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    Development and testing of the Sediment Distribution Pipe (SDP) : a pragmatic tool for wetland nourishment
    (Engineer Research and Development Center (U.S.), 2024-04) Welp, Timothy L.; Harris, Brian D.; McFall, Brian C.; Tyler, Zachary J.; Beardsley, Colton T.; Eckstein, Adrienne M.; Perkey, David W.; Henderson, Matthew R.; Freddo, Alexander J.; Smith, Hayden J.; Mohan, Ram K.; Coastal and Hydraulics Laboratory (U.S.); United States Air Force Academy; Anchor QEA (Firm)
    Standard dredging operations during thin layer placement (TLP) projects are labor intensive as crews are necessary to periodically move the outfall location, which can have lasting adverse effects on the marsh surface. In an effort to increase efficiency during TLP, a novel Sediment Distribution Pipe (SDP) system was investigated. This system offers multiple discharge points along the pipeline to increase the sediment distribution while reducing pipeline movements. An SDP Modeling Application (SDPMA) was developed to assist in the design of SDP field applications by quickly assessing the pressure and velocity inside the discharge pipe and approximating the slurry throw distances. An SDP field proof of concept was performed during a two-phase TLP on Sturgeon Island, New Jersey, in 2020. The SDPMA was shown to be an accurate method of predicting performance of the SDP. The SDP was successful at distributing dredge material across the placement site; however, further research is warranted to better quantify performance metrics.
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    Pilot project using tickler chains in lieu of deflectors at Fire Island Inlet to Moriches Inlet, New York, borrow sites
    (Engineer Research and Development Center (U.S.), 2024-03) Welp, Timothy L.; Balazik, Matthew T.; Emery, Benjamin E.; Dickerson, Dena D.; Bates, Phillip C.; Coastal and Hydraulics Laboratory (U.S.); Environmental Laboratory (U.S.); United States. Army. Corps of Engineers. Jacksonville District; Dredging Operations and Environmental Research Program (U.S.)
    Risk for incidental take of sea turtles and sturgeon exists during hopper dredging operations throughout turtle and sturgeon habitats. Since 1992, draghead deflectors have been the main engineering tool used to minimize incidental hopper dredging takes of sea turtles and are also thought to reduce the chance of sturgeon impingement or entrainment. Although reduced, turtle takes still happen annually, and the draghead deflectors reduce dredging productivity, increase fuel usage, and increase costs of operations. As such, there remains a need to research alternative turtle avoidance measures. The non-US dredging industry has used various versions of an engineering control called tickler chains (TC) in lieu of deflectors. If effective, TC could lower dredging costs and increase production in comparison to deflectors. This technical report describes a pilot study where TC were used in lieu of deflectors at Fire Island Inlet, New Y0rk. To the authors’ knowledge, this is the first time since the early 1990s that hopper-dredging has occurred without draghead deflectors along the east coast. No takes were recorded during the pilot study; however, no research was done to determine if sea turtles or sturgeon interacted with the TC. Recommendations for future TC research are provided in this technical report.
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    Hydraulic sorting of dredged sediment in a pipeline : an evaluation of the sediment distribution pipe
    (Engineer Research and Development Center (U.S.), 2024-02) Perkey, David W.; Yearwood, David C.; McFall, Brian C.; Harris, Brian D.; Hardy, Christopher J.; Welp, Timothy L.; Eckstein, Adrienne M.; Tyler, Zachary J.; Coastal and Hydraulics Laboratory (U.S.); United States Air Force Academy; Dredging Operations and Environmental Research Program (U.S.)
    The US Army Corps of Engineers (USACE) recently established a goal to beneficially use 70% of material dredged from the nation’s navigable waterways by the year 2030. Most of the sediments dredged by the USACE are heterogeneous mixtures of mud and sand, which can limit beneficial use of dredged material (BUDM) applications. Innovative technologies that can sort material during the dredging process are needed to help increase BUDM practices. This investigation sought to evaluate the ability of a sediment distribution pipe (SDP) to sort particles during transport in a pipeline. Field demonstrations were conducted during dredged material placements at Sturgeon Island, New Jersey. Velocity within the pipeline was found to be inadequate for efficient hydraulic sorting of fines (<75 μm) and produced inconclusive results. Small scale laboratory SDP experiments found that effluent from the SDP holes had an altered sediment texture compared to the initial slurry and that hydraulic sorting was occurring within the pipeline. However, outflow from the SDP holes was inconsistent, and typically >90% of the sediment mass was discharged out the end of the pipeline. Sorting efficiency of the SDP could not be accurately assessed in the current experimental configuration.
