sportsground-banner.jpg

Foxglove Oval

Enquiries

For further information on this project please contact us at foxglove@hornsby.nsw.gov.au or by calling us on 1800 413 700.

Foxglove Oval, Mt Colah

Foxglove Oval is a popular local sporting and recreation field in Hornsby Shire. It is a former landfill site. The existing sports fields were established after the landfill closed in 1980.

Council has been monitoring below-ground wells around Foxglove Oval to check for landfill gas. Landfill gas is a gas mixture created as the landfilled waste decomposes. Results from the monitoring found levels of methane and carbon dioxide above the NSW Environment Protection Authority (EPA) guidance values in several locations close to the inside perimeter of the oval.

Council notified the NSW EPA of these results and engaged environmental specialists GHD to undertake further monitoring, undertake air testing inside some surrounding homes and to identify potential remedial actions if required.

In February 2020, we updated our local community, advising that the NSW EPA had declared Foxglove Oval, Mount Colah "a significantly contaminated site" due to its former use as a landfill site. This does not mean Foxglove Oval is unsafe to use, with the site still open for sporting and recreational activities. It does however mean that Council needs to undertake certain activities including the installation of environmental monitoring wells on and around the site to monitor potential contamination related risks at the site.

In December 2020 and February 2021, new groundwater monitoring wells were installed around Foxglove Oval to assist in further investigating landfill gas and groundwater conditions at the site. Council has since continued to carry out monitoring of the wells at the oval, with recent tests identifying levels of landfill gas in the north east corner of the oval in exceedance of the NSW EPA guidelines. Council is working with residents in close proximity to the affected wells and will be undertaking in-house monitoring at these properties. Council believes the risk of landfill gas entering residential properties is low and air testing will confirm this.

Council worked closely with GHD (environmental consultants) throughout 2021 and the first half of 2022 to design a passive remediation system intended to reduce off-site migration of ground gas.

In June 2022 Council appointed EnviroPacific Services (EPS) to complete construction of this ventilation system. This construction was completed in June 2023.

Landscaping of the site commenced after construction and will be maintained by Council.

Community Updates

Below is the latest project updates to provide you with further information about the broader program of works we will be completing in the area.

View the previous updates below:

During in-home monitoring during the week of 23 March 2021, elevated levels of landfill gas were detected at two homes adjacent to the Oval. As per protocols, Hornsby Shire Council notified Fire and Rescue NSW (FRNSW) who attended the homes, and also notified the NSW Environment Protection Authority (EPA). FRNSW exercised caution and requested that the families vacate their homes until it is safe for them to return. Council has found these families alternative accommodation and is maintaining close contact to ensure all their needs are met. More information is in the letter below.

Frequently Asked Questions

BACKGROUND of Environmental Investigations

Hornsby Shire Council (Council) became aware of the possibility of gas moving from the site in September 2016 when an independent report was commissioned by a neighbouring property owner. As a result, Council has been monitoring ground wells around Foxglove Oval to check for landfill gas since April 2018.

Monitoring of methane and carbon dioxide levels in below-ground monitoring wells has found the levels to be above the NSW Environment Protection Authority (EPA) guidance values in several locations close to the perimeter of the oval. Environmental specialists GHD has been engaged to assist in additional testing and developing remedial options and recommendations.

The Voluntary Management Proposal (VMP) is a high-level plan that guides the environmental investigation of the former landfill and the associated contamination. Remediation and validation are undertaken if the contamination presents a potential risk to human health or the environment in accordance with EPA guidelines. The VMP was prepared in May 2020, and then revised and approved in February 2022. The VMP has been reviewed by the independent Site Auditor and agreed between NSW EPA and Council.

Since the original VMP was prepared, the data collected has improved Council’s knowledge of the site and the VMP has been updated to reflect this information. The approved VMP will allow for planning of future management and remediation tasks. The VMP is a public document and can be viewed on the EPA website. (https://app.epa.nsw.gov.au/resources/clm/docs/html/n20221702.htm)

An Interim Environment Management Plan (IEMP) developed by GHD and agreed to by the EPA also guides the monitoring, investigation and site management works.

Yes. Investigations on the western, northern, southern and eastern boundaries have confirmed the need for remedial works. Due to the proximity of residents to the Northern Batter, work in this area is being prioritised. The passive remedial options proposed include installing several gas vents to collect and release gas from the ground to the atmosphere.

