MEDWAY COUNCIL COMAH OFF-SITE EMERGENCY PLAN ...

More documents

Recommendations

Info

ABRIDGED - Medway Council Off-site Emergency Plan – National Grid Grain LNG Ltd. In Stay In and Tune In, in line with COMAH regulations. This is considered to be the safest option in most hazard scenarios. 13.3 Access to and egress from Grain village may be restricted if the A228/B2001 alongside the National Grid Grain LNG site is impassable, resulting in the temporary displacement of people. This scenario is considered unlikely according to hazard information provided by National Grid Grain LNG, for more than 4 hours. There are 5 hazard scenarios with off-site implications that have the potential to result in a closure of the A228/B2001. 13.4 If the A228/B2001 was closed for a longer period due to a persistent hazard or damage to its structure it may became necessary to consider the use of other methods of access/egress. These options include the use of maritime transport and the air ambulance. Response decisions will be made dependant on the scale, nature and location of the incident. 13.5 Medway Council has procedures to manage nominated Emergency Assistance Centres that can provide shelter for those people who, as the result of an incident, are temporarily displaced and transport for those who may need evacuation to a place of safety. 13.6 Several sites have been predesignated in this plan and Medway Council Emergency Assistance Centre Guideline contains these and other site options, dependent on the emergency scenario. 14. Vulnerable People 14.1 Medway Council, Kent NHS and other appropriate organisations will share key information to assist in the pre-identification of vulnerable people using existing datasets and protocols and, where appropriate, consider evacuating those individuals/groups. 15. Environmental Impact (extract from National Grid Grain LNG’s COMAH Safety Report) 15.1 The dangerous substances stored on site, which bring about the requirement for a safety case report, are non-toxic. It is therefore considered that the main potential major accident hazards to the environment, as defined by the COMAH Regulations, are from fires. The two relevant hazards, from flammable gas clouds or from sustained levels of thermal radiation, are discussed below. Explosions are not considered here, as the consequences of explosions are unlikely to extend beyond the site boundary. 15.2 Either a flammable gas cloud or thermal radiation could cause damage off-site. However these scenarios are considered to be extremely unlikely, with the highest frequency being that for a severe earthquake which would in itself cause widespread devastation to the surrounding area. The hazard would depend on a variety of factors including the release event, wind direction, weather conditions and sometimes release orientation. The key potential accident hazards to the environment are assessed in the following sections. June 2011 Page 32 of 52
ABRIDGED - Medway Council Off-site Emergency Plan – National Grid Grain LNG Ltd. 15.3 It is universally agreed that it is difficult to predict the effect of fire on an ecosystem, because of the problems of understanding fire processes and ecosystem responses. Variables that affect fires include moisture levels, fuel load and arrangement, prevailing weather conditions, wind and topography. Given the fact that every fire is unique it is conceivable that a major accident could be caused by some of the incidents described below. However, deciding whether a fire had resulted in a Major Accident to the Environment (MATTE) would only be possible after detailed studies of the effects of the fire. 15.4 Flammable Gas Cloud – A flash fire is unlikely to have significant effect on the vegetation present on the Medway or Thames Marshes Ramsar, SPA and SSSI Sites or Grain Pit. 15.4.1 To constitute a MATTE, greater than 0.5 ha must be adversely affected, or greater than 10% of the area of the site affected (whichever is the greater), or greater than 10% of a particular habitat or population of individual species. Although approximately 5 ha of marshland is at risk from some damage, any damage caused by a flash fire would be expected to be very minor with all the species affected recovering rapidly. Similarly, whilst greater than 10% of Grain Pit could be affected by a flash fire, damage would be expected to be very minor with all the species affected recovering rapidly. All the types of vegetation present on the marshland, reed beds, scrubland or grassland around the site are expected to grow back in a short time. 15.4.2 For common flora and fauna present, a MATTE would be caused if 1% of any species were damaged, or 5% of any plant species. In addition to common species there are a number of protected species present around the LNG site. The MATTE thresholds for such species may be lower than 1% or 5%, and liaison with the appropriate statutory conservation organisation would be necessary to determine the appropriate threshold. Adult birds, reptiles, invertebrates and mammals that could be affected by flash fires are generally mobile and may be able to avoid the effects of a flash fire. However, the young would be more at risk. Following an incident, an investigation of the effects of the fires and consultation with the appropriate statutory conservation organisation would determine whether a MATTE had occurred. 15.4.3 Fire can have a wide range of effects on soil, depending on factors such as fire intensity and severity, soil moisture levels, soil composition and climatic regime. To constitute a MATTE the biological quality of soil must deteriorate such that common organisms are absent, the structure of the biological community is altered for periods in excess of a season, or normal ecosystem function is severely impaired for a period in excess of one year. It is not considered possible that a flash fire would have this great an effect. 15.4.4 There are three Grade 1 listed buildings and three SAMS within 3 km of the site. A flash fire would not be sufficiently fierce to cause damage to these buildings and structures, and therefore a flash fire arising from the LNG terminal is unlikely. 15.5 Thermal Radiation - Two thermal radiation hazard criteria are identified: Escape distance and Secondary Fires distance. Escape distance is defined as ‘the distance from a fire from which able bodied persons can be expected to escape June 2011 Page 33 of 52
Page 1 and 2: ABRIDGED - Medway Council Off-site
Page 13 and 14: 3.6.1 National Grid Grain LNG - Loc
Page 23 and 24: 6.6 National Grid LNG - Public Info
Page 31: ABRIDGED - Medway Council Off-site

MEDWAY COUNCIL COMAH OFF-SITE EMERGENCY PLAN ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?