Case Studies - Fall 2021

Case Studies - Fall 2021
Regular maintenance with root herbicide reduces sewer overflows

Root problem eliminated on lakeside easement 


A neighborhood in Liberty, Missouri, had a heavily root-bound easement. Access was difficult, as the 1,280-foot line traveled across the backyards of houses situated on a lake. The line was laid unevenly, which gave roots more opportunity to invade. There were continual blockages, with several houses experiencing backups. The municipality put the easement on a saw, cut and flush routine program, conducted twice a year. However, they were called out for emergencies in between the maintenance visits as well, as there were constant problems. 


Duke’s Root Control applied RazorRooter II to the entire easement. The hose released and sprayed the foam in all directions, allowing it to adhere to roots and penetrate through wye connections to kill roots without harming trees or other aboveground vegetation. 

Result:  “A few months after the foam was applied in January, we ran our CCTV through the pipe, and the roots had decayed, like you see cigarette ashes crumble,” says Gary Harter, operations manager for the City of Liberty. “Our camera made it right through the pipe. We haven’t had any blockages since. This has saved our city a tremendous amount on time lost, wages and expenses. We can rededicate the time we were spending to different areas of the town.” 


Adjustable risers keep manholes at grade


 With a population of 66,000, St. Charles is Missouri’s ninth-largest city and was the state’s capital from 1821 to 1826. “We have old and new areas, which means we have a lot of odd-sized sewer structures,” says Cory Rackley, lead equipment operator. “Adjustable risers make it much easier to raise all these differently sized manholes to grade.”


 Since 2008, Rackley has been using Pivoted Turnbuckle Adjustable Manhole Risers, made by American Highway Products, to raise manholes precisely to grade without excavation, significant traffic closures, or the need for equipment to lift and set heavy concrete rings. The riser is a sturdy, flexible, galvanized ring made with steel that uses a turnbuckle to adjust riser diameter. Installation is simple and fast; one man sets the riser in the original utility rims and uses a screwdriver as a lever to expand it to fit. Since the turnbuckle leverage applies thousands of pounds of force, the riser seats in the rim tightly, providing a new rim for the manhole with no rattling or looseness. When installed properly, Rackley has never seen one fail.

Result:  At-grade risers are better for roads in many ways. They don’t set low, so water doesn’t collect around the manhole lid causing excessive infiltration; and they don’t set high, so vehicle tires don’t jar the lid and rim continually. And since risers are usually set just before paving runs, the newly raised manhole is surrounded by new, contiguous pavement, and that prevents water and freeze-thaw damage in the pavement around the manhole. 


Municipality puts accuracy of area-velocity meters to the test


A moderately sized U.S. Northwest utility had limited budgets for measuring I&I. They had learned of lower-cost depth-only monitors that might be used for this purpose, but were unsure of their performance accuracy. They had previously been using industry-standard area-velocity meters. While A/V meters had always proved to be accurate, they could be more than twice as expensive as DOMs. The difference between A/V meters and DOMs is that the former measures flow (volume) through both depth and velocity measurements while DOM singularly measures flow depth-only and rely on Manning’s equation or other algorithms for determining velocity. These algorithms required estimations of multiple variables influencing the velocity calculation.


The utility did a comparative study of the two technologies, co-locating A/V and DOMs. Data was collected for a month under a variety of weather conditions. Large variances were found in all locations, including a “false negative” where the DOM’s calculated value indicated a flow decrease when the A/V meter measured a two-fold flow increase. An additional false positive indicated an eightfold increase when, in fact, A/V meters measured only a 40% increase.

Result: The utility decided to continue using A/V meters from ADS Environmental Services for their accuracy and reliability. They determined that while A/V meters were initially more expensive for I&I study, there was significantly greater risk should they use the questionable DOM data to make much more expensive capital improvement project investment decisions. 


Superior 5-E electric smoke blower finds faults, odors, leaks and inflow

When testing laterals, building plumbing, or pumping or inspecting septic tanks, smoke testing is a quick and effective way to find plumbing faults that lead to odors, leaks and inflow. 