Council informed the NSW EPA when landfill gas was detected above EPA guidance criteria in some below-ground monitoring wells installed within buried waste materials. The EPA then declared Foxglove Oval to be ‘significantly contaminated land’ under the Contaminated Land Management Act 1997.

The VMP is an agreement between Council and the EPA to address the contamination issue. Council continues to work closely with the EPA.

To accelerate the remedial action needed at the Oval, the EPA will issue a Clean-up Notice which acts as the legally binding document that requires Council to take immediate action on the northern boundary to limit unacceptable levels of landfill gases and leachate moving offsite.

This web page will be kept up to date with any project news and developments. If you have any other enquiries, you can contact us via the methods below:

Phone: 1800 413 700
Email
: foxglove@hornsby.nsw.gov.au

Should you wish to view the VMP and IEMP, or other project documents available you can download from the links below:

HEALTH and SAFETY issues

The life cycle of a landfill shows that landfill gas is released as waste breaks down over the decades. When a landfill is closed, there is an initial spike in emissions which rapidly declines over time. As Foxglove Oval is 40 years old, the amount of landfill gas being released is past the peak rate. Based on modelling, the peak rate of gas generation would have been about 1,139 m3/hour in 1982. The current maximum gas generation rate is modelled to be 53 m3/hour. This represents about a 95% reduction in the maximum rate of gas generation from 1982 to 2021.

The results of continuous monitoring in the area since 2019 indicate that the landfill gases pose a low risk to the general community. We are continuing to undertake investigations to confirm that this is the case. The safety, health, and wellbeing of all residents and oval users remains Council’s top priority.

Landfill gases can be concerning if concentrations are greater than EPA guidance values. The guidance values as determined by the EPA are described in the Solid Waste Landfill Guidelines (2016).

The two most common landfill gases are methane and carbon dioxide. These gases are not toxic and do not build up in your body. The risk posed by methane is combustion, and carbon dioxide can cause asphyxiation in an enclosed or confined space.

No. Methane and carbon dioxide do not build up in the human body. They mainly present a risk if they accumulate in an enclosed space where there is inadequate ventilation.

There is information available online about methane and carbon dioxide – the two main gases created in a landfill as the waste breaks down. Additional information on landfill sites and gases can be found on the NSW EPA website.

No. The Oval remains open for sporting and recreational activities, unless the remedial activities require some short-term closure, in which case Council would notify affected sporting groups to advise of any changes to the Oval use.

The main risk would be if gases were to build up in an enclosed space. Because the Oval is an open space, the risk of landfill gas impacting people using the Oval is very low. Regular sporting activities can continue as normal unless Council notifies otherwise. Part of the ongoing works include monitoring gas at the Oval surface, amenity building and perimeter wells at the Oval.

The regular monitoring being completed as per the VMP and IEMP indicates that the risk of landfill gas impacting upon residential backyards is generally low and acceptable.

Results from in home air testing and reporting indicate that the risk to local residents is low. Council is working with GHD on the landfill gas management strategy for the Northern Batter and these works are designed to reduce landfill gas levels moving from site to a low and acceptable level in accordance with the EPA regulations.

No. The Oval remains open for sporting and recreational activities, unless the remedial activities require some short-term closure, in which case notification to affected sporting groups would be provided in advance.

The main risk would be if gases were to build up in an enclosed space. Because the Oval is an open space, the risk of landfill gas impacting upon people using the Oval is very low. Regular sporting activities can continue at the Oval as normal unless Council notifies otherwise. Part of the ongoing works include monitoring gas at the Oval surface, amenity building and perimeter wells at the Oval.

If ground gas concentrations are detected above EPA guidance values, then established protocols are followed. The exact requirements depend on where the ground gas is detected and the extent of the detections. The protocols may include additional monitoring to confirm readings and/or monitoring in new locations. Management controls may also be required depending on these outcomes and the assessed level of risk.

For example, elevated levels of landfill gas were detected at two properties adjacent to the Oval in March 2021. As per protocols, Council notified Fire and Rescue NSW (FRNSW) who attended the homes, and also notified the NSW EPA. Additional monitoring continues at these properties to fully understand the potential risks.

