Dredging Creates a Strong Economy and a Cleaner Environment

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Frequently Asked Questions

What is WEDA?

WEDA is a technical professional organization devoted to the exchange of knowledge in fields related to dredging, navigation, marine engineering and construction.

What is the mission and the objectives of WEDA?

    To promote the exchange of knowledge in fields related to dredging, navigation, marine engineering and construction by sponsoring or co-sponsoring national and international technical conferences, seminars, and symposiums, including publication and dissemination of the proceedings.
    To emphasize the importance of understanding and development of solutions for problems related to the protection and enhancement of the marine environment.
    To support educational institutions for students interested in pursuing dredging and marine engineering as a career.
    To promote membership in and furtherance of the Western Dredging Association through establishment and support of Chapters.
    To recognize individuals and organizations for outstanding engineering and operational achievement.

Who are the members of WEDA?

Members of WEDA include professionals in the field of dredging, navigation, marine engineering and construction, including representatives of the industry, equipment manufacturers, consultants, academia, environmental interest groups, and federal, state, and local governments. Members are from the Western Hemisphere, including North America, Latin America, and South America.

Why should I join WEDA?

Two words: knowledge and networking. Your membership will also provide additional knowledge/expertise and viewpoints that can help members meet the current industry challenges in getting the job done in an effective and efficient manner while meeting environmental goals.

How do I join?

Join through the WEDA Website by clicking HERE, email the WEDA Executive Director Thomas Cappellino, or join at a WEDA Chapter or national meeting.

When and where are WEDA’s annual conferences?

WEDA has an annual national conference that is held in different locations throughout the USA, typically in June. This technical conference is held in conjunction with Texas A & M’s Annual Dredging Seminar. There are also four regional WEDA chapters within the U.S. (Pacific, Gulf, Midwest, and Eastern chapters) as well as chapters in Panama, Brazil, and Mexico. All of the chapters meet on an annual basis, at different locations within the various regions. These annual meetings involve both technical presentations and chapter business. Locations and registration information for all of these meetings can be found on the WEDA Website.

How does WEDA operate? Who does it?

The Executive Director is to be the overall manager of WEDA and provides input to the WEDA Board of Directors with respect to all aspects of the WEDA mission. The Executive Director handles all day to-day functions of WEDA, including memberships, mailings, conference arrangements and negotiations and interactions with related organizations, as well as coordination with WEDA chapters, and EADA (Eastern Dredging Association) and CEDA (Central Dredging Association ), and WODA (World Organization of Dredging Associations). The Executive Director is Thomas P. Cappellino, who can be reached at Tcappellino@westerndredging.org.

What is WEDA’s Environmental Commission?

The goal of the Environmental Commission is to promote communication and understanding of environmental issues and stimulate new solutions associated with dredging and placement of dredged materials such that dredging projects, including navigation and remediation dredging, are accomplished in an efficient manner while meeting environmental goals. The Commission meets annually during the WEDA national conference, and is open to all attendees of WEDA. The Commission sponsors a technical panel during the annual WEDA national conference and awards the annual WEDA Environmental Excellence Award for a navigation dredging project and for an environmental dredging project.

What is WODA?

The World Organization of Dredging Associations (WODA) is a non-profit professional Organization, dedicated to the exchange of knowledge and information related to dredging, navigation, marine engineering and construction. It is comprised of three dredging associations - WEDA, CEDA and EADA, respectively, the Western, Central and Eastern Dredging Associations. The three dredging associations meet once every three years under the name of WODA in a technical conference, rotating the sponsorship between the three. WODA’s mission encompasses the objectives of WEDA, CEDA, and EADA and includes:

    To promote the development and exchange of professional knowledge, - scientific, technical, regulatory and managerial - in all fields concerned with dredging and handling or placement of dredge material;
    To participate in the development of international and national policies, regulations, and guidelines on dredging and related matters;
    To balance the environmental, social and economic concerns related to dredging and dredged material handling or placement projects and to encourage open communication between all stakeholders; and
    To enhance contacts between individuals and various professional entities concerned with dredging and associated matters and between the dredging community and the society in which it works.

