A major refining company in Texas had a subsurface reinforced concrete sulfur pit that began to experience degradation when water started to enter the pit through cracks in the concrete walls. The ingress of groundwater into sulfur pits creates a serious concern because as it mixes with the molten sulfur, sulfurous acid compounds that are extremely damaging to concrete are formed.

STRUCTURAL was contracted to perform a condition survey and evaluation. During the evaluation, crews discovered that the sulfur pit had extensive deterioration along the walls and immediate structural repairs were required.

STRUCTURAL and the owner worked closely to create a repair strategy that would last longer than previous repairs. While their initial plan was to line the pit with a stainless steel plate, the owner opted to implement STRUCTURAL’s  proven solution of constructing an engineered structural liner that incorporated extremely durable materials such as embedded reinforcing, mechanical anchorage and construction joint waterstops. In essence, this solution creates a new "pit within a pit." This option cost substantially less than the stainless steel plate and would avoid the problems commonly associated with this solution.

The sulfur pit was 15 feet wide 50 feet in length with an average depth of 15 feet. Before the project began, extensive preplanning was conducted with the owner to address logistical concerns such as confined space, hydrogen sulfide gas and the heat of the Texas sun. To combat the extreme heat, industrial air conditioners were brought in, and cold air was circulated into the pits with fans.

Because this was a short duration outage, STRUCTURAL crews worked around the clock, met the two-week schedule and provided the owner with a long-term solution to a commonly misunderstood root-cause deterioration mechanism.