Overview

The purpose of this technote is to briefly review the features and use of the Post Calculation Processor available in WaterGEMS and WaterCAD. Additional information can be found in the Help section for WaterGEMS or WaterCAD.

Background

The Post Calculation Processor is a tool that allows you to run simple statistical analyses on results obtained from computing an extended period simulation (EPS). These results can be displayed in the element properties or FlexTables as User Data Extensions.

Post Calculation Processor Properties

The Post Calculation Processor is a simple dialog consisting of a few fields, including the start and stop times, the statistic you wish to compute, the WaterGEMS property field the analysis will be run off of, the output property (or User Data Extension), and the operation type.

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There are also Delete and Select From Drawing icons, as well as the Calculate button that will run the statistical analysis.

Opening Post Calculation Properties

The Post Calculation Processor can be accessed by going to the Analysis pulldown and selecting Post Calculation Processor. It can also be open from the Post Calculation Processor icon in the toolbar.

After selection this, a small Select dialog will open.

This common tool in WaterGEMS that allows you to choose the elements that will be included in the analysis. The default setting for the dialog is that the Add icon is selected. With this, you can click on any element in the model for inclusion in the analysis. It will highlight in red on the drawing pane. Conversely, you can also remove selections by choosing the Remove icon. The Select dialog also allows for you to choose a selection based on a polygon or query. Unless you are selecting only a few elements, the Query icon may be the most efficient as it allows you to select an already-created Selection Set of elements.

Note: For more information on Selection Sets, please review the Help topic on that subject.

Once you have selected the elements in the drawing, choose the green checkmark icon. The Post Calculation Processor dialog will then open.

Note: You can select the elements for analysis later if you wish. To do this, choose the green checkmark icon without making a selection on the drawing pane. The Post Calculation Processor will then open. You can then select the “Select from Drawing” icon in the Post Calculation Processor, which will open the Select dialog described above.

User Data Extensions

As mentioned earlier, the Post Calculation Processor requires the analysis results to be saved into an existing User Data Extension (UDX). The UDX can either be created ahead of time or from the Post Calculation Processor. The UDX dialog can be accessed directly by going to Tools > User Data Extensions.

Note: You can also open the UDX dialog directly from the Post Calculation Processor dialog by select the ellipsis (…) button next to the Output Property field.

To create a UDX, highlight the element and select the New icon. The section on the right will fill in with default data. More than likely the results of the statistical analysis of the Post Calculation Processor will be a “real” number, or a non-integer. Because of this, change the Data Type to “Real”. When this is completed, the Units section will appear. Enter the appropriate Dimension, Storage Unit, and Numeric Formatter for analysis you will be conducting. You should also change the label to something recognizable for the analysis. Once you have done, select Okay.

Note: Once you select Okay, some fields such as Data Type, Dimension, and Storage Unit cannot be changed or edited.

Running a Statistical Analysis

Once the User Data Extension is created, you are ready to run a statistical analysis. The Post Calculation Processor is capable of simple statistical analyses, such as means, standard deviations, and sums. A complete list is available by selecting the Statistical Type dropdown menu.

Note: For more complicated calculations, the latest release of WaterGEMS and WaterCAD has the capability of creating formula-based User Data Extensions. For more information on this, see the Help menu or the Creating Formula-Based User Data Extensions technote.

To run the analysis, first make sure that you have selected elements in the model. A list will appear in the bottom window of the Post Calculation Processor. Next, choose the start and stop time for the analysis. Then, select the Statistic Type.

Next, select the Result Property. This is the element property you analyzing. The dropdown will contain all of the Results properties for the element type selected. After making this selection, choose the UDX you created from the Output Property dropdown. Lastly, select the Operation. The most common will be “Set”, though you can also choose to add, subtract, multiply, or divide.

Finally, click the Calculate button. The program will run the calculation and a dialog will appear stating that it is complete and display the number of elements affected.

Viewing Results

Since the results are saved into a user data extension, you can view the results in either the element properties or the FlexTables.

To see the results in the properties, doubleclick on one of the elements that were analyzed to open the Properties dialog. You will find the name of your UDX under the section “User Defined”.

To see the results in the FlexTables, open the element FlexTable (through View > FlexTables, for instance). With the FlexTable open, select the Edit icon. Scroll through the list on the left to find the UDX field. The list is in alphabetical order. Select the Add button and it now appear in the list on the right. Click Okay to return to the FlexTable. The statistical analysis results should now be available.

This data is also available for results presentation in graphs and data tables.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Water and Wastewater Forum

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

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How do I open an existing WaterGEMS model inside ArcMap?

First, open ArcMap. Then, click the WaterGEMS V8i menu, choose "Project" > "Add Existing Project". Select your WaterGEMS model and then click the blue folder icon in the next window, to attach a geodatabase. A separate geodatabase is necessary for ArcMap to interact with the WaterGEMS model. It is recommended that you save a new geodatabase. For example, name it MyModelgdb.mdb and save it in the same folder as your WaterGEMS model.  Note: If you get a message that says "WaterGEMs project canot be a geodatabase" this means that the name you tried to give your geodatabase has the .wtg extension in it. Simply remove the extension and your new geodatabase will be created.   Ensure that you assign the correct coordinate system/spatial reference, before clicking OK in the window that shows the blue folder icon. When you click OK, the Table of Contents will be populated with the WaterGEMS element types and your model should appear. You may need to use the zoom extents button or zoom to an element using the search button at the top of the WaterGEMS properties window.

Note: your WaterGEMS model must be saved in V8 XM or V8i format already (.wtg file). If you are trying to open a WaterCAD V7 and below model, you must first open it in the Standalone platform of WaterGEMS V8i and save it in V8i format.

How do I create a new WaterGEMS model inside ArcMap

First, open ArcMap. Then, click the WaterGEMS V8i menu, choose "Project" > Add new project. Choose a location to save the WaterGEMS model and then click the blue folder icon in the next window, to attach a geodatabase. A separate geodatabase is necessary for ArcMap to interact with the WaterGEMS model. It is recommended that you save a new geodatabase. For example, name it gdb.mdb and save it in the same folder as your WaterGEMS model. Ensure that you assign the correct coordinate system/spatial reference, before clicking OK in the window that shows the blue folder icon. When you click OK, the Table of Contents will be populated with the WaterGEMS element types and you can now lay out or import your WaterGEMS model.

How can I convert my GIS to a WaterGEMS model inside ArcMap?

First, follow the steps above for creating a new WaterGEMS model. Then, use Modelbuilder to import the GIS. Modelbuilder is located under the "Tools" menu inside the WaterGEMS V8i menu. Select ArcGIS geometric network or ArcGIS Geodatabase features as the data source type, select your geodatabase features to import and follow the subsequent steps. 

What is a Geotable?

A geotable is similar to a flextable, but determines which fields/attributes are included in the WaterGEMS geodatabase when working inside the ArcGIS platform. ArcMap interacts directly with the personal geodatabase associated with the WaterGEMS model, not the WaterGEMS database (.wtg.mdb). The fields selected in the geotable are the fields linked between the WaterGEMS model database and the geodatabase. ArcMap can then apply symbology effects from the available geotable fields.

What are some operations that I should NOT be performing in WaterGEMs for ArcMap?

 There are two operations that you should NOT perform when in WaterGEMS for ArcMap session:

1. DO NOT add your own field to a WaterGEMS layer (Pipe, Tanks, Junction, etc...).
2. DO NOT add files or manipulate anything in the WaterGEMS geodatabase file.

Performing either of these operations could potentially corrupt the feature class in the WaterGEMS geodatabase or cause some kind or disconnect between the geodatabase and the WaterGEMS project files making the files unreadable.

Can I add field to a WaterGEMS layer without corrupting the feature class or geodatabase?

Yes, you can add your own custom fields to a layer in your feature class but, it needs to be done through the WaterGEMS interface. What you'll need to do is click on the WaterGEMS toolbar and find the Tools menu. Off the Tools menu you should look for User Data Extensions and select it. This will open the user data extension manager where you can create a field for any one of your WaterGEMS elements. Details about how to use this feature can be found in the help documentation by searching the keywords "User Data Extension" or can be found here for "Creating Formula Based User Data Extensions".

Which versions of WaterGEMS support which versions of ArcGIS?

* Officially certified for this version only. 

I've integrated WaterGEMS with ArcGIS and I have the correct versions, but I don't see the WaterGEMS menu. Why?

In ArcMap, right click in the gray area at the top-right corne. You should see several WaterGEMS entries available to add as toolbars. At a minimum, make sure "WaterGEMS layout toolbar" is selected. 

If I'm working in ArcMap without a WaterGEMS model open, am I still using a WaterGEMS license?

For version 08.11.00.30 and below, you will still be using a WaterGEMS license. To prevent this from happening, you would need to first un-integrate WaterGEMS from Arcmap by using the "WaterGEMSXMUnreg.exe" file, located in the installation folder. Please be sure you have the latest cumulative patch set applied, before attempting this.

In the next version of WaterGEMS, license usage will only be recorded if you have an open WaterGEMS project in your ArcMap session.

After working on a project in ArcGIS mode and saving an .mxd, why does the WaterGEMS model not appear when reopening the .mxd? 

The .mxd file is not linked to the WaterGEMs files so, after reopening the map, you must load the WaterGEMS project, under WaterGEMS > View > Project Manager. 

When working in ArcGIS mode, why are the tools in the WaterGEMS layout toolbar grayed out? 

First, you must open or create a WaterGEMS model in your current map, using the Bentley WaterGEMS > Project menu. Also, you must be in editing mode to use the tools. Go to Editor > Start Editing.  

How can I enable the flow arrows and active topology colors when working in ArcGIS mode? 

Go to Bentley WaterGEMS > View > Apply WaterGEMS renderer. Once the Renderer is applied, you can use the "show flow arrows" check box, under the same menu.

What is the easiest way to color code WaterGEMS elements inside the ArcMap platform?

First select the element type layer from the table of contents. Once this is done the layer will be highlighted in blue. Next click the Bentley WaterGEMS V8 menu and choose Tools > Layer Symbology. This tool will allow you to use the familiar WaterGEMS color coding interface to automatically create ArcMap symbology entries.

How do I remove a color coding from a WaterGEMS layer?

First right click on the layer you want to remove the color coding from in the table of contents and then select 'Properties' from the pop up menu to open the layer properties dialog. Now navigate to the Symbology tab and look on the left hand side of the dialog box (see image below). Here you should see that 'Quantites' - 'Graduated Colors' is selected. All you need to do now is click on 'Features' instead of 'Quantities' and then click Apply, OK. The color coding should be removed from the layer.

How do you make elements inactive so they don't show up like you can do in the WaterGEMs standalone? 