Dredging and Dredged Material Management

What is dredging and why dredge?

A simple definition of dredging is the subaqueous or underwater excavation of soils and rock. The process consists of four phases: excavation, vertical transport, horizontal transport and placement or use of the material dredged.

From the beginning of civilization, people, equipment, materials, and commodities have been transported by water. To do this, the channel depths of many waterways needed to be increased to provide access to ports and harbors. Most major ports in the world require dredging at some time to enlarge and deepen access channels, waterways, and turning basins, and to provide appropriate water depths along waterside facilities. These channels often require frequent and regular maintenance dredging. In the case of fluvial navigation, dredging is also required to construct and maintain vital links to inland ports and facilities.

As population density along the coastlines and riverbanks increases, dredging is also used for to protect against flooding and erosion, as well as to create recreational facilities like beaches through sand nourishment.

Dredging is also used for the installation of energy facilities such as offshore drilling platforms and oil and gas pipelines and the construction of wind farms in the water. Dredging can also be used to recover minerals, gems, precious metals, and fertilizers, or the removal of overlying material to reach such deposits.

Dredging can also provide construction materials such as sand, gravel, shell and clay, or provide landfills, including the construction of industrial and residential areas, highways, dams, airports, causeways and habitats for birds and other forms of wildlife.

Another more recent use of dredging is to remove or remediate subaqueous pollutants and improve water quality and sediment habitats. This type of dredging operation is used as a means to clean-up contaminated waterways. Environmental dredging is the removal of contaminated sediments from a water body for purposes of sediment remediation.

What is a dredge?

A dredge is a specialized type of equipment that is used for excavation and transportation of dredged materials. Ways of describing types of dredgers can vary but, generally speaking, the types of dredges are described by four broad classifications on the basis of the mode of excavation and operation:

    Mechanical dredges – grabs, clamshells, bucket-ladders, backhoes
    Hydraulic dredges – plain suction and dustpan
    Mechanical/hydraulic dredges (utilizing both basic elements in some combination) – trailing suction hoppers, cutters, bucket-wheel;
    Hydrodynamic dredges – Water injection dredges, ploughs, beams and rakes.

Within these categories, dredges can also be defined as self-propelled or stationary. There is also a variety of specialized environmental dredges, as well as auxiliary equipment such as barges, boosters and pumps.

The difference between these mechanical and hydraulic equipment types is the way that the sediment is excavated. Mechanical dredging is done by means of various knives, teeth, or other cutting edges, and is typically used in areas with cohesive soils such as native formations. Hydraulic dredging makes use of the erosive working of a water flow generated by a dredge pump; the flow erodes the sediment bed and forms a sediment-water mixture before it enters the suction pipe. This type of dredging is typically used in areas with cohesionless soils such as silt, sand, and gravel. However, the choice of dredging equipment also depends on such factors as site accessibility, weather and wave conditions, anchoring conditions, required accuracy, and disposal location.

Mechanical dredges include the bucket ladder dredge, the clamshell dredge, and the backhoe/front shovel crane dredges. Hydraulic dredges include the plain suction dredge, the barge unloading dredge, the cutter suction dredge, the bucket wheel dredge, and the trailing suction hopper dredge. All dredges except the trailing suction hopper dredgers are stationary dredges, meaning that they are anchored by wires or (spud) poles during operation. Transfer of dredged material is accomplished by different means depending on the dredge equipment, typically via pipe, bucket, or bottom dump.

What are the benefits of dredging?

Dredging provides important economic and environmental benefits. Dredges excavate channels, berths, and turning basins to support recreational and commercial transportation. Ships and barges utilize these channels to import and export goods critical to our local, regional, and national economies. Dredges maintain these channels to authorized depths by removing sediment that deposits naturally from inflowing streams and rivers.

Dredges are also used to remove sediments contaminated by historical industrial operations. These sediments release chemicals to the biota and water column and are often the reason for fishing advisories. Removing these sediments is an important component of restoring a healthy ecosystem.

Who is in charge of dredging and who does the dredging?

