Los Angeles Region Dredge Material Management - Aquatic Capping Pilot Project Monitoring

The multi-agency Los Angeles Basin Contaminated Sediments Task Force (CSTF) was established in 1998 to develop a long-term management plan by 2003, for dredging and disposal of contaminated sediments from coastal waters in Los Angeles County. The plan's goal is to include measures to identify environmentally preferable, practicable disposal alternatives, promote multi-use disposal facilities and beneficial reuse, and support efforts for watershed management to control contaminants at their source. To identify the most appropriate sediment disposal alternatives, four pilot and/or bench scale studies were conducted and led by one of the CSTF executive members, the Los Angeles District Army Corps of Engineers. This paper describes the monitoring program and short term monitoring results for the aquatic capping pilot study. The monitoring program was designed to collect sufficient data to evaluate the effectiveness, feasibility, and environmental impacts associated with aquatic capping and evaluate it as a potential remediation alternative for contaminated sediments in the Los Angeles Region. The monitoring program includes water quality impact assessment and dredge material loss investigations during construction and post construction monitoring (i.e., coring and bathymetry) of the capped disposal site. These efforts were completed during early 2002 and results of the monitoring in comparison to model predictions (DREDGE, STFATE, MDFATE), where available, are presented and implications for regional management of contaminated dredge material are discussed. Long-term monitoring will begin in the summer of 2002, and the design and purpose of this monitoring program will also be discussed.