concept EIA-rapport - Staatsolie

SRK Consulting: Project No: 439414 Staatsolie Pipeline EIA – Draft EIA Report Page 71
Probability of an incident
Generally, the main causes of pipeline failures, though rare, are:
• Damage from anchors, vessels or dropped objects (offshore pipelines);
• Third party interference (e.g. digging or driving stakes into the ground) (terrestrial pipelines);
• Material defect;
• Mechanical failure (e.g. excess pressure in the pipeline, splitting weld or stress on the steel);
• Natural hazards (e.g. flooding, landslides, earthquakes and sinkholes); and
• Operator error or malfunction of the pressure control and protection systems.
The risk of a pipeline incident is generally highest for the land-based portions of the pipelines and the
areas where the underground pipeline lies shallowest near the drill entry and exit points, as these
sections are more exposed. The risk of a pipeline failure through third party interference / external
damage decreases rapidly with the increasing depth of the pipeline underground. Natural hazards
are considered a relatively unlikely risk in Suriname, as the geology is considered very stable. Risk
stemming from operator error or malfunction can be minimised through the use of backup systems.
Impact if the incident occurs
The accidental release of large volumes of fuel from the pipeline could have a number of potential
impacts:
• Pollution of groundwater;
• Pollution of the Suriname River and terrestrial areas;
• Health hazard to people exposed to the leaked fuel; and
• Fire due to the ignition of the fuel.
Pollution of groundwater
As indicated in the section above, the soil profile along the pipeline corridor appears to consist
predominantly of clay, with intermittent silt and sand content, found most commonly at depth of 20 to
30 m. The water contained in these sand bodies exhibits a negative hydraulic pressure 36 , which
appears to illustrate both the embedded character of the sand body and the impermeability of the
surrounding clay. The pipeline may cross some of these sand bodies, in which case the negative
pressure is likely to be neutralized by allowing the inflow of additional groundwater. Should a pipeline
leak in this or a nearby section, any leaked hydrocarbons will enter the sand body, but are unlikely to
move far from the leak due to the absence of groundwater flow. The spread of pollutants is only
possible through diffusion, which is a very slow process, and the contamination will remain localized.
In places where the pipelines lie within or very close to the Zanderij aquifer, a leak would cause only
localised contamination of the aquifer, because groundwater flow is virtually absent (as there is no
extraction) and diffusion is slow, coupled with a tendency for the hydrocarbons to move upwards.
The water in the Zanderij aquifer is brackish in the study area and not used for drinking water.
Contamination of deeper-lying aquifers that do provide drinking water is not considered plausible
because of the thickness of the Zanderij aquifer and the presence of a clay layer between aquifers 37 .
36 The water pressure is lower than in the surrounding environment and so has a tendency to remain in situ rather than flow.
37 Some diffusion from the Zanderij to the Coesewijne aquifer is shown by Groen, but this is a very slow process.
REUT/DALC 439414_StaatsoliePipelineEIA_Draft EIA Report_Final June 2012