Updating Historic Sewers
Updating Historic Sewers: Technology helps Indianapolis manage overflows, plan projects.
As published in American City & County Magazine, July 2005
- CSO Monitoring
- Long-Term Monitoring/Data Analysis
- Proactive Collection System Management
By Patrick Carroll, Deputy Director of Operations, Indianapolis Department of Public Works
Like most American cities, Indianapolis has been facing increased scrutiny from residents about water quality issues. The U.S. Environmental Protection Agency (EPA) and state environmental agencies also are calling for Indiana's 105 cities with combined sewers (those that carry sewage and stormwater in the same pipes) to minimize or eliminate raw sewage overflows into local waterways that often occur after a quarter-inch or more of rain. In response, the Indianapolis Public Works Department has begun using a Web-based notification system to alert city employees to overflows and is creating a $1 billion plan to update its combined sewer system.
The Public Works Department relies on a network of flow monitors that record the speed and depth of material in sewer pipes. Traditionally, the monitors were read monthly by a technician who traveled to the flow meters and rain gauges to download their data, making it difficult to stay ahead of storms and overflows and to respond quickly. To monitor overflows between meter readings, public works staff would draw horizontal chalk lines on the city's 132 overflow outlets. If the chalk marks were washed away, an overflow probably had occurred.
City officials needed a new computer system that would alert them immediately to unusual flow conditions so they could steer the public clear of affected streams and rivers. The system also needed to integrate data from three different departments that recently had been combined to improve collection system management.
The Public Works Department selected IntelliServe, a Web-based notification system from Huntsville, AL-based ADS Environmental Services, and began installing it early this year. Now, public works employees can use Web browsers to see flow and depth data at meter locations throughout the collection system and determine if sewer lines are flowing as designed and to capacity or whether hydraulic problems, such as blockages, exist. The system alerts staff members to wet and dry conditions in the sewer system, analyzes trends and works with flow monitors made by multiple vendors.
In the short term, the system helps public works staff pinpoint operations and maintenance issues in the collection system, and in the future the city can use the data to model the collection system, treatment plants and plan capital projects. Currently, the city's Clean Stream Team, a group of public works staff and consultants, is developing a long-term control plan, which is the most ambitious water quality improvement project in the city's history. The plan, pending approval from EPA, will address the long-standing problems caused by combined sewer overflows and fulfill state and federal requirements.
Over the next 15 to 20 years, at least $1 billion will be invested to improve water quality by modernizing the city's 19th century sewer system. Through a wide range of capital projects, the improvements will reduce raw sewage overflows and, in many cases, eliminate overflows during storms. “I can't stress enough that accurate and reliable data is extremely important in developing capital improvement projects, especially projects as large as our long-term control plan,” says Carlton Ray, administrator of environmental engineering and member of the Clean Stream Team. He says the data the city collects now “will allow us to create precise models to demonstrate the effectiveness of our plans to the EPA.”
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