The City’s original hydraulic model had been built using another company’s software with a customized graphical user interface (GUI). The GUI had been developed under earlier versions of Microsoft Windows and could not be opened in the later versions of Windows. . 'We looked at the situation and recommended that the best solution would be to migrate the data into InfoWorks WS,' says Ahmad Habibian, who is Black & Veatch’s National Practice Leader for Pipeline Rehabilitation.
The data was successfully imported into InfoWorks WS and one of the first uses has been to analyze and improve plans for a new pressure zone. It is also being used to determine whether infrastructure upgrades are needed to serve new developments and to verify the adequacy of the supply for new developments. In addition, InfoWorks enables the City to look further ahead and plan the capital improvements that will be required to cope with growing demand over the coming decades.
Charles Town’s population is growing, particularly as property prices are becoming very expensive in the neighboring Washington DC area. “Water production has been increasing significantly and is expected to continue, however, planning tools like InfoWorks WS allows the City to model for shifts in the housing and commercial markets for greater flexibility and planning,' says Jane Arnett, Manager of the City’s Utility Board. Several large areas of farmland around the Charles Town are scheduled for major housing developments to cope with the influx of people.
The City was established in 1786, though it was severely damaged in the 19th century during the Civil War. Its water is sourced from the Shenandoah River and the installation of the supply system began in 1914. 'There are a lot of galvanized pipes in the system with a significant amount of leakage,' says Dr. Habibian. Resolving this is a priority. The network includes many small-diameter pipes, which bring pressure problems. Diameters range from 16” (400mm) to 0.75' (19mm) and 40% of the pipes are 2' (50mm) or smaller.
Black & Veatch began working on the project in November 2006. The original model was converted straightaway to InfoWorks and put to work on a variety of tasks. The original model did not contain a separate component for leakage. 'We knew that was a deficiency in the system,' says Dr Habibian. An important first step was to revise the diurnal demand to identify the leakage component, which is about 30%, in order to increase the accuracy when peak demand is calculated. 'The InfoWorks model doesn’t multiply the leakage factor - it only multiplies the actual demand figure,” he adds. “That makes a big difference.'
One of the key aims of the model is to analyze the distribution system’s performance, particularly with regard to the new high pressure zone that is being introduced. Charles Town currently has two pressure zones - the main zone and an existing high pressure area. The new zone will increase the supply pressure within an area of high terrain to the north and west of the city.
InfoWorks has played a key part in maximizing the efficiency of the new zone’s design. The zone had already been planned prior to Black & Veatch’s appointment and Black & Veatch has been able to use InfoWorks to alter the design points for the pumps. The original pump design was oversized, and would have created extreme pressure fluctuations as well as being inefficient. 'We identified that as an issue,' says Dr Habibian. Black & Veatch therefore recommended reducing the impeller size. Testing in the InfoWorks model has confirmed that better performance will be achieved.
All three pressure zones will continue to expand to serve Charles Town’s growing population. Average water demand in mid-2004 was about 1.15 million gallons per day (4.35ML/day), and this had grown by 20% within two years. The current plant capacity is a peak flow of about 2.8 million gallons per day (10.6ML/day), but peak demand is projected to reach almost 7 million gallons per day (26.5ML/day) by 2035.
A key role for the InfoWorks model is in identifying the appropriate share of the costs to be paid by any developers that require new pipelines. The model has already been used to explore the relative costs of a pipeline that will serve two developments. The diameter and length that each would require individually was first identified and then used to determine the share that each should pay towards the joint, larger pipeline.
Different pipe sizing would be needed if the City takes the opportunity to integrate the new pipes into a loop, which would help in water provision elsewhere. InfoWorks has similarly been able to explore the sizing for this solution. Comparison of the pipes required for each scenario enables the costs to be apportioned fairly between the City and each developer, says Dr. Habibian.
InfoWorks also enables checks to ensure that new developments would have adequate fire flow. 'We run fire flow analysis for every scenario and for any developments that are proposed,' says Dr Habibian.
The model can be used to predict much further ahead. The City is now able to forecast required enhancements to its distribution system for regular intervals to 2035. This covers aspects such as additional storage and pumping capacity. 'We have costed these to provide a capital improvements program,' says Dr Habibian. This can be updated as necessary to take account of the scale of house building that takes place as people continue to move to Charles Town.