Dredging '02: Key Technologies for Global Prosperity

This paper presents planning studies for dredged material placement in Florida, describing and reflecting upon the coordination of the planning efforts. The paper contrasts the coordination of two large-scale efforts for Tampa Bay, Florida, with that of a small-scale effort for Hernando Beach, Florida. The paper presents models for coordination of such planning efforts.

Considering the applicability of geo-tube method for the swamp restoration, three aspects, 1) filtration effect, 2) durability and 3) vegetation of the geo-tube, were investigated through experiments. The geo-tube method appeared to have an effective function of filtration, holding fine soil particles within a geo-tube. The strength of geotextile significantly decreased when exposed outside, becoming 10 to 20% of the initial value after 16 months. Even when the geo-tube was covered by plants, the strength decreased by about 30% in 16 months. Plants could grow through geotextiles, but roots and stems made holes in geotextile.

This paper focuses on the design and construction of two recent projects in Bremerton, Washington and Ketchikan, Alaska. In the Bremerton project, 57,000 cubic yards of fine-grained sediments were used to improve near-shore habitat and 35,000 cy were placed in an underwater stockpile for use as cap material. Approximately 400,000 cy were placed in a confined aquatic disposal site and were capped by 22,000 tons of sand. In the Ketchikan project, extremely soft, organic sediment was capped with 30,000 tons of sand over an area of approximately 26 acres.

This paper will discuss the advancements made in the small dredging field ( four inch to twelve inch pump discharge diameters ) over the past 30 years in horizontal auger, cutterhead, swinging ladder, lagoon pumpers and specialty dredges.

The problems associated with dredging and disposal in the New York and New Jersey Harbor area over the past 10 years have triggered sedimentation avoidance as being one of many possible tools in an ever-growing arsenal of dredged material management technologies. With overall project costs associated with the permitting, dredging, transportation, and disposal of dredged material reaching a typical value of $50 per cubic yard in the harbor, it is apparent to many that technologies which can reduce sedimentation within a berth are worthy to pursue. This paper discusses the results of a two year program which examined the effectiveness of a pneumatic control system to reduce or eliminate accretion of sediments within an active barge berth. Sold under the trade name Air Guard, this system was installed at a pier berth on the Kill Van Kull in Bayonne, New Jersey. Owned and operated by IMTT-Bayonne, the pier berth was dredged in early 1998, and the system was subsequently installed in 1999. The objective of the study was to evaluate environmental and hydrographic data between adjacent berths and to develop a cost-benefit ratio for users to apply when considering this technology for other sites. Over the course of the study period, hydrographic surveys, water quality studies, and fish surveys were performed to evaluate the effectiveness and potential environmental impacts of the system. Results indicate that Air Guard can be used to reduce dredging requirements in pier berth areas in an economically and environmentally sound manner.

The Houston Ship Channel (HSC) and the smaller channels intersecting it require maintenance dredging on a routine basis. Historically, dredging there has been performed using cutterhead dredges with dredged materials placed in Confined Disposal Facilities (CDF) for retention and management. In recent years, innovative sediment management tools have become commercially available to manage sediment shoals at projects where site conditions are suitable for their use. One of these tools, the SILT Wing Excavator, a patented device from the United Kingdom has been operating in the United States at Greens Bayou on the Houston Ship Channel for redistributing soft materials within the channel. There are distinct advantages to using these water jetting devices: there is no dredged material to be placed in a CDF for costly management; the systems are capable of operating in relatively busy channels without unduly interrupting waterborne traffic; and costs may be lower than traditional dredging operations. Disadvantages to the use of these sediment management tools include: the maintenance materials must eventually be removed from the system; bottom materials to be removed by these dredges and site conditions of the projects must be suitable; and there is a question of impacts on water quality associated with their use. The Corps of Engineers, under its mission to identify and demonstrate innovations in dredging technologies, observed the SILT Wing Excavator in operation and made monitored the resuspension of sediments into the water column. This paper describes the technology, presents examples of the results of the demonstration project at Greens Bayou, and outlines plans for future observations of this and similar sediment management devices being considered for demonstration by the Corps of Engineers.

Cement using dredged material as a replacement source of iron and aluminum is currently being manufactured in a laboratory muffle furnace under conditions mimicking those of a typical cement plant. A mass balance of heavy metals will be presented, along with leaching tests on the cement and concrete product. Studies characterizing the solid phase speciation of dredged materials and the mineral phases incorporating heavy metals in the cement material are underway. This characterization process is necessary to ensure the protection of environmental and community health as well as the health of the workers at the cement manufacturing plant. Micro-structural and environmental assessments of the feasibility of manufacturing cement with contaminated dredged material will be considered from both a practical and economical standpoint.

In response to severe damages that occurred due to the strong Kobe earthquake of January 1995 in Japan with a magnitude of 7.2 in Richter scale, a strategy was adopted to enhance the earthquake resistance of the infrastructures in the coastal areas by stabilizing the waterfront structures using lightweight slurry fill. The aims were to reduce the lateral pressure behind the damaged retaining structures and to reduce the risk of liquefaction by using a nonliquefiable fill material. As part of these attempts, this paper presents the case study of reconstruction of a damaged caisson-type seawall that moved 0.8 to 3.8 m in the horizontal direction and settled 1.1 to 2.5 m due to the Kobe earthquake. The backfill was comprised of dredged material obtained from seabed, mixed with air foam and portland cement. The properties of this lightweight fill are presented up to 10 months after the construction. Relationships are developed to correlate various laboratory and field tests. The restoration strategy adopted for this project represents an effective use of marine resources for construction purposes in the coastal areas.

Between 1993 and 1999 over 19 million m³ of sand were placed on exposed, high-energy beaches along the northern coast of New Jersey (USA) as an erosion control measure. As part of a multi-faceted biological monitoring program, potential impacts of this large-scale beach nourishment project on benthic infauna and fishes in the intertidal surf zone, nearshore habitat, and offshore borrow areas were examined. Food habits analysis was conducted on northern kingfish (Menticirrhus saxatilis), Atlantic silversides (Menidia menidia) and rough silversides (Membras martinica) collected in the surf zone, and winter flounder (Pleuronectes americanus) and summer flounder (Paralichthys dentatus) collected at the borrow areas to assess impacts to trophic linkages in the two project areas. Monitoring of benthos and fishery resources was conducted for three years before nourishment, during placement, and up to two years afterwards. The basic sampling design included multiple reference sites and several monitoring components integrated into a cohesive program. In general, impacts on the benthos were found to be short-term (2–6 months) and spatially limited. Stomach contents analyses revealed that the fishes examined have a diverse diet that includes non-benthic prey resources. Prey biomass in kingfish and silversides was usually greater in fishes caught at beach nourishment stations rather than at reference stations when significant differences were detected. Food habits of winter flounder, a benthic omnivore, and summer flounder, an epibenthic feeder, did not change relative to the dredging activities. Winter flounder fed primarily on anemones, which were not common at any of the borrow areas. Results of the present study call into question the need for extensive monitoring of projects where a close match exists between fill and receiving beach sediments. Further studies are definitely needed, however, where fill and receiving beach sediments aredissimilar.

The U.S. Army Corps of Engineers, New Orleans District (NOD) annually removes approximately 90 million cubic yards of dredged material from 10 Federal navigational channels throughout coastal Louisiana. Approximately 27 million cubic yards (25–35%) of this material is used for coastal wetland restoration projects. A total of about 16,800 acres of a variety of land habitats have been constructed by the NOD using dredged material since 1975. Approximately 10,000 of these acres are wetlands. As a result of the magnitude of coastal wetland loss in Louisiana, the NOD has come under increased pressure to use all of the dredged material for wetland creation/restoration. In addition to the Corps of Engineers' policy relative to a "Federal Standard", logistics; physical and chemical characteristics of the dredged material; channel dynamics and concern for safety of navigation; and land use conflicts limit the amount of restoration that can be accomplished with dredged material from Federal navigational channels.

The report contains a series of 18 recommendations, a section on different beneficial use applications with examples throughout the Great Lakes basin, a section on innovative technologies for treating contaminated dredged material, and profiles of the regulatory framework for beneficial use of dredged material for each of the Great Lakes states. The GLDT has selected five of the recommendations for highest priority action and has developed an implementation strategy for these five items. Actions are underway to pursue the strategy. The Great Lakes Commission has formally adopted two resolutions calling for beneficial use of dredged material as a priority management option, increased federal research and funding, and expanded Corps authorities for beneficial use.

This paper presents a summary of the history, process of the development, and design of the Houston-Galveston Navigation Channels widening and deepening project. The Houston-Galveston Navigation Channels Project will widen and deepen the Houston Ship Channel from 40 feet x 400 feet to 45 feet x 530 feet over a 53.5 mile distance from the Gulf of Mexico to the confluence of Buffalo and Boggy Bayous. Over the 50-year project life of initial construction and maintenance of the channel, some 3,889 acres of marsh, upland, and colonial water bird habitat will be created under the Beneficial Uses Plan. The Beneficial Uses Plan will have a net positive environmental benefit on the Galveston Bay eco-system and is not a mitigation plan, but recognizes and treats dredged material as a resource. The project demonstrates that improvements to commerce and navigation are compatible with the need for environmental restoration. The process for the development of the Beneficial Uses Plan is unique in that a partnership of resource agencies along with the federal and local sponsors defined the final plan. The process has proved to be very successful and can be adapted to other navigation projects.

Breton Island is the southernmost island in the Chandeleur Island barrier system located off the southeastern Louisiana coast. It is subject to severe damage from tropical storms and hurricanes. Prior to Hurricane Georges in 1998, Breton Island consisted of about 180 acres. After Hurricane Georges, the island consisted of about 125 acres with the mid-island area having been eroded away. During a 1999 maintenance dredging event of the nearby Mississippi River-Gulf Outlet (MRGO) navigational channel, the U.S. Army Corps of Engineers, New Orleans District (NOD) placed shoal material removed from the MRGO directly on the northern portion of Breton Island and at an adjacent sacrificial feeder berm site to repair storm- and hurricane-related damage. Three breaches in the northern portion of the island were plugged by direct placement of dredged material. A fourth breach was filled by material transported from the feeder berm site by wave action. The restoration project was authorized and funded pursuant to Section 204 of the Water Resources and Development Act of 1992 with the Louisiana Department of Natural Resources acting as the non-Federal cost sharing partner.

Over the past few years the University of Rhode Island (URI), Marine Geomechanics Laboratory and the Maguire Group Inc., (MGI) have gathered significant data and conducted tests relative to beneficial use of dredge materials from the Quonset Point/Davisville port in Rhode Island. The objective was to determine the most feasible beneficial use options for the various sediment types that will be encountered. A program is currently underway to carry the research forward to a prototype-testing program. The sources of data consist of earlier subsurface investigations conducted by MGI, and a joint URI/MGI research project, sponsored by the URI Transportation Center, conducted in 2000 and 2001. In the recent research project, cores were obtained using a Large-diameter Gravity Corer and a vibracorer. Sediments were characterized using a Multi-Sensor Core Logger for bulk density profiles and then classified in a laboratory testing program that included Atterberg Limits, grain-size analyses, and organic and chemical testing. Based on sediment types and classifications, bench scale tests were conducted to determine possible beneficial use alternatives. These alternatives included: direct use for landfill and construction applications, brownfield encapsulation with the low permeability sediments, cement enhancement, lime stabilization, and blending with coarser materials such as crushed demolition debris for use as common borrow. Bench-scale testing included compaction tests, strength tests with the additives, permeability experiments and chemical analyses.

Federal agencies are being required to do more with less. The U.S. Army Corps of Engineers must maintain existing federal inlet and entrance channels and respond to authorizations for channel deepening and new channels with a budget that does not increase commensurately. The answer to serving the Nation's needs in an era of declining resources is to advance understanding of inlet processes and incorporate this knowledge in operation and maintenance practices of navigation projects. The Coastal Inlets Research Program was established 5 years ago with the mission of advancing knowledge and developing predictive technology to reduce the cost of dredging, promote navigation channel reliability, and understand the sediment-sharing interactions between inlets and adjacent beaches. This paper describes this productive research program and introduces selected results.

The shifting channels at the entrance to Willapa Bay make bar navigation unreliable, and the local port is having difficulty attracting commercial users. The Seattle District requested the U.S.Army Engineer Research and Development Center (ERDC) conduct a study to determine the technical feasibility of maintaining a reliable channel (28-ft depth including advance dredging and over-dredging allowance) over the entrance bar and into Willapa Bay. The strong wave and tidal current environment require innovative approaches to sustain a reliable channel via dredging and adjusting to relatively long-term cycles of channel morphology. This paper reviews the channel engineering and morphological analysis required to determine viable alternatives that might provide a reliable channel.

A numerical model of circulation and sediment transport was applied to calculate the current, water level, and change in bottom elevation over time. This predictive capability allows for assessment of channel performance for existing and proposed configurations. The circulation model, called M2D, is a two-dimensional, depth-integrated, finite-difference model that calculates water level and two horizontal components of the current. Robust wetting and drying algorithms are contained within M2D and functioned well on the Willapa Bay tidal flats. Comparison of measured and calculated water level and velocity at three measurement stations distributed along the Bay Center channel showed good agreement, which is essential for accurate calculation of sediment transport. Calculated bottom-elevation change agreed well with measurements in areas where the bathymetry is well known, such as shoaling in the Bay Center Entrance Channel. In surrounding areas where bathymetric data were unavailable, calculated changes in bottom elevation were less accurate.

This paper describes a monitoring program to obtain high resolution and continuous measurements of estuarine physical processes and bathymetry in and near the Bay Center Entrance Channel in Willapa Bay, Washington. The field data provide valuable insights for identification of relevant processes and mechanisms controlling sediment transport in the channel and for establishing their relative importance in causing channel shoaling of a dredged navigation channel. The goal is to develop and improve numerical models used to predict estuarine sediment transport and morphological change at a range of scales. Planned maintenance dredging of the Bay Center Entrance Channel provided the opportunity to monitor bathymetry, hydrodynamics and suspended sediments in the channel to document pre- and post-dredging morphology and sediment transport processes. Dredging removed 178,00 cu yd from the channel in a 40-day period. Channel depth was excavated from 0 ft to 15 ft at its most constricted location. Process measurements were made at three stations, two in the Bay Center Entrance Channel (East and Middle Stations) and one in the Nahcotta Channel near the confluence with Bay Center Entrance Channel (West Station). The measurements during the period preceding and immediately following dredging span the season in which the channel has been observed to change location seasonally over a period of two decades. Measurements are interpreted with morphology changes to specify processes that are responsible for the observed pattern of channel changes. Varying asymmetry in the tidal flow induces a net transport toward the channel mouth that combined with local deceleration of the current results in deposition in the channel reach that has historically shoaled most quickly.

This paper presents results of a hydrodynamic and geomorphologic study of the river and tidal flow at the intersection of the Gulf Intracoastal Waterway (GIWW) and San Bernard River, Texas, to develop alternatives for reducing the current in the GIWW. The hydrodynamic modeling indicates that the presently elongated and constricted river mouth has greatly reduced the flow as compared to a channel running straight to the Gulf of Mexico, the historic orientation. Relocation of the river mouth to its original position can decrease flow along the GIWW. The recommended alternative is to restore the migrating river mouth to its historic position.

