Attendees

Catherine Tyrrell, Los Angeles Regional Water Quality Control Board
Mark Gold, Heal the Bay
Michael Lyons, LA Regional Board
Xavier Swamikannu, LA Regional Board
Dan Radulescu, LA Regional Board
Larry Smith, Port of Los Angeles
Rick Cameron, Port of Long Beach
Guangyu Wang, Santa Monica Bay Restoration Project
Jason Mubarak, MEC Analytical Systems, Inc.
Bill De Poto, Los Angeles County Department of Public Works
Menerva Daoud, LA County Dept of Public Works
Tim Piasky, LA County Dept of Public Works
Barb Klos, Woodward-Clyde
Mike Stenstrom, UCLA
Joseph Johnson, U.S. Army Corps of Engineers
Eric Sheehan, Michael Baker, Inc.
Chimin Chian, Moffatt and Nichol
Sheldon Kumicniecki, USC 

The majority of the second meeting was devoted to two presentations pertaining to stormwater studies that might aid us in our efforts to identify sources and control pollutants that result in sediment contamination and cause problems for disposal of dredged sediments.

Santa Monica Bay Consortium - Catch Basin Insert Study [handout]

Michael Stenstrom, Civil and Environmental Engineering Department, UCLA, presented the results of a study conducted in association with Woodward Clyde Consultants and Psomas & Associates. The objective of the project was to evaluate some existing and prototype catch basin devices designed to control pollutants in dry-weather and stormwater runoff. The catch basin inserts had to be designed so as not to create any additional flood risk, cost less than $500 each, not increase water depth in front of the catch basin, and require cleaning no more than twice a year. Several devices were tested in the field and in the laboratory. Field tests were conducted at four locations, representing different land uses (vehicular, light commercial, single family residential, multi-family residential). Analyses were conducted over a range of storm events (0.28 to 3.36 inches of rainfall). The results demonstrate that the contaminant load varies depending on the land use, with a modest trend towards higher concentrations associated with a first flush. Oil and grease concentrations were lower than expected. Removal of solids by inserts into the catch basin appeard to be a promising method for removal of oil and grease (perhaps up to 70 to 80%) and a portion of the sediment load in runoff (perhaps 40% of the coarser material could be captured), however the proportion of pollutants associated with this size fraction has not been determined. Additional field testing will be required, particularly to demonstrate that these devices can operate without reducing flood protection.

The Army Corps of Engineers has been working with this data set to convert it to a GIS program, which allows mapping of contaminant sources and contributions from different land uses and areas of the watershed. The COE is interested in incorporating new land use data into the model to refine it and allow mapping of smaller subunits.

Los Angeles County Department of Public Works Stormdrain Monitoring [handout]

Bill DePoto presented a summary of the status of the monitoring conducted by LACDPW over the past few years. Data is available on pollutant concentrations during dry and wet weather conditions for Ballona Creek, Los Angeles River, San Gabriel River and Dominguez Channel watersheds. A pollutant tracing model is being developed, which would track certain constituents by industry SIC codes. Although the database could be used to describe temporal trends at different locations within the stormdrain system, this type of analysis has not yet been done. LACDPW sampled 11 storm events during the winter of 1997-98, including analyses for trace metals, organics, bacteriological indicators and toxicity. Sampling has included eight different land use categories. The beta version of the tracing model should be ready by November, and verficication will be conducted after next winter's storms (1998-99 season).

Discussion

Subcommittee members expressed a desire to share data and the models, and to make sure that all of the groups are working from the same assumptions. We need to make sure that the detection limits are appropriate, particularly for the metals and organics which interest us as the normal contaminants in dredged sediments.

Next Meetings

The subcommittee agreed to hold its third meeting on Wednesday, September 16, 1998, 1:30 - 3:30 pm, Los Angeles Regional Board office (Monterey Park).The fourth meeting is scheduled for Tuesday, October 13, 1998, 1:30 - 3:30 pm, Los Angeles Regional Board office.