Southwest Environmental Limited

Fire Water Management Plan

A fire water management plan is a document which contains a series of measures to limit the damage caused by fire water. Fire water is the water used to extinguish a fire (non-routine) that may run off site and cause damage to neighboring properties or the natural environment.

Fire Water is potentially very damaging, it can contain all sorts of chemicals, which originate from the fire (combustion products and partially combusted materials) and anything that may be stored on site ordinarily such as oils or chemicals.

Under normal circumstances these substances would be safely stored, however during a fire containment may fail, and with the help of water used in fighting the fire they may be washed off site. Another problem is when fire water soaks in to the ground where it can contaminate groundwater.

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PPG 18 Managing Fire Water and Major Spillages Containment Systems for the Prevention of Pollution (C736) Fire Water Containment Tanks Earth Banked Fire Water Containment

PPG 18 Managing Fire Water and Major Spillages

Largely superseded, but still relevant in some cases. Intended to assist in the identification of the equipment and techniques available to prevent and mitigate damage to the water environment caused by fires and major spillages.

Pollutants may escape from the site into the water environment by a number of pathways. These include:-

i. the site ’ s surface water drainage system, either directly or via off-site surface water sewers.
ii. direct run-off into nearby watercourses or onto ground, with potential risk to ground waters.
iii. via the foul drainage system, with pollutants either passing unaltered through a sewage treatment works or affecting the performance of the works, resulting in further environmental damage.
iv. through atmospheric deposition, such as vapour plumes. The information in this guidance note is based on CIRIA (Construction Industry Research and Information Association) Report 164 (Reference 3) (Superseded by C736 Below) , which contains detailed information on hazard identification, risk assessment and secondary containment systems.

On any site there may be one or more levels of containment. In deciding the appropriate level of containment a risk assessment will be helpful. The operator should consider the hazardous materials on site, the risks posed by accidents, fire, flooding and vandalism, likely failure mode of the primary containment, the sensitivity of the receiving environment and the importance of preventing any resultant discharge to it.

Containment Systems for the Prevention of Pollution (C736)

This guidance has been developed to assist owners and operators of industrial and commercial facilities storing substances (inventories) that may be hazardous to the environment. It provides guidance on identifying the hazards, assessing the risks and mitigating the potential consequences of a failure of the primary storage facility and/or the combustion of its contents. A three-tier risk assessment methodology is introduced with recommendations for different ‘classes’ of construction for each.

In regards to this standard Southwest Environmental Limited are typically commissioned to:

The above are actioned based on the source pathway receptor model. Sources and release volumes are calculated as worst case drawing on case studies and sector guidance.

Fire Water Containment Tanks

The type of fire water containment tank you use will depend largely on the type of site we are looking in to. On typical flat sites an over ground tank with a pumped sump, is the quickest option to implement.

On sites with slope it is sometime possible to provide an above ground fire water containment tank (as per image), with a gravity fed inlet. But this is often not possible.

Earth Banked Fire Water Containment

Perhaps the most popular containment system is an earth banked fire water containment system. These may seem like a cheap and easy option, but their effacy relies heavily upon on site soils types. A gravel bund will not work, even some clays are unsuitable if the coarse fraction is over a certain percentage. Earth bunds should be designed in line with BS EN 1997-1:2004, this includes provision for geotechnical design by competent persons.

Fire Water Transfer Systems

A transfer system, transfers fire water from the area upon it is likely to be used to a tank or banked area, or both. This can be achieved via:

All of these features need to be carefully considered and often used in combination so as to deal with initial surge events and subsequent "trickle" events. Much of this infrastructure will never be used, remaining in suit for many years as such it needs to include features to deal with long terms problems such as subsidence.