Superior Signal Company’s Superior 5-E Electric Smoke Blower easily connects to any clean-out, port or vent to smoke test the entire system in just a few minutes. The Superior 5-E Electric smoker gently pushes smoke throughout a system to find cracks or leaks and quickly identify problems. Made in the U.S., the durable Superior 5-E Electric smoker is competitively priced and comes complete with 8 feet of industrial grade hose. Used with Superior Smoke Candles, this cost-effective solution is ideal for hard-to-find odors, leaks and other faults in commercial, residential and municipal facilities. 


Failing stream crossing saved with trenchless point repair


An Atlanta suburb was experiencing severe infiltration from a failing corrugated culvert, installed years before as a stream crossing. The exposed 8-inch culvert was used as a sewer line between two manholes and a retaining wall was built directly on top of it. Rusting over the years caused a couple of dime-sized holes, allowing stream water to pour directly in. Traditional dig-and-replace methods required bypassing both the sewer and the stream to prevent sedimentation, in addition to demolishing and relocating the retaining wall. Contractor quotes were $90,000 and up, and would have required occupying adjacent homeowners’ yards for days with equipment and debris.


EnviroWaste Services Group’s Atlanta branch installed an 8-inch by 8-foot trenchless point repair, manufactured by Infrastructure Repair Systems. The repair was accomplished in a single, partial day from above the manholes with only foot traffic through homeowners’ properties. No bypassing of the sewer line or stream was required. EnviroWaste’s installation of the repair kit not only sealed the pipe from infiltration, but also created new structural capacity for the existing pipe.

Result: By utilizing the kit, EnviroWaste Services Group was able to repair the culvert for less than one-tenth of the cost of dig-and-replace methods. The infiltration was eliminated and the county avoided potential SSOs with virtually no stress for surrounding homeowners. 


Drain tools clean solid cement that poured through residential sewer lines  


Over 30 homeowners from North Winnipeg, Manitoba, were shocked when cement poured through their pipes. The city hired a contractor to grout a sewer trunk shaft when the combined sewer was breached. The grout entered the residential sewer lines, and damage was caused in their basements, bathrooms, bedrooms, living rooms and backyards. Residents were faced with anywhere from 4 inches to 4 feet of wet cement, and the residential lines were then blocked with the cement.  


After calling many plumbing companies in the area who were not up for the challenge, Aloha Drain Services was called to inspect the incident. They were armed with the right tools and got to work removing the cement. Using Internal Pipe Technologies’ Gator Drain Tools, they were successfully able to clear out the lines. They opened each pipe that was filled with solid cement grout using Gator Claw Heads and Reinstators. The lines were anywhere from 4 inches in diameter, then transitioned to 6 inches.  

Result: Aloha Drain Services successfully cleared out the sewer lines of 30 houses. The Gator Claw Heads lasted for 750 feet of dry cement without wearing out. Because of the ruggedness and durability of the heads, homeowners could have a fully operating drain system without replacing the lines. For the service lines that required full repair, Aloha Drain Services lined the whole pipe from the main clean-out to the city connection with IPT CIPP liners with 4- to 6-inch transitions. 


Sewer blockage detection using ultrasonic level sensors and data loggers


 A large East Coast metropolitan sewer district was looking for ways to help maintain its 68,000-mile sewer network and reduce problems associated with pipe blockages. With more than 15 million people generating over 1.2 billion gallons of wastewater each day, the sewer district was spending an average of $25.5 million every year clearing 75,000 blockages from its sewers — unclogging five house blockages and removing 33 tons of material from just one of its sewage works every day.


 Last year, 3,700 SonicSens 3 ultrasonic level sensors from Fluid Conservation Systems were installed and 5,000 more will be installed over the next year to help monitor the network through Sewer Depth Monitoring. SonicSens 3 uses ultrasonic technology to measure the level of wastewater in a chamber, information which can provide an early warning of blockages within the network. The sensor is installed within the chamber but avoids contact with the sewer contents, so the devices require less maintenance. SonicSens 3 was paired with Intelligens WW, a flexible data logger with the versatility to be tailored for a variety of specific user needs, for efficient data transfer.

Result: The sewer district now has an effective early warning system for sewer blockages. Should levels in a monitored area rise, the devices will alert the district to a developing problem within the network, helping to avoid flooding and pollution damage caused by blockage incidents. This is especially important as population growth and more extreme weather patterns put additional stress on sewer networks. 