There are actually two way to do this. 1) First make sure the WaterGEMS Renderer and Auto Refresh are on (WaterGEMS toolbar > View > WaterGEMS Renderer / Auto Refresh). Now that you have the Renderer active if you had any elements that were already set inactive they should no longer be displayed in your drawing pane. To check which elements are inactive you can add the 'Is Active?' field to your Geotable. You'll have to start an editing session in order to do this.  2) The second way you can make elements inactive so they don't display in your drawing pane is to create a color coding. Locate the layer that you want to make elements inactive for and right click on it. Select 'Properties' on the pop up dialog box and click on the Symbology tab of the layer properties dialog. Now click on the 'Categories' option on the left side of the dialog box (see image above). The 'Categories' - 'Unique values' should be chosen by default. Now in the value field choose "Is_Active" from the drop down menu and click the 'Add All Values' button to populate the symbol area. You should now see two symbols: a) <all other values> a.k.a - False or 0, indicating this symbol is linked to the color coding for the elements that are inactive and you don't want to be displayed in your drawing pane b) 1 a.k.a - True, indicating this symbol is linked to the color coding for the elements that are active and you would like to be displayed in your drawing pane. Now you can either uncheck the checkbox to the left of <all other values> or you can double click on the symbol to the left of <all other values>. If you chose to double click on the symbol then what you will be doing next is setting the color of this symbol to   "No color" in the symbol selector box and then selecting OK to close this box. Finally, you will select Apply and then OK on the Layer properties dialog box to save your changes and display your layers as you desire.

When annotating or color coding in the ArcMap platform, why aren't all the WaterGEMS attributes available?

The attributes available to color code and annotate on are based on the attributes included in the geotables. So, click the Bentley WaterGEMS V8 menu > View > Flextables. In the Flextables manager, open the "Geotable" corresponding to the element type in question. The fields shown in this table will be linked to the geodatabase and thus will be available to ArcMap for symbology. Use the yellow 'edit' button to add or remove attributes.

I'm double clicking on my elements and the properties for the element aren't appearing. Why?

In order for your element properties to appear you'll need to make sure you are double clicking on the elements in your drawing pane with the WaterGEMs arrow cursor. The WaterGEMS arrow cursor is located on the WaterGEMs layout tool and is the first icon on the bar.

What is the best procedure to take to when creating a shapefile or feature class to help ensure that when I bring a model in using modelbuilder I won't run into problems with pipes or junctions not being connected correctly?

The best way to help ensure that everything comes in correctly using modelbuilder starts when the file that you are trying to bring in is created in ArcMap. When creating the file you should make sure to turn on all your snapping options so the elements are actually connected in ArcMap and there aren't gaps between the elements. Another thing that you want to do is make sure that you are laying out the elements correctly according to WaterGEMS rules. This means that every pipe needs to have some type of node element attached at either end. Node elements include junctions, tanks, valves, reservoirs, and pumps. If possible it's also advised to create a new pipe between each two nodes elements. This means that instead of laying out all your pipes first when creating your shapefile (feature class) you would create things in the following manner:

1. Create a node element
2. Create the line element representing the pipe
3. Create the end node element for the line
4. Repeat steps 1-3 until finished.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]  

WaterGEMS V8 Modeling FAQ 

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

How does the Automated Fire Flow analysis work? 

The automated fireflow analysis routine will perform a series of independent steady state calculations, with various extra demands applied to your fireflow nodes. It first runs a steady state analysis on the scenario in question, with the "needed" fireflow applied only to one of your fireflow nodes. It checks the resulting pressure at that node, at other nodes in the same zone and (if desired) pressure at all other nodes in the model and velocities in the pipes. If these are within the constraints specified in your fireflow alternative, it will add a little bit more demand to that node, check the pressures, and repeat, until the pressure constraints are violated or the demand reaches the "upper limit" that you specify. In then reports this "available" fireflow and moves on to the next fireflow node, performing the same steps. 

The hydraulic results seen in my junction/pipe table and element properties do not seem to account for fire flow. Why? 

After the fireflow calculations are complete, WaterCAD/GEMS computes an additional steady state simulation, without any fire flow demands. This establishes baseline results for the model and is what you see in the element properties and flextables. To see results for fireflow calculations, you must check in your Fire Flow report (flextable) or in the "Results (fire flow)" section of the properties. To see hydraulic results for elements other than the fire flow nodes themselves, you must use the Fire Flow Results browser.

Why do I see "N/A" for all my nodes in the fireflow report (flextable)? 

You may not have your calculation option set to perform the automated fireflow calculations. Go to Analysis > Calculation options. Double click the calculation option set associated with the scenario in question (designated by the red check mark) and change the "calculation type" to "fire flow". Also ensure that you are not encountering any red user notifications, which indicate a critical data-entry problem that prevents the model from being calculated. Note that "N/A" entries can also be caused by omission from the fireflow selection set. In your fireflow alternative, make sure that all the nodes you'd like to study are included in the selection set selected for "Fire flow nodes". The fireflow routine will only analyze and provide results for nodes in this selection set.

How do I remove the "N/A" entries in the fireflow report for nodes not included in my fireflow nodes selection set?

In cases where a selection set is chosen for the "fire flow nodes" field in your fireflow alternative, results will not be computed for nodes not included. In this case, you can filter the fireflow report/flextable using one of the two methods:

1) Open the selection set manager, double click the selection set used in your fireflow alternative, right click anywhere in the drawing pane, choose "edit group" and open the fireflow report.

2) Open the fireflow report/flextable, right click any column header > filter > Custom. Filter like this: Fire flow iterations > 0

Why do I get zero available fireflow for one or more nodes in my fireflow report? 

This is likely due to the pressure or velocity constraints being violated, even with the baseline demands. Check the "calculated residual pressure", "calculated minimum zone pressure", "calculated minimum system pressure" (if using this constraint) and "velocity of maximum pipe" (if using velocity constraint.)

My fireflow report shows fireflow nodes failing due to low pressure at the suction side of a pump. What can I do about this? 

If you are not concerned about this, you can create a special "low pressure" zone and select that as the zone for the node in question. This way, it will not be considered in the automated fireflow analysis (unless you select to have a minimum system pressure constraint.) However, you may want to make sure the reservoir elevation upstream of the pump is correct and that the pump intake pressure meets the minimum NPSH requirements. 

What is the Fire flow results browser used for? 

The fire flow results browser is used to check results for others elements in your model, during individual fire flow runs. Say for example you wanted to see the exact pressure distribution, valve status and pipe velocities when fire flow was applied to Hydrant #1. Say for example Hydrant #1 had a total available fireflow of 1000gpm. Selecting Hydrant #1 in the fire flow results browser would switch the calculated results shown in element properties (and flextables) to show the results of the model when the consumption (demand) at Hydrant #1 was 1000gpm. You could then color code pressure, check velocities in the pipe report, etc. You could also easily check other fire flow nodes' "auxiliary" results by simply clicking them on the list. Before using this tool, ensure that the fire flow auxiliary results type and output selection set are chosen, in your fire flow alternative.  

What if I want to see how much pressure is available exactly at the total needed fire flow? Do I need to set the upper limit equal to the needed fire flow?

No, you don't. Click the yellow edit button at the top of the fire flow flextable and add the fields "Pressure (Calculated residual @ total flow needed)" and "Pressure (Calculated zone lower limit @ total flow needed)". These will show you the residual pressures exactly at the total needed fire flow, instead of showing at the total available. 

Is there an easier way to check residual pressures at a hydrant, for a range of flows? 

Yes. With normal base demands entered for your model nodes, simply right click on the hydrant/junction and choose "Hydrany flow curve". This will generate a curve of flow versus pressure. Basically it will run several steady state simulations with various demands on that node, reporting the pressure at the node for each one. For example, if you wanted to see how much flow could pass at 20psi, you could simply look up the flow for 20psi on the hydrant flow curve. 

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

[[General WaterGEMS V8 FAQ|General WaterGEMS V8 FAQ]]  

WaterGEMS V8 Modeling FAQ 

[[WaterGEMS for ArcGIS FAQ|General WaterGEMS for ArcGIS FAQ]] 

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Will the minor losses associated with pipe bends be automatically accounted for? 

No, you must enter the appropriate minor loss coefficient in the properties of the pipe. A library of typical values for various bend angles are included, which you can choose from. 

How can I model a pipe bend without placing a junction? 

In the standalone platform, hold down the CTRL (Control) key while laying out a pipe; left-clicking will lay out a bend vertex instead of a junction. 

Can I model fluids other than Water?

Yes, you can. You can define new liquids under Components > Engineering Libraries > Liquid library, by way of the specific gravity and kinematic viscosity. You can then select your custom liquid in your calculation options (Analysis > Calculation Options). Note that only Newtonian liquids are valid, and you might need to adjust your pump definitions if the viscosity of your fluid differs from water. Furthermore, as Hazen-Williams friction method is an empirically based formula, its calculated friction losses are only applicable to Water @ 20 deg C. It should not be used for other liquid types (and you should use Darcy-Weisbach instead).

How can I add a new material such as HDPE to the material library?

1. Go to Components > Engineering Libraries and click the plus sign next to "Material Libraries"
2. Right click MaterialLibrary.xml and choose "add item" - a new material entry will appear at the bottom of the list.
3. Right click this new material entry, choose rename and enter the name (such as 'HDPE').
4. On the right side, enter the friction coefficients for your new material, then click close.

If you would like to create a new engineering library (xml file) instead of altering the default MaterialLibrary.xml, simply right click on "Material Libraries", choose "create library", choose a location to save the file, then repeat steps 2-4 above, replacing 'MaterialLibrary.xml' with the name of your library.

How can I model a steady state simulation with demands from a specific time of the day? 

If your steady state simulation represents a certain time of the day and you'd like the appropriate demands to be used, based on your demand patterns, you can use the EPS snapshot feature. Go to Analysis > Calculation options. Double click your calculation option set and choose "True" for "Is EPS Snapshot?". Then, select your date/time. When you compute the steady state simulation, it will use demands based on the multiplier on your demand patterns. Note that if your pattern timestep (increment of the time column) is less than 1hr, the computed demand will be "smoothed" based on the average of the multiplier from that timestep and the next. 

Should I use the inside diameter or outside diameter for the "diameter" field for my pipes? 

WaterCAD and WaterGEMS use the inside diameter (ID) for calculations. So, you should enter the inside diameter for each pipe's "diameter" field.

Nominal Diameter for most common material types is close enough to Internal Diameter to be used directly for modelling. However, you should be careful for some materials, as the manufacturer's expressed "nominal diameter" may refer to the outside diameter, which could be substantially different from the inside diameter. Discrepancies in model calibration are usually related to errors in roughness coefficients, not diameters.

How can I find the total volume of water through a certain element? 

Right click on the element and choose "totalizing flow meter". In this tool, you can select the timeframe and report water volume. 

How can I model a backflow preventer? 

You can do this with a General Purpose Valve (GPV) and a check valve. In the valve properties, enter a table of flow versus headloss. Make sure the orientation of the adjacent pipe is correct and then choose "True" for "has check valve?". If a certain amount of head is required to push open a closed check valve, it may be desirable to include some special entries in the GPV curve: 0,0 and 0.001,X, with ‘X' being the head value above which the valve can reopen.  

How does the Pressure Sustaining valve (PSV) work?

 A pressure sustaining valve (PSV) tries to maintain the upstream pressure or hydraulic grade at a user-defined pre-set value. In order to achieve its pressure sustaining ability, a specific headloss will be induced through the PSV, such that energy balance across the model results in the upstream pressure obeying the setting.

