Numerous systems and strategies may be utilized to provide secondary containment for the storage of petroleum-based products, wastes, and other polluting materials. ITC wanted to consider technologies that would hold oil products within containments and within their property before developing secondary containment and stormwater management engineering standards. ITC hired ECT to test several technologies under a range of circumstances, including controls that allow stormwater to discharge off-site, but stop flow when the stormwater contains oil.
ECT designed the testing to address the following:
- Could the device contain a catastrophic release?
- Could the device contain a sheen?
- How much oil is required to trigger flow shut-off?
- How much hydraulic head was required for the device to operate correctly?
- What flowrates could be achieved?
- How quickly does the device react to oil?
- What are the maintenance concerns for each device?
ECT tested various devices containing oil-solidifying polymers under controlled conditions within specially designed test chambers. The devices that use conductivity changes to stop flow were tested in situ at ITC substations where they had already been installed. The team plugged discharge outlets and cleanup contractors were onsite during testing. ECT tested devices that use cross-linking polymer beads imbedded in a filter material. The polymers allow water to pass through, but they absorb any oil and swell, preventing any further flow of water or oil. ECT also tested oil stop valve devices that utilize the specific gravity difference between oil and water to trigger the closure of a valve. These devices allow water to pass through, but the sump valve closes stopping all flow when sufficient oil is present. ECT tested devices that utilize a conductivity probe to detect oil and turn off the associated sump pump system. Oil does not conduct electricity; thus, when oil comes in contact with the probe the sump pump is turned off and alarms are sent.
The testing provided valuable information on the performance of each control device. The technologies proved to be effective methods of preventing a catastrophic oil loss and providing secondary containment. The results allowed ITC and ECT to make decisions on where and how to use each type of device. In cases where ECT identified opportunities for improvement, the information was communicated to the manufacturer. The general findings will be included in the Guide for Containment and Control of Oil Spills in Substations (IEEE P980).