Appendix E - Wastewater Report

                             PROPOSED RESIDENTIAL SUBDIVISION
                             9A JIRRIMA CRESCENT, COOROIBAH



Executive Summary
This report details the results of a geo-environmental investigation undertaken to address the feasibility of
on-site effluent disposal for a proposed 1 into 2 lot residential subdivision of Lot 101 on SP168341, located at
9A Jirrama Crescent, Cooroibah. The investigation was performed by Tectonic for Maud Cazot. Murray &
Associates (Qld) Pty Ltd are the town planners for the project.

The existing property covers an area of approximately 4.5 ha and is zoned rural residential under the Noosa
Plan 2020. Proposed development will comprise the separation of the existing house and land situated on
the eastern half of the site from vacant land in the western half of the site to form two new land parcels
(numbered Lots 1 and 2).

Site investigation comprised a walk-over by an experienced environmental scientist and drilling of one hand
augured borehole at the proposed wastewater land application area. Subsurface conditions encountered in
HA1 comprised stiff clayey silt to 0.3 m below ground level (BGL), overlying very stiff silty clay to borehole
termination at 1.5 m BGL. Groundwater was not encountered.
Topography across the site is consistent with relatively flat and gentle slopes, where present. Available
areas for effluent disposal have been categorised as Linear Planar, with a subsurface soil profile equivalent
to Medium to Heavy Clays (Soil Category 6).
Having consideration for the terrain-soil assessment and environmental constraints of the site it is
recommended that wastewater from the proposed lots be directed to suitably sized Household Sewage
Treatment Plants (HSTPs) connected to a shallow subsurface or surface irrigation systems. The
HSTPs must be licensed to produce at least Secondary standard effluent.
Considering the site and soil conditions across the proposed development areas, a surface or shallow
subsurface irrigation area of about 360 m² would be required for proposed Lot 1. Sufficient room to site the
wastewater irrigation areas with the necessary setbacks is available for both proposed lots. Final irrigation
area and detailed wastewater system design will be dependent upon individual site assessment at the building
stage.
An existing wastewater treatment system and surface irrigated land application area was identified on the
southern side of the existing residence on Lot 2. No evidence of malfunction or failure was noted during site
inspection. As there are no alterations to the existing dwelling proposed, and both the existing dwelling and
associated wastewater treatment system are entirely located within the bounds of proposed Lot 2, this
system is considered suitable to continue to service the existing dwelling.




4 November 2020
Report No. 20333-001-Rev0                              ii