The valve can be in one of three states:

- Partially opened (i.e., active/throttling) to maintain its pressure setting on its upstream side when the downstream pressure is below this value.
- Fully open (inactive) if upstream pressure exceeds setting or if the downstream pressure is above the setting.
- closed if upstream pressure falls below setting or if downstream pressure exceeds upstream pressure.

Example: PSV setting is 55psi
Upstream pressure = 50 then valve closes
Upstream Pressure = 55 and downstream pressure = 60 then valve closes
Upstream pressure = 65 then valve opens
Upstream pressure = 55 and downstream pressure = 45 than valve controls

How does the Pressure Reducing valve (PRV) work?

A pressure reducing valve (PRV) will throttle the flow to prevent the downstream pressure or hydraulic grade from exceeding a user-defined pre-set value. In order to achieve its pressure reducing ability, a specific headloss will be induced through the PRV, such that the resulting downstream pressure obeys the setting.

The valve can be in one of three states:

Valve is CLOSED if downstream pressure exceeds the pressure setting or is greater than the upstream pressure (to prevent reverse flow).
Valve is OPEN if upstream pressure is less than setting and downstream pressure is less than upsteam pressure.
Valve CONTROLS if upstream pressure is greater than setting and downstream pressure equals setting.

Example: PRV setting is 55psi
Downstream pressure = 65 then valve closes
Upstream Pressure = 45 and downstream pressure = 50 then valve closes
Upstream pressure = 45 and downstream pressure = 40 then valve opens
Upstream pressure = 70 and downstream pressure = 55 than valve controls

What happens when a tank becomes empty or full?

When the water level in the tank reaches the minimum or the maximum (as specified in the properties), a built-in altitude valve will close the adjacent pipe. An empty tank will close the downstream pipe, since it cannot drain any more and a full tank will close the upstream pipe, since it can't fill any more. Once the opposite conditions occur in the system, the pipe(s) will open back up.

This can present a problem in some systems, because for example, as soon as the pipe closes for an empty tank, it may instantly be able to fill again from another pipe, triggering the pipe to reopen. As soon as the pipe reopens, it drains to empty, closing the pipe again. This can cause excessive intermediate timesteps and rapid oscillations in the system. So, it is suggested that you configure your controls (typically pump controls) such that the tanks never become full or empty. (Example:  If your tank fills at an elevation of 90 ft. you might want to set your pump to shut down at 89.9 ft or if your tank empties at a level of 2 ft. you might set your pump control to shut down at 2.1 ft.)

How can I model a connection to an existing water main? 

It is always best to model all the way back to the water source, at least using skeletonized data. If you cannot do this, the best approximation would be to conduct static and residual hydrant tests at the connection location and enter that information in the model as a reservoir and pump. For more detailed information, see the "modeling tips" section of the User Guide, which you can download at Docs.Bentley.com > Geospatial > Bentley WaterGEMS > XM Edition user guide.

How can I model a Top Feed/Bottom Gravity Discharge Tank? 

You can do this by placing a Pressure Sustaining valve (PSV) upstream of the tank, with the hydraulic grade setting equal to the elevation of the top of the tank. For more information, see the "modeling tips" section of the user guide. 

Why does my pump system head curve look strange when I only have demands downstream? (no tanks or reservoirs) 

The system head curve option is invalid for this condition, because a range of flows cannot be tested. This is because the pump can only operate at one point: the flow value equal to the sum of all demands, with the corresponding head value. The scale exaggeration throws off the graph; really what you're seeing plotted is a near-vertical line for the system head curve.  

How does the gas law model work for a hydropneumatic tank? 

Given the initial level/HGL and liquid volume, the gas law model keeps the "nrt" part of the equation constant (called K) and is thus able to compute HGL for a given volume, or vice versa, as the conditions in the model change over the course of an EPS simulation. One should still use controls to turn the pump on/off based on the minimum/maximum level/HGL in the hydropneumatic tank. 

The atmospheric pressure needs to be specified because the gas law equation needs to work with absolute pressure, NOT gauge pressure. So, in the pv=nrt equation, the atmospheric pressure head is added to the gauged pressure head in the tank, to acheive the absolute pressure. 

Why is the HGL in my hydropneumatic tank sometimes very large and beyond the pump control range? 

Hydropneumatic tanks have a very short cycle time compared with large tanks. Therefore, when hydropneumatic tanks are used in a model, a very short hydraulic time step may be needed or the tank may overshoot its on and off levels. If this occurs, the hydraulic time step in the calculation options should be reduced. 

What does it mean when a node reports a negative pressure?

A negative pressure occurs when the hydraulic grade is below the physical elevation of a node. If WaterCAD/GEMS says the pressures will be negative, then in all likelyhood you will have problems. Assuming all data input has been checked, there are usually two general causes of negative pressure:

1. Trying to serve a customer at too high of an elevation. This will show up as low/negative pressure at any demand. You need to increase pump head or adjust pressure zone boundaries.

2. Some restriction in the system. This will show up as good pressure during low demand and poor pressure at high demand. You need to look at the model results and see if the pipes are too small causing excess head loss or the pumps are inadequate such that they are running far off to the right of the curve. You need to upsize the pipes or pumps accordingly.

You should also check your demands for errors. Since your demands are likely based on historic averages, a significant decrease in pressure may skew the results, since the demands would likely be decreased in that condition. You may consider using pressure dependent demands or flow emitters. You may also consider conducting a transient analysis using Bentley HAMMER, if the problem occurs at a transmission main.

Why do I get a negative pressure at a high point in my system? Shouldn't the pump add enough head to push the water over the hill?

By default, pumps only consider the boundary conditions (reservoirs and tank elevations) in your system. So, the pump will add enough head to lift the water to the downstream known hydraulic grade. It does not consider junction elevations inbetween. If you are using WaterCAD or WaterGEMS V8i, you should add an Air Valve element at the high point to properly model this situation. By placing an air valve at the high point, the pump sees the air valve elevation as its downstream boundary condition for instances in which pressure would have otherwise been negative at the high point. For any air valve that is expected to be open in this way, ensure that you select "false" for the "Treat air valve as junction?" attribute.

See Also

General WaterGEMS V8 FAQ

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

The SELECTseries 2 release of WaterCAD and WaterGEMSV8i includes many new features and improvements. This technote explores each change.

- Support for Newer Platforms
- Pipe Renewal Planner
- Pipe Break Analysis
- Improved Pump Curve Display
- Pump Combination Analysis
- Top-fill tanks with float valves
- EPANET calculation engine upgrade
- SCADAConnect Ease-of-use Improvements
- Projectwise Integration changes
- i-model support
- Seed File support
- DXF export layer control
- Symbology Definitions
- Microstation Integration Improvements
    - View associations
    - Tooltip customizations
    - Print preparation
    - GIS style
    - Multiple models
    - Detach and save-as Options
- More Flexible Date/Time Formatting
- Formula-based User Data Extensions
- Support for US Survey Feet
- Pressure loss result fields
- Performance increase for controls
- Multi-Select & Delete support for lists
- Selection Tool for User Notifications
- New Network Tracing Queries

Note: for details on new features in HAMMER V8i SELECTseries 2, see What's New in HAMMER V8i SELECTseries 2?

Support for Newer Platforms

WaterCAD and WaterGEMS now support the following platforms:

• AutoCAD 2010 and 2011 (32-bit version only)
• Microstation V8i SELECTseries 2 (08.11.07.443)
• ArcGIS 10 (WaterGEMS only)
• ProjectWise 08.11.07.XX

Pipe Renewal Planner

The Pipe Renewal Planner is a powerful new condition assessment tool, enabling you to score and rank existing water mains based on their adequacy in terms of a number of performance indicators called "aspects", which are not in the same units. The default aspects that the pipe renewal planner primarily considers are Pipe break history, capacity (fire flow) and criticality (demand shortfall when pipe is out of service). You can also consider any other aspect of the model, including calculated model results or user-entered field (such as installation year, zone, material, etc).

For a given aspect, each pipe is given a normalized score on a 0-100 scale. Each aspect is then given a weight, and an overall score is generated for each pipe.

The overall process for determining the "Pipe Score", which is the final result of this analysis, is:

1. Build model with sufficient information to calculate aspect of interest.
2. Optionally run capacity, criticality and pipe break analysis
3. Start Pipe Renewal Planner by selecting Analysis > Pipe Renewal Planner or picking the Pipe Renewal Planner button.
4. Pick the New button to create a new Pipe Renewal analysis.
5. Select aspects to be used and weights for each.
6. Set up scoring to convert raw score/property values into individual aspect scores.
7. Compute Pipe Renewal Pipe Scores.
8. Review results, using many standard methods such as color coding the plan view.

Note: Similar to Darwin Calibrator, Darwin Designer, Darwin Scheduler and Skelebrator, the Pipe Renewal Planner feature uses a separate license, which should show up in your license management tool. The Pipe Renewal Planner module is included with WaterGEMS. It is a separate cost for WaterCAD users.

Pipe Break Analysis

The Pipe Break Analysis tool is a new feature that allows you to import and analyze historical data on pipe breaks. The results of this analysis can be viewed on their own or used as part of the Pipe Renewal Planner tool to determine the overall condition score of a pipe. A projected break rate (breaks per year per mile) is calculated for each pipe, along with other results such as annual expected cost.

• A pipe break analysis should not be confused with a transient analysis. To check for maximum pressures during a transient or "surge" event, you will need to analyze the model with Bentley HAMMER.
• The number of breaks per pipe and duration of failure history can either be manually entered or imported from an external file (using the  button)
• When importing, each pipe break record needs to be associated with the pipe label/ID.

• The projected break rates can be converted to a "score" (on a 0-100 scale) in the "Predefined Aspect Options" tab of the Pipe Renewal Planner tool. These scores are then considered in the overall pipe score computed in the Pipe Renewal Planner tool.

The overall steps in conducting a pipe break analysis consists of:

1. Creating a model. (preferably an all-pipes model or a skeletonized model)
2. Setting up a scenario with a pipe break alternative.
3. Importing/creating pipe break history data within the Pipe Break tool.
4. Creating pipe break groups. (if group feature is used)
5. Setting other analysis options. (e.g. individual vs. group rates, projection period)
6. Run break projection.
7. View results.
8. Use results in Pipe Renewal Planner

For more detailed information, check the Running Pipe Break Analysis TechNote 

Improved Pump Curve Display

In previous versions, the pump curve viewer (right click on a pump and choose "pump curve") only displayed the head curve, for the current time step. The pump curve display has been improved in V8i SELECTseries 2 and you now have the ability to:

• Display the efficiency curve as well as the head curve.
• Display both efficiency and head curves for different times on the same axis.
• Display head curves at different relative speed factors for variable speed pumps.

Example 1: Current time with head and efficiency:

Example 2: head and efficiency at multiple times with different speeds:

Pump Combination Analysis

The SELECTseries 2 release of WaterCAD/GEMS V8i introduces a new element type called a pump station,  which is used in a new tool called Combination Pump Curves.

