Attachment K - HSTP Design

Maintenance

The grasses/shrubs used in conjunction with any Land Application Area should be
kept well mowed/pruned to ensure that these plantings take up nutrients with
maximum efficiency.

Grease interceptor traps if installed must be pumped out/cleaned periodically or as
necessary. The frequency of service is dependant on its use and on the build up of
greases and fats within the trap.

Septic tanks and or primary tanks/chambers for wastewater treatment plants reduce
solids by bacterial deposition. Consequently, sludge settles at the bottom of the tank
and a scum or crust forms at the liquid surface. Periodic checks are necessary (eg
annually depending on the load entering the system), to ensure that no carry-over of
solid matter is entering the Land Application Area. It may well be a number of years
before the sludge level rises to a level (when scum and sludge occupy 2/3rds the
volume of the tank or fist stage of a two-stage system), which is detrimental. This is
seldom less than three (3) years (depending on the load imposed on the system and the
size of the septic tank or primary tank/chamber). Under normal circumstances,
desludging of a septic tank should be performed every three to five (3-5) years. If
existing septic tanks are to be incorporated they shall be fitted with outlet filters, and
must also be pumped out before commissioning of the system. All manufacturer
maintenance/service requirements are to be met.

Filters

An effective filtration system for all wastewater treatment systems is essential. The
type required will depend on the type of system installed and the quality of the water
to be filtered. The size of the system will also determine which filter system would be
appropriate. In recent years, effluent filters have been added to the septic tank outlet
baffle to limit carry over of solids. All filters shall be cleaned at regular intervals (eg.
every six months or more often if and as necessary). Media, screen or disc filters can
be used depending on water quality. The filter shall be installed as far down the main
supply line as practical. This is an insurance policy, in case a break occurs in the
main line, or solids coagulate/form on the pipe walls and strip off in larger formations,
which may cause blockages.

 

Unearthed Geotechnical P/L. 15 Design Report 023-038