Dosing To Discharge

The Dosing to Discharge page captures the physical relationship between the dosing tank and the discharge absorption area. The elevation change and distance you enter here determine whether the system can use a pump or a siphon, and drive the hydraulic calculations for the rest of the design.

Fields

Elevation Change (Tank to Bed)

The vertical distance between the ground level at the dosing tank and the ground level of the absorption area. Use the up/down radio buttons to indicate the direction:

• Up — the absorption area is above the dosing tank (pump must push effluent uphill)
• Down — the absorption area is below the dosing tank (siphon may be feasible)

Enter the absolute value in feet.

There is a “no-man’s zone” for elevations where the bed is downhill from the tank. A tank with a pump needs to have its high water level below the bed’s laterals. A siphon system needs to have sufficient elevation to produce adequate head throughout its run. In practical terms that usually means the elevation drop cannot be less than 15 ft for siphons and not more than 4 ft for pumps. For longer delivery distances the tolerable elevation drops are even less forgiving.

Distance (Tank to Bed)

The horizontal distance from the dosing tank to the absorption area, measured along the delivery line path. Some allowance is made in the software to accommodate field irregularities. Enter the value in feet.

Extra Depth of Tank

Additional burial depth of the dosing tank below the normal grade line. This increases the effective head required for delivery. Enter the value in feet.

Pump vs. Siphon Feasibility

The wizard automatically selects between pump and siphon based on elevations and head requirements.

If neither pump nor siphon is feasible with your entered values, the wizard will display an error message explaining the shortfall (e.g., “Not enough drop for siphon by X ft and too much for pump by Y ft”). Adjust the elevation, distance, or extra depth to resolve.

Eljen GSF Systems

For Eljen GSF discharge - only pump delivery is available due to their timed dose requirement.

Tips

• Measure distance along the actual pipe route, not as a straight line.
• If you are unsure about the elevation change, use a conservative (larger for pumps, smaller for siphons) estimate. The wizard will select pumps with adequate margin.
• The extra depth field is useful when the dosing tank must be buried deeper to connect to an existing sewer line, to match the primary tank outlet elevation, or when the tank is uphill from the bed.
• If the bed is elevationally below the tanks and there is not enough drop for a siphon, consider moving the dosing tank farther down the hill and closer to the the bed.