Los Angeles Basin Contaminated Sediments Task Force

Summary of Upland Disposal and Beneficial Reuse Committee Meeting

on November 17, 1998

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Constructed Fill - Port Criteria

The Port of Los Angeles ideally prefers to accept material with less than 20% fines and that is suitable for ocean disposal (i.e., low contaminant levels) for use in constructed fill projects. Use of fine-sediments is undesirable, given the time required for compaction and potential for pockets of instability in the fill.

The Port of Long Beach is less driven by engineering constraints and willing to accept sub-optimal material. However, the port prefers material with the proper Sand Equivalence (similar to the Port of LA’s criterion) and California Bearing Ratio (a measure of structural integrity). The Port has developed criteria for accepting material with chemical contamination, based upon experience with site cleanup projects. Blending can be used to mix fine-grained sediments with better quality material, but it is a tedious and expensive process and requires extra time and space to implement. Tony Risko mentioned that it is difficult to actually blend the material, and that the standard mix for blending is 10 parts sand to 1 part fines, which requires a lot of sand to dispose of a little fine-grained material. We might need a pilot project to better define the acceptable ratio.

Assignment: We need more details about past constructed fill projects; Port of LA will provide info on Pier 300 project and Port of LB will look into Pier C project. We also need to determine the critical thickness of good material (structural integrity required) for container sites (e.g., 5 feet, 10 feet?); the Ports will look into this.

Physical Separation/Concrete Stabilization

Tony Risko summarized the Moffatt and Nichol report findings with respect to a Marina del Rey project. This report should be available by mid to late December.

Physical separation would cost approximately $30 per cubic meter to actually perform the separation, and $84 per cubic meter for full implementation; it would require a large area of beach for treatment of the material. This option has not been evaluated for Los Angeles River dredged material - we probably would need funds to conduct this study. Dredged material from the Ports probably would be too silty and would preclude this option.

Concrete stabilization would cost approximately $60 per cubic meter to perform the procedure, and $72 per cubic meter for full implementation. We would need a site for processing of the dredged material, but it does not have to be a permanent site. If the material can be marketed, this could reduce the cost. We might need a pilot project to demonstrate that the process would work in this area.

Assignment: We need to benefit from experience in other parts of the country; Michael Lyons will contact people in New York working on disposal alternatives.

Next meeting: Tuesday, December 22, 1998, 10 am to noon, LA Regional Board (Monterey Park)


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