Dredging is performed by a wide variety of individuals for a number of beneficial purposes ranging from such wide purposes as: a water resource agency to improve water circulation, a private homeowner to provide water access to their nearest lake, or to a national or regional agency or a port authority for commercial navigation purposes. Dredging is also performed as a mining tool to obtain building materials or even precious minerals. The ‘people in charge’ are as varied as any tool or process with such a wide variety of uses and processes. For many of the projects in the northern hemisphere of the Americas the permitting process within waters that can be impacted by the work involve governmental agencies such as Environment Canada or the US Army Corps of Engineers, but this is not the only functionaries. Funding can be provided through private, Corporate or Governmental interests. Some projects require significant political resources to be successfully launched and completed. The dredging activity itself is accomplished by contractors for the majority of the undertakings with the exception of a small number of projects performed by the US Army Corps of Engineers fleet of dredges.

How deep do navigation channels need to be?

Navigation channel depths vary depending on the use of the water body and the anticipated vessel size. Other factors that influence the channel depth include, but are not limited to, the effects of winds, waves, tides, currents, visibility, and vessel speeds. Channel depths at major ports generally range from 35 to more than 60 feet while the waterways may range from less than 15 feet to naturally deep channels that accommodate deep draft vessels.

What does it cost to dredge, and who pays for the dredging?

Dredging projects are so varied that there is no simple answer to the question. Dredging projects may range from simple removal of a few hundred cubic yards of soft mud from a marina with an excavator and truck to the blasting and removal of tens of thousands cubic yards of rock with a complex array of specialized equipment to major port expansions removing millions of cubic yards of widely varying material.

With the varied site-specific dredging and disposal conditions, it shouldn’t be surprising that unit costs can vary by several orders of magnitude. Generally speaking, navigational dredging projects cost less per cubic yard than environmental remediation projects. As a rule of thumb, larger projects have lower removal and disposal cost per cubic yard than smaller projects due to economies of scale in handling and transporting sediments. In 2010, the largest purchaser of dredging services in the USA, the U.S. Army Corps of Engineers, spent $1.5 billion to dredge roughly 220 million cubic yards of sediment for a unit cost of less than $7 per cubic yard. [Reference]

However, for dredging projects that remediate contaminated sediments, cost figures for navigational dredging can be misleading. Frequently, the cost of the dredging is a small fraction of the total project costs for managing, treating, and disposing of sediments contaminated with hazardous materials. Total project costs can exceed $500 per cubic yard for complex sediment remediation projects.

Funding sources are similarly varied. Private owners usually fund removal of sediment from their private docks and berths. Government agencies or port authorities usually fund new works to create navigational channels or pay for maintenance dredging to keep those channels open. Port authorities frequently use public-private partnerships to fund expansions of harbors and terminal facilities. On environmental dredging projects, regulatory agencies may force responsible private parties to pay the costs to dredge contaminated sediments or may use a combination of government and matching funds to pay for remediation.

Environmental Aspects of Dredging and Dredged Material Management

What is the WODA Environmental Policy?

WODA adopted a policy on the environment during World Dredging Congress XV in Las Vegas, USA, 28 June -–2 July 1998. As a member of WODA, the policy applies to WEDA and it embraces environmental protection as a critical factor in successful dredging projects. It clearly states that cost-effective and timely dredging projects can be accomplished in an environmentally sound manner. The WODA Environmental Policy applies to all aspects of WODA interests including construction, maintenance, mining and remedial dredging (clean-up of contaminated sediments). View the WODA Environmental Policy

What laws and regulations are pertinent to dredging and dredged material disposal?

Dredging and dredged material disposal is heavily regulated and covered by laws at the international, federal, state, provincial, and local levels. For many of the countries in WEDA territory (i.e., Western Hemisphere), national and regional legislation and policies are based upon the international regulatory instrument, the London Convention 1972 and London Protocol 1996 (LC/LP). The LC/LP regulates disposal of wastes into ocean waters, world-wide. The LC/LP is an international treaty which includes 90 country signatories, including, but not limited to, USA, Canada, Mexico, Panama, and Brazil. Member countries are required to implement the conditions of the treaty including the waste assessment procedures noted below. The LC/LP operates under the International Maritime Organization, an organization of the United Nations. Read More...

