Arapahoe County planning commission reviews floodplain rules, mapping and development limits

Arapahoe County engineering staff on Sept. 2 briefed the Arapahoe County Planning Commission on the county's floodplain management program, including how FEMA flood maps are used in land‑development reviews and what types of development are allowed inside the 100‑year floodplain.

At the meeting, Sila Rethamel, Engineering Services Division manager, told commissioners that "we review and approve flood plain activities and we also permit and inspect those," and that the county's program is intended "to protect our residents from flood events and make sure that they have clean storm water runoff." Rethamel outlined the federal and regional programs that shape local rules, such as the National Flood Insurance Program and the county's participation in FEMA mapping and mitigation efforts.

Rethamel reviewed key technical concepts the county applies in reviews: the 100‑year floodplain (an area with a 1% annual chance of flooding), the floodway and the flood fringe. She said the county's standard for most projects is the 100‑year event and noted…