3.3.5 Mitigation works to protect other critical infrastructure

Before you start: Use case Location: Uses GIS data: Authors:
Section 3.3.1 Landslide mitigation measures for buildings section 3.3.2 Flood mitigation measures for buildings can be read before this use case This use case is Illustrated  with the flood protection works required from the Hewanorra International airport, Saint Lucia, and the works required for protecting the city center of Castries, and works needed for Belize City No

Naveed Anwar, Mark Brussel, Mark Trigg



It is important to identify the assets and facilities that are critical to the functioning of the important operations and provision of essential services, and vulnerable to hazards. It is also important to determine the resulting consequences to those assets and to overall utility operations. Critical infrastructure must be designed, located, and sufficiently protected to remain operational during hazards. Multiple Hazards should be considered while preparing mitigation plan for critical Infrastructure as they provide essential services to daily life and of vital importance to public wellbeing such as drinking water supply, power supply, waste water disposal sites, water treatment plants, and transportation hubs.

Tourist sites and infrastructure should also be considered, both in terms of protecting points of interest for tourists in the islands(e.g. waterfalls, hot water springs), and tourists trails.

For example for the flood hazard, recent FEMA and ASCE publications recommend elevating critical infrastructure above the 500-year flood (i.e. 0.2% annual flood event) elevation, if feasible, carry out flood proofing or prevention.

In the context of critical infrastructure, hazard resilience also refers to:

  • coordinated planning across sectors and networks
  • responsive, flexible and timely recovery measures, and

The development of an organisational culture that has the ability to provide a minimum level of service during interruptions, emergencies and disasters, and return to full operations quickly (1).

Scenario based planning can be good option in assessing whether organisations have developed an adequate resilience capacity for critical infrastructures. 


The objectives on which this use case is based upon are:

  • Consider flooding as the potential hazard and risk for the critical infrastructure
  • Provide focus on mitigation works to protect other critical infrastructure, such as water supply, hydro-power dams, airports, water treatment plants, waste disposal sites etc.

Emphasize on protecting tourist sites and infrastructure, both in terms of protecting points of interest for tourists in the islands (e.g. waterfalls, hot water springs, and tourist trails (e.g. Domincia and Saint Vincent) 


The critical infrastructure could be spread on fairly large area. However, not all part of the infrastructure may be critical both in terms of the requirements for the functionality of infrastructure facility, or for hazard to the occupants or the services.

The following overall flow chart can be used as a guideline for determining and implementing the protection from floods and its consequences.

Use case study area description:

The Hewanorra International Airport terminal building, also located in Vieux Fort, was badly flooded and debris accumulated on the runway in 2013. 

Problems definition and specifications:

The measures and steps needed to protect the essential infrastructure other than building from the flood hazard and minimizing potential consequences of flooding of these facilities.

  • Facility plans and details
  • Flood risk maps

Analysis steps: A- Identify the critical Part of the facilities based on the functioning, contents, building type, and its role in the overall infrastructure.   B- Determine the risk of flooding as well as the consequences of flooding to the operation of the facility, safety of its occupants and possible impact on the environment of the area as consequences of flooding. Consider the elevation, location, building characteristics and other vulnerability factors during this assessment.   C- Determine the suitablility of protection measures which may include individual or combination of the following:

    1. Site measures 
    1. Local facility/ building measures

The site measures may include:

  • Diversion of water away from the facility
  • Drainage around and within facility either leading to gravity outlets or storage and pumping facilities
  • Construction of dykes and other levy walls or other similar protection or water barriers
  • Construction of flood plains/ retention ponds around or within the facility

The measures within the site for various facilities and buildings may be based on the section 3.2.1 Buildings of Use Case book.  


The mitigation work plan should be revisited periodically and mitigation measures that involve major capital and infrastructure investments should be integrated into the utility's overall scheduling in the asset management planning process (e.g., phasing in flood-resistant pumps).

Water and wastewater utilities are particularly vulnerable to flooding. Flood water and debris can inundate the facility and can lead to various consequences specifically disruptions of services, and hazardous situations for personnel and public health advisories.

