One of the most fundamental resources cities have is the complex underground pipework infrastructure. Sewer lines carry sewage and wastewater to its treatment facility station, and underground plumbing also provides water and natural gas to consumers. However, it is no secret that the pipelines running underground are slowly deteriorating. Cities employ routine maintenance to maintain the network. The use of pipe penetrating radar (PPR) helps to determine which areas need attention most.

How Pipe Penetrating Radar Works

Pipe penetrating radar is a variation on ground penetrating radar (GPR). Like its counterpart, pipe penetrating radar uses an electromagnetic pulse to help map underground pipelines and the surrounding area. It is a nondestructive testing method that detects defects and cavities from within the line and outside the mainline diameter. (Learn more in "The View Underground: Ground Penetrating Radar.")

PPR works by sending a robot equipped with two or more ground penetrating radar antennae into the pipe. The robot moves through the line and transmits data to the surface. The data is then recorded via a closed-circuit TV in a process called a CCTV inspection. The transmitted data may include sonar, ultrasound and laser information. However, this is optional. Once the scan is complete, software analyzes the data and helps to pinpoint any cavities or defects from within the pipe or surrounding area.

Some trenchless rehabilitation projects require the use of PPR before beginning. Areas interested in using pipe bursting technology to increase line capacity need an idea of the current soil conditions. By sending a robot into the line, workers not only get a sense of line quality but also how stable the surrounding area is before sending through the pipe bursting mandrel.

Advantages of Using PPR

A significant benefit to using PPR over traditional methods is its nondestructive nature. Workers no longer need to dig up the line to visually inspect the condition. Robots used in PPR enter the pipe through a manhole or other access point. Once inside, the robot moves along the surface of the pipe mapping the interior surface.

Some areas use ground penetrating radar, the technology that spawned PPR, instead. However, GPR is significantly more limited in the data it returns. While it can help determine a buried pipe's location, GPR cannot assess wall thickness which allows indicating its overall quality.

Equipment used in PPR has the capability to take quantitative measurements of the pipe interior. Other methods of line inspection do not have the ability to collect three-dimensional geometric data from within the line. Workers can then use this data to determine any variances among manufacturers as well as a deviation from industry standards. All information gathered during a PPR survey allows workers to decide which areas need rehabilitation more significantly than others. The use of PPR allows trenchless contractors to decide whether a pipe would benefit from replacement via pipe bursting, CIPP repair or sliplining based on the thickness of the pipe and the rate of decomposition and damage. (Read on in "Sliplining or Pipe Bursting for Pipe Repair?.")

Pipe penetrating radar also has the advantage of being more cost-effective than traditional inspection methods. There is no need to excavate areas to assess the lines visually, which is costly. PPR in a waterline application allows contractors to see the early and evolved signs of blockages like tuberculation and corrosion.

Pipe Penetrating Radar Availability

PPR is steadily becoming more common throughout the United States. Large cities like Denver began testing the successfulness of these robots in 2012. Areas in California and Pennsylvania have also utilized radar for years. Workers use pipe penetrating radar worldwide.

Of course, the aspect that affects availability the most is the number of operators available in an area. The use of any type of ground penetrating radar, which includes PPR, must be completed by a certified technician. Operators undergo training, which familiarizes them with their radar model and shows them how to identify different items on the screen. There are various levels of training which includes an apprentice level for new operators to work with an experienced technician while receiving their Level I certification.

Training courses take months to complete, and operators should get recertification every few years. As each model of ground penetrating radar or pipe penetrating radar is different, new models require recertification to ensure proper usage for overall safety. Due to extensive training and the relative newness of PPR, not all areas have certified technicians to operate this machinery.

Pipe penetrating radar is a revolutionary trenchless technology which helps cities determine which areas need rehabilitation most. By mapping out the underground network of pipes, workers can categorize problem spots to streamline maintenance schedules.