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    Erosion thresholds and rates for sand-mud mixtures
    (Engineer Research and Development Center (U.S.), 2020-07) Perkey, David W.; Smith, S. Jarrell; Priestas, Anthony M.; Coastal and Hydraulics Laboratory (U.S.); Dredging Operations and Environmental Research Program (U.S.)
    Differences in erosion behavior of non-cohesive and cohesive sediments are widely recognized. In many natural environments, sand and mud are not completely separated and occur as mixtures. Significantly less research has been conducted on the erosion behavior of sand-mud mixtures compared to the separate treatment of sand and mud erosion. Sedflume erosion experiments were conducted on sand-mud mixtures with varying mud content to define the relationships between mud content, critical stress for erosion (τc), and erosion rate. Sand-mud mixtures were prepared with three mud sources: (1) non-swelling clay (kaolinite), (2) swelling clay (kaolinite/bentonite), and (3) a swelling, natural mud from the Mississippi River. Test results showed that critical shear stresses of the mixed sediments departed from that of pure sand with mud fractions on the order of 2% to 10%. Peak τc was observed between 30% to 40% mud content, with swelling muds achieving a ten-fold increase in τc while a five-fold increase in τc was measured for kaolinite. Additionally, this study demonstrated that the introduction of small amounts (≤5%) of mud to sand reduced erosion rates by a factor of 10 to 100. This observed abatement of erosion rate has implications for the use of dredged materials in civil and environmental engineering projects.
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    Evaluating effects of dredging-induced underwater sound on aquatic species : a literature review
    (Engineer Research and Development Center (U.S.), 2019-09) Suedel, Burton C.; McQueen, Andrew D.; Wilkens, Justin L.; Fields, Morris P.; Environmental Laboratory (U.S.); Dredging Operations and Environmental Research Program (U.S.)
    At any given moment, there may be multiple underwater sounds emanating from both natural and anthropogenic sources. Dredging activities such as the excavation, transit, and placement of material generate underwater sound. This report documents research into the biological effects of underwater sound from dredging and other anthropogenic sources to help evaluate the potential ecological risks of dredging activities. Effects data generated from exposures to anthropogenic sound sources indicate that dredging-induced sounds do not pose a significant risk of direct injury or mortality to aquatic biota. A notable exception, and much less common, is blasting activities used to remove rock and other hard substrata in navigation channels. In terms of potential non-lethal responses, low-frequency sounds produced by dredging overlap with the hearing frequency ranges of select fish and mammal species, which may pose risks for auditory temporary threshold shifts, auditory masking, and behavioral responses. To better understand the ecological risk associated with dredging sounds, a risk-based approach is needed that utilizes the available data and other site-specific information appropriate for evaluating underwater sound. The information reported herein can be used in an exposure assessment as part of a broader framework for evaluating and managing underwater sound effects on aquatic life.
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    Evaluation of biodiesel fuels to reduce fossil fuel use in Corps of Engineers floating plant operations
    (Engineer Research and Development Center (U.S.), 2016-07) Tubman, Michael W. (Michael Wright), 1951-; Welp, Timothy L.; Immel, Ryan; Leitch, Robert; Coastal and Hydraulics Laboratory (U.S.); United States. Army. Corps of Engineers; United States. Army. Corps of Engineers. Philadelphia District; Dredging Operations and Environmental Research Program (U.S.)
