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Product and extinguishing water retention in the event of plant incidents

For companies that handle hazardous substances, it is the worst case scenario: If an operational disruption results in the uncontrolled release of large quantities of hazardous substances, there is a risk of serious consequences for people and the environment. In particular, the case of fire, where the fire brigade's extinguishing water comes into contact with hazardous operating materials, is a typical risk that plant operators have to reckon with and take precautions for. In the following, we look at typical accident scenarios that can also affect your company. We provide an overview of your legal obligations as an operator and present the appropriate solutions for product and extinguishing water retention.

Stop the spread at an early stage - prevent serious damage

Although responsible companies give top priority to the issues of safety and environmental protection, damage events from the past show: Despite extensive safety precautions, operational disruptions can never be completely ruled out. Unfortunately, it happens time and again that, for example, contaminated extinguishing water from fires gets into surrounding waters and causes massive damage. The consequences are borne not only by the environment and the animal population, but also by employees and people in the neighbourhood. If, for example, the groundwater is affected by contamination, there is sometimes a risk of serious damage to the health of local residents. In order to decisively limit the extent of damage in the event of operational disruptions, measures for product and extinguishing water retention are of great importance. They do not prevent the operational disruption itself - but they effectively help to stop the spread of hazardous liquids at an early stage and prevent them from spreading uncontrollably into surrounding areas, soils and water bodies.

General operator obligations and possible plant incidents that you should keep in mind

In preparation for a possible plant incidents, plant operators are obliged to take precautions to prevent hazardous substances from escaping into the environment as far as possible. It is a basic requirement that facilities must be planned, constructed and operated in such a way that in the event of an incident, mixtures that may contain leaked substances hazardous to water are retained. In addition, operators must implement preventive measures to keep the effects of plant incidents as low as possible: If, in the event of an incident, it cannot be ruled out that substances hazardous to water will escape from parts of the installation, the operator must immediately take measures to limit the damage.

In connection with the leakage of water-polluting liquids, companies usually have to deal either with major product leaks from plants or with fire incidents where, for example, contaminated extinguishing water has to be retained.

When identifying possible sources of danger, the following reasons in particular should be taken into account:

  • Plant-related sources of danger

  • Environmental sources of danger, such as earthquakes or floods

  • Tampering by unauthorised persons

Scenario 1: Major product leakage from plants

Spills of large quantities of hazardous substances can have a variety of causes. There is a long list of damage events and operational malfunctions in local industrial plants. Critical accident blackspots are, for example, pipelines in which liquids hazardous to water are conveyed. Here are some examples of frequently identified causes of accidents:

  • Damage due to collision with operating vehicles

  • Unnoticed corrosion damage / material wear

  • Operating errors

  • Malfunctions in the process control system

  • Storm damage

If, in the event of a corresponding plant incident, it cannot be ruled out that substances hazardous to water will escape from parts of the plant, the operator is legally obliged to take immediate measures to limit the damage.

Case study: Toluene release in Cologne

A truck-mounted crane hit a toluene loading pipeline. The pipeline was damaged and toluene leaked into the ground. The detailed causes and the sequence of events are being investigated by a recognised expert as part of a safety inspection.

Case study: Crude oil release in Gelsenkirchen

A crude oil leak (approx. 2,100 kg) occurred due to internal corrosion in a pipe system with no flow - a so-called dead branch. The location of the leak was in the circulation pipe of a storage tank. The circulation pump was immediately shut down and the leaked product was taken up as far as possible by means of a suction truck. The contaminated soil was removed (90-100 m3) and disposed of properly. The groundwater was not contaminated by the leaked product.

