Isnt it safer to just cap the PCBs in place?
A cap is only a temporary fix. In an active, eroding river system it would be only a matter of time before the capping material (of sand or rock) wore away, especially in major storms and flooding. Flowing water is powerful. In addition, caps could make many important parts of the river more shallow, potentially interfering with boat traffic. As the caps eroded, they would flow downstream to fill up the shipping channels and marinas, creating more need for expensive dredging and disposal projects. Wildlife habitat would be destroyed by artificial capping materials, and much of the river would be an artificial drainage ditch, rather than a natural river. In contrast, dredging would be a permanent one-time solution, leaving a natural deeper river bottom and reducing the costs for harbor dredging downstream.
