Sediment Capping Technologies

Solutions for in-situ capping of contaminated sediments

CETCO provides a range of solutions for remediation of contaminated sediments. Contaminants may be treated in-situ, reducing risks and project costs. Depending on the site conditions traditional sand caps may prove unfeasible, or result in an excessively thick design. Sediment capping technologies provided by CETCO address concerns about navigation, placement, biointrusion and flow patterns. Active cap designs incorporate active or adsorptive media to capture or treat the contaminants and result in a reduced thickness of the cap design.



Request Assistance

Addressing challenging erosion conditions

In-situ cap must be designed to ensure protection from erosion for waves, currents, storms or ice. CETCO offers the Triton Marine Mattress system for maximum protection from erosion conditions. This system can be combined with either active capping or traditional capping materials.

Benefits of utilizing CETCO technologies

  • Reactive capping media available in either bulk or as a reactive mat allowing for wider variety of application methods
  • Combinations of reactive core materials allow for a wide range of treatable contaminants Adsorptive capacity reduces required cap thickness, thus increasing navigable depth when compared to traditional methods
  • Composite layer stabilizes sediments, minimizing re-suspension and reducing downstream impact
  • Consistent sheet size allows for highly accurate placement and maximum coverage
  • Product properties insure verifiable coverage of sediments due to fully contained, defined mass per area of reactive material
  • Reduces multi-step dredging process into fast, easily adjustable, consistent installation
  • Reductions in volume of capping material needed combined with speed of installation offer significant economic benefit


REACTIVE CORE MAT is a patented permeable composite mat consisting of reactive material(s) encapsulated in a non-woven core matrix bound between two geotextiles. The upper geotextile is a needle-punched, non-woven fabric that is heat-laminated to a matrix of nonwoven fibers needle-punched into a woven geotextile. Through its innovative processing, RCM can combine two active materials, if required.


REACTIVE CORE MAT APATITE is a permeable composite of geotextiles and a mineral that adsorbs and sequesters certain metals from water.


The TRITON MARINE MATTRESS System is used in conjunction with REACTIVE CORE MAT, a mat designed to sequester and treat contaminants within the sediment. The mattress is constructed of an advanced geogrid designed to be integrated with available fill and is used to simplify construction and provide protection in highly erosive conditions.


BENTOBLOCK® is natural sodium bentonite screened to 3/8 inch (0.95 cm) to 3/4 inch (1.90 cm) in size. BENTOBLOCK is certified to NSF/ANSI Standard 60, Drinking Water Treatment Chemicals - Health Effects.

BROS Superfund Site

Logan Township, New Jersey

Historical operations at the BROS Super-fund Site included waste oil storage, processing and disposal. The wastes, which contain heavy metals, PCBs, and other organic compounds, have seeped into the soil and contaminate surface waters and ground water supplying private drinking wells. The Site was placed on the Superfund National Priorities List in 1983. Remediation of the BROS Superfund Site was complex and required management of many interconnected issues.

Download Full Case Study

Collins Cove Sediment Cap

Beverly, Massachusetts, U.S.A

The Triton® Marine Mattresses by Tensar® was installed in a former manufactured gas plant (MGP) site to protect the underlying Reactive Core Mat®. This site is now protected against severe erosion caused by weather and waves.

Download Full Case Study

Grand Calumet River

East Chicago, Indiana, U.S.A

In 2009, clean up began on a one-mile stretch of the West Branch of the Grand Calumet River. This project involved the mechanical dredging and removal of 82,000 cubic yards of sediments and soils impacted with PAH, PCB, and various heavy metals. The estimated $33 million project was funded under the Great Lakes Legacy Act (GLLA), with the GLLA contributing to 65% of the overall project cost.

Download Full Case Study

Harbor Point Cap

Utica, New York, U.S.A

After dredging of a Utica, NY harbor was completed in 2010, investigations revealed residual concentrations of the primary constituents of concern, which included NAPL and PAHs. It was decided that a reactive cap solution should be incorporated into the remedial design to mitigate exposure risks.

Download Full Case Study

Island End Sediment Cap

Boston, Massachusetts, U.S.A

The sediment cap project is situated on a former manufactured gas plant (MGP) site located adjacent to the Boston Harbor. Previous remedial work included dredge and disposal in CAD cell and cap. Persistent sheen resulting from gas ebullition was apparent.

Download Full Case Study

Koppers Wood Treatment Facility

Guthrie, KY

This is a case study of an active wood-treatment plant that has operated in southwestern Kentucky since 1913. Historically, released DNAPL had migrated along the fill-soil interface and had impacted the drainage ditch, soil and seep locations.

Download Full Case Study

McCormick and Baxter Superfund

Portland, Oregon, U.S.A

The former McCormick and Baxter Creosoting Company is located in Portland, Oregon on the Willamette River. This Superfund Site encompasses approximately 41 acres of land and an additional 23 acres of contaminated sediment.

Download Full Case Study

Meco Drive

New Castle, Delaware, U.S.A

The U.S. Army Corps of Engineers (USACE) and The Delaware Department of Natural Resources and Environmental Control (DNREC) solicited proposals for the remediation of a storm water ditch that was contaminated with heavy oils containing PCBs and PAHs. The ditch had seeps which were contributing to the contamination in the Little Mill Creek (the outfall for the ditch).

Download Full Case Study

Pine Street Canal

Burlington, Vermont, U.S.A.

A manufactured gas plant operated at the Pine Street Canal site from 1895 to 1966. The plant disposed of wastes from the gasification process, including coal tars, which migrated to a canal on the site. In addition, the sites’ history includes activities at a tie-treating facility resulting in DNAPL discharching to the subsurface. As part of many remedial efforts at the site, a sand cap was constructed in 2002 to cover contaminated sediments and restore nearby wetlands.

Download Full Case Study

Railroad Tie Treatment Facility

Escanaba, MI

The groundwater at a former creosote wood treating site was contaminated by non-aqueous phase liquid (NAPL). The contaminated groundwater was a threat to the nearby fresh water bay when NAPL and soluble organics were showing on the surface of the bay.

Download Full Case Study

Stryker Bay

Duluth, Minnesota, U.S.A

Stryker Bay was heavily polluted from the late 1800s through 1962. The harbor area was ringed with tar and coke plants, heavy industry and slaughterhouses that all discharged industrial waste into the water. The sediment in the bay, slips and part of the river is contaminated with mercury, polyaromatic hydrocarbons, lead and other toxins as well as a NAPL seep on the east side.

Download Full Case Study

Zidell Barge Company

Portland, Oregon, U.S.A

Cleanup is required for land which was contaminated with a variety of chemicals as a result of ship construction, ship breaking, and barge construction at a site where heavy industrial use dates back to the early 1900’s. In addition to the site’s former industrial uses, several private and municipal storm sewer outfalls discharge directly to the Willamette river.

Download Full Case Study