Coasts, Water, and the Environment
riverine, estuarine, and coastal processes numerical modeling
Given the emphasis on preserving or enhancing the environment, one of the more critical aspects affecting the regulatory approval of new projects is the assessment of its impacts on the existing environment. Moffatt & Nichol’s participation in these impact assessments typically involves our capabilities to analyze riverine, estuarine, and coastal processes through the use of advanced numerical models to study the with and without project effects on hydrodynamics (water level, waves, currents, flooding), sediment transport, erosion and deposition, and water quality. We have extensive knowledge of physical processes active in these locations acquired through the completion of hundreds of affected projects which is aided by numerical model investigations and simulations. Moffatt & Nichol has completed hundreds of modeling studies, using multiple commercial and public domain modeling platforms, throughout the world – this includes having completed analyses of most of the major estuaries and coastal bays along the East, Gulf, and West Coasts of the United States. Many of these modeling studies were subjected to rigorous review and acceptance by project stakeholders, including the environmental and regulatory community, as part of the environmental review process.
Moffatt & Nichol’s analysis of sediment transport examines changes to the equilibrium of a coastal environment typically resulting from natural (e.g., storms) or manmade (e.g., dredging) events that relocate sediment.These analyses are used to predict the results of an event or the potential impacts of a project by examining the physical evolution of the area following that event. Physical mechanisms examined include erosion or deposition as a result of existing or changes to currents, waves, tides, or water parameters (e.g., density, temperature, chemistry).
To examine sediment transport, erosion, and deposition, Moffatt & Nichol uses efficient and proven analytical methods developed in-house as well as sophisticated commercial and publically-available numerical models.Moffatt & Nichol has applied these methods extensively throughout the world for shoreline and harbor improvement or damage projects including some of the largest channel deepening projects undertaken in the United States (e.g., New York/New Jersey harbor deepening study).
In the relatively new era of ecosystem awareness, Moffatt & Nichol frequently provides planning, scientific,and engineering services for projects that involve conservation, enhancement, and/or restoration. Often such projects are mitigation components that allow larger projects to proceed and, as such are subject to greater scrutiny because of the involvement of regulatory agencies. These components typically increase the number of stakeholders, increase a project’s visibility, and can require significant coordination among those stakeholders – public, government agency, and non-governmental organizations.
For such projects, improvement strategies often involve modification of the water parameters in the ecosystem (e.g., changing the freshwater or saltwater inflow or distribution), providing enhanced locations/regimes for flora &/or fauna, and protecting those improvements from adverse changes (e.g., shoreline stabilization). Having addressed each of these aspects in many successful restoration projects, Moffatt & Nichol offers experienced personnel with a strong track record of success in providing planning, numerical modeling, permitting, engineering, design, construction services, public involvement, and monitoring of ecosystem restoration projects.
regional sand management
Historically, shoreline improvement projects were planned and designed on a case-by-case basis without regard for their potential impacts on neighboring shorelines or the complete littoral system. More recently such projects have been considered on a regional basis; this has been particularly true for projects involving sand placement. As part of planning such projects, Moffatt & Nichol has provided Federal, state, and local agencies with services that have included stakeholder and public outreach, sediment transport modeling, shoreline change analysis, and other comprehensive studies of the complete littoral zone, to help them manage coastal sediments as a regional resource or to coordinate shoreline protection efforts among neighboring coastal communities.
Given the dynamic nature of the coast, many of the world’s shorelines experience dramatic changes that can necessitate intervention to preserve recreational opportunities and/or protect existing infrastructure. For decades, Moffatt & Nichol has successfully completed beach nourishment projects for a host of public and private clients ranging from the Federal government (beaches in major urban centers) to individual corporations (secluded resort beaches). Supporting those projects, Moffatt & Nichol has provided planning, permitting, community outreach, shoreline modeling and analysis, littoral budget development, storm damage and benefit analysis, identification and evaluation of sand sources and dredging alternatives, engineering, design, construction document preparation, and bid and construction services.