    A study to evaluate the feasibility of using biodiesel fuel in U.S. Army Corps of Engineers (USACE) floating plant operations to reduce environmentally sensitive emissions, increase use of renewable energy, and reduce the use of fossil fuels was conducted with funding from the U.S. Army Corps of Engineers (USACE) Dredging Operations and Environmental Research (DOER) program and the USACE Sustainability and Energy Efficiency Program. This study was conducted by the USACE Engineer Research and Development Center (ERDC) and the USACE Marine Design Center (MDC), in conjunction with support of USACE Headquarters (HQUSACE) and participating USACE Districts. The study began in 2010 with a focus on the methodology to convert four working USACE vessels to biodiesel. Favorable results in regards to mechanical and operational issues cleared the way for evaluating biodiesel on additional vessels. Fourteen vessels were converted to biodiesel use in the expanded study, and additional tests of emissions and fuel usage were conducted on two vessels. This report describes the study that successfully demonstrated that use of certified biodiesel fuel (including biodiesel manufactured from soybeans and from algal oils) by suitable USACE floating plants is feasible to reduce select environmentally sensitive emissions, increase USACE use of renewable energy, and reduce the use of fossil fuels.
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    Application of long distance conveyance (LDC) of dredged sediments to Louisiana coastal restoration
    (Engineer Research and Development Center (U.S.), 2011-01) Welp, Timothy L.; Ray, Gary L.; Environmental Laboratory (U.S.); Coastal and Hydraulics Laboratory (U.S.); Dredging Operations and Environmental Research Program (U.S.); Louisiana Coastal Area Science and Technology Office
    Restoration of Louisiana’s marshes and other coastal habitats will, in many cases, require dredged sediments to provide suitable substrate. Potential restoration sites are often at great distances from the sediment source. It will require special efforts, commonly referred to as long distance conveyance (LDC), to pump sediment to the sites. For the purposes of this report, LDC projects are defined as those Louisiana coastal restoration projects that involve hydraulic transport of slurry (mixture of sediment and water) through pipeline distances of 16 km (10 miles) or greater. Pumping slurry through a long pipeline is a mature technology for bulk transport that has been used efficiently in specific applications like coal and iron ore transport. At the workshop entitled “Long-Distance Pipeline Transport of Dredged Material to Restore Coastal Wetlands of Louisiana,” the consensus of panelists and the audience (that consisted of national and international experts in the field of long-distance transport of dredged sediment and other materials by pipeline) was that there were no fundamental technological challenges to the delivery of sediment via LDC (Hales et al. 2003). The engineering challenges will be to optimize LDC design, operation, and maintenance to achieve respective strategic restoration goals in the most efficient, cost-effective, and environmentally acceptable manner possible. Technical literature was reviewed and interviews with personnel involved in LDC-related projects conducted to summarize state-of-practice LDC dredging project information. Dredging and transport methodologies in relation to LDC state-of-practice are presented, and potential environmental impacts of long distance pipeline transport across wetlands are discussed. Scientific and engineering uncertainties related to LDC optimization of dredged sediment for coastal restoration are identified. Uncertainty, as used in this context, implies a lack of predictability, structure, and information (Rogers 1995). The report’s objective is to identify these uncertainties to personnel involved in planning, designing, constructing, monitoring, and assessing future LDC demonstration projects. If efforts are applied to reduce the levels of these uncertainties in future LDC demonstration projects by applying an adaptive management approach, then the increased predictability, structure, and information gained from these demonstrations may be used to optimize subsequent full-scale LDC Louisiana coastal restoration projects.
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    Erodibility study of Passaic River sediments using USACE sedflume
    (Engineer Research and Development Center (U.S.), 2006-09) Borrowman, Thomas David; Smith, Ernest R.; Gailani, Joseph Z.; Caviness, Larry; Dredging Operations and Environmental Research Program (U.S.); Environmental Laboratory (U.S.); Coastal and Hydraulics Laboratory (U.S.)
    Erodibility experiments were performed on sediments obtained over a 15-mile stretch of the Lower Passaic River, NJ, to assess remediation options and prioritize remediation as part of the U.S. Environmental Protection Agency’s Superfund remedial investigation. A total of 28 sediment cores were extracted from 14 locations on the Passaic River. Measurements of erodibility were performed with U.S. Army Corps of Engineers’ Sedflume to determine erosion as a function of depth for different shear stresses. Additionally, bulk density, organic content, and grain-size distribution as a function of depth were determined.
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    Dredging in sediments containing munitions and explosives of concern (MEC) : ESTCP Project No. 200321
    (Engineer Research and Development Center (U.S.), 2008-08) Welp, Timothy L.; Follett, George C.; Crull, Michelle M.; Pollock, Cheryl E.; United States. Army. Corps of Engineers. Baltimore District; United States. Army Engineering and Support Center; Coastal and Hydraulics Laboratory (U.S.); Dredging Operations and Environmental Research Program (U.S.); Environmental Security Technology Certification Program (U.S.)
