Exam 3 question

Not sure if I’m getting this, what’s the difference between area drain planted median and a bioswale in a parking lot? They seem to be very similar.

The owner of a suburban commercial building is reviewing methods of directing stormwater runoff to the municipal sewer system. The local zoning ordinance requires the project to accommodate parking for 195 cars. The owner wishes to reduce costs as much as possible, but is also commited to providing a certain amount of vegetation in the parking lot for aesthetic purposes.

Which of the following methods of stormwater management will provide visible vegetation while also managing stormwater flow to the municipal sewer?

Detention tanks

Incorrect. A detention tank is typically located below grade to collect stormwater runoff from a building roof. This would not satisfy the owner’s requirement to provide a cost-effective means of draining the parking lot, nor their desire to have visible vegetation.

Area drains in planted medians

Incorrect. Area drains in planted medians may be required in large quantities given the size of the parking lot. This method is likely not as cost-effective as providing bioswales.


Correct. Bioswales provide vegetated ditches which collect and direct stormwater to a site’s sewer outlet. In this scenario, bioswales can both accommodate the owner’s desire to provide visible vegetation while also effectively managing parking lot drainage.

Reference: Site Planning and Design Handbook