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In 2003, the Allegheny County Sanitary Authority (ALCOSAN) met with RedZone Robotics to discuss the applicability of advanced mobile robotic systems for the cleaning of their deep tunnel system (DTS). Approximately one year later the two organizations entered into a service agreement whereby RedZone began the design of a system that could meet the needs associated with entering, navigating, investigating, and performing useful work tasks within the DTS. The project was unique in that the system presented a challenge for mobile robotic technology since the robot would need to carry all the sensors, electronics, hardware, and software to allow for a successful operation within a volatile and unknown environment.

DTS, trunk, or interceptor sewer systems are critical components of a municipal conveyance system. These are the main arteries or thoroughfares collecting sewage from a wide area and transferring it to the treatment plant for processing. An increase in environmental awareness and a recent focus by regulatory bodies on the integrity of these systems has brought a new level of attention onto the survivability of these structures. Another factor influencing the renewed focus is end of serviceable life. These large structures were constructed up to 50 years ago and, in some cases, greater. When this factor is combined with the demands placed on these systems not only internally but through neighboring infrastructure projects, a great deal of concern is placed regarding how much life is left in these pipe systems. In other cases, these pipes might be structurally sound, yet infiltration of sediment and other materials over time has led to occlusion thereby reducing their effective capacity. Often times, this can contribute to a greater frequency of overflow events especially with combined sewer systems. Even though these structures are critical, inspection and maintenance is done infrequently, if at all. The difficulty lies in the unique characteristics of these pipes including:

Deep depths (sometimes greater than 100 ft.);

Long stretches between available accesses (sometimes greater than 1 mile);

Fully and continuously surcharged;

Strong flow rates;

Cloudy, turbid environment;

Sediment accumulations of various proportions and characteristics;

Suspected obstructions and partial blockages; and/or

Old, inaccurate drawings and little to no previous inspection information.

The incorporation of sensor technology, innovative software, robust robotic equipment for hazardous duty use, and computer-based control can be leveraged to provide qualitative and quantitative information on these systems. This information can be used by the municipality or consulting company to visually examine the systems and make informed decisions regarding the next steps associated with remediation, cleaning, or potential replacement. There are several advantages associated with a robotic assembly that can routinely enter and deploy within a DTS. One advantage is in the ability to visualize its surrounding and paint a picture of what is occurring within the pipe. Another advantage is in the ability to incorporate multiple sensors so that operators only need to track through the pipe once to collect all necessary information required to judge the condition of the pipe. Lastly, the ability to utilize work tools allows for the same system to remove obstacles or obstructions, scour, and agitate the sediment to clean the pipe and assist in the removal of the materials from the DTS.

Document Type: Research Article


Publication date: 2005-01-01

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