A properly designed and maintained drainage system is critical to limiting the spread of fire from an uncontained oil spill – one of the worst disasters that can occur in a turbine building. NFPA 850 devotes a section (Section 6.5 in the 2026 edition) to achieving containment and drainage. Ideally, a properly designed turbine building would include a drainage system capable of collecting and draining the spill of the largest amount of any flammable or combustible liquids in the area, in addition to:
The maximum expected number of fire hose(s) operating for a minimum of 10 minutes
The maximum design discharge of fixed fire suppression systems operating for a minimum of 10 minutes
In short, it's essential to prevent flammable/combustible liquid releases that are possibly on fire from accumulating beneath critical equipment or from flowing into areas that house critical equipment. Containing and draining flammable/combustible liquid limits a fire's fuel, reduces the facility's total thermal impact, and potentially allows for earlier suppression.
Undermining Drains is a Common Problem
AEGIS Loss Control's experience during many site visits has revealed that competing interests frequently impede drainage systems. Some of the most common are:
The Environmental Group doesn't want oil leaving the building.
The oil-water separator can't handle a full release.
Safety personnel find the grating over the trench drains to be a tripping hazard.
Operators desire a smooth path for moving tools and portable equipment.
Washing activities, typically a flow of under 50 GPM, push waste and debris into the drains but don't assure the drainpipe is left clear.
Transportable debris from maintenance and operations work activities remains on the floor, and/or
Sumps are used for the storage of oily water to reduce the frequency and costs of disposal.
These competing interests can result in intentional blockage or slowing of drainage using filters, absorbent pads/pigs, plugs or even sheet metal or diamond plate. Unintentionally, debris can be transported from maintenance and operations work activities, which can inhibit drain flow. Lastly, if the sump is already full or partially full, the flammable/combustible liquid release has nowhere to go, an issue that can be compounded by the flows from operating water-based fire suppression systems. Drains are an integral part of the fire protection system during a large flammable/combustible liquid release event; when they're needed to contain and remove a combustible fluid release, they're needed immediately. Regardless of whether a fire exists, removing the fuel from open exposure needs to occur quickly. A partially or entirely blocked drain is unable to perform this function effectively.
Maintenance Considerations: A case for routine inspection and testing
During an AEGIS Loss Control property risk assessment, a risk-reduction suggestion was made to evaluate the drains' ability to remove liquids effectively. In response, the plant initiated proactive, periodic observations and inspections that included ensuring water did not accumulate on the floor or in the trenches. Upon observing during an inspection that water did not appear to flow as easily as expected, it was determined that there was a restriction in the pipe, and a water blasting contractor was retained to address the blockage. After using ~18,000 psi of water to blast and flush out a solid stone-like material, the flow rate was restored, and the line was visually inspected. Testing verified that the drain was functioning properly to handle the maximum flow rate. In this instance, calcium buildup over time resulted in an obstruction that was not detected until the flow was visually impacted. This is an excellent example of the need for inspection and testing to reveal an issue before it becomes critical. NFPA does not describe a drain test method, but each site should consider what is required to understand whether or not its drains will perform as designed. In existing facilities, answers to the following questions could prevent disaster:
Do we know our floor slopes, trenches and drains are available to handle the highest possible flow? How do we know?
Should we inspect our drains periodically to ensure they remain consistently clear for the length of the system? Should we have a PM to ensure their operation?
Are sumps routinely inspected to ensure they are empty?
Do we have a safe place to contain oil, and for how long?
How quickly can a spill flow to an oil-water separator or be removed by pumping a sump? Is this stated in our SPCC?
For more information on designing and maintaining the drainage systems critical to fire suppression, contact Bob Fetterley, Senior Property Loss Control Professional, by email.
Consideration should be given to periodically inspect, maintain, and test turbine building drainage systems to ensure that they are being maintained in a fully operational condition. For more information on designing and maintaining the drainage systems, contact your AEGIS Loss Control representative.
