The Mangrove Mountain landfill is owned and operated by Verde Terra Pty Ltd (Verde Terra). In October 1998, Gosford City Council, now Central Coast Council, granted development consent permitting the remodelling of the Mangrove Mountain Memorial Golf Club, and landfilling activities at the site for that purpose.
Background
In November 2001, we issued an Environment Protection Licence to authorise waste disposal by landfilling at the site.
Since 2012, there have been a series of legal proceedings about the Environment Protection Licence and development consent. In May 2014, landfilling activities at this site were suspended due to legal actions commenced by Gosford City Council.
In August 2018, Verde Terra made applications to vary the Environment Protection Licence and development consent to permit increased landfilling at Mangrove Mountain, which the EPA and Central Coast Council refused. Verde Terra appealed to the Land and Environment Court against the refusals. In June 2024, Verde Terra discontinued both appeals after related legal proceedings found that the development consent did not permit the variations sought.
As part of our commitment to transparency and safeguarding the environment, the EPA is regularly undertaking compliance inspections and is reviewing the Environment Protection Licence to ensure that it provides effective measures to monitor the environmental impact of the site.
We conduct inspections of the landfill to assess the management of water and leachate, including after periods of high or intensive rainfall. The EPA will continue to closely monitor and safeguard against any adverse environmental impact of Mangrove Mountain landfill.
Staff from the EPA and Department of Climate Change, Energy, the Environment and Water (DCCEEW) have conducted sampling of Ourimbah Creek and its tributaries over several years and have not found any adverse impact to water quality from landfill operations. The most recent sampling was conducted by the EPA and DCCEEW in February 2024.
Summary of results
Water quality parameters were generally good with the exception of elevated nitrogen (oxidised and total) and aluminium concentrations at all sampling locations. No semi-volatile organic compounds were detected in any of the water samples. Overall, these results are similar to previous reports.
The aluminium concentrations are likely indicative of background concentrations in creeks of the area rather than pollution. Given the elevated oxidised nitrogen concentrations across all sites, there are likely multiple sources of runoff influencing the nitrogen load in the Ourimbah Creek catchment.
Sample results
Physico-chemical properties and metal concentrations of the water samples collected from Hallards Creek and 3 locations in Stringybark Creek on 6 February 2024.
|
Australian Drinking Water Guidelinea |
Water Quality Default Guideline Valueb |
Hallards Creek |
Stringybark Creek (SB1) |
Stringybark Creek - North (SB2) |
Stringybark Creek - South (SB3) |
|
|---|---|---|---|---|---|---|
|
6 Feb |
6 Feb |
6 Feb |
6 Feb |
|||
|
Temperature °C |
‐ |
‐ |
21.4 |
20.8 |
20.3 |
20.6 |
|
pH |
‐ |
6.5‐8.0c |
7.5 |
7.2 |
6.9 |
6.9 |
|
Conductivity (µS/cm) |
‐ |
125‐2200c |
110 |
160 |
200 |
140 |
|
Turbidity (NTU) |
‐ |
6‐50c,d |
1.6 |
1.9 |
4.6 |
1.1 |
|
Dissolved oxygen (% Sat) |
‐ |
85-110 |
84.5 |
88.7 |
90.9 |
87.3 |
|
Alkalinity (mg/L CaCO3) |
‐ |
- |
11 |
17 |
22 |
13 |
|
Total suspended solids (mg/L) |
‐ |
‐ |
‐ |
‐ |
‐ |
‐ |
|
Metalse(μg/L) |
||||||
|
Aluminium |
‐ |
55 |
70 |
90 |
60 |
100 |
|
Arsenic |
10 |
13 |
< 1 |
< 1 |
< 1 |
< 1 |
|
Boron |
4000 |
940 |
< 100 |
< 100 |
< 100 |
< 100 |
|
Cadmium |
2 |
0.2 |
< 0.1 |
< 0.1 |
< 0.1 |
< 0.1 |
|
Chromium |
50 |
1 |
< 1 |
<1 |
<1 |
<1 |
|
Copper |
2000 |
1.4 |
<0.5 |
0.6 |
<0.5 |
0.7 |
|
Lead |
10 |
3.4 |
<0.1 |
0.1 |
<0.1 |
0.2 |
|
Manganese |
500 |
1900 |
13 |
8 |
7 |
8 |
|
Nickel |
20 |
11 |
< 0.5 |
0.6 |
0.6 |
0.7 |
|
Selenium |
10 |
5f |
< 5 |
< 5 |
< 5 |
< 5 |
|
Silver |
100 |
0.05 |
< 0.1 |
< 0.1 |
< 0.1 |
< 0.1 |
|
Zinc |
‐ |
8 |
1 |
1 |
1 |
2 |
|
External Nutrients (μg/L) |
||||||
|
Ammonia as Ammonia Nitrogen |
‐ |
20c |
<10 |
<10 |
<10 |
10 |
|
Oxidised nitrogen NOx‐N |
‐ |
40c |
110 |
140 |
230 |
120 |
|
Reactive Phosphorus as P |
‐ |
20c |
< 10 |
<10 |
<10 |
<10 |
|
Total Phosphorus as P |
‐ |
25g |
10 |
40 |
30 |
40 |
|
Total Nitrogen as N |
‐ |
350g |
300 |
400 |
600 |
400 |
a Health-based guideline values (NHMRC 2022)
b Freshwater default guideline values for toxicants, for 95% species protection unless otherwise stated (ANZG 2018)
c Default trigger value for south-east Australian lowland rivers (ANZECC/ARMCANZ 2000)
d The units for the default trigger value for turbidity are NTU. This range can be directly compared to results reported in FNU despite the unit difference
e Dissolved metal (<0.45 µm filtered) levels reported unless otherwise stated
f To account for the bioaccumulating nature of this toxicant, it is recommended that the 99% species protection level default guideline value is used for moderately disturbed systems
g Default trigger value for NSW and Vic east flowing coastal rivers (ANZECC/ARMCANZ 2000)