In 2019, the Council completed comprehensive City-wide floodplain mapping, identifying areas at risk of flooding. The mapping incorporated a range of future scenarios, including infill development and the continuing effects of climate change.

Following the floodplain mapping, the Council developed and endorsed a Stormwater Drainage Program, which is being implemented in stages over a 15-year period. This program includes the renewal and upgrade of the City’s stormwater infrastructure—such as pipes, culverts, inlets, and junction boxes—to ensure it meets the Council’s service level standards for effective stormwater management.

The Trinity Valley drainage catchment encompasses areas within the suburbs of St Morris, Trinity Gardens, Maylands, and Stepney.

The primary objective of the Trinity Valley Stormwater Drainage Upgrade Project is to enhance flood protection for properties and dwellings against a 1 in 100-year rainfall event. This will be achieved by:

> increasing the capacity of the stormwater infrastructure;
> utilising Council reserves as detention areas; and
> reducing the volume of stormwater conveyed downstream during storm events.

The project is being delivered in four stages. Stages 2 and 3 were completed in May 2024, which involved the installation of large culverts, pipes, and pits within the roadway, followed by full-depth pavement reconstruction at:

> Albermarle Avenue and Ashbrook Avenue, Trinity Gardens (Stage 2); and
> Amherst Avenue and Jones Avenue, Trinity Gardens (Stage 3).

Stages 1 and 4 will be undertaken in 2025.

Similar to Stages 2 and 3, Stage 1 will involve the installation of large culverts within the roadway at Clifton Street, Maylands. For more information, visit the Trinity Valley Stage 1 major projects webpage.

Stage 4 will be undertaken in the suburbs of Firle and St Morris. The work includes the installation of new stormwater infrastructure (i.e. underground pipes and pits) in Gage Street, Seventh Avenue, Green Street, Third Avenue and Glynburn Road.

A detention basin will also be built in St Morris Reserve to temporarily detain water if there is a major storm event. These works will alleviate the risk of flooding to properties in the direct area and downstream.

Stage 4 also includes an upgrade to St Morris Reserve and road resurfacing on Seventh Avenue (between Gage Street and Green Street) and Green Street (between Seventh Avenue and Third Avenue).

The construction of a detention basin will change the landscape of St Morris Reserve. The existing playground, basketball court and furniture at St Morris Reserve are nearing the end of its life. Therefore, this project presents an ideal opportunity for the Council to consider the upgrade of existing assets.

The St Morris Reserve upgrade includes a new playground, a public toilet, a basketball court, BBQ, picnic shelter, furniture, paths, landscaping and irrigation.

To accommodate the new stormwater infrastructure, some alterations to existing SA Water connections needs to be undertaken first. SA Water will undertake these works from 6 January 2025 and will contact any impacted residents ahead of the works occurring.

The stormwater drainage works and St Morris Reserve upgrade are expected to commence late February to early March 2025 and be completed late 2025 (weather permitting). The Council is engaging with local stakeholders to limit the impact of construction activities on local business and residents where possible while ensuring the safety of workers and road users.

The construction work to install stormwater pipes and pits requires large trenches to be excavated in the roadway. Some roads will require a reduction to one-way traffic and small sections of road may be completely closed while works are undertaken. Where necessary, short-term detours will be in place during road closures.

Some night works will be required to construct new drainage on Glynburn Road and minimise impacts to peak hour traffic flows. Further information will be provided to local residents prior to any night works occurring.

For public safety, St Morris Reserve will not be available to the public while the works are undertaken. Temporary fencing will be erected around the reserve work site to restrict access during the detention basin construction and reserve upgrade.

The Council has over 180 hectares of open space including 72 parks and reserves and 26 playgrounds to enjoy. The closest ones to St Morris Reserve are Koster Park, Syd Jones Reserve and Adey Reserve. Find out more about the Council's park locations and facilities at: www.npsp.sa.gov.au/plf

Additionally, there are 10 dog off-leash areas in the City for you and your dog to enjoy. Find out more about the Council’s dog off-leash areas at: www.npsp.sa.gov.au/dol

Pedestrian access to properties will always be maintained. However, at some time during construction, access to your driveway may be temporarily restricted. If your driveway access is affected, we will contact you ahead of these works occurring.

Property owners will not be required to modify their existing stormwater systems or connections to the street.

To construct the new detention basin and upgrade the reserve, all existing trees in St Morris Reserve will be removed. In addition to new lawn and gardens, over 140 new trees will be planted as part of the reserve upgrade.

You can learn more about the project by visiting our website at: www.npsp.sa.gov.au/projects/trinity-valley-drainage-upgrade-st-morris-reserve-stage-4 or by contacting our Citizen Services team on 8366 4555.

If you would like to be kept up to date as works progress or have a question for the project team, please email: trinityvalley@npsp.sa.gov.au.

To receive updates on our major projects, please subscribe at: www.npsp.sa.gov.au/project/subscribe