Case study: Zinc sulphate release in Duisburg

A worker wanted to clear a blocked pipeline between the tank and the pump. To do so, he closed a hand valve on the tank (capacity 15,000 l) and opened the pipeline in front of the pump. Apparently, the hand valve was not completely closed, so that after unblocking the pipe, the zinc sulphate raw solution (approx. 15 % Zn) leaked out of the tank. The employee opened the drain valve of the container and emptied it into the catch basin. However, part of the solution ran into the raw materials hall via the open pipe in front of the pump. Despite the company's containment measures, about 500 l ran over the western gate onto the open area in front of the hall. From there, it entered the 6-chamber basin via the company's sewer system. All surrounding sewer inlets were immediately closed with sewer covers. However, one sewer inlet was blocked with a pallet. When this was discovered, the outlet of the 6-chamber basin towards the sewer system was immediately closed. It cannot be ruled out that Zn-contaminated wastewater entered the public sewer system via the 6-chamber basin. It is assumed that approx. 50 l of raw solution was released.

Source: North Rhine-Westphalia (Germany) State Agency for Nature, Environment and Consumer Protection

Scenario 2: Fire incident / contaminated extinguishing water

The retention of extinguishing water plays an important role in plant-related water protection. If the extinguishing water is contaminated with water-polluting production, auxiliary or operating materials in the event of a fire, it can cause considerable consequential damage as soon as it enters surrounding bodies of water or seeps into the ground. This potential danger is also particularly recognised by the legislator. Thus, it explicitly obliges operators of facilities for handling substances hazardous to water to take state-of-the-art measures to retain the contaminated extinguishing water in the event of a fire:

"Facilities must be planned, constructed and operated in such a way that substances hazardous to water, extinguishing, sprinkling and cooling water escaping in the event of fire incidents, as well as the resulting combustion products with properties hazardous to water, are retained in accordance with the generally recognised rules of technology".

Technical solutions for product and extinguishing water retention

There are various technical options for preventing the extinguishing water produced during firefighting or hazardous substances escaping from installations from spreading in an uncontrolled manner. A possible distinction between different containment facilities and systems can be made on the basis of their functionality:

Self-operating systems

Self-operating systems are stationary solutions in which product or extinguishing water retention is provided without the need to initiate additional triggering measures.

Constructional solutions, e.g.
Extinguishing water retention basins outside buildings into which the extinguishing water can flow without the use of pumps.
Use of the existing wastewater sewer system
Designing the floor area of storage buildings as a catchment area (by means of upstands, door thresholds, ramps and catchment channels).
Sufficiently dimensioned rainwater relief basins of the wastewater treatment plant, if dimensioning and rapid emptying allow this
Liquid-tight open storage areas and loading zones with a slope, which are secured against uncontrolled run-off towards the edge by a circumferential upstand.
Stowage volumes within the buildings (e.g. basement) and special collection rooms (in the case of flammable liquids, sufficient mechanical ventilation must be ensured).
Empty tanks with corresponding supply system without pumps

Non-automatic systems

Systems that are not automatically effective enable product or extinguishing water retention only after technical and/or organisational measures have been introduced. A distinction is made here between stationary and mobile variants, among others.

Stationary automatic systems, e.g.
Extinguishing water retention basins into which the extinguishing water is pumped by automatically controlled pumps in the event of a fire.
Automatically controlled extinguishing water barriers that are activated in the event of a fire by the detection of fire parameters, e.g. smoke or heat, and automatically move into the shut-off position.
Stationary manually triggered systems, e.g.
Manually triggered liquid barriers which are permanently installed in their holders and are moved into the shut-off position by manual triggering, i.e. by muscle power, stored energy (weight force, spring force) or auxiliary energy (e .g. electric, hydraulic, pneumatic).
Stationary liquid barriers to be used manually, which are inserted by hand into holders permanently installed for this purpose at the place of use.
Mobile systems, e.g.
Mobile liquid barriers, e.g. for filling with water
Drain seals
Mobile collection containers (leakage trays, leakage collection tarpaulins, etc.)
Sealing plugs

Equipment options for technical room systems

Mobile retention systems

Leakage cleaning

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The specialist information on this page has been compiled carefully and to the best of our knowledge and belief. Nevertheless, DENIOS AG cannot assume any warranty or liability of any kind, whether in contract, tort or otherwise, for the topicality, completeness and correctness either towards the reader or towards third parties. The use of the information and content for your own or third party purposes is therefore at your own risk. In any case, please observe the locally and currently applicable legislation.

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