The well-being of our community is our top priority.  As guided by our environmental consultants and an EPA accredited independent site auditor, Council believes the risk of landfill gas entering properties is low, and the air testing in properties program has confirmed this. In the event landfill gas nearby or in your home is found to exceed NSW EPA guidance values, we will discuss what is needed to address the immediate issue. An initial action may include increasing ventilation in the affected area(s). Ongoing management and mitigation measures will be discussed on a case-by-case basis.

The well-being of our community is our top priority. It is common for old landfills to be closed and re-established with residential properties developing around them. Council’s environmental consultants have completed several rounds of air-monitoring for methane gases at the Oval, and in some of the homes adjacent to the Oval, over the past two years. The results tell us that while some remedial work is needed to stop landfill gases moving off site, the levels off site are not posing an unacceptable risk to the residents.

Based on the in-home testing results, Council can confirm the chances of landfill gas entering homes is very low. The levels of landfill gas monitored in homes to date have been below guidance values. Monitoring at the Oval will continue throughout the remedial work and will only occur in homes if and when required.

The guidance values are determined by the NSW EPA. They are described in the Solid Waste Landfill Guidelines (2016).

Yes, there will be ongoing testing of and around the Oval to monitor levels of landfill gases, for as long as the EPA deems it necessary.

There is information available online about methane and carbon dioxide – the two main gases created in a landfill as the waste breaks down. Additional information on landfill sites and gases can be found on the NSW EPA website at www.epa.nsw.gov.au.

ONGOING MONITORING and REMEDIATION WORKS

The Northern Batter is along the Oval’s north-eastern boundary and is the area closest to residents. By mid-year, construction is expected to commence and will include installing several bores into the landfill with vents to allow landfill gasses to collect and release from the ground to the atmosphere. The aim of these vents is to create a row of vents that act as a virtual curtain or wall to limit gas moving offsite.

Landfill gas is released to the atmosphere under natural pressure. The gas being vented is mostly methane. The landfill gas that smells is typically sulphuric acid or rotten egg gas. Council anticipates that there will only be traces of this gas, and very little, if any odour. As the vents are likely to be 4m high at the Oval boundary, the gas will diffuse into the atmosphere. Council will monitor the vents for odour and if an unacceptable level of odour consistently occurs, this will be addressed.

Wells and vents serve different purposes. Wells are usually located on the edge of former landfill and are designed to detect whether there is gas in the ground and if it is moving offsite. Gas samples are taken from these wells and measured. Vents are installed to provide a passive pathway to allow gas to be released from the ground. They are a less-invasive measure than installing a deep trench or bounding wall.

Council is obliged to execute actions in accordance with the performance schedule of the VMP (Part 3) and as detailed in the Interim Environment Management Plan (IEMP).

Council has already undertaken repair and enhancement of the perimeter landfill gas and groundwater monitoring well network, installed leachate monitoring wells, and commenced investigations to determine the requirement for repair and/or enhancement of the existing leachate and stormwater management systems, in accordance with Sections 2a and 2b of Part 3 of the VMP. Monitoring works outlined in the IEMP are currently being implemented in accordance with Section 2c of Part 3 of the current VMP.

The regular ongoing environmental monitoring program will continue and will inform remediation required at different locations around the Oval. At the Northern Batter, any further remediation will depend on the outcomes of the monitoring after installation of the bores and vents, described above. While monitoring is anticipated to continue, improvements in results may decrease the frequency (e.g. monthly to quarterly).

The monitoring at other locations around the Oval (eastern, western and southern areas) will be continued and if remediation is required, we will discuss these remediation measures with residents at an appropriate time (i.e. when options are developed).

Throughout this project residents have been kept informed by:

  • Written updates to the local community via regular newsletter
  • Written updates to Oval users through relevant associations
  • Face to face liaison with the local community through community drop-in sessions at the Oval as required
  • Direct liaison with local residents via phone, online forums, and/or face to face visits
  • Project information published on Council’s Foxglove Oval project web page including FAQs.

If you require any specific information about the project please contact the project team on the details below.

Phone: 1800 413 700

Email: foxglove@hornsby.nsw.gov.au

At this stage, our focus is ensuring the safety of our residents and our local community in the vicinity of Foxglove Oval. There are a number of open space areas across the Hornsby Local Government Area that are located on former landfill sites such as Brickpit Park at Thornleigh and Westleigh Park.

