2010 Symposium ~ IMWA 2010 ~ Mid-Conference Excursion 5 Belinda Campbell, David Forrester. Sydney Tar Ponds and Collieries

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1 ~ IMWA 2010 ~ 2010 Symposium Conference Theme: Mine Water & Innovative Thinking Mid-Conference Excursion 5 Belinda Campbell, David Forrester Sydney Tar Ponds and Collieries International Mine Water Association September 5 9, 2010 Cape Breton University Sydney, Nova Scotia Canada

2 5 SYDNEY TAR PONDS AND COLLIERY TOUR

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4 Sydney, NS Mine Water and Innovative Thinking IMWA 2010 Sydney Tar Ponds and Coke Ovens Site Remediation Project Belinda Campbell, David Forrester The Project Nearly 100 years of steel and coke production left behind more than a million tonnes of contaminated soil and sediment. The contamination spread to four sites around the former steel mill: North and South Tar Ponds Former Coke Ovens property An old dump uphill from the Coke Ovens A stream that carried contaminants from the Coke Ovens to the Tar Ponds Figure 1 Construction Elements Cooling Pond The former cooling pond is now a small, circular piece of property adjacent to the south tar pond. As the grass grows, the former cooling pond will disappear into the landscape. The Cooling Pond project was completed in the spring of The old circular reservoir, built in 1912 to hold water once used in the steelmaking process at SYSCO, has virtually disappeared. The $4 million project began by de-watering 3 million gallons, about 250,000 gallons daily, out of the cooling pond to expose sludge (about 1.5 metres deep) spread along the bottom of the structure. The water was pumped to a permitted facility on the former SYSCO site for treatment. Once treated, the water was properly discharged. The sediment was impacted by Total Petroleum Hydrocarbons (TPHs), Volatile Organic Compounds (VOCs), Polycyclic Aromatic Hydrocarbons (PAHs), and metals. In mid - December, contractors started to Solidify and Stabilize the sludge, starting with a pilot-scale demonstration, followed by full-scale Solidification and Stabilization. Mid Conference Excursion 5 3

5 IMWA 2010 Mine Water and Innovative Thinking Sydney, NS Existing structures, such as old piping and a pump house, were decommissioned and removed from the site. Throughout the activities, the Sydney Tar Ponds Agency continued with its commitment to protect the community and the environment. The project had a comprehensive environmental management plan that included an extensive air-monitoring program and dust and odour controls. There was also a master health and safety plan to protect workers on site, and the health and safety of the public continues to be of prime importance to the Agency. The cooling pond project was Nova Scotia s first aboriginal set-aside. The project provided bidders with majority aboriginal ownership and control the opportunity to benefit from cleanup work and to gain skills and training needed to compete for other construction projects. Coke Ovens Brook (CO1) Coke Ovens Brook Connector discharges into the South Tar Pond and includes the lower portion of the Coke Ovens Brook closest to the Tar Ponds. This brook was the primary pathway for contaminants that migrated from the Coke Ovens Site and into the Tar Ponds. As a result, stream sediments have been impacted by organic and inorganic contaminants. The remedial approach for the connector is to remove impacted sediments and reconstruct the channel. The reconstructed channel will be isolated by installing a liner in the channel bed and backfilling with riprap. Rip rap is rock or other material commonly used to protect shorelines, streambeds, bridge abutments and other shoreline structures against scour, water or ice erosion. Construction of this element is required prior to connecting Coke Oven Brook with the commissioned Coke Oven and Wash Brook Channels. Prior to completing construction of the connector, the Coke Ovens Groundwater Collection System and Water Treatment Plant will need to be completed because they are located upstream of Coke Ovens Brook. Figure 2 4 Mid Conference Excursion 5

6 Sydney, NS Mine Water and Innovative Thinking IMWA 2010 Tar Cell Solidification/Stabilization (CO2) Approximately 25,000 tonnes of PAH-impacted soil has been remediated at the northwest corner of the site using the process of Solidification and Stabilization. Cutoff Walls (CO5) The vertical Cutoff Walls on the Coke Ovens site are intended to work in conjunction with other design elements of the overall remedial approach, including the Coke Ovens Surface Cap, the Coke Ovens interceptor line, and a water treatment plant. The cutoff walls will serve to control the movement of clean and contaminated groundwater over the coke ovens site. Two cutoff walls have been designed; one across the north side of the Coke Ovens site and one on the south and west sides. The walls are made up of a combination of bentonite slurry (mudlike material) and low permeability soil for areas of changing topography or shallow excavation. Surface Cap (CO6) The purpose of the Surface Cap is to prevent outside influences from coming in contact with contaminated soil, and to allow for revegetation at the Coke Ovens site. Capping at the site can begin in areas where other remedial activities are not planned. Long-term monitoring of the cap is planned to ensure that the barrier s integrity is maintained. Collection System (CO7) / Water Treatment Plant (CO8) The Coke Ovens Groundwater Collection System will aid in controlling groundwater flowing over the Coke Ovens site. Two interceptors pipe lines will be installed; one along the current alignment of Coke Ovens Brook, and the second along the west side of the site (also known as the Domtar interceptor). These two interceptor lines will flow by gravity to a central pump station that will bring the water to an on-site water treatment plant. Field tests, including a pump test and groundwater modeling, were conducted to support the project design. An on-site Water Treatment Plant will operate for approximately 25 years, and will treat groundwater coming from the Coke Ovens site. Groundwater collected by the Coke Ovens interceptor system will be transported to the plant for treatment of organic and inorganic contaminants. Discharge criteria have been established for the treated water, which will be released into Coke Ovens Brook. Landfill (CO9) Debris generated from other project elements and decontaminated at the Materials Processing Facility will be sent to an approved landfill for final disposal. Materials Processing Facility (TP2) The Materials Processing Facility is combined with the contractor s compound and will serve as the central access point to all construction activities at the site. Site control on a remediation project is a cornerstone to preventing the spread of contamination into clean areas. Operations of the Materials Processing Facility includes the ability to control the flow of traffic onto and off the site, as well as providing personnel and vehicle decontamination. The materials processing facility will also manage debris generated from other construction activities. The Material Processing Facility was constructed by local company, Joneljim Construction. The contact for the operation of the building was awarded to Mikjikj Enterprises Ltd. and Harbour Tech Services Inc joint venture. This contract will last for the duration of the cleanup and includes the decommissioning of the building once work is complete. It is expected that almost all elements will generate debris (wood timbers, slag, general waste, tires, automobile parts, etc), and construction and demolition debris. Materials received at the facility will either be crushed (concrete or slag) and sent for Solidification and Stabilization treatment, decontaminated and recycled (steel), or decontaminated and sent to an approved landfill for disposal. Mid Conference Excursion 5 5

