wastewater design · MCU22/0192

OPERATION AND MAINTENANCE GUIDELINES

General

The purpose of these guidelines is to provide guidance to homeowners and operators
on maintaining a Land Application Facility in an unsewered area. The focus of these
guidelines is the facilitation of sustainable on-site disposal of treated effluent without
compromising public health or the quality of the environment.

The amount of wastewater to be treated is a major design factor in wastewater
treatment systems. Exceeding the design flow will contribute to failure. Water
conservation will reduce the volume of effluent requiring disposal to the Land
Application Area, which will increase its serviceable life and improve its efficiency.

Conservation measures include

e employing careful water use habits,

e installing flow/pressure valves on all water outlets,

e having leaking taps repaired immediately,

e — only using dish washers when there is a full load,

e avoiding overloading the system by spacing out water use as evenly as possible,
e installing reduced flush (6/3 litre preferred) water closets,

e installing water conserving automatic washing machines, and

e shower-flow restrictors and aerator faucets.

AS/NZS 1547-2012 (Appendix H, Table H1) lists the typical wastewater design flow
allowance for households with an on-site roof water tank supply as 120-
litres/person/day (all wastes). With the installation of standard water reduction
fixtures the design flow can be reduced substantially.

Efficient on-site sewerage treatment relies on a balanced combination of physical,
biological (bacterial) and chemical processes. In order to keep bacteria working
efficiently in the tank/plant and the Land Application Area

restrict the amount of solid wastes entering the system,

use biodegradable soaps, cleaning products with low phosphorus/ nitrogen levels,
use low-phosphorus and low-sodium detergents,

use detergents in recommended quantities,

do not use powerful bleaches, whiteners, nappy soakers, spot removers, and

do not put chemicals, disinfectants, oils or paint down the drain.

 

Unearthed Geotechnical P/L. 19 Design Report 022-164