From the initial Superfund listing in 1983 through completion of final dredging and capping efforts expected to occur by 2005 — this paper surveys the author's perspective of two decades of cleanup efforts in Commencement Bay. When construction, is completed almost three million cubic yards of dredged material will be addressed, directly aiding redevelopment. Capping and monitored natural recovery will also be employed to improve environmental conditions. Costs are projected to exceed two hundred million dollars for source control actions and sediment cleanup. Key motivators in the process are offered that are making the cleanup a success for a wide range of stakeholders. Obstacles and opportunities in the cleanup process are discussed along with solutions that keep the process moving. A reflection on cleanup efforts is provided in light of the U.S. Environmental Protection Agency's (EPA) emerging national policy for dealing with contaminated sediments. Also, a hindsight view of the cleanup effort is offered. Did the cleanup really need to take twenty years?

The Port of Tacoma and the City of Tacoma are both vitally interested in moving forward on dredging and clean up of Commencement Bay. At the same time, both the Environmental Protection Agency and the US Army Corps of Engineers have responsibility for assuring that any activities taking place comply with the applicable laws and regulation governing sediment analyses and clean-up. Several of the waterways within Commencement Bay have been cleaned up. Over 150 acres of contaminated sediment remain, and as much as 1.8 million cubic yards of sediment may be dredged. Although Commencement Bay/Nearshore Tideflats is listed as an NPL site, some portions are outside areas of concern. In addition, within the areas of concern, not all sediment proposed for removal is contaminated. Some may be suitable for in-water placement. CERCLA laws and regulations and Clean Water Act laws and regulations were not written with this patchwork of clean/contaminated material in mind. To add to the mix, the Corps of Engineers also has authorized navigation channels in many of the Commencement Bay waterways, and these are subject to specific Corps policy on dredging within Superfund sites. EPA Region 10, Seattle District USACE, the various responsible parties and their consultants have navigated years of muddy waters in the regulation of dredging and dredged material in Commencement Bay. A number of innovative (but legal) approaches have been used to comply with the law and move the clean up forward.

The U.S. Environmental Protection Agency has selected a remedy involving environmental dredging as well as natural recovery capping in this 2,440-meter (8,000-foot)-long waterway in Tacoma, Washington. The dredged material will be disposed of in a nearshore confined disposal facility (CDF) in the nearby St. Paul Waterway to create substantial new upland and intertidal habitat on the bayward face of the CDF closure berm. The dredging design calls for cuts of as much as 4.6 meters (15 feet) and intricate slope and waterfront rehabilitation. The design was completed in early 2002. This work is expected to be the first major in-water Superfund remediation project in Commencement Bay since the dredging of the Sitcum Waterway and filling of the Milwaukee Waterway in 1994.

The Middle Waterway, located in Tacoma, Washington, is approximately 3,500 feet long and is typified by areas utilized for both waterway commerce and critical fish habitat. The Middle Waterway Action Committee (MWAC) has completed pre-remedial design and a remedial options analysis for cleanup of the Middle Waterway. Working under the US Environmental Protection Agency (EPA) Superfund program for the Commencement Bay Nearshore/Tideflat Superfund Site, the remediation plans approved by EPA include dredging, thin-layer capping, and natural recovery. Approximately 90,000 cubic yards of dredged material from the mouth of the waterway will be disposed of in the Blair Slip 1 nearshore confined disposal facility (CDF), together with sediments from the Hylebos Waterway, to support economic development by the Port of Tacoma. Due to listing of several fish species under the Endangered Species Act (ESA) as threatened or endangered, the remediation plans were designed to support the remediation of contaminated sediments, the protection and creation of critical habitat to support salmon recovery, and waterway commerce. The successful integration of these potentially divergent objectives has been key to support by EPA, industry, resource agencies, and public interest groups. Final design plans are expected to be approved by the summer of 2002, with remediation commencing in late 2002 or late 2003, depending on the time frame for consent decree negotiations and construction of the Blair Slip 1 CDF.

The City of Tacoma (City) is located around the estuary created as the Puyallup River meets Commencement Bay on the Puget Sound in Washington State. The City has committed to constructing, monitoring and adaptively managing 5 habitat restoration projects in Commencement Bay, three of these projects are the topic of this paper: the Middle Waterway Restoration, the Tahoma Salt Marsh Restoration, and the Olympic View Restoration. These three projects involve cleanup of contaminated soils/sediments and creation of new intertidal habitat surfaces to support native species, including salmonids recently listed under the Endangered Species Act. Historically, the Commencement Bay / Puyallup River Estuary included thousands of acres of mudflat and fringing marsh habitat. Dredge and fill programs reduced the acreage of habitat by over 90% to create waterways and adjacent uplands for commerce and industry. Development of Tacoma's industrial base in the late 19th and 20th centuries also led to the contamination of sediments in the waterways and associated uplands. Impacts from this development have contributed to the decline of native species of plants and animals. The City's restoration projects are intended to cleanup and restore 14 acres of this estuarine habitat with a primary focus on juvenile salmonid rearing.

This paper summarizes modeling efforts to assess impacts associated with contruction and operation of Sub-channel Placement Cells (SPCs) in Newark Bay. The Port Authority of New York and New Jersey (the Port Authority) is planning to develop five SPCs for unsuitable dredged material. The SPCs would provide a capacity to accommodate approximately 10 million cubic yards of dredged material over an estimated 20-year period. Individual cells would vary in size and capacity depending upon location and depth to bedrock. Materials placed in the SPCs would be dredged from Newark Bay, the Arthur Kill, and the Kill van Kull. The modeling work was performed in connection with an Environmental Impact Statement (EIS) for this project.

This paper describes an application of the Capping Analysis Program (CAP) model to a proposed New York contained aquatic dredged material disposal (CAD) site. A number of proposed CAD facilities in 20 ft of water were considered, ranging from 40 to 60 acres in area, 40 to 60 ft of dredged material, and 3 to 10 ft of capping thickness. CAP has been developed by ERDC-WES to predict long-term movement of contaminants through caps at CAD sites. CAP incorporates a revised version of the RECOVERY sediment-water interaction model and consolidation-induced advection predictions generated from results of the Primary Consolidation, Secondary Compression, and Desiccation of Dredged Fill (PSDDF) model. Results indicated that the contaminated sediment layer would consolidate to roughly half of its initial thickness over a period of decades. New York sediments contain a number of contaminants. Copper was determined to be the contaminant of concern (COC) for its potential water quality impact based on its concentration, ability to partition to the water phase, and the magnitude of its water quality standard. CAP was run to predict the contaminant fate. Water and copper were predicted to move through the cap due to consolidation-induced advection. The simulations show that fluxes from the dredged material peak shortly after the initial consolidation and decrease thereafter. The ambient sediment at the CAD site has an elevated copper concentration, but is only a fifth of copper concentration being placed in the CAD facility. Long-term simulations for the background and the proposed CAD pit show less total flux from the pit than from the background.

The Ross Island investigation provides a case study for evaluating confined aquatic disposal (CAD) as a permanent disposal method for contaminated dredged material. Between 1992 and 1998, the Port of Portland (Port) disposed of dredged material in five CAD cells within Ross Island Lagoon, an active aggregate mining facility in the Willamette River at Portland, Oregon. Each disposal cell contains a few thousand to nearly 76,000 cubic meters (100,000 cubic yards) of maintenance-dredge material from various Port docks and slips. Although the Port received regulatory approval for disposal, subsequent regulatory and public interest led the Port to evaluate the disposals relative to human and environmental health and safety. The challenge faced by the project team was to evaluate possible human health and environmental risks several years after the dredged materials had been disposed. These challenges were compounded by the site operator's active reclamation and mining activities near the CAD cells in the intervening years.

This paper summarizes various engineering alternatives that were examined for the Port of New York and New Jersey as part of the dredged material management program (DMMP), a comprehensive investigation led by the U.S. Army Corps of Engineers, New York District. Three categories of engineering alternatives for the harbor are described, namely artificial islands, subchannel/subaqueous placement cells, and sedimentation minimization measures. Design, costs and other issues are presented.

The Dabhol Power Project in 1997 was the largest foreign investment project in India. The Project was planned to have over 2000 Megawatts of power generation, an LNG terminal, and an all weather harbor to receive fuel deliveries. The site was located on the exposed Malabar Coast of India nominally 160 kilometers south of Mumbai. The green-field development included an eight kilometer dredged channel and turning basin, a 1750 meter long unloading pier, and 2300 meters of rubble mound breakwater to protect the channel, turning basin, and berth. The purpose of this paper is to discuss the development and execution of the dredging project at the site ranging from initial site investigations through project construction and the first year's experience with sedimentation at the site.

The U.S. Navy in Pearl Harbor, Hawaii has developed an upland dredged material disposal facility on Waipio Peninsula for management of dredged material from the Pearl Harbor Naval Complex that has been determined to be unsuitable for ocean disposal. This paper presents the approach and results for the detailed evaluation of the environmental effects of dredged material management in the Waipio confined disposal facility (CDF) in accordance with the USACE/EPA "Technical Framework". The framework consists of physical and chemical characterizations and contaminant pathway testing and analysis for the selected confined disposal facility. Modeling is performed to support design/ management/operations decision-making and contaminant pathway analysis. The results of the study showed that disposal of Pearl Harbor dredged material in the Waipio CDF would be technically feasible and poses no significant impacts on human health. Potential contaminant releases by effluent, runoff, plant uptake, and animal uptake pathways represent small environmental impacts that should be acceptable with proper operation, management and controls. Copper, arsenic, and ammonia concentrations in the effluent and runoff exceed water quality standards for chronic toxicity, but, except for ammonia, are similar to the contaminant concentrations in background site water. Plant and animal uptake of cadmium, copper, and lead from the dredged material in a CDF are expected to be elevated over that of the present uptake from site soils, though still low. Controls can be implemented to limit contaminant uptake by plants and foraging animals.

Confined disposal facilities (CDFs) are one of the most widely used options for placement of contaminated sediments. Consideration of pathways for migration of contaminants from the site and potential contaminant impacts is required to determine the need for operational or engineered measures to control contaminant releases. The pathways of concern for CDFs include effluent discharges to surface water during filling operations, rainfall surface runoff, leachate into groundwater, volatilization to the atmosphere, and direct uptake by plants and animals on site and subsequent cycling through food webs. During the 1980s and 1990s, a number of evaluation procedures and laboratory tests were developed for CDF pathway evaluations, and these approaches were applied at a number of projects. However, a comprehensive approach for pathway evaluations, considering the level of concern for each pathway and an appropriate level of effort to address the concerns has been lacking. Recently, a tiered approach has been developed for CDF contaminant pathway evaluations, similar to that long used for evaluation of open water placement of dredged material. This tiered approach is being incorporated into a new testing manual for nearshore and upland CDFs, commonly referred to as the "Upland Testing Manual." The Tier I evaluation for CDFs determines the need for pathway evaluations, pathways of concern, contaminants of concern, and which pathways require more detailed evaluations based on existing information. Tier II focuses primarily on screening evaluations and chemically based tests and evaluations. The screening evaluations consist of determining the need for management actions derived from very conservative techniques which use the chemical, physical and biological characteristics of the dredged material and basic information about the CDF. Tier III focuses primarily on definitive evaluations, including pathway testing. Tier IV, which should rarely be needed for navigation projects, includes formal quantitative risk assessment designed to answer specific, well defined questions. This paper describes the tiered evaluation approach and associated testing and modeling procedures for CDFs in the context of the new testing manual.

Evaluation of water quality impacts is a critical component of the federal and state permit applications required for the construction of nearshore confined disposal facilities (CDFs). Effective evaluation must consider both short-term impacts due to dredging and placement of material in the nearshore CDF, and long-term impacts as a result of groundwater movement through the CDF. Physical and chemical characterization of the sediments and characterization of water quality in the dredge and disposal areas are used to conduct qualitative and quantitative assessments of water quality impacts. These assessments involve testing procedures developed by the United States Army Corps of Engineers' (USACE) Waterways Experiment Station (WES) and include the dredging elutriate test (DRET) and the thin-layer column leaching test (TCLT). Using a case study, this paper describes the short-term and long-term water quality impact evaluation process, including key elements of a sediment and water quality sampling and analysis plan, and appropriate test methods and interpretation procedures.

Contaminated dredged material is often placed in confined disposal facilities (CDFs) designed and operated to control environmental impacts of the disposed sediment. A CDF is a diked enclosure having structures that retain dredged material solids. When contaminated dredged material is placed in a CDF, contaminants may be mobilized to form leachate that may be transported to the site boundaries by seepage. The purpose of this paper is to present the results of sensitivity analyses of the impacts of contaminant and foundation soil characteristics on leachate transport to the water table below. The main factors affecting leachate production and transport out of the facility through the vadose zone are evaluated to develop guidelines to assist in decision making regarding the use of leachate controls. The factors evaluated relate to contaminants in the CDF and the vadose zone properties. The results highlight the significant parameters upon which leachate screening should be based. Estimates of peak contaminant concentrations reaching the water table are developed for use in leachate screening applications. Further, an equation for the time of travel of contaminants through the vadose zone is developed to compute the time it takes peak contaminant concentrations to reach the water table.

The Detroit District, Corps of Engineers is responsible for 95 navigation projects on the Great Lakes in the States of Michigan, Wisconsin, and Minnesota. The District has been using Confined Disposal Facilities (CDFs) for placement of contaminated dredged material since the 1970s. Several harbors are contaminated with heavy metals and PCBs and most of this material has been placed in the CDFs during that time. Continued dredging and lower contaminant loading into the waterway system has resulted in cleaner dredging material being placed in the upper layers of many CDFs more recently. In addition, the Detroit District is reviewing alternatives to enhance biodegradation, to optimize capping requirements and to reduce exposure pathways at several CDF sites.

The paper will describe (1) the evolution of the current guidelines from earlier versions adopted in 1986 and 1993 under the Oslo Convention and also from the Dredged Material Assessment Framework of the London Convention adopted in 1995; (2) the potential implications of Annex V; and (3) the changing approach to assessment, in particular the move towards more reliance on biological assessment of material proposed for disposal at sea rather than just chemical assessments.

The Port of Hamburg has developed a dredged material management concept based on different elements. Since the quality of the River Elbe improved very much in the last decade open water disposal or sustainable relocation of dredged sediments is now the main constituent. But still land treatment and disposal are necessary. Each year an amount of 1.4 Million m³ is technically treated in a large scale plant (separation and dewatering) and disposed in specially constructed silt mounds. Beneficial use is an aim, but until now mainly due to high costs is not sensible for very large amounts. More and more a river basin management concept which combines dredged material handling and source control to solve contamination problems at emission sources is needed.

Dredging of waterways, which is of vital importance for the economy, ecology and water management in the Netherlands, is in arrears. The main reason is the invisibility of the problem, which has lead to a lack of financial means. Moreover, in our densely populated country, possible destinations for dredged materials have become scarcer and more expensive. The present situation calls for a coherent and sustainable strategy for dredged materials in the near future. For this purpose a project to arrive at a Dutch Master plan was carried out. The main objective of the project is to make proposals for solutions and required measures, in co-operation with all parties concerned, which is used as a basis for political decision-making. The Master plan has led to the following major conclusions and recommendations to the Dutch government: A substantial increase of budgets (more than double) is needed to remove the arrears, for which a period of 25 years is envisaged. Better coordination of the dredged materials and the joint use of disposal sites and treatment plants to reduce costs. Facilitation of more destinations for dredged materials such as the promotion of treatment and beneficial reuse and adaptation of legislation.