7 IMWA 2010 Mine Water and Innovative Thinking Sydney, NS Figure 3 Tar Ponds Solidification/Stabilization, Channel Construction (TP6) All the sediments in the Tar Ponds site, including PCB material, will undergo Solidification and Stabilization treatment as a means of creating a structurally enhanced, low permeable mass that immobilizes contaminants in place. The purpose is to provide increased structural strength for capping and to decrease the mobility of contaminants. In order to carry out the Solidification and Stabilization process, surface water controls will be used to redirect surface water flows and outfalls away from the area when Solidification and Stabilization is taking place. Surface water controls will be in the form of temporary pumping stations, and in the construction of permanent channels through the Tar Ponds. The new channels will be permanent and used to bring water from Coke Ovens Brook and Wash Brook from their current entry points in the South Tar Pond to Sydney Harbour, as well as water flow from existing sewer outfalls. Steel sheetpiling will be installed at Battery Point and the Ferry Street Causeway to help control the flow of tidal waters entering the ponds from Sydney Harbour. What Is Solidification/Stabilization? Solidification & Stabilization with cement is a common method for the safe treatment, management, and reuse of contaminated waste. Developed in the 1950s, the technology is widely used today to treat industrial hazardous waste and contaminated material at brownfield sites. Solidification & Stabilization involves mixing cement and other reagents into contaminated material and works to protect the environment and our health by immobilizing hazardous contaminants within the treated material. The cement reacts chemically with water in the material being treated, creating changes in its physical and chemical properties that stabilize these hazardous constituents and prevent their escape into the environment. Soil, sediment, and sludge impacted with a variety of organic and inorganic contaminants have been treated successfully using this versatile technology. Treatment of the Sydney Tar Ponds will involve leaving the contaminants in place with cement being directly added to contaminated materials. Pump-around System (TP6 Part A) There are two brooks that flow into the Tar Ponds. Coke Ovens Brook and Wash Brook. In order to have water-controlled construction areas for Solidification and Stabilization work, both brooks need to be redirected around the north and south ponds. The Pump Around System design consists of temporary pumping stations. Each station consists of several pumps that will draw in water from constructed intake structures and move the water, through two large pipelines, to an area of the ponds where no constructions activity is underway. 6 Mid Conference Excursion 5

8 Sydney, NS Mine Water and Innovative Thinking IMWA 2010 This process will be completed in three stages. The first stage is Prince Street to Ferry Street Bridge. Stage two is Ferry Street Bridge to the narrows in the North Pond, and the third and final stage includes the narrows to the mouth of the harbor. Walls made from sheetpiling will be used to block tidal waters from Sydney Harbour from entering the ponds while work is taking place. Solidification/Stabilization/Channel (TP6B) As Solidification and Stabilization work is carried out in the North and South Ponds, a channel will be construction through the middle of the site. Once Solidification & Stabilization work is complete and the pumps are shut off, the channel will accept the flow from Wash Brook and Coke Ovens Brook. The channel will run from the South Pond at Prince Street, all the way to the mouth of Sydney Harbour. A component of cap construction is to relieve pressure caused by groundwater travelling under the solidified and stabilized mass. In order to achieve pressure relief, wells will be installed along the channel alignment and discharge into the permanent channel. Tar Ponds Cap (TP7) The Tar Ponds Cap will cover sediments treated by Solidification & Stabilization. The cap will be constructed using a combination of geotextiles, clay, and granular fill. The final elevation of the cap will be above the high tide, so that the area can be developed for future use. The surface cap will be protected from erosion by the cofferdam at Battery Point. Riprap, or other armouring, will be used as needed to manage erosion from waves, storm surges, or floods. Armoring will be provided along the waterway channels in Muggah Creek as needed to prevent erosion. It is expected that vegetation alone will likely prevent erosion over most of the area of the capped Tar Ponds. Schedule of Work The detailed design was completed in 2009 and all but one element (CO6), is either completed or in construction. The work has been planned to unfold strategically and sequentially so that, generally speaking, upstream areas are remediated first. In addition, the work has been staged in consideration of multiple contractors working at the same site, and ensuring enabling works (TP6A is an enabling contract for TP6B work) are in place in time for other work to be completed without delay. This year (2010) has been the busiest from a construction standpoint to-date, and saw the first full season of the Solidification & Stabilization work in the Tar Ponds. Next year will prove to be even more intense with respect to construction activity. By the end of 2012, only two contracts (the Solidification & Stabilization and the Tar Ponds cap) will remain to be completed. The entire project is scheduled to be completed by early spring Figure 4 Mid Conference Excursion 5 7