Managing impacts in Kensington
In delivering the Metro Tunnel Project, we want to minimise the inconvenience and impacts of construction on local communities and the environment.
Environmental Performance Requirements (EPRs) have been developed in consultation with key stakeholders throughout Metro Tunnel's planning process to avoid, reduce or manage construction impacts.
Managing air quality
Part of our construction planning process is the completion of Air Quality Impact Assessments. These assessments are undertaken prior to construction activities starting.
Managing air quality
Minimising the creation of dust is one of the key measures we use to help manage air quality. To do this we:
- Use water trucks to spray down exposed work areas and surfaces
- Seal and/or remediate areas as soon as possible after works are completed
- Design haulage routes that see vehicles travel on sealed surfaces and use water trucks on unsealed roads within construction sites
- Cover truck loads when travelling on public roads
- Use wind break structures
- Minimise double handling of materials
- Seed, stabilise, cover or contain stockpiles where necessary
- Install construction enclosures with concrete floors and truck wheel washers on sites that can accommodate them
- Monitor weather conditions and adjust work programs as required to respond to dry or windy conditions
- Install rumble grids at work site entry points to prevent the transfer of dirt and mud onto public roads
- Use street sweepers to keep the roads clean
- Apply spray on polymers to stabilise work surfaces and decrease the amount of dust generated
Monitoring air quality
Air quality monitors collect data that ensures we are alerted when levels are approaching guideline targets during construction and so that we can regularly review these results to improve how we manage dust impacts.
Also key to how we monitor air quality are inspections and audits of our dust management and air quality measures in line with our air quality EPRs.
Air quality monitors are installed in several locations across our work site on Childers Street. They will remain there for the length of construction to measure coverage across different areas of our site.
Noise and vibration
Predicting noise and vibration
The use of heavy machinery such as piling rigs, cranes, excavators and tunnel boring machines (TBMs) during construction will generate varying levels of noise and vibration.
Prior to the start of works, a Construction Noise and Vibration Impact Assessment (CNVIA) is prepared by qualified acoustic consultants who undertake extensive modelling of the predicted air-borne and ground-borne noise and vibration impacts.
The purpose of the CNVIA is to:
- Outline construction activities and the potential noise and vibration impacts
- Identify which construction activities and equipment will require noise and vibration mitigation measures to meet the project’s EPRs
We assess and model construction noise and vibration impacts by:
- Determining baseline noise measurements near the construction site
- Modelling typical construction scenarios based on the equipment to be used, and the proposed times and locations where they will occur
- Running models to determine predicted impacts for both noise and vibration.
When noise and vibration modelling predict guidelines will be exceeded, and the construction methodology can’t change, the project team will work with key stakeholders and the community to determine the best way for impacts to be managed.
Managing noise and vibration
We are using a number of measures to manage noise and vibration. These measures are consistent with the recommended EPRs and meet the Environment Protection Authority (EPA) Victoria’s noise level guidelines and relevant noise and vibration standards. With a focus on reducing the noise at its source, these include:
- Enclosing equipment with acoustic curtains
- Considering the use of low impact construction techniques as part of the construction planning process
- Setting up designated traffic routes for construction vehicles, directing construction traffic away from residential areas and the local road network
- Using designated loading and unloading areas to minimise machinery movement
- Turning equipment off when not in use
- Placing acoustic hoarding around the construction site
- Fitting construction vehicles and equipment with broadband reversing beepers
- Training staff in noise reducing behaviours.
Other controls include:
- Shielding stationary noise sources
- Limiting high noise and vibration-causing activities to standard construction hours where possible
- Reviewing construction methodologies and using innovation to minimise impacts as much as possible.
Monitoring noise and vibration
Throughout the construction of the Metro Tunnel, attended (in person) and unattended real-time noise and vibration monitoring is undertaken. This monitoring ensures the accurate recording of all noise and vibration levels and ensures compliance with EPRs.
Monitors measure and report on noise and vibration levels to ensure we are alerted when levels are approaching guideline targets during construction so that, if required, additional measures can be applied to help reduce impact.
A noise monitor and vibration monitor is currently installed at a property near our work site on Childers Street and will remain there for the duration of construction. As our construction site expands to occupy the full length of Childers Street, we will install monitoring devices in additional locations to ensure monitoring is undertaken at different areas of our site.
Having permanent monitors close to the source of works, and doing in person monitoring, gives the project team access to real time noise and vibration data. This data allows us to compare real noise levels against modelled noise levels and helps us to improve how we mitigate against noise.
