Malabar Headland
Summary of Surface Water and Groundwater Monitoring Data
July 2012
Summary of Surface Water and Groundwater Monitoring Data, Northern Boundary,
Malabar Headland, Malabar NSW
1.
Introduction
Malabar Headland (also known as ANZAC Rifle Range) at Malabar, NSW (hereafter referred
to as the ‘Site’) covers an area of approximately 177 hectares and occupies the peninsula
between Maroubra Bay and Long Bay, approximately 12 km southeast of Sydney CBD. A
large portion of the Site was previously used for landfilling activities prior to the establishment
of a rifle range in the 1990s.
The northern boundary of the Site adjoins the southern end of Maroubra Beach. Areas within
the northern boundary of the Site are often accessed for hiking, dog walking, and other
recreational purposes. Local topography and geology result in surface water and groundwater
flowing towards Maroubra Bay in the vicinity of South Maroubra Beach.
2.
Surface Water and Groundwater Monitoring Data
Surface water and groundwater monitoring has been conducted at the Site since the late 1990s,
with monitoring largely focusing on the northern boundary. The monitoring program has been
undertaken by experienced environmental practitioners, with monitoring and sampling
procedures in accordance with NSW EPA-endorsed guidelines, namely the water quality
criteria given in the Australian and New Zealand Guidelines for Fresh and Marine Water
Quality (ANZECC & ARMCANZ, 2000). These guidelines provide criteria for aquatic
ecosystems (including marine and fresh waters), primary industries, recreational waters and
drinking water. The ANZECC & ARMCANZ guidelines provide ILs for four different levels
of protection for fresh and marine water, namely 99%, 95%, 90% and 80%. These protection
levels signify the percentage of species expected to be protected. Protection levels identified in
the adopted guidelines for the protection of slightly to moderately disturbed ecosystems is
considered the appropriate criteria for the assessment of groundwater and surface water quality
at Malabar Headland. In most cases this protection level refers to the 95% level of protection,
though more conservative criteria have been adopted for certain chemicals in accordance with
the ANZECC & ARMCANZ (2000) guidelines (such instances are indicated in the results
tables presented in Attachment 2).
Attachment 1 shows the surface water and groundwater sampling locations targeted as part of
the ongoing monitoring program. Sample locations MW17 and MW19 as well as NBW01 to
NBW10 represent groundwater monitoring wells. All other locations represent surface water
sample locations. MZ is located in the tidal zone at South Maroubra Beach adjacent to the
discharge point for the stormwater stream that exits the Site and traverses South Maroubra
Beach, and location BK is located in the tidal zone approximately 100 m north of location MZ.
Samples are generally analysed for inorganic and organic chemicals as well as some
microbiological indicator species. Attachment 2 provides a summary of the surface water and
groundwater data collected.
Malabar Headland
Summary of Surface Water and Groundwater Monitoring Data
July 2012
The data collected as part of the monitoring program generally indicates the following about
surface water and groundwater quality along the northern boundary of the Site and at
Maroubra Beach.

Concentrations of dissolved trace metals arsenic, copper, and zinc in both surface water
and groundwater samples often exceed NSW EPA-endorsed guideline criteria for
environmental protection. Concentrations of these trace metals have also been found to
exceed NSW EPA-endorsed criteria in background samples collected further from the Site
at Maroubra Beach (sample BK).

Concentrations of dissolved trace metals chromium and lead have intermittently been
detected above NSW EPA-endorsed criteria, though these occasions are limited and do
not appear to reflect any significant trends.

Ammonia concentrations in surface water and groundwater samples consistently exceed
NSW EPA-endorsed guideline criterion for environmental protection.

Counts of microbiological indicator organisms in surface water and groundwater samples
often exceed NSW EPA-endorsed guideline criteria, though it is generally accepted that
microbiological counts can vary significantly due to a variety of factors (e.g. weather
conditions, season, site use, etc.).

3.
Concentrations of organic chemical species are generally below the laboratory’s limit of
reporting (LOR) and below NSW EPA-endorsed guidelines.
Assessment and Management Strategies
Surface water and groundwater flows along the northern boundary of the Site have been
regularly monitored to better understand and evaluate any potential risks and to manage them
appropriately. Since commencing surface water and groundwater monitoring at the Site, a
variety of assessment and upgrade works have been undertaken. Amongst the tasks that have
been completed or are currently underway:

Construction of a leachate collection pond at the base of the northern batter slope designed
to collect and retain seepage water from the batter slope within the northern boundary;

Construction of a gabion drop structure to better manage surface water and stormwater
flows from the Site, especially during wet weather events;

Construction and maintenance of surface water / stormwater retention ponds and
constructed wetlands within the northern boundary of the site to better manage surface
water flows and migration across the northern boundary of the Site;

Preparation of a human health and environmental risk assessment of surface water and
groundwater flows at the northern boundary in order to better understand the potential
risks to human (beach users, general public) and environmental receptors (aquatic
ecosystems) in the area;

Ongoing monitoring of surface water and groundwater quality along the northern
boundary over the past decade;
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Malabar Headland
Summary of Surface Water and Groundwater Monitoring Data
July 2012

Ongoing monitoring of surface water associated with the Council Drain as historically
contaminant concentrations have been found to be elevated in this drain.

Design (currently underway) of an interceptor trench and associated infrastructure to
reduce groundwater / leachate discharge to the municipal stormwater stream that
discharges from the Site and onto Maroubra Beach;

Structural improvement works including the construction of a rock chute around the
municipal stormwater discharge point to improve flow from the outlet; and

Planning for environmental remediation and management works to improve surface water
and groundwater quality discharging from the Site. Recent works include installation and
monitoring of ten additional groundwater wells
Work continues towards practical and effective remediation and management solutions for
surface water and groundwater quality at the Site.
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Malabar Headland
Summary of Surface Water and Groundwater Monitoring Data
July 2012
Attachment 1 – Surface Water and Groundwater Monitoring Locations
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Malabar Headland
Summary of Surface Water and Groundwater Monitoring Data
July 2012
Attachment 2 – Surface Water and Groundwater Monitoring Data
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