Water Quality Monitoring Project

Project Overview

Gold Coast Waterways Authority (GCWA) commissioned to the preparation of the Dredge Material Management and Placement Plan and the Biggera Creek Dredging Yellow Zone Management Plan. These documents address the design, approval process, permit requirements and environmental management associated with dredging activities within Biggera Creek.  Biggera Creek is located in Biggera Waters on the Gold Coast, QLD. The creek joins the Broadwater and is situated north-west of Wave Break Island and the Gold Coast Seaway. The creek is surrounded by high density residential development, with a large portion of the houses adjoining the creek having established pontoons for private use. The purpose of dredging Biggera Creek is to maintain navigational access, with subsequent dredged material to provide foreshore nourishment for recreational amenity and to assist with mitigating shoreline erosion. 

Our Role

Ecobalance was commissioned to undertake water quality monitoring activities including: 

  • Set up and install water quality monitoring devices.
  • Program the water quality instruments to record turbidity levels at 15 min intervals.  Performance criteria to be applied as outlined in the permit includes: 48 hour daily mean values must not exceed the long-term baseline 99th percentile (i.e. in accordance with the Ecosystem Health Monitoring Program (EHMP) Queensland Waterways Database and supplemented water quality data if available); 14 day rolling daily mean values must not exceed the long-term baseline 80th percentile unless the equivalent background value is also exceeding the baseline percentile over the same period of time. 
  • Program the water quality instruments to record pH levels at 15 min intervals.  Performance criteria to be applied as outlined in the permit includes: Daily mean ph values to be between 6.5 and 8.5 units.
  • Analysis water quality data and prepare report.

Outcomes

A number of recommendations were developed for future water quality monitoring programs including: collecting turbidity data directly prior to the dredging activity and that turbidity levels monitored during dredging are assessed every 48 hours and used to guide dredging stand-by times.  The use of turbidity curtains or silt curtains could also be considered to assist with localising the impacts of turbidity pluming. Conducting a seagrass health and GIS mapping assessment could also validate potential impacts from dredging on surrounding seagrass habitat.  

Location

Biggera Waters, Gold Coast, Australia.

Client

Sandpiper Dredging Pty Ltd.

Expertise