wastewater design

Maintenance.

The plants and grasses used in conjunction with any Land Application Area should be
kept well pruned, mowed and raked to ensure that these plantings take up nutrients
with maximum efficiency. Grass cuttings should not be allowed to accumulate over
the Land Application Area.

Septic tanks 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 sludge (or crust) is entering the trenching (disposal system), thereby
inhibiting its usefulness. If the sludge depth in the bottom of the tank is 300mm or
less from the bottom of the outlet, then it is time to have the septic tank desludged (i.e.
emptied). 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 of course on the load entering the system). 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. The grease interceptor
trap (if fitted) must also be cleaned out on a regular basis or as required — dependent
upon the load. All manufacturer maintenance/service requirements are to be met.

 

Unearthed Geotechnical P/L. 16 Design Report 022-003