Bioretention cells are typically designed by professionals and use a soil media that must drain below the mulch line within 18 hours.
Examples of biotretention on the Stormwater Solutions Self-Guided Tour:
Chamberlain Place Apartments
6220 Chamberlain Place
(At corner of Chamberlain Place and Catherines Way)
Rural Hall Elementary School
275 Hall St.
(At corner of College and Washington streets)