Dredging, Siltation & Material Disposal
- Channel Shoaling, Disposal Sites, and Dredge Material Handling & Design
Listed below are many of the projects we’ve completed for our clients over the years. We’ve chosen to focus and expand on several key examples which are highlighted in blue. Clicking on those projects allows you to view in-depth what services NCI provided as well as details on the project itself.
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- Upper Newport Bay Sediment Control Dredging, Newport Beach, CA
- Sunset Harbor/Huntington Harbor, Huntington Beach, CA
- LA-3 Dredged Material Ocean Disposal Site Designation, Orange County, CA
- Naval Air Station, North Island, Coronado, CA
- Naval Station, San Diego, CA
- Dredged Material Land Disposal Site, San Leandro, CA
- Mandalay Bay Seawall Repair and Maintenance Bay Dredging Project, Oxnard, CA
- Mandalay Canal Maintenance Dredging, Oxnard, CA
- Maintenance Dredging of Semeniuk Slough, Newport Beach, CA
Upper Newport Bay Sediment Control Dredging
Newport Beach, CA
NCI supported the County of Orange’s Construction Division in overseeing the construction contractor’s dredging of approximately 1,000,000 cubic yards of material within Upper Newport Bay and its Unit III sediment basin. Services consisted of providing three construction inspectors, to oversee the contractor’s dredging operation, and in providing construction oversight as requested to support the County’s construction management staff. The contractor used both clam shell and cutter suction dredges over a 16 month period to place dredged material within dump scows (barges) which were then transported by ocean going tug boats to an EPA approved ocean disposal site approximately four miles offshore the entrance to Newport Harbor. In addition, services have been provided to the County in support of other dredge projects.
Sunset Harbor/Huntington Harbor
Huntington Beach, CA
NCI was responsible for all phases of the maintenance dredging project at Sunset Harbor/Huntington Harbour, involving 120,000 cubic yards in a 2-mile channel. Services included a project report to be used for planning, environmental documentation and permit processing; sediment sampling; sediment chemistry and bioassay laboratory analysis for ocean disposal; eelgrass survey; preparation of permit applications and an eelgrass mitigation plan; coordination with regulatory agencies; channel design; dredged material quantity computations; preparation of plans, specifications and engineer’s cost estimate; construction support services; and two years of monitoring of the eelgrass transplant in accordance with the mitigation plan. Design criteria and channel layout had to be developed since dredging had not been performed for many years. The mitigation plan involved aquatically placing acceptable dredged material to create a suitable transplant site, and then transplanting the eelgrass. After two years of monitoring, it was determined that the eelgrass transplant was a success.
LA-3 Dredged Material Ocean Disposal Site Designation
Orange County, CA
NCI reviewed EPA and Corps of Engineers guidance and regulations on the Dredge Material Ocean Disposal Site Designation (DMODSD) process and prepared an expanded Plan of Action (POA) to formulate various study tasks and associated costs including a regional Zone of Siting Feasibility (ZSF) study, oceanographic and biological baseline data collection, and EIS process for an ocean disposal site at LA-3 in Orange County.
NCI is the project manager for overseeing offshore physical and biological field surveys to establish baseline environmental conditions approved by the EPA at LA-2, a permanent ocean disposal site in Los Angeles County and the to-be-designated LA-3 of Orange County and Los Angeles County. We have managed these physical and biological field surveys which consisted of collection of bottom sediments; sediment sampling for grain size, chemistry and bentic biology; conduction of a Sediment Profile Imaging (SPI) survey; performing other trawl collections for demersal fishes and epifaunal invertebrates; performing data analysis and validation; and preparing a sampling and testing report.
The ZSF analysis was also performed, based upon the economically feasible criterion, to determine the necessity of a new permanent ocean disposal site at LA-3 as well as the protected ocean disposal volumes in a single year for Los Angeles and Orange Counties. This ZSF analysis formed the basis to propose various alternatives related to the volumetric capacity at LA-3. Subsequently, the short-term and long-term fate of dredged material disposed at LA-3 and LA-2 was modeled to assess the potential environmental impacts to the surrounding bentic communities under the EIS process. In addition, all collected field data is being integrated via the Geographic Information System (GIS) to provide continuous project management.