April 26, 2022

Cracked Riser Pipes Repaired with Carbon Fiber

HJ3's patented CarbonSeal carbon fiber repairs corroded, cracked riser pipes for a fraction of the cost of replacement.

Addressing Leaking Pipes in Duke Energy Facilities to Prevent Coal Ash Spills

The recent coal ash spill caused by Duke Energy, which resulted in more than 70 miles of the Dan River being contaminated by 40,000 tons of toxic coal ash, has prompted the need for immediate inspections and repair plans across all 14 Duke Energy facilities. This includes both operational sites and those that have been retired or demolished. While most inspections have indicated that "the infrastructure is safe and performing as designed," numerous leaks have already been identified in riser pipes and pipelines within these facilities.

The Eden facility, responsible for the coal ash spill, is not the sole location with leaks; Duke's Weatherspoon Steam Electric Power Plant, although retired in 2011 and demolished in 2013, still features a 54-acre coal ash pond with a cracked riser still in use. The steel-lined concrete riser's purpose is to siphon the cleanest water from the pond's surface when water levels rise, enabling heavier sediment and coal ash to settle at the bottom. While experts consider a coal ash leak of the scale witnessed in Eden to be improbable at Weatherspoon, concerns remain about the crack potentially leading to the release of ash-laden water into local tributaries and rivers. It's essential to remember that coal ash contains toxic substances, including mercury, cadmium, lead, arsenic, selenium, chromium, among others.

Duke Energy has been granted a deadline of July 20 to provide a repair schedule. Failure to do so could result in fines of up to $500 per day.

The identified leaking crack in Weatherspoon's riser pipe was discovered through camera inspection, prompting further engineering studies to determine necessary remedial measures. A similar issue was detected at another Duke Energy steam plant, where a 40-foot crack in the coal ash dam at the Cape Fear Steam Electric Plant had developed due to shifting earth beneath the dam. This shift caused a riser in the pond to bend almost to the point of cracking. While Duke Energy has already resolved the issues at the Cape Fear plant, they have yet to present repair plans for the riser at the Weatherspoon plant.

Duke Energy and similar power plants rely on a circulating water system to cool heated steam, which has been processed through a turbine. The condensed steam transforms back into water for reuse in electricity generation. However, the riser pipes responsible for transmitting cooling water are susceptible to corrosion, and corrosion can lead to cracked and leaking pipes.

In the case of a southwestern U.S. power plant, corroded riser pipes had cracked and were leaking. To reinforce these risers, HJ3 used the CarbonSeal™ system. The repair process began with the excavation of the riser pipes and removal of their concrete diapers. The exposed steel surface was prepared to near-white metal standards and primed. The CarbonSealTM high modulus paste was applied, followed by the installation of saturated CarbonSealTM fabric. An abrasion and UV-resistant topcoat protected the carbon fabric. Steel sleeves were added at the base of the repair area, and the repaired risers were enclosed with new concrete diapers. The client's aesthetics were met by painting the repaired risers.

In total, all 22 steel riser pipes were reinforced within a limited window. The client achieved significant savings, preventing $1 million for each day beyond the scheduled repair that the plant would have been shut down. Additionally, the client saved over 127,000 gallons of water and 17,000 kWh by repairing the risers instead of replacing them. Furthermore, this approach prevented 3 tons of CO2 emissions from polluting the atmosphere and 2.5 tons of steel and concrete waste from ending up in landfills.

If you are dealing with steel risers in need of repair and want to learn more about HJ3's CarbonSealTM reinforcement systems, don't hesitate to reach out to HJ3 at info@hj3.com.

The Weatherspoon Plant was demolished in 2013 but its ash pond is still full
Credit: fayobserver.com

Riser at the Cape Fear Plant's ash pond
Credit: Charlotte Business Journal

Some of the 22 risers needing repair
A corroded riser
The riser is abraded and ready to be primed
The riser is wrapped with saturated CarbonSeal fabric
An installer applies a UV- and abrasion-resistant topcoat


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