Planning upgrades to our water and sewer network
We’re responsible for a network of water and sewerage pipes in our service area, more than 20,500 kms. Some of these pipes are more than 100 years old. We assess and replace our existing network of pipes and other infrastructure to reduce the likelihood of failures that cause service interruptions and environmental impacts. As part of our planning, we carry out a range of investigations.
Current water and sewer network planning investigations
Our water and sewer network improvement projects - designed and constructed by our project partners - include pipelines, emergency relief structures and pump stations.
M4 water main, Brunswick and Coburg
Information about investigations and assessments
Topographical or feature contour surveys
Using specialist GPS equipment, a surveyor records details all land features in terms of height, depth, size, and location. These surveys provide insights into a specific piece of land or area – and any features within its boundaries such as an easement, maintenance hole or street furniture. Buildings and other structures, watercourses and drainage lines, trees and hedges are also surveyed and added to these surveys.
Geotechnical and geophysical surveys 
Understanding the ground conditions of an area is critical when designing and constructing new water and sewer pipelines.
Geotechnical surveys include investigations using a drill
rig attached to a vehicle. Vertical bore holes are drilled, and
the core samples is removed and analysed. Once the
sample has been removed, we restore the area to how it
was before the sample was removed
Generally, bore holes are at regular intervals, are approximately 6 meters deep and take a day to complete, depending on location, traffic conditions and weather.
We also complete geophysical or seismic surveys to determine the depth of rock. These surveys use a slow-moving, mobile mapping vehicle, equipped with LIDAR sensors, to record sound signals. A small weight is dropped onto the ground and the sound waves are recorded.
As both types of surveys require the use of vehicles and specialist equipment, there will be detours and traffic management around the site.
Service proving
To find and map underground assets and services such
as water, sewer and gas pipes, stormwater drains, telecommunications and electrical services, a range of investigative techniques are used, including
Non-Destructive Digging (NDD).
NDD uses a vacuum truck with a high-pressure water jet to create small holes that enable us to safely identify buried services. As many of these existing services are likely to be in the road or under footpaths, we put traffic management
around where were working.
Ecological surveys
To assess the potential impact that a new pipeline will have on the natural environment (habitats, species and existing ecosystems), we complete ecological surveys.
These surveys document detailed findings and potential impacts and suggest measures to reduce these impacts. Ecological survey information is used to prepare a Vegetation Retention and Removal Plan.
Cultural Heritage Management Plan
Under the Aboriginal Heritage Act 2006, a Cultural Heritage Management Plan (CHMP) is required when a project is being planned in an area of 'cultural heritage sensitivity', including registered Aboriginal cultural heritage places, landforms, and areas likely to contain Aboriginal cultural heritage.
A CHMP is includes an assessment of the project area to determine the nature and extent of any Aboriginal cultural heritage that may be present. This information may be obtained through background research, interviews with Traditional Custodians/Owners, a ground surface survey, sub-surface testing and/or archaeological excavation.
The CHMP is a written report prepared by a qualified heritage advisor, and it includes actions to protect areas of sensitivity an Aboriginal cultural heritage.
Depending on the project, a ‘standard assessment’ or ‘complex assessment’ is required.
- A standard assessment involves archaeologists walking the project area, taking photos, and documenting landforms and any existing cultural and/or historical heritage. It may include sub-surface investigations (such as ground penetrating radar surveys, resistivity surveys, remote sensing, ground magnetic surveys, electromagnetic surveys, and soil and sediment testing with a manual auger no larger than 12cm in diameter). The results are used to identify locations where additional excavations are required, in consultation with the Registered Aboriginal Party.
- A complex assessment is required when Aboriginal cultural heritage is, or is likely to be, present in a project area, and when it’s not possible to identify the nature, extent, and significance of the Aboriginal cultural heritage without disturbing (or excavating) the area. Also referred to as sub-surface testing, different excavation methods are used, including the use of a manual auger, test pits that are dug using a shovel or small hand tools, and mechanical excavations. Complex assessments are supervised by a person appropriately qualified in archaeology and completed in accordance with archaeological practice.
CHMPs must be approved by the appropriate Registered Aboriginal Party (RAP) before planning permits, licences and work authorities can be applied for.
Visit the Victorian Government's Cultural Heritage Management Plans page for more information.
Victorian Heritage
The Victorian Heritage Register lists all known historical archaeological sites in Victoria that are protected under the Heritage Act 2017. It includes the state's most significant heritage places, objects, and historic shipwrecks. If a proposed project impacts a heritage listed site, a Victorian heritage permit and plan is required.
Visit the Victorian Government's page on heritage listings for more information.
We complete most of these surveys when we're planning our water and sewer network improvement projects. Sometimes we also complete flood surveys, acoustic and vibration assessments and contaminated ground investigations.