concept EIA-rapport - Staatsolie

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SRK Consulting: Project No: 439414 Staatsolie Pipeline EIA – Draft EIA Report Page 72 With the implementation of mitigation measures listed below, the risks of substantial sub-surface contamination or aquifer contamination following a leak is considered minimal. Pollution of surface water and areas The risk of any spill reaching the surface is higher in areas where the pipeline lies above ground or shallow underground, as there is little or no overlying material that could prevent or slow the rise of fuel and exert counter pressure on the pipeline. However, shallow underground pipeline sections are expected to be specially protected by a plate inserted above them and thicker pipeline walls. The majority of the pipeline lies embedded in a clay layer up to 30 m underneath the Suriname River, and is further encased by the bentonite drilling mud that remains in the drill hole and congeals. The clay layer and congealed bentonite mud are relatively impermeable, and any leaks, particularly gasoline or diesel, would be expected to only slowly leak upwards through fissures in the ground. Leakage that occurs within a compact clay layer would thus be very localised 38 . These sections of the pipelines are also well protected from external interference, and the risk of an incident and/or the leaked material causing widespread pollution is lower. Based on the calculations undertaken in the QRA to evaluate pipeline risks, the maximum individual risk is low, i.e. generally well below 1x10 -6 per year risk of a fatality (meaning there is a one in a million chance of a fatality per year). The highest risk was calculated for the areas where pipeline sections HDD2 and HDD3 connect and the SOL and OGANE offtakes, where the fatality risk was calculated at a still very low 1.6x10 -6 per year. Based on international guidelines, this risk is considered to be acceptable without any further mitigation. The potential impact of an incident depends on the type of fuel that is spilled and the environment in which the spill occurs, as described in Table 6-12. Table 6-12: Potential impacts from pipeline leaks in various environments Product Location Suriname River LPG spill Diesel/gasoline spill An LPG spill is likely to reach the surface (river bed) more quickly, as the LPG is much lighter than its surrounding material. It is expected that an LPG incident in the Suriname River would have no long-term environmental damage as the gas evaporates rapidly with little or no impact to surroundings. The main hazard associated with the LPG pipeline is loss of containment resulting in a gas release, which could be ignited by a vessel in the vicinity. The resultant fire could engulf the vessel and cause fatalities to the crew and passengers on board, either directly due to the fire or due to the vessel sinking (in the worst case). A gasoline or diesel spill, if / once it has worked its way up from the pipeline, forms a layer on the water surface and therefore has a higher potential impact to the bio-physical environment than LPG. Diesel and gasoline will be transported with the river flow (ebb and flow conditions), with the influence of wind drag. Evaporation occurs immediately after release. As the surface slick spreads, more of the diesel and gasoline are exposed to the atmosphere, causing the evaporation rate to increase. Since gasoline is considerably more volatile, it would evaporate much more readily than diesel. Evaporation is the most significant physical-chemical process causing the reduction in the spill volume. Diesel and gasoline plumes may reach the riverbanks, with deposition along the shoreline, to be later re-entrained into the river current. Some of the suspended oil droplets may also sink to the riverbed. The oil deposited on the channel bottom may be transported laterally or resuspended, or undergo further biological or physical-chemical reaction. 38 As opposed to leakage within a sandy substrate, in which the fuel could easily spread over a large area before reaching the river, resulting in extensive sub-surface contamination REUT/DALC 439414_StaatsoliePipelineEIA_Draft EIA Report_Final June 2012
SRK Consulting: Project No: 439414 Staatsolie Pipeline EIA – Draft EIA Report Page 73 Product Location On land LPG spill Diesel/gasoline spill A full-bore LPG pipeline breach would result in a complex two-phase choked gas flow. The possibility of a significant flash fire resulting from delayed remote ignition is extremely low due to the buoyant nature of the vapour, which generally precludes the formation of a persistent flammable vapour cloud at ground level. The dominant hazard is thermal radiation from a sustained jet or trench fire, which may be preceded by a short-lived fireball. Spillage of gasoline and diesel could result in an unignited vapour cloud, pool fire or, in the case of gasoline, a delayed flash fire. The risk due to toxic cloud formation, either as an unignited cloud or a burning pool (jet fire) is low. As discussed above, the intensity of an impact would depend on the volume and type of pollutants released and the type of environment into which it is released. Particularly, a spill of diesel or gasoline in the Suriname River could cause an impact of regional extent through the dispersion of the fuel on the river, while the intensity of an impact from a jet fire could be high. In all cases, it is expected that the pollutant will disperses relatively quickly, particularly in the water, and that any terrestrial areas can be remediated. The potential impact from an accidental release of hydrocarbons due to a pipeline leakage or rupture is therefore assessed to be of medium significance (negative) without mitigation (Table 6-13). The implementation of the recommended mitigation measures would reduce the likelihood of an incident (which is not reflected in the rating below) and the extent and intensity of an impact by shortening the response time, thereby limiting the amount of fuel that is spilled before the leak can be stopped. The overall significance of the impact, should it occur, reduces to very low (negative) after mitigation. Table 6-13: Significance of accidental release of hydrocarbons from the pipeline – Operation Extent Intensity Duration Consequence Probability Significance Status Confidence Without mitigation Regional 2 High 3 Short-term 1 Medium 6 Probable MEDIUM -ve Medium Essential mitigation measures: To reduce the probability of an incident (does not affect significance rating): • Design the pipelines to minimise the risk of failure (including coating and weld inspection) • Regularly monitor and maintain the pipelines through smart pigging to prevent failures. • Install a cathodic protection system and maintain in good order. • Regularly inspect the pipeline corridor to detect anything that could damage the pipeline. To reduce the impact in the event of an incident: • Avoid drilling through sand bodies, as far as possible. • Maximise the vertical distance between pipelines and the Zanderij aquifer (aim for 10 m or more). • Maintain a minimum distance of 200 m from drinking water wells along the pipeline route. • Aim to leave a layer of bentonite in the drill hole to act as further sealant for the pipeline. • Monitor and compare product volumes entering and exiting the pipelines for indications of lost product. • Ensure adequate spill response measures are included in the Emergency Response Plan. • Notify MAS and adjacent landowners immediately in the event of a spill. • Ensure adequate spill containment and response equipment are available, including oil booms and oil spill dispersants. • Ensure all relevant staff are trained in the requirements of the Emergency Response Plan and in the use of spill containment and response equipment. With mitigation Local 1 Medium 2 Short-term 1 Very low 4 Probable VERY LOW -ve Medium REUT/DALC 439414_StaatsoliePipelineEIA_Draft EIA Report_Final June 2012
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1 INLEIDING NIET‐TECHNISCHE SAMEN
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