Effluent Disposal Report

In this instance the existing vegetation, extending more than 30m downslope of the
proposed Land Application Area may be deemed to be satisfactory as the
recommended transpiration buffer zone.

It is essential that all associated stormwater flows from this and neighbouring
allotments, driveways, roads, tanks and roofs are diverted away and well clear of the
proposed Land Application Area by proper final grade of the finished surface.

We recommend the base of the entire excavation and the existing ground
immediately downslope of the AES trench (approximately 1m) shall be ripped, along
the contour and parallel to the lay of pipes, to a depth of 200mm prior to the
construction of the AES installation, whilst adding dolomite/gypsum at nominal rate
of 0.5 kg/sqm.

During the excavation processes we recommend separation of the grey/brown topsoil
(to be spread over the top of the entire installation to facilitate grass growth) from the
orange/brown/grey subsoil which is used to backfill the sand bed.

We further recommend a minimum depth of cover at the low side of the sand bed
extension of 300mm.

5.2 Planting Regime

Plantings improve the efficiency of the system with the uptake of nutrient and natural
transpiration processes. Further qualified advice from local nurserymen and the local
regulatory authority should be preférred when choosing plants that may be more or
less suitable or acceptable to your region. Grasses should be kept well mown and
raked for better evaporative and transpiration processes (avoid throwing grass
clippings onto the Land Application Area). Shrubs should be kept well pruned for
better evaporative and transpiration processes. Endemic vegetation must be retained
and/or reinstated.

Following the site preparation, installation and pre-commissioning tests the Land
Application Area shall be allowed to revegetate with sufficient appropriate shallow
rooting grasses.

Unearthed Geotechnical P/L recommends further assessment regarding planting
requirements be sought prior to, or at the time of installation of the Land Application
Facility. It may be necessary to implement an additional planting regime.

Do not plant shrubs or trees within the surface water diversion drains, as these drains
need to be kept free of obstruction and trash for maximum diversion efficiency.

We recommend the application of dolomite/gypsum at a nominal rate (say 0.5
kg/sqm) to the entire basal area, when preparing the existing soil. This will assist with
both plant growth and/or pH control. Further applications may be required during the
serviceable life of the Land Application Area.

 

Unearthed Geotechnical P/L. 10 Design Report 020-212