A range of environmental monitoring is conducted at Summerhill Waste Management Centre (SWMC) in an effort to measure any impacts that the operations at the Centre may have on the environment. The type and frequency of monitoring conducted is specified by the Centre’s Environment Protection Licence, which is administered by the NSW Environment Protection Authority (EPA). A copy of this licence (No. 5897) can be viewed on the EPA’s website (select the 'Licences' option and then type '5897' against 'Licence number').
A summary of the monitoring program specified by the Environment Protection Licence is detailed below. Results of recent monitoring are available by accessing the attached links.
A figure detailing the locations of current monitoring points is available in the SWMC Environmental Monitoring Location Master Plan (pdf).
Historical locations can be viewed in the SWMC Historical Environmental Monitoring Locations (pdf).
Summerhill Pollution Incident Response Management Plan (PIRMP)
The purpose of the plan is to guide responses to a pollution incident in an effort to minimise harm to health and environment and ensure reporting and notification obligations are met. Please click on the image below to view the document.
Newcastle City Council established a groundwater monitoring program at SWMC in 1993 to characterise background water quality prior to landfilling and to allow identification of potential impacts on groundwater quality and groundwater levels once landfilling commenced. Groundwater impacts from landfilling would most likely arise from the migration of leachate from within the landfill.
A system of groundwater monitoring bores has been installed in stages as the site has developed. The monitoring program involves collecting groundwater samples from these groundwater wells (when the water is present) four times per annum. Samples are tested for a restricted list of analytes on three occasions and for a more comprehensive list of analytes annually, in accordance with Environment Protection Licence requirements.
The groundwater bore network comprises:
- four monitoring wells around the General Solid Waste (Putrescible) (GSWP) landfill (identified as GW31 to GW35)
- four wells installed around the General Solid Waste (Non-Putrescible) (GSWNP) landfill (identified as GW46 to GW51)
- two wells installed at the former building and demolition waste (FBDW) site (GW34 and GW42).
A number of geotechnical and hydro-geological studies were conducted prior to SWMC being approved. These studies identified the previously mined coal measures underlying the site as the most hydraulically permeable strata in the formations present – although un-fractured coal’s hydraulic conductivity is relatively low. Coal seams beneath the site dip generally to the southeast or southwest.
Thus, in locations downgradient from the landfill, it was attempted to install the groundwater monitoring bore screens in coal seams. Upgradient bores (north of the landfill) are located in areas where the coal outcrop has been mined by open cut methods, so seams are not present. Those bores are screened at depths between 5 and 35 mAHD.
Those initial hydro-geological studies and early groundwater sampling also suggested that groundwater levels beneath the site had been artificially lowered by past mining and mine de-watering activities at the adjacent Gretley Colliery. This meant many potentially downgradient bores were dry.
Those same reports anticipated that groundwater levels may rise when de-watering activities stopped at Gretley, although it was noted that groundwater levels could only rise to the elevation of any discharge points from old workings. Since de-watering ceased at Gretley in 2008, groundwater levels beneath SWMC have not trended upwards, supporting the previous assertion.
A schematic cross-section detailing the geology beneath SWMC and what was considered as the potential rise in groundwater levels - see below. That cross-section was extracted from one of the abovementioned independent reports (CMPS&F, 1997).
Section through Summerhill waste management site and surrounding area
Since commencing groundwater sampling, Council has engaged independent consultants to review the monitoring data and monitoring program on a number of occasions, and has provided those reviews to the NSW EPA. Those reviews have supported the hydro-geological model described above, and have suggested that in many cases, water extracted from bores during sampling represents surface water or condensation pooled within the bores. This is supported by records of static water levels and the variable chemistry of water between bores.
The results of the data reviews are not surprising in view of the previous underground bord and pillar coal mining that took place beneath the site. In bord and pillar mining a regular grid of intersecting tunnels are driven into the coal seams. These tunnels are the bords, and the remnant blocks of coal left between the bords are the pillars. These pillars support the overlying strata during the extraction of the bords, a process known as the first workings. The pillars may be subsequently partially extracted during the second workings, depending on the site. By the end of mining, at least some of the pillars will remain between the voids left from the extraction process. An idealised schematic diagram of bord and pillar extraction from the Encyclopaedia of New Zealand is shown below.
Bord and pillar extraction schematic diagram (Source: Encyclopaedia of New Zealand)
Because of these previous coal extraction techniques, when groundwater monitoring bores are installed at the SWMC site, it is a matter of chance whether the bores intersect remnant pillars of coal or voids left after mining. Bores intersecting pillars are unlikely to encounter groundwater, as that groundwater would follow preferential flow paths in the voids between pillars (intact coal is relatively impermeable). As mine discharge points exist at lower (down-dip) elevations than that of the coal seams beneath the SWMC site, the voids cannot become flooded, and so monitoring bores which intersect voids are also unlikely to encounter groundwater.
Despite the low probability of obtaining meaningful data, SWMC’s Environment Protection Licence still requires groundwater monitoring. Recent results of that monitoring are available on this web site. An analysis of data trends etc is provided in SWMC’s Annual Environmental Report.
