Mod 3 - Additional Cut & Fill

The Cobaki Residential Development site is situated in the coastal lowland in the very N/E of NSW. The site covers the floodplain and residual hinterland to Cobaki Creek (CC) and Cobaki Broadwater (CB), the lower Tweed River Estuary.
The Cobaki ecosystems are of high environmental and indigenous cultural heritage significance, sensitive and complex. i.e. ASS hot spot, layers of coffee rock, organic matter, marine clay and perched water tables.
The systematic unauthorised works on this site over a number of years and particularly in recent years is most concerning. The consequence of some of these works has resulted in significant impacts.
The independent review on 'Geotechnical Engineering, ASS Groundwater (g/w) and Stormwater' (GHD 3/3/09) found there was a lack of "sufficient level of detail and understanding of the ASS conditions and processes (and management thereof)."
I am of the view re the extent of unauthorised works, particularly in the previous 12mths, the site potentially has been considerably compromised and requires further thorough reassessment of ASS conditions and hydrological regime of both g/w and surface water.
The unauthorised works have simply resulted in retrospective approvals and corrective orders.
The unauthorised access track constructed in wetlands in 2013 resulted in the construction of a substantial tidal channel on the site to restore the hydrological regime of tidal inundation of the salt marsh community on the S/W of the site.
Following these events April 2014 it was revealed that extensive earthworks had occurred with the extraction of material from 2 other precincts (estimated at several hundred thousand cubic metres) and placed in the Central Open Space precinct without required approvals.
Despite Tweed having 1 of its driest 12mth period this area of the S/W of the site substantially flooded with the levels continuing to increase from earlier this year now.
This indicates that the unauthorised works has significantly altered hydrological regimes of the site and potentially now being influenced by more than 1 factor.
Potentially g/w flows have also now been altered, exacerbating ASS conditions with potential cumulative impacts to CC and CB from discharge events.
Due to the complexities of estuarine ecosystems, ASS conditions and consequences of subsidence, heaving and contamination, along with the level of unauthorised works, implications for the long term including legalities for future residents and the local authority (and ratepayers) who will be left with the responsibilities of this development must be considered. This is particularly relevant when required approvals were not in place with appropriate assessment not undertaken and required conditions for such works. Hence the need for reassessment of this site and the altered processes of this coastal lowland and impacts on the landscape and soils.

See attached detailed comments from NSW Office of Water and Fisheries NSW

See attached detailed comments from NSW Office of Water and Fisheries NSW

See attached detailed comments from NSW Office of Water and Fisheries NSW

See attached detailed comments from NSW Office of Water and Fisheries NSW