Rodney Stevens
Filtration of the Clarence Valley’s drinking water supply is again back on the agenda following this months Level Four severe water restrictions which lasted 11 days.
The Rushforth Road Water Treatment Plant RRWTP masterplan, which aims to replace the existing reservoir without impacting future construction of a filtration plant, is on the agenda at the February 28 Clarence Valley Council CVC meeting.
Prepared for council by consultant Beca H2O, the masterplan includes the replacement of the existing 32 megalitre reservoir, which is included in CVC’s 2022/2023 Operational Plan, and for future construction of filtration.
“It is recommended that Council progress the Masterplan by commencing the planning approval process for a future filtration plant at Rushforth Road Water Treatment Plant,” council papers state.
Council staff recommend councillors note the masterplan and commence the planning approval process for future construction of a filtration plant by calling open tenders to undertake an Environmental Impact Statement.
CVC first adopted a Drinking Water Management System DWMS at its August 19, 2014 meeting and an updated DWMS was adopted at the May 2020 meeting.
Up until the 1990s, drinking water was extracted regardless of turbidity, then in the early 1990s selective extraction was introduced to improve water quality when turbidity was below 10 Nephelometric Turbidity Units (NTU).
Councils 2014 DWMS saw the turbidity level drop to 5 NTU, then the May 2020 DWMS further dropped the turbidity level to 3.5 NTU.
Currently, CVC water supplies are disinfected at Rushforth Road “by chloramination (adding ammonia to chlorine) as this provides the most stable disinfectant in lengthy pipeline systems because chloramines decay at a lower rate than free chlorine,” council papers state.
Tenders have been called for stage one of the masterplan which will see a 1.5 ML Chlorine Contact Tank and a 16ML Treated Water Storage Tank installed at the RRWTP, estimated to cost $14.7 million in October 2021.
“The provision of a Chlorine Contact Tank will allow the primary disinfection at Rushforth Road by free chlorination while, by adding ammonia after the contact tank, continue to provide for a chloramine residual in the lengthy pipeline network,” council papers state.
Stage two of the masterplan is the conceptual design for filtration to be constructed at the RRWTP and is estimated to cost $63.8 million, with an annual operating cost of $2.1 million.
“The Masterplan has confirmed that gravity flow through the plant is feasible, and all elements of the plant have been conceptually located so that the current plant (with the addition of the chlorine contact tank) can continue to operate during construction,” council papers state.
“Due to its construction cost the filtration plant is classified as State Significant Development, and therefore needs planning approval via an Environmental Impact Statement (EIS).
“It is recommended that Council commence the approval process for a future filtration plant by calling tenders to undertake an EIS.”
The last time council considered filtration at its April 15, 2014 meeting it was estimated the construction and operation of a filtration plant would add $275 annually to the typical residential bill.
“The drinking water risk is not assessed by the State Government as being high enough for funding assistance under the current Safe and Secure Water Program,” council papers state.
“The Rushforth Road water treatment has been allocated a risk score of “4”, while the program funding is currently only sufficient to provide assistance for projects with a risk score of “5”.”
Due to this situation, it is likely that CVC will require loans to fund the water filtration project.