wastewater design · MCU22/0192

4.1 Limitations.

Our site and soil evaluation noted the following limitations which may have an
adverse effect on the performance, serviceability, and sustainability of
environmentally acceptable on-site domestic wastewater management

« allotment size, configuration and topographic idiosyncrasies,

e separation distance requirements,

« areas of excessive slope,

° areas previously used or required for construction or landscaping,

e poor permeability of sub soil profile.

In formulating our recommendations we have noted, considered and made allowance
for the effect these limitations will have on the performance, serviceability, and
sustainability of on-site domestic wastewater management. We consider that in line
with the recommendations set out within this report, and with appropriate control
measures in position, sustainable on-site domestic wastewater treatment and disposal
will be achieved.

In consideration of these limitations and with reference to the Queensland Plumbing
and Wastewater Code and AS/NZS1547-2012 On-site Domestic Wastewater
Management, and with presumed compliance to the recommendations made in this
report, for the Proposed Cabins we recommend advanced secondary treatment of all
domestic wastewater flows for the efficient, sustainable and environmentally
acceptable disposal of treated effluent. The use of such approved systems
consequentially enables the 30m horizontal separation distance from the intermittent
watercourses/dams to be reduced to 10m, and the vertical separation distance to be
reduced to 300mm.

In consideration of these limitations and with reference to the Queensland Plumbing
and Wastewater Code and AS/NZS1547-2012 On-site Domestic Wastewater
Management, and with presumed compliance to the recommendations made in this
report, for the Future Shed we recommend primary treatment of all wastewater
flows for the efficient, sustainable and environmentally acceptable conventional
absorption trench/bed disposal of the treated effluent.

Although we recorded no existing evidence of eutrification, we believe there is the
potential for eutrification of any associated dam or watercourse if there is nutrient
leakage from any disposal site. However, with the encouraged use of phosphate free
cleaning products, we believe the reduced potential will be contained.

Given the recorded slope may be viewed as a site constraint we recommend the
installation of retention mounds/bunds (suggested minimum 1000mm wide and
150mm high) running across the slope to help with the confinement and retention of
the applied effluent with the proposed Land Application Areas.

 

Unearthed Geotechnical P/L. 6 Design Report 022-164