Attachment D - Stormwater and Water Quality report

layer were covered by either 100mm of road base (trafficable areas) or clean soil (non-
trafficable areas).

Metal concentrations in excess of Qld EPA EILs also exist in the vicinity of the former
sawdust shed. This area has maximum concentrations of 101mg/kg for arsenic (also
above HIL “A” guidelines), 92mg/kg for copper, and 142mg/kg for chromium (II). All
impact was detected in soil samples collected at shallow depth (0-200mm) in fill
material present in this area of the lot, however the impact has not been vertically
delineated in some locations.

2.0 OBJECTIVES OF THE SMP
The purpose of this SMP is to manage contaminated soils and materials on the lots in a

manner that protects human health and the environment. This objective will be achieved
through the following processes.

° Monitoring and control of all intrusive site works including excavations,
trenching, drilling and scraping.
° The placement and maintenance of landscaping and capping layers which will

provide barriers to occupiers of the site and the general public from the
contamination, as well as restricting erosion and water infiltration and the
potential for residual impact to migrate via leaching processes.

° The application of maintenance and monitoring requirements for the capping
layers.

3.0 ACHIEVEMENT AND MAINTENANCE OF OBJECTIVES

3.1 Responsibility.

The owner of the land (as defined in the Environmental Protection Act 1994) is to
ensure that this SMP and any variations approved or required by the administering
authority are complied with in order to achieve the objectives. The obligations and
conditions set out in this SMP bind the owner of the land.

3.2. Provision of SMP to appropriate persons. The owner must provide all persons
involved in building design and planning and all contractors and lessees conducting
building and/or excavation works with a copy of the SMP prior to commencement of
site works. All persons occupying or working on the site must comply with the
requirements of the SMP.

3.3 Site Capping.

3.3.1 Existing Capping. 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, of equal or better standard and
designed to achieve the objectives of this SMP, is to be installed.

The capping layer must consist of 500mm of compacted clay and/or other equivalent
low permeability (less than 1x10” m/s) cover, and is to be installed within areas as
outlined in Figures 2 — 5 (attached) to maintain a barrier between the residual
contamination and site users. The capping layer is to be maintained in sound condition
at all times. If vegetation is to be placed over the capping layer, a minimum thickness of