DST has been involved with sediment clean-ups for over 30 years. Whether a $1,000 or $10 million clean-up, DST has the experience and capability. We are intimately familiar with the bottom line: cost, regulatory compliance and rapid response.

Our professional team of environmental scientists and engineers include toxicologists, hydrogeologists, fish & wildlife biologists, civil engineers and project managers. DST has the specific expertise that is critical to sediment remediation: dredging, erosion control, hydrology, hydrogeology, geotechnics, aquatic biology, toxicology and materials.

Our practical solutions are successful because they focus on:

• applying sound engineering principals,
• effective contracting techniques and
• maximizing the benefits.

Instead of writing off a remediation as an investment with no return, DST’s focus for sediment projects is on developing solutions with tangible benefits for the stakeholders.

Planning the Remediation

The key to an effective sediment remediation program is developing measurable objectives and planning the clean-up on a site specific basis. DST’s staff work closely with our clients to identify stakeholder needs, key technical and regulatory issues, future land or facility uses, project management issues and opportunities. For a successful solution, planning requires input from a diverse team including more than just environmental engineers and scientists: geotechnical/structural engineering, surveying/mapping, geology/geophysics, data management and public information management. A thorough knowledge of the regulatory framework is crucial.

Ecological and Engineering Studies

Most sites already have some degree of information available that needs to be expanded. Because of the enormous costs associated with sample collection and analytical testing, and the huge cost implications, it is important to think through the potential outcomes in advance and to balance costs with benefits.

These investigations will focus on delineation of contaminants, their fate with time, their impacts on the environment and their associated risks. They include feasibility studies, corrective measures studies, site specific risk assessments, treatability studies and design studies.

Option Evaluation

Once a site is adequately characterized with respect to contaminants, risks, feasible treatment/disposal/confinement methods and potential opportunities for additional benefits, then specific options are developed conceptually together with costs and benefits. Selecting the preferred option can include input from regulatory departments as well as the public or other stakeholders.

Designing the Remediation

On top of the technical remediation expertise, successful designs require practical knowledge of contracting alternatives, materials handling, health and safety, regulatory requirements and project management. Designs focus on flexible details that can be

adjusted in the field to accommodate any new information that later becomes apparent. DST’s experience ensures practical designs and specifications, whether for lump sum, design-build or time & materials contracts.

Constructing the Remediation

Once a suitable contractor is on the site, DST provides construction management expertise together with quality assurance measures. While emphasizing cost control, DST’s services focus on expediting the clean-up by rapid resolution of any conflict and providing field adjustments to the design in the face of any new data that becomes apparent. This sets sediment contracting apart from conventional construction projects where conditions are typically well defined and designs are ‘cast-in-stone rather than flexible.

The Brownfield Solution

Given that ‘Brownfield’ developments are often on the harbour front, they often include a significant aquatic sediment component. DST’s practical approach to sediments on Brownfield sites typically involves a risk assessment, natural recovery enhancement and a focus on use that minimizes sediment disturbance.

Our Experience

• Thunder Bay Harbour, Ontario, Canada : Nowparc, a solution to a Great Lakes Area of Concern (AOC) on Lake Superior. The clean-up involved heavy creosote contamination from decades of wood preserving activities. DST’s concept, which included benefits for and funding by 2 government levels and 3 industrial partners, involved a combination of removal, treatment, sub-aqueas capping, containment and storm water management. Benefits included a restored wetland, new industrial property, new fish habitat, a waterfront greenbelt and new access to an abandoned harbour wharf.
• Fraser River, Burnaby, British Columbia, Canada: Developed and designed a dredging plan, sub aqueous cap, sheet pile enclosure and provided guidance to subcontractors.
• Peninsula Harbour on Lake Superior in Ontario: Clean-up of mercury contaminated sediment associated with a paper mill. DST’s solution for the AOC was to combine a dredging and confinement program with a new marina development which, while badly needed, by itself could not be economically viable.
• Jackfish Bay on Lake Superior in Ontario, Canada. This work involved developing practical options for clean-up of Lake ‘C’, a Great Lakes AOC, which contained contaminated sediment from over 5 decades of infilling from paper mill effluent. Options developed and costed included: re-channelization, lake drainage and vegetation, sub aqueous capping/confinement, stabilization, natural recovery and removal.
• Green Lake, Nakina, Ontario. Remediation of train derailment site. Developed confinement concept for locomotives embedded in a lake. Designed for protection of the downstream water quality for aquatic life and municipal use, including detailed design of fish habitat compensation and technical specifications for construction. Permitting, construction management, monitoring and reporting.
• Housatonic River, Pittsfield, Massachusetts: technical review for the engineering evaluation/cost analysis, riverbank stability, and design sheet pile containment walls.
• Kin-Buc Landfill, Edison, New Jersey: Developed restoration design alternatives (both bioengineering techniques and hard structures) for several hundred meters of a tidal riverfront that experienced erosion and scouring exposing landfill wastes.
• Lower Passaic River, New Jersey: Designed sub aqueous caps for contaminated sediments of inter-tidal areas (mud flats) of the Lower Passaic River, NJ. Provided senior review for environmental site remediation design and contracting team.
• Kalamazoo River Superfund Site, Kalamazoo, Michigan: Conducted remedial Investigation and Feasibility Study (RI/FS) reports including riverbank stability assessment and developing corrective measures, dredging feasibility assessment, and developing and evaluating remedial alternatives (e.g., bank stabilization, dredging, rechannelization, upland disposal facilities, and capping) and cost estimates.
• Lower Fox River, Green Bay, Wisconsin: Peer review and technical review on the Remedial Investigation/Feasibility Study (RI/FS) and the Proposed Plan (PRAP) prepared by Wisconsin Department of Natural Resources (WDNR). Developed a capping pilot demonstration project work plan for the Lower Fox River, Green Bay, Wisconsin. Conducted pre-design geotechnical investigation of sediments, including seepage meter measurements, sediment shear strength testing, and laboratory testing for sediment physical properties (i.e., grain size distribution, water content, and Atterberg limits). Prepared a sediment remedial action plan for sediment deposits in the Little Lake Butte Des Morts located on the Lower Fox River in the City of Neenah/Menasha. The plan included a combination of dredging with off-site disposal and capping.
• Upper Hudson River, New York: Performed peer/ technical review on the Feasibility Study (FS) and the Proposed Plan (PRAP) prepared by EPA. EPA’s plan involved the dredging of 2.65 million cubic yards of sediments from a 40-mile stretch of the Upper Hudson River.

Contacts

For more information and assistance, contact DST’s senior sediment remediation engineer, Mansur Shahid, P. Eng., P. E., at smansur@dstgroup.com.