wastewater design

3.0 DESIGN DETERMINATION

We have determined the soil to have the following characteristics

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Soil Characteristics (AS/NZS 1547-2012)

Borehole Nos 5&6

Depth (mm) = 700

Soil Category 5
Indicative Drainage Poor
Structure Strong
Texture Light Clay
Indicative Permeability P (m/day) as Ksa 0.12 - 0.5

For our calculations we have assessed the design flow as follows
Design calculations
Cabins 1 & 2 | Cabins 3 & 4

DLR (mm/day) (Advanced Enviro-septic™ effluent) 5-8 5-8
Hydraulic load (It/day/person) 120 120
Design flow Q (It/day) (equivalent population 4 people) 480 480
Total Trench/Bed Footprint (m’) 60 60
Septic Tank minimum size requirement (It) 3000 3000

 

 

 

Advanced Enviro-septic™ System

 

 

 

Note — 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 120It/person/day (all
wastes). With the installation of standard water reduction fixtures the design flow can be
reduced substantially.

In this instance we have used the DLR rate of 8 mm/day due to the very strongly structured
nature of the loamy Light Clay encountered.

Where the design flow ‘Q’, nominated above, is exceeded the area (Ai) may need to be
increased accordingly. This sewerage system is not suitable for accepting waste from
garbage grinders.

 

Unearthed Geotechnical P/L. 3 Design Report 022-003