Lindberg Pump Station: Averting Disaster at a Wet Well
We all know that concrete cracks. However, when a 30-year-old, pressurized wet well started developing significant leaks, we sprang into action. The condition of the well became critical and waiting longer would further compromise the wet well. After an initial site assessment and review of the record drawings, we developed a two-pronged approach to stop the leaks. The leaks appeared to be coming from a joint between the wall and lid of the wet well. The record drawings did not show a water stop at this joint, and we assumed the joint had weakened over time and started leaking.
El Paso Water has complex operational challenges because of varying water sources. For about six months of the year (April to October), El Paso operates its surface water treatment plants. During the rest of the year, El Paso pumps groundwater. This affected when we could perform work on the wet well. El Paso Water mandated that we begin construction after their peak day in late July but have the wet well back in operation by mid-September. This only gave us a short window to complete the project.
Our two-pronged approach was: 1) inject expansive foam along the exterior of the joint along the areas that are leaking, and 2) coat the interior of the wet well with an elastomeric coating to create a “balloon” on the inside to completely seal the wet well. The expansive foam was injected while the wet well was in service. This stopped the majority of the leaks; however, it did not completely stop all of them. The wet well was taken down and crews started water-blasting the interior to prep the concrete for coating.
During the water blasting, portions of the lid started spalling off. That’s when the project got really interesting. About 60 percent of the lid was very deteriorated, and we had concerns about the structural integrity of the lid. The project team quickly evaluated our options and developed a repair strategy that could get the wet well back in service during the required schedule. We contacted a carbon fiber supplier/installer to work on a solution. They quickly mobilized a crew to chip out the spalled areas and fill them with epoxy. Carbon fiber was then applied over the deteriorated areas to “stitch” across the bad concrete. The carbon fiber provided a structural and water-proof solution.
The coating that was initially planned for the interior was applied over the carbon fiber to provide a water-tight solution, and the project was completed within the very tight schedule.
Mike Ramirez is a Principal and Director of Construction Services for PSC. He has 18 years of engineering experience with an emphasis on large diameter pipelines, pumping facilities, GIS applications, collection and distribution modeling, and planning, design, and construction of water and wastewater projects. Mike has managed the planning, design or construction of over 100 miles of pipeline projects in the past 10 years, ranging from 6 inches to 90 inches.