Emerging Technology (Sewer assessment systems)

Sewer lines encounter various factors that affect their smooth operations. The factors may include the inability to withstand the pressure of the fluids flowing, the presence of foreign objects that may be flowing together with the flowing fluids among others. As a result, this may lead to cracking of the sewer walls. Cracked sewer walls consequently lead to the collapse of the pipelines, infiltration of groundwater into the system and the exfiltration of waste/ sewer water into the ground thereby causing environmental pollution.Also, sewer lines always cover a vast distance, and this makes constant monitoring a toll order. It is with this in mind that advancements in sewer monitoring and assessment systems have been made whose purpose is to survey the sewers accurately and detect flaws that may cause the effects mentioned above.

Before the development of such systems, sewer monitoring was done through either manual surveillance through on-the-ground assessment or CCTV cameras. The CCTV cameras were remotely controlled and were moved from point to point in the sewer network and relayed images to monitors. However, this mode of surveillance was not useful since they were prone to errors and inaccuracies as a result of subjectivity and difficulty in evaluation by the monitoring operator (Rebar).

Besides providing accurate assessment data, the systems were developed to save money used to repair sewer systems that have collapsed. For example, Germany uses approximately 100 billion Deutschmarks to repair collapsed sewer systems. The assessment systems developed include the PIRAT (Pipe Inspection Real-Time Assessment Technique) drawn up in Melbourne, Australia, the KARO (KAnaROboter), the MAKRO and the KURT all developed in Germany. The concept of sewer assessment using remotely driven machines is not new. However, the technology incorporated in the machines/ robots has increased in its sophistication.

The system was designed in Melbourne after a collaboration between the Melbourne water service and the Australian CSIRO Manufacturing Science and Technology. It was the first such system to be developed having been developed between 1993 and 1996. It uses a combination of a laser scanner and a camera. The device uses the scanner to perform an automatic evaluation of the sensory data. In flooded sewers, the laser scanner is replaced by a sonar scanner performing the same scanning function (Rebar).

The evaluation was conducted using the inbuilt interpretation system in a two-step procedure. In the first step, the system generates a 3-D model representing the sewer. The device then uses a combination of the scanned images and the artificial intelligence of the inbuilt computer to detect and classify damages in the sewer system.

It was developed experimentally in 1995. It is a six-wheeled intelligent untethered robot. It is provided with a map of the sewer network and is thus able to navigate through. It is also equipped with sensors that in addition to capturing essential assessment data help it in navigation for example through the sewer connections. It has a variety of sensors for odometry, obstacle detection, and inclinometers.

It is an entirely autonomous, untethered and self-steering robot designed for navigation through pipes of 30 to 60 centimeters in diameter. It consists of six segments and has a variety of capabilities as a result. It has seven microcontrollers, power batteries, sensors and the needed electronics for the purpose of assessment.

It is the most recent development having been sanctioned by the German Ministry for Research and Education. It was originally conceived as a prototype for inspecting concrete and vitrifying clay sewers with a length of up to 400m (Rebar). It is a semiautonomous robot with several sensory types of equipment attached. It is however tethered to a surveillance unit that limits the length to which it can reach while in the sewer system. It has inclinometers to show the angles and an onboard control program. As a result, it can correct for tilt in its movement and the wheel slippage while driving through the slippery floors of the sewer system. This, therefore, lessens the control burden on the operator.

Also, the KARO is equipped with a high-resolution TV technology (camera connection), various sensors such as 3-Dultrasonic, optical and microwave sensors (Oobject.com). The optical sensors and the ultrasonic sensors inspect the internal walls of the pipe detecting the position and the extent of damage to the pipes, the issues in the pipe walls that need correction and the adjacent pipe surroundings (Oobject.com). The microwave sensors inspect the soil surroundings of the pipe walls. Fuzzy logic technology is used to combine data from the various sensors and providing linkages among them. Besides, it conducts 3D measurements in hollow spaces using infrared thereby giving the device the accuracy needed to locate the position of the defects (Oobject.com).

As discussed earlier, data collected from sewer assessment systems are useful in averting sewer disasters. In history, there have been various sewer disasters such as the Fylde Street Disaster in 1957 where the sewer collapsed leading to a 120 foot-long hole. Through the use of the systems mentioned above, such disasters can be prevented and money that would have been used in repairs saved.