concept EIA-rapport - Staatsolie

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