Sediment Remediation

Sediment contamination has the potential to adversely and severely effect the environment and the health of all that rely upon clean waterways for daily existence.

"A large variety of contaminants including PCBs, dioxin, pesticides, heavy metals, hydrocarbons and other pollutants from industrial, agricultural, urban, and maritime activities are associated with sediment particulates, including bottom sediments." ("Contaminated Sediments," EnviroTools.com Factsheet.)

When Absorption Technologies, a SDB, DBE 8(a) certified company (NAICS 562910), takes on a sediment remediation project we carefully chooses the most appropriate and effective remedy.

While there are many similarities from site to site, each project has its own unique challenges. We throughly analyze each situation starting with understanding our client's requirements.

Our process includes understanding the site and sediment, implementing source controls, describing available options and providing for monitoring and management. When laying out the options, we advise clients of the risks and rewards for each approach. "In the remediation context, risk assessments for sediment projects involve complex relationships for both exposure and effects." We consider

Hydrodynamics, adjacent resources and infrastructure, water depths, and other factors
Contaminated volumes or areas to be addressed, the regulatory framework under which the project will be evaluated, and other factors
The contaminants of concern,
Contaminant concentrations
Sediments,
The effects of debris on our ability to dredge, cap, contain or treat the sediments.

We strive to balance environmental protection and economic efficiency. Our experience has shown that, for large or complex sites, combinations of options are often the most efficient remedies.

Absorption Technologies, a SDB DBE 8(a) certified company (NAICS 562910), is capable of executing the breadth of sediment remediation options encompassing non-removal methods like monitored natural recovery and in-situ capping; or removal methods such as dredging with containment, and dredging with sediment treatment. Our standard approaches include:

Monitored Natural Recovery (MNR): Monitored Natural Recovery is a remedial option which relies on natural processes to contain or reduce the bioavailability or toxicity of sediments left in place. Processes important to MNR include burial and in place dilution following deposition of clean sediment and biodegradation or abiotic transformation processes which convert the contaminants to less toxic forms.
In situ Capping: In-situ capping (ISC) is an active remediation option in which a layer of clean isolating material (usually a clean sediment or soil) is placed to contain and stabilize the contaminated sediment in place. A variety of capping materials and cap placement techniques are available, and monitoring data collected for a number of projects has indicated capping can be an effective remedy.
Environmental Dredging: Removal, including both dredging and dry excavation following dewatering or stream diversion, is the most common approach for sediment remediation in the U.S.
Containment in CDF's, CAD's and landfills: Containment refers to placement of dredged material in a disposal site with associated design features to hold the contaminants within the site. Confined disposal facilities (CDFs) and Contained Aquatic Disposal (CAD) sites are commonly used for contaminated sediments from navigation dredging and have also been used for remediation projects. But, by far, the most common containment option in the U.S. for contaminated sediments dredged for purposes of remediation has been disposal in licensed landfills.
Sediment treatment: Sediment treatment refers to the use of physical, chemical, or biological processes to destroy or degrade contaminants or immobilize the contaminants within the sediment.

Location: Hydepark, MA. Project: We performed a PCB cleanup of a 1600 linear foot segment of the Motherbrook River. Our first task was diverting the water.

Diversion was accomplished by damming the river on both sides, and pumping the water around the contaminated aread.

We excavated the contaminants and transported the material to a regulated facility. The river bed was backfilled with clean soil and the river was returned to its natural state.