Esquimalt Graving Dock Adopts
Oil-Spill Avoidance Technology

The Esquimalt Graving Dock (EGD) – a branch of Public Works and Government Services Canada (PWGSC), a Canadian federal government department - is the largest solid-bottom commercial drydock on the West Coast of the Americas. Located just outside of Victoria, Canada the facility is able to accommodate multiple ships at any one time and has a total length of 361m.

EGD is one of only three multi-user ship repair facilities in the world with ISO 14001 environmental certification. Improvements in oil spill detection and response were identified as an area of critical interest in the year 2000, as EGD prepared for ISO certification. At the time, the dry-dock used visual inspection procedures to detect oil spills. Visual inspection required all staff to report any slicks or oil spills that were seen, which proved difficult at night or in rough weather.

The facility decided to replace visual inspection with a technology alternative, one capable of detecting spills earlier and more reliably. Key functionality – including 24-hour real-time monitoring,  reliability in rough weather conditions, and automated notification capabilities – was identified. Frequency of maintenance was also deemed an important consideration.

Clearly, any solution had to fit within the operational context of the dry-dock. The facility is closed to the sea by way of a floating caisson, ballasted with concrete and seawater. Once a ship enters the facility, the caisson is deployed and pumps are engaged to evacuate water from the dry dock. A tunnel is used to fill and empty the dock; this tunnel connects to separate tunnels enabling each section of the dry-dock to fill or drain independently through culverts in the floor. Water that is pumped out from the floor of the dry-dock is deposited into the ocean via a single outfall, which is separated from the open ocean by an oil spill containment boom.

EGD chose to deploy three Spill-SentryTM oil-on-water sensors and a single base station. The first oil-on-water sensor is deployed in a well that provides vertical access to the primary evacuation and flooding tunnel. Water is allowed to pool in the tunnel to a predetermined depth before the massive pumps are switched on to remove the runoff. As the tunnel gradually fills, the Spill-SentryTM floats upwards on a ladder-like deployment frame. When the pumps go on to empty the tunnel, the Spill Sentry drops with the water until it rests on the concrete bottom. Prior to planned flooding of the dry-dock via the tunnel – an exercise that sees massive volumes of water enter the tunnel, thus generating significant shear forces - the Spill-SentryTM is winched upwards.

Deployment of the first Spill-SentryTM in the tunnel enables the EGD to detect spills before they are pumped out to the environment via the outfall. The second sensor is deployed on the containment boom that separates the outfall from the open ocean. Should hydrocarbons pass through the tunnel and escape via the outfall, the boom sensor acts as a second line of defence. Hydrocarbons detected in this area remain in a contained environment and have not yet entered open water. As a result, clean-up is easily implemented.

The boom sensor is solar powered and uses radio communications. Detection data is communicated to a single base station located in the control room. The third and final sensor is deployed on the south side of the facility, and monitors hydrocarbon release from the many industrial facilities that neighbour the Esquimalt Graving Dock.

The Esquimalt Graving Dock is located less than 40km from the Applied Microsystems’ factory. As a result, Applied Microsystems provides both technology and services to the facility. The original deployment saw Applied Microsystems build and assist in the installation of the three-sensor system. Subsequently, the company has taken on responsibility for ongoing maintenance and support of the early warning system.

For additional information on this project – or similar oil spill sensor projects - please contact sales@AppliedMicrosystems.com