A pump station is a polygon element used to model multiple pumps that are in the same structure, serving the same pressure zone. It provides a graphical way to display the pumps associated with the station. A pump station is not a hydraulic element in that it is not directly used in a hydraulic analysis but rather it contains a list of pumps that are within the "station".

A pump station displays which pumps are in the station by dashed lines connecting the pumps with the station polygon centroid. A pump does not need to be inside the polygon to be a pump assigned to the station and pumps inside the polygon still need to be assigned to the station. Select the pump station from the "Pump Station" attribute of each individual pump.

Once the pump station has been established, you can perform a pump combination analysis, either by right clicking the pump station and choosing "combination pump curve" or by going to Analysis > Combination Pump Curves. Multiple combination pump curves can be created and saved, similar to the system head curve manager.

Combination Pump Curves allow you to view the performance of multiple pumps running together in parallel in a pump station. The system head curve can optionally be displayed, at multiple times. The example below shows three different combinations for two time steps (system head curves).

The "active?" column allows you to choose from all possible combinations of pumps (which ones are on or off). The "ID" is used to identify the particular combination in the legend. The number in the cell indicates the number of pumps of that pump definition that are running for the combination corresponding to that row. If there is a zero in a cell, the pump is off for that combination.

For more information on this topic please click here

Top-fill tanks with float valves

If the tank is a top filled tank (which may refer to a side inflow tank above the bottom but below the top), you can now model this directly in the properties of the tank node. Select "true" for the "Tank Fills From Top?" property and set the invert level (relative to the base) of the inflow pipe at its highest point. Water will not flow into the tank through that pipe unless the hydraulic grade is above that elevation.

If the inlet valve throttles the flow as it nears full, you can also now directly model that in the tank node, by selecting "true" for" Inlet Valve throttles?". You must then enter the discharge coefficient for the valve when it is fully open, the level at which the valve begins to close and the level at which it is fully closed.

EPANET calculation engine upgrade

The SELECTseries 2 release of WaterCAD/GEMS V8i includes an upgraded version of the EPANET hydraulic calculation engine: 2.00.12. This version includes enhancements to control valve convergence (such as PRVs in parallel) and water quality computational changes. Several new calculation options are available to facilitate the convergence enhancements.

You also now have control over which version of the calculation engine to use, mostly for compatibility reasons:

• WaterGEMS 2.00.12 - Computation engine based on EPANET 2.00.12 with Bentley's own enhancements and features.
• WaterGEMS 2.00.10 - Computation engine based on EPANET 2.00.10 with Bentley's own enhancements and features.
• EPANET 2.00.12 - Computational engine based on EPANET 2.00.12 including any Bentley enhancements and features that do not change hydraulic results compared to EPANET, for models that are able to be completely represented in EPANET.
• EPANET 2.00.10 - Computational engine based on EPANET 2.00.12 including any Bentley enhancements and features that do not change hydraulic results compared to EPANET, for models that are able to be completely represented in EPANET.

SCADAConnect Ease-of-use Improvements

The SCADAConnect module now has the following improvements:

• Connection Manager, for easier setup of connection strings
• Improved user interface
• Improved documentation
• Ability to populate user data extension fields
• "Load Initial Settings" tool for creating scenario/alternative
• 25-signal license is now included with WaterGEMS

Projectwise Integration Enhancements

In this release, the integration with Projectwise has been enhanced:

• Enables ProjectWise collaboration
• Save/Open all files to/from ProjectWise
• Supports ProjectWise Captive Environment
• Supports Single Sign-On and Auto-Login
• Supports Document Creation Wizards

i-model Support

With the SELECTseries 2 release of WaterCAD and WaterGEMS V8i, you can now publish an i-model. An i-model is an immutable container for rich multi-discipline information published from known sources in a known state at a known time. Basically it is a portable, read-only copy of a model file that can be viewed by users that do not have WaterCAD/GEMS. The topology as well as the attributes and results (for a particular timestep) can be viewed in MicroStation, ProjectWise Navigator and Bentley View. Since Bentley View is free, i-models provide a way for anyone to easily view data and results for a WaterCAD/GEMS model file.

Under File > Export, you will have a "publish i-model" option, which requires the i-model publishing engine (downloadable from selectservices.bentley.com). The i-model publishing engine shows as a prerequisite on the download page for WaterCAD/GEMS, but is only necessary if you intend to publish i-models. If you have no need to publish i-models, you do not need to download and install this optional component.

Seed File Support

Seed files allow you to save project settings and data as a template (the seed file has a .wgs extension). You can then reuse these settings/data while creating new projects using the data from the previously saved seed file.

DXF export layer control

When exporting the plan view of a drawing to a DXF file, different elements can be placed on different layers.

• For nodes, you can can enter a custom label for the layer.
• For pipes, you can choose to generate layers for each pipe diameter, with control over the prefix and suffix.

Symbology Definitions

You will now have a dropdown at the top of the Element Symbology manager, which allows you to configure which symbology should be applied. For example, you could have one symbology definition for steady state with certain annotations and color coding enabled, then another one for EPS, with different annotations and color coding enabled.

• Click the ellipsis button next to the dropdown at the top of the Element Symbology manager to create new symbology definitions.
• All color coding and annotations that you create will always show up. Symbology definitions simply keep track of the status of the check boxes, for annotations, color codings are the element type itself.
• Create a new symbology definition, choose it from the dropdown, then check or uncheck the desired items.

Microstation Integration Improvements

A number of improvements have been added to the Microstation Environment:

View Associations

When working in the MicroStation integrated mode, it is now possible to associate scenarios and symbology definitions with MicroStation Views. This basically lets you see different scenarios and/or symbology definitions (color coding/annotation at the same time, by opening multiple MicroStation Views.

A "mode" button is available for both Element Symbology and Scenarios:

• Synchronized mode: This basically means that the scenario (or symbology definition) will be the same for all views. Switching the scenario or symbology definition will cause it to change for all views. Use this mode for scenarios if you want all views to always show the same scenario. Use this mode for symbology if you want all views to use the same symbology definition (arrangement of symbology). 
• Independent mode: This basically means that the scenario (or symbology definition) can be different for all views. Switching the scenario or symbology definition will cause it to only be switched in the active View. Use this mode for scenarios if you want a view to always show the scenario that you selected when that view was active. Use this mode for symbology if you want a view to always use the symbology definition that you selected when that view was active.

Example:

• View 1 shows symbology for data entry such as elevations and pipe material
• View 2 shows the same scenario but with symbology to review results such as pressure
• View 3 shows a close up of a subdivision in a different scenario
• View 4 shows annotated fire flow results for an automated fire flow scenario

Tooltip Customizations

While using the Microstation integrated mode, the new tooltip customization feature allows you to define custom text to appear when hovering the mouse over an element in the drawing. You can enter static text and/or dynamic annotations, similar to element symbology annotations. This can be a convenient alternative or supplement to annotations, as you can quickly view data just for the element you point to.

Note: be sure to right click on the tooltip customization and choose "make active".

Multiple Model Support

A single dgn file can now reference multiple WaterCAD/GEMS models, by using the MicroStation Models feature. Simply attach a new model to the dgn, then attach the WaterCAD/GEMS model. Here is an example workflow:

• In the Models window, create a new model.
• Click the view attributes button at the top-left corner of a view, then select the desired model.
• With a certain view active, go to the WaterGEMS menu and choose Project > add existing project (or add new project if you're just starting a model.)
• Make the other view active and repeat the above step.

Print Preparation

Print Preparation is a special tool that was not readily available in previous versions. It is now included with the installation of WaterCAD/GEMS, making it easier for you to print your model when using the Microstation integrated mode. It can be accessed from the bottom of the Tasks list:

Print preparation is essentially a printing wizard; first you select a template, then follow the prompts, selecting the area of the drawing and rotation for the main viewport and detail views. Several templates are included with WaterCAD/GEMS: ANSI, ARCH and ISO:

GIS style Display

You can now choose between CAD (zoom dependent) or GIS (zoom independent) drawing style when working in MicroStation. With GIS style, symbol and text sizes stay the same, regardless of your zoom level.

• Select from the Drawing Style button at the top of the Element Symbology manager.
• Can be changed on a per-element-type basis, by double clicking on the desired element in the element symbology list, then editing the "display style" field in the property grid.

Detach and save-as Options

In this release, you can now detach a WaterCAD/GEMS model from the dgn and save it to a new location.

• To detach the model from the drawing, go to WaterGEMS > Project > Detach. When opening the dgn, the model will now no longer open.
• To save a model to a new location, go to WaterGEMS > Project > Save Attached As, then pick the new location. In previous versions, the model files were not necessarily stored in the same location as the dgn, so relocating the model was not as easy.

More Flexible Date/Time Formatting

In previous versions, time was often displayed in a fixed way, and in some cases was not consistent. for example, the calculation summary displayed as 03:00:00 whereas data tables displayed as 3.00. In V8i SELECTseries 2, you can now customize the time format.

• This applies to numerous different things, such as graphs, tabular data, the Time Browser, etc.
• When looking at a time field, right click and choose "units and formatting". You can now select from an array of time formats.
• For graphs, right click on the time axis and choose "time properties" to bring this up.

• The "EPS Results Browser" is now called the "Time Browser". Instead of just showing clock time, it now shows decimal clock time along with a second column that can be customized, like mentioned above.

Formula-based User Data Extensions

In the past, a user data extension always contained static, user-entered information. Now, you can create a user data extension whose value is calculated based on other existing fields. For example, you can create a field whose value is equal to the square root of the difference between one input field and another user data extension. The possibilities are endless. In the below example, a field has been created for pipe elevation, whose value is equal to the junction ground elevation minus 5 feet.

• User data extensions are accessed from Tools > User Data Extensions.
• Choose “Real (Formula)” for the “data type”.
• Be sure to choose the correct dimension, unit and numeric formatter. For example the result shown in the above “Pipe Elev” example user data extension is a length dimension, with depth as the formatter. This means that this field will use the correct units (feet, a unit of length) and the same format settings (decimal precision, etc) as other elevation fields. This way, it can be graphed on the same axis as other depth fields.
• In the formula editor, double click attributes at the top to populate the correct field name at the bottom. Right click to change the unit as necessary.
• Many math functions (such as square root, absolute value, etc) are available in the formula editor window and you can also use IF/than/else statements.

Support for US Survey Feet

You can now select US Survey feet as a length unit.

• Very close, but not exactly the same as international feet
• One International Foot = 0.3048 meters
• One US Survey Foot =  0.3048006 meters

Pressure loss result fields

Pressure Loss and Pressure Loss Gradient have been added as standard result fields.

Performance increase for controls

Performance has been improved when working in the Control manager (Components > Controls). Meaning, navigation through the Control user interface should be faster, especially for larger models with many controls.

Multi-Select & Delete support for lists

You can now use the CTRL (control) and Shift keys to select multiple items in lists. For example under Components > Controls > Conditions, you can click one condition, hold the control key and select several other conditions, then press the delete key to delete them all at once. This feature applies to:

• Profiles
• Graphs
• Contours
• Selection Sets
• Zones
• Pressure Dependent Demand Functions
• Unit Demands
• Pump Definitions
• Minor Loss Coefficients
• GPV Headloss Curves
• Constituents
• Valve Characteristics
• Controls (Controls, Conditions, Actions and Control Sets tabs)

Selection Tool for User Notifications

• Use the new “select all elements with message ID...” button to select all elements that have the same message type as the selected notification.
• In addition to viewing the location of these elements in the drawing pane (highlighted in red), you can also create a selection set or filter a flextable.