    This document provides guidance to personnel (e.g., planners, cost estimators, specification writers, engineers, managers, and dredging contractors) involved in dredging projects with sediment containing Munitions and Explosives of Concern (MEC). The guidance is primarily in the form of compiled information gained from experiences on past dredging projects involving MEC and was compiled from a variety of sources. This report describes the different types of dredges and dredging projects that can encounter MEC, describes how these dredges’ operational methodologies can be impacted by MEC, and summarizes past project methodology modifications that have been used to deal with MEC. Technical aspects of past MEC/dredging projects are presented with regard to engineering controls to mitigate detonation hazards, underwater MEC detection and discrimination technologies, contracting, public awareness, safety requirements, and MEC separation techniques and (where available) subsequent impacts on production rates and costs.
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    Demonstration project on dredging and marsh development using a flexible-discharge dustpan dredge at head of passes/southwest pass Mississippi River
    (Engineer Research and Development Center (U.S.), 2004-06) Welp, Timothy L.; Clausner, James E.; Mujica, Joaquin; Thompson, Doug; Boddie, George; OA Systems Corporation; Coastal and Hydraulics Laboratory (U.S.); United States. Army. Corps of Engineers. New Orleans District; Louisiana. Department of Natural Resources; Dredging Operations and Environmental Research Program (U.S.)
    The navigation channel of the Mississippi River in the vicinity of the Head of Passes (HOP) downstream of New Orleans is an area where significant dynamic shoaling occurs. During the traditional high-water period in the spring, the shoaling in this area occurs rapidly and can represent a hazard to deep-draft vessel traffic. The shoaling must be removed rapidly to maintain adequate channel depth. Currently, dredging of the channel at HOP is conducted using hopper dredges, primarily due to their mobility. Hydraulic dredges with conventional spudding systems and floating discharge pipelines, such as cutterhead dredges, are considered a safety hazard in this area due to their inability to rapidly (and consistently) move out of the way of vessel traffic. Unfortunately, hopper dredges simply move the dredged material out of the channel and redeposit it in open-water disposal sites at the heads of Pass A Loutre and South Pass. There are two disadvantages to this technique. First, the disposal sites periodically become so filled with material that the hoppers cannot bottom dump dredged material at the sites. The dredged material must be handled again at additional cost to provide sites for hopper disposal. Secondly, there is no beneficial use of the dredged material. Hopper dredges can use direct pump-out to place material beneficially in adjacent shallow open-water areas for marsh restoration, but this is considered costly and has never been done before at the HOP. This report presents the demonstration results of the dustpan dredge Beachbuilder using a flexible discharge at the Head of Passes/Southwest Pass on the Mississippi River in June 2002. Dustpan dredges equipped with a flexible-discharge floating hose and sufficient pumping capacity potentially have the mobility required for safe passage of vessel traffic and can economically pump dredged material the distances required for placement in a beneficial use scenario such as marsh construction. This report details and discusses the project activities, operational characteristics of the Beachbuilder, and feasibility of using a flexible-discharge dustpan dredge to augment the hydraulic dredging capabilities of the U.S. Army Corps of Engineers on the Mississippi and other rivers. The goal of this report is to use the project results to identify potential opportunities for reducing overall costs for channel maintenance and increasing beneficial use of dredged materials during dredging Corps navigation projects.
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    Combining the ICM eutrophication model with the SEDZLJ sediment transport model
    (Engineer Research and Development Center (U.S.), 2012-08) Cerco, C. F.; Environmental Laboratory (U.S.); Dredging Operations and Environmental Research Program (U.S.)