This paper gives an overview of the work of the PIANC working group ENVICOM 5. The task of this Working Group was to establish Environmental Guidelines for Confined Disposal Facilities for Contaminated Dredged Material. These guidelines are published in April of 2002. The realisation and construction of a Confined Disposal Facility (CDF) is a complex and not standard process. In this process of the realisation of a CDF a lot of different fields of expertise have to be considered like civil engineering, landscaping, chemistry, legislation, social impact, environmental engineering and so on. Every case is unique and there are no simple answers. In order to give guidance and to show existing experiences, the Environmental Committee of PIANC gave this working group the task to give a compact and clear overview over the common practise and experiences. The different types of Confined Disposal Facilities, from aquatic disposal to land disposal are dealt with. The special subject is the containment of contaminated dredged material. This means that special measures are taken to avoid potential releases to the environment. The starting point is that the decision to make a CDF is already been made.

The Diagnostic Modeling System (DMS) provides engineers engaged in the planning, design, and maintenance of navigation channels and waterways with a structured methodology to identify, classify, analyze, and address problem shoaling areas. Jointly developed by the U.S. Army Engineer Research and Development Center and Taylor Engineering, Inc., the DMS seeks to reduce future O&M expenditures by addressing the root cause of persistent "hot spot" channel shoaling areas where the frequency and volume of dredging are considered excessive. The DMS concept embodies the rapid application of existing knowledge to facilitate focused, effective analysis to yield significant cost savings. Ultimately, the DMS develops experience-based and proven solution alternatives — all within a single dredging cycle. This paper describes the DMS and its three components — the Manual, the Data Manager, and the Analytical Toolbox. Specifically, the Data Manager is a customized GIS-application that helps users organize project information in a single location. The Data Manager also includes several analysis tools that are useful in gaining a deeper understanding of a project's history and current condition. The paper presents an overview of the DMS and several recent example applications of the Data Manager to projects within the South Atlantic Division of the U.S. Army Corps of Engineers.

This paper describes the application of the Diagnostic Modeling System (DMS) to examine the shoaling "hot-spots" within the Jacksonville Harbor Project. The paper demonstrates effective application of DMS concepts and methodology in determining the causes of the shoaling and recommends solutions to reduce the frequency and cost of dredging. Additionally, the paper details the application of DMS concepts to examine the effectiveness of advance maintenance areas for reducing channel maintenance and training wall structures for improving navigational safety.

This study was conducted to understand the causes of entrance channel shoaling at St. Marys Entrance, Florida and to develop alternatives for reducing the frequency and cost of dredging. Diagnostic Modeling System (DMS) methodology was applied to complete the study. The DMS methodology facilitated identification of excessive shoaling areas, gave insight into the causes of shoaling, and aided in development of management strategies for the channel. The analysis documented two areas of shoaling, one in the inner channel, near the seaward end of the jetties and the other in the outer channel, just seaward of the ebb shoal. The inner channel shoaled about 5,700 cu yd/year/200 ft and the outer channel shoaled about 12,000 cu yd/year/200 ft. The inner channel also had a small area of severe shoaling due to sand wave migration into the channel. A localized channel widener is suggested for the inner channel, and advance dredging is recommended for the outer channel.

This paper presents results of a coastal and inlet processes study performed to develop alternatives for reducing the cost and frequency of dredging at the mouth of the Colorado River Navigation Channel, Texas. The river had discharged into the Gulf of Mexico until July 1992, when it was diverted at a point some 6.5 miles north of the mouth to empty into (West) Matagorda Bay. As a result, river flow from the diversion point to the mouth was eliminated, the tidal prism was reduced, and unanticipated excessive shoaling of the channel entrance occurred. An innovative weir jetty and impoundment basin constructed to accommodate the anticipated increased deposition have not functioned satisfactorily. This study identified modifications to reduce and manage the entrance channel shoaling. The modifications will be implemented incrementally based upon in-course evaluation.

An adaptation of the classical inventory system model of operations research is suggested for planning and scheduling maintenance dredging operations in navigation channels. In the sediment inventory model (SIM) that results, the costs of periodic and advance maintenance dredging are set against the economic and safety implications of sediment encroachment into the channel. Among SIM variations, the situation when sediment rates are constant and dredging costs reasonable to predict, optimal dredging plans, costs and schedules may be determined by mathematical techniques such as differential calculus. Properly formulated, the resulting SIM models yield least-cost solutions and also reveal optimal relations between competing costs and alternative criteria such as safety and navigation efficiencies. When sediment rates are probabilistic and dredging costs uncertain, the stochastic SIM variant may provide useful insights into appropriate dredging policies and risks of encroachment. Through examples, this paper illustrates the results of the basic SIM variants as they apply to maintenance dredging, and suggests extensions and limitations of the model to such complexities as lead-time scheduling of dredging equipment.

This paper summarizes the July 2001 monitoring survey, which evaluated the condition of the caps and biological recolonization more than one year after their completion in the nine Boston Harbor CAD cells. Results suggest the condition of the caps in the majority of the cells remains similar to that detected immediately following the completion of capping. In cells where a relatively thick, discrete cap was initially placed, the cap continues to maintain its integrity, while earlier cells with layered cap material and DM, continue to display stratification. Benthic habitat quality was assessed over the CAD cells for the second time since initial construction of the cells. Current benthic conditions are consistent with the ambient Boston Harbor sediments not subjected to dredging operations.

New London Harbor is a major commercial, recreational, and military port in New England. Infrastructure improvement projects within the harbor have often been driven by the changing draft requirements of military vessels operating out of the US Navy Submarine Base in Groton, Connecticut. Sediments removed as part of deepening projects are transported to the New London Disposal Site (NLDS) in eastern Long Island Sound and deposited on the seafloor. In 1995, the US Navy selected the Groton Submarine Base in the Thames River, Connecticut as the homeport for the new Seawolf class submarines. In order to accommodate these larger vessels, improvement dredging was required within both the federal navigational channel and multiple submarine berths. Pre-dredging characterization of the project sediments detected polycyclic aromatic hydrocarbon (PAH) and trace metal (Cu, Cr, and Zn) contamination in a portion of the dredging area.

In 1995–96, an estimated 305,000 m³ of unacceptably-contaminated dredged material (UDM) was placed on the open seafloor at the New London Disposal Site (NLDS) in eastern Long Island Sound and subsequently capped with approximately 556,000 m³ of clean capping dredged material (CDM) to form the Seawolf Mound. As one component of a comprehensive environmental monitoring program, multiple surveys have been conducted to assess recolonization of the Seawolf Mound by benthic macroinvertebrates. Sediment grab samples for benthic taxonomic analysis were collected at six stations across the capped mound in September 1997 (1.5 years following completion of the capping operation) and June 2001 (5 years postcap). REMOTS sediment-profile images were collected simultaneously at the six stations in both years, as well as in July 1998 and August 2000. Both monitoring techniques indicated progressive recolonization of the mound over the five-year postcap period, consistent with expectations. By September 1997, the mound had become colonized by a benthic assemblage dominated by moderate numbers of surface-dwelling organisms indicative of early-to-intermediate successional stages (Stages I and II). Numbers of species and individuals both increased with distance from the center of the mound, reflecting a gradient in the degree of physical disturbance associated with the cap material placement. The subsequent surveys of July 1998, August 2000, and June 2001 indicated further increases in numbers of species, organism abundance, and diversity, with significantly higher numbers of advanced Stage III taxa collected in June 2001. Benthic recolonization over the surface of the mound was at an advanced, "equilibrium" stage five years following completion of the capping operation, consistent with predictions based on established successional models for Long Island Sound.

The overall objective of the MBDS capping demonstration project was to evaluate the effectiveness of subaqueous capping as a dredged material management technique at this deep-water disposal site. A series of monitoring surveys employing precision bathymetry, side-scan sonar, sediment-profile photography, and multiple sediment collection techniques were performed over the study area to track the development of the capped mound. The comprehensive data set documented the development of a capped mound composed of two distinct layers of sediment on the MBDS seafloor. This paper will discuss the success of the demonstration project, a recommended approach for future deep-water capping projects, and the value of firm, cohesive glacio-marine clay as a capping/armoring deposit.

The Great Lakes Dredged Material Testing and Evaluation Manual (Manual) is formal guidance promulgated by a joint U.S. Environmental Protection Agency (USEPA)/U.S. Army Corps of Engineers (USACE) task group to provide protocols for the testing and assessment of dredged material proposed for discharge into United States (U.S.) waters of the Great Lakes, in accordance with the Guidelines of Section 404(b)(1) of the Clean Water Act (40 CFR 230.10). Founded on national guidance contained in the Evaluation of Dredged Material for Discharge in Waters of the U.S. - Testing Manual, it is a regional manual commissioned for the Great Lakes. Although the Manual was not finalized until 1998, the guidance contained therein has essentially been applied to Great Lakes dredged material since at least 1993. The protocols provide for a three to four-tiered system that utilizes existing environmental information, sediment and water chemistry, modeling and effects-based biological testing to ascertain the suitability of dredged material for disposal at open-water sites in the Great Lakes. Application of the guidance in the Manual to USACE dredging projects in the Great Lakes has met with reputable success and it has ensured that the open-water disposal of dredged material is appropriate and protective of the aquatic environment. Nonetheless, certain aspects concerning the application of the Manual may also be problematic, and specific cases are presented and evaluated to identify the potential need for clarification or improvement. These intricacies may be project-specific, protocol-oriented or speculative in nature, and have been grouped into five focus areas. First, sampling and testing, and utilizing the data from potentially non-representative disposal/reference areas, is discussed. Second, the elucidation and use of confounding or conflicting bioassay test results are addressed. Third, the use of the default biota-sediment accumulation factor (BSAF) in the theoretical bioaccumulation potential (TBP) model is evaluated. Fourth, the relevance and value of data generated from bioaccumulation tests for sediment metals is discussed, and some inconsistencies on the interpretation of bioaccumulation data are presented. Fifth, instances where States use other dredged material guidelines, policies and standards are discussed with respect to their association with the guidance contained in the Manual. In addition, the overall reception of the Manual by several State regulatory agencies is reviewed. Recommendations are offered on how to clarify or advance the Manual in these areas in order to make its application more effectual.

Milwaukee Harbor and the Fox River/Green Bay Channel have been primary focus areas for the U.S. Army Corps of Engineers and the U.S. Environmental Protection Agency's Great Lakes National Program Office in attempts to develop beneficial uses for dredged material. Studies have focused on low-cost treatment alternatives that could be implemented at the dredged material disposal facilities to enhance the degradation of contaminants and produce a marketable product. The goal of the program is to convert dredged material confined disposal facilities to handling facilities where dredged material could be dewatered, screened, mixed with amendments, phytoremediated, composted, and stockpiled as necessary before eventually being moved off-site for beneficial uses. Pilot scale studies have included attempts to compost the dredged material and to evaluate its marketability as a topsoil or topsoil amendment. Mixtures from the composting study were tested in the greenhouse for comparison to commercial topsoil mixtures. A marketing study evaluated the potential demand for a treated dredged material product in the Milwaukee and Green Bay areas and identified several potential customers for the dredged material-derived topsoil. The results presented suggest that dredged material can be treated on confined disposal facilities and that topsoil created from dredged material could be a marketable product. Efforts to treat remaining PCBs in the dredged material have been more successful than the treatment of PAHs. Conclusions from this research and others suggest that the PAHs in the dredged material topsoil may not be bioavailable and therefore may not be a concern. This paper will discuss the lessons learned with these pilot scale efforts and will discuss concerns with the long-term management of dredged material.

This paper provides an overview of the Green Book testing regime, focusing on evaluation of risk and compares the results of synoptic testing of sediments from three harbors in the Northeast. First, sediment chemical concentrations from the three locations are compared to established sediment quality guidelines (SQGs). Next, biological effects tests, including the 10-day toxicity tests using Ampelisca abdita and Americamysis bahia are conducted to determine the potential for "adverse effects." Finally, 28-day bioaccumulation tests using Macoma nasuta and Nereis virens are used to assess contaminant mobility. Alone, these tests only assess exposure and not the potential for adverse effects-from COCs to higher trophic levels. For this reason, a risk-based approach is also used to evaluate the potential for ecological and human impacts from exposure to contaminated sediments. Risk-based evaluations, performed on bioaccumulation data from the 28-day tests, were conducted and the results are evaluated in the context of the standard evaluations for suitability of dredged material disposal in open waters. This "risk-based" approach to evaluate disposal options allows an effective management strategy, which minimizes environmental effects.

The purpose of this paper is to systematically explore the utility and relevance of current regulatory guidance involving environmental investigations, and to suggest ideas for the development of a more consistent set of evaluations that are protective of the environment. Selected national and regional guidance documents are evaluated to determine whether species selection and test recommendations are applicable and appropriate to safeguard environmental quality. National guidance manuals include EPA/USACE publications associated with dredged material testing in marine, estuarine, and freshwater environments; regional practices include current guidance for New York (NY Regional Testing Manual) and for Puget Sound, Washington (PSDDA).

In 1989, the San Francisco Bay became "mud locked" over environmental concerns of dredging and dredged material disposal. One of the in-bay disposal sites was physically blockaded by a flotilla of fishing boats and other vessels and dredging in San Francisco Bay was temporary halted. Therefore, in 1990 the U.S. Army Corps of Engineers initiated a long-range interagency planning process for dredged material management for the San Francisco Bay. This effort resulted in the Long Term Management Strategy (LTMS) for the Placement of Dredged Material in the San Francisco Bay Region. This Paper presents a history of some of the events leading up to the crisis, the development of the LTMS plan and the actions now being taken to implement this program. It also discusses the importance of consensus building, some of the lessons learned and what has worked best during this process.

The Dredged Material Management Program is a cooperative interagency program in Washington State for regulating and managing dredged material in Puget Sound, in Grays Harbor/Willapa Bay, and in the Lower Columbia River. Each of the four cooperating agencies (U.S. Army Corps of Engineers, Seattle District (lead agency); U.S. Environmental Protection Agency, Region 10; Washington State Department of Ecology; and Washington State Department of Natural Resources) has jurisdiction over dredging and disposal of dredged material. The effort to develop a new interagency program to manage dredged material began in 1985 in Puget Sound. Called the "Puget Sound Dredged Disposal Analysis" (PSDDA) Study, it was developed over a 4.5 year, two-phased cost shared study for $4.5 million dollars. The study brought the federal and state regulatory and resource agencies, environmental interest groups, and the public together through a consensus process. Two overlapping Environmental Impact Statements developed state-of-the-art evaluation procedures, identified environmentally acceptable disposal sites, and developed site-specific monitoring plans to assess the success of management objectives. In 1995 the interagency model for PSDDA was extended to the coastal Washington estuaries in Grays Harbor and Willapa Bay, and in 1998 to the lower Columbia River. The evaluation procedures developed for these two areas was conceptually patterned after the PSDDA evaluation procedures, with modifications that reflected local hydrodynamic conditions and chemicals of concern. Upon completion of the dredged material management manuals for these three diverse water bodies, the interagency program established to implement them became the "Dredged Material Management Program".

