In situ solidification/stabilization (ISS) has been used at many manufactured gas plant (MGP), brownfield, and Superfund sites. ISS mixes cementitious reagents with contaminated soils reducing the bioavailability and leachability of contaminants. ISS can also be optimized to control certain ll soil characteristics, such as compressive soil strength and reduce hydraulic conductivity. Various reagents are used to promote ISS including Portland cement, blast furnace slag, lime kiln dust, etc.
ISS is often applied at highly contaminated petroleum hydrocarbon sites decreasing the leachability of BTEX, naphthalene (NAP) and other organic contaminant in soil. Cementation reactions also decrease hydraulic conductivity (K), which diverts groundwater flow away from the solidified/stabilized soil. ISS treatment also increases unconfined compressive strength (UCS), often critical for redevelopment.
However, high concentrations of organic contaminant can interfere with cementation reactions requiring excessive application of amendments increasing both amendment and disposal costs of the displaced soil. This ISS limitation can be minimized by utilizing a NOVEL combined remedy approach like In Situ Chemical Oxidation to degrade some of the organic contaminants present.
ISCO combined with ISS has been found to be able to achieve the same or better leachability and compressive soil strength values with less overall reagent addition and displaced soils. Combining one or more remediation technology generates synergies by exploiting the strengths and minimizing the weak- nesses inherent in individual technologies. When successful, combining remedies enhances performance and/or reduces costs compared to each technology used alone.
Presenter:
Jean Paré, P. Eng., Vice-President – Sales & Marketing, Chemco inc.
Randle Reef (Hamilton Harbour) Abstract
Randle Reef (Hamilton Harbour Area of Concern (AOC), Lake Ontario is the largest Polycyclic Aromatic Hydrocarbon (PAH) contaminated sediment site (695,000 m3) on the Canadian side of the Great Lakes and in all of Canada. The $138.9 M remediation project involves the completion of three stages of construction to manage PAH and heavy metal contaminated sediments. The project is being led by Environment and Climate Change Canada and is funded by Canada, Ontario, the City of Hamilton, the Hamilton Oshawa Port Authority (HOPA), Stelco, the City of Burlington and the Regional Municipality of Halton. Stage 1 involves constructing a 6.2 hectare engineered containment facility (ECF) around the most severely contaminated sediments. Stage 2 is the hydraulic dredging of surrounding contaminated sediments and placement of the dredged sediment within the ECF. Stage 3 involves capping of the ECF and consolidation of the dredged sediment contained within. The completion of all three stages of the project is scheduled to take eight years. Stage 1 construction of the ECF was successfully completed in 2018 and Stage 2 environmental dredging is scheduled for completion in October 2021. Stage 3 ECF capping is scheduled to go out for tender later this year with project completion scheduled for October 2023. Upon completion the ECF will be developed, monitored and maintained by HOPA as a marine terminal. Cleaning up Randle Reef is a critical step towards restoring Hamilton Harbour and removing it from the list of AOCs that are described in the Canada-U.S. Great Lakes Water Quality Agreement.
Presenter:
Roger Santiago, Head of the Sediment Remediation Unit, Environment and Climate Change Canada