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C-5

6. HOW IS A RAIN GARDEN SIZED TO MEET MINIMUM REQUIREMENT #5?

Rain Gardens must have a minimum horizontal projected surface area below the overflow (Top Surface of Ponding, shown on page 24 of this
Handbook) which is at least 5 percent of the area draining to it. The designer may choose a larger size, but Rain Garden performance does not need
to be predicted with computer models to meet Minimum Requirement #5.

2012 SWMMWW Reference:
• Volume V, Section 5.3 Best Management Practices for On-Site Stormwater Management, BMP T5.14A: Rain Gardens, pages 5-11 through 5-12.