The recently initiated USACE feasibility study for the Hudson-Raritan Estuary Ecosystem Restoration Project has as its cornerstone four major methods of restoration proposed for New York/New Jersey Harbor. These are: 1) the removal of millions of cubic yards of upland fill to restore wetland and shallow water habitat, 2) the removal or modification of structures (e.g. bridges and causeways) that block tidal flow, 3) the construction of artificial reefs, and 4) the dredging and/or recontouring of contaminated sediments to restore benthic habitat and improve water quality. The NY/NJ Harbor ecosystem has experienced significant water quality improvement and the return of certain species in the past few decades; however, the sediments and associated benthic organisms in many areas are still highly contaminated. Improvement in estuarine benthos lags significantly behind water column improvements, and many areas may never improve significantly without additional help in the form of dredging and recontouring. Several dredging/recontouring projects throughout the Harbor have been proposed and baseline studies to characterize the physical, chemical and biological characteristics of selected study sites are currently underway.

The 2,400-meter (8,000-foot)-long Thea Foss Waterway in Tacoma, Washington, is undergoing a U.S. Environmental Protection Agency Superfund cleanup to address sediment contamination. Seepage of coal tar-like non-aqueous phase liquid (NAPL) and related polycyclic aromatic hydrocarbons (PAHs) near the head of the waterway presents an especially problematic condition that if not controlled will in time lead to recontamination of sediment. Batch and column treatability testing was conducted using several sorbent materials and NAPL and sediment from the waterway to confirm that the remedial objectives could be met and to develop empirical-based design parameters. The composition and dimensions of the sorbent cap were selected based on U.S. Army Corps of Engineers protocols for subaqueous capping, field and laboratory test results, and performance modeling. The Thea Foss Waterway application will be the first time this technology is used for NAPL remediation.

The Whatcom Waterway Site, located within inner Bellingham Bay, Washington consists of intertidal and subtidal aquatic lands within and adjacent to the Whatcom Waterway in Bellingham, Washington. Georgia-Pacific completed a Remedial Investigation/Feasibility Study (RI/FS) of the Whatcom Waterway Site in July 2000 under Washington State's Model Toxics Control Act. This study found that the Georgia-Pacific Log Pond contained elevated concentrations of mercury, phenolic compounds, and woody debris that exceeded State cleanup levels. In cooperation with the Washington Department of Ecology and the Bellingham Bay Pilot Team, Georgia-Pacific developed the Whatcom Waterway Log Pond Interim Remedial Action and Habitat Restoration Project, in which approximately 43,000 cubic yards of clean navigational dredge material were placed on the Log Pond sediments between November 2000 and February 2001. The final total placed thickness of the Log Pond cap ranged from 0.5 feet along the cap perimeter (e.g., adjacent to structures) to up to 10 feet within the interior of the project area. The combined capping and habitat restoration project also improved 5.6 acres of habitat within the Log Pond. Long-term monitoring of the cap is underway, and results of Year-1 monitoring are discussed, including: 1) monitoring of seepage quality at the margins of the Log Pond cap to demonstrate protection of surface water; 2) Sediment monitoring within the Log Pond to demonstrate compliance with State cleanup levels; and 3) Biological monitoring within the Log Pond area to demonstrate ecosystem restoration and the protectiveness of the cap in controlling bioaccumulation exposures.

Dredging, by its very nature, causes an environmental impact. The relative scale of the impact is a function of many factors including the dredging operation, the hydrography of the area and the sensitivity of the site. During the last two decades, environmental impact was often measured by the immediate and long-term impact on flora and fauna at a species level, but regulators and environmentalists alike now feel that the optimum way of protecting single species is to sustain the health and balance of a habitat. Determination of environmental impact by measuring biological effects can be costly, long term and inconclusive leading to considerable debate between port management, regulators and environmentalists. If dredged sediment never actually reaches a sensitive site or is only deposited at levels well below natural ambient then long-term biological monitoring is at best likely to lead to further monitoring over a longer period and increased costs. It is proposed that significant cost-savings can be made and delays for port developments reduced if, initially, physical effects are monitored and understood and the data used to relate to biological impact or focus in on the specific needs for any biological monitoring that is required. The use of sediment tracers coupled with a standard suite of marine survey techniques provides tangible data on sediment transport rates and deposition in order to assess environmental impact.

This paper reviews the current understanding of ghost shrimp natural history on the west coast of North America including preferred habitat types and bioturbation activities. From this information, cap design criteria and guidelines to protect against ghost shrimp bioturbation are presented that can be applied to a variety of capping situations. Design criteria and guidelines include: required cap thickness in various situations, water depths and environments that often have high rates of ghost shrimp bioturbation, and cap materials that reduce or prevent ghost shrimp burrowing activities or maximum depths. For cap thickness guidelines, the importance of differentiating between bioturbation that causes significant sediment turnover and observations of maximum ghost shrimp burrowing depths is also discussed. Natural history information is also used to better define reasonable requirements for long term monitoring of ghost shrimp presence and activities at capping projects.

To date, dredging has been the primary remedial option selected to address contaminated sediment sites. Experience from these completed projects provides invaluable insight into the effectiveness of environmental dredging in reducing risks to both humans and environmental receptors. Actual data from completed projects will be used to help illustrate and support the lessons learned and conclusions regarding the effectiveness of environmental dredging.

The backbone of DRAMA is the Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES). FRAMES is a multi-stage object-oriented, PC-based environment for integrating exposure and effects models and databases to perform human health and ecological risk Characterization and uncertainty quantification in multi-media. DRAMA is the integration of ADDAMS and dredging effects databases with FRAMES. To facilitate rapid application of DRAMA and aid in problem formulation, pre-set assessment scenarios for common dredging and disposal operations are incorporated as conceptual models of the contaminant exposure sources, pathways, and receptors. The pre-set scenarios include selection of exposure pathway models, exposure effects databases, and risk characterization tools and provide linkages between the components. Example pre-set scenarios are no-action, dredging, open-water disposal, capping, and upland disposal. DRAMA will make the decision process more explicit, facilitate uniform application of risk models, perform risk assessment quantitatively, and provide probabilistic description of risk and uncertainty.

Contaminated sediments, particularly those containing chlorinated hydrocarbons such as dioxins, pose a potential threat to the environment and human health arid significantly affect the U.S. Army Corps of Engineers navigation dredging program, causing significant project delays and management cost increases. Contaminated sediments unsuitable for conventional disposal may be confined, contained, treated, or simply not dredged. Research under the USACE Dredging Operations and Environmental Research (DOER) program is underway to address the most pressing problems related to contaminated sediments management. The objective of the Contaminated Sediments Focus Area under DOER is to reduce cost and improve the reliability and acceptability of dredging, placing, managing, and controlling contaminated dredged material. The research addresses aspects of the problem related to screening, assessment, and management, with emphasis on those solutions most applicable to the navigation-dredging program. Screening efforts include development and verification of methods for low-cost, rapid, and interpretable biological screening methods to reduce the number of chemical analyses, and quickly identify contaminated sediments and marginally contaminated dredged material. Improved screening procedures are also being developed for contaminant pathway evaluations. Assessment efforts are mainly concerned with field verification of contaminant pathway and biological testing approaches for contaminated sediments developed under other research programs such as the USACE Long Term Effects of Dredging Operations (LEDO) program. The management options most often used for contaminated sediments from navigation projects are Confined Disposal Facilities (CDFs) and subaqueous capping. Significant work is underway for management of contaminated dredged material in CDFs including contaminant control, treatment, and removal technology and reuse of marginally contaminated sediments from existing confined disposal facilities (CDFs). This paper provides an overview of the DOER Contaminated Sediments Focus Area, a description of the research efforts underway, and how the completed research benefits the USACE navigation dredging program.

The Dredging Operations and Environmental Research (DOER) Program at the Engineer Research and Development Center — Waterways Experiment Station is conducting research directed at reclaiming confined disposal facilities (CDFs) for dredged material. Reclamation research is being conducted on four fronts: soil separation, bioremediation, phytoremediation, and manufactured soil. The ultimate goal is to recover storage capacity in CDFs by converting CDFs to rehandling and treatment facilities for beneficial use of dredged material. DOER products that address dredged material characterization for beneficial use and implementation of a beneficial use plan for dredged material in CDFs are discussed. On the soils separation front, DOER products include technical notes that describe separation concepts, methods for calculating volumes of recoverable material meeting beneficial use requirements, data acquisition requirements, and statistical methods for sampling and data interpretation. The DOER bioremediation work unit has focused on field demonstrations of composting and land treatment technologies. Land treatment was especially effective for removal of PCBs from dredged material. Composting was partially effective for PCB removal. Phytoremediation is another potentially effective and affordable means of decontaminating dredged material. A field demonstration using phytoremediation is underway at the Milwaukee, WI CDF, and a number of green house studies are in progress. DOER products related to trash and debris removal and potential use of dredged material as manufactured soil are discussed. Brief descriptions of various field studies are presented.

Environmental windows have become a prevalent dredging project management practice. Frequently decisions regarding windows are made in the absence of conclusive evidence that dredging does or does not pose a significant threat to specific resources. Windows are often based on a risk-averse approach, which in many cases may be over-restrictive. Given the host of factors that influence dredging-related risk, resource and dredging project managers have been handicapped by a lack of tools and methods for evaluation of the need for protective measures. Recent efforts within the Dredging Operations and Environmental Research (DOER) Program have sought to fill this gap along several fronts: development of models designed to simulate dredging processes; development of enhanced technologies for characterization of dredging-induced perturbations; and development of databases that provide access to relevant data. Among the modeling tools are SSFATE, SSDOSE, and FISHFATE, models that respectively simulate sediment resuspension and dispersion, calculate exposures of aquatic organisms to sediment plumes, and estimate the population dynamics consequences of hydraulic entrainment. The ultimate goal of these development efforts is provision of a complete "toolbox" for use by biological resource and dredging project managers, whereby environmental windows can be evaluated in terms of need and effectiveness. These tools can also be used proactively to predict the likely effects of various dredging project scenarios, such that if windows are justified, their dates can be determined to provide optimal resource protection. SSFATE is a flexible model built on a GIS platform that simulates resuspension by hopper, cutterhead, and bucket dredges. The user customizes the dredging scenario to accommodate best available knowledge of the dredging mode of operation, in situ sediment characteristics, and local bathymetry and flow fields. Output includes particle tracking plume animation in tidal and non-tidal situations and prediction of time series trajectories of suspended sediment concentration at any location in the model domain. In SSDOSE, the user can calculate the hypothetical exposure of various organisms (e.g., sessile bottom invertebrates, passively drifting plankton, adult fishes with directed movement) as they encounter plumes generated in SSFATE. With FISHFATE, the user can place estimated rates of mortality due to hydraulic entrainment into context with other sources of mortality acting upon a given stock, and predict the short and long-term consequences of multiple dredging project scenarios. Each model is capable of examining alternative dredging practices and providing insights into risk minimization via optimal windows.

Potential effects of underwater noise produced by dredging operations on a variety of organisms have emerged as a concern of environmental agencies. For example, it has been hypothesized that dredging-induced noise could block or delay the migrations of fishes through navigable waterways. Few data exist that adequately characterize sounds emitted by dredge plants that would support objective decisions balancing the need to dredge against relative risk to a fishery resource. To obtain data to address this concern, field investigations were undertaken to characterize underwater sounds typical of bucket, hydraulic cutterhead, and hopper dredging operations. Bucket dredges produce a repetitive sequence of sounds generated by winches, bucket impact with the substrate, bucket closing, and bucket emptying. In contrast, cutterhead dredges generate relatively continuous sounds as the cutterhead rotates while embedded in the substrate. Hopper dredge sounds consist of a combination of sounds emitted from two relatively continuous sources: engine and propeller noise similar to that of large commercial vessels, and sounds of dragheads moving in contact with the substrate. The intensity, periodicity, and spectra of emitted sounds differ greatly among dredge types. Components of underwater sounds produced by each type are influenced by a host of factors including substrate type, geomorphology of the waterway, site-specific hydrodynamic conditions, equipment maintenance status, and skill of the dredge plant operator. Dredge sound characterization data must be integrated with knowledge of auditory thresholds and behavioral responses of those aquatic organisms perceived to be at risk in order that potential impacts can be accurately assessed. Ultimately, should problematic effects be detected, sound characterization data can lay the groundwork for effective mitigation measures.

This paper describes how the DOER program is evaluating and bringing innovative dredging technologies to field applications at selected navigation projects. Several key innovations are reviewed and presented.

Satellite communications are being used to transfer production data in real-time from hopper dredges working under contract for the US Army Corps of Engineers (COE). These data are automatically sent to a database server for dissemination to COE dredging managers on a national basis. The data sent are similar to existing COE summary reports but are based on actual process data from the dredge and include load production data. Because hopper dredges are so highly mobile, communications technology solutions typically employed by other dredge types have proven inadequate in actual field deployment. Satellite services with higher speed, digital technology, and lower cost than previously available contribute to a real-time data transfer solution for the COE.

An Experimental mixed-sediment mound has been constructed 7 km south of the mouth of the Cape Fear River, NC. The objectives of the study include: (1) document the fate of the mound, (2) document sediment characteristics over the long term; and (3) investigate the generation of turbidity associated with the mound. Directional wave information, vertical current profiles, surface-sediment samples, suspended-sediment concentration measurements, and repetitive high-resolution bathymetric and sub-bottom surveys have been obtained since April 2001. Results to date indicate that the mound has remained intact while the mound crest may be creeping toward shore in response to the prevailing wave and current conditions. Sedimentary characteristics appear to be cyclical in response to local processes. The general trend is that over time the high concentration of fines winnow out leaving a predominantly sand pavement on the mound surface until the next storm event. In addition, turbidity levels over the mound were found to not be anomalously high in comparison to ambient levels. This study is important for model development and dredging operations implementation.

The paper will outline the approaches being adopted in Europe and in the USA and how it is hoped that they will merge to give a high quality, reliable tool for use by dredging people and regulators alike. The paper highlights the technical problems such as dynamic measurement of plumes, and processes of sediment disaggregation and entrainment. It will also show how these problems are being tackled.

Technology transfer (T2) is an integral part of any research program. As early as the planning stages, technology transfer must be given equal standing with the rest of the program's objectives. Management support is vital, as is adequate funding. The T2 manager must plan marketing and outreach activities for the program, the research staff involved in the program, and the research results. Early on, the Dredging Operations and Environmental Research (DOER) Program managers emphasized the T2 role, providing adequate funding to execute the T2 mission for the duration of the initial program. This mission was outlined in a T2 management plan. The DOER Program's Technology Transfer Plan has stood the test of time and continues to show substantial results as well as national awards.

This paper presents the National Dredging Team's (NDT) Action Agenda resulting from presentations and discussions during a public workshop in Jacksonville, Florida. The intent of the workshop was to share information about scientific and programmatic dredging issues, build partnerships to effectively execute dredged material management activities, and develop a national action agenda for management of dredged material. The Action Agenda is organized around four themes: Beneficial Use of Dredged Material, Sediment Management, Emerging Issues, and Strengthening Regional Dredging Teams.

