh ID and other simulation data for the 2D mesh in InfoSWMM 2D.  The Mesh ID can be seen using the Labels/Label Expression command and if you use an expression you can see the results data as well on the mesh.  The Mesh ID is used as the label as well in the 2D Output modeling report.  The Net Inflow and Net Outflow is by Mesh ID.  In this example, the flow comes out of Node 80408 to Mesh ID 131 and enters the 1D network again at Mesh ID 848.

InfoSWMM 2D Layer Properties and Mesh ID

Subject:   InfoSWMM 2D Layer Properties and Mesh ID

InfoSWMM 2D Layer Properties and Mesh ID by dickinsonre Subject:   InfoSWMM 2D Layer Properties and Mesh ID You can use the Layer Properties for layers in the Table of Contents to see the Mesh ID and other simulation data for the 2D mesh in InfoSWMM 2D.  The Mesh ID can be seen using the Labels/Label Expression command and if you use an expression you can see the results data as well on the mesh.  The Mesh ID is used as the label as well in the 2D Output modeling report.  The Net Inflow and Net Outflow is by Mesh ID.  In this example, the flow comes out of Node 80408 to Mesh ID 131 and enters the 1D network again at Mesh ID 848. via Blogger http://www.swmm5.net/2013/08/infoswmm-2d-layer-properties-and-mesh-id.html

Steady State Flow Analysis in InfoSWMM using a Ramp DWF - Method 2

Subject:  Steady State Flow Analysis in InfoSWMM using an External Flow Time Series

Steady State Flow Analysis in InfoSWMM using an External Flow Time Series by dickinsonre Subject:  Steady State Flow Analysis in InfoSWMM using an External Flow Time Series This can be easily created using a few steps in InfoSWMM.  The flow ramp is in the Routing Interface File.  The advantage is that you are able to have different ramps for the various nodes using this method. Step 1:  In Run Manager Set up the Process Models Options to use just the External Inflow and NOT the Dry Weather Flow Step 2.  Create the External Inflows File (see the help file for the format) SWMM5 Interface File 300  - reporting time step in sec 1    - number of constituents as listed below: FLOW CFS 2    - number of nodes as listed below: 36 24 Node             Year Mon Day Hr  Min Sec FLOW      36               2002 01  01  00  00  00  0.000000  24               2002 01  01  00  00  00  0.000000  36               2002 01  01  01  00  00  1000.000000  24               2002 01  01  01  00  00  1000.000000  36               2002 01  02  01  00  00  1000.000000  24               2002 01  02  01  00  00  1000.000000    This file loads two manholes with a ramped inflow up to 1000 cfs to again drown out the wet wells and cause the pumps to have a steady flow. Step 3.  Use the Tab File command and use the created External Inflows File Step 4.  Run the simulation and see if the pump flows are constant. via Blogger http://www.swmm5.net/2013/08/steady-state-flow-analysis-in-infoswmm.html

Steady State Flow Analysis in InfoSWMM using a Ramp DWF - Method 1

Subject:  Steady State Flow Analysis in InfoSWMM using a Ramp DWF

Steady State Flow Analysis in InfoSWMM using a Ramp DWF by dickinsonre Subject:  Steady State Flow Analysis in InfoSWMM using a Ramp DWF  This can be easily created using a few steps in InfoSWMM.   Step 1:  Using Scenario Explorer make a cloned Child Scenario and a cloned DWF Set which will be later modified.   Step 2:  Using DB Manager and the BlockEdit tool and increase the mean DWF by a factor of 10, 100 or 1000 to drown out all Wet Wells and cause the pumps to turn on and stay turned on during the simulation in the newly created DWF Set.    Step 3.  Run the batch manager and create two output files – Normal and Steady State for comparison.   Step 4.  You can now compare the two scenario's using Output Manager and the Compare Graph tool.  The Ramped Model should have constant flows in both links and pumps.  It was not necessary to change any of the patterns. Step 5.  The model is still  in balance – the excess DWF Inflow ends up as flooded flow and is listed as Internal Outflow. via Blogger http://www.swmm5.net/2013/08/steady-state-flow-analysis-in-infoswmm_3.html

