Environmental risk assessments should be carried out using the CDOIF guidance.
The COMAH Competent Authority considers the CDOIF (Chemical and Downstream Oil Industries Forum) guidance document 'Environmental Risk Tolerability for COMAH Establishments' to be a benchmark standard and expects that COMAH sites (Upper Tier and Lower Tier) consider the CDOIF guidance when carrying out or reviewing their environmental risk assessments.
Previous guidance on the tolerability of Major Accidents to the Environment (MATTE) was overly conservative as there was only one level of MATTE, with very low tolerability levels that could be difficult to achieve. The new guidance now sub-divides MATTEs into four levels, A to D, depending on the extent and severity of the incident combined with the duration of harm. Each of these four consequence levels has different tolerability boundaries; two levels are below the single MATTE boundaries from the old guidance.
Although the guidance may seem lengthy and onerous, it could provide financial benefits to many sites due to the more realistic tolerability boundaries that reflect a lower environmental risk. A more accurate and proportionate ERA will result in better informed ALARP decisions; targeting financial resources more effectively, and avoiding unnecessary spend.
Here at C3, we are constantly improving our products and services to meet the needs of our clients and also of the regulators. We have already completed many ERAs using the CDOIF guidance and have also incorporated the guidance into our PHA tools; calibrating our environmental risk matrix against the CDOIF guidance. The CDOIF tolerability bands can then be used during a PHA and/or during any subsequent ALARP decisions. Investing in a CDOIF assessment by C3, before your PHA or ALARP demonstration, can in many cases lead to significant reductions in the size and cost of the subsequent improvement plan.
For any COMAH site, regardless of the substances stored, one of the most significant major accidents can be the release of firewater. The firewater can contain combustion products but can also contain significant amounts of unburnt substances, which can be harmful to people or the environment.
This can be particularly important for chemical warehouses, which often contain a diverse mixture of substances, some of which can be COMAH dangerous substances but also other ‘benign’ substances. Even if the warehouse does not contain flammable substances, there are usually lots of combustible materials present and the consequences of a warehouse fire must be considered, as there can be significant impacts to people from radiation or smoke, plus impacts to the environment from the firewater runoff.
The guidance document PPG 28 (Controlled Burn) considers situations where a controlled burn strategy could be used to restrict or avoid the application of firefighting media such as water. However, this strategy could have adverse impacts by allowing or increasing the formation of hazardous gaseous by-products. PPG 28 also states that the protection of people must always take precedence over environmental concerns; therefore a controlled burn may not be appropriate as the impact on people from the smoke plume can be far greater than the impact on the environment caused by contaminated firewater runoff.
C3 can help you to estimate the concentration of substances in the firewater and then help you to estimate the impacts and categorise any potential MATTE using the CDOIF guidance. We can also estimate the contents of a smoke plume, and model it’s dispersion to estimate the potential harm to people from the plume.