This study will review the benefits and limitations of using in situ sondes for continuous monitoring during dredging and disposal. Alternative methods of deployment and design will also be discussed. Maps from the GIS system will be used to illustrate how these data were archived for future analysis.

Dredged material disposal is one of the biggest challenges facing most ports in the United States today. As our coastal and harbor areas continue to grow in population competition for use of waterfront property and adjacent harbor and ocean waters challenges our ability to dispose of dredged material in an environmentally appropriate and economically feasible manner. Increased sensitivity and knowledge of the impact of chemical contamination in some dredged material adds additional challenges to finding environmentally appropriate dredged material disposal alternatives in older urban ports like the Port of New York & New Jersey (the Port). This paper gives a brief history of recent dredged material disposal management efforts for the Port. It describes how other similar ports in the United States have dealt with their dredged material disposal management challenges and compares that with the current situation in the Port. Here emphasis and encouragement has been given to private sector development of beneficial uses for treated dredged material as cover material for "brownfield" or sanitary landfill remediation. This is a different approach than other ports have taken, where the public sector (federal and/or State agencies) has taken the lead in developing and managing dredged material disposal alternatives. This paper describes a new paradigm for dredged material disposal taking into account the current technologies and methods available, as well as the socioeconomic and political landscape of the Port. The future direction of dredged material management in the Port of NY & NJ needs to rely on a synergistic approach between the public and private sectors. Finally the paper compares the current situation concerning disposal management in the Port to this new paradigm.

Simultaneously with the Corps of Engineers' channel studies, the Port Authority has completed a study for terminals and intermodal connections. The analysis identifies the investments required to expand the infrastructure assets of the Port. In addition, the New York City Economic Development Corporation has also completed a study for redevelopment of the Port of New York. This study examines Port and potential terminal sites on the New York side of the harbor to maximize the throughput capacity of New York City facilities. Combined, these studies recommend an investment of $5 to $7 billion for terminal reconfiguration and expansion as well as investments for new and enhanced intermodal connections. Additional investments must be considered during the overall project's financial analyses to get a complete picture of the total port redevelopment cost and its ultimate scope. This paper describes these considerations and additional aspects in the context of the port expansion activities at the Port of New York and New Jersey.

This paper confronts the stigma that a robust economy and self-sustaining environment cannot co-exist within an estuary that contains significant ecological resources, and operates major port facilities. Even before the tragic events of September 11^th, the steady growth of the global economy and the expansion of international trade were putting intense pressure on the collective performance of the Port of New York and New Jersey and surrounding transportation infrastructure. This in turn has placed a significant burden on surrounding ecosystems to assimilate the growth, and to sustain themselves from the standpoint of ecological integrity and natural diversity.

At St. Joseph Harbor, MI, efforts have been made to secure a long-term dredged material placement plan for over 30 years. Numerous sites with seemingly strong potential have gone awry for numerous different reasons over this period. This has frustrated the local harbor board, commercial entities, local community leaders and the US Army Corps of Engineers (USACE). Although a long-term dredge material placement plan is needed for annual maintenance dredging required to keep the Federally mandated shipping lane at it's authorized and required depths, a 1990 USACE reconnaissance study also determined that deepening the harbor by two feet was economically justified. However, without a site to house the material dredged from the harbor to provide this extra depth, the study has remained inactive. Upon the local sponsor identifying a viable alternative, a detailed feasibility study may be warranted to more closely examine this potential economic enhancement project.

Historic dredging activities in Holland, MI — a Federal commercial harbor — were done by the US Army Corps of Engineers using government plant with open water, offshore disposal. In the late 1960s, the State of Michigan prohibited open water disposal for "polluted" sediments, and the community was forced to find confined disposal facilities (CDF). Windmill Island CDF and Riverview CDF were two sites in Holland that were developed for placement of dredged materials. The sites were used alternately, allowing the material to dry out prior to its next placement. The Windmill Island site was the first to reach capacity, and it was capped with topsoil, seeded, and left for the material to settle. In 1998, the Riverview site was capped. Today, Windmill Island is being developed as a commercial and residential upscale development reminiscent of the villages of the Netherlands. And, the Riverview site is now home to the Window on the Waterfront Park.

The paper/presentation will discuss the navigation mission of the Corps and the relationship of the dredging program to creating and maintaining viable port and harbor channels, and inland and intracoastal waterways. Annual quantities dredged and dollar expended and the historic trends in dredging will be examined, as will new projects recently authorized in the Water Resources Development Act of 1999 and 2000, and future challenges in the dredging arena.

It is in the National interest that the capacity of our Marine Transportation System (MTS) and associated port, rail, and highway infrastructure be improved to keep pace with the demands of trade. The criteria by which successful increases to capacity are incrementally met will be measured in terms of safety and efficiency of the entire transportation system and its impacts with the surrounds. Improvements to capacity must be implemented while respecting our environment and protecting population centers. Significant advantages for development lie within scenarios considered opportunistic for growth at each U.S. coast.

A National Dredging Needs Study (NDNS) was initiated by the Institute of Water Resources (IWR) of the USACE to investigate the adequacy of U.S. navigation channels and harbors to accommodate changes in the world merchant fleet well into the 21st century. Among the results of the NDNS was a projection of future vessel types and sizes calling at U.S. deep-draft ports, and an analysis of potential dredging needs based on these future traffic projections. A concurrent IWR study included a shipping trends impact assessment on navigation channel usage and design, based in part on the NDNS projections. This paper reviews and augments the NDNS projections with respect to changing vessel characteristics and ship designs, and discusses their impact on navigation channel design, maintenance, and the related dredging implications.

This paper examines major U.S. harbor improvements to serve the increasingly larger ships in use or on order in the world fleet. Attention is focused on select harbor projects completed or underway, including channel depths, type of traffic served (container, bulk), cost, changes in scope and why, environmental mitigation measures, and remaining work. Major future projects that have recently been authorized or are underway, such as Houston/Galveston Bay, are highlighted.

This paper examines the vital role the inland waterways play in U.S. domestic and foreign commerce. The inland waterway system allows the competitive movement of huge quantities of liquid and dry bulk cargoes between deepwater ports and distant points of production or consumption in the nation's interior. The federal government has taken the lead to develop and maintain our inland waterways infrastructure through a combination of dredging, river training works, and navigation locks and dams. But nearly half of these locks and dams now exceed their 50-year design lives. At the same time traffic has continued to grow and there is a need for larger replacement locks at many locations. Further, as the system ages the need for maintenance increases. But federal budget constraints have postponed critical maintenance. The queue of new or replacement lock projects awaiting construction continues to grow and schedules of many projects now underway are being stretched, increasing congestion and reducing project benefits. This paper focuses on concerns for the physical integrity and the decline in funding of a critical intermodal transportation link for commercial traffic between U.S. coastal ports and inland origins and destinations.

From 1997 through 2000, approximately 240,000 cubic yards of PCB-contaminated sediment and soils were removed from a 3.5 mile reach of Town Branch Creek in Russellville, Kentucky. Town Branch is a relatively small creek (i.e., about 20 – 50 feet wide, 4 –10 cfs), flowing through both urban and agricultural areas. This paper will describe the removal and restoration efforts employed along with the challenges encountered and overcome. More specifically, the methods used to remove and restore the creek bed (i.e., sediment and bank soils) and floodplain soils will be discussed. A combination of both mechanical and hydraulic methods were used to remove all sediment to the extent practical, with soils removed to certain PCB concentrations based on land use. Additional removal and restoration efforts included bypass of the creek flow to facilitate removal "in the dry", habitat restoration within the creek bed, as well as restoration of the riparian zone in the floodplain. Challenges which were encountered included difficulties in obtaining access to third party properties, the unprecedented scope of restoring the habitat (in drought conditions) which was inevitably destroyed during removal efforts, the "flashy" nature of the creek flows, as well as the irregular bedrock creek bottom in karst terrain, to name just a few. Observations and "lessons learned" from the project will be presented along with recommendations for those faced with similar projects in the future.

Hart Crowser conducted Remedial Investigations (RI) and Feasibility Studies (FS) at two active shipyards in Coos Bay, Oregon. These shipyards are located in ecologically sensitive estuarine and wetland habitats in Coos Bay, Oregon. RI/FS activities were conducted pursuant to separate Administrative Cleanup Orders issued by the Oregon Department of Environmental Quality (DEQ). We were able to avert a Superfund listing and we successfully negotiated the Cleanup Orders with DEQ so that the RI/FS activities were focused to site contaminants; the cleanup decisions were based on appropriate risk based standards; and cleanup could proceed on realistic timelines. Primary sources of contamination include current and past activities attributed to fabrication and repair of fishing vessels, ocean tugs and barges. Waste streams generated by routine site activities include spent sandblast grit, marine antifoulants from hull paints, and petroleum sludge from barge and bilge tank cleaning. Remedial Investigation activities included: delineations and determinations of surface and subsurface sediment quality, and upland soil quality; and ecological and human health risk evaluations for site contaminants of concern. Metals and tributyltin (TBT) were identified as the chemicals of concern in sediments. In upland soils, no human health risk criteria were exceeded; however, copper and nickel were identified as the primary contaminants of concern to ecological receptors. Feasibility Studies identified appropriate remedial action alternatives and source controls to eliminate current ecological risks and prevent future re-contamination of upland soils and estuarine sediments. The selected alternatives for sediments included excavation/dredging of contaminated areas along the marine ways and natural recovery of peripheral areas. Source controls included capping of soils with asphalt; improved stormwater management with filtration vaults; wash water treatment for metal removal using a flocculation system; as well as improved best management practices at the shipyards. These projects enabled the shipyards to remain economically viable and their improved work practices will protect the sensitive habitats surrounding them.

In 1995, Alcoa Inc. (Alcoa) implemented a Non-Time-Critical Removal Action (NTCRA) at a localized area within the Grasse River Study Area (Massena, New York). The objective of the NTCRA was to remove the most upstream source of polychlorinated biphenyl (PCB)-containing sediment in the Grasse River, while obtaining site-specific data for use in developing remedial alternatives for the site. Approximately 2,600 cubic yards (cy) of sediments and 400 cy of boulders/debris were removed/dewatered and disposed from the 1-acre removal area. The targeted removal area was enclosed by a triple-tiered silt containment system to mitigate the escape of total suspended solids (TSS). Boulder removal operations occurred first using a long-stick excavator fitted with a specialized bucket. Sediments within the 1-acre area were subsequently dredged using an 8-foot horizontal auger dredge. In addition, a hand-held suction dredge was used to remove a relatively small amount of material from an isolated area adjacent to Outfall 001. Water column data collected both during and after the removal operations showed that, despite the containment system's ability to significantly reduce TSS levels, approximately 5 to 30 pounds of sediment-bound and soluble PCBs did escape from the containment area. Similarly, caged fish and spottail shiner studies indicated increases in PCB bioavailability during, and immediately following, the operations.

This paper offers a protocol for using fate and transport models to evaluate the long-term effectiveness of dredging and other alternatives in reducing long term risks. The protocol addresses the following: (1) use of screening level analysis to facilitate understanding of factors controlling future risks and to guide selection of alternatives for more detailed analysis; (2) design of model simulations of dredging alternatives including representation of remedial schedules, dredging releases, and post-dredging conditions; and (3) approaches for comparative evaluation of model results.

Potential effects of dredging-induced underwater noise, suspended sediment plumes, and hydraulic entrainment have been identified as sources of concern for protection of fishery resources. Although such concerns have persisted for decades, conclusive evidence either substantiating or refuting them is lacking. One means of establishing the likelihood of actual impacts to fishery resources is examining the distribution of fishes in relation to the conduct of the dredging project. In the present study, fisheries hydroacoustic techniques were used to examine abundances and spatial and temporal distribution patterns of fishes around a hydraulic cutterhead dredging operation in a tidal reach of the James River, Virginia in October 1999. Hydroacoustic surveys were conducted during various stages of the tide on two spatial scales: several kilometers up and downstream of the dredge, and within several hundred meters of the dredge site or pipeline discharge area. Surveys were completed during periods of active dredging as well as when the dredge was idle. Gill nets were deployed to characterize the local fish assemblage and to identify acoustic targets. White perch (Morone americana), spot (Leiostomus xanthurus), and gizzard shad (Dorosoma cepedianum) accounted for almost half of all fish captures. Estimates of fish density with distance (30 m increments) from the dredge were examined for evidence of fish attraction to, or avoidance of, an operating dredge.

Following a break in a discharge pipeline from a hardboard manufacturing plant, 11,500 cubic yards (cy) of effluent solids were released into a backwater slough of the Arkansas River. A beaver dam had entrapped approximately 3,500 cy of the effluent solids and a wetland had emerged from the organically rich solids. The wetlands consisted of diverse, perennial, marsh-type vegetation that offered unique features to the region. The remaining 8,000 cy of solids were in a region of the slough which was covered with water, and due to high biochemical oxygen demand (BOD) of the solids and limited exchange of surface water in this reach, were creating anoxic conditions. Since natural assimilation of the solids did not appear to be proceeding fast enough, it was decided to remove 8,000 cy of solids from this portion of the slough.

During the last couple of years there has been an increased focus on contaminated sediments in Norway. The main reason for this is that several fjords and harbours have consumption restrictions on fish and shellfish due to contamination. This also has an impact on the fishing industry which is the second largest industry in Norway next to the oil industry. In Norway the contaminated sediments are located in fjords and harbours. Dredging is often the preferred remediation technology to clean up the contaminated sediments. A contaminated sediment layer is often quite thin and additionally the seabed can be very irregular with water depths up to 100 m. These very difficult conditions for dredging has made it necessary to develop specialised dredging equipment. Two types of equipment for environmental dredging have been developed; one for water depths down to approximately 20 m and one for water depths down to approximately 60 m. Both types of equipment are environmental suction dredgers. The dredger which is used down to about 20 m water depth uses a fixed arm and the dredger for larger water depths uses a winch construction. Both types of dredgers are used at the clean-up of the Haakonsvern naval base outside Bergen in Norway.

This paper examines the overdredge tolerances associated with clamshell dredging in Puget Sound. The accuracy of the hydrographic survey, traditionally used to measure the overdredge allowance, is also reviewed. Methods of optimizing the overdredge allowance, given the inherent inaccuracies of the process, are discussed. Overdredge design and specification recommendations are made as well.

Reynolds Metals Company, under Administrative Order by the United States Environmental Protection Agency and the New York Department of Environmental Conservation, conducted the remediation of contaminated sediment in the St. Lawrence River associated with its Massena Plant operations. Mobilization for this effort started in Spring 2001 and dredging operations were completed by mid-October 2001. Chemicals of concern included polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), and dibenzofurans; with PCB concentrations ranging from below method-detection limits to greater than 2000 parts per million. Identified areas of contamination approximated 70,000 cubic yards of sediment along a half-mile stretch of the St. Lawrence River, with water depths ranging from 0 to 28 feet. Sediment was removed through use of a Cable Arm Environmental Clamshell bucket. The use of the Cable Arm buckets allowed for a level cut, and minimized turbidity/water collection. Each bucket was outfitted with depth sounders, pressure transducers and pressure switches that assisted in obtaining the location of the bucket in the water column, design depth determination, and removal verification. WinOPS dredge positioning software interfaced the bucket data with global positioning systems (located on both the crane boom tip and dredge barge), tide gauge, and bathymetric data in order to provide real-time monitoring and archival of these parameters in an electronic format.