A section of the Young Wallsend seam exposed during landfill cell excavations at Summerhill Waste Management Centre. The old workings exposed would have been excavated in the 1880's.
Groundwater annual monitoring results
Groundwater annual monitoring 19-Jul-2017 (pdf)
Groundwater annual monitoring 22-Jul-2016 (pdf)
Groundwater annual monitoring 12-Oct-2015 (pdf)
Groundwater annual monitoring 24-Jul-2014 (pdf)
Groundwater annual monitoring 17-Jun-2013 (pdf)
Groundwater annual monitoring 05-Jun-2012 (pdf)
Groundwater quarterly monitoring results
Groundwater quarterly monitoring 18-Oct-2017 (pdf)
Groundwater quarterly monitoring 05-Apr-2017 (pdf)
Groundwater quarterly monitoring 23-Jan-2017 (pdf)
Groundwater quarterly monitoring 11-Oct-2016 (pdf)
Groundwater quarterly monitoring 04-Apr-2016 (pdf)
Groundwater quarterly monitoring 14-Jan-2016 (pdf)
Groundwater quarterly monitoring 25-Jun-2015 (pdf)
Groundwater quarterly monitoring 18-Dec-2014 (pdf)
Groundwater quarterly monitoring 08-Oct-2014 (pdf)
Groundwater quarterly monitoring 25-Jun-2014 (pdf)
Groundwater quarterly monitoring 12-Feb-2014 (pdf)
Groundwater quarterly monitoring 30-Aug-2013 (pdf)
Groundwater quarterly monitoring 27-Mar-2013 (pdf)
Groundwater quarterly monitoring 18-Dec-2012 (pdf)
Groundwater quarterly monitoring 12-Sep-2012 (pdf)
Groundwater quarterly monitoring 12-Mar-2012 (pdf)
Surface water management
SWMC occupies two adjacent creek valleys comprising the Wentworth Creek and Flaggy Creek catchments. Both creeks flow northwards from the site and discharge into Hexham Swamp. A number of stormwater quality ponds have been established on the natural site drainage lines and all surface water from disturbed areas passes through at least one pond prior to leaving the site.
Factors that have the potential to influence the quality of surface water discharged from the site include rainfall, the amount of disturbed vegetation or ground cover, discharge of groundwater and the escape of leachate from the landfill or leachate management system. Measures employed to prevent impacts on surface water quality due to the operations of the landfill include:
- Screening the types of waste entering the landfill
- Installation of a leachate collection and disposal system
- Diversion of uncontaminated stormwater runoff around the landfill areas to sedimentation ponds
- Daily covering of deposited waste to prevent contact with storm water and minimise leachate generation
- Maintenance of erosion and sedimentation control measures.
Surface water monitoring program
A surface water monitoring program for the SWMC was established on-site in 1991 (prior to the Centre opening) to characterise background water quality prior to landfilling and to assess the potential impacts once landfilling commenced.
The current monitoring program as per condition M2 of the licence includes five sampling locations. Four of these locations are located on the SWMC site and one location is located offsite. These sites are listed below and are presented in the SWMC Environmental Monitoring Location Master Plan (pdf).
- SW55 – Onsite water quality pond downstream of the Former Building and Demolition Waste (FBDW) site
- SW56 – Onsite water quality pond downstream of the General Solid Waste (Putrescible) (GSWP) landfill cells
- SW57 – Onsite water quality pond downstream of the General Solid Waste (Non-Putrescible) (GSWNP) landfill
- SW58 – Offsite point located in Wentworth Creek, upstream of Minmi Road but downstream of SW56
- SW59 - Onsite water quality pond downstream of a non-landfilling section of the site
Surface water flows from the site at SW56 (GSWP landfill catchment), SW55 (FBDW landfill catchment) and SW57 (GSWNP) landfill catchment).
Due to WHS issues associated with access to the off-site sampling location, and residential development between the SWMC and the sampling location, it was determined in consultation with the EPA to defer off-site sampling pending identification of a suitable replacement location.
The current monitoring program involves collecting a sample from each location four times per year when the surface water ponds are discharging water from site. Historically, surface water samples were collected every four months, regardless of whether the ponds were discharging. In June 2009, the decision was made (in consultation with the EPA) to only sample when the ponds were discharging, so that the samples were representative of the water leaving site.
Field observations and field parameters are taken at the time of sample collection. Samples are collected used decontaminated containers and transferred into laboratory supplied sterile bottles. The samples are submitted to a NATA accredited laboratory and tested for the list of analytes required by the site Environment Protection Licence (EPL).
Analysis of sampling data is conducted by independent environmental consultants. Due to a lack of relevant thresholds to compare results against, sampling data is compared against pre-landfilling data where relevant. Known leachate indicating parameters are also compared against levels contained in site leachate to allow identification of any potential leachate impacts. A full discussion of those results is contained in the Annual Environmental Report also prepared by those consultants.
