Waterfront and Coastal Structures Knowledge Area  

Updated: 07-02-2018

 

INTRODUCTION

Waterfront structures serve as the transition point between seagoing vessels and the infrastructure that supports them while they are in port. Once attached to power, waste collection and other utilities support, the waterfront becomes a vibrant and dynamic city extension to the existing land-based installation. Coastal structures include aids to navigation, dry docks, fleet moorings, seawalls, groins, jetties, and breakwaters that are all designed to ensure the safe and efficient operation of the land ocean interface. Bulkheads, pilings, structural framing, decks, utility trenches, dolphins, compressed air, electric (power), steam, water, waste, and fuel lines and fender systems are additional facilities associated with waterfront and coastal structures. Similarly, corrosion prevention and control (CPC) challenges exist for large civil works structures such as dams, spillways, and other flood protection structures, especially if they are close to the coastal environment. Because the waterfront interface is extremely corrosive environment, a thorough understanding of that environment and the associated stresses placed on waterfront and coastal structures is vitally important to ensure mission support, safety, readiness and prevention of environmental contamination.

DESCRIPTION

Awareness of the issues that are associated with CPC for waterfront and coastal facilities and structures such as piers and wharves and the supporting components that comprise the structures will require the interaction of many engineering disciplines such as structural, electrical, environmental, mechanical, civil, and specialty engineering areas such as cathodic protection and paints and coatings expertise. Each discipline has an essential role to play in ensuring that the waterfront infrastructure is designed, constructed and sustained.

Photo of waterfront facilities and docks

Photo credit: MC 1st Class Christopher B. Stoltz / U.S. Navy via Reuters file

The Waterfront Environment

Understanding the waterfront environment and its risks and stresses on facilities is an absolute must for the supporting engineering disciplines. Salt water is an excellent electrolyte contributing to an aggressive corrosive environment. Hydrostatic forces, wind, salt spray, currents, tides, waves, and ice all contribute to corrosion and erosion of waterfront systems and structures. Waterfront operations and industrial activities (pollution, fuels, hazardous materials, deicing salts, and stray currents) often add to the corrosion severity. Wood destroying organisms such as marine borers, insects, and, fungi can cause significant damage and deterioration of marine timber structures. Environmental Severity Classification (ESC) for waterfront is typically C5 (Very High Corrosivity), and must be addressed in planning, design, material selection, and construction processes.

Photo of waterfront facilities and docks

 

Waterfront Zones

The type of CPC implemented for components or portions of a structure is influenced by the zone in which it resides:

  • The Atmospheric Zone is any portion of the waterfront structure above the splash zone.

  • The Splash Zone is the portion of the structure just above the tidal zone. This portion of the structure is predominantly dry, but is likely to intermittently wet by wave action and wind driven spray. See Figure 1 for a depiction of the Coastal Zone and Transitions. In UFGS 03 31 29 Marine Concrete the splash zone is defined as:

    • 2 meters above the tidal zone for locations protected by seawalls or sheltered from open-ocean waves;

    • 6 meters above the tidal zone for unprotected locations

  • The Tidal Zone is defined as the portion of the structure that is located between Mean Lower Low Water (MLLW) and Mean Higher High Water (MHHW); In areas with minimal tides, this would be defined as the area located between Mean Sea Level (MSL) and Mean High Water (MHW).

  • The Submerged Zone is the submerged portion of the structure that is located below Mean Lower Low Water (MLLW). In areas with minimal tides, it would be defined as that portion of the element below Mean Sea Level (MSL).

Understanding the interaction between each zone such as differential aeration cells, will often dictate the appropriate use of coatings, encasement, and cathodic protection strategies.

Graphic of the waterfront zones

Waterfront and Coastal Zone Protection Techniques

Methods of CPC in the Waterfront and Coastal Zone include:

  • Planning and applying CPC design and construction
  • Appropriate material selection
  • Utilization of protective coatings
  • Leveraging cathodic protection (For more information review the Cathodic Protection Basics training module and the CP Knowledge Area)
  • Creating and managing an active Waterfront Sustainment, Restoration and Modernization (SRM) Program