    This report describes the formulation of the SEDZLJ sediment transport model, coupling of the model with the ICM eutrophication model, validation of the combined codes on a simplified grid, and application of the combined codes to a prototype system. The code validation tests indicate the codes are correctly coupled. The combined codes meet specified performance criteria including: 1. Mass conservation in water and bed. 2. Limited sensitivity to variations in model time-step. 3. Settling of new ICM state variables through model water column agrees with settling of original ICM state variables. 4. Transport of new ICM state variables agrees with transport of original ICM state variables. 5. Sediment bed will armor. 6. Bed erodes away smoothly. 7. Model behaves reasonably for accumulation in the bed with no erosion. Additional evaluation and testing were performed through application of the combined models to a prototype system: Lake George, Florida. The codes perform reasonably through a three-year simulation. The tests indicate, however, that realistic application of SEDZLJ requires an extensive set of field and laboratory observations.
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    Environmental enhancements and navigation infrastructure : A study of existing practices, innovative ideas, impediments, and research needs
    (Engineer Research and Development Center (U.S.), 2011-07) Fredette, Thomas J., 1955-; Foran, Christy M.; Brasfield, Sandra M.; Suedel, Burton C.; Environmental Laboratory (U.S.); Dredging Operations and Environmental Research Program (U.S.)
    The Environmental Enhancements and Navigation Infrastructure (EENI) study investigated the opportunities and challenges associated with increasing the environmental benefits of navigation infrastructure (e.g., jetties, locks, channels, and anchorages). This study sought to (1) identify existing and potential navigation project features designed with the express intent of enhancing environmental benefit; (2) identify laws, regulations, and policies (formulation boundaries) that both support and hinder such design features; (3) identify opportunities for increasing environmental benefits for navigation projects within existing formulation boundaries; (4) propose potential changes to formulation boundaries that would further increase opportunities for environmental benefits; and (5) identify potential areas where research may increase the opportunity to integrate environmental features into future projects. The study employed initial interviews, briefings, teleconferences, presentations, and the implementation of an internet-based survey and webinars to obtain the desired information. The concept of EENI was relatively new to most participants, but was viewed by 95% of the respondents as an activity for which there is considerable opportunity. Respondents provided several examples of projects designed to increase environmental benefits and they also provided numerous new ideas for possible enhancements. These ideas spanned a wide range of navigation infrastructure.
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    Incorporation of chemical contaminants into the combined ICM/SEDZLJ models
    (Engineer Research and Development Center (U.S.), 2012-03) Cerco, C. F.; Dredging Operations and Environmental Research Program (U.S.); Environmental Laboratory (U.S.)
    This report describes two tasks. The first is the conversion of the combined ICM/SEDZLJ computer codes to parallel operation. The conversion results in order-of-magnitude speed-up of the combined codes with no adverse effects on the computation. Results from parallel operation are identical to serial operation for up to 128 processors. The second task is the incorporation of an initial toxics code into the combined ICM/SEDZLJ codes. Two toxicants are considered. The first partitions to clay/silt particles in the water and bed sediments. The second partitions to particulate organic carbon. Treatment of the new variables in the water column is analogous to the three-dimensional, finite-volume approach used for the other ICM state variables. In the bed, toxics are considered to occupy a single well-mixed layer roughly 10 cm in thickness. This approach is adopted from the ICM sediment diagenesis model. Particle deposition and erosion and the resulting effects on bed thickness are taken from SEDZLJ. This framework forms the initial basis for a unified model of the aquatic carbon cycle, of particulate transport, and of toxicant processes.
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    Fishery resource utilization of an estuarine borrow pit in Mobile Bay, Alabama
    (Engineer Research and Development Center (U.S.), 2014-07) Reine, Kevin J.; Clarke, Douglas G.; Ray, Gary L.; Environmental Laboratory (U.S.); Dredging Operations and Environmental Research Program (U.S.); United States. Army. Corps of Engineers. Mobile District; HDR, Inc.