Surface water monitoring results
Surface water quarterly monitoring Oct-2017 (pdf)
Surface water quarterly monitoring Jul-2017 (pdf)
Surface water quarterly monitoring Apr-2017 (pdf)
Surface water quarterly monitoring Jan-2017 (pdf)
Surface water quarterly monitoring 11-Oct-2016 (pdf)
Surface water quarterly monitoring 20-Jul-2016 (pdf)
Surface water quarterly monitoring 03-May-2016 (pdf)
Surface water quarterly monitoring 07-Jan-2016 (pdf)
Surface water quarterly monitoring 24-Dec-2015 (pdf)
Surface water quarterly monitoring 06-Oct-2015 (pdf)
Surface water quarterly monitoring 20-Jul-2015 (pdf)
Surface water quarterly monitoring 03-Feb-2015 (pdf)
Surface water quarterly monitoring 11-Dec-2014 (pdf)
Surface water quarterly monitoring 07-Oct-2014 (pdf)
Surface water quarterly monitoring 24-Jul-2014 (pdf)
Surface water quarterly monitoring 07-Apr-2014 (pdf)
Surface water quarterly monitoring 20-Feb-2014 (pdf)
Surface water quarterly monitoring 12-Nov-2013 (pdf)
Surface water quarterly monitoring 15-Aug-2013 (pdf)
Surface water quarterly monitoring 15-May-2013 (pdf)
Surface water quarterly monitoring 30-Jan-2013 (pdf)
Surface water quarterly monitoring 20-Nov-2012 (pdf)
Surface water quarterly monitoring 06-Aug-2012 (pdf)
Surface water quarterly monitoring 04-May-2012 (pdf)
Surface water quarterly monitoring 12-Mar-2012 (pdf)
Dust deposition monitoring
Dust deposition monitoring is conducted at SWMC in an effort to assess the contribution of site operations to dust fallout in the surrounding area. Dust fallout is measured using dust deposition gauges in accordance with the requirements of the Australian Standard 3580.10.1 – 1991. The dust deposition rate is measured as the amount of dust deposited on a horizontal surface and the units for this parameter are grams per square metre per month (g/m2/month).
Eight dust deposition gauges are located across the site, with another gauge located in the nearby community. The location of the gauges can be viewed on the SWMC Environmental Monitoring Location Master Plan (pdf).
Clean bottles were placed in the dust gauges at the beginning of each month and retrieved within 30 days ± 2 days in accordance with AS3580.10.1 – 1991. The samples were analysed by Council’s Laboratory for total insoluble solids.
The Environment Protection Licence for SWMC does not specify a dust deposition threshold or limit. However, Council has adopted a target of not exceeding an annual average result of 3.9 g/m2/month at each individual location.
This target is based on the NSW EPA annual average target of 4 g/m2/month (Approved Methods for the Modelling and Assessment of Air Pollutants in New South Wales, NSW EPA, 2005).
Dust deposition result
Monthly dust deposition results at each location - past 12 months December 2016 - November 2017
Monthly dust deposition results at each location - past 12 months July 2016 to June 2017
Monthly dust deposition results at each location for 2016
Monthly dust deposition results at each location for 2015
Monthly dust deposition results at each location for 2014 (pdf)
Subsurface gas monitoring
The Subsurface Gas (SSG) monitoring program for SWMC was established to monitor the effectiveness of landfilling operations, particularly waste encapsulation and containment methods. This includes, but is not limited to, the clay capping and revegetation of completed landfill cells.
Landfill gas is the end product of the decomposition of biodegradable waste. Methane, a core component of landfill gas, is a highly potent greenhouse gas having between 21 and 25 times greater global warming potential effect than that of carbon dioxide. It is an odourless, flammable gas at normal atmospheric temperatures and pressures. Carbon dioxide forms the second major component of landfill gas. It is a well-known greenhouse gas, and is an odourless, non-flammable gas normally present in the atmosphere.
The current subsurface gas monitoring program includes five SSG sampling locations. The SWMC Environmental Monitoring Location Master Plan (pdf) shows the locations of these.
Subsurface gas monitoring results
Subsurface gas monitoring 15-Jun-2017
Subsurface gas monitoring 20-Mar-2017
Subsurface gas monitoring 07-Dec-2016
Subsurface gas monitoring 14-Sep-2016
Subsurface gas monitoring 09-Jun-2016 (pdf)
Subsurface gas monitoring 18-Apr-2016 (pdf)
Subsurface gas monitoring 12-Jan-2016 (pdf)
Subsurface gas monitoring 07-Oct-2015 (pdf)
Subsurface gas monitoring 21-May-2015 (pdf)
Subsurface gas monitoring 05-Dec-2014 (pdf)
Subsurface gas monitoring 29-Sep-2014 (pdf)
Subsurface gas monitoring 22-Jul-2014 (pdf)
Subsurface gas monitoring 12-Jun-2014 (pdf)
Subsurface gas monitoring 17-Dec-2013 (pdf)
Subsurface gas monitoring 10-Sep-2013 (pdf)
Subsurface gas monitoring 23-Jul-2013 (pdf)
Subsurface gas monitoring 01-Mar-2013 (pdf)
Subsurface gas monitoring 01-12-2012(pdf)