Inlets are among the most important elements of the coastalsystems. Physically, they are central to the workings of littoral processes and therefore anchor and dictate shoreline behavior by dominating those processes in their region. For example, they allow for the exchange of water, sediment, andnutrients between the bays and the oceans and play a significantrole in barrier island evolution processesas well as have a significantimpact on the stability of adjacent shorelines and stormsurge propagation into inland bays. Additionally, they provideimportant, and often irreplaceable, navigation access between those sheltered inland bays and open ocean.
Successful inlet management requires a thorough understanding and extensive assessment of inlet and shoreline dynamics. Moffatt& Nichol has honed our skills and tools used to analyze those dynamics and other relevant issues through analysis and evaluation of some of the most important and dynamic coastal inlets in North America. This experience includes:
- Stability analysis (individual and multiple inlets)
- Barrier island breaching and new inlet development
- Ebb and flood shoal evolution
- Sediment budgets
- Detailed wave, hydrodynamic, sediment transport, and morphologicalmodeling
- Channel shoaling estimates
- Stabilization structures
- Mechanical bypassing systems
- Navigation analysis
- Inlet channel optimization (layout and dimensions)
- Assessment of inlet impacts on bay hydrodynamics and water quality
dredged material management including beneficial re-use
Historically, dredged material was regarded as “spoil” to discard whereas more recently dredged material has been recognized as a valuable resource for wetland creation, beach renourishment, and other similar projects. With our specialization in coastal engineering, Moffatt & Nichol has worked continuously from our founding on dredged material management plans and projects including many involving beneficial reuse of that material. In particular, Moffatt & Nichol has an extensive and successful record of experience with dredging projects for the U. S. Army Corps of Engineers, various port authorities, and international governments. Typical projects have included upland, shoreline, nearshore, and offshore material dredging and placement accomplished for a variety of reasons including deepening berths, basins, and navigation channels, emergency or maintenance dredging, habitat/land/harbor creation or restoration, other beneficial uses, and reactivation of former placement sites.
Many of our dredging projects have involved high-end numerical hydrodynamic and sediment fate modeling (one-, two-, and three-dimensional) and included permitting, Long Term Management Strategies, Dredged Material Management Plans, and/or construction documents. We also have the ability to provide “risk-based” quantity estimates and opinions of probable costs where the project design uses an acceptable risk criterion for design. We have completed dredging for projects ranging from incidental quantities as small as 5,000 cy up to port backland creation involving 26 million cy (the largest such land creation project in the United States.)
coastal transportation system vulnerability
As the population density continues to increase near our shores and infrastructure is built to support that increase, the vulnerability of that population and infrastructure to damage from coastal storms as well as more gradual damage from long-term changes has become a focus of interest as governments attempt to budget initial and maintenance expenditures. As history shows, these increases in population and infrastructure have led to related increases in budgets which can be acerbated by their placement in more vulnerable areas. To assist with managing these expenditures, Moffatt & Nichol provides a full range of coastal planning and engineering services critical to properly assessing vulnerability and formulating appropriate design criteria that affect development. For example, assessing the vulnerability of potential coastal transportation facilities can influence the selection of more cost-effective routes or locations.
Moffatt & Nichol’s specialties pertinent to vulnerability assessment include hydrodynamic modeling, wave hindcasting, and statistical analyses to determine design criteria for storm surge elevation, wave height elevation, and current direction/magnitudes. These determinations provide the foundation for coastal morphological analyses, scour analyses, vessel collision analyses, and storm water management that affect the location and design of for coastal roads and bridges.
Throughout history man has attempted to control or at least influence, streams and rivers to prevent flooding or improve water supply, water quality, navigation, agriculture, and energy supply. Moffatt & Nichol is skilled in the planning and design of hydraulic structures used to modify streams and rivers while protecting life, property, and the environment. This experience includes levees, weirs, flood walls, dams, hydraulic training structures, locks, tide gates, flow diversions, inverted siphons, reservoirs, detention ponds, outlets, outfalls, culverts, and a variety of natural and man made channels.
