A large power generation facility in Calgary, Alberta experienced leaks due to corrosion in the leak detection sample line for one of the underground contaminated fluid containment tanks that was below a twelve (12) inch thick structural concrete slab. Revive Pipes saved the facility over $50,000 when we removed tuberculation buildup and installed a Cured in Place Pipe (CIPP) structural liner inside of the leak detection sample line.
The power generation facility had several double walled contaminated fluid tanks under the thick, structural concrete slab in the facility. The tanks are designed so that the inner tank holds the contaminated fluid. If a leak occurs in the containment tank, the contaminated fluid flows into the secondary containment tank that is attached to a vertical leak detection sample pipe that runs up through the floor. If fluid enters the secondary containment tank, it fills up the leak detection sample line, which lifts a float sensor in the sample line and sounds an alarm in the control room. The tank can be removed and repaired before any contaminated fluids leak into the ground with this arrangement.
Holes due to corrosion occurred in the containment tank leak detection sample line. The high water table in the area around the power generation facility allowed for water to flow through holes and fill up the sample line. This caused the leak detection system to indicate an alarm, even though the primary containment tank was not leaking. Tuberculation deposits built up in the sample line and caused the float switch to become lodged in the sample line. When operators attempted to remove the stuck float switch by pulling on the sensor cable that ran up to the floor level, the sensor cable pulled out of the float switch. The switch was left trapped fourteen (14) feet below floor level in the sample line.
The facility was faced with an extremely costly and disruptive sample line replacement that would have included:
- Engineering consultation to cut through the structural slab
- Saw cutting of the twelve (12) inch thick concrete slab
- Excavating fourteen (14) feet down to the bottom of the sample line, which would have been extremely challenging and required significant dewatering operations due to the areas high water table.
- Shoring of the excavation walls for safety and to prevent the wet soil from collapsing into the excavation.
- Removal and replacement of the corroded leak detection sample pipe.
- Refilling and compacting of the excavated pit.
- Pouring new twelve (12) inch thick structural slab and tying it into the existing structural slab with rebar.
Revive Pipes specialized services provided the power generation facility with a substantially more cost effective and non-invasive solution. First, we bored out the tuberculation above the float switch. We then custom designed and fabricated a tool that threaded into the sample switch and extracted it from the pipe. After boring out the corrosion in the remainder of the sample line, we installed a Cured in Place Pipe (CIPP) structural liner inside of the leak detection line.
Operators installed a new float sensor and sensor cable and reinserted them into the leak detection sample line. The double walled containment system now functions properly and without groundwater filling up the sample line, operators are able to determine if there is a leak in the primary containment tank. Primary containment tank leaks can now be repaired before contaminated fluids are able to flow out of the system and contaminate the soil.
Economic Impact: $50,000 Cost Savings
Facility Impact: 0 Excavations Required
Contractor Time on Site: Reduced by 95%