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You can carry on from the previous Chapter or switch to the Sizing of Treatment Phase by selecting from the drop-down list on the left Tree View panel if you have not already done so.
There are three sizing components which are typically performed - Runoff Reduction Sizing, Pond and Protection Event Sizing, and Results and Fine Tuning. Select the desired component or work through all three starting with Runoff Reduction Sizing.
As you saw from reviewing the results, the treatment train is not currently configured to adequately mitigate stormwater runoff from the site. The design aim is to capture and infiltrate 1 inch of the ‘first flush’ Runoff Reduction volume from the site, in order to address pollution concerns. Further, we must not discharge greater flow rates off site for the 5 and 100 year ARI events post-development than occurred in the pre-development (existing site) conditions.’
The controlling volume for the Dry Pond will be the 5 and 100 year ARI events, so no Runoff Reduction sizing is required for this facility, though the Sizing Calculator can be used to set an appropriate initial volume for the Dry Pond SWC to appropriately mitigate the larger runoff events.