Attachment K - HSTP Design

3.0 DESIGN DETERMINATION

We have determined the soil to have the following characteristics

 

Soil Characteristics (AS/NZS 1547/2012)

 

 

 

 

 

 

 

 

Borehole Nos 1 and 2
Depth (mm) 0- 300
Soil Category 3
Indicative Drainage Moderate
Structure High
Texture Loam
Indicative Permeability P (m/day) as Ksat 1.5-3.0

 

For our calculations we have assessed the design flow as follows

 

Design calculations

 

 

 

 

 

 

DIR (mm/day) (Advanced/Secondary quality effluent) 4.0
Hydraulic load (It/day/person) 120
Design flow Q (It/day) (equivalent population 7 people) 840
Design sizing calculation Ai=Q/DIR
= 840/4.0
Disposal Area Ai (m’) =210

 

 

 

 

Fixed Low pressure heavy droplet ‘wobbler’ type (or such) spray irrigation 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 120litres/person/day (all
wastes). With the installation of standard water reduction fixtures the design flow can be
reduced substantially.

Where the design flow ‘Q’, nominated above, is exceeded the area (Ai) will need to be
increased accordingly. On-site sewerage systems are not suitable for accepting waste from
garbage grinders.

 

Unearthed Geotechnical P/L. 3 Design Report 023-038