It is also necessary to analyse how drinking water or wastewater utility may be impacted by hazardous events so that appropriate mitigation measures can be identified to eliminate or reduce asset damage and prevent service disruptions


Critical Infrastructures

Parts of Critical Infrastructures

Possible Mitigation Measures


Overall Site

  • Temporary flood barriers (e.g., sandbags) for use in minor floods
  • Permanent physical barriers (e.g., flood walls, levees,)
  • Drainage around the runway

Terminal Buildings

  • Sealed doors
  • Elevated Building
  • Water pumping system

Cargo building

  • Sealed doors
  • Elevated Building

Access roads

  • Elevated Roads
  • Drainage system

Water Supply

Overall Site

  • Temporary flood barriers (e.g., sandbags) for use in minor floods
  • Permanent physical barriers (e.g., flood walls, levees)

Water intake Distribution and storage

  • Re-grade land surrounding well field to create slope to prevent flood water from flowing toward the wells
  • Relocate or elevate well field pump houses
  • Seal the top of well casings, waterproof well caps
  • Submersible pumps or waterproof pump motors and other equipment

Booster stations and other pumps

  • Waterproof, relocate or elevate motor controls, variable frequency drives, computers and electrical panels to a higher elevation by constructing platforms or integrating controls
  • De-energize systems after flood warning to mitigate damage to electrical components
  • Sealed, waterproof conduits and submersion rated enclosures instead of electrical panels
  • Sump pumps for below-ground facilities
  • Below-grade booster station instead of an above-grade station elevated higher than the flood stage
  • Store temporary or replacement pumps out of the flood zone
  • Generator for temporary energy supply

Drinking water treatment plants

  • Saltwater-resistant equipment and storage tanks (e.g., for chemicals and fuel)
  • Waterproof electrical components
  • Elevate, relocate or cap individual assets to prevent damage from flood waters
  • Motorized and electrical equipment instead of submersible equipment (e.g., submersible pumps)
  • Energy-efficient equipment to increase the longevity of the fuel supply for backup generators
  • Process guidelines or models to understand potential water quality changes, adjustments that may have to be made to attain drinking water standards and the potential costs of changes in treatment
  • Larger capacity chemical storage tanks to ensure a sufficient supply

Electrical controls and supply

  • Waterproof electrical components (e.g., pump motors) and circuitry
  • Submersible equipment instead of motorized and electrical equipment (e.g., submersible pumps)

Hydro Power Dams


  • Sufficient Height and proper design of various parts

Power House (Generator. Transformers), Turbines

  • Solar panels or wind turbines to reduce dependence on the electrical grid and to potentially supplement backup power supply
  • Waterproof electrical components (e.g., pump motors) and circuitry
  • Submersible equipment instead of motorized and electrical equipment (e.g., submersible pumps)
  • Relocate or elevate electrical vaults and service panels outside of the flood zone

Power lines

  • Proper design of foundation of transmission towers

Control Gates

  • Adequate design for expected water levels

Water treatment Plants

Overall site

  • Physical barriers (e.g. flood walls, levee, and sealed doors)
  • Green infrastructure
  • Flood water pumping systems
  • Large storage tank to store overflows for future treatment

Lift Stations

  • Waterproof electrical components, controls and circuitry
  • Energy efficient equipment to increase the longevity of the fuel supply for backup generators
  • Replace pumps with diesel driven or dual-option counterparts
  • Portable pumps to restore operation of a damaged lift station following an event as back up

Head works

  • Nonelectrical backup controls where possible (e.g., float switches for pumps)
  • Mechanical screens up gradation to prevent debris blockages and hydraulic restrictions in anticipation of higher than normal sand, grit, trash and debris
  • Waterproof or elevate motor control units, instrumentation and controls, electrical panels
  • Replace dry well pumps with submersible pumps; consider increased capacity needed during flood events
  • Secure backup power supply for the head works

Waste water treatment plants

  • Secure air tanks to prevent floatation if flooded
  • Elevate, relocate or cap individual assets (e.g., blowers, chemical/fuel/air tanks, instrumentation/controls)
  • Have an alternative access plan in case normal access to the treatment plant is blocked
  • External connection to the facility's compressed air system to allow a temporary, portable air compressor to be used if the main air compressor becomes disabled

Electrical controls and supply

  • Waterproof electrical components (e.g., pump motors) and circuitry
  • Replace motorized and electrical equipment with submersible equipment (e.g., submersible pumps)

Waste Disposal Sites

Overall site

  • Temporary flood barriers (e.g., sandbags) for use in minor floods
  • Permanent physical barriers (e.g., flood walls, levees)
  • Green Infrastructure

Hazardous waste zone

  • Elevated dump area
  • Enclosed and water tight

Tourist Sites (Islands)

Waterfalls and hot water springs

  • Warning for flash floods
  • Safe Zones/ elevated escape areas in case of floods

Tourists trails

  • Elevated safety platforms
  • Flash floods warnings
  • Safe house on stilt for refuges



(1) Council of Australian Government's Senior Officers' Meeting Review of National CIP Arrangements, Final Report 2009


[1] http://www.weather-forecast.com/weather-stations/Hewanorra-International-Airport-1

 Last update: 01 - 01 - 2015