U.S. Army Corps of Engineers, San Francisco District - Humboldt Harbor Channel, 2010 Maintenance Dredging and MOD 1 - Sediment Sampling, Characterization, Reporting and Consulting Services

Deployment of vibracore sediment sampler for collection of core samples up to 20
Prime Contractor: 
Location: 
Period of Performance: 
March, 2010 to April, 2010
Project Description: 

As a part of its Operations and Maintenance Dredging Program for 2010, the U.S. Army Corps of Engineers (USACE) developed a sampling and analysis plan to characterize sediments proposed for dredging within the Humboldt Harbor Channel in Humboldt Bay. Although the proposed 2010 dredging was for only one of six reaches within the Humboldt Harbor Channel, sediment characterization was planned for all channel reaches. Approximately 14 miles long and 39 square miles in size, Humboldt Bay is the second largest coastal bay/estuary in California and is the only major shipping port and harbor of refuge for large vessels between San Francisco and Coos Bay, Oregon, a distance of 440 miles. The USACE contracted with ADH to carry out the sampling and analysis plan and evaluate the sediments for multiple disposal/reuse options.

Scope of Services: 

 

Prior to work initiation, ADH’s review of the USACE’s Humboldt Harbor Channel 2010 Maintenance Dredging Sampling and Analysis Plan (SAP) led to a revision of the SAP, as documented in the New Humboldt Harbor Channel Sampling Scheme. This resulted in a significant reduction in the scope of the sampling required and reduced costs for the USACE. Based on these documents, ADH developed and managed all technical aspects of this contract. In association with our vessel and vibracoring subcontractor - TEG Oceanographic Services - ADH staff performed all sediment vibracoring and site water sampling at six composite areas as well as sediment and water grab sampling at the Humboldt Open Ocean Dredged Site (HOODS) reference area. Composite sediment samples were analyzed for either confirmatory physical parameters (grain size, total solids, total organic carbon) or a suite of physical and chemical constituents. All physical and chemical analytical testing was performed by Columbia Analytical Services (CAS). Analytical methods and procedures followed those specified in the SAP, the Inland Testing Manual, and the Ocean Testing Manual.

Sediment analytical data were evaluated by ADH in relation to criteria relevant to ocean disposal and beach nourishment options, specifically the HOODS reference site database. 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. After the initial sediment characterization and evaluation report was completed, the scope of work was modified in order to further evaluate sediment grain size within one of the channel reaches. Additional testing was performed on certain samples and a separate report was prepared, providing a second evaluation in regard to disposal options that was based on the new analytical results.

The project was overseen by the USACE, and the final report incorporated comments from the USACE, North Coast Regional Water Quality Control Board (NCRWQCB), USEPA Region 9, and the California Coastal Commission.