Attachment K - HSTP Design

Garbage grinders are not suitable for on-site domestic wastewater treatment plants as
their use introduces large amounts of additional solid matter, which must be broken
down by the system. Their use also greatly increases the hydraulic load.

All wastewater treatment plants/systems work less efficiently when overloaded with
solid wastes. All reasonable and necessary actions and efforts to restrict the flow of
solid wastes, particularly from the kitchen, shall be encouraged and employed by all
present and future owners/ occupiers/users of this Land Application Facility.

A baffled grease interceptor trap on the kitchen waste supply line is a valuable
addition to any wastewater treatment system. If installed/recommended this will, with
effective maintenance, limit the amount of grease, fats and other solid matter from the
kitchen that enters the Land Application Facility.

The choice of cleaning products will influence the environmental impact of
greywater and, equally, will influence the overall performance of treatment
within the treatment plant. Only genuine biodegradable products and products
with low phosphorus should be used. Common washing powders contain sodium
salts as bulking agents which produces a saline greywater. Powdered products
which use potassium salts or liquid concentrates produce better quality
greywater. Some detergents and powder cleansers contain boron which not only
can be toxic to plants in high concentrations but can also be toxic to animals.

Operation

This Land Application Facility shall be used only for effluent application and not used
for purposes that compromise the effectiveness of the system or access for future
maintenance purposes.

In order to reduce sludge build-up in the tank never dispose of used cooking oil
grease/fats or food scraps or similar material down the sink.

Do not allow newspapers, disposable or sanitary napkins, rubber products, nappy
liners, cotton buds etc. to enter the system. The use of better quality toilet paper can
also help in improving operation of the system.

Do not allow excessive quantities of disinfectant liquids, bactericides, antiseptics,
strong caustics, acids, alkalis or chemical detergents to enter the wastewater system.
Their use can severely affect the bacterial, biological and chemical processes within
the system. Minimise their use and use more environmentally friendly products.

Where possible, the owners/householders/users should avoid shock loading of the
system, for example, by staggering the hours that the washing machine is used, and
the peak times in the bathroom. Washing machines should be used where possible
throughout the week instead of several loads within one day.

 

Unearthed Geotechnical P/L. 14 Design Report 023-038