    Many inshore coastal habitats have been altered by sand excavation for commercial and beach nourishment purposes, producing artificial holes and depressions. These features are characterized by poor sediment, water quality, altered circulation patterns, water column stratification, and the accumulation of fine sediments. These parameters are frequently cited as factors for degraded habitat found in borrow pits. This report summarizes the results of baseline and Year 1 post-restoration monitoring of Brookley (partially restored) and Airport Holes (control), located in Mobile Bay, Alabama. Monitoring efforts included a combination of fisheries acoustic techniques to determine fish density and spatial and temporal distribution patterns, conventional fisheries to determine species composition, length, CPUE, water quality, and sediment grain size analysis. Benthic macroinvertebrates were sampled seasonally to evaluate recruitment and community structure. Postrestoration results indicated a significant improvement in water quality conditions in Brookley Hole. Hypoxic/anoxic conditions present during prerestoration were absent during postrestoration sampling. Prerestoration infaunal sampling indicated that both holes supported impoverished benthic assemblages comprised largely of opportunistic, disturbance-adapted infauna. Species abundance increased significantly during postrestoration sampling; however was still depressed when compared to the surrounding bay waters. One contributing factor is that water depths in Brookley Hole are still greater than the surrounding bay waters. There was no significant difference in abundance, taxa, or species composition among sites or the pre- and postplacement time periods, indicating that finfish utilization was not affected by the placement of dredged material. Brookley Hole remains a suitable candidate for either partial or complete filling with dredged material.
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    Characterization of underwater sounds produced by trailing suction hopper dredges during sand mining and pump-out operations
    (Engineer Research and Development Center (U.S.), 2014-03) Reine, Kevin J.; Clarke, Douglas G.; Dickerson, Charles; Wikel, Geoff; Bowhead Information Technology Services; United States. Bureau of Ocean Energy Management; Environmental Laboratory (U.S.); Wallops Flight Facility; Dredging Operations and Environmental Research Program (U.S.)
    Underwater sounds were characterized for three trailing suction hopper dredges (TSHD) during the removal of 3.1 million yd³ of sand from an offshore borrow area and during offloading of the excavated sediment at the pump-out stations in support of the Wallops Island, Virginia Beach Stabilization Project. Sounds were recorded simultaneously at two depths, 3 and 9.1 m from the surface. Sound sources included sediment removal, pump-out of material, pump-out of clear water during pipe flushing, and transit to the borrow site (hopper empty) and to the pump-out stations fully loaded. Received and 1/3-octave Sound Pressure Levels (dB re 1 μPa, rms) are reported for each sound source. Source Levels (dB re 1μPa-1m, rms) were back-calculated using fitted regression (15.788LogR). Source Levels (SL) ranged from 161.3 dB to 176.7 dB re 1μPa-1m rms. Highest SL were obtained for the dredge Liberty, which is nearly twice the size (e.g. hopper volume, displacement) of the dredges Padre and Dodge Islands. Sounds emitted during transit produced the highest SL, whether the hopper was empty or full. Attenuation to ambient was dependent on the sound source, and ranged from 0.85 km (flushing pipes) to 2.65 km during transit with the hopper at maximum capacity.
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    Economical treatment of dredged material to facilitate beneficial use
    (Engineer Research and Development Center (U.S.), 2014-08) Estes, Trudy J.; McGrath, Christian J.; Dredging Operations and Environmental Research Program (U.S.); Environmental Laboratory (U.S.)
    Growing constraints on conventional dredged material disposal are motivating movement toward more sustainable alternatives. Given the lack of universal beneficial use criteria, even the low levels of contaminants typically found in navigation channel sediments may limit or preclude their beneficial use. Intensive treatment to remove or destroy contaminants in such sediments is typically too costly to be a viable alternative within the context of navigation dredging; economical, low tech sediment and water treatment processes are needed. Recent developments in the area of sediment treatment were assessed through an extensive literature search, and promising technologies were identified. Potentially high value research areas were also identified, to inform subsequent bench and pilot testing. Geochemical contaminant controls and modeling, passive water treatment methods for colloid and ammonia removal, H2S controls, in-CDF biodegradation, aerobic/anaerobic composting, phase specific physical separation, low temperature thermal treatment, reactive geobags, and coupled geochemical/stabilization process modeling were areas identified as deserving of additional research investment.
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    Summary of a regional workshop on monitoring programs for the interior least tern (Sternula antillarum) - Tulsa, Oklahoma, 15-16 November 2005
    (Engineer Research and Development Center (U.S.), 2006-12) Lott, Casey A.; Pashley, David N.; Environmental Laboratory (U.S.); American Bird Conservancy; Dredging Operations and Environmental Research Program (U.S.)
