A project to develop a future investment plan for Middlemarch’s wastewater treatment plant (WWTP) and wastewater network is underway.
The DCC is responsible for the collection, treatment and disposal of Middlemarch’s wastewater and has commissioned engineering consultancy Beca to carry out an assessment of the WWTP and wastewater network. This study, which began in July 2020, will develop an investment plan for the whole Middlemarch wastewater system, with options for improvements.
Improving the wider city’s wastewater services has been a key focus for the DCC for some years. This includes services provided in rural areas and Middlemarch is one of the communities to be looked at.
The DCC will be working closely with mana whenua and the Middlemarch community throughout this project, as well as other stakeholders including the Otago Regional Council and the Department of Conservation.
-
What are the issues?
Middlemarch wastewater is collected at the Olive Avenue pump station before being pumped to oxidation ponds, located about 800m south of the township for treatment. The treated wastewater passes through a wetland before what remains is discharged to a dry channel of the Taieri River. In dry weather, no discharge reaches the Taieri River, but when the river is in flood the discharge goes directly into the river.
Parts of the Middlemarch wastewater system are not performing as well as they should, and at times are not meeting current resource consent requirements.
Resource consent for the wastewater treatment plant is due to expire on 1 August 2021. At the end of this year, the DCC plans to lodge an application with the Otago Regional Council for a short term (five year) consent. This will give the DCC time to develop and approve an investment plan before applying for a longer term consent.
Middlemarch has had flooding issues, most recently in November 2018 when very heavy rain meant stormwater overloaded the wastewater pipes, causing wastewater to overflow on to the road. This happens rarely, but any system upgrade would aim to reduce the likelihood of this happening.
Middlemarch’s drinking water comes from bores. This means wastewater and stormwater flooding, and where wastewater is discharged, can affect drinking water quality. The study will also look to reduce the risk of the wastewater system negatively impacting on drinking water.
-
The Middlemarch WWTP study
This long-term study will have four stages and will result in a preferred upgrade option for the wastewater network, the pumping station, the treatment plant and the disposal location.
Stage one began in July 2020 and will run for about six months. This stage includes environmental monitoring of the treatment plant, the Taieri River, surrounding watercourses and groundwater. Stage one will help the DCC understand how the current system is working and provide information to accompany the short-term resource consent application at the end of 2020.
Stages two to four of the study will happen during 2021 and 2022. These stages will identify a wastewater strategy for Middlemarch, including investment options for the whole wastewater system, from the pipes to the discharge location, eventually leading to a preferred option.
-
FAQs
What is wastewater?
Wastewater is everything that goes down a drain inside your home or business. Whether it’s your kitchen, bathroom or laundry, if it goes down the toilet or down a plughole then it is wastewater.
How long will it take until we have an upgraded scheme?
It will be several years before an improved system is up and running. We need to do a lot of investigation and scoping work so we have information about what’s happening now, and what the options might be. We will also need to go through a resource consent process before we can make changes to the system.
Does this project mean we won’t have sewage in the streets again as we did in the 2018 flood?
Recent flooding in Middlemarch is one of the key reasons for this project. One of the aims of the project is to identify ways to reduce the likelihood of significant wastewater flooding.