Epoxy Coatings Key to Major Rehab Siphon Project
This story begins with a multi-million-dollar investment to update a large national event center and its surrounding campus, home to years of tradition in the western United States. Serving as a major historical center of agricultural business in the West since the 20th century, the venue needed a revamp to update the campus’ grounds and preserve its unique history.
In 2019, a major contract was issued to invest in the center’s grounds with new infrastructure and a substantial amount of utility work to update the facility for the future. The owner began the overhaul of the area by awarding the project to a general contractor and lead engineer team with multiple trade subcontractors to update the existing grounds with associated infrastructure and utility improvements with the construction of a new 2.2 million sq ft campus fit for year-round events.
This project included associated pipelines, manholes and epoxy coatings to support the relocation of the interceptor inlet structure. Part of the utility package included relocating two 72-in. above-grade sewer mains into a single, buried 72-in. fiberglass reinforced polymer mortar (FRMP) line for a total length of 2,300 ft with the installation and coating of associated manholes. The project also included the installation of a 66-in. fiberglass gravity sewer pipe, a 43 million gallon per day (MGD) gravity bypass system, and an additional 38 MGD bypass pumping system to move the wastewater flows around the work area for two weeks.
Epoxy Coatings Selected
The third-tier subcontractor, Garney Construction, was contacted to complete the sewer replacement based on qualifications. Due to the amount of new construction and the number of contractors onsite, Garney’s portion of the project had a tight schedule and limited work area to keep the parent project on track. Garney partnered with a trusted coatings contractor with a proven product that had been historically listed in the owner’s specification — A&W Coatings (A&W) with Warren Environmental’s 100 percent solids, high build epoxy system.
A&W was contracted to complete the surface preparation and epoxy coatings application in the new manholes and structures included within Garney’s bid package. The scope included five 72-in. manholes, three 120-in. manholes, one 16-ft by 13.6-ft by 12.15-ft siphon structure, along with an emergency change order scope for the 66-in. siphon crown repairs, detailed later in this article.
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A&W performed surface preparation on the structures to achieve the required surface profile and followed by lining the assets with 125 mils of Warren’s 301-14-1 epoxy — all manholes were new precast concrete structures with t-bases. Coating the new manholes with Warren’s epoxy would protect the structures from future corrosion and extend their service life. A&W’s scope was successfully completed on time, key to maintaining Garney’s schedule.
Coordination and Logistics
The site presented its fair share of logistical challenges. The site was located in the City’s highly trafficked industrial sector and cornered between a major highway and a river. As a result, site access was limited. Although it was large and widespread, all trades, site visitors and material deliveries passed through two entry points each day.
The highly congested site was constantly evolving — with eight different trades and at least half a dozen contractors trades working simultaneously at any given time, coordinating scopes of work was essential to keep the parent project on schedule. As a prime example, A&W coordinated the work with the prime contractor to ensure their slab was installed prior to A&W beginning its siphon crown repairs that night.
Problem-solving an Emergency Pipe Repair
While working on the coatings scope for the manhole structures, A&W received a phone call from the owner soliciting their services to perform emergency work on the same site. With just three days’ notice, the owner issued an emergency change order. The owner contracted A&W to repair a section of the siphon pipe crown, which is concretereinforced encased and to provide protection to the pipe and the reinforced concrete encasement surrounding the pipe with Warren’s epoxy coatings. Due to prior schedule obligations, the section of the 66-in. siphon pipe needed to be made available to A&W no later than the morning of April 23, 2021. The work was to be completed within a three-day window. To maintain this critical schedule, A&W completed the repairs in two nightshift.
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A&W provided the labor, materials and equipment required to repair 40 lf of the concrete crown in the existing concrete reinforced encased 66-in. siphon running under the river. Prior to epoxy application, the crew performed surface preparation on the pipe, removing degraded concrete via water blast. The heavy solids found in the bottom of the pipe were also cleared. Following surface preparation, A&W repaired the pipe by applying approximately 3 in. of Warren’s 301-14 epoxy mastic with aggregate to the 40-lf section of the crown. Serving as Warren’s thickest viscosity product, the 301-14 epoxy mastic provided structural enhancement to the pipe crown. The pipe was top-coated with 250 mils of 301-14 epoxy from the spring line upward, or at approximately nine and three o’clock. By repairing the structure with variations of the same epoxy system, each application works into each other without worrying about its compatibility. This creates a monolithic interior surface that makes the structure stronger while preventing further corrosion or groundwater infiltration.
The siphon crown emergency repairs were completed successfully as a result of the epoxy’s performance and A&W’s high-quality application. The A&W crew cleaned the pipe via water blasting in the surface preparation phase, but the pipe was not completely dry in the damp and cold environment. This was critical to the project’s timeliness because Warren’s epoxy could be effectively applied to the surface where moisture and standing water in the bottom of the pipe were still present — a characteristic that is not true with all coatings solutions.
Project Successes
Timely coordination with the owner, engineer, and subcontractors on-site, plus the ease of application of Warren’s epoxy system allowed A&W to successfully complete the original scope of work and the unplanned emergency siphon crown repair. Key relationships and the crew’s preparedness to problem solve ensured a successful project turnout. As a result, the owner’s new sewer assets will be protected from corrosives for years to come.
Hunter Sansone is a project engineer with A&W Coatings.
