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, 7 years ago
<p>Over soils with slow infiltration rates, it is advantageous to drain a portion of the stored water prior to any upcoming storm. This popular design choice can optimize annual water balance, mitigate peak flow rates and by ensuring water flow through, can reduce the accumulation of sodium and chlorine ions from winter salting. </p>
===Materials===
<h4>Gravel storage layer</h4>
{{:Gravel#Underdrains}}
<h4>Underdrain pipe</h4>
{{:Pipes}}
<h4>Geotextile</h4>