The tank parameters must be configured to represent the total number of dwellings in downstream Average or Behavioural Water Use nodes. For example, 4 houses with 10 m3 of tank volume each would need to be attached to a single tank node with 40 m3 total volume.
Figure 1. Urban Developer storage tank definition.
VDetention is the Detention Storage Volume (m³);
VRetention is the Retention Storage Volume (m³);
VDead is the Dead Storage Volume (m³);
hoff-taker is the height of the supply off-take obvert from the base of the tank (m);
hretention is the height of the retention storage volume (m);
hdetention is the height of the detention storage volume (m);
htank is the height of the storage tank (m);
hTT On is the height of the trickle top-up on trigger (m); and
hTT Off is the height of the trickle top-up off trigger (m).
Defines the cross-sectional area of the tank base.
Defines the total height of the tank. Includes detention and dead zone height
Height of off-take invert
Defines the height of the offtake pipe on the tank; the offtake pipe supplies demands from the tank.
The invert level of the offtake is the height of the lowest point of the pipe above the tank base. Once the tank is filled above the offtake invert level, the water depth in the tank will never fall below this level.
Demand off-take occurs from the base of the tank just above the anaerobic or "dead" zone; a tank should therefore have a minimum "dead zone" depth of 0.1 m to allow for accumulation of sediment and other material. Water will never be drawn from the "dead zone".
Initial water depth
Defines the initial depth of water in the tank at the start of the model run.
Detention volume depth
Defines the detention (storage) volume depth of the tank. The detention volume depth is the depth from above the overflow outlet invert to below the tank spill/top of the tank
Detention volumes are used as buffers to decrease output flow rates in situations of high input flow. If the tank has no detention storage, set the detention volume depth equal to the overflow outlet diameter.
Defines the diameter of the overflow orifice, located at the base of the detention storage.
Orifice discharge coefficient
Discharge coefficient used in the evaluation of the orifice flow equation.
External top up
Enable external top-up
If enabled, allows for the tank to be topped-up with mains water so that the tank always maintains a user-specified water level. When you enable external top-up, Urban Developer handles the mains connection internally.
Defines the rate of mains water top-up in litres per second.
Top-up triggered on
Defines the depth above the tank base at which the tank will start to top up. This depth must be greater than the height of the off-take.
Top-up triggered off
Defines the depth above the tank base at which the tank will stop automatically topping up. This depth must be greater than the Top-up triggered-on depth.
> Top-up triggered on
First Flush System
Enable first flush system
If enabled, changes the tank inflow behaviour so that a user-specified volume of water will bypass the tank before inflow to the tank occurs.
First Flush Volume
Specifies the volume of water the first-flush device diverts.
First Flush Outlet flow rate
Specifies the outflow rate to the selected discharge outlet.
Specifies the tank outlet that first-flush outflow is discharged through.
Detention outflow specifies that the first flush volume discharges via a connection to the detention outflow pipe.
Spill specifies that the first flush volume discharges via spilling from the tank.
The Tank node is configured via the node Feature Editor. Node properties are accessed through 4 levels:
1 Tank Dimensions
2 External top-up
3 First Flush behaviour
4 Overflow configuration
This material has been adapted from:
eWater Cooperative Research Centre (2011) Urban Developer Product Specification: Storage Tank Routing v0.4. eWater Cooperative Research Centre, Canberra. 23 June 2011.