New Network Tracing Queries

Three new network tracing queries have been added:

• Find path to nearest element of specified type
• Find path to nearest upstream element of specified type
• Find path to nearest downstream element of specified type

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Water and Wastewater Forum

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Overview

The SELECTSeries 3 release of WaterGEMS and WaterCAD include many new features and improvements. This technote briefly explores each change.

-Support for 64-bit Operating Systems and Newer Platforms

-Water Quality Batch Run

-Pump Station Energy Costs

-Unit Carbon Emissions calculations in Energy Costs

-New Skelebrator Operation (Inline Isolation Valve Replacement)

-Scheduler Improvements

-Pump Station Results in the Property Grid

-Find Pressure Zone from Element

Support for Newer Platforms

WaterGEMS and WaterCAD V8i SELECTSeries 3 now support the following platforms:

• AutoCAD 2012 (32-bit and 64-bit) and AutoCAD 2011 (certified for 32-bit only)
• Microstation V8i SELECTseries 2 (08.11.07.443)
• ArcGIS 10 and ArcGIS 9.3.1 SP2
• ProjectWise 08.11.07.XXX

WaterGEMS and WaterCAD can now be installed as 64-bit applications, allowing for the programs to fully integrate with 64-bit versions of AutoCAD. During installation on a 64-bit operating system, the program will attempt to install both the 32-bit and 64-bit versions of the product. The 32-bit version can be used in Standalone, MicroStation and ArcGIS (for WaterGEMS) platforms. The 64-bit version can be used in Standalone and AutoCAD platforms.

Please note that the 64-bit versions of these products are not compatible with the 32-bit version of Microsoft Office, due a compatibility issue with the Microsoft Access Database Engine component.

Water Quality Batch Run

The Water Quality Batch Run feature allows you to perform a combined Trace or Constituent analysis. You can then use the provided reporting tools to graph the combined effects of each type of analysis on various parts of your system, or to review system-wide tabular statistics reports.

To create a new analysis, highlight either Trace or Constituent from the list on the left and click the New icon at the top. For each type of water quality analysis, you will need to choose a representative scenario. This is the scenario that the analysis will be conducted on. Depending on whether you choose Trace or Constituent, the left part of the dialog will look different.

For a Trace analysis, you will need to select the element or elements in the drawing on which the Trace analysis will be conducted. This is done by selecting the “Select from Drawing” below the Representative Scenario pulldown.

For the Constituent analysis, you will need to choose the Constituent alternative that will be used during the analysis. This is done by selecting the “Select Alternatives to Analyze” icon. Note that the Constituent alternative must already be created and contain the constituent source and data.

After the data is selected, highlight the type of analysis and click the compute button. You can view the results as a table or as a graph.

Pump Station Energy Cost 

The ability to calculate the energy costs for operating a pump station, rather than just the individual pumps, has been included in WaterGEMS and WaterCAD V8i SELECTSeries 3. Please review the Carbon Emission and Energy Cost TechNote for more information.

Unit Carbon Emissions Calculations

 This is a new feature added to the existing Energy Cost analysis. After entering a carbon dioxide emission factor, you can use the Energy Cost tool to help determine the total carbon emissions produced during the pump operation. Please review the Carbon Emission and Energy Cost TechNote for more information.

New Skelebrator Operation (Inline Isolation Valve Replacement)

In building a model from an external source such as a GIS, the GIS may be set up such that isolation valves split a pipe into two separate pipes. These isolation valves are usually imported into WaterGEMS as throttling control valves (TCV) or general purpose valves (GPV) with ModelBuilder. This is due to the fact that WaterGEMS isolation valves are attached to pipes and do not split them.

While models that split pipes with a TCV or GPV will run, they are usually about twice as large as one that models isolation valves as attached to a single pipe and not splitting pipes. In Skelebrator, it is possible to automatically convert all or a selection of valves into WaterGEMS isolation valves, and merge the pipes on either side of the valve into a single pipe element. The pipes that are merged are treated the same as they are under the series pipe merging option that already existed in Skelebrator, except that the isolation valve element is maintained at its original location and can be used for segmentation.

Darwin Scheduler Improvements

Darwin Scheduler in an earlier release of WaterGEMS and WaterCAD. This tool uses a genetic algorithm to optimize pumps and pump stations in a WaterGEMS model. Previous versions of Darwin Scheduler optimized only the individual pumps in a model.

Darwin Scheduler has been updated to include the optimization of pump stations. This is particularly useful in cases where a pump station contains a number of pumps that operate on the same pump curves. A tab was added to Darwin Scheduler to allow a user to select and optimize pump stations (Pump Stations to Optimize). This allows for Scheduler to simply determine the number of pumps that should be running, rather than which pumps are running. This allows Darwin Scheduler to test more possible solutions and allows for improved results. For this reason, it is generally recommended that the optimization is conducted on pump stations instead of individual pumps when possible.

Please review the Darwin Scheduler TechNote for more information on using this tool. Note that Darwin Scheduler is included with WaterGEMS and available as an add-on to a WaterCAD license.

Pump Station Results in the Property Grid

In earlier releases of WaterGEMS and WaterCAD, the pump station element properties were limited to the activate topology setting and which pumps were associated with it. WaterGEMS and WaterCAD V8i SELECTSeries 3 introduce a more robust property grid.

The property grid now displays detailed results fields for the Energy Cost Summary and Energy Costs for the pump station. You can review these fields by double-clicking the pump station element. Note that the results will be listed as N/A until an energy cost analysis is conducted on the model. 

Find Pressure Zone for Element

The Pressure Zone manager was introduced in an earlier release of WaterGEMS and WaterCAD. This tools allows you to determine which elements are in a given pressure zone in a model. After creating the zones for your model based on the boundary elements and selecting a representative element, you can compute the Pressure Zone study to find how many elements are in a given pressure zone. This data can also be exported out to your Physical alternative.

WaterGEMS and WaterCAD V8i SELECTSeries 3 introduced a “Find Pressure Zone for Element” function that allows you to identify which pressure zone a given element is found. After computing the Pressure Zone study, click the “Find Pressure Zone for Element” icon in the Pressure Zone manager under the Zone Results tab. This opens the Select tool bar. Choose the element in the drawing. The Pressure Zone manager will return with one of the pressure zones highlight, indicating the pressure zone that the element is located in.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Water and Wastewater Forum

Bentley Technical Support KnowledgeBase

Bentley LEARN Server</

Hello,

This is appears to be occurring because the default design constraints for certain elements are being violated. I will note that I tested this in each of the last three versions of SewerCAD (including yours). In each, the same results were found.

The design solver will try to find the best solution within the contraints applied, but there are a set of design priorities that must be followed as well. For instance, the design solver will not allow for a downstream conduit to be smaller in diameter than an upstream conduit. So even if an optimal design would be to have a smaller conduit in place, if the conduit directly upstream was larger than that design option, the smaller size could not be used. In other words, the design conduit must be the same size or larger than the upstream conduit. There are a number of these design priorities, which can be found below. The designed size of the conduit must be meet these in order to be used. Some priorities are given greater weight than others, which is high some design priorities (like velocity constraint) can be violoated at times.

When using a simple part-full design of 75%, conduits CO-1 through CO-7 do not meet the minimum velocity constraint. In other words, the velocity in the conduit is lower than the minimum velocity design constraint that you have entered. In some of these, like CO-1, a smaller size cannot be chosen because the smallest size is already being used. Other conduits may see other design priorities given a higher priority than the velocity constraint being violated if a smaller size is used, such as design discharge or slope constraints. For instance, if CO-7 were smaller, the velocity constraint would not be violated. However, CO-6 is would then be larger *and* the design discharge constraint would be violoated. Both of these are higher priority design priorities than the velocity constraint, and therefore CO-7 cannot be designed at a smaller diameter.

When you use the table part-full design, where some of the conduits have a lower part-full percentage, some other constraints are also not met. The same design priorities are used in this case, and must be satisfied before a possible conduit size can be used. As an example, for CO-6 violates the velocity constraint. CO-5 is smaller than CO-6, so a smaller size could be used. However, if the smaller size is selected, the design discharge would be above capacity. Since the design discharge constraint is a higher priority, the smaller size conduit cannot be used.

The design of the conduits and manholes are all interconnected, so you will want to make sure that you review not just the conduit receiving the user notification, but also to look at the conduits and nodes around it, keeping in mind that there may be reasons not only why the conduit in question is not allowed a different diameter, but why those around it might not as well. You may also want to review the settings in the Default Design Constraints to assure that the correct data is entered for your system. In addition, I would review the information below, pertaining to the design priorities used in SewerCAD's design solver. Higher priority items are at the top, meaning they are given greater consideration in the design of a system than those with a lower priority.

Please let us know if you have any additional questions on this issue.

---------------

Design Priorities

A Designed Pipe Should Fit within Adjacent Existing Structures

If a pipe connects to an existing structure, the pipe rise should be completely within the existing structure. The only time this may be violated is if there are no available section sizes that would not violate that condition (i.e., the existing structure height is so small that all available pipes have rises too big). In this very unlikely condition, the smallest available section size will be selected, with the invert elevation placed at the bottom of the structure.

A Designed Pipe Should Not Have a Crown Above an Adjacent Designed Structure

Where pipe inverts are fixed, it is possible that the required section size would cause the pipe crown to be higher than the top elevation of an adjacent designed structure. If all available pipe section rises are greater than the depth of the pipe invert, the smallest pipe size will be chosen.

Note:  This situation will only be encountered in situations where the structure's top elevation is set equal to the ground elevation - otherwise, the structure will be designed with a higher top elevation.

Pipe Capacity Should Be Greater Than the Discharge

If the pipe is not limited by adjacent structures, the pipe should be sized such that the design capacity is greater than the calculated discharge in the pipe. The design capacity may be based on one or more pipes, flowing full or part-full, depending on user-set design options. If site restrictions or available section limitations result in a situation where no sections meet the required capacity, the largest available size and number of barrels will be chosen.

Downstream Pipes Should Be at Least as Large as Upstream Pipes

Designs typically avoid sizing downstream pipes smaller than upstream pipes, regardless of differing slope and velocity requirements. One of the primary reasons for this is debris that passes through the upstream pipe could become caught in the connecting structure, clogging the sewer.

Pipe Matching Criteria Downstream Should Be Met

Whenever possible, the designed pipe should have its downstream invert set such that the pipe meets the matching criteria, such as matching inverts or crowns. Note that because of higher design priorities, such as the pipe fitting within existing structures, the matching criteria may not always be met.

Minimum Cover Constraint Should Be Met

Pipe inverts should be set such that the upstream and downstream crowns of the pipe are below the ground elevation by at least the amount of the minimum cover. Note that higher design priorities, such as existing structure locations and matching criteria, may prevent the minimum cover constraint from being met.

