Dredging for shipping, boating channels and new development, extraction of sand and coral, and the disposal of dredged material threatens the integrity of intertidal and subtidal habitats; endangered species such as dugong and turtle; and the distribution and abundance of fishes. Dredging and spoil disposal may result in increases in the levels of suspended sediments (turbidity) and the rate of sediment deposition. Both these factors influence the distribution and health of seagrass meadows, mangroves, corals and other benthic fauna, and fishes.

FRC Environmental has undertaken a range of dredging-related projects. We provide a detailed and site specific appraisal of the likely impacts of dredging and spoil deposition, based upon an up-to-date scientific appreciation of the tolerances of faunal and floral communities, and inter-relationship of ambient environmental conditions.
Recent projects include:

• Shute Harbour Dredging, Environmental Assessment & Monitoring Program, Whitsunday Shire Council
  
  FRC undertook a comprehensive survey of the seagrasses of the harbour area, and of Shute Bay, within which dredge spoil was to be deposited. Benthic epi- and infauna were sampled using quadrats and cores. FRC also provided an assessment of the resilience of the areas seagrasses and benthic fauna to elevated turbidity and sediment deposition. The fisheries values of the area were assessed through liaison with representative bodies of recreational and commercial fishing, and samples obtained by beam trawl. This baseline data was used by FRC to design and implement a statistically rigorous post-dredging monitoring program.


• Urangan Harbour Maintenance Dredging Program EIS, Hervey Bay; Queensland Department of Transport
  
  The proposed dredging program required an assessment of the impacts of harbour dredging, and an assessment of the options available for spoil disposal. Assessment was undertaken through review, surveys of intertidal and subtidal flora and fauna, and liaison with stakeholder groups including commercial and recreational fishers and conservationists.


• Sediment Sampling and Analysis, Cabbage Tree Creek, Queensland Transport
  
  FRC undertook the pre-dredging sediment sampling and analysis program associated with the proposed dredging of the mouth of Cabbage Tree Creek. This involved field PASS tests, description of sediments, and analysis for heavy metals, TBTs and pesticides.


• Rosslyn Bay Pre-Dredging Sediment Sampling and Ecological Survey, Queensland Transport
  
  Scheduled maintenance dredging of Rosslyn Bay Harbour and entrance channel necessitated the sampling and analysis of sediments to be dredged, and the ecological survey of the proposed spoil site. FRC's Dr John Thorogood designed the ecological survey and led the sediment sampling and ecological field components of this study. The ecological survey (incorporating seagrasses and macroalgae, benthic epi- and infauna and fishes) was designed such that it could serve as the baseline for any future monitoring of the impacts of spoil deposition.


• CityPort Development IAS (aquatic flora and fauna), Trinity Inlet, Cairns; Cairns Port Authority
  
  The CityPort project entailed the major redevelopment and expansion of the Trinity Wharf marina precinct. The project involved dredging for marina basin and access channels, and the construction of marina and wharf facilities. FRC undertook an impact assessment and quantitative baseline studies encompassing fringing mangroves, intertidal and subtidal seagrasses, fishes, and the benthic macrofauna of soft sediments and wharf pilings.


• Harbour Development, Curtis Is. (Gladstone) EIS; Qld Transport
  
  An EIS was undertaken for the proposed development of a boat harbour and barge landing facility. The assessment of impacts of the proposed capital and maintenance dredging on nearby seagrass meadows, coral outcrops and important commercial fisheries was a key component of the study.


• The Management of Dredging and Rehabilitation of Dredged Sites within the Brisbane River; Brisbane River Management Group
  
  Looking to the cessation of dredging in the river, the BRMG commissioned studies to consider ways to minimise the environmental impacts of dredging, and to optimise rehabilitation of sites once dredging ceases. FRC considered the relative environmental impacts of available dredging technologies, the impacts of long-term dredging operations on the rivers flora and fauna, and provided recommendations relating to habitat rehabilitation.


• Toondah Harbour Redevelopment Environmental Study, Redland Shire Council
  
  The proposed redevelopment of Toondah Harbour, including the enlargement of the existing swing basin and associated navigation channels, required a detailed assessment of the likely impacts of dredging, and the consideration of a range of options for spoil disposal. The impacts of spoil disposal on an adjacent mangrove site in 1990 were also assessed.


