Sewer Inspection Made Easy
February 15, 2012During a recession, finding money for construction projects and other types of infrastructure maintenance becomes difficult. At the same time however, technology and equipment continue to advance in the trenchless industry, and one city has been using that to its advantage.
The City of Beaver Falls, Pa., is getting creative in its approach to maintenance, particularly with sewer inspection and repair. Beaver Falls is a city located about 60 miles north of Pittsburgh with a population of about 10,000. A few years ago, the city wanted to begin an operation to clean and inspect all its sanitary sewer lines, many of which were built in the late 1930s.
Like many other small cities, Beaver Falls owns and operates a jet/vac truck for cleaning manholes and sewer pipes. Using the jet truck, city workers clean sewer walls using high pressure water, then vacuum out obstructions when necessary. Generally, cities will then hire other companies to come in and perform a more in-depth pipe inspection to allow them to find and assess damaged or cracked pipelines. One of the reasons for this is because small cities typically do not have the right equipment, and therefore, the ability to perform an in-depth inspection. The appropriate method involves actually getting inside the pipelines and physically viewing the damage. This is done by using a camera, or “crawler,” that goes inside the pipe and relays images and data back to a computer on the surface. The results then tell the companies doing the inspection if the pipe is intact or if they need to consult engineers about the best course of action to repair it.
In the case of Beaver Falls, the city got to a point where it could no longer afford to bring in sub-contractors for that type of work. So, public works superintendent Bruno Gratteri came up with a plan. He thought that by obtaining the money through a grant to buy new equipment, the city could do the inspection itself.
Pat Burdine works for the Beaver Falls public works department as the jet truck operator and pipe crawler/camera operator. He said that in 2007, as the city was becoming more financially strapped, the public works department decided to apply for the grant. “We have always had a jet truck for cleaning obstructions and maintaining approximately 27 miles of sanitary sewer lines in the heart of Beaver Falls, not including the outlying areas of the city and storm sewer systems,” Burdine said. “When we had a problem that needed televised, we would have to hire outside companies to tackle these jobs. We got tired of using these other companies because the cost was just too much.”
When the city was able to obtain the grant, it could afford to buy new equipment, including an Envirosight ROVVER 125 inspection crawler to navigate inside the sewer lines. Burdine had to first become Pipeline Assessment and Certification Program-certified, by NASSCO to be able to operate the equipment. In 2008, he completed the requirements, allowing him to operate the ROVVER crawler and the computer software needed to view the results. Thus, the city began the process of cleaning and televising the sanitary sewer lines.
According to Envirosight, ROVVER inspection crawlers have a modular design that allows reconfiguration for any combination of pipe size, material and condition. ROVVER crawlers are short, steerable and have the ability to navigate past debris and obstructions, climb offsets and pass through inverts and curved access points in the sewer. Three chassis sizes allow inspection of pipelines anywhere from 4-in. to 60-in. in diameter. ROVVER uses a fully automatic cable reel, which has a tension sensor to reduce the pulling burden on the crawler (thus extending its range), as well as to prevent cable tangles during backward crawl. The systems are also compact and consume minimal power as they are also more portable and require significantly less operational overhead than other crawlers.
“The reason we actually chose it is because it is smaller and more compact that other crawlers that are bigger and more bulky,” Burdine said. “This one has four wheels and you can easily maneuver it around obstructions in the pipe.”
Burdine said because most of the sewer lines in the city are so old, some are made with brick. Therefore, chunks of brick are a huge obstruction that the city encounters while trying to steer the camera through the pipes during inspection. But Burdine also said most of the pipelines are made with terra cotta pipe ranging from 6-in. to 24-in. in diameter. The actual damage to those sewer lines mainly comes from tree roots that have grown over time, putting tension on the outside of the pipe.
Another major aspect of the inspection process is the software that is used to view and analyze the data that is transmitted back to the surface by the crawler. In Beaver Falls, Burdine and his crew use WinCan 8. WinCan software is a focused application for the administration and inspection of wastewater networks. The software essentially assists workers in analyzing the images taken by the crawler/camera inside the manhole or sewer line. It has the ability to analyze damage, such as cracks and leaks and determine the severity of the problem. According to Burdine, WinCan 8 uses a scale of one to five to measure the damage, five being the most severe. From the data collected, the city can then make the best decision on what to do next without the assistance of engineers. In most severe cases, the pipes often need to be rehabbed or slip lined.
Burdine’s crew uses an old resurrected police minivan to support the equipment. It runs along the surface so that workers can steer and track the crawler inside the sewer. In Beaver Falls, the sewer pipes are about 350 ft from manhole to manhole.
Burdine said the job of inspecting all the sewer lines in the city is a long process and that it may take another four years before the city finishes the sanitary sewers before starting on the storm sewers. But Burdine said it will be well worth it for the city to continue to do the work itself.
“The cost is the biggest advantage,” he said. “It could cost anywhere from $100 to $250 an hour to pay another company to do this. It would more or less bankrupt the city to have a sub-contractor come in for this work,” he said. “Without our superintendent Bruno, none of this would be possible. This was his vision with my input on the details.”
Andrew Farr is an assistant editor for Trenchless Technology.