Pipe Matching Criteria Upstream Should Be Met

The upstream invert of the designed pipe should be set to meet the matching criteria of the upstream structure. Higher design priorities, such as minimum cover constraints, may result in a pipe that does not match upstream as desired.

Maximum Slope Constraint Should Be Met

Wherever possible, the designed pipe should not exceed the desired maximum slope. In some situations, elevation differences across the system may result in a case where a drop structure can be used to offset pipes. This is used instead of a pipe that is too steep, or instead of upstream piping that would require much more excavation. Note that the maximum slope constraint may be violated if higher priority design considerations, such as existing structure location or pipe matching criteria, governs.

Other Constraints and Considerations

There are many degrees of freedom when designing a piping system. Several constraints that are not mentioned above, such as minimum velocity constraints and minimum slope constraints, may also result in adjustments to the designed pipe. Other constraints may be too limiting, such as maximum cover constraint and maximum velocity, resulting in designed pipes that could violate too many other constraints.

This wide range of choices and priorities emphasizes the need for careful review of any automated design by a professional. It is not always possible to meet every desired condition, so it is very much the responsibility of the engineer to make final judgments and decisions regarding the best design for the client.

If you have any other questions or concerns, please let us know.

Regards,

Scott Kampa

Bentley Technical Support

Fellow users,

I am modeling a complex sanitary sewer system in SewerGems. The primary problem in the system has been inflow and infiltration, so I am modeling catchments for each sewershed with RTK tables assigned to them. I have set up several storm events which are assigned to their respective catchments. 

The problem I am experiencing is as follows: I want the storm events to start later in the simulation (i.e. not at 0:00:00). I have set up my storm events as Time-Depth series with a duration of 120 hours, and have the first 24 hours at 0 depth. The storm event lasts from 24:00 to 36:00, then 36:00-120:00 is once again at 0 depth. However, when I run my model, I am still seeing the storm occurring at 0:00:00. Is there any way around this? Am I missing an option I should be setting, or is this a bug?

Details:

Sanitary SewerGems v8i SelectSeries 3

Version 08.11.03.77 (64-bit)

GVF-Convex (SewerCAD) Solver

Thank you for your help.

Hi,

Let’s try something like this as I didn’t find a clear way of modeling what you are trying. (Based on your description, network downstream of the booster pump will receive water from that pump-station so, I am curious, why you need to trace d/s of booster pump? The source of water is already known, right?)

I assume your network is something like this:
Source A ---->---->----Network---->----Booster Pump---->----> Network

Instead of setting the Concentration (Base) to 0, let’s set it to quite higher value…

I am using Example4 here.
R1 ---->---->----Network---->----PU8 and PU9---->----> Network
1) Create a scenario with a calculation options set to Constituent for Calculation Type.
2) Make sure the Base Constituent Alternative is using NONE constituent
3) Make this scenario active.
4) R1: Is Constituent Source = True, Concentration (Initial) = Concentration (Base) = 100 mg/L
5) J87: (d/s of PU8,PU9): Is Constituent Source = True, Concentration (Initial) = Concentration (Base) = 500 mg/L, Constituent Source Type = Setpoint Booster.
6) Run the model and observe the results.
 

Most of the time:
Anything below 100 mg/L is from R1 source and anything below 500mg/L is from Booster Pump (If you have too little difference in source contraction, it might difficult to separate the source). 

Above is my initial approach and I could be heading wrong :)

 Thanks,

Hi John,

In this case, it looks like some of your Catch Basins are probably set to Full Capture, Percent Capture, or one of the other Inlet Type options under the Catch Basin Properties. Make sure all Catch Basins are set to Catalog Inlet types in the Catch Basin Properties. GEOPAK export requires all Catch Basins to be of the Catalog Inlet type.

Regards,

Dan

What is the elevation of that node? If it's 14m then here's the math:

9.9 + 14 = 23.9

(It's good to create a new Forum post with a descriptive topic, if you have a different question so that it may help others)

Hi Bruce,

It sounds like you have a mechanical problem and if so, you _may_ not hear any recommendations. What about contacting the manufacturer?

If it's a hydraulic modeling issue then please let us know some more details.

Hi Giancarlo,

Not all of us here are familiar with EPANET programming side so if you could let us know what you are trying to get from WO API, we might be able to help you.

Honestly, I am not sure what ENgetlinkvalue does but I am guessing you are interested in getting some link attributes?

Mark,

Thanks again for your advice.

After removing the junction with negative flow and changing the initial setting of FCV to closed, FCV started to open and closed at longer cycle (> 24 hurs), instead of open and close every several hours.  First, I thought FCV started to close at right time between midnight and 6 am most of the time. However, when I adjusted other settings such as HSP pump controls and FCV flow rate, FCV does not close at mid night any more.

By trying different sets of controls, I found the followings:

1. FCV is controled by two control settings (The Clock Time does not seem to have any effect):

    - IF Clock Time  > 6:00 AM  And Clock Time  < 11:59 PM  And R-2MG Hydraulic Grade < 829.00 ft

      THEN FCV-4 FCV Setting = 2,500 gpm

    - IF R-2MG Hydraulic Grade >= 832.99 ft THEN FCV-4 FCV Status = Closed

2. The following control to close FCV does not seem to have any effect.

   - IF Clock Time  >= 11:59 PM  And Clock Time  <= 6:00 AM  THEN FCV-4 FCV Status = Closed

3. FCV pattern which was set according to your last advice also does not seem to have any effect.

With your advice, I now can close FCV according to its elevation, but not according to time.

I'd appreciate your further guidance on how to close the FCV according to time.

Thanks.

Yoko

The following TechNotes and FAQs are provided as a reference by Bentley's Technical Support Group.

Licensing

• Pre-XM Licensing of Bentley Haestad Products
• XM Licensing Of Bentley Haestad Products
• General SentinelLM Server FAQ
• XM License Configuration

Haestad Product Compatibility Chart 

• Compatibility Chart

Bentley SewerCAD V8 XM and V8i

• Modeling Force Mains With Air Valves
• Importing Loading Information Using Modelbuilder
• Loadbuilder - Flow Monitoring Distribution
• Creating User-Defined Profile Settings
• Using Fit To Page Printing In The Standalone Platform
• Scenario and Alternative Management
• Active Topology Management
• Creating formula-based User Data Extensions
• What's new in SewerCAD V8i SELECTseries 2?
• What's new in SewerCAD V8i SELECTseries 3?
• Importing a CAD Drawing Using Modelbuilder
• General SewerCAD FAQ

Bentley StormCAD V8i 

• Creating User-Defined Profile Settings
• Using Fit To Page Printing In The Standalone Platform
• Transferring Custom Inlets Catalogs,Storm Data, Conduit Catalogs, or Flow-Headloss Curves from One Computer to Another
• Scenario and Alternative Management
• Active Topology Management
• Creating formula-based User Data Extensions
• Importing a CAD Drawing Using Modelbuilder
• What's new in StormCAD V8i SELECTseries 2?
• General StormCAD FAQ
• What's new in StormCAD V8i SELECTseries 3?

Bentley HAMMER V8 XM

• Modeling a Pump Start-up Transient Event
• Using Fit To Page Printing In The Standalone Platform
• General HAMMER V8 XM FAQ

Bentley HAMMER V8i

• Modeling a Pump Start-up Transient Event
• Modeling Reference - Hydropneumatic Tanks
• Modeling Reference - Air Valves
• Modeling Reference - Surge Valves
• Modeling Reference - Valves Of Various Types
• Modeling Reference - Valve With Linear Area Change
• Modeling Reference - Discharge To Atmosphere
• Modeling Reference - Check Valves
• Using Turbines in Bentley HAMMER
• Modeling existing valves as Throttle Control Valves in HAMMER
• Using Modulating PRVs
• Using Fit To Page Printing In The Standalone Platform
• Modeling An Initially Partially Closed Valve
• Scenario and Alternative Management
• Active Topology Management
• Creating formula-based User Data Extensions
• Importing a CAD Drawing Using Modelbuilder
• General HAMMER V8i FAQ
• Protective Equipment FAQ
• What's new in HAMMER V8i SELECTseries 2?
• What's new in HAMMER V8i SELECTseries 3?
• What's new in HAMMER V8i SELECTseries 4?

Bentley Pondpack V8i

• Scenario and Alternative Management
• Active Topology Management
• Using PondMaker
• What's New in Pondpack V8i?
• Entering Storage Chamber Information
• [[Understanding the Modified Rational Method]]

Bentley SewerGEMS V8i

• Loadbuilder - Flow Monitoring Distribution
• Using Fit To Page Printing In The Standalone Platform
• Creating User-Defined Profile Settings
• Scenario and Alternative Management
• Active Topology Management
• Creating formula-based User Data Extensions
• What's new in SewerGEMS V8i SELECTseries 2?
• Importing a CAD Drawing Using Modelbuilder
• Running a Long Term Continuous Simulation
• General SewerGEMS For ArcGIS FAQ
• What's New with SewerGEMS V8i SELECTseries 3?
• General SewerGEMS FAQ
• [[Understanding the Modified Rational Method]]

Bentley CivilStorm V8i

• Scenario and Alternative Management
• Active Topology Management
• Creating formula-based User Data Extensions
• Running a Long Term Continuous Simulation
• What's new in CivilStorm V8i SELECTseries 2?
• Importing a CAD Drawing Using Modelbuilder
• What's New with CivilStorm V8i SELECTseries 3?
• [[Understanding the Modified Rational Method]]

Bentley WaterGEMS V8 XM

• Importing A CAD Drawing In Bentley WaterGEMS
• Importing Demands From A Spreadsheet
• Understanding Automated Fire Flow Results
• Adding Multiple Minor Losses To A Pipe
• Using Fit To Page Printing In The Standalone Platform
• Scenario and Alternative Management
• Active Topology Management
• General WaterGEMS V8 FAQ
• General WaterGEMS V8 Modeling FAQ
• General WaterGEMS for ArcGIS FAQ
• WaterGEMS V8 Automated Fire Flow FAQ

Bentley WaterGEMS V8i

• Active Topology Management
• Importing A CAD Drawing In Bentley WaterGEMS
• Importing Demands From A Spreadsheet
• Understanding Automated Fire Flow Results
• Creating controls, conditions, actions and controls sets
• Adding Multiple Minor Losses To A Pipe
• Importing Time Series Data Using ModelBuilder
• Modeling Air Valves At High Points
• Building A Model Using Model Builder
• Updating A Model Using Model Builder
• Updating Source File Using Model Builder
• Using Darwin Calibrator
• Using Darwin Designer
• Using Darwin Scheduler
• Setting Up Pressure Dependent Demand
• Using Fit To Page Printing In The Standalone Platform
• Using The Network Navigator
• Running a Criticality Analysis
• Using Pipe Renewal Planner
• Running Pipe Break Analysis
• Scenario and Alternative Management
• General WaterGEMS V8 FAQ
• Opening old models in WaterCAD/GEMS V8 XM or V8i
• Submodel Importing and Exporting
• Pump Station and Pump Combination Curves
• ProjectWise Integration
• Setting Boolean (True/False) Fields using Model Builder
• Engine Compatibility Modes and Calculation Options
• Creating formula-based User Data Extensions
• Carbon Emission Analysis and Energy Cost Analysis
• Energy Cost Analysis WaterGEMS V8i SELECTseries 4
• SCADAConnect using Citect Server as data source
• WaterGEMS V8 Modeling FAQ
• WaterGEMS For ArcGIS FAQ
• WaterGEMS V8 Automated Fire Flow FAQ
• What's new in WaterCAD and WaterGEMS V8i SELECTseries 2?
• What's new in WaterGEMS and WaterCAD V8i SELECTseries 3?
• What's new in WaterGEMS and WaterCAD V8i SELECTseries 4?

