Environmental Stewardship – Rokeby Generating Station

Fuel system upgrade minimizes the possibility of an oil leak

Rokeby Generating Station
Lincoln Electric System 

Challenge. The original Rokeby 1 GE 7B combustion turbine was installed as a fuel-oil-fired unit in 1975. Unit 1 was the first of three combustion turbines installed at the Rokeby site. With the installation of Units 2 and 3, their fuel oil systems included double-walled pipe with remotely monitored leak detection.

   In 2007, as part of a fuel-oil-storage containment improvement project, the section of fuel-oil lines running from the 2-million-gal storage tank to the Unit 1 fuel-forwarding skid was replaced with double-walled, monitored pipe.

   This left one section of the unit’s fuel-oil system with the original 37-year-old direct-buried piping and fuel-skid components. These fuel system components represented a substandard section in the site’s fuel oil system and presented higher risk for a fuel-spill incident.

Solution. In order to reduce the opportunity for an environmental incident, the last portion of the fuel-oil system was upgraded to meet the standards of the rest of the site. The fuel-forwarding skid-upgrade project included the following:

  • Replacing the last 20-ft section of underground carbon steel fuel pipe with double-walled, fiberglass pipe equipped with electronic hydrocarbon leak detection
  • Adding a fuel-spill containment structure under the fuel-forwarding skid
  • Upgrading fuel-skid components, including: replacing every bolt and gasket on all flanged connections; replacing all butterfly valves, relief valves, and associated piping; extending drains for the fuel-oil heaters to the front of the skid for easier access; and rerouting 1-in. return piping through the skid for easier interface with generator piping (Fig 8).

Results. The decision to replace this last section of the fuel-oil pipe turned out to be more timely than originally envisioned. When the old pipe was excavated for removal it was discovered that a large section of the pipe had not been treated with the OEM’s corrosion inhibiting material (allowing it to be in direct contact with the soil since 1975). 

   The pipe’s integrity was still good and no oil was spilled. However, there was some contaminated soil removed from under the fuel forwarding skid when the new containment structure was constructed.

   The new section of double-walled pipe was “mapped” into the site’s fuel-oil leak-monitoring system, providing 100% coverage for the site’s fuel-piping system. The spill containment structure installed for the fuel-forwarding/heating skid allows for storage of up to 2400 gal of fuel oil.

   A remotely monitored fuel-oil leak detection system was also installed in the containment structure. The improvements will significantly reduce the risk of a fuel-oil spill caused by failure of a component on the forwarding skid or degradation of buried pipe.