• For toxicity testing, large volumes of sediment are being collected as part of the early action engineering evaluation and cost analysis near Portland Harbor.

file under: Environment, Government, Federal Government, North America, United States, Water

Cleaner, Safer Waterways

Remediation projects in Portland and Raritan protect more than the environment

For hundreds of years, the United States embraced the commercial and industrial benefits of its waterways, unaware that discharges of chemicals, untreated wastewater and stormwater, and industrial byproducts could create lasting damage to these precious resources. While today’s awareness and strict regulations generally prevent further contamination, in many cases the damage is already done. Industries and federal, state and local governments face the daunting task of cleaning contaminated sediments caused by years of poor stewardship.

There are enormous risks if these sediments release their toxins into the water column. A community can be economically affected without water assets for recreation, development or commerce. However, 90 percent of the risk is to public health, the environment and the food chain. 

Remediation Solutions
“There are enormous risks if these sediments release their toxins into the water column. A community can be economically affected without water assets for recreation, development or commerce. However, 90 percent of the risk is to public health, the environment and the food chain,” warns Jeanne Litwin, CDM Smith senior vice president.

Remediating contaminated sediments is a highly sophisticated process requiring multi-disciplined teamwork. Eric Blischke, CDM Smith environmental scientist and project manager, emphasizes the complexity of sediment remedial investigations and feasibility studies (RI/FS). “Sediment characterization requires large volumes of data, but sediments are obscured by water and constantly shift due to currents. There is so much to analyze and understand, from sediment toxicity and current sheer forces, to native aquatic species and habitats and water use and navigation.”

Traditional fixes include dredging and disposal, a difficult and time-consuming effort. “It’s one thing to dig dirt from someone’s front yard using a backhoe, it’s quite another to use a barge and dredge heavy, wet sediment from a harbor,” says Andrea Sewall, CDM Smith senior vice president. “Costs can reach hundreds of millions of dollars. Often, cities that can’t afford to develop their waterfronts and ports forego deepening their harbors.”

Contaminated Sediment Chemical Distribution and RemediationContaminant distribution analyses for Portland Harbor (each map represents a key chemical of concern) support feasibility studies and remedial action decisions.

Focus has shifted to risk reduction, which includes capping contaminants to prevent further migration and exposure to organisms, as well as monitored natural recovery (MNR), where cleaner sediments bury contaminated sediments. Advances in in-situ treatment research may lead to methods of reducing the bioavailability and toxicity of sediments. “We are collaborating with universities and other partners on more cost-effective ways to address this issue,” explains Sewall. “We are proud to help revitalize these communities and water assets. Once you restore a waterfront, you restore life and economic vitality.”

Protecting Portland Harbor
The Lower Willamette River is a critical migratory corridor for various endangered fish and serves as a cultural and recreational resource for the Portland, Oregon, USA area. However, industrial and shipping activity has contaminated river sediments with DDT, polychlorinated biphenyls, petroleum byproducts and heavy metals. Since 2004, CDM Smith has played a key role in supporting the assessment and proposed remediation of this 11-mile Superfund site.

For this high-profile project, CDM Smith is assisting the U.S. Environmental Protection Agency in evaluating capping, dredging, in-situ treatment and MNR. “We are also helping evaluate a complicated contaminant transport model that examines sediment movement and contaminant uptake by fish to predict how long before concentrations drop to protective levels,” states Pamela Philip, CDM Smith vice president. “These can be 20-year projects, but after cleanup comes the benefits to natural habitats, waterfront development and the community. For me, it is exciting to be part of something bigger than just the cleanup.”

Getting Beach Ready in Raritan Bay
CDM Smith is helping streamline an RI/FS at a 1.5-mile-long coastal site located on Raritan Bay in New Jersey, USA. In the 1960s and 1970s, slag from lead smelting was used to construct a seawall and supplement a jetty now located within a designated recreational area with swimming and fishing. Heavy metals have leached into surface water and slag particles have eroded and mixed into the sediments. Faced with an aggressive schedule to reopen these recreational areas, CDM Smith focused on early action activities, including sediment and surface water testing to determine if the beach could continue to be open during the RI/FS; development of a historic sample database to identify data gaps; and evaluation of post-storm redistribution of contaminated sediments.

Concurrent site characterization efforts involved collecting more than 1,800 samples, performing acoustic Doppler methods to support sediment transport modeling, developing detailed bathymetric and topographic profiles, and characterizing aquatic and terrestrial resources for ecological risk assessment. CDM Smith is currently conducting feasibility studies to evaluate several remedial alternatives, including reactive capping, MNR and onsite disposal in an engineered cell. “We know these projects are big issues for our clients, not only because we’re partnering with them, but because we also live in these communities,” notes Litwin.