wastewater design · MCU22/0192

5.2 Installation Notes.
Future Shed.

All installation works, components and fittings must comply with AS/NZS 1547-—
2012 On-site Domestic Wastewater Management, and the Queensland Plumbing and
Wastewater Code, and the local authority.

Soils are susceptible to damage during the construction and installation processes.
The natural integrity of the existing soil conditions of the Land Application Area must
be preserved at all stages of the proposed development. Damage to the existing soil
profile must be avoided. Do not over work the soil profile. This facility must not be
constructed or installed during or immediately after periods of wet weather.

When excavating the trenches/beds excavate in small bites using a bucket fitted with
ripper teeth to preserve the permeability characteristics of the natural soil.
Scarify/rake all smeared excavated surfaces.

Particular care should be taken with the layout and construction of supply line
trenching/pipework, as with all drainage, plumbing and electrical trenches to inhibit
surface water infiltration along and into the Land Application Area. All supply line
excavations and trenching shall be backfilled with interceptors.

Particular care should also be taken with the layout and construction of the Land
Application Area trenching/pipework so that released effluent cannot travel back
along trenching causing excessive soil moisture in some areas.

As with all effluent disposal in Land Application Areas, the release of effluent along
the contours (i.e. level) is both elementary and critical to achieve efficient spread and
even disposal. The trenches/beds must be constructed level.

Correct pipe layout and Land Application Area construction/installation is an essential
part of our recommendations and design. If the site is not prepared in accordance
with our design, or is prepared inadequately or is prepared poorly, inefficiencies may
occur and we do not take responsibility for the consequences in such cases and we
will make an additional charge if as a result, more testing, re-designing or re-writing
of the report is necessary.

As with all use of sand or distribution aggregate for wastewater treatment and disposal
it is very important to restrict the ingress of finer particles to maintain the integrity of
the expected performance outcomes of the sand or distribution aggregate. To this end
Unearthed Geotechnical P/L recommends the entire bed of sand or distribution
aggregate be covered in an appropriate and approved geotextile fabric to restrict such
ingress of finer soil particles. This will help to maintain the expected performance
outcomes of the sand or distribution aggregate. Without the use of an appropriate and
approved geotextile fabric it is probable that the integrity of the sand or distribution
aggregate will likely be compromised.

We recommend the installation of a three-way baffled/wiered distribution box
(installed level on a 0.9 x 0.9 x 0.1m concrete pad) to achieve a non-biased (equal)

 

Unearthed Geotechnical P/L. 13 Design Report 022-164