    This technical report summarizes a regional workshop on monitoring programs for the Interior Least Tern (ILT) (Sternula antillarum) in Tulsa, Oklahoma in November, 2005. Discussions focused on: 1) defining goals and objectives for local, regional, and range-wide monitoring programs; 2) deciding what information to collect during monitoring programs; 3) standardizing data collection and analysis protocols among programs; 4) integrating local efforts into regional or range-wide approaches; and 5) evaluating the effects of management actions on ILT within the context of regional or range-wide recovery. This summary reviews existing monitoring programs and suggests a course of action for developing a range-wide monitoring plan to better evaluate the effects of management on ILT. Consensus was that annual range-wide counts of adults during a standard survey window would be advisable to track long-term changes in ILT population trends and distribution. Participants agreed that data on reproductive success (and how this relates to management) are also necessary to evaluate population health. However, many participants were concerned that estimates of fledglings per pair for Least Terns may be highly inaccurate. Participants agreed on ways to pursue monitoring of nest success (and nest fates) as indices to reproductive performance that could be analyzed versus factors associated with management issues (e.g., flooding on dam controlled rivers, recreation impacts). Two monitoring committees were formed to advise the ILT Working Group in this process.
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    Summary of first regional workshop on dredging, beach nourishment, and birds on the south Atlantic coast
    (Engineer Research and Development Center (U.S.), 2006-09) Guilfoyle, Michael P.; Fischer, Richard A., Jr., 1964-; Pashley, David N.; Lott, Casey A.; Environmental Laboratory (U.S.); American Bird Conservancy; Dredging Operations and Environmental Research Program (U.S.)
    The U.S. Army Corps of Engineers (Corps), the American Bird Conservancy (ABC), and the U.S. Fish and Wildlife Service (USFWS) organized a workshop on February 1-4, 2005 at Jekyll Island, Georgia. The primary goal of the workshop was to disseminate information on the beneficial use of dredged material deposition along the South Atlantic Coast for the purpose of habitat improvement, management, and conservation of colonial and non-colonial waterbirds and shorebirds. This region involves the operations of five Corps Districts including the Jacksonville, Florida, Wilmington, North Carolina, Savannah, Georgia, Mobile, Alabama, and Charleston, South Carolina, Districts. The workshop was characterized by a series of presentations from numerous Federal, state, and conservation organizations actively involved in the monitoring and managing of dredged material deposition for the beneficial use of habitat improvement for birds and other wildlife species. The workshop began with several presentations that identified birds of conservation concern and their habitat relationships along the Atlantic Coast (Session I). The presentations then focused on the impacts of beach nourishment (Sessions II-VI), and the use of dredged material islands by colonial and non-colonial waterbird and shorebird species (Session V). The final Session (Session VI) focused on the importance of small and regional-scale monitoring efforts, and available resources to access databases and general information on coastal bird conservation. In general, the presentations highlighted the status of current efforts to promote bird conservation in Corps operations, and emphasized areas where improvements can be made. These areas include: 1) Identification of important inlets and other areas for birds along the Atlantic Coast; 2) Link current conservation of birds in the South Atlantic Coast District regions with regional bird conservation plans already developed; 3) Improve data acquisition, database storage and accessibility; 4) Engage local communities to promote conservation alongside of recreational and economic interests; and 5) Improve our abilities to integrate issues of scale, including local, regional and national impacts of Corps activities on the conservation of many waterbirds and shorebird populations.
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    Distribution and abundance of the interior population of the least tern (Sternula antillarum), 2005 : a review of the first complete range-wide survey in the context of historic and ongoing monitoring efforts
    (Engineer Research and Development Center (U.S.), 2006-11) Lott, Casey A.; Environmental Laboratory (U.S.); American Bird Conservancy; Dredging Operations and Environmental Research Program (U.S.)