Because the regional open-water disposal site for the Portland area was recently closed, the Port of Portland has had to change from in-water to upland disposal to manage sediments from its maintenance dredging operations. The Port of Portland designed and built a dredged material rehandling facility to receive dredge slurry that is hydraulically offloaded from a barge. The rehandling facility contains a primary basin for the initial hydraulic discharge and a secondary basin for quiescent settling and enhanced clarification of the dredging elutriate. The facility provides temporary storage and dewatering of the dredged material until a suitable beneficial use can be identified. Typically, the dredged material is suitable for use as fill at Port development sites. Existing regulatory guidance for in-water disposal was not applicable to upland disposition, so the Port worked with the dredged material management agencies to develop a tiered evaluation framework that was protective of both surface water and groundwater. Four pathways were evaluated by which contaminants could potentially be released to the environment: (1) releases to the water column at the point of dredging; (2) releases to the Columbia River through the effluent return flow at the rehandling facility; (3) releases to the river by way of seepage under the rehandling facility berm; and (4) releases to groundwater by infiltration beneath the facility. The proposed evaluation framework includes initial bulk sediment screening criteria, as well as more advanced laboratory analysis of dredging elutriate or leachate using Corps of Engineers (i.e., modified elutriate test, column settling test) or EPA (i.e., synthetic precipitation leaching procedure) protocols, as necessary. The results of this project support the use of a tiered evaluation framework for characterizing potential environmental impacts at an upland rehandling or disposal site. Field verification sampling of water column and dredge elutriate chemistry was also conducted; in particular, field sampling of effluent return flow from the rehandling facility validated the results of the modified elutriate test.

This paper discusses data collected by the author's firm over the past seven years and reported heretofore only in design reports published for sponsoring clients. Both laboratory and in-situ testing has been performed to characterize the physical, index, and strength properties of dredged material, soft marsh soils, and the sands and clays found beneath the natural marshes. In-situ testing has included the standard penetration test (SPT), the cone penetration test (CPT), and the field vane shear test. Typical geotechnical parameters for the various soils encountered in and around dredged material containment areas (DMCAs) are presented. While these typical parameters may be useful for preliminary design evaluations, any final design should be based on site-specific geotechnical characterization studies.

Dredged material characterization plays an important role in planning and design efforts for dredging operations. Geotechnical parameters are needed for input into dredging operation models and for evaluation of dredged material placement options. Proper selection of geotechnical parameters is crucial for accurate modeling forecasts and project design, yet often the required parameters are not available or readily obtainable. This paper discusses some of the issues related to geotechnical testing and evaluation of dredged materials with emphasis on innovative or expedient methods for determining geotechnical parameters.

This paper presents a comparison of two modeling approaches that can be used to predict the consolidation and desiccation behavior of dredged material, using a case study of Poplar Island, Chesapeake Bay. As part of the Site Development Plan (SDP) for Poplar Island, it is necessary to accurately predict the behavior of hydraulically placed dredged material soon after placement, as well as several years following placement. The accuracy of the prediction is critical because the success of the intertidal wetland portion of the site is highly sensitive to final elevations. This paper will present the results of comparative analyses using the U.S. Army Corps of Engineers' computer model PSDDF, and the University of Colorado computer model CONDES. In the PSDDF analyses, the desiccation was modeled simultaneously with the consolidation, but the settlement results are computed separately for each process. In the CONDES analyses the settlements from each component cannot be separated in a single run. Thus, in order to facilitate the comparison, CONDES analyses were performed initially for consolidation only and subsequently for consolidation and desiccation simultaneously.

This paper describes the process that the Port of Portland went through to manage its maintenance dredge material after its in-water disposal options were eliminated. That process included the search for new disposal options, an overview of the considered dredge material management concepts and the selected alternative. The paper also describes details of the design considerations and features for the selected alternative such as the Dredged Material Rehandling Facility (DMRF). The selected alternative consisted of a conventional clamshell dredging operation into barges that were later offloaded into the DMRF by a submersible agitator pump hung from a floating crane. The used agitator pump is capable of pumping high percentage solids and the fluidizing water jets that are attached to it are an effective way to help liquidize the dredged material. The paper specifically focuses on the barge unloading process that was selected, the equipment used for that process (including the 10-inch submersible agitator pump) and the engineering design of the operation. Experiences gained from the project are addressed with some interesting lessons learned about pump capabilities and performance, the dewatering phase of the dredged material, how environmental rules were applied, and the workability of the chosen concept. Some insights about the financial figures of the project available from the post-project review and evaluation are also included.

Dredging in semi-protected harbor areas is difficult for large cutter suction dredges, which cannot work under the action of waves. However, only this type of dredge can cut hard bottom materials. A case study was carried out in which net times of operation and productivities were defined for a large cutter suction dredge working in a semi-protected area, as a function of the monthly nearshore wave climate inside the harbor. A numerical model was utilized to predict wave conditions in the working area and dredge behavior under these waves was estimated. Possible scenarios of productivity for dredging hard bottom materials were obtained, and the best working season of the year was defined for different lengths of breakwater construction and levels of protection at the specific harbor site.

This paper deals in detail with different dredging techniques, with their applications and effects. Special attention will be given to the effects to the environment. We are able to avoid harmful effects for a great deal, by using certain measures. Measures have to be associated with costs and the question is, how can we weigh costs against profit for the environment and how much money are we willing to spend on the environment. In certain circumstances dredging is necessary, or at least better than doing nothing at all. In other areas you refrain from dredging; nature will "clean" the sediments by settling of new clean sediments during years to come.

Large volumes of dredged materials have to be removed each year from the waterways in the Netherlands, mainly for reasons of shipping and water discharge. Most of these dredged materials can be relocated in the sea or on land, but the more contaminated dredged materials (CDM) need to be disposed or treated. Until now treatment of CDM has only been done on a small scale, mainly because of the higher costs of treatment compared to disposal. The Dutch policy is aiming at enlarging the share of treatment of CDM into building materials in order to decrease the amount of waste that has to be disposed. The growing public resistance against new disposal sites has urged the Dutch government to take several initiatives. Firstly, a national inventory and assessment of the possibilities of large-scale treatment has been set up. Secondly several measures have been taken to stimulate the treatment of CDM.

The remediation of Oslo Harbor requires that approximately 780,000 m³ of contaminated sediments be dredged and subsequently disposed. Several disposal methods have been assessed; however, due to elevated concentrations of both organic contaminants and heavy metals as well as the high content of fines, sediment treatment to reduce the disposal volume has been ruled out. Capped disposal in an anoxic deep-water basin has been selected due to its potential for safe and economical long-term storage of dredged contaminated sediments. The disposal of dredged contaminated sediments under water requires that great care is taken to avoid both short term and long term release of contaminants. This paper presents the conceptual model utilized to investigate the environmental risk associated with possible contaminant transport mechanisms during and after disposal in an anoxic deep-water basin. Experimental results from the specific site assessment for Oslo Harbor are presented as well.

PCB is of environmental concern in Norway. Investigations and monitoring results have shown that more than 200 aquatic areas and land sites are PCB contaminated. From this results consumption bans has been given in 24 marine locations. PCB has never been industrial produced in Norway, but was imported from manufacturing countries since mid 1950. PCB was nationally banned in 1980. The source evaluations have been difficult due to diverse and diffuse input to the environment. Use of raw materials or PCB containing products has resulted in extensive accumulation in soils, sediments and biota. Risk-based approaches introduced in remediation during the 1990 initiated the apparent need for a working tool in PCB sources localization. Chemical concentration levels had so far been the tools for characterization and decision-making. Based on this a chemical fingerprint method was developed to distinguish different types of PCBs present, PCB manufactures and potential PCB containing products that had been used. The development was additionally triggered by the transition from total PCB quantification to congener specific analysis. Through an extensive literature study of internationally published analytical work of commercial PCB mixtures and product it was possible to define more than 20 standard PCB profiles. The standard profiles from different manufactures provide distinct fingerprint signals that can be recognized in soil and sediment samples. Unfortunate the method is so far not valid for higher tropic biotic levels, due to selective intake and accumulation. This paper explains the different steps in development of the standard PCB profiles and presents some guidance for the practical use in environmental studies. Selected case studies from the authors PCB database consisting more than 3000 data sets will be given.

An estimated 2.5 million cubic meters of contaminated sediments will need to be dredged from Los Angeles Region Harbors over the next five years. Currently there is a lack of a long-term strategy for management of contaminated sediments in the region and a lack of identified disposal alternatives making permitting of dredging projects with contaminated sediments difficult. A regional task force (Los Angeles Region Contaminated Sediment Task Force or CSTF) was formed in 1995 by the California legislature and tasked with developing a long-term management strategy for the disposal of contaminated dredged sediments. In support of this goal the U.S. Army Corps of Engineers is undertaking a Feasibility Study to develop a Regional Dredged Material Management Plan that will recommend a coordinated and managed approach to disposal of contaminated sediments.

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 multiuse disposal facilities and beneficial re-use, 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 how the CSTF identified and is evaluating the pilot and/or bench scale projects for the purposes of long-term dredge material management.

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 multiuse disposal facilities and beneficial re-use, and support efforts for watershed management to control contaminated sediments 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 CDSF executive members, the Los Angeles District Army Corps of Engineers. This paper presents the design and construction of the Aquatic Capping Pilot Project. The project involved the dredging of 100,000 cubic meters of contaminated Los Angeles River Estuary (LARE) material and placing the material in the North Energy Island Borrow Pit (NEIBP) — a historic borrow pit used to construct Island White. After the material was placed, 68,000 cubic meters of clean material was dredged from the South Energy Island Borrow Pit (SEIBP) and placed as cap over the LARE material. The material used for the cap was previously dredged from Queens Gate channel and was disposed in the SEIBP.

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.

The multi-agency Los Angeles Basin Contaminated Sediments Task Force (CSTF) was established in 1998 to develop a long-term management plan (Plan) by 2003 for dredging and disposal of contaminated sediments from coastal waters in Los Angeles County. The goal of the Plan is to identify environmentally preferable, practicable disposal alternatives, promote multiuse disposal facilities and beneficial reuse, and support watershed management efforts to control contaminants at their sources. To identify the most preferable sediment management alternatives, four pilot- and/or bench- scale studies were conducted by the Corps of Engineers Los Angeles District. This paper discusses the background, design, coordination, execution, and evaluation of the Cement-Based Stabilization Pilot Study. The Pilot Study consisted of a multitude of design, field and laboratory tasks including technology review, site selection, permits and approvals, bench study review, treatment process design, logistics design, sampling and testing program design, plans and specs, construction, sampling and testing, laboratory analysis and evaluation report. With extensive coordination with government agencies and environmental groups through the CSTF, the Pilot Study sets an example for implementing a challenging, sensitive project based on consensus among share holders.

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 re-use, 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 sediment washing, one of the four bench scale studies. A literature search and bench scale study were completed at the ERDC Waterways Experiment Station, to evaluate the feasibility of washing dredge material to remove chlorides and other salts prior to upland disposal and/or reuse. Current management practices in Southern California prohibit upland disposal of marine sediments because of concerns that salts will leach from the sediments and impair groundwater resources. The current study focuses on two approaches for sediment washing: passive-gravity washing and cake washing. While the primary objective is to evaluate salt removal, changes in bulk sediment and leachate chemical concentrations will also be evaluated.

The U.S. Environmental Protection Agency (EPA) Region 9 is investigating the feasibility of in-situ capping DDT and PCB contaminated sediments on the Palos Verdes (PV) shelf off the coast of Los Angeles, California. The U.S. Army Corps of Engineers (USACE) has recently completed a field pilot study of in-situ capping for Region 9 at this site. The pilot study involved placement of approximately 103,000 cubic meters (135,0000 cubic yards) of capping sediments in three 18 hectare (45 acre) capping cells situated at water depths between 40 and 70 meters. Cap material was placed by hopper dredge using conventional and spreading placement methods. An extensive environmental monitoring program was conducted in stages before, during and after cap placement using state-of-the-art equipment and techniques. Modeling was also conducted during the placements to guide field operations and following placements to improve future predictive capabilities. This paper provides a description of the project setting and conditions, the rationale for capping options and the capping pilot, and a summary of how the study results may be applied to any future scale capping operations on the Shelf.

The U.S. Army Corps of Engineers designed and managed a field pilot study of in-situ capping of contaminated sediments on the Palos Verdes Shelf off the coast of Los Angeles, California in August-September 2000. The extensive monitoring program was conducted before, during, and after cap placement using state-of-the-art equipment and sampling techniques. This paper provides an overview of the following elements of the monitoring program: 1) hopper dredge operational monitoring during all cap placement events, and 2) monitoring of near-bottom currents and turbidity in close proximity to the dredge during selected cap placement events. The combination of these monitoring techniques provided a unique opportunity to assess cap placement operations and their short-term impact on near-bottom currents and turbidity in close proximity to the placement site.

Particle trajectories along a cutter blade have been determined for several rotational velocities of the cutter head and a constant suction flow. The initial positions of the particles were varied in the simulations as were their initial velocity. Simulation results seem contradictory to the test results at first notice. The lower the rotational velocities, the more the particles seem to move towards the suction mouth. Examining the flow fields determined by a CFD model showed that the water velocities were relatively low resulting in a large difference in velocity between the blade and the water. Furthermore, the pumping effect of the cutter head could have been underestimated in the CFD model. A thorough validation of this model is needed. The simulation model for the particle trajectories should be extended by implementing the trajectories of particles in the free flow.

The development of new techniques in the dredging industry has made possible the hydraulic transport of slurries in pipelines at increasingly higher solids concentration. The modern trailing suction hopper dredges are capable of pumping sand-water slurries at densities higher than 1600 kg/m³. The high concentration of solids influences the economy of the transportation, since it changes the operational characteristics of centrifugal pumps and pipelines. However, little is known about the effect of high solids concentration on the operation of a pump and a pipeline. Laboratory experiment designed to provide information that would lead to greater understanding of the mechanisms governing the pipeline flow of settling slurries were conducted in a 150-mm pipeline of the Laboratory of Dredging Technology of the Delft University of Technology. The investigations revealed the effect of particle size and slurry density on the friction process in a pipeline transporting sand-water slurries. The paper analyses the effect of concentration and size of transported solid particles on the economy of the transportation of slurries by relating the specific energy consumption — the parameter that evaluates the efficiency of a slurry pipeline - to the flow parameters (velocity, concentration and solids throughput) in the pipeline. The laboratory findings are compared with the field observations in two large slurry pipelines (650 mm and 700 mm). The observations indicate that it is beneficial to transport fine to medium sands in highly concentrated slurries. To ensure safe and economic operation the sand-water slurry in a horizontal pipeline should be transported at velocities for which the granular bed sliding over a pipeline wall starts to disintegrate and dissolve. At these velocities the specific energy consumption is minimum.