The LC/LP Waste Assessment Guidelines for Dredged Material allow disposal of dredged material into ocean waters, provided that strict environmentally protective criteria are met. A step by step process to evaluate a dredging project, the alternatives for disposal or placement for beneficial use, and an action list for judging environmental acceptability of open water disposal are specified in the Guidelines. Read More...

Each country’s individual regulations can be found on their dredging and environmental regulatory websites. For the USA, those agencies are the U.S. Army Corps of Engineers, and the U.S. Environmental Protection Agency, For Canada, the reader is referred to Environment Canada.

If sediments are contaminated, what is done with the dredged materials?

If the objectives of the dredging are for navigation purposes, contaminated dredged materials are normally disposed of in a confined disposal facility along the shoreline or in upland locations. In a large number of cases, confined disposal has been successfully accomplished in confined aquatic cells constructed in the seabed and capped with clean material.

In cases of environmental dredging, the options are to confine the contaminated sediments in specially lined hazardous waste landfills or to treat the sediments to detoxify the sediments to acceptable levels.

How much navigation dredged material is contaminated and where is it generally found?

No distinct statistics are available to answer this question, but in the USA, it is generally thought that around 5% of dredged material is contaminated. Contaminated dredged material is the result of the legacy of uncontrolled industrial and municipal discharges and non-point discharges. Regulatory controls are now in effect in many locations but widespread contamination from discharges of the past continue to contaminate dredged materials, mostly in urban harbors and waterways.

What safeguards are in place to protect sea life, such as turtles?

Sea turtles are rigorously protected through seasonal restrictions/dredging windows for aquatic construction activities due to their presence, use of turtle exclusion devices on trailing suction hopper dredges (dredges with most turtle takes), and trawling in advance of the dredging operation to remove the turtles from the channel for transport to a distant location. Technology for other aquatic fife could be use of silt curtains, appropriate disposal site selection, and coordination with fisheries groups.

Once dredged, where are dredged materials placed?

The simple answer is: it depends. It depends upon a number of factors ranging from the physical and chemical characteristics of the dredged material to whether it is considered acceptable for open water disposal to the location of the dredging site and the potential for beneficial use of that dredged material. Placement of dredged material is commonly the first question that is answered after it is determined that dredging is necessary. Hopefully, the beneficial use of the dredged material is a feasible if not most cost effective option available to the dredger. Placement options include:

    Material is commonly placed or utilized in shore protection or coastal restoration features where adding sediment will restore or protect existing wetland habitat.
    Another option is near shore features called underwater berms that may have a dampening effect on wave energy providing additional protection to coastal features.
    Material is also spread in thin layers either above land or underwater to nourish wetlands or raise the sea bed to an elevation more conducive to sea grass habitat.
    Material is placed in confined disposal facilities, CDF’s for storage. This material may be used in construction activities, fill for construction sites, and aggregate for concrete manufacturing.
    In many cases, material is dredged and taken to open water or offshore deposition areas where it may never be used again.

Dredged material is an asset often underutilized. Identifying appropriate deposition/placement opportunities for this very valuable resource is usually not as significant a challenge as identifying a funding source that might be available to augment the “cheapest” disposal alternative.

How is dredged material tested to assess its potential toxicity or potential harm to the environment?

Once dredged material samples have been collected, chemical and in many cases, bioassays, analysis (depending on the contamination of concern) is performed on the material and the results are compared with local, state and federal regulations. Risk assessment can be performed to develop site specific goals. There are standard guidelines available for characterization and risk assessment for dredged material, for example:

    Evaluating Environmental Effects of Dredged Material Management Alterternatives - A Technical Framework
    The testing manual for dredged material proposed for ocean disposal
    The Inland Testing Manual for dredged material proposed for inland waters disposal

Within the USA, what is the role of the U.S. Army Corps of Engineers?

