Understanding Randle Reef

Hamilton Harbour is home to the largest and
most contaminated site within the Canadian
side of the Great Lakes – Randle Reef.

Hamilton Harbour, also known as Burlington Bay, lies at the western tip of Lake Ontario, and is separated naturally from the lake by a sandbar. It is the largest naturally protected harbour on western Lake Ontario. Industry, commerce and residential areas, along with private and public open spaces share the 45 kilometre shoreline. The Harbour’s watershed covers more than 500 square kilometres and is drained by three major tributaries - the Grindstone, Spencer and Red Hill creeks. The cities of Hamilton and Burlington, with a population of 750,000 people, are located within and around the watershed. In 1985, the Harbour was identified as an Area of Concern under the Canada–United States Great Lakes Water Quality Agreement due to significant impairment of water quality. While many improvements have been made to reduce pollution in the Harbour, the problem of contaminated sediment remains.

Located in the southwest corner of Hamilton Habour, the Randle Reef site is approximately 60 hectares (120 football fields) in size. The site contains approximately 695,000 cubic meters of sediment contaminated with polycyclic aromatic hydrocarbons (PAH) and other toxic chemicals - the largest PAH-contaminated sediment site on the Canadian Great Lakes. The contamination is often described as “a spill in slow motion” due to the continuing slow spread of contaminants across the Harbour floor and uptake into the food chain of the Harbour ecosystem. PAH contamination at Randle Reef is a legacy of a variety of past industrial processes dating back to the 1800s. There were multiple sources of contamination including coal gasification, petroleum refining, steel making, municipal waste, sewage and overland drainage.

The site was identified as a principal target of Harbour restoration objectives in the late 1980s and early 1990s. Studies were conducted over several years to determine possible options for cleaning up the site. In 2002, a Project Advisory Group reached an agreement to explore the idea of containing and capping the sediment. An environmental assessment, project designs, and the quest to secure funding soon followed.

The Randle Reef sediment remediation project involves constructing a 6.2 hectare engineered containment facility (ECF) on top of a portion of the most contaminated sediment, then dredging and placing the remaining contaminated sediment in the facility. The facility will be made of double steel sheet pile walls with the outer walls being driven to depths of up to 24 metres into the underlying sediment. The inner and outer walls will be sealed creating an impermeable barrier. The sediment will then be covered by a multi-layered environmental cap.

The estimated cost of the Randle Reef sediment remediation project is $138.9-million. In addition to the $46.3-million in funding from both the federal and Ontario governments, $14-million is being contributed by the City of Hamilton, $14-million by U. S. Steel Canada and $14-million by the Hamilton Port Authority, as well as $2.3-million from the City of Burlington and $2-million from Halton Region.

Cleaning up Randle Reef is one of the most significant steps remaining to remediate Hamilton Harbour and remove it from the list of Areas of Concern. The project will reduce the amount and spread of contaminants through the Harbour, significantly improving water quality and fish and wildlife habitat. The Harbour will also experience economic and social benefits: enhancement of shipping and port facilities, increased recreational opportunities and the promotion of the Harbour community as a clean and progressive place to live and work.

Construction will progress in several stages:

1. Double steel sheet pile walls are installed to create the perimeter of the ECF structure. These structures will be built prior to dredging activities; the outer wall providing structural stability and the inner wall providing isolation of the contaminated sediment from the surrounding Harbour environment. The interlocks between sheet piles on the inner wall will be sealed creating an impermeable barrier.
2. The sediment between the EFC inner and outer walls is mechanically dredged with sediment disposal inside the ECF. Any remaining sediment is removed using a high solids pump. The space between the walls is filled with clean crushed rock.
3. Production dredging (of sediment beyond the footprint of ECF) begins using a cutter suction hydraulic dredge. The dredge makes two passes along the bottom of the Harbour to reduce the possibility leaving behind contaminants. Any areas that exceed a predetermined PAH value after two passes are covered by a thin layer of sand. A discharge pipeline carries the newly dredged sediment from the dredge pump into the EFC. The pipeline carrying the sediment is submerged in the EFC to reduce the possibility of toxins transferring from the sediment to the air. It is anticipated that the facility will reach capacity before all the contaminated sediment is dredged. However, at this point 99.7% of the contaminant is removed.
4. The sediment inside the EFC is dewatered through gravity and polymer- assisted settling.
5. The removed water is treated by an on-site water treatment system using sand filtration and granular activated adsorption. Treated water is safely discharged into Hamilton Harbour.

Randle Reef Resources

Review the articles below for all of the latest Randle Reef resources.