In the last decennia extensive research has been carried out into the cutting of water saturated sand. In the cutting of water-saturated sand, the phenomenon of dilatation plays an important role. In fact the effects of gravity, inertia, cohesion and adhesion can be neglected at cutting speeds in the range of 0.5 – 10 m/s. In the cutting equations, as published by Miedema, there is a division by the sine of the sum of the blade angle, the shear angle, the angle of internal friction and the soil/interface friction angle. When the sum of these angle approaches 180°, a division by zero is the result, resulting in infinite cutting forces. There are 3 possible conditions that can be used: the principle of minimum energy, the circle of Mohr, and the equilibrium of moments of the wedge. These methods are discussed and the choice made is explained.

In an increasing number of dredging contracts, environmental requirements concerning sediment plumes have to be met. The required frequency of measurements to check if the actual turbidity or concentration of suspended solids complies with the limits, varies largely per contract. When measurements are taken continuously the probability that the limits are exceeded without registration by measuring are small, but continuous measurement methods are very expensive. The objective of this study is to optimise the number of measurements at a location, i.e. the number of ship crossings through a sediment plume, given the costs and the accuracy of the turbidity measurements, by a statistical data analysis. Data from the O/resund Fixed Link project in the Baltic Sea is used for the case study. Turbidity was measured 24 hr/day throughout this project. The measurements of one day, 15 January 1996, were used for the data analysis. The measurements were carried out from a vessel that sailed perpendicular across the sediment plume, at a distance of 200m from the dredger, collecting current and turbidity data. Upstream turbidity was measured for baseline values.

Maintenance dredging of fine-grained sediment that accumulates in the shipping channels in the Upper Chesapeake Bay is an ongoing process necessary to ensure navigational access to the Port of Baltimore. Nine designated open-water disposal sites adjacent to the Chesapeake and Delaware Canal approach channel have been utilized since the 1960s for maintenance dredging, providing for low cost placement alternative to other options. Most of the designated open-water sites have either filled to capacity or have been discontinued due to environmental concerns. In 2001, an agreement was reached between the State of Maryland and environmental advocacy groups to end open-water disposal in 2010 and place all future dredged sediments in confined sites or utilize for beneficial purposes. It is essential that the remaining capacity of available open-water sites be maximized in an environmentally acceptable manner to provide adequate time for the development of beneficial use options or confined placement sites.

An initiation of sediment transport model (ISTM) is described for predicting the initiation of dredged material transport by ocean currents at Ocean Dredged Material Disposal Sites (ODMDS), and it is applied to two ODMDS sites offshore of Texas and Louisiana coasts where previously measured nearby bottom current data are available. The model incorporates the hydrodynamics of current boundary layer flow, fluid-sediment interaction near the bottom, and sediment transport mechanics. The fundamental approach to predicting sediment transport is to relate the friction factor and bed shear stress to the sediment transport rate. The approach is based on comparing the calculated bottom shear stress created by an ocean current to the critical shear velocity for sediment movement. Two model limitations are that the hydrodynamic environment is limited to near-bottom unidirectional steady current and the sediment is cohesionless. The model predicts the critical bottom current speed that is expected to initiate sediment movement based on the Shields parameter for a particular grain size. The model is further used to estimate the current velocity at a depth where existing current meter data are available. Near bottom current meter data collected and processed during the period 1982 through 1984 in the vicinity ODMDS sites of the Freeport ship channel and the Calcasieu ship channel are used to demonstrate the application of the ISTM model. The results indicate the percent time for each month of the year when the bottom currents are sufficient to move the sediment. The current direction is divided into eight quadrants and is used to show the direction of sediment movement toward or away from the Freeport and Calcasieu ship channels. The model can be used to assist in the timing of the dredging operations and indicating the percentage of time when the ocean currents could possibly redeposit the dredged material back into the ship channels. The results show that during the dredging season the currents were shown to be away from the Freeport and Calcasieu ship channels.

To be protective of living marine resources the ocean disposal of dredged materials must be managed such that these activities do not significantly disrupt the natural environment upon which marine animal and plant communities depend. Two important controlling factors affecting the diversity, abundance and general health of hermatypic (stony) corals comprising reef communities in tropical and subtropical environments are sedimentation and the availability of sunlight for photosynthesis. Disposal activities result in residual sediment plumes which, when occurring near coral communities, can expose corals to increased suspended sediment levels and sedimentation rates and reduced light intensity. In order to avoid adverse impacts to corals, dredged material disposal guidelines should ensure that disposal activities do not add significantly to sedimentation and light attenuation caused by naturally occurring oceanographic and meteorological processes. The development of disposal guidelines requires an understanding of these processes and their influence on sedimentation and light availability. Studies of these processes are currently underway at the Miami, Florida Ocean Dredged material Disposal Site (ODMDS). Initial results of eight months of acoustical backscatter data collected from October 1998 to October 1999 suggest a marked seasonal difference in average natural background suspended sediment concentrations at reef locations inshore of the ODMDS. Fall seasonal averages were higher due in part to several hurricanes and tropical storms that caused high elevations of suspended sediments on reef communities for two to four day periods. Suspended sediment guidelines for dredged material disposal will depend on the importance of these major oceanographic and meteorological events as determining factors for coral reef structure and function.

The Port of Portland required an independent technical opinion on sedimentation at the Port's Berth 501, Terminal 5, Willamette River. Terminal 5 is located on the east bank of the Willamette River, approximately 0.8 kilometers (half a mile) upstream from its confluence with the Columbia River. This confluence with the Columbia is located approximately 160 kilometers (100 miles) from the Pacific Ocean. At issue was whether riverbank erosion was contributing to sedimentation in the terminal's ship and barge berths, or whether the maintenance dredging was contributing to riverbank erosion. The Port selected GRI, a Pacific Northwest geotechnical firm, and Parsons Brinckerhoff Ports & Marine Group to evaluate the situation using historic data, limited site investigation, and the key investigators' experience. The scope of work included a site examination, limited sediment sampling and grain size analysis, review of existing information, engineering studies, and preparation of a report.

In 1995, three quarters of a million cubic yards of material was dredged from Fort Pierce Harbor (Florida) and disposed in the Fort Pierce, Florida Ocean Dredged Material Disposal Site (ODMDS). By 1996, reports of thick mud deposits (muck) discovered on shelf hard-bottom resources raised concerns of potential adverse impacts of offshore dredged material disposal. Sediment samples were collected from hard-bottom muck deposits, the Fort Pierce ODMDS, harbor, and shelf off of St. Lucie County, Florida. Fifteen trace elements and three naturally occurring radioelements were analyzed in the silt and clay (fine) particle size fraction. Numerical classification (clustering) analysis and multidimensional scaling (ordination) of the trace element and radiometric data failed to show any strong degree of similarity between hard-bottom muck and fine sediments collected from the ODMDS or harbor locations. Hard-bottom muck tended to form unique clusters and groupings in ordination space. These data show that hard-bottom muck was unique in elemental composition and their dissimilarity to sediments taken from the dredged material disposal site and the harbor locations suggest that the muck was comprised mainly of non-dredged sediments of indeterminate origin.

The latest "State of the Art" on Dredge Track Presentation System (DTPS) Due the high demand for an optimal presentation of the working position of dredges on the hydrographic chart, a new innovative hydrographic multi language (*) Dredge Track Presentation System is developed. This DTPS package (Windows NT/C++) is especially developed for Hopper- Cutter- Excavator- Clamshell- and Bucket line dredges. The DTPS System enables amongst others the dredge operator to see on-line, with the highest possible accuracy, the dredging tool (cutter wheel, dredge head, clamshell, bucket, etc) in the profile and the actual updates from the dredge on the bathymetric electronic chart in absolute position.

Major progress in enhancing port operating efficiency, for example in the container shipping industry, has been made in recent years in respect of vessels and "landside" handling refinements. This presentation complements these developments and relates to optimising "waterside" performance of blind-ending basins. Basins may be created by either building breakwaters seawards from a straight coast or by digging into alluvial deposits along channel margins. They provide safe-harbouring from the most severe wave and water current stresses, ice loading, etc., and are consequently a commonly-resorted-to feature all round the world. However, the entrances to blind-ending basins in silt-laden waters are the site of a "conflict of interests". In order to provide free and safe access, these entrances must be wide. In contrast, the wider the entrance the greater is the opportunity for sediment to be input and deposited. Even in low turbidity systems, such harbour basins often have a high siltation rate. Intrinsic characteristics of flow and water/sediment exchange lead to a high fraction of input material being deposited in the basin entrance, where it can rapidly form a shoal and an impediment to navigation. In basins adjacent to industrialised areas, the sediment deposited is often the finest grained and most severely contaminated. It is consequently expensive to dredge, treat and dispose of such material.

Sediment deposition into receiving waterbodies has long been a problem for maintaining ports and shipping channels. Ocean disposal of dredged material, once the prevalent disposal method globally, is becoming more restricted due to the range of contaminant concentrations in the dredged material. In the New York New Jersey (NYNJ) Harbor, the volume of potentially contaminated dredged material not suitable for ocean disposal will have to go upland. Due to maintenance dredging and harbor deepening, the volume of this material is expected to exceed 100 million cubic yards over the next forty years. Upland disposal of dredged material is expensive and has limited capacity. Innovative solutions are required to find adequate disposal options, targeting beneficial uses of dredged material. To make beneficial use viable, we need to improve efficiency by reducing costs, reduce environmental impacts and create marketable products. Key barriers to the beneficial use of these materials include intermittent supply, and lack of demand for recycled dredged material, regulatory and public acceptance, and capital costs. We propose, citing NYNJ Harbor case studies, a range of potential solutions to address long-term and short-term concerns, including changes in legislation, business, technology, science and education.

The purpose of this paper is to identify the regulatory programs and requirements applicable for dredged material to be beneficially reused in an upland environment. This paper will describe the transition of the material from an in-water regulatory program to an upland regulatory program; to properly and beneficially manage the dredged material. Beneficial use of dredged material is an integral part of the dredge material management process. Clean dredged material can be used for construction fill, topsoil, wetland mitigation projects. Slightly to moderately contaminated material may be acceptable for upland fill beneath a parking lot, for creation of a soil berm around a dredge material dewatering facility, or daily cover at a landfill.

Dredged material from metropolitan areas may be contaminated above State cleanup criteria for either residential or nonresidential uses. This presents a challenge to agencies charged with land based beneficial use of dredged sediments. To propose use of such sediments on uncontaminated property presents difficult public acceptance and regulatory issues. On the other hand, use of contaminated dredged material on sites already contaminated by prior industrial activity can provide a more logical regulatory and policy "fit" to solve an otherwise contentious siting issue.

In a setting where military mission and environmental stewardship are often viewed as competing interests, the Navy is working towards achieving a balance in San Diego Bay. The Navy has had a long history of activity in San Diego dating back to 1846, and today has established a major presence in the San Diego Bay area. Currently, there are nine naval facilities adjacent to San Diego Bay. All of these are using, or have used, the waters of the bay in their daily operations, necessitating a wide range of dredging and disposal actions to support military mission requirements. The San Diego Bay is a unique ecosystem of threatened and endangered species, special aquatic sites, and essential fish habitat. It is a setting of military, recreational, and commercial uses whose management draws environmental and political attention.

The Pacific Salmon is the defining symbol of the Pacific Northwest. Factors affecting its continued survival set the stage for the conflict and cooperation of diverse individuals, interest groups, state agencies, and federal agencies. Various dredging activities have been identified as having a potential negative impact to listed endangered salmonids in the Columbia River. The interrelationship of culture, politics, and science are discussed in relationship to resolving divergent view-points and removing uncertainties to the proposal to deepen the Columbia River Federal Navigation Channel from 40-ft to 43-ft.

The U.S. Army Corps of Engineers (USACE) is in the final stages of updating and merging three of its previous dredging Engineer Manuals (EMs) into a single document entitled Dredging and Dredged Material Placement, EM 1110-2-5025. This new EM consists of the updated versions of three previous EMs, Dredging & Dredged Material Disposal (EM 1110-2-5025, 1983), Beneficial Uses of Dredged Material (EM 1110-2-5026, 1987), and Confined Disposal of Dredged Material (EM 1110-2-5027, 1987). In addition to updating the old EMs, this document also includes a new section on open-water placement. The terms disposal and placement are used synonymously to describe the dredged material deposition after its removal from the dredge cut. This paper provides an overview of this comprehensive document that describes the dredging equipment and placement techniques used by the USACE in navigation projects, and provides management, engineering, and design guidance for activities associated with new work and maintenance projects. Guidance is provided on: 1) the evaluation and selection of dredging equipment, 2) planning, designing, constructing, operating, and managing open-water and confined dredged material placement areas to provide adequate storage volume for both short-term and long-term placement needs, and 3) planning, designing, developing, and managing dredged material for beneficial uses, incorporating ecological concepts and engineering designs with biological, economical, and social feasibility.

The Corps of Engineers Silent Inspector (SI) dredge monitoring system measures dredge performance and position in real-time. The SI has on-board analysis capability that computes the pumping, sailing, and dumping times along with the hopper load in Tons Dry Solids (TDS). TDS has been incorporated into the economic load solution as the load metric rather than in-situ sediment volume. An economic load analysis module for the SI has been developed and tested against previously recorded SI data from dredges operating in the Southwest Pass of the Mississippi river entrance. Preliminary results of the data analysis indicate that for cuts close to the disposal area, total load cycle times could be reduced by 30% with less than 10% reduction in load per cycle. Details of the LP solution are presented along with an analysis of the effects of errors in TDS measurements. Tests of the system on operational dredges in Southwest Pass are planned for this year.

This paper examines the importance of properly characterizing the dredging target areas as a prerequisite for design and implementation of environmental dredging projects. Target areas at projects completed to-date have frequently been inadequately characterized, leading to the selection of improper dredging equipment and procedures and resulting in project delays, cost overruns, and unsatisfactory outcomes.

Before developing a sediment removal program, collection of appropriate site data is a crucial step. Sediment characterization efforts were performed to estimate volume and chemically characterize the sediment and adjacent bank soils for disposal. These activities were performed in Ruck Pond, an urban, impounded pond that had polychlorinated biphenyls (PCBs) in the sediment. The sediment was initially probed to measure depths which were used to estimate the in-situ sediment volume. Characterization for disposal included two phases of sampling to distinguish sediment with greater and less than 50 parts per million (ppm) PCBs using the nearest-neighbor approach. Representative sediment were subjected to the Toxicity Characteristics Leaching Procedure (TCLP) and sampled for reactive sulfide, total cyanide, and chlorine, to facilitate landfill disposal. Bulk sediment samples were collected for treatability testing to identify the most cost-effective stabilization agent and dosage that was needed to reduce the sediment water content to acceptable levels for transport and disposal. Bank soils were sampled in a phased manner to determine the extent of affected soil. Geotechnical properties of the sediment were determined and PCB field test kit results were compared with laboratory data to evaluate whether the kits would be useful during removal. Outfalls into the Pond were evaluated as potential PCB sources and soil borings were made to estimate infiltration rates.

