Liverpool, Pa., Tackles Overflow Discharge Pipe Rehab at Lake Heron
Liverpool, Pennsylvania, is a small borough located on the Susquehanna River about 30 miles north of the state capital of Harrisburg. Originally settled in 1808, Liverpool served as a hub of business activity for the Pennsylvania canal through the 1800s.
Today, U.S. Routes 11 and 15 have replaced the canal as the major north-south transportation artery. Liverpool is a small town, home to many historic buildings. It offers recreation opportunities that include world class bass fishing in the Susquehanna River, easy access to Little Buffalo State Park, hiking, camping, canoeing and skiing.
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In addition, the borough is largely dependent on Lake Heron, a nearby lake, for its water supply. The town recently tackled a needed infrastructure repair that first seemed like a small issue several years ago but turned more severe, especially considering the impact on recreational activities on the lake.
Lake Heron’s overflow pipe, located on the edge of the lake, had deteriorated well past the many flow points located along its length. In order to fix this, a corrosion barrier that was structural in nature was needed.
The corrugated pipe measured 20 ft deep and 42 in. in diameter. This would make spray access easier, but the depth made it a nightmare for dealing with water. With the average annual temperature of 27.6 F during this time of the year, snow and freezing temperatures would also be troubleshooting factors.
As if that wasn’t enough, weather entered the picture in the fact that the lake was completely covered with thick ice, except around the edges. Since it was January, most of the region’s lakes had frozen over. However, the ice would now have to be counted on to support the significant weight of the bridge technicians would need to build to reach the pipe. Upon testing, the crew needed to ensure that the bridge would hold before proceeding to set up safety equipment.
Two factors often overlooked in the coatings world are water and climate. This project included a considerable measure of both. Since the pipe was situated in the lake, water was the primary issue and had to be shut out before the project could proceed. This was accomplished by stopping the infiltration with a chemical grout pumped into the openings, then using a blower to dry the structure.
To rehabilitate the overflow pipe, the town turned to Sprayroq, a designer and manufacturer of spray-applied polyurethane technology for infrastructure rehabilitation and protection. Abel Recon, a Sprayroq certified partner, served as the contractor for the work.
For the rehabilitation, the project team leveraged Sprayroq’s SprayWall, a structural, spray-applied polyurethane-based product with a compressive strength of more than 18,000 psi. According to Sprayroq, SprayWall has a 50-year design life and is 43 percent stronger than concrete. It has also been approved for use in potable water applications (NSF 61 certified) and as well as use in infiltration control, high hydrostatic loading and structural reinstatement of deteriorated water structures.
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Sprayroq utilizes ASTM F1216 to design the thickness required to rehabilitate a circular structure. In this particular case, the algorithm associated with the ASTM standard was used to arrive at the thickness needed for this pipe.
“We utilize this same algorithm for nearly all circular structures,” says Sprayroq director of business development Jeremy Huckaby. “In addition, for flat wall structures, we utilize a third-party algorithm that was designed for us by a third-party structural engineering firm and utilize it to calculate the required thickness for flat wall applications, such as a lift station or a box culvert.”
SprayWall is a self-priming polyurethane lining that reinstates structural integrity, provides infiltration control and chemical resistance. It may be applied up to 250 mils (0.25-in.) /6.35 mm thick in a single application. SprayWall begins to gel in about 8 seconds, with a tack-free condition after two minutes. The product is sprayed using a proprietary heated plural component spray system and is applied at around 120 degrees F, Sprayroq’s recommended temperature for optimum protection. Once applied, SprayWall achieves a tack-free condition in one minute. Within 60 minutes, the initial cure is complete and the structure is capable of accepting flow, while complete curing continues over the next 72 hours.
“SprayWall has grown in its popularity over the past decade especially in high groundwater table environments,” says Huckaby. “Engineers and asset owners alike are pleased with the fast return to service that SprayWall provides along with the structural nature of the product.”
SprayWall’s quick curing time (potable water applications require greater cure time) allows the newly protected structure to be returned to service shortly after the application is completed, making it ideal for use on water, wastewater and stormwater rehabilitation, and on DOT projects, when keeping flow and traffic disruption to a minimum is critical.
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Lake Heron Solution
After water and climate issues were out of the way, the project team began to prep the structure and get ready for the spray application. The pipe required a thickness of 300 mils or a little more than ¼-in. of SprayWall to give the structure the corrosion barrier and structural protection it needed.
“The project was challenging because of the depth and extensive amount of active infiltration,” says Huckaby. “Ultimately, it was successful because the infiltration was resolved and the structural integrity of the pipe was restored with SprayWall.”
The project took two days and used 1,100 lbs. of SprayWall material and the town was able to return the lake to regular recreational use as soon as the ice thawed.
“We’ve found that customers enjoy having the peace of mind that comes with our products being distributed only to contractors who have received extensive training from Sprayroq.
“In the end, they know that they are receiving a great product and a professional applicator because of Sprayroq’s comprehensive third-party testing and the in-depth certification process employed with the contractors.”
Andrew Farr is an associate editor of Trenchless Technology.