Engineering Disciplines


Dredging, Siltation & Material Disposal

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 with the Upper Newport Bay and its Unit III sediment basin. Services consisted of providing three construction inspectors, to oversee the contractor's dredging operation, and it 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.

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Naval Air Station, North Island, Coronado, CA.

This project included dredging at Pier Bravo and the Quaywall turning basin at North Island, Coronado. NCI performed hydrographic and underwater obstruction surveys; vibracoring; geotechnical analyses; and prepared plans, specifications, bid documents and cost estimates for maintenance dredging of Pier Bravo and the quaywall turning basin area. Services included performing dredge material quantity computations and survey mapping using CADD and Siteworks software; preparation of specifications using SPECSINTACT; and development of detailed cost estimates.


Naval Station, San Diego, CA.

This project included dredging along the main channel and berthing piers at the Naval Station in San Diego. NCI performed hydrographic and underwater obstruction surveys, as well as prepared plans, specifications, bid documents and cost estimates for maintenance dredging of six miles of channel, Piers 1,2,7,8 and 13, Chollas Creek and Poleta Creek. Services included performing dredge material quantity computations and survey mapping using CADD and Siteworks software; preparation of specifications using SPECSINTACT, and development of detailed cost estimates. Construction support services were also provided.

Sunset Harbor/Huntington Harbour, 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.
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Dredged Material Land Disposal Site, San Leandro, CA.

In a series of jobs, NCI performed several phases of a project to reconfigure the City's 112-acre dredged material disposal site. This was necessitated by a nearly full disposal site, and by permit conditions imposed by the Regional Water Quality Control Board. Work included planning to determine the optimum size and shape for handling future maintenance dredging projects; ground water quality testing; sediment sampling; engineering design and quantity computations; assistance with preparation of permits and environmental documentation; and preparation of plans, specifications, and cost estimates. Engineering services were provided through the construction phase. In preparing the long-range dredge disposal operational plan, work included computer modelling to determine the optimal size, configuration and features for operating the disposal site; evaluation of the procedures for drying and removing the material to an ultimate disposal site; determining the costs associated with dredging, preparation and operation of the disposal site and ultimate disposal; preparation of an operations and maintenance plan; and a groundwater investigation and monitoring plan.

Mandalay Bay Seawall Repair and Maintenance Bay Dredging Project, Oxnard, CA.

NCI performed a comprehensive condition survey of over 32,000 lineal feet of precast and cast-in-place concrete seawall. Design services included non-destructive and destructive testing to determine causes of deterioration; selection of repair materials and methodology; and preparation of construction drawings, specifications and cost estimates. A phased program of repair and preventative maintenance was developed. NCI's services also included full-time resident construction inspection and consultation. The City extended NCI's contract to prepare construction documents for additional phases of work. Professional underwater divers from NCI's sub-consultant Harbor Offshore, Inc. performed underwater surveys and investigations of the entire Mandalay Bay seawall foundation and slope protection areas. Over six miles of seawall were observed, logged, and compared to previous observations to assess existing conditions and identify areas of needed repair.

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.


Mandalay Canal Maintenance Dredging, Oxnard, CA.

This project involved the planning, design and permitting for the maintenance dredging of a power plant cooling water canal. Work involved hydrographic surveying, channel design, chemical analysis of sediments, preparation of permits and regulatory documents, evaluation of alternative upland dredged disposal sites, and preparation of plans and specifications for construction bidding. Noble Consultants, Inc. completed a pre- and post- dredge survey of the 11,000-foot long cooling water intake canal for the Mandalay Generating Station. The survey consisted of transverse sections across the canal at approximately 40-foot intervals along the entire length of the canal. The sections were acquired using our Trainable Acoustic Beam Sea Floor Profiler mounted on one of our survey vessels. On several occasions NCI surveyors assisted the dredge contractor in determining placement of his equipment along the winding canal. NCI surveyors conducted several interim surveys during dredging to determine compliance with the dredge plan. The data were processed and mapped using MicroStation software. Dredgeable material quantities were calculated, and electronic files of the maps were provided to the client.

Maintenance Dredging of Semeniuk Slough, Newport Beach, CA.

NCI performed a study to assess the feasibility of dredging the Semeniuk Slough. The tidal channel is an urbanized waterway that discharges directly into the Lower Santa Ana River wetlands. The scope of NCI's services included field surveying, sediment characterization, preliminary engineering, and strategic planning tasks. Technical analysis was directed to quantify the limits of dredging work necessary to restore the channel and determine the most economically feasible method to dispose of the accumulated sediment. A key component of the study was providing the City with recommendations on how best to implement and fund a project. NCI analyzed possible avenues of inter-agency coordination that might be available to the City to expedite the project and reduce the financial burden of dredging and future maintenance. NCI is currently assisting the City to move forward with a preferred dredging plan that incorporates innovative eco-system restoration measures and provisions for long-term maintenance.


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