The Corps’ mission is to provide vital public engineering services in peace and war to strengthen the United States’ security, energize the economy, and reduce risks from disasters. Dredging is an important component of the Corps’ Navigation Mission - to provide safe, reliable, efficient, effective and environmentally sustainable waterborne transportation systems for movement of commerce, national security needs, and recreation.

The Corps’ primary navigation responsibilities include planning and constructing new navigation channels and locks and dams, and dredging to maintain channel depths at U.S. harbors and on inland waterways. The Corps operates and maintains 12,000 miles of inland and intracoastal waterway navigable channels, including 192 commercial lock and dam sites, and is responsible for ports and waterways in 41 states. In partnership with local port authorities, Corps personnel oversee dredging and construction projects at hundreds of ports and harbors at an average annual cost of over $1.3 billion. The Corps dredges over 250 million cubic yards of material each year to keep the nation's waterways navigable. Much of this dredged material is reused for environmental restoration projects including the creation of wetlands.

To support the dredging component of the navigation mission, the Corps has an extensive research and development program that provides state-of-the-art information to government agencies and private parties who need to manage dredging projects and dredged material disposal. These programs include:

    The Dredging Operations Technical Support Program, known as DOTS, provides direct environmental and engineering technical support to the U.S. Army Corps of Engineers Operations and Maintenance (O&M) dredging mission. Technology transfer activities have supported diverse field needs for years and have directly benefited O&M dredging operations throughout the United States.
    The Dredging Operations and Environmental Research (DOER) Program supports the U.S. Army Corps of Engineers Operation and Maintenance Navigation Program. Research is designed to balance operational and environmental initiatives and to meet complex economic, engineering, and environmental challenges of dredging and disposal in support of the navigation mission. Research results will provide dredging project managers with technology for cost-effective operation, evaluation of risks associated with management alternatives, and environmental compliance.

What is the role of the federal environmental protection regulatory and resource protection agencies (e.g., U.S. Environmental Protection Agency, Environment Canada)?

In general, these agencies are responsible for ensuring that dredging projects are accomplished in a manner that meets environmental protection objectives and standards. Depending upon the country and specific federal agency, national legislation specifies their roles and responsibilities protecting the numerous elements of environmental protection (e.g., water quality, sediment quality, air quality, and endangered species). More information can be found on each agency’s website.

What are the roles of the states or provinces?

Like the Corps, the states/provinces have several levels of responsibility in relation to dredging. In terms of their economy, states/provinces are responsible for promoting and developing economic opportunities for its citizens, and nothing drives an economy like a port, a waterway, or a beach or many other places where dredging starts the business. Some states/provinces have dedicated funds to leverage federal dredging programs, while others have their own dredging programs to support their constituents. At the federal level, many states/provinces actively promote their own interest against other states/provinces, while in other instances they advocate for their interests as part of a national transportation or sediment management system.

In terms of environmental issues, most states/provinces advocate for their own environmental interests (through their own regulatory agencies) by partnering with federal regulatory agencies to assure a thorough review of each dredging project. In doing so, many issues are considered and discussed including endangered species, air quality, and water quality. Sustainability and other long term management issues are also discussed. Some elements of the discussion are codified in state/province and/or local law, while other elements are subject to debate based on local sentiment and activists. The regulatory process works best when the discussion is based on science and most states/provinces serve as proficient stewards of the process to assure timely review of each issue.

Who can I talk to about dredging in my local port and waterway?

Waterways are a network of local, state/provincial, and federal channels that lead to docks and ports that may be private or public entities. The first stop should be with the Port Authority or the government entity responsible for maintaining the depth of the channels. Within the USA, the US Army Corps of Engineers (www.usace.army.mil) maintains Federal navigation channels through dredging. The local Corps District office can provide information about on-going and future dredging projects in these channels. They are also usually aware of dredging projects by private entities and other government agencies because of their regulatory role under Section 404 of the Clean Water Act. Section 404 regulates dredging and filling of waterways and wetlands. In Canada, contact Environment Canada or the individual provinces. In other countries, contact the WEDA Chapters for more information.