Whilst we don’t have any information indicating that there is a problem at any of the other sites, we are reviewing them to ensure they meet current standards.

In accordance with the Interim Environment Management Plan (IEMP[1]), Council has been undertaking extensive landfill gas monitoring and reporting on site buildings, the Oval surface, sub-surface perimeter wells, sub-surface service pits/penetrations and offsite buildings, as well as regular testing of groundwater, surface water, leachate and seepage monitoring and reporting.

Monitoring and reporting was first conducted in March 2020 and has been occurring monthly since May 2020, with the exception of July 2021 when changing COVID circumstances meant monitoring could not be completed.

Council has acted in accordance with the recommendations of these monthly monitoring reports which have typically been to report exceedances to the EPA, to undertake ongoing monitoring, and to install and maintain appropriate signage and fencing at certain subsurface pits and surface water and leachate locations.

An investigation into the operation and effectiveness of the leachate collection system is currently underway, together with CCTV inspection of sewer and stormwater pipework, to determine the condition of the pipes and assess whether they may be a source of contaminants or a preferred pathway for contaminants to travel off site.

In 2022 supporting investigations into the mapping of local geological conditions, geophysical characteristics of the perimeter areas and local background carbon dioxide levels were also completed at the request of the Auditor to strengthen the understanding of the prevailing landfill conditions in the vicinity of Foxglove Oval.

[1] (the IEMP is guiding the remediation until the latest version of the VMP is endorsed by the EPA)

The need and timing for any further remediation will be determined by the outcome of current investigations and ongoing monitoring of the site.

Council is required to stop landfill gases and leachate moving offsite into neighbouring properties. The contamination source is unlikely to be eliminated as the former landfill is the source.

Construction works along the northern boundary commenced in August 2022 and were completed in June 2023.

Operating hours at the site are 7am – 5pm Monday to Friday.

The landfill gas venting component of the remediation system is designed to collect landfill gas from underground along the batter and release it to the atmosphere under natural pressure through 4metre-high vertical vents (similar to the height of the existing ball fence along the northern boundary). The underground component of the remediation system includes landfill gas collection bores at the bottom of the batter and subsurface pipework to connect the bores to the vents.

In June 2023, the site was returned to Council to complete landscaping of the northern batter, in consultation with the locally impacted residents.

When contaminated waste is excavated it must be placed in containers or controlled stockpiles prior to offsite disposal. Waste in the working area (that is not removed) will be covered at the end of each day. Both disposal and management of contaminated waste will be in accordance with the site specific documents developed for the work, and in line with NSW EPA Landfill Guidelines (2016).

All non-contaminated waste generated during the construction will be stored in appropriate containers or controlled stockpiles prior to offsite disposal.

Disposal will be in accordance with the site specific documents developed for the work, and in line with NSW EPA Landfill Guidelines (2016).

Potential impacts to residents and the local community include reduced privacy from removed vegetation, noise, vibration, and odour from disturbance of landfilled waste and/or gases, and dust. Vibration, odour and noise surveys were completed in advance of construction to confirm background levels. These issues will be monitored throughout construction to ensure any adverse impacts are appropriately managed.

There may also be minor temporary traffic changes around the Oval, due to the movement of construction vehicles and/or machinery, or for other safety reasons determined by the contractor and Council.

Construction works will be in accordance with the site-specific documents developed for the work, and in line with NSW EPA Landfill Guidelines (2016).

Clearing the vegetation is likely to be the noisiest component of the works. Sound barrier fencing along the lower boundary will be installed to help soften construction noise close to adjacent residents.

While the permanent fencing is yet to be finalised, Council expects it to be similar to the existing 3.6 metre ball fence installed along the northern boundary.

If the landfill cap is disturbed during the work, the contractor is required to reinstate any capping as part of the construction works, using existing materials or approved alternatives (such as man-made synthetic capping materials). This work needs to be undertaken in accordance with the site specific documents developed for the work, and in line with NSW EPA Landfill Guidelines (2016).

GENERAL QUESTIONS

The former landfill has existed here since the 1970s and the suburb has grown up around the site. Council has seen no evidence to suggest property values have been negatively affected over the years and remediation plans are underway to address any future risks from the Oval.