Sanitary sewer system updated with remote monitoring capabilities


The Minneapolis Public Works Department needed to modernize the sanitary sewer system to meet the city government’s goals. Minneapolis had nine sanitary lift stations and 23 storm sewer pump stations spread throughout the city. None of the stations had remote monitoring capabilities, and the Public Works Department wanted to add this capability.


PRIMEX was chosen as the prime contractor to retrofit the existing stations by adding remote monitoring capabilities. The mandate was to develop and install a complete SCADA system that included the addition of digital cell routers on the Verizon network to improve monitoring. The upgraded system also incorporated a local computer memory at each site, ensuring that if for any reason the cell connection was down, the data would not be lost. The local Wonderware Edge graphical operator interface has native capabilities to both store and forward all data. When the Verizon communications are lost, the local OIT logs data to memory. Upon restoration of cellular communications, all of the historical information is backfilled into the historian so that there are no blackouts in data. This redundancy feature is the first of its kind and was successfully implemented for the city.

Result: The sanitary sewer system is now able to meet the department’s goals. Remote monitoring was added to all systems and helped improve its data analytics and enhance its ability to more effectively manage both storm sewers and sanitary sewers. 


Camera helps company reuse existing line


A company in Merritt, British Columbia, was awarded a job in Monck Park and called the professionals at Canadian Septic to install a new septic system. The existing gravity lines to the tanks were old, and they ran over 500 feet and through forested areas.


A technician from Canadian Septic used the Wi-Fi Inspection Camera Reel from Hathorn. They ended up having to go to one of the furthest restroom facilities in the park. There, the camera was put into the clean-out. Using the camera head from above ground in the woods, they traced and located the physical location where the clean-outs were, from inside the line.

Result: Canadian Septic was able to identify that there were no bellies present in the line. The camera allowed them to reuse the existing 4-inch gravity line. Hathorn’s Wi-Fi Inspection Reel was the best tool for this inspection because of its durability, ruggedness and reliability. The camera allowed the company to save photos and videos directly to a phone, saving time and money when preparing reports for customers. 


Scanning technology indicates recently replaced pipe to blame for I&I issues


A Texas utility had dug up and replaced a length of pipe three years ago and, in recent investigations, found that the new construction pipe was one of the top 10 biggest contributors to its I&I.  


 The utility performed a pilot study on approximately 5,000 linear feet of pipe using Electro Scan’s FELL Technology per ASTM Standard F2550 to certify watertightness of the pipes and effectiveness of various dig-and-replace projects within the municipality. The municipality also wanted to scan various plastic pipe materials to see if there was a difference in replacement effectiveness. Each line was also installed by a different contractor and was part of a different project.

Result: The survey indicated a potential leakage rate of approximately 100 gpm across five of the pipes that were scanned, with most defects found being leaking lateral connections and some sagging pipe sections. There were no CCTV callouts post replacement. The inspection gave the utility the information it needed to evaluate the effectiveness of the replacement projects with quantifiable data rather than interpreting a visual inspection. It was found that different pipe materials and different contractors did not change the outcome that the pipe sections leaked regardless of who did the install or what material was used. Electro Scan can be used to effectively evaluate rehabilitation and replacement projects, allowing municipalities to ensure they are investing in successful long-term repairs to their collections systems. 


Manhole inspection finds nearly 90% of system’s I&I


 Utica, New York-based Subsurface Utility Imaging (SUI) — a company dedicated to location and inspection of underground infrastructure assets — was engaged to inspect the pipelines and 300 manholes of a municipal sewer system. CCTV and smoke testing were used for the pipelines, but co-founder Robert Korosec, PLS, needed a better option for the manholes.


 Korosec and his crew used Envirosight’s CleverScan, a system that uses automation and photo capture technology to gather high-resolution images and 3D point clouds of manholes. “Given the large amount of manholes on this project, and their poor condition, I felt we had to give it a try,” Korosec says.

Result: With minimal training, SUI crews were able to put the system to work immediately, inspecting an average of 50 manholes per day and completing the manhole inspection portion of the contract in less than a week. Of the total project cost, just 40% of the contract was spent on manhole inspection. However, manhole inspection found far more sources of I&I. “The pipelines here were in pretty good shape, and we estimate were only contributing 5 to 10% of total I&I,” Korosec says. Manhole inspections identified up to 90% of the I&I sources in this municipal network, allowing the city to prioritize easier manhole repairs and eliminate major sources of I&I. 



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