Environmental Statement - Maersk Oil

5‐ 14
Balloch Field Development Environmental Statement
Section 5 Assessment of Potential Impacts and Controls
When PW is discharged there is expected to be an immediate 30 ‐ 100 fold dilution, with a
subsequent dilution of at least 1,000 by 500 m from the discharge point (OGP, 2005). Given the water
depth and prevailing currents, PW will rapidly dilute. Any impact on water quality will be confined to
the immediate vicinity of the discharge point, with levels of contaminants rapidly returning to
background levels.
Oil discharged with produced water
In order to calculate the maximum weight of oil discharged with the PW, a discharge quality in line
with regulatory requirements of 30 mg/l oil in water content was used. Table 5‐12 shows the
maximum dispersed oil associated with PW from the Balloch field. For the purpose of the assessment
it has been assumed, as a worst case, that all the PW from the Balloch development will be
discharged to sea and that the oil in water content will be at the maximum permitted level of 30 mg/l.
Typical oil in water content of PW discharged from GPIII since 2006 has been