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Environmental Statement - Maersk Oil

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B ‐ 2<br />

Halocarbon release<br />

during emergency<br />

events<br />

Discharges to Sea Deliberate discharges<br />

from drilling<br />

operations<br />

Contained and<br />

treated drilling fluids<br />

Contained and<br />

treated drainage<br />

water<br />

Liquid waste<br />

(domestic sewage)<br />

Fire fighting systems can be<br />

designed to release harmful<br />

halocarbons<br />

WBM and cuttings, brine,<br />

cementing chemicals & clean<br />

up chemicals all required in<br />

the drilling process<br />

Rotomill treated OBMs, OBM<br />

contaminated brine spacer,<br />

cuttings & cleaning chemicals.<br />

Other oily slops.<br />

Open drains collect spills &<br />

drainage water from all<br />

hazardous areas on the rig.<br />

These drains feed into the<br />

drainage cassion which<br />

provides oil & water<br />

separation.<br />

Discharge of sewage (grey &<br />

black water macerated to <<br />

6mm prior to discharge via a<br />

sewage caisson).<br />

2 1 Low<br />

Halons cause depletion in the upper atmosphere and are<br />

regarded as greenhouse gases<br />

Likelihood Consequence Risk<br />

2 1 Low<br />

Short term impact on water quality and localised smothering<br />

of seabed and associated biota<br />

Likelihood Consequence Risk<br />

5 2 Moderate<br />

Release of untreated OBM’s can result in toxic or sub‐lethal<br />

effects on sensitive organisms and ecosystems.<br />

Bioaccumulation of heavy metals in marine organisms. Burial<br />

of benthic organisms/ modification to the benthic<br />

environment.<br />

Likelihood Consequence Risk<br />

5 1 Low<br />

Uncontrolled discharge of oil in water can result in narcotic,<br />

toxic, teratogenic impacts and localised water column<br />

enrichment etc.<br />

Likelihood Consequence Risk<br />

2 2 Low<br />

Sewage and food waste has a high BOD resulting from organic<br />

& other nutrient matter in the detergents & human wastes<br />

that can impair water quality in the immediate vicinity of the<br />

discharge.<br />

Likelihood Consequence Risk<br />

Balloch Field Development <strong>Environmental</strong> <strong>Statement</strong><br />

Drilling rig contractors are phasing<br />

out halons in compliance with<br />

legal requirements.<br />

Halocarbons will only be used in<br />

the event of a fire.<br />

Maximum efficient use of WBM.<br />

Brine contaminated with oil to be<br />

shipped to shore for treatment<br />

and disposal<br />

Use of PLONAR chemicals (i.e. low<br />

toxicity chemicals).<br />

All OBM’s will be processed using<br />

Rotomill % of oil on cuttings<br />

discharged < 0.1%<br />

MARPOL compliant filtration and<br />

monitoring equipment with<br />

discharges of oil in water at less<br />

than 15ppm.<br />

Tanks and machinery spaces are<br />

fitted with bunding to collect<br />

spillages and waste.<br />

Drains are plugged on NTVL.<br />

Sewage treatment unit on board<br />

rig (MARPOL) and vessels to<br />

reduce BOD prior to discharge,<br />

this will aid biological breakdown<br />

on release.<br />

Appendix B ‐ <strong>Environmental</strong> Assessment<br />

None envisaged as the<br />

development should not<br />

lead to any releases.<br />

Negligible impact.<br />

Minimal discharge of<br />

WBM to sea with only<br />

localised temporary<br />

effects on the water<br />

column and seabed. Low<br />

impact.<br />

No detectable increase in<br />

the water column or<br />

sediments of any the<br />

OBM drilling fluids or<br />

chemicals discharged.<br />

Low impact.<br />

Good working practice<br />

will minimise any<br />

potential spillage.<br />

Negligible impact.<br />

Negligible impact.

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