New Sewage System – What I’ve learnt today 8 July 2020

On the 29th June 2020 David Spiers MP, Minister for Environment and Water wrote to me (and I’m sure you too) that he directed SA Water to transfer all properties that are currently connected to the Community Wastewater Management System onto SA Water’s mains sewage system.

In this letter he states “Importantly, you will not be required to pay for the cost associated with fixing this long-standing issue, and critical work will get underway within 12 months.”

On Tuesday 7th July 2020 Tea Tree Gully Council held a Special Meeting of Council. The agenda for this is available on the Councils website (Agenda of Special Meeting of Council – 7 July 2020). The part of specific interest regarding Sewage and the CWMS is Item 7.2 page 53 and 54, the section headed Upgrade and Renewal of CWMS Infrastructure. This part is reporting on specifically the Jasper Catchment which includes properties along Elizabeth St, Steventon Drive, Coulls Road, Tay Court and Visma Crt in Banksia Park.

I include a copy/paste of that part of the document here (as the whole document is quite big.

Upgrade and Renewal of CWMS Infrastructure

There were a number of defective assets that could not be effectively rehabilitated due to site and engineering constraints. These assets are located within the Jasper Catchment and are along Elizabeth Street, Steventon Drive, Coulls Road and Tay Court in Banksia Park. New sewer alignments will be required to replace the existing defective CWMS assets. Refer to Figure 7 shows the proposed new alignment that would be constructed to sewer standard.

The following are the key considerations relating to the upgrade of the CWMS infrastructure along Elizabeth Street, Steventon Drive, Coulls Road and Tay Court, Banksia Park.

  1. The CWMS assets are defective and there is a significant risk that the asset may fail if timely intervention does not occur.
  2. The CWMS assets on Steventon Drive and Elizabeth Street are trunk mains and provide CWMS services to approximately 450 customers located upstream. A critical failure of the infrastructure would lead to costly emergency work and significant service disruptions for the affected customers. In addition to the 450 customer upstream, there are another 94 customers with connection points to these assets.
  3. The presence of a watercourse that runs between Coulls Road and Steventon Road make it an environmentally sensitive receptor and subject to the EPA Water Quality Policy 2015.
  4. This is a significant design and highly complex due to existing underground services, presence of ground water, system hydraulic issues, existing established dwellings and site constraints. It is estimated that the detailed design and SA Water approval for this work would take 15 months.
  5. The detailed design will be the upgrade of the CWMS main to sewer standards. It is not necessary for approximately 50% of the properties to convert their internal sanitary drainage to sewer standards because the location of their connection points would remain in the same location. However, modification of sanitary drainage will be required to connect the remaining 50% of properties to the new proposed sewer main.
  6. The capital cost estimate to upgrade the sewer main only is estimated to be $2.9 million. This includes the cost estimate for the detailed design component, which is between $60,000 to $90,000. All capitalised expenditure will be considered in the CWMS divestment prudential report that will be presented to Council for consideration.
  7. 3 of the 4 roads (excluding Elizabeth Street) are due for road upgrades in the near future with these works currently on hold pending the upgrade of the CWMS system in this area.

It is suggested that Council should exercise due diligence and undertake the design and planning necessary to undertake the necessary upgrade work.

Figure 7. Proposed new alignment to upgrade CWMS infrastructure along Coulls Road, Steventon Road, Elizabeth Street and Tay Court, Banksia Park

My thoughts and fears with this.

My house is on Coulls Road with the current CWMS running to the back of the block by the creek (the Steventon Drive side of Coulls Rd). It can’t continue to run to the back by the creek as it’s “subject to the EPA Water Quality Policy 2015” (item 3 in the report).

For those that live near me know the reason is the land slopes down to the back.

What this report is proposing is to re do the pipes so it goes to the front of the property to a new pipe in Coulls Road. This will be an enormous task on almost all the properties in Coulls Rd. For a start, sewerage wont flow up hill so the pipes are going to need to be very deep, lower than what your lowest point is today. Then where to they run the pipes? For me the shortest path is through the carport and up the driveway so lifting all the paving at the back of the house, digging up the concrete through the carport and up the driveway.

I’m sure the government will pay for the digging up and the plumbing, but what about rebuilding afterwards. If it is just a garden bed with some plants, I can live with re-doing that myself, but what about the cost of laying pavers, concreting etc?

UPDATE 9 Jul: Thanks to Cameron on the Facebook chat, the hint on horizontal boring. It looks like this may be a real option for the laying of the pipes although the vertical alignment (needs to slope down on it’s way to the street) is more difficult it looks like it’s possible. For those interested in more on this, see https://en.wikipedia.org/wiki/Directional_boring

Granted this is a Council report, not SA Water yet, but I can’t see any reason it’s going to be done differently considering the research gone into this report already.

Letter from David Speirs MP

This is the letter (with my address clouded for some privacy). I’m sure you would have received this too.