wastewater design

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,

installation of water conservation fittings,

installing low-flush toilets where appropriate,

taking showers instead of baths,

installing small/efficient shower roses,

purchasing washing machines with economy water cycles,
having leaking taps repaired immediately,

only using the dishwasher when there is a full load,

only washing clothes when there is a full load, and

avoid overloading the system by spacing out water use as evenly as possible.

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-lt/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 the bacteria working
efficiently in the tank and in the land-application area:

e use biodegradable soaps and low-phosphorus detergents,

use biodegradable cleaning products with low phosphorus and nitrogen levels,
use low-sodium detergent in dispersive soil areas,

use detergents in recommended quantities,

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

do not put chemicals, chlorine, water softeners or paint down the drain, and

do not put vegetables, meats, fats, oils coffee, citrus, cigarettes or medicines
down the drain.

 

Unearthed Geotechnical P/L. 14 Design Report 022-003