Under the USEPA’s Stage 2 DBPR utilities are required to identify locations in their water distribution systems that are likely to have high concentrations of two groups of DBPs; trihalomethanes (TTHM) and haloacetic acids (HAA5).
Building a detailed, calibrated, extended period simulation (EPS) model to identify locations with high water age in the system, is the easiest and most expedient way to implement initial distribution system evaluation (IDSE) studies, required for Stage 2 DBPR compliance.
Visit the USEPA Web site for more information about IDSE and Stage 2 DBPR compliance
WaterCAD V8 XM Edition includes a set of new tools designed to assist utilities in complying with these regulations. WaterCAD users are now able to easily implement models for IDSE and Stage 2 DBPR compliance using the new tools to:
1. Demonstrate that the utility has a well calibrated model
IDSE studies must demonstrate whether calibration is complete, by presenting a graph of predicted vs. measured tank levels for the storage facility with the highest residence time in each pressure zone. Also, a time series graph of water age results with predictions for the entire EPS run is required.
The new IDSE toolset in WaterCAD helps engineers import and plot discrete series of field data obtained from SCADA systems, data loggers, or manual data sources, along with predicted tank levels and water age results from an EPS run.
2. Comply with the model integrity requirements
Utilities must also demonstrate that the model used for the IDSE study includes at least 50 percent of the real pipe length, and 75 percent of the pipe network volume, among other requirements to guarantee the inclusion of essential pipes, storage facilities, pumps, valves, with realistic controls that reflect standard operation strategies.
A new type of report has been added to automatically create inventory summaries with total length of pipe and volume of water, facilitating reporting and compliance with USEPA requirements on this matter.
3. Calculate, display, and perform statistics on water age
The new Post-Calculation Processor delivers the statistical analysis capabilities required by USEPA. Engineers can run an extended period simulation (EPS) to calculate water age, display results with the already available graphing tools, and use the new Post-Calculation Processor tool to:
Calculate average water age at each element between two specific simulation times.
- List the water age results in ranked order for the entire system.
- Build a histogram showing the number or percentage of nodes with various water age ranges.
Learn more about WaterGEMS V8 XM Edition