Through understanding the severity and stresses associated with the waterfront environment and the associated waterfront zones, the design, construction and sustainment of new and existing facilities will have a greater possibility of meeting mission requirements over the life cycle. It is essential that the right materials are selected, installed and maintained. The waterfront is a high stress area for utility systems, pipelines, steel structures, concrete and reinforcing steel, and timber. Typically, a higher degree of CPC is required. For instance, concrete structures will require more cover over reinforcing steel and the addition of complementary cementing materials, such as fly ash to reduce permeability. New materials that are corrosion resistant such as fiber reinforced plastics (FRP), ultra-high molecular (UHMW) plastics, and high density polyethylene (HDPE) are now in use. Where and when to use this enormous combination of materials to create a viable and productive fabric of facilities in the waterfront and coastal zone requires skill, coordination and current knowledge. The engineering and sustainment professional should seek assistance of SMEs in this diverse and complex area to ensure that their projects will survive in this dynamic zone. (See also the: Waterfront and Coastal Structures Training.).

Waterfront Utilities Considerations

Corrosion prevention and control requirements for utilities in the waterfront area is required and is covered in UFC 4-150-02 Dockside Utilities for Ships Service, UFC 3-570-01 Cathodic Protection, and UFC 3-570-06 O&M: Cathodic Protection. Corrosion resistant material selection impacts distribution lines, supports, covers, access panels along with how each line connection is made which also include the appropriate grounding techniques. Attention to these details will ensure that the required utility services will be available on demand throughout the anticipated life cycle. See Figure 2 for an example of waterfront utility distribution line details.

Example Elevation Details - Waterfront Distribution Lines

 Example Elevation Details – Waterfront Distribution Lines

Consulting Technical Discipline Subject Matter Experts (SME) associated with the Waterfront Environment

The Waterfront and Coastal Discipline Area SMEs (see the Assistance section at the end of this page) provide invaluable consultation skills developed from years of experience assessing corrosion prevention requirements and many environments. The SMEs can translate local conditions into the interdisciplinary solutions that provide immediate and long-term benefits to the installation and its SRM bottom line costs. Typical consulting services provided by the SMEs include:

  • Multi-discipline coordination and understanding
  • Materials analysis and selection
  • Problem assessment
  • Failure analysis
  • Environmental Severity impacts
  • System and material selection
  • Review and assessment of contractor deliverables
  • Quality assurance
  • System design
  • SRM analysis and recommendations (system inspection and testing assistance)
  • Hazards analysis
  • Assessment of new technologies
  • Process analysis
  • Anti-terrorism threat analysis and protection technologies

Relevant Codes and Standards

Department of Defense

Unified Facilities Criteria (UFC)

Unified Facilities Guide Specifications (UFGS)

U.S. Army Corps of Engineers - Public Works Technical Bulletin (PWTB)

National Association of Corrosion Engineers (NACE) and Society for Protective Coatings (SSPC)

  • SP0169, Corrosion Control of External Corrosion on Underground or Submerged Metallic Piping Systems
  • SP0285, Corrosion Control of Underground Storage Tanks by Cathodic Protection
  • SP0388, Impressed Current Cathodic Protection of Internal Submerged Surfaces of Steel Water Storage Tanks
  • RP0193, External Cathodic Protection of On-Grade Metallic Storage Tank Bottoms
  • SP0196, Galvanic Anode Cathodic Protection of Internal Submerged Surfaces of Steel Water Storage Tanks
  • Steel Structures Painting Council (SSPC) Paint No. 16

National Electrical Manufacturers Association (NEMA)

  • ANSI /NEMA C57.12.29 2006 Electrical Standards and Product Guide

ASTM International

  • ASTM A242 Standard Specification for High-Strength Low-Alloy Structural Steel
  • ASTM A588/A588M–15 Standard Specification for High-Strength Low–Alloy Structural Steel, up to 50ksi [345 MPa] Minimum Yield Point, with Atmospheric Corrosion Resistance
  • ASTM A606/A606M-18 Standard Specification for Steel, Sheet and Strip, High-Strength, Low-Alloy, Hot-Rolled and Cold-Rolled, with Improved Atmospheric Corrosion Resistance
  • ASTM A690/A690M-13a (H-Piles and Sheet Piling)Standard Specification for High-Strength Low-Alloy Nickel, Copper, Phosphorous Steel H-Piles and Sheet Piling with Atmospheric Corrosion Resistance for Use in Marine Environments
  • ASTM A709/A709M-17 Standard Specification for Structural Steel for Bridges

ADDITIONAL RESOURCES

Organizations

  • SSPC (The Society for Protective Coatings) Training and Certification
  • STI (Steel Tank Institute) Training and Certification