As for other aspects within the specialty area of coastal engineering, Moffatt & Nichol has long been involved with the planning and design of coastal structures – breakwaters, seawalls, dikes, jetties, revetments, bulkheads, etc. – to protect/stabilize/train sections of coastlines, inlets, harbors and define land/water interfaces. We have planned, analyzed, and designed coastal structures in all waterfront environments:
- from open coastlines with deep water and exposure to tsunamis to sheltered bays with shallow water and concerns about seiche and wave setup
- from the Arctic where ice can dictate design parameters to the Equator where corrosion can, and
- from weak soils providing little support to exposed bedrock
This breadth of experience and expertise with coastal structures has been recognized by our selection to complete waterfront structure design manuals for the U.S. Navy and U.S. Army Corps of Engineers.
Whether designing them directly or providing input to other disciplines for their design, coastal structure design relies on the results of various coastal analyses that we are experts at completing – i.e. statistical analyses (wind, wave, current, storm surge), numerical and physical modeling including coastal morphological changes, and/or hydrodynamic load determination. For example, our coastal engineers regularly determine hydrodynamic loads for use by our waterfront structural engineers as one of the dynamic loads to be considered during structure design. We are deeply familiar with the issues, many unique, relevant to the design and construction of coastal zone structures including risk analysis, materials selection, structural system constructability, and the cost implications of each.
As commercial and recreational demands grow, the size and/or quantity of vessels using the world’s ports, harbors, and waterways increase which can lead to a variety of navigation issues and conflicts. Since our founding in 1945 by engineers that specialized in ports and harbors, Moffatt & Nichol has been involved in navigation planning and design projects formulated to alleviate those navigational issues and conflicts. As a result, we have completed navigation studies throughout the world for a long list of clients – typically government agencies but also for private companies (e.g. energy, military, manufacturers, shippers). In addition to navigation studies, we routinely complete vessel mooring and berthing studies. These studies utilize state-of-the-art numerical models that examine vessel maneuvering and movement both in transit and while berthed.
Vessel Navigation. Vessel navigation studies typically evaluate existing and proposed waterway characteristics for without-project and with-project conditions by examining parameters such as vessel usage/operation, navigation practices, and waterway management. Moffatt & Nichol has a wealth of experience in providing such studies including aspects such as economic analysis/impacts, transportation analysis/impacts, operating characteristics and hydrodynamics of vessel movement, and qualitative and quantitative risk assessment involving statistical analysis for alternatives considered. This experience includes both desk top and full mission bridge simulations of vessel maneuvering in waterways, harbors, and navigation lanes for a full range of potential wind, wave, and current conditions.
Mooring/Berthing. Moffatt & Nichol utilizes an array of computer models for static and dynamic analyses of vessels moored to waterfront structures and offshore moorings (single and multi-point). Models are used to evaluate vessel/cargo operations, vessel motions, mooring loads, fender requirements, and limiting environmental conditions (e.g. downtime associated with inclement weather, evacuation criteria for severe storms, the need for tug assistance or the need for berth protection).
Using the results of such studies, Moffatt & Nichol has further developed selected alternatives through the design and construction process. Typical projects have included navigation channels/turning basins, dredging, aids-to-navigation,mooring facilities, lightering operations, river training, fendering systems, and waterfront structure improvements.
With population shifts and the accompanying infrastructure demands, watershed management has become a significant issue in many previously-unconcerned locales while in others, with increased awareness of sustainability, it has become the central concern affecting development. To address these concerns, Moffatt & Nichol has prepared water resources studies that have carefully scrutinized watersheds and alternatives to manage this asset to the benefit of the community. For these studies, Moffatt & Nichol has supplied planning, modeling, analysis, alternative solutions, public outreach, permitting, engineering, design, construction documents, and bid and construction services for projects to improve and/or solve water management issues for tasks ranging from large watershed initiatives through subdivision drainage problems to runoff impacting individual property owners.