A rapid and sensitive cell-based screening assay for dioxin equivalences (TCDD EQs) in dredged sediments has been developed. The P450RGS assay employs a transgenic human hepatoma cell line in which the firefly luciferase gene, luc, has been stably inserted as a reporter. P450RGS conforms to APHA Standard Method 8070 and ASTM Standard E-1853. EPA has promulgated the assay as EPA Method 4425 in update IVA of the EPA SW846 Methods Manual. Modifications to the method made at USACE ERDC-WES include a combined extraction/cleanup procedure using accelerated solvent extraction (ASE) with a sulfuric acid/silica gel packing in the extraction cell, and a 96-well microtiter plate format for the assay. These modifications substantially increase the volume of sample throughput and reduce the cost of the assay. Assays in which TCDD EQs are reported are typically less than 1/10^th the cost of dioxin analysis using GC/MS, and have comparable sensitivity.

The purpose of this work was to document testing and analysis of upland disposal of dredged material potentially impacted with dichlorodiphenyl-trichloroethane (DDT) from the Little Sunflower River, Mississippi. Bench-scale efforts were directed towards the investigation of the availability, toxicity, sequestration, and stabilization of DDT in the Little Sunflower River sediments. This entailed modeling and experiments designed to determine the phase partitioning of DDT and its release to the aqueous phase. This work emphasized the study of aged contaminant mixtures in sediment cores for which the sequestration of DDT often renders such unavailable. Reporter gene probes for specific catabolic genes and defined microbial community approaches allowed structured studies to assess DDT degradation, desorption, and stabilization.

This paper presents Part 1 of a two-part case-study on the Cascade Pole site (site) sediment remediation. This part of the case study presents the site background and history, the chemicals of concern and related sources, the regulatory process, the site environmental investigations, the Sediments Operable Unit (SOU) cleanup action plan (CAP), and the construction permitting process. Part 2, a separate paper in these proceedings, addresses remedial design and construction.

This paper presents an overview of the key elements of the CPC sediment remediation project and highlights the associated design constraints and construction methods used to carry out the work. Part 1, a companion to this paper (included in these proceedings), presents the site history and development of the cleanup goals and remedial strategy.

A large environmental dredging project was completed on the St. Lawrence River near Massena, New York between April and December 2001. The project entailed the dredging of PCB-contaminated sediments from an area of 12 hectares (30 acres), in water depths up to 8.2 m (27 ft), adjacent to the main shipping channel for the St. Lawrence Seaway. A 1,160 m (3,800 ft) long sheet pile wall was installed to isolate the remediation area from the river. Inside the sheet pile wall, a 366 m (1,200 ft) long silt curtain was erected to isolate the more highly contaminated areas. Air gates were used to allow for barge access into the area enclosed by the silt curtain and reduce the circulation of turbid waters within the enclosure.

An environmental dredging project was completed on the St. Lawrence River near Massena, New York between April and December 2001. The project entailed the dredging of PCB-contaminated sediments from an area of 12 hectares, in water depths up to 8.2 m, adjacent to the main shipping channel for the St. Lawrence Seaway. The area was divided into a total of 268 dredge cells, each with a target depth of excavation. Sediment verification samples were collected after each dredge pass. PCB results from these samples determined whether the cells had been remediated or required additional dredging to meet the cleanup goal of 1 ppm PCBs. A key issue during the design involved the development of decision criteria for determining how much additional dredging to do when the cleanup goals were not attained after the second dredge pass. The primary objective was to retain control over the dredging process by defining the requirements for each cell prior to the start of dredging, establishing the exact conditions when redredging was required as well as those situations where any further redredging was at the discretion of the project team (e.g., to avoid capping). This approach sought to avoid potential delays waiting on field decisions by oversight personnel as to whether additional dredging was needed.

In the spring of 2001, an ambitious dredging project was kicked off in Massena, New York. The objective: remove an estimated 77,000 yd³ of PCB-contaminated sediment from the St. Lawrence River opposite the former Reynolds Metals Company St. Lawrence Reduction Plant. A 3800-ft long sheet pile wall to isolate the remediation area from the river was installed, within which contaminated sediment were dredged using specialized clamshell buckets and hauled ashore for dewatering, processing and disposal. The project was exquisitely detailed and diagramed, from the expected percentage of analytical variability in sediment PCB analyses down to the timing, in minute and seconds, of each bucket cycle, for the work had to be accomplished in one season—the sheet pile wall had to be pulled and equipment demobilized before the river froze. A number of complications ensued, both onshore and on the water, requiring frequent departures from the expected flow of work and schedule. In the end, work was being driven as much by the Contingency Plan as it was by the Final Design and Work Plan. Many lessons were learned, which fall into several broad categories, including equipment and labor; pre-dredging bottom conditions and extent of contamination; and regulatory oversight.

The St. Lawrence River Remediation Project entailed the removal of approximately 65,500 m³ (85,600 yd³) of PCB-contaminated sediment from near-shore areas along an approximate 1.2 km (0.75-mile) long reach of the river. The initial budget for the project, prepared at the time the 1998 Record of Decision (ROD) was signed, was $63 million. Cost estimates developed during the design phase were based on completing the entire project in a single construction season (April–November). The final construction estimate, completed just prior to mobilization, was $41 million. Through 2001, actual costs were slightly under the pre-mobilization estimate; however, an abbreviated second construction season (2002) will be needed to complete underwater capping in a small area (0.44-hectare). Although the project encountered significant complications and unexpected conditions throughout the remediation work, the final breakdown of costs does not vary significantly from the pre-mobilization budget estimate. Cost overruns during the 2001 construction season were observed in a number of areas, namely the construction of onshore sediment storage and handling areas, environmental monitoring, sediment processing, demobilization, and construction management. Cost overruns were attributed to a number of factors, including problems in obtaining the required cleanup goals for sediment, which prolonged the overall project and led to considerably more dredging activities; unexpected complications regarding sediment handling and processing; and the need to greatly expand the scope of environmental monitoring activities in response to regulatory and stakeholder concerns.

The St. Lawrence River (SLR) Sediment Removal Project was part of an ongoing site-wide CERCLA remediation program addressing polychlorinated biphenyl (PCB)-impacted sediments and soil at General Motor's (GM's) 270-acre manufacturing facility property and adjacent off-site areas located in Massena, New York. The Record of Decision (ROD) issued for this site specified a sediment PCB target cleanup goal of 1.0 part per million (ppm), to the extent technically practicable. The sediment removal was conducted in accordance with the ROD and a Unilateral Administrative Order (UAO) issued by the United States Environmental Protection Agency (USEPA). In order to meet the project's cleanup goal, approximately 18,000 cubic yards (cy) of sediment rock and debris were removed via hydraulic and mechanical dredging during the summer and fall of 1995, and a sediment cap was designed and installed to address an area where final PCB levels in the sediment remained above 10 ppm, even after excessive attempts. Annual monitoring and maintenance activities are currently being performed at the site to ensure the integrity of the sediment cap. The sediment removal portion of this program was completed with the effective cooperation and teamwork of GM, USEPA Region 2, the New York Department of Environmental Conservation (NYSDEC), the St. Regis Mohawk Tribe (SRMT), Environment Canada, Blasland, Bouck & Lee, Inc. (BBL), and Sevenson Environmental Services. This paper provides a comprehensive overview of many aspects of this extensive river-dredging project, including studies, project scoping, contracting, sediment removal, and environmental monitoring.

Maintenance and capital dredging is absolutely necessary to keep shipping lanes open and harbors accessible. Since the early 1970s the ecological impact of dredging processes and disposal techniques has been studied carefully. Facing strict environmental regulations, ports worldwide are currently changing their dredged material management plans to stay economically viable. Restrictions and exclusion of traditional disposal techniques require a multifaceted approach to dispose of, recycle, decontaminate and reuse the material. For clean dredged material several strategies of beneficial use have been established successfully throughout the last decades. However, contaminated sediments are more difficult to place. Especially the productive use of the soft clay / silt fraction poses many unsolved problems because it tends to attract the pollutants. Existing technologies are often energy-consuming and expensive, treat only certain fractions of dredged material, raise issues of secondary pollution, or lack community acceptance.

In order to investigate the potential uses of treated dredged sediment as fill material in transportation related projects, a comprehensive series of laboratory tests was conducted on dredged sediments from the Hudson River. The dredged sediments were mixed with Type I Portland Cement (9%, 11%, and 13% by wet weight) at three different water contents (90%, 130%, and 170%). The tests conducted on these cement treated sediments were index properties, compaction characteristics, unconfined compressive strength, consolidation tests, consolidated-undrained triaxial tests and x-ray diffraction analyses. Following cement treatment, tests have indicated that the material becomes inorganic low plasticity silt (MH) whereas the untreated sediment is classified as organic clay/silt of medium to high plasticity (OH). Compaction characteristics tests indicate that the samples have a relatively flat-shaped curve, with an optimum water content of approximately 40%, which is significantly lower than the field values. The unconfined compression tests suggest that 90% water content and 11% cement content are optimal for strength development (482.6 kPa (70.0 psi) at 28 days and 246.8 kPa (35.8 psi) at 7 days). The data suggests that remolding has a significant adverse effect on strength development. The consolidation tests show that the reduction in void ratio decreased with increasing cement content and decreasing water content and the compressibility of the samples changed in the same way. Hydraulic conductivity increased with increased levels of cement treatment. Based on consolidated-undrained triaxial testing the effective friction angle for the treated sediments ranged from 43° to 44.9° and the cohesion intercepts ranged from 0.1 to 0.5 MPa (0.8 to 5.3 psi). Overall based on the present study, it can be concluded that the cement treated dredged material can be used in a cost-effective way as non-structural or embankment fill. The findings of this study are being compared to recent studies of similar type to evaluate the results.

The presence of contaminated sediments in our urban harbors is emerging as a serious environmental and economic concern. New York/New Jersey Harbor is both the oldest port in the United States and the largest port complex on the east coast of North America. To ensure that the Port of New York/New Jersey remains a viable port, environmental restoration and channel deepening projects yielding approximately 9 million cubic meters (12 million cubic yards) of dredged material over the next five years are required. Environmental regulations enacted over the past few decades restricting placement of dredged material in open waters have led to an increased interest in beneficial use applications and sediment decontamination technologies. Under the reenacted Water Resources Development Act of 1996, funding has been appropriated to support these objectives that seek alternatives to ocean disposal. Locally in New Jersey, two public-private partnerships have been established to demonstrate the technical and economic feasibility of developing regional sediment processing and decontamination facilities, respectively.

This paper presents current practices and experience with closed buckets nationwide, discusses the feasibility of using a closed bucket for remedial dredging, and presents the results of using a closed bucket during Stage 1 of the East Waterway Deepening Project. Information on case histories nationwide for remedial dredging using a closed bucket will also be presented in this paper. The East Waterway is located at the mouth of the Duwamish River to the east of Harbor Island, Seattle, Washington. During permitting for Stage 1, local agencies expressed concern over the effect that resuspended unsuitable sediments from dredging operations may have on water quality in the East Waterway and points downstream. A closed bucket is a technology that was developed to help reduce sediment resuspension and sediment loss; the agencies requested that the Corps and the Port investigate using a closed bucket to dredge the East Waterway. Conclusions from the feasibility study prepared for the Corps and Port, and discussion of Stage 1 field operations and results will be presented.

The process of extracting bottom sediments contaminated with metals and organic chemicals will result in significant losses to the adjoining media. A multimedia box model has been developed for environmental dredging in order to quantify and forecast the various losses. Prior to model development detailed mass balance studies quantifying the effectiveness of dredging and the collateral losses were completed at four sites. The sites were: Bayou Bonfouca, LA containing PAHs, Grasse River, NY containing PCBs, Manistique Harbor, MI and the Fox River, MI. At the latter two sites PCBs were the major concern. The objective of performing detailed studies at a limited number of sites that have been dredged was to gain specific knowledge about the various aspects of the dredging operations in order to develop quantitative chemodynamic process elements for each. The material presented will include brief descriptions of the Fox River site, the dredging technologies used, the monitoring results used for extraction efficiencies of the in-place mud and chemical masses, and the quantities lost by various chemodynamic processes. The development and structural elements of the multimedia model designed to estimate mud and chemical mass quantities extracted and the collateral losses to the surrounding environmental media will be reviewed. Data collected at the Fox River site was used to quantify both the solids and chemical mass balances. Comparison of the model predicted mass quantities and the reported field measured one of extracted and loss material will be made. The model predictions and reported quantities were in general agreement. For the PCBs in Deposit N the model and reported values were: 69% & 82% delivered to shore, 28% & 14% non-targeted, 3% & 4% advection down stream, 0.002% evaporated and 0.006% & 0.02% fall-back.

Sand is being dredged from the seabed in Hong Kong by large trailer suction hopper dredgers to provide fill material for land reclamation. The major environmental concern is the dispersion and deposition of fine sediment in the overflow plume and the resulting potential impacts on the nearby capture and culture fisheries resources, coral assemblages, bathing beaches, and water intakes. In addition to the comprehensive Environmental Monitoring and Audit program designed to safeguard sensitive receivers, a series of sediment profile imaging surveys were performed in early 2001 to verify sediment settlement predictions made at the time of the environmental impact assessment using computer hydraulic modeling techniques. The survey results revealed that the rate of deposition and thickness of deposits are broadly similar to predictions from the hydraulic modeling, but the extent of deposition is different than predicted. The sediment profile imaging also indicates that in most locations, recolonization of the settled material by benthic fauna has managed to keep pace with the deposition.

Water quality monitoring programs for the water runoff at unconfined dredged material disposal sites in Glynn/McIntyre County, Georgia, were conducted during hydraulic dredging disposal operations for the Atlantic Intracoastal Waterway (AIWW) maintenance dredging performed in 1999 and 2001. The monitoring was performed on the water runoff into the adjacent water body at locations from disposal areas along the AIWW. The dredged material was a fine-grained clayey silt and silty clay in general. Field measurements included water temperature, dissolved oxygen (DO), pH, conductivity, salinity, and turbidity along with a brief description of weather, water, and tide conditions. Water samples were collected from several locations and tested in the laboratory for total suspended solids (TSS). TSS concentrations for the remaining locations were estimated through a correlation established by statistical regression analysis between field turbidity measurements and TSS laboratory analytical results.

Proposed placement of dredged material in a deep trough of the Potomac River below Alexandria, Virginia led to environmental concerns that the deposited material would disperse to nearby shallow bottom habitats. Between December 15, 1999 and February 5, 2000, approximately 328,000 cubic yards of dredged material, representing 212 split-hull barge loads, were placed in the trough. Monitoring efforts included pre-, during, and post-disposal deployment of bottom-mounted optical backscatter sensors (OBS), and two sediment profiling imagery (SPI) surveys, one four months following placement and a second a year later. Examination of the OBS data indicated that pulses of extremely turbid (>1,000 NTU) water moved through the study area prior to the onset of disposal operations, and intermittently throughout the study period. Bottom waters in the channel thalweg were generally much more turbid than bottom waters over adjacent shoals. These high background turbidities tended to mask any elevated turbidities linked to the disposal events. The few turbidity pulses that were discerned to be associated with disposal events were relatively small (< 250 NTU) and ephemeral (< 1 hr). SPI images collected four months after cessation of disposal and a year later revealed "signatures" of sandy dredged material within the trough. No evidence of significant dispersion of dredged material outside of the trough was seen. Following cessation of disposal, benthic assemblages in the vicinity of the site appeared to be undisturbed. Although long-term data describing bathymetric changes within the trough are needed to evaluate the stability of the deposited material, no significant long-term (1.5 year) movement of materials out of the trough was observed.