Can dredged material be used in a beneficial manner? Where can I find more information on beneficial uses of dredged material?

Much of the sedi¬ment dredged each year from ports, harbors, and waterways could be used in a beneficial manner, such as for habitat restoration and creation, beach nour-ishment, agriculture, mine reclamation, and industrial and commercial development. Dredged material is increasingly regarded as a resource rather than as a waste. The first step in examining dredged material management options is to consider possible beneficial uses of dredged material. Recent decades have seen the increasing use of dredged materials for habitat creation, habitat restoration, beach nourishment and coastal protection.

The US EPA-Corps Beneficial Use Manual is an excellent source of information on beneficial use and a large number of case studies are included in the Corps website. Another good resource is the Great Lakes Commission website on beneficial use of dredged materials.

Are there treatment technologies to decontaminate dredged material?

Yes, there are treatment technologies to decontaminate dredged material. They vary from insitu (in the water body with no dredging) to exsitu (out of the water body after dredging). Exsitu is more common than insitu, but neither is widely used because the cost-benefits are often not justified when compared to other more common methods of addressing contaminated sediments. These more common methods, accepted by state and federal agencies across the U.S., include monitored natural recovery (monitoring the natural burial and/or degradation of contaminated sediments over a period of time), insitu capping (containment of the contaminated sediments below a protective permeable or impermeable cap), and dredging with upland disposal in a secure engineered facility. Agency-selected remedies for contaminated sediment sites often contain a combination of these methods. Occasionally, treatment technologies are justified, and they may include thermal treatment (destroy or extract the contaminants at high temperatures), or biological, chemical, or organic additives to change the chemical make-up and render the contaminants harmless, or to fix them in place so they no longer are threats to human or ecological receptors. A good reference is PIANC’s Handling and treatment of contaminated dredged material (CDM) from ports and inland waterways.

What are effective approaches to ensure that dredging gets done in an effective manner while meeting environmental goals?

Collaboration and communication among all stakeholders is a must. Most countries within WEDA territory have a system of regulatory controls, and one successful approach to implement those regulations is to ensure that all parties understand the various forms of teams or collaborations for continued communication and understanding of the proposed projects. These teams have operated at the local, regional, and national levels.

One successful model is that used in the USA which includes a national team and regional teams. The National Dredging Team (NDT) is a federal interagency team and was established in July 1995 to promote national and regional consistency on dredging issues and provide a forum for conflict resolution and information exchange early in the process. The NDT provides a mechanism for timely resolution of conflicts by involving all agencies and maxi¬mizing interagency coordination, and serves as a forum for implementation of the National Dredging Policy.

The National Dredging Issues Team is co-chaired by EPA and the Corps and includes the following members:

    U.S. Environmental Protection Agency—Co-Chair
    U.S. Army Corps of Engineers—Co-Chair
    Maritime Administration
    NOAA’s National Marine Fisheries Service
    NOAA’s National Ocean Service
    Fish and Wildlife Service

The national team has two primary roles: (1) to review policies and proce¬dures associated with the dredging process, and to develop guidance for interaction with the Regional Dredging Issues Teams; and (2) to oversee the resolution of issues elevated from the Regional Dredging Team level. The Regional Dredging Teams include representatives from the appropriate federal and state governmental agen¬cies and stakeholders. The teams resolve local-level issues that arise during the permitting process, dredged material disposal management and planning, and new navigation project planning.

Dredging Teams (RDTs) have been established in most geographic areas in the United States:
Established RDTs

    New England RDT (Sudbury Group)
    New York/New Jersey Harbor RDT
    Great Lakes Dredging Team
    Delaware Bay RDT
    Southeast RDT
    Mississippi River Dredging Team
    Western Gulf Dredging Team
    Southern California RDT
    San Francisco Bay Long-Term Management Strategy Group
    Delta Dredged Sediment Long-Term Management Strategy
    Pacific Northwest RDT
    Honolulu and Pacific Islands RDT
    Honolulu and Pacific Islands RDT
    Puerto Rico RDT-- being established