    The interior population of the Least Tern (Sternula antillarum) was added to the U.S. Fish and Wildlife Service (USFWS) list of threatened and endangered species in 1985 because of suspected low numbers and concerns about breeding season habitat loss or degradation on large interior rivers. Range-wide survey data were incomplete when Interior Least Terns (ILT) were originally listed. Although many ILT counts have been conducted over the past 20 years, regular survey coverage is still incomplete across the large breeding range of ILT, limiting the ability to assess the conservation status or trends for this population. During the last two weeks of June and the first week of July 2005, over 140 participants contributed to the first complete range-wide survey for ILT (see acknowledgments). The primary objectives of this survey were 1) to provide a minimum count of the number of adult ILT occurring in North America during the breeding season, 2) to document the range-wide distribution of nesting colonies, and 3) to describe the types of habitats that are being used for nesting. Survey crews covered ~4,700 river miles, 22 reservoirs, 62 sand pits, 12 industrial sites, 2 rooftop colonies, and over 16,000 acres of salt flats, counting a grand total of 17,591 ILT in association with 489 different colonies. Just over 62 percent of all adult ILT were counted on the “Lower” Mississippi River (10,960 birds on 770+ river miles). Four additional river systems accounted for 33.3 percent of the remaining ILT, with 11.6 percent on the Arkansas River system (including the Canadian and Cimarron Rivers and the Salt Fork of the Arkansas River), 10.4 percent on the Red River system, 6.9 percent on the Missouri River system, and 4.4 percent on the Platte River system. Lesser numbers of terns were counted on the Ohio River system (1.0 percent), the Trinity River system in Texas (1.0 percent), the Rio Grande/Pecos River system in New Mexico and Texas (0.8 percent), the Wabash River System (0.6 percent), two reservoirs in East Texas (0.3 percent), and the Kansas River system (0.3 percent). A majority of adult terns were counted on rivers (89.9 percent), with much smaller numbers at sand pits (3.6 percent), reservoirs (2.5 percent), salt flats (2.3 percent), industrial sites (1.4 percent), and rooftops (0.3 percent). This report discusses the results of the 2005 survey at three different spatial scales: 1) the entire breeding range for ILT and adjacent breeding populations on the Gulf Coast; 2) regional analyses by major river systems; and 3) individual survey segments (some of which have been combined into geographic segments comprised of more than 1 similar survey segment). Results of the 2005 survey are also compared with historic survey data from 1986 through 2004. The value of historic data for local, regional, and range-wide analyses of population trends is evaluated in the context of this first complete picture of the breeding distribution of ILT. Recommendations are made to 1) increase annual survey coverage for ILT to include several important breeding areas documented in this report that do not receive regular monitoring attention; 2) conduct additional large-scale surveys (such as the 2005 survey) during a standard survey window for long-term analyses of range-wide population trends; 3) conduct double-sampling to calculate detection ratios that will describe relative bias among survey segments with different survey methods; allowing unbiased estimation of population size and trend; and 4) improve long-term data storage for ILT count data through the development of a centralized data management system. The 2005 range-wide survey was a large collaborative effort that represents a major step forward toward developing the framework for a range-wide ILT monitoring program.
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    Dredging effects on eelgrass (Zostera marina) distribution in a New England small boat harbor
    (Engineer Research and Development Center (U.S.), 2005-07) Sabol, Bruce M.; Shafer, Deborah J.; Lord, M. Elizabeth; Environmental Laboratory (U.S.); Dredging Operations and Environmental Research Program (U.S.)
    While speculation on effects of dredging on seagrass beds is plentiful, actual empirical data documenting these effects are not. In this study, acoustic-based seagrass mapping techniques were used to generate detailed maps of seagrass distribution before and after dredging operations. Eelgrass (Zostera marina) within Scituate Harbor, MA, was monitored during mid-summer in 2001, 2003, and 2004; navigation maintenance dredging of the harbor was performed during fall 2002. Similar surveys were also performed during the same timeframe at an undredged harbor near Wood Island, ME. Two types of potential impacts were examined. Direct impacts involved physical removal of vegetation along with the dredged sediments. Indirect impacts in adjacent undredged areas may occur as a result of increased turbidity and/or siltation associated with dredging activities. Using hydroacoustic techniques, the authors were able to easily map and quantify direct impacts to eelgrass resources. Assessment of indirect impacts, however, was more complex. In the first postdredging survey, a substantial reduction in coverage occurred in adjoining undredged areas, suggesting possible indirect impacts. This was followed by a modest recovery between the first and second post-dredging years. However, monitoring of other undredged sites within the region showed natural year-to-year variations in eelgrass coverage to be almost as large as those occurring at the dredged site. Results emphasize the need for long-term data to discern any potential effects of dredging on seagrass dynamics as opposed to a host of other factors contributing to high variability in measured parameters.
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