Managing Flood Risk During Construction

Flooding, heavy rainfall and extreme weather events continue to make the headlines, causing extensive damage to property and interrupting our daily lives.

What are the implications if your construction project is flooded?

How do you manage and mitigate the risk?

Flood risk

Flood events are one of the largest causes of physical loss, damage and delay during the construction phase of a project with consequential loss of revenue and potential financial penalties. Flood risk can affect all stakeholders, including clients, designers, consultants, contractors, insurers and third parties.

Many aspects of the construction project can be impacted by a flood, including partly constructed assets, temporary works, stored materials and plant & equipment. Where flood risks exist, it is critical these exposures are clearly identified, and mitigation measures implemented as part of the project development and delivery.

Typical flood exposures

During the construction phase of a project, assets can be more vulnerable to damage, depending on the stage of the works:

• Groundworks

  Excavations, foundations and earthworks can become unstable when saturated, while underground works are at significant risk of flood water ingress and damage due to the effect of water pooling and finding its way to the lowest point(s) of the site.

• Temporary and incomplete works

  Temporary works are often because of their very nature built and maintained to lower standards than permanent works, making them more susceptible to flooding risks. Partially completed structures can also allow significant water ingress into the building, while incomplete pipe connections, drainage arrangements and unplugged penetrations can divert water to lower-level surface areas vulnerable to flood risk, resulting in consequential damage and losses.

• Materials, plant and equipment storage

  Materials, plant and equipment stored at ground or below ground level are particularly vulnerable to flood water damage. Even large and heavy plant or materials have the potential to float in flowing water and cause further damage to surrounding assets. Water damaged plant and equipment may also become non-compliant with quality specifications and breach warranties.

• Indirect consequences

  Damage to public utilities and flooding of local roads can affect access and the supply to site, while surge in demand for third party specialist contractors and supplies post-flood, including clean-up services, emergency generators, water pumps and dehumidifiers, can result in indirect losses.

• Third party exposure

  Where flood waters are diverted and/or collected on site, there is a risk that containment systems such as trenches, culverts and attenuation tanks etc. can be overwhelmed, placing third parties at increased risk of flood damage, where originally there was limited or no flood exposure. This could lead to physical damage to third party property, business interruption and potentially life-threatening events.

Vulnerabilities

Vulnerabilities can also occur as a result of changes in the use of land, topography or infrastructure, disrupting natural drainage and soakaway times or changing flood flow routes. Project design that allows insufficient drainage capacity can also result in flood water being directed to project premises.

Assessing flood risk

Flood risk assessment and management should be undertaken throughout the whole life cycle of a project.

Projects most vulnerable to flood risk are those closest to a water source, situated within a flood plain, or where there is the potential for high groundwater infiltration or high rainfall. The topography of the site and its surrounding areas can also affect water flow pathways, with elevation, direction and degree of sloping land impacting the speed of spread, velocity, depth and duration of flood water.

Most projects that present an increased flood risk will have a flood risk assessment as part of the planning application process. This provides a useful source of information but does not specifically address flood risks during the construction phase.

Even where there is no perceived additional flood risk from a planning aspect, there remains a risk for all construction sites from flooding events such as surface water run off and extreme rainfall.

Flood Risk Management Plan

The Flood Risk Management Plan should be appropriate for the project and should include all identified flood risks, mitigation measures and emergency procedures established for the project. It should include roles and responsibilities, lines of communication, flood risk assessments, flood hazards, flood risk registers, design principles and mitigation measures, weather forecasts, emergency procedures and check sheets.

• Flood Risk Management Plans should consider:
• Design of permanent works in respect of materials, location, elevation etc.
• Temporary works flood protection and mitigation.
• Flood risk management infrastructure incorporated in the permanent works.
• Elevation or protection of sensitive equipment.
• Appropriate sequencing of the permanent works construction
• Provision for storage of construction materials and equipment
• The response in relation to forecast high rainfall or imminent flood events

It’s also strongly recommended that you engage early on with your insurance brokers and insurers ensuring that flood risk information is provided at the earliest opportunity.

At PIB, we are acutely aware of the need for forward planning to counteract the impact of flood risks to construction projects, with insurance being a vital component of the mitigation package, along with flood risk assessment and management.

We have an in-depth understanding of the nature of flood risk in relation to construction projects and work with specialist insurers and suppliers to ensure the interests of all your stakeholders are protected.