❓ Question regarding a significant caustic slurry spill at Alcoa's Wagerup refinery, seeking details on the DMIRS investigation, spill volume, chemical composition, and enforcement actions. The answer provides preliminary findings, volume estimates, and enforcement actions taken, but notes the investigation is ongoing.
AnsweredQoN 275Legislative Council
QuestionView source ↗
I
refer to the spill of caustic slurry at Alcoa's Wagerup refinery in March
2021, and subsequent reports indicating that an investigation would be
undertaken by the Department of Mines, Industry Regulation and Safety
(DMIRS), and I ask: (a) what
were the primary findings of DMIRS’s investigation into the spill: (i) will the Minister table the investigation's findings; (ii) if no to (a)(i), will the
investigation's findings be made publicly available; and (iii) if no to (a)(ii), why not; (b) what did the
investigation find as the root cause of this spill; (c) what
is the estimated volume of material spilled during the incident: (i) was the spill
contained within the bund underneath the tank; (ii) how much material was spilled beyond the
bund underneath the impacted tank; and (iii) how far did the spill
travel beyond the bund underneath the impacted tank; (d) what was the
predominant chemical composition of the material spilled; (e) what enforcement and
compliance actions have been or will be taken as a result of the spill; and (f) if the questions
above cannot be answered due to DMIRS’s investigation still being in progress,
when will the investigation be complete?
refer to the spill of caustic slurry at Alcoa's Wagerup refinery in March
2021, and subsequent reports indicating that an investigation would be
undertaken by the Department of Mines, Industry Regulation and Safety
(DMIRS), and I ask: (a) what
were the primary findings of DMIRS’s investigation into the spill: (i) will the Minister table the investigation's findings; (ii) if no to (a)(i), will the
investigation's findings be made publicly available; and (iii) if no to (a)(ii), why not; (b) what did the
investigation find as the root cause of this spill; (c) what
is the estimated volume of material spilled during the incident: (i) was the spill
contained within the bund underneath the tank; (ii) how much material was spilled beyond the
bund underneath the impacted tank; and (iii) how far did the spill
travel beyond the bund underneath the impacted tank; (d) what was the
predominant chemical composition of the material spilled; (e) what enforcement and
compliance actions have been or will be taken as a result of the spill; and (f) if the questions
above cannot be answered due to DMIRS’s investigation still being in progress,
when will the investigation be complete?
AnswerView source ↗
Answered
12 October 2021
Responded by
Minister for Regional Development representing the Minister for Mines and Petroleum
Response time
9 days
(a) – (f)
An initial investigation found that a mud washer vessel had a major loss of containment. During attempts to restart the rake arm drives that had stalled after a process disruption, a rake arm suffered a mechanical failure inside the vessel, causing a section of the rake arm to puncture the steel flooring, creating a hole. Investigations are ongoing and additional causes may be identified as the investigation progresses.
The estimated volume of material, a process solution containing sodium hydroxide (caustic) and mud slurry, spilled during the incident was over seven million litres. Approximately two million litres was contained within the bund underneath the tank. Approximately five million litres overflowed into surrounding catchment areas. Of this, approximately 709 kilolitres went to unsealed ground beyond tertiary catchment areas. The spill remained within the operational footprint of the Alcoa Wagerup Alumina Refinery.
One improvement notice was issued by the Mines Safety Directorate and two remediation notices were issued by the Dangerous Goods Directorate of DMIRS for identified breaches under the Mines Safety and Inspection Act 1994 and the Dangerous Goods Safety Act 2004 , respectively.
DMIRS investigation findings are not generally tabled, as information in relation to completed investigations may be released via approved valid applications made to DMIRS pursuant to Section 11 of the Freedom of Information Act 1992 .
An initial investigation found that a mud washer vessel had a major loss of containment. During attempts to restart the rake arm drives that had stalled after a process disruption, a rake arm suffered a mechanical failure inside the vessel, causing a section of the rake arm to puncture the steel flooring, creating a hole. Investigations are ongoing and additional causes may be identified as the investigation progresses.
The estimated volume of material, a process solution containing sodium hydroxide (caustic) and mud slurry, spilled during the incident was over seven million litres. Approximately two million litres was contained within the bund underneath the tank. Approximately five million litres overflowed into surrounding catchment areas. Of this, approximately 709 kilolitres went to unsealed ground beyond tertiary catchment areas. The spill remained within the operational footprint of the Alcoa Wagerup Alumina Refinery.
One improvement notice was issued by the Mines Safety Directorate and two remediation notices were issued by the Dangerous Goods Directorate of DMIRS for identified breaches under the Mines Safety and Inspection Act 1994 and the Dangerous Goods Safety Act 2004 , respectively.
DMIRS investigation findings are not generally tabled, as information in relation to completed investigations may be released via approved valid applications made to DMIRS pursuant to Section 11 of the Freedom of Information Act 1992 .
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