• Aquatic Ecosystems Assessment, Bay Islands Water Supply Project; Redland Shire Council
  
  To lay mains pressure water pipeline between the southern bay islands, trenches needed to be dug in the intertidal and shallow subtidal . The impacts of habitat disturbance, increased turbidity, spoil stockpiling and spoil replacement associated with this work were assessed. Particular attention was paid to mangrove and seagrass ecosystems, and to the impacts of resuspended sediments and acidification related to spoil stockpiling. Following completion of the works FRC designed and implemented an environmental monitoring program to document the natural recovery of these communities.


• Pioneer River Sand and Gravel Extraction Management Study (aquatic ecology), Mackay; Dept. Natural Resources
  
  Following a review of the literature, liaison with stakeholders, and a survey of the tidal reaches of the river, this study considered the impacts of current extractive operations on the aquatic and riparian flora and fauna of the Pioneer River, and provided advice regarding the environmental management of future operations.


• Ecological Monitoring of Kirra Reef, Gold Coast; NSW Dept. Public Works
  
  FRC was responsible for the design and implementation of ecological baseline studies and a monitoring program to assess the impacts of beach nourishment (disposal of dredge spoil from the Tweed bar), on adjacent rocky reefs. The studies considered the impacts of sediment deposition and elevated turbidity on the benthic flora and fauna of the sites rocky reefs (including hard and soft corals); and on the areas fish fauna.


• Ecological Monitoring of Kirra Reef, Gold Coast; NSW Dept. Public Works
  
  FRC was responsible for the design and implementation of ecological baseline studies and a monitoring program to assess the impacts of beach nourishment (disposal of dredge spoil from the Tweed bar), on adjacent rocky reefs. The studies considered the impacts of sediment deposition and elevated turbidity on the benthic flora and fauna of the sites rocky reefs (including hard and soft corals); and on the areas fish fauna.


• Assessment of Coastal Ecology & Acid Sulphate Soils; Prouds Landing Development, Gold Coast
  
  This project involved the assessment of proposed channel deepening within the Gold Coast waterways. Impacts on adjoining mangroves and the areas fisheries were principal considerations. The disposal of acid-sulphate potential spoil was also addressed.


• Proposed Coral Dredging at Green Is., Moreton Bay (EIA); Queensland Cement Limited
  
  The proposed dredging of sub-fossil coral from Green Is., Moreton Bay was a major environmental issue for the adjoining City of Brisbane. As part of a multi-disciplinary team, FRC studied the impacts of the dredging on the adjacent mangrove, seagrass and algal flora; intertidal and subtidal benthic in- and epi-fauna; coral communities and fishes. FRC also contributed to an Environmental Management Plan and Monitoring Program, which included scope of studies and cost estimates.


• Development of a Coastal Environmental Monitoring Program, Weipa; Comalco Aluminium Ltd.
  
  FRC co-ordinated a multi-disciplinary team in a review of Comalcos existing coastal environmental studies, and in the preliminary development of a cost effective and defensible environmental monitoring program for the Embley and Mission River estuaries. The impacts that were considered included: the effects of dredging, port activities, and mine run off on physical and chemical aspects of water quality and sediment deposition rates; and the contamination of shellfish by heavy metals, hydrocarbons, and sewage effluent. Critical habitats and ecosystems that were considered included: intertidal and subtidal seagrass meadows; fringing mangrove forest; benthic epi- and infauna; and fishes and crustacea of commercial and recreational importance. Integral components of the study were an assessment of the ongoing need for monitoring; development of appropriate terms of reference; and cost estimates.


• Inter-Island Development Project, Kiribati; AIDAB
  
  The project involved the establishment of a base line study for ongoing environmental monitoring and impact assessment of the marine environment of Tarawa Atoll relating to coastal engineering works, including extensive channel and harbour dredging. Sub-components of the study related to artisanal and commercial fisheries, seaweed culture, bivalve mollusc harvesting, and seagrass, mangrove, and reefal habitats. An integral component of the studies included the development of ongoing monitoring requirements and associated cost estimates.