U.S. Army Corps of Engineers, San Francisco District - Suisun Bay Channel and New York Slough, 2009 Maintenance Dredging - Sediment Sampling, Characterization, Reporting and Consulting Services
As a part of its Operations and Maintenance Dredging Program for 2009, the U.S. Army Corps of Engineers (USACE) developed a sampling and analysis plan to characterize sediments proposed for advance maintenance dredging within the Suisun Bay Federal Channel and New York Slough. The proposed dredging included currently authorized dredging of the Suisun Bay Channel and New York Slough as well as advance maintenance dredging within a portion of Bull’s Head Reach (at the western end of Suisun Bay Channel) in order to maintain the authorized depth for a longer duration. Approximately 17 miles long and 300 feet wide, Suisun Bay Federal Channel and New York Slough are vital deep-draft shipping channels extending from the Carquinez Strait at Martinez to Antioch and serve commercial vessels en route to ports from Concord to Sacramento. The USACE contracted with ADH to carry out the sampling and analysis plan and evaluate the sediments for multiple disposal/reuse options.
Based upon the USACE’s Suisun Bay Channel and New York Slough 2009 Maintenance Dredging Sampling and Analysis Plan (SAP), ADH developed and managed all technical aspects of this contract. In association with our vessel and vibracoring subcontractors – TEG Oceanographic Services and Monterey Canyon Research Vessels, Inc. - ADH staff, performed all sediment coring and site water sampling from four channel composite areas.
Technical challenges to vibracore sediment collection were minimized by scheduling sample collection to coincide with favorable wind, sea-state and slack-tide conditions, and during periods of low vessel traffic. Surficial sediment composite samples from the in-Bay disposal areas were efficiently collected with a stainless-steel pipe dredge sampler.
Composite samples were analyzed for grain size (for confirmation of Tier I assumptions), total solids, total organic carbon (TOC), and dissolved metals by a modified Waste Extraction Test (mWET). All physical and chemical analytical testing was performed by Columbia Analytical Services (CAS) in accordance with the project SAP, the Inland Testing Manual, and the Upland Testing Manual. All analytical results were evaluated by ADH to determine the channel sediment’s suitability for multiple disposal/placement options including in-Bay disposal and upland placement Sherman Island. Sediment chemistry and toxicity results were evaluated in relation to relevant water quality criteria, including the California Toxics Rule, the San Francisco Bay Basin Water Quality Control Plan (Basin Plan), Waste Discharge Requirements (WDRs) criteria for various upland reuse/disposal sites - including Sherman Island (referenced from several WDRs, including that for the Stockton Deep Water Ship Channel) - and the California Drinking Water Standards’ Primary Maximum Contaminant Levels. Draft and final sediment evaluation reports were prepared by ADH for the USACE and followed guidelines provided in the SAP and Public Notice 99-4: Sampling and Analysis Plan (Quality Assurance Project Plan) Guidance for Dredging Projects within the San Francisco District.
The project was overseen by the USACE, and the final report incorporated comments from the USACE and agencies from the Dredged Material Management Office, including the San Francisco Bay RWQCB, the Bay Conservation and Development Commission, and USEPA Region 9.