SWMM 5 Fixed Surface Water Depth Boundary Condition

Subject:  SWMM 5 Fixed Surface Water Depth Boundary Condition

A large difference between SWMM 5 and SWMM 4 is how the Groundwater Aquifer interacts with the drainage network.  In SWMM 4 since the hydrology was simulated in the Runoff Block, the results saved to an interface file and the hydraulics were simulated in the Extran Block it was not possible to have a time step to time step interaction between the Aquifer and the Open Channels.  SWMM 5 has integrated hydrology and hydraulics so it is possible to use either a Fixed Surface Water Depth for each Subcatchment or the Receiving Nodes Node Depth Invert Elevation – the Aquifer Bottom Elevation.  The groundwater thus flows either to a fixed boundary condition as in SWMM 4 or to a time varying boundary condition.

SWMM 5 Threshold Groundwater Elevation

Subject:  SWMM 5 Threshold Groundwater Elevation

A large difference between SWMM 5 and SWMM 4 is how the Groundwater Aquifer interacts with the drainage network.  In SWMM 4 since the hydrology was simulated in the Runoff Block, the results saved to an interface file and the hydraulics were simulated in the Extran Block it was not possible to have a time step to time step interaction between the Aquifer and the Open Channels.  SWMM 5 has integrated hydrology and hydraulics so it is possible to use either a fixed Threshold Groundwater Elevation for each Subcatchment or the Receiving Nodes Invert Elevation.

Aquifers in SWMM 5

Subject:   Aquifers in SWMM 5

Aquifers in SWMM 5 by dickinsonre Subject:   Aquifers in SWMM 5  Groundwater in SWMM 5 is modeled as two zones: (1) Saturated and (2) Unstaturated.  The data for the Groundwater Simulation consists of physical data in an Aquifer and elevation and flow coefficient and exponent data in the GroundwaterData.  The Aquifer data object can be applied to multiple Subcatchments but each Subcatchment has its own set of Groundwaterdata.  For example, in this model all of the Subcatchments share the same Aquifer data but each Subcatchment has different elevation and flow data – the labels on the basin are the groundwater elevations. via Blogger http://www.swmm5.net/2013/08/aquifers-in-swmm-5.html

3 Types of Manholes in SWMM 5 and InfoSWMM

Subject:   3 Types of Manholes in SWMM 5 and InfoSWMM

There are three types of interior manholes in SWMM 5 and InfoSWMM as regards water surface elevations above the Node Rim Elevation:

1^st Excess Water leaves the Node as flooded water if the water surface elevation equals the Rim Elevation (Figure 1 and Gravity Mains),

2^nd Excess Water is  stored in the manhole as pressurized depth if the Node Surcharge Depth is used (Figure 2 and Force Mains)

3^rd Excess Water is stored above the Node Rim Elevation (Surface Ponding and Figure 3)

  

Figure 1.  The default node in SWMM 5 and InfoSWMM has just the Manhole Invert Elevation, the program calculated elevation of the highest connected link and the Node Maximum Depth or Rim Elevation.  If the Water Surface Elevation exceeds the Rim Elevation then any excess flow is lost as flooded flow.

  

Figure 2.  A force main or pressure in SWMM 5 and InfoSWMM has the Manhole Invert Elevation, the program calculated elevation of the highest connected link, the Node Maximum Depth or Rim Elevation and the Node Surcharge Depth.  If the Water Surface Elevation exceeds the Surcharge Elevation then any excess flow is lost as flooded flow but this allows more the links to have more pressure and hence more flow.

  

Figure 3.  The flooded Node option in SWMM 5 and InfoSWMM has just the Manhole Invert Elevation, the program calculated elevation of the highest connected link, the Node Maximum Depth or Rim Elevation and Node Ponding.  If the Water Surface Elevation exceeds the Rim Elevation then any excess flow is NOT lost but stored in the ponded area.  The depth of the ponded area is a function of the ponding area and the excess inflow.  If the water surface elevation goes below the Rim Elevation then the ponded volume flows back into the network.