Stormwater management as a means to reduce flooding and/or water quality impacts caused by runoff has become an area of increasing interest on the part of the public and governmental agencies as their awareness of these stressorsto the environment has grown. With this increased interest, a focus has developed on smaller, proactive stormwater treatment and management near the runoff source as opposed to trying to treat runoff closer to its destination. Moffatt & Nichol has completed stormwater projects involving grant applications, watershed planning/restoration, floodplain analysis, integrated hydrologic/hydraulic modeling, permit support,stormwater BMPs, hydraulic structures, pump systems, mitigation, GIS/GPS integration, multi-agency coordination, and public outreach.
We have completed these projects in a wide range of hydrologic and topographic settings – mountains, foothills, and coastal plain – but provide rare capabilities to address such projects in the coastal plain. In coastal regions, stormwater management issues are especially complex because low relief in topography and high groundwater tables limit the placement and often impair the performance of conventional stormwater BMPs. As a result of our concentration in the coastal region, Moffatt & Nichol is completely familiar with less conventional, perhaps atypical, practices that work under these more complex conditions. As part of this familiarity and our use of complex numerical models in the coastal environment, Moffatt & Nichol also provides specialized expertise in evaluating coastal stormwater issues including the use of coupled surface water/groundwater modeling to analyze its flow and collection.
air, sediment, and water quality analyses
To assist our clients in responding to the requirements of various regulatory agencies governing the permitting of waterfront and coastal zone projects, Moffatt & Nichol has utilized existing numerical and developed an activity-based computational model to estimate the effects of potential projects on sediment, water, or air quality in the vicinity of those projects. These models are also used to develop and examine alternatives to manage sediment, water, or air quality during project construction and afterward during operation.
For sediment management, Moffatt & Nichol uses highly sophisticated numerical models to examine sediment accretion, erosion, and dredging. Similar state-of-the-practice models are used to analyze water quality of riverine, estuarine, and coastal water bodies. For example, Moffatt & Nichol has completed several projects involving the removal, placement, and isolation of contaminated sediments to prevent their reintroduction into the environment and the potential ecological risks associated with that reintroduction. These projects typically involve containment facilities that isolate chemically-challenged sediments within upland, nearshore, offshore, or sub-bottom placement areas; Moffatt & Nichol has modeled such facilities at all stages of completion.
As part of acquiring permits for projects within sensitive air emission areas, Moffatt & Nichol has developed an activity-based computational model that quantifies air emissions and integrates accepted Environmental Protection Agency (EPA) air emission factors with operational planning models developed by Moffatt & Nichol. This model has been used to model emission aspects of port development projects in highly-urbanized areas.
vessel maneuvering & traffic studies
Moffatt & Nichol has an advanced capability to provide numerical simulations of vessel movements, port operations and similar systems using a sophisticated numerical model called Simulation Language for Alternative Modeling (SLAM). This model also includes a graphics module, which provides an on-screen animated display of results. Analyses of vessel traffic flow in harbors, waterways and marinas can be made to examine flow capacities or to determine impacts of changes in operations or utilization of a harbor. Moffatt & Nichol has developed a state-of-the-art vessel traffic flow model that has been successfully applied to several projects varying in scope from commercial ship traffic in ports to boat traffic operations in marinas.
Negative impacts to water quality and aquatic habitat in our nation’s rivers, streams, lakes, estuaries and wetlands have occurred over time from multiple effects. Watershed restoration seeks to return some of these ecosystems to their approximate predisturbance conditions. This requires the comprehensive implementation of a variety of solutions or projects for which Moffatt & Nichol can provide the full range of planning, numerical modeling, engineering design, and construction services required for such projects to be successful.