No of
bedrooms
No of
Users
Water
consumption
L/day
Sandy
Loam
0.6m/d
Loam
0.3m/d
Clay
loam
0.2m/d
Silty clay
0.06m/d
2
4
360
24
30
35
60
2
4
480
32
40
47
80
3
6
540
36
45
53
90
3
6
720
48
60
71
120
4
8
720
48
60
71
120
4
8
960
64
80
94
160
Construction Notes

1) Sizing

Length of Trench in metres for the number of bedrooms
Water consumption and soil type

The Niimi Absorbtion trench system

Less than 2 bedrooms (4 people) or more than 4 bedrooms requires
specific design and approval from relevant authority.

The lower water consumption figure may be used only where water-
efficient appliances are installed within the dwelling.


2) Liner- Heavy duty polyethylene 0.2mm thick.


3) Medium - The coarse gravel should be inert with surface area for protozoan slime to grow on. Other inert materials such as shells,
plastic, etc. are also suitable.

4) Water Table - Not less than 1.3m below ground surface level, however, if less than this site may still be suitable.

5) Sandy soils or clay soils require specific design and approval from relevant authority.

6) The size of greywater tank shall conform to be requirements of AS1546 and AS1547.

Drawing Notes

1) Width and depth of trenches may be varied to suit conditions, but should have roughly the same cross-sectional area as shown.

2) Normally there is one trench in use while the other is resting.

3) Mesh is used to keep organic soil out of the coarse gravel.

4) Spacing of slots in the distribution pipes is varied to ensure an even distribution of effluent.

Maintenance

1) An accredited person must certify to Council, one year after installation and every three years thereafter, that the system is functioning correctly.

Environmental Management Pty Ltd revised Dwg 30/5/94

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