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Where the curb cut width is constrained and a greater flow into the BMP is desired, the effective cross slope may be increased by adding a depressed apron.
{{Plainlist|1=Where:
{{Plainlist|1=Where:
−*''W<sub>T</sub>'' is the width of the inlet for complete capture (m),
+*''W<sub>T</sub>'' is the total width of inlet for complete capture (m),
*''Q'' is the design flow perpendicular to the inlet (m<sup>3</sup>/s)
*''Q'' is the design flow perpendicular to the inlet (m<sup>3</sup>/s)
*''S<sub>0</sub>'' is the longitudinal slope ratio
*''S<sub>0</sub>'' is the longitudinal slope ratio
*''n'' is Manning's 'n' (between 0.012 and 0.016 for concrete, depending on surface treatment), and
*''n'' is Manning's 'n' (between 0.012 and 0.016 for concrete, depending on surface treatment), and
*''S<sub>x</sub>'' is the cross slope ratio (typically between 0.015 and 0.04)}}
*''S<sub>x</sub>'' is the cross slope ratio (typically between 0.015 and 0.04)}}
+
+The value obtained for total inlet width can then be divided by a chosen number of inlets to determine the required width of each curb cut inlet. Curb cut inlets draining roadways should be a minimum of 0.45 m in width and are typically no wider than 2 m.
+
+Where the curb cut width is constrained and a greater flow into the BMP is desired, the effective cross slope (''S<sub>x</sub>'') may be increased by adding a depressed concrete apron.
Where the intention is to capture only a proportion of the flow, the ratio of flow entering the curb inlet may be calculated:
Where the intention is to capture only a proportion of the flow, the ratio of flow entering the curb inlet may be calculated:
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*''R<sub>c</sub>'' is the proportion of flow entering the curb cut, and
*''R<sub>c</sub>'' is the proportion of flow entering the curb cut, and
*''W'' is the available curb cut width (m)}}
*''W'' is the available curb cut width (m)}}
−==Example==
==Example==