Question On Notice No. 755 asked in the Legislative Council on 13 March 2018 by Hon Robin Chapple
Question Directed to the: Minister for Regional Development representing the Minister for Water
Parliament: 40 Session: 1
Question
(1) I refer to the management and facilities of the Broome South Wastewater Treatment Plant, and I ask:
(a) when was the treatment plant built;
(b) how many times has effluent and/or wastewater, treated or otherwise, overflowed since it was built;
(c) what were the dates of the overflows;
(d) are the treatment ponds connected to spillways;
(e) if yes to (d), could untreated sewage have overflowed into secondary and tertiary ponds and into Roebuck Bay;
(f) what were the rainfall figures for the overflow events;
(g) are there reports detailing the overflow events;
(h) if no to (g), why not;
(i) if yes to (g), will the Minister table all reports on overflow events;
(j) if no to (i), why not;
(k) will the Minister table all the sampling results; and
(l) if no to (k), why not?
(2) I refer to the recent widespread rainfall experienced in the North West of Western Australia and various news media reports describing overflow at the Broome South Wastewater Treatment Plant, and I ask:
(a) on which specific dates did the Broome South Wastewater Treatment Plant overflow in 2018;
(b) if (a) cannot be answered, why not;
(c) how long did it overflow for;
(d) if (c) cannot be answered, why not;
(e) was the overflow sampled for water quality;
(f) if no to (e), why not;
(g) what volume of overflow is estimated;
(h) if (g) cannot be answered, why not;
(i) how many kilograms of total nitrogen and total phosphorous are estimated to have flowed from the Broome South Wastewater Treatment Plant into Roebuck Bay in 2018;
(j) if (f) cannot be answered, why not; and
(k) what is the maximum capacity of rainfall the treatment plant can receive before overflow occurs?
(3) I refer to the Water Corporation, and ask:
(a) is the Water Corporation legally bound to contain wastewater during all rainfall events;
(b) if no to (a), why not; and
(c) if yes to (a), what is the maximum wastewater the Water Corporation is legally bound to contain during rainfall events?
Answered on 10 April 2018
(1a) 1981
(1b) Four
(1c) 30 January 1997; 5-6 March 2000; 30 to 31 January 2018; 17 to 18 February 2018
(1d) Yes
(1e) The overflows were all treated wastewater, which, after further dilution with stormwater running through the catchment would likely have egressed into Roebuck Bay.
(f) Data extracted from Bureau of Meteorology website:
• 30 January 1997 - 477mm within 24 hours
• 5-6 March 2000 - 158mm within 48 hours (after Broome had received more than its average yearly rainfall total in January and February)
• 30-31 January 2018 - 498mm within 48 hours
• 17-18 February 2018 - 474mm within 48 hours
(g) - (l) A report for the 2018 overflow events is being prepared and will be published on the Water Corporation website and provided to all interested stakeholders; no similar reports were prepared for the historic 1997 and 2000 overflow events.
(2a-d) From approximately 6.30am on 30 January 2018, to approximately 7.30pm on 31 January 2018; and from approximately 3am on 17 February 2018 to approximately 3am on 18 February 2018.
(2e) Yes
(2f) Not applicable
(2g) January 2018 event: 16.1 million litres; February 2018 event: 23.7 million litres
(2h) Not applicable
(2i) Unknown
(2j) Water sampling was only able to be undertaken when it was safe for employees to do so. As a result, there was limited data with which to accurately calculate the nutrient contribution from the overflows to Roebuck Bay.
(k) The Broome South wastewater treatment plant is designed to cater for inflows of up to 3.5 million litres per day while maintaining sufficient storage to cater for a 1 in 50 year rainfall event.
(3a-c) Design and operation of all Water Corporation wastewater treatment plants is regulated by the Department of Water and Environmental Regulation and the Department of Health. The Water Corporation has a licence under the Environmental Protection Act 1986 which requires any wastewater discharge into the environment from the treatment ponds to be reported and investigated.