Bentley WaterGEMS 3.0

• Setting Up An Automated Fire Flow Analysis In WaterCAD 7.0 Or WaterGEMS 3.0

• General WaterCAD 7.0 Or WaterGEMS 3.0 FAQ

See Also

WaterCAD product information

WaterGEMS product information

Product TechNotes and FAQs

External Links

Haestad Methods Water Solutions on Bentley Website

Haestad Solutions eSeminars

WaterCAD Trailer Video

WaterGEMS Trailer Video

WaterCAD User Guide

WaterGEMS User Guide

Advanced Water Distribution Modeling and Management online textbook

Support page on Bentley website

Bentley technical support KnowledgeBase

Overview

This Technote will describe in detail the process for running an Energy Cost Analysis in WaterCAD v8i and WaterGEMS v8i (SELECTSeries 4). It is meant to provide a more detailed description of running the Energy Cost Analyses than the Help Documentation.

Background

There are two levels at which energy costs can be analyzed in WaterGEMS. The tool called "Scenario Energy Cost" calculates energy use and cost for a single scenario while "Energy Management" uses the results of multiple Energy Cost scenarios to determine energy costs at a higher level of aggregation to determine the energy cost for pump stations (not just pump-by-pump) for multiple scenarios that can occur over a billing period and determine economic costs such as net present worth of pumping energy.

The Scenario Energy Cost analysis determines the energy cost by pump for all pumps selected by the user. Pricing for energy cost is set up in the Pricing button in energy costing. Price functions are assigned to individual pumps in energy costing.

For users interested in a more complete energy analysis, running a single scenario may not be sufficient as block rate charges must be determined based on energy use over a complete billing cycle which may contain low, average and high water use periods which should be modeled as separate scenarios. In addition, the scenario corresponding to the setting of a peak demand charge is usually not an average day but some kind of peak condition that should be modeled in a separate scenario. In order to deal with the complexities of block rates, multiple scenarios, aggregation of pumps within a station, and performing present worth calculation, the user needs to use the Energy Management analysis. Such calculations are usually required because of complex tariffs for electric power.

An important concept in energy management analysis is that of a "Power meter". A Power Meter is the basic unit that is billed by an electric utility. A Power Meter usually corresponds to a pump station. However, in WaterGEMS, a pump station is a collection of pumps serving a single pressure zone. Therefore, if a pump station building has a single
electric service but has a set of Low, Medium and High service pumps, for WaterGEMS hydraulic calculations, it is three Pump Station elements but for energy management, it corresponds to a single Power Meter. The figure below shows how a single power meter can include multiple pumps and pump stations in a single building.

Because there may be other energy uses at the pump station besides pumping, the user can specify non-pumping energy costs to account four uses such as lighting, HVAC, control systems, chemical feed equipment, etc. These costs are added in on a Power Meter basis. There may also be charges on the power bill that are not associated with individual pumping operations such as taxes, discounts, lump sum surcharges, etc. These can be added in to the overall cost and are referred to as "other costs".

The usual work flow for using the energy cost and energy management analyses may be followed as shown below:

• Develop EPS scenarios to be used in energy cost.
• Run scenarios.
• Start scenario energy cost analysis.
• Create price functions and optional carbon emission factors.
• Assign price functions to pumps.
• Run energy cost for each scenario of interest.
• If more thorough analysis is desired, close scenario energy cost analysis and start energy management.
• Create new energy management study.
• Identify which pump stations/pumps are associated with each power meter.
• Specify the mix of scenarios to be analyzed.
• Identify interest rate and number of periods if present worth calculations needed.
• Compute study.
• Review results and rerun or create new studies.

In the next section we will go through a detailed step by step guide of how to use the Energy Management and Scenario Energy Cost tools.

<h2>Energy Management</h2>

<h2>Energy Pricing</h2>

<h2>Power Meters</h2>

Scenario Energy Cost Analysis

The Scenario Energy Cost tool can be opened by going to Analysis > Scenario Energy Cost, or by selecting the Scenario Energy Cost icon in the toolbar.

This will open the Energy Cost manager.

On the left side of the manager, it will display the current scenario. If you wish to analyze a different scenario, you can choose it from the Scenario pulldown. When you change the scenario, you will also see the scenario change on the left window as well.

Note: the scenario used must be an EPS run.

The right side of the manager is where you will set up the energy cost analysis and view the results. At the top are some general results fields. Below that is a table with the elements that are included in the energy cost analysis. In the table, you can specify which elements will be included in the analysis and the energy pricing.

After selecting the scenario you will be analyzing, you will need to set up the energy pricing. To do this, click in a cell in the Energy Pricing column and click the ellipsis ("...") button. This will open the Energy Pricing manager.

The left side of this manager will include any energy pricing definitions. To create a new definition, click the New icon in the upper left. On the right side of the manager is where the data is entered. The energy pricing data itself is entered in the lower right of the dialog. Start by entering the “Starting Energy Price.” If the pricing changes over the course of the EPS run, you can enter that data in the table below "Starting Energy Price."

If the pricing will include Peak Demand Charge, you must place a checkmark in the box beside “Include Peak Demand Charges?” When this is done, the two fields used with this will become available. Enter the value for Peak Demand Charge and Billing Period. The Billing Period is used to convert the peak demand charge, which may be calculated for the month, year, or another period of time, into a daily cost which can be added to the energy cost to obtain the Daily Cost.

Note: You can change the units for the energy pricing by right-clicking on the current units and choose "Units and Formatting." This allows you to change the units and the precision that the data is displayed.

Click "Close" to return to the Energy Costs manager. When you click a cell in the Energy Price column, the energy price definition that was created will be available for selection.

Once the energy pricing and the elements to be used in the analysis are selected, the analysis can be run.

Note: You must compute the scenario before you can calculate the energy cost.

Click the Compute icon in the upper left of the Energy Cost manager. Once completed, the pumps for which the calculation was run will appear in the window on the left side of the dialog. To view the results for an individual pump, select one of them from the window on the left. A Results table will appear on the right side of the manager.

You can also view the available results fields as a graph by selecting the Graph tab. To select which result field to view, click the pulldown and select the field.

Note: to see general results for all pumps, you can select the item “Pump Usage” in the window on the left; a new table will appear on the right side of the dialog.

Energy Management

Power Meters

Carbon Emission Analysis

Carbon Emission calculation is included with Energy Cost analysis. You can choose the pumps to be included for analysis at the same time as you select which pumps to include with the energy cost analysis.

In order for the carbon emission analysis, you need to enter a Carbon Dioxide Emission Factor to complete the analysis. To do this, click in a cell under the column header Unit Carbon Emission. This will open the Unit Carbon Emission dialog. Create a new definition by select the New icon, then enter your value for the carbon dioxide emission factor. Click “Close” to return to the Energy Cost dialog and choose the new unit carbon emission definition from the pulldown menu.

When you select the Compute icon in the upper right, it will now calculate the carbon emissions from the pump.

To view the results, select “Pump Usage” directly under the scenario name in the window on the left. In the table, scroll all the way to the left. The Carbon Emission results field will be the last column.

See Also

Product TechNotes and FAQs

Haestad Methods Product Tech Notes And FAQs

External Links

Water and Wastewater Forum

Bentley Technical Support KnowledgeBase

Bentley LEARN Server

Comments or Corrections?

Bentley's Technical Support Group requests that you please confine any comments you have on this Wiki entry to this "Comments or Corrections?" section. THANK YOU!

The model has been uploaded.

Overview

The Flushing tool has greatly been improved.  The new flushing module is easy to setup, easy to run (you can run a selected event or all events), and easy to generate printer ready reports. Both conventional and unidirectional flushing can be arranged under certain area or study. 
 
In earlier builds of WaterGEMS/CAD, flushing was controlled in the flushing alternative.  Flushing is now under the Analysis menu (Analysis > Flushing Manager).  If a user opens a project created in an earlier build, the data in the flushing alternative will be transferred to the flushing manager.

There has been a new criteria added "Target Shear Stress" along with the Target Velocity. This field can be used as a requirement to test the flushing event run. 

Reasons to Flush

• Operating hydrant to assure that the hydrant will operate properly when called on in an emergency
• Removing stale water
• Increasing disinfectant residual
• Removing dissolved material
• Removing settled solids
• Removing attached solids
• Removing bio-films
• Removing contaminants after a contamination event

Categories

• Movement of dissolved matter (includes disinfectant and taste and odor) - Velocity and shear stress are inconsequential.
• Removal of settled and loosely attached material (includes color and turbidity) - Very small increases in shear stress are all that is required.
• Removal of attached material (includes bio-films and attached solids) - More substantial threshold shear stress must be met.

Work Flow for Modeling Flushing

• Start with a calibrated model
• Start Flushing Manager
• Create Study
• Create Area/Set up Options
• Create Events
• Compute Study Area or Event
• Create Area/Set up Options

To perform an analysis of a set of flushing events (i.e. a flushing area), the user must creat flushing events.  Upon opening the flushing manager initially, there will be a default study, "Flushing Study" which will have one area called "Base Flushing" in the left pane.

The user creates new studies or areas by right-clicking on the study node in the left pane.  By right-clicking on the area a new event can be created.

Identifying the Buttons Left to Right

• New:  creates new study, area or event depending on which node is highlighted
• Delete:  deletes the highlighted study, area or event
• Rename:  to edit the name of the highlighted study, area or event
• Compute:  starts analysis of highlighted study or area
• Flushing Browser:  opens the flushing results browser
• Report:  opens up a preview of the operator report
• Move Up:  moves selected area or event up the list
• Move Down:  moves selected area or event down the list
• Zoom:  zooms to extent of selected study, area or event
• Highlight:  highlights elements in selected study, area or event
• Expand/Collapse:  expands or collapses selected node
• Options:  enables user to set default colors and extent of view in conventional flushing
• Help:  opens flushing help

Within a flushing area, the user defines the representative scenario, target velocity and shear stress, pipe set, method to determine flow (emitter or flow) and auxiliary output if desired.  It is a good idea to create a selection set corresponding to the pipe set before entering the flushing manager.

