Potable Water Rehab in Oswego, N.Y., Without the Need for Bypass Pumping

Well the answer to that question may vary greatly depending on whom you ask, but the answer should always be “whatever it costs.” Compared to other areas of the world, the answer from someone residing in the United States may be much lower, as we have become accustom to having a constant supply of clean water at a very low price.

The primary reason for this is the massive infrastructure that has been put in place over the last century or more. This distribution portion of this infrastructure, that services the more than 50,000 local water systems, is primarily made up of cast iron and ductile iron pipes. Many of these assets are approaching or have passed their published useful life expectancies (for distribution pipe in water systems, it is 60 to 95 years. Source: EPA 2002 study). If you combine the age of the infrastructure with the growing demand, both population growth and per capita usage, breakdowns are inevitable.

With an average of 650 breaks a day in the United States, it is becoming a regular occurrence to see the local or national news reporting on a potable water main burst that has washed out streets or tied up rush hour traffic for hours. While the public fascination with these issues may be short lived, the problem continues to grow at an alarming rate.  The recent ASCE Report Card for America’s Infrastructure graded the overall drinking water system as a D- (the lowest grade given). Despite the billions spent each year on repairs and improvements the U.S. drinking water system faces an annual budget gap of over eleven billion dollars. The simple truth is that if we are to get ahead of this problem and address the growing gap we need to find more cost effective solutions to renew our crumbling infrastructure.

In 2011, 3M launched an innovative new trenchless rehabilitation solution that can deliver significant cost-savings compared to traditional dig-and-replace methods. 3M Scotchkote Pipe Renewal Liner 2400 is an NSF/ANSI 61 certified product that can be applied to potable water mains ranging from 4 to 24 in. in diameter. This product can be applied at either a 1.2-mm water quality coating to act as a corrosion barrier for pipes that are in good condition, or it can be applied thicker (up to 8.5-mm in a single pass) to provide an AWWA M-28 Class IV structural lining   for pipes with existing pinhole, cracks and leaks (thickness of application is dependent on pipe diameter and bury depth). The product can span these existing faults and deliver asset longevity and improved flow without the high cost of total replacement. The trenchless application process of installation can deliver significant cost-savings similar to other trenchless technologies, up to 90 percent reduction in excavation and paving costs. The project example below demonstrates how the fast curing properties of Scotchkote Liner 2400, combined with good planning and communication, can deliver significant cost savings by eliminating process steps (like bypass piping) that have both direct and indirect costs. These cost-savings will allow infrastructure owners to invest more of their budgets into preventative maintenance and improvement projects.

No-Bypass Project in Oswego, N.Y.

The Oswego Water Department had a section of distribution pipe that had a history of breaks and water quality issues. Specifically, the pipe had corrosion, severe tuberculation, brown/red water issues and three emergency repairs in two years. These issues resulted in repeated service disruptions for customers and high maintenance costs not uncommon with cast iron pipe of this vintage. To solve this problem within its current budget, the Oswego Water Department did a thorough analysis of trenchless rehabilitation technologies that could address water quality issues, provide a structural solution to limit the amount of future repair done to the pipe, and provide significant cost-savings over dig-and-replace. Oswego selected Scotchkote Liner 2400 and decided to do the installation as a Same Day Return to Service project. The trenchless application process and elimination of the bypass would deliver significant cost-savings and lower the total project time. The project included 2,265 ft of 6-in. cast iron pipe that had been installed in 1923.
Prior to making the decision to pursue a Same Day Return to Service project, several key success factors were identified by Oswego:
• Buy-in from key water utility and city officials
• Adequate pre-project planning to eliminate downtime during the actual pipe rehabilitation projects
• Selection of a rapid pipe lining rehabilitation product
• Effective resident communication
• Effective project management during the actual pipe rehabilitation project

Both the cleaning contractor (Mainlining Services Inc.) and lining contractor (3M Co.) worked closely with the Oswego Water Department on project specifics including:  location of access pits, project sequencing, reinstatement processes, resources required on site during each aspect of the project, resident communications, and permits or approvals for the project.

The in situ application for Scotchkote Liner 2400 is similar to epoxy lining process or a CML process. The major difference on this project was that the entire line was reinstated each evening to restore water to the residents eliminating the need for bypass piping. After excavation, the upstream valve is closed, a 4-to 6-ft section of the exposed pipe is removed and the pipe is dewatered. After dewatering, the pipe is cleaned via mechanical process. For the Oswego project, a drag scraping method was used, but water jetting, rack feed boring and other process have been used in conjunction with this product. The choice of cleaning method should match the pipe diameter, length and severity of tuberculation.

After the primary cleaning process is complete, a series of swabs are used to remove any remaining debris or standing water from the pipe. A full inspection follows the cleaning process with a robotic CCTV camera. After successful inspection the lining process is started. The equipment is positioned near on access pit and a winch truck is positioned at the opposite end of the section to be lined. The umbilical is winched into the water main until it reaches the opposite end. At that point a centrifugal spray head is attached (see figure 1) to the end of the umbilical and the equipment is started. After a short “spin up” process the application head is launched into the pipe and the equipment lines the main as it retrieves the extended umbilical. All equipment used in the lining process was designed and built by 3M specifically to work with this product.
During the lining process the system is designed to run nearly autonomously. Upon completion, the lining head is retrieved and the equipment is shut down. Immediately the post lining inspection process can begin and any blocked service connections are opened with a robotic cutter/camera system. The pipe may then disinfected and reinstated. Most rapid set polyurea lining solutions require a minimal one-hour cure before water may be introduced for disinfection and reinstatement but this should be validated with the lining manufacturer and the product’s NSF/ANSI 61(or country-specific regulatory approval) listing should be referenced.

With the exception of moving equipment from pit to pit, the city was able to maintain one lane of traffic throughout the entire project (see figure 2)

One of the key success factors in Oswego was precision coordination of activities. The excavation was completed ahead of time allowing for other critical procedures to be completed on time. The excavations, disinfection and reinstatement tasks were done by the Oswego Water Department. This enabled the cleaning and lining crews to get an early start each morning and enough time to complete the work by 5 p.m. Out of the five lining sections, all were completed by 5 p.m. with the exception of one section which was completed by 6 p.m. due to camera/cutter issues.

By working diligently with all functions, this project was very successful and provided the result that the City of Oswego was expecting (see Figure 3 for before and after installation pictures)

Chad Carney is U.S. business manager at 3M Water Infrastructure.

At prescribed calipers (lining thickness) and bury depths, Scotchkote Liner 2400 is projected to meet material properties of ASTM F1216-09 after 50 years. 3M used the following test methods to validate: ASTM D638-08, ASTM D790-07, ASTM D2990-08 and ASTM D1599-99