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Five percent of the average annual demand can be estimated:
Five percent of the average annual demand can be estimated:
<math>D_{0.05} = P_{d} \times #\times 18.25</math>
<math>D_{0.05} = P_{d} \times n\times 18.25</math>
{{plainlist|Where:
{{plainlist|Where:
*''D<sub>0.05</sub>'' is five percent of the average annual demand (L)
*''D<sub>0.05</sub>'' is five percent of the average annual demand (L)
*''P<sub>d</sub>'' is the daily demand per person (L)
*''P<sub>d</sub>'' is the daily demand per person (L)
*''#'' is the number of occupants}}
*''n'' is the number of occupants}}


Then the following calculations are based upon two criteria:
Then the following calculations are based upon two criteria:
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When \(Y_{0.05}/D_{0.05}<0.33\), the storage volume required can be estimated:
When \(Y_{0.05}/D_{0.05}<0.33\), the storage volume required can be estimated:
<math>V_{S} = A \times C_{vol,E}\times R_{d} \times e</math>
<math>V_{S} = A_{c} \times C_{vol,E}\times R_{d} \times e</math>
{{plainlist|Where:
{{plainlist|Where:
*''V<sub>S</sub>'' &#61; Storage volume required (L)
*''V<sub>S</sub>'' is the volume of storage required (L)
*''A'' &#61; The catchment area (m<sup>2</sup>)
*''A<sub>c</sub>'' is the catchment area (m<sup>2</sup>)
*''C<sub>vol,E</sub>'' &#61; The design storm runoff coefficient for the catchment
*''C<sub>vol,E</sub>'' is the design storm runoff coefficient for the catchment
*''R<sub>d</sub>'' &#61; The design storm rainfall depth (mm), and
*''R<sub>d</sub>'' is the design storm rainfall depth (mm), and
*''e'' &#61; The efficiency of the pre-storage filter.}}
*''e'' is the efficiency of the pre-storage filter.}}


*Careful catchment selection means that the runoff coefficient, for a rainstorm event (''C<sub>vol, E</sub>'') should be 0.9 or greater.
*Careful catchment selection means that the runoff coefficient, for an individual rainstorm event (''C<sub>vol, E</sub>'') should be 0.9 or greater.
          
          
Finally, when \(0.33<Y_{0.05}/D_{0.05}<0.7\), the total storage required can be estimated by adding ''Y<sub>0.05</sub>'':
Finally, when \(0.33<Y_{0.05}/D_{0.05}<0.7\), the total storage required can be estimated by adding ''Y<sub>0.05</sub>'':

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