Ida, an ‘800-year storm’

Posted by Rich Schwartzman on March 20, 2024

Brandywine Conservancy’s Director Of Community Services Grant DeCosta addresses Chadds Ford Township residents during a presentation of the flood study project spawned by the effects of Hurricane Ida.

The Brandywine Conservancy and its partners are taking their flood study meetings on the road. The first stop was in Chadds Ford Township this week.

Grant DeCosta, the conservancy’s director of community services, conducted the session as he did a larger meeting at the conservancy last month. This week’s meeting focused on reminding Chadds Ford residents what the conservancy and its partners are doing to help prevent the disastrous flooding that took place on Sept. 1, 2021, when Hurricane Ida hit.

Teaming up with the conservancy are Chester County Water Resources Authority, and the University of Delaware Water Resources Center, among others. Those three entities have taken the lead in the study project.

According to DeCosta, “Hurricane Ida was predicted to be a little over 14 feet. Our prior record was 17 feet but, what came into our area during Ida was 21 feet.”

He said that was unprecedented and “nothing we could have prepared for.”

The conservancy had 10 buildings impacted. Homes in the area were damaged or destroyed, as was Hank’s Place at Route 1 and Creek Road. Water volume from the storm was virtually “off the chart,” he said.

Water volume is measured in cubic feet per second, and DeCosta explained that a cubic foot is roughly the size of a basketball. Analysis from upstream and downstream indicates the volume from Ida was somewhere between 42,000 and 76,000 cubic feet per second, “which makes that an 800-year storm,” he said.

Goals of the study include understanding where and why the flooding happens to determine how best to protect properties in and around the floodplain, and to develop models for mitigating damage.

Potential solutions include looking at structural issues, retrofitting and making enhancements to current structures, and right-sizing existing infrastructure. Other potential solutions include looking at ways to increase flood storage capacity, restoring and preserving the current flood plain, and making policy and regulatory changes.

DeCosta said the study should be in draft form this spring and published this summer.

About Rich Schwartzman

Rich Schwartzman has been reporting on events in the greater Chadds Ford area since September 2001 when he became the founding editor of The Chadds Ford Post. In April 2009 he became managing editor of ChaddsFordLive. He is also an award-winning photographer.