Environmental safety is a big reason why Millennium does the work we do. Here on the Gulf Coast, our water tables are very close the surface. When concrete, a porous material, is set below the water tables, passage of fluids like water, or anything less viscous, can certainly happen. With no head pressure inside the tank, the infiltration of water to the negative pressure side of the wall is all the evidence necessary to demonstrate the need for appropriate liners. The original use of this tank was as a raw water clarifier, permitting nature to settle down (dirt, etc); however, when chemicals were going to be introduced to accelerate the water filtration and purifying process, a liner needed to be applied to protect the environment from those materials. Here, after plugging all of the leaks, a fiberglass reinforced Semstone liner was applied by roller and trowel. Due to the smooth surfaces and expected life of the liner, this clarifier should be easy to clean annually, and a multi-decade expected life.