EDT was asked to review the construction of a multimillion-dollar addition to a food processing facility and to determine the cause of water penetration through the floors of the facility.
EDT Analysis and Findings:
After a multimillion-dollar addition to a food processing facility was completed and the facility began operation, water began to penetrate the floors of the facility, resulting in water dripping from the upper floors onto the processing lines. After multiple failed attempts to determine the cause of the water penetration of the floors, FDA inspectors stopped the operations in the addition to prevent contamination of the food product on the affected lines. The owners of the facility filed suit against the engineering firm that designed the addition and against the general contractor who constructed the facility. The general contractor then filed suit against a portion of the sub-contractors involved with the construction of the floors.
The construction of the floors consisted of pre-cast concrete slabs with a cast in place concrete topping slab. A roofing membrane was placed over the lower topping slab, with a second, upper topping slab cast over the membrane. A topping consisting of an epoxy material was then installed as a wearing surface to protect the system from damage due to wheeled traffic. Process water and water from the sanitation process was intended to penetrate the wearing surface and the upper topping slab and be collected on the membrane. Water on the membrane would then drain from the surface of the membrane into the body of floor drains through weep holes in the drains.
The majority of the water problems were reported to be occurring when the sanitation crew cleaned the processing equipment each night. An inspection of the facility during the time the sanitation crew was working showed that each piece of equipment was flushed with water nightly. Piping was attached to a discharge flange on each piece of equipment, with the opposite end of the piping attached to a flange for drainage piping in the floor. Water with various cleaning chemicals was then pumped into each piece of equipment, with the water circulating through the equipment and out the discharge flange. The surface of each piece of equipment was then sprayed with water containing various cleaning chemicals. The inspection showed that on multiple pieces of equipment, water backed up in the equipment and flowed onto the floors instead of out of the flanges of the drainage system when water was pumped into the equipment, with a large volume of water collecting on the floors. The size and configuration of the drainage piping was documented, along with the pressure of the water pumped out of each piece of equipment. During the inspection, EDT obtained information for each of the chemicals used in the sanitation process.
Destructive testing of the floor system was conducted. The floor system was cut and disassembled in multiple locations to allow for an inspection of the materials and methods used in the construction of the system. When the roofing membrane was exposed, multiple holes in the membrane were observed. It was also observed that the lap joints of the membrane were not fully bonded in some locations. In addition, the weep holes intended to allow water to flow from the membrane and into the floor drains had been sealed with caulk. After the inspections were complete, an engineering firm working on behalf of the design firm produced a report that concluded the water problems at the facility were a result of faulty installation of the membrane by the sub-contractor responsible for the work.
A review of the design documents showed that the membrane used in the floor system was marketed as a roofing membrane. Documentation from the manufacturer of the membrane contained no information regarding the use of the product in a floor system. EDT sent a listing of the chemicals used in the sanitation process to the manufacturer of the membrane and asked what effect the chemicals would have on the membrane. The manufacturer responded that one of the chemicals, at low concentrations, was highly corrosive to the adhesive used to bond the lap joints of the membrane. The specification of a product not intended for use in a floor system, and a product that would be damaged by the chemicals used in the sanitation process, was a design defect. An analysis of the piping used in the floor drainage system showed that the piping did not have sufficient capacity to drain the water flushed from the equipment during the cleaning of the equipment. The inadequate sizing of the piping was another design defect.
A review of the records from the construction of the addition showed that the general contractor allowed hot work, such as welding, to take place over the exposed membrane during the installation of the membrane. In multiple locations, the documents showed that the membrane was damaged by hot material falling on the membrane. Allowing hot work over the exposed membrane was a construction defect that resulted in holes in the membrane.