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Surge Tank Capacity: Calculations Are Deemed Reliable For Estimation Purposes Only

The document discusses sizing a surge tank for a septic system. It notes that a surge tank is often appropriate when peak flow is more than double average flow. It provides instructions for inputting estimated daily flows over a peak week and calculating the required surge tank capacity based on the design flow and highest cumulative daily flow plus a 20% safety factor. The goal is to size downstream system components to the design flow and size the drainfield to account for time dosed flow.

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Krishna Yeole
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244 views2 pages

Surge Tank Capacity: Calculations Are Deemed Reliable For Estimation Purposes Only

The document discusses sizing a surge tank for a septic system. It notes that a surge tank is often appropriate when peak flow is more than double average flow. It provides instructions for inputting estimated daily flows over a peak week and calculating the required surge tank capacity based on the design flow and highest cumulative daily flow plus a 20% safety factor. The goal is to size downstream system components to the design flow and size the drainfield to account for time dosed flow.

Uploaded by

Krishna Yeole
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLS, PDF, TXT or read online on Scribd
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Surge Tank Capacity

www.SepticResource.com (vers 15.2)

Property Owner: Date:

Site Address: PID:

Comments:

instructions: = req'd input = adjust if desired = self-calculated (DO NOT ADJUST)

Note: designing a flow equalization system using a surge tank is often appropriate when the peak flow is
more than two times average flow. Otherwise it may be simpler & wiser to design a standard system on peak flow.

1) Input the estimated daily flows of a peak/full capacity week. Start with the highest flow day(s) first.

Time dosed amount to daily +/- to Surge tank


gpd system downstream surge tank cumulative total
day 1 0 0 0 0
day 2 0 0 0 0
day 3 0 0 0 0
day 4 0 0 0 0
day 5 0 0 0 0
day 6 0 0 0 0
day 7 0 0 0 0 ***

0 gpd Daily average flow

2) Enter your desired "design" flow (must be equal to or larger than the Daily average flow)

0 gpd Design flow (components downstream of the surge tank must be capable of this flow)

Assuming the surge tank is first in line, the downstream septic & lift tanks would then be sized on this flow.
However, the drainfield would be sized on this flow --> 0 gpd.
This is because MN7080 drainfield sizing assumes that Average flow = 66% of Design flow.
With "flow equalization" or "time dosed" systems, the avg flow often equals 100% of design flow.
Therefore, the dispersal area must be sized at 1.5 times the design flow (time dosed flow).

3) Enter day 7's "surge tank cumulative total" (box marked with ***)
(if you listed the highest flow days first, this value should be roughly = 0. If not, enter the value now)
0

4) Results:

design maximum daily


surge capacity req'd = flow + cumulative amount plus 20% (to cover pump & safety factor)
0 = 0 + 0 + 20%

Calculations are deemed reliable for estimation purposes only.


Designer Signature Company License# Date

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