Construction requires the disturbance and excavation of soil. Working with, removing and managing contaminated soil is undertaken on a daily basis across most work sites in Melbourne and specifically at our work sites in Kensington.
It is common for soil found in the rail corridor to be contaminated given the age and industrial nature of the railways in Melbourne. In addition, areas in Kensington were previously a landfill site, which adds to the types of soil found.
There are strict rules for how we manage excavated contaminated material, including processes for identifying contaminants as well as a specific set of methods and procedures for safely removing them from site. The Metro Tunnel Project has comprehensive management systems in place for:
- Soil testing
When we disturb soil or remove soil from work sites, we first sample and test the soil to understand the type and quality.
Sampling and testing is done as per Environment Protection Authority's (EPA) Victoria Industrial Waste Resource Guidelines (IWRGs). This is a requirement of the project's Spoil Management Plan, which is prepared in consultation with the EPA and audited by an Independent Environmental Auditor.
Soil testing is undertaken by qualified specialists and verified.
Once soil has been tested it is classified. Classifications include prescribed industrial waste (Categories A, B, C) and fill material (soil with low to zero contamination and safe for re-use). Categories are determined by the type and quantity of contaminants found. Category A being the highest level and Category C being the closest to fill material.
The results of soil testing conducted across Metro Tunnel works areas in Kensington show that most soil is designated as fill material. Not surprisingly given the area's history, some Category A or asbestos containing material has been found as part of sampling investigations, as well as some pockets of Category B and Category C materials. If disturbed, the Category A, B and C soils will be carefully managed and safely removed.
All classified soil will be separated out and disposed of in accordance with the EPA Guidelines and the project's approved soil management procedures.
The Metro Tunnel Project has a comprehensive Health and Safety Management Plan to ensure that members of the community and our project team are not exposed to hazardous materials. Measures in place to ensure the safety of the community and project team prior to soil being removed include:
- Avoiding unnecessary handling of potentially contaminated soil
- Selection of equipment to manage dust
- Water carts to dampen the soil and manage dust
- Handlers to use personal protective equipment
- Stockpile management.
Air quality monitoring is also implemented to monitor local air quality during works.
The air quality monitors will provide real-time measurements of air quality, including dust generated during construction activity and soil removal.
During the removal of soil, safety measures will include exclusion zones and water carts to dampen the soil and prevent dust.
Soil is loaded onto trucks using machinery such as diggers and excavators.
All trucks used to transport contaminated soil are licenced by the EPA. All trucks removing soil and material from Metro Tunnel work sites are covered to prevent dirt and dust escaping.
Category A, B and C soil will be separated out and disposed of in accordance with the EPA Guidelines and the Project's approved spoil management procedures. This material will be transported to a pre-determined location and facility that is licenced to accept each of the corresponding types of waste. Fill material can be re-used on site or transferred to other project sites where it can also be re-used.
All soil handled and removed from site is managed by an EPA waste transfer certificate system.
Each completed waste transport certificate is provided to the EPA.
Download the Soil management in Kensington fact sheet (PDF, 2.5 MB).
Environmental Performance Requirements
A number of other mitigation measures have been developed to avoid, reduce or manage construction impacts for the western tunnel entrance in Kensington.
Some of the recommended mitigation measures for the western tunnel entrance include:
- Planning and carefully managing access routes to minimise impacts on residents and users of the area.
- Undertaking property condition surveys before construction begins to record the existing condition of buildings and residences in close proximity to tunnels and construction sites.
- Offering temporary relocation or alternative accommodation for residents who may experience adverse noise levels. This will be considered on a case-by-case basis.
- Providing alternative routes for pedestrians, cyclists and vehicles to maintain connectivity and safety for road and shared path users of Childers Street, JJ Holland Park and South Kensington station.
- Offsetting the loss of public car parking along Childers Street.
- Identifying alternative routes for trucks to access the Lloyd Street Business Estate in Kensington.
- Developing railway closure plans that minimise the disruption to rail services during construction.
- Implementing measures for providing advance notice of significant milestones, changed traffic conditions and periods of potential high noise and vibration activities.
- Monitoring dust and air quality, in line with Environment Protection Authority Victoria requirements, and addressing air quality requirements for nearby residents and businesses.
- Ensuring above-ground structures are responsive to heritage places in terms of height, massing, form, façade articulation and materials.
- Preserving the broader landscape and recreational values in the reinstatement of shared pathways and other public spaces.