Attachment D - Stormwater and Water Quality report

                                                                                Callaghan & Toth


3.0 DESCRIPTION
The site currently consists of two lots, with Lot 5 SP213104 containing the Cooroora
Woodworkers Club building, the Lower Mill site building and the Cooroy Camphor Laurel Club
building. There are hardstand areas associated with these buildings including pathways, formal
and informal carparking areas, access driveways and garden areas.

Lot 7 SP173771 is the Cooroy Creek bushland Reserve and is mostly vegetated with riparian
vegetation along Cooroy Creek. Lot 7 also contains a gravel access driveway and turnaround
area which is an informal carparking area during events. The existing biobasin is located within
Lot 7 and is contained within a drainage easement. This biobasin was constructed when the
Lot Reconfiguration of the Lower Mill site occurred. It is in need of refurbishment as its design
is no longer to current best practice design standards.

The sites are bounded by Cooroy Creek to the south, east and north-east and Lower Mill Road
to the west and Lot 4 SP173771 to the north – an industrial site.


3.1      Contaminated Land:

During previous development of the site, contaminated land issues have been addressed by
Council and managed in accordance with Site Management Plans (SMP).

It is our understanding that the current approved Site Management Plan dated 28 April 2008
(EPA File: 902326) for Lot 5 SP173771, Lot 7 SP173771, Lot 2 RP47020 and Lot 1 RP87371
(See Appendix B) is still current for management of the site.

These lots were part of the Boral Cooroy timber mill which operated from 1959 to 2001.
Previous contaminated land investigation identified a number of areas of contamination which
were treated and/or capped. Residual soil impact in locations F2 and F3 exceeded QLD EPA
EILS for arsenic, copper and chromium (III). Soil remediation works undertaken on Lot 7 in the
year 2000 included capping the area with 500mm clay layer. This clay capping layer had a
confirmed density ratio of 95.5%. This capping layer was covered by 100m of clean soil. One
of the capped areas on Lot 7 is under part of the proposed new carpark.

The SMP states:

The existing capping is to remain in place, undisturbed, other than for the construction of
service trenches. In the event that the existing capping layers are disturbed or removed, a new
capping layer, or equal of better standard and designed to achieve the objectives of this SMP, is
to be installed.

Depending on the detailed design levels of the new carpark there is potential requirements for
excavation works to construct this carpark. The new swales may also require excavation which
needs to be managed in relation to the capped contaminated material areas on Lot 7. As such
the SMP states:

Any soil excavated on the site must be assessed for contaminants of concern to determine if
material is contaminated and to identify appropriate management and disposal/re-use options.




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2001 Lower Mill Carpark Extension SWMP                                       February 2020