• Representative Scenario:  This establishes the boundary conditions (tank levels, pump status, demands) for the area.
• Output Scenario:  This is created automatically the first time the area is computed.
• Target Velocity:  The velocity that should be exceeded for the flushing to be considered successful for that pipe.
• Target Shear Stress:  The user may specify a Target Shear Stress or a Tar Velocity, or in addition to a Target Velocity.  Both defaults are zero.
• Pipe Set:  By clicking on the ellipsis button the user can select the pipes or a selection set.
• Nodes of Interest:  Auxiliary results are saved to these.  They are usful for monitoring low pressure during flushing.  This is an optional field.
• Flushing Flows:  The user can specify either emitter coefficient for the hydrant or junction being flowed or the actual flow rate.  Because the flow rate depends on pressure and the user usually does not know the flow rate ahead of time, it is usually more accurate to specify an emitter coefficient.  Do not specify both an emitter coefficient and a flow.  Typical values are 250 gpm/psi^0.5 (20 L/s/m^0.5).
• Auxiliary Output:  The user can save values for all elements from each event.  However, in most cases the user is not interested in values far from flushing.  Therefore, the user must specify conditions for element data to be saved and available for display for individual events.  If the box, "Includes nodes with Pressure less than?" is checked, properties for elements with pressure less than the specified value are saved for display.  If the box, "Include pipes with velocity greater than?" is checked, properties of pipes with high velocity are saved.  This makes it possible to use color coding to display results of flushing without saving a great deal of unneeded values.

The user then creates events within an area.  It is assumed that the flushing events are conducted in the order in which they are listed.  The key to order is usually to flush from clean water into un-cleaned areas.

Conventional events are made up of the hydrant (or junction) to be flowed.  These events have an advantage of being very easy to set up a large number of conventional events in essentially one step.  The user will see the Selection dialog where individual junctions or hydrants are selected.  Junctions or hydrants can be selected by polygon or they can be selected based on a selection set that has been previously defined.  If not all the nodes in a polygon are to be flowed, it can be helpful to have a selection set done already.

For UDF events, they must be created one at a time because the user must select flowed elements, controlled elements and optionally the pipe run to be flushed.  In this case a special form of the select dialog is opened.

The events tab enables the user to get a quick view of the events that are contained in the area, and if desired, make events active or inactive for the next run.  The notes tab enables the uwer to enter a text description of the area.

In creating a UDF event, use the second button to select the operational elements (hydrant, junction, valve).  If a hydrant or junction is selected, it is considered to be flowed.  If an isolation valve or control valve is selected, these are considered to be closed.  If a pipe element is selected, the default is that the pipe is closed.  If the user selects the third button to select the pipes will be a part of the pipe run.

In creating a UDF event, use the third button to add the pipe run elements.

Once an event is created, if the event is expanded in the left pane, there is one row for each element that is flowed, closed or part of a pipe run.

The element label and type are properties of the element selected and the status is an editable field (unless it is a flushing element such as a hydrant) indicating if the element is open/closed, flowed or part of a pipe run.  The flow emitter or flows specified in an area tab can be overwritten by checking the Specify Local Flows check box for that element and inserting a different flow or emitter.

Note fields are very important if the results of the flushing analysis are to be given to operators to locate elements to operate.  The notes may included an address for a hydrant or at a location of a valve that needs to be closed.

Flushing Results Browser

The flushing results browser contains the results of a flushing run listed by event.  The content of the browser corresponds to the current scenario.  If it is not a flushing output scenario, no events would be displayed.  The scenario can be switched to the flushing browser in the main drawing or by picking the button next to the output scenario selection in the right panel of the flushing manager.

Before opening the browser it is helpful to set up color coding and annotations that will highlight the flushing events.  Usually color coding pipes by velocity or shear stress, and junctions and hydrants by demand, will be the most useful.

Conventional Results

UDF Results

Toolbar Buttons on Flushing Results Browser

• Zoom:  zooms to extent of flushing event
• Highlight:  highlights elements in flushing event.  In highlighting, the pipe run color will override element symbology color coding.
• Reset:  cancels out the selected event and displays results for representative scenario
• Report:  opens preview of flushing browser report
• Help:  opens flushing help

Flushing Area Report (Flex Table)

While the Flushing Results Browser displays flushing results on an event basis, the flushing area results flex table presents the results on a pipe basis listing whether the pipe met the flushing target and which event was the most effective in flushing that pipe.

With the current scenario set to a flushing output scenario, open the flushing flex table.  By default, the table will open with all pipes.  If the model is large it is helpful to make a selection of elements and pick "Open on Selection" when opening the flex table.

Flushing Notifications

Reports

The user can identify the extent of the drawing that will appear in the optional reports.

Default Report Options

User Defined Report Options

Before opening the operator's report button, the modeler should:

1. Set up the desired background layer

2. Decide the extent of the view to display and if additional views are desired, set up those views.

3. Include detailed notes to help the operators locate the elements (e.g. an operator may not know where H-21 is located but will know "Hydrant in front of 31 Elm St.".

Operator Report

The operator report consists of three types of pages for each event:

1.  Text description of the event indicating which elements to operate

2.  Drawing of the event

3.  Form which flushing operator can complete to describe results of flushing for feedback (optional).

In addition to the default drawing of the event, the user can create "Secondary Views" which may for example, zoom into details of a complex intersection.  To do this, right-click on Report Views in the left pane and select Add Secondary View.  Draw a box around the extents of the secondary view and click Select New Report View.

The view that appears when the report is open is called a Preview.  With this preview, it is possible to:

• Change page set
• Print
• Export to a variety of file formats including .pdf and text file
• Transmit via email

The report can be saved and it is possible to zoom and pan within the document.

Example of a Conventional Report

Example of a UDF Operator Report

External Links

Overview

This Technote describes the process by which a user can import demand information from a spreadsheet using Modelbuilder. It assume Bentley WaterCAD or WaterGEMS V8i (08.11.XX.XX). The process is slightly different in V8 XM (08.09.XX.XX).

Background

In WaterCAD and WaterGEMS, demands can be entered as a base flow plus a pattern, or as a unit demand type and count. Also, multiple demands can be entered for each node (junction, hydrant, etc.)

If your demand data is contained within an Excel Spreadsheet and you have a field that contains labels that match your model's node labels, you can use the Modelbuilder feature to import them. For example:

Note: If your demands are in shapefile form, you should use the Loadbuilder tool, which can utilize the spatial information contained in the shapefile to assign demands, using many different methods. 

If you attempt to import this information using Modelbuilder, you may end up with the following unexpected results: 

This is due to the user selecting "junction" as the table type, which only provides read-only "demand" attributes to link your data to.  

Preparation

1. First, you should of course ensure that all your junctions and other elements are present in the model. When we import the demands from the spreadsheet, they will automatically update these existing elements.
2. Next, if you have not done so already, you'll need to set up any demand patterns that you'll be using. These are typically diurnal curves that adjust the base demand over the course of the EPS simulation. Go to Components > Patterns. Create a new hydraulic pattern and enter the starting multiplier along with the table of time/multiplier:

1. Open your source spreadsheet and ensure that it is formatted properly. Ensure that you have columns for the junction label, base demand and pattern, with a header at the top (see first illustration further above.) Ensure that the labels for your patterns match the ones in the source file that contains the loading data. If you would like to use a fixed pattern, simply enter "Fixed" under the pattern column for those junctions. (or, omit the pattern column altogether, if all junctions will have fixed demands.) 

Properly Importing your Demands in Modelbuilder 

Note that when you import demands using this process, they will override any previous demands assigned to those nodes included in the spreadsheet. So, this process cannot be used to 'update' an individual demand for nodes that have multiple items in the demand collection. All of the demands that should be present for a particular manhole should be included in the spreadsheet when using this process. 

Note: if you have WaterCAD or WaterGEMS V8 XM Edition (08.09.XX.XX) then the following Modelbuilder steps will be slightly different, as that version is older. The basic process is the same though.

1. Start a new modelbuilder run by going to Tools > Modelbuilder and clicking the white paper button. Select your data source type and then the file itself. Click the checbox next to the layer/worksheet that contains the data. You can click "show preview" to check the data in the later selected:

1. Click Next and uncheck the "create nodes if none found at pipe endpoint" check box:

1. Click Next and uncheck everything except for "update existing objects in destination if present in source". This is because we are updating elements, not creating or deleting them.

1. Click Next and accept the default "Current Scenario" and "Label". This is because we will be updating our current scenario and using the WaterCAD/GEMS label field.

1. Click Next to display the field mappings. This is an important step. First, click the layer on the left side (representing the worksheet containing your demands) and select "Junction - Demand collection" as the "Table Type". This is because the data that we are updating is not directly within the junction itself, but within the junctions' demand collection. A collection means that there are multiple items for each individual junction (composite demands are possible.) For example, you may have noticed that there are two individual demands for J-1 in the source spreadsheet shown in the first illustration. This is a composite demand.

For the "Key fields", select the column header that you used for the labels (most likely "Label".) This is used to link the demand entries with the junctions in your model.

In the bottom right corner, you must map fields in your spreadsheet to fields in WaterCAD/GEMS. This is because WaterCAD/GEMS cannot interpret your labels. For example, if you had a column called "Base_flow", there is no way for it to know that this means the Base Demand.

'Demand (Base)' - this should be mapped to your base demand column. Ensure that the correct units are selected.

'Pattern (Demand) (Label)' - this should be mapped to your pattern column

1. Click "next" and choose "yes" when prompted to build the model. You can uncheck the options concerning selection set creation. 

In the Modelbuilder Summary, you should receive a message stating that a certain number of your junctions were updated.

1. Close Modelbuilder and examine your demands. You can use the Demand Control Center (under the Tools menu) to easily view all demands:

What if I have unit demands?

If you have unit demands (unit demand label + count), you'll need to do a separate Modelbuilder run using a slightly different process. The unit demand information will need to be in a different worksheet in your spreadsheet (or a different spreadsheet altogether) with columns for the junction label, Unit demand, unit demand count and Pattern:

Instead of defining patterns in your model, you'll need to first import the Unit Demand types, under Components > Unit Demands. Either click the "new" button and define them, or import some commonly used ones from the engineering libraries (purple book icon)

In the last Modelbuilder step, you would select "Junction - unit demand collection" as the table type, instead of "Junction - demand collection". You would map the following fields:

'Unit Demand (Label)' - this should be mapped to the column that represents the type of unit demand.

'Number of Unit Demands' - this should be mapped to the column that represents the 'count' of units. For example, if the unit demand is "Residential" with it's demand representing 1 house, then a 'count' of '10' would represent 10 houses. The program will multiply the unit demand by the count to acheive the total unit load.

'Pattern (Demand) (Label)' - this should be mapped to the column that represents the pattern associated with each unit demand.

After Modelbuilder imports the data, you can view your unit loads in the Unit Demand Control Center, under the Tools menu. This tool will also show you the computed demand based on the unit demand and the "number of unit demands" (the count.)

What if I want to place demands on hydrants?

To import demands into hydrants instead of junctions, you would select "Hydrant - Demand collection" as the table type, instead of "Junction - Demand collection". Or, "Hydrant - Unit demand collection" if using unit loads. However, hydrants usually represent demands that would only occur during a fire (using the automated fireflow routine or emitter coefficient). So, demands are typically not assigned directly to them.

See Also

Product TechNotes and FAQs

Water and Wastewater Forum

Haestad Methods Product Tech Notes And FAQs

External Links

Bentley homepage

Bentley Technical Support KnowledgeBase

Bentley LEARN Server