The meeting was dedicated to a summary of the work performed by Harding Lawson for the Port of Long Beach, to gather information on beneficial reuse projects underway in other areas. Paul Krause presented highlights from the study. A final report will be prepared and should be ready for distribution soon.

The beneficial re-use study started as an Internet search, but soon broadened to a wider scope. This is a dynamic field with lots of new developments. Although many technologies have been bench tested, little large scale testing or application of these technologies has occurred. A commonly used acronym in this field is NUAD (not suitable for unconfined aquatic disposal; public education is needed to demonstrate that this type of "contaminated" material is not the same as hazardous waste. Our contaminant levels in sediments generally appear to be much lower than those found on the east coast. The counterpoint to NUAD is SUAD (suitable for unconfined disposal).

There are some basic differences between freshwater and marine sediments. Significant chemistry changes occur when you move marine sediments to freshwater locations. Grain size is a significant factor, as certain techniques work better with fine-grained material, while others are better with coarse-grained material (generally, approximately 90% of the contaminants are found in the silt-clay fraction of the dredged material).

This technique has been tried in northern California, where contaminated material from the Port of Oakland has been used as a base layer for restoring wetlands at Hamilton Air Force Base. This type of project could be considered as volumetric fill, where the grade is restored, as opposed to construction fill, where the site would be designed to support a load (e.g., a container terminal).

A key question to be considered is who will use or buy the material to be produced by such a facility? In San Francisco, there is a desire to develop a rehandling facility, but it has been hard to find a market for the product. One of the reasons for adopting the NUAD/SUAD designations for dredged material is to improve public perception and foster re-use. So far, four possible sites have been identified for a rehandling facility. Such a confined disposal facility would be diked and possibly lined; there would be control of what type of material goes in and out. Location is the key to a good rehandling site, so that it is convenient for access, there is room to manipulate the sediment and a place for discharging water. Engineering considerations must be taken into account, such as planning dike construction for earthquake safety, developing a flow design to provide adequate retention time to allow fines to settle (e.g., a circuitous flow pattern), and accommodating the method of fill (e.g., hydraulic or mechanical dredging of sediment to be introduced to the site).

The Sonoma Baylands plans to accept 2 million cubic yards of SUAD material.

The Galbraith Golf Course plans to accept 6 million cubic yards of NUAD material to raise the elevation 15 feet at a landfill previously converted to a golf course. An NPDES permit (primarily to place metals limits on the discharge) has been issued by Regional Board 2 to decant water from the dredged material placed on the site; this decantation phase is expected to last for 2 ½ years.

The Hamilton Army Airfield originally was carved out of wetlands in Marin County. It has been permitted under the LTMS to use NUAD material to help restore wetlands elevations at the site. This would be a multi-user site, and it is anticipated that 3-4 feet of contaminated material would be placed in a lower layer, with approximately a 3-foot cap of clean material (however, design details have not been worked out).

Moss Landing Harbor lies at the base of drainage with lots of agricultural uses, resulting in high DDT levels in the sediments. A large sediment rehandling pond has been built to produce concrete from the dredged material.

The Port of Oakland proposes to create shallow water habitat within the Oakland Middle Harbor. They would use NUAD material at the bottom, with a clean cap.

Treatment options can be broken down into the following alternatives: contaminant separation (heat treatments, centrifugation), contaminant destruction (higher heating), contaminant reduction (wash with water and solvents) and contaminant stabilization (add materials, often proprietary blends). Several alternatives have been tested on the East Coast as pilot projects on a small scale; cost estimates are projected for large scale production, but have not actually been done yet.

Primarily removes lead, mercury, VOCs and some PAHs, so some contaminants remain. It is not necessary to dry the material prior to processing. The waste stream at the end of treatment (gas and left-over sediment) may be hazardous waste; the process also generates dioxins. Processing cost is $50-70 (does not include cost of dredging, handling and disposal).

The Institute of Gas Technology developed this process, but they are difficult to reach for details. It requires a higher temperature than thermal desorption, but burns off 99.99% of the contaminants. The process has been tested on 15,000 cubic yards, but should be able to handle up to 250,000 cubic yards of sediment per year. The final product is a construction-grade cement.

This is energy intensive, but gets rid of all of the organics (conversion to CO, H2 and CH4); metals may remain, but probably would be bound in the leftover material. The company testing this procedure went out of business, so there does not seem to be a future for this technique.

Pretreatment is required – the material must be dried to start with at least 58% solids. It is heated to 3000 degrees into plasma to produce glass. This destroys the organics and locks the metals into the glass. However, it is very expensive ($90-120 per cubic yard + pretreatment costs).

Good process for removing PCBs and halogenated compounds, but does not remove PAHs. Metals are not leachable from the final matrix. It is fairly expensive ($108 per cubic yard).

A proprietary process has been developed using surfactants, chelating and oxidizing agents, as well as high pressure water streams. This removes 90% of the organics and 70% of the inorganics, but leaves a waste stream for disposal. The targeted use is to treat freshwater sediments and develop the remaining waste into topsoil. The process has not been tested with marine sediments, but should work and get rid of the salts as well. Relatively inexpensive at $30-50 per cubic yard.

Sediment is mixed with fly ash, cement, lime and chemicals to form an aggregate material. The process seems more suitable to freshwater sediments, and generally is applied after contaminant removal has been accomplished, since the aggregate material may not lock up all contaminants. This process costs $30-60 per cubic yard (not including contaminant removal).

This process is being developed by the U.S. Army Corps of Engineers, primarily for use with freshwater sediments. However, tests with marine sediments look promising (need to work on getting rid of the salts). This process has not been tested on a large scale, but estimated costs are low ($20 per cubic yard).

Various processes result in end products which can be sold as construction materials (assuming that a market can be developed for them), such as bricks, cement, building blocks, glass tiles. Production costs vary, but seem to range from $20-80 per cubic yard. Large scale tests are underway and manufacturing plants are being built on the east coast. Siting issues are a concern, such as costs for leasing a site and loss of land for port use; may need a dedicated regional facility to make this work.