Lift Station Wet Well Rebuild

The challenge

A sewage lift station wet well takes attack from two directions at once. The walls and benching sit under immersion in raw flow, while above the waterline the hydrogen sulfide gas coming off the sewage turns to acid on the damp concrete and eats it away. The surfaces softened and lost concrete, the embedded rebar became exposed and started to corrode, and the benching that channels flow toward the pumps wore out of shape. Left untreated, a wet well keeps losing structure until it can no longer hold the flow or guide it to the pumps, and the station risks an overflow.

Our approach

We bring the well down and clean out the loose, softened concrete back to a solid base, then clean the exposed rebar and treat it so it stops corroding. We rebuild the walls and reform the benching with a cold-applied repair mortar, bringing the surfaces back to profile and shaping the benching so the flow runs to the pumps the way it should. Once the substrate is sound, we line the whole interior against the corrosive sewage and the acid gas above the waterline, so one continuous barrier protects the steel and the new mortar from the attack that wore the well down in the first place.

1. Assess and clean outWe survey the wet well to map where immersion and acid gas have softened the walls and benching and where the rebar is exposed.
2. Remove and prepWe break out the unsound concrete back to a solid substrate and clean the exposed rebar to a sound condition.
3. Repassivate and rebuildWe treat the steel to repassivate it, then rebuild the walls and reform the benching with a cold-applied repair mortar.
4. Line against the flowWe line the interior with a system keyed to the corrosive sewage and the acid gas above the waterline as one continuous barrier.
5. Return to serviceWe confirm the rebuilt and lined surfaces are sound and turn the wet well back over for return to service.