Fremantle Port Inner Harbour and Channel ... - Fremantle Ports

5. Monitoring Process, Schedule and Contingency
Management Measures
5.1. Water Quality
Water quality monitoring and management response triggers provide a mechanism to
manage impacts to environmental, recreational and aesthetic values associated with water
quality and provide an early warning of potential impacts.
5.1.1. Ecosystem Health Values
LAC monitoring for Seagrass and Coral Health
Frequency
• Continuous logging (every 15 minutes) of light starting one week prior to dredging
(baseline) and then until completion of dredging and disposal.
Recorded light data will be downloaded from loggers each fortnight.
Location
• Twenty-six locations overlying seagrass and two locations overlying coral (plus one
site in Rocky Bay for contextual purposes) as detailed in Sections 3.1, 3.6 and
Figure 3.1.
• Monitoring will be targeted and focussed on data collection at those sites within
proximity of the visible plume/s (as based on field observation and aerial imagery),
which technically defines the potential zone of influence, plus associated reference
sites. That is, not all sites will be sampled for the full duration of the dredge program
and when dredging, only those sites within the proximity of the visible dredge,
disposal and/or return water plumes will be sampled, plus associated reference sites.
Method
• Calculate LAC from underwater light intensity measured by two light loggers deployed
at each location with at least 2 m of vertical separation.
• LAC will be processed for each location (within 72 hours from collection of all light
loggers) and presented as a 14-day rolling median.
• For contextual purposes TSS concentration will also be determined at each location by
collection of a single integrated-depth water sample, sent to a NATA-accredited
laboratory for analysis of the concentration and determination of the organic
component via loss on ignition (LOI).
• For contextual purposes a profile of turbidity (NTU) will also be measured at each
location.
• For contextual purposes, temperature loggers will be deployed at both coral
monitoring sites, for fortnightly download.
• Median LAC will be compared to LAC triggers described in Section 4.1.1 – Light
requirements for Seagrass and Coral Health, to determine the appropriate
management response as listed below.
Contingency Management Measures
No exceedance
• Where LAC is determined to be below “No exceedance” trigger levels at seagrass and
coral health monitoring sites, the lack of exceedance will be noted in fortnightly
reporting (by the Environmental Monitoring Contractor) to Fremantle Ports and the
Office of the EPA.
Regional exceedance
• Where LAC is determined to be above the “No exceedance” trigger levels at seagrass
and coral health monitoring sites, exceedances in the first instance will be investigated
to determine whether the dredging and spoil disposal activities were responsible
(wholly or in part) for observed elevations of turbidity. Investigations of possible
causes will examine:
o
o
Whether any similar trends were observed at reference sites;
The location of the dredging and spoil disposal activities in relation to the
affected site(s);
Oceanica: Fremantle Ports: Inner Harbour and Channel Deepening - Water Quality Monitoring Program 19