Detailed visual seabed survey at drilling site 7218/11-1
Detailed visual seabed survey at drilling site 7218/11-1
Detailed visual seabed survey at drilling site 7218/11-1
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Table 6. Summaryof environmentalcosts and benefits associ<strong>at</strong>edwith the three main types of discharge<br />
scenarios.<br />
Scenario Cost Benefit<br />
Dischargeon sea floor<br />
directly<strong>at</strong> SPUD<strong>site</strong><br />
Discharge<strong>at</strong> seafloor to<br />
another loc<strong>at</strong>ion with<br />
lower spongedensity.<br />
5.4.2 Deposition scenarios rel<strong>at</strong>ed to area of impact to sponges<br />
SINTEFhave previously modelled likely sp<strong>at</strong>ial extent of depositions of <strong>drilling</strong> muds/cuttings,<br />
specified in terms of depositionthicknesses. We havethen compiledthe biologicalobserv<strong>at</strong>ionsof<br />
spongeabundanceswithin eachof the modelled areasof deposition.On this basis,we present an<br />
estim<strong>at</strong>e of area of affected seafloor containing the various c<strong>at</strong>egoriesof sponge abundances<br />
(Section5.4.3, Table7). TheRENASapplic<strong>at</strong>ionfor permit to oper<strong>at</strong>epresentsdifferent altern<strong>at</strong>ives<br />
for handlingof cuttingsreferred to asCase1 – 7. Thedischargescenariospresentedbelow refer to<br />
thesecases.<br />
Note: the dischargescenarioswere workedout usingthe originalSPUDloc<strong>at</strong>ion;but on 21.09.2012,<br />
Case7 wasupd<strong>at</strong>edto a new loc<strong>at</strong>ion.Thepositionsareasfollows(both usingED50Zone34N):<br />
Longitude L<strong>at</strong>itude<br />
Explor<strong>at</strong>ionWell -original 4<strong>11</strong>870 8001215<br />
Explor<strong>at</strong>ionWell - new 4<strong>11</strong>923 8001225<br />
1 CO2 emissionsare seenin the context of beinga major contributor to oceanacidific<strong>at</strong>ionthrough uptaketo<br />
the seafrom air.<br />
Short- to middle-term local mortality to<br />
spongeswithin anareaof between20 – 70 km 2<br />
(dependingon mortality to different particle<br />
sizefractions)<br />
Additional energy consumption (CO 2<br />
emissions 1 ) from vesselsin oper<strong>at</strong>ion using<br />
dynamicpositioning(DP). Averageof 30 m 3 fuel<br />
consumption per day per vessel is not<br />
unrealistic (pers. comm. Captain of Njord<br />
Viking).<br />
Physical damage to sea floor/sponges by<br />
pipeline.<br />
Localimpactsto another areahinderingfuture<br />
(short-to-middle-term) sponge recruitment <strong>at</strong><br />
this loc<strong>at</strong>ion<br />
Dischargefrom rig Additionalenergycosts(seeabove)<br />
Sediment<strong>at</strong>ionpotentially spreadover a wider<br />
area.<br />
Without d<strong>at</strong>a on lethal limits for<br />
exposure to sediment<strong>at</strong>ion, no<br />
guaranteedischargesare abovelethal<br />
limits.<br />
If not, riskof moreextensiveimpacts.<br />
Impact strictly localised.<br />
Minimalhabit<strong>at</strong> fragment<strong>at</strong>ion<br />
Long-term local recolonis<strong>at</strong>ion<br />
is likely (e.g. within the lifetime<br />
of the project– 30years+)<br />
Spongesdirectly <strong>at</strong> the SPUD<br />
<strong>site</strong>minimallyimpacted.<br />
Lower intensity of impacts<br />
immedi<strong>at</strong>ely around the SPUD<br />
loc<strong>at</strong>ion.<br />
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