City outlines Fippening Park stormwater swale project to reduce phosphorus runoff; DEQ grant paused pending federal guidance

City engineering consultants and parks staff presented details Feb. 24 on a stormwater infiltration project at Fippening Park intended to reduce phosphorus entering the lake.

Justin Shaw of HMH Engineering said the project uses the park’s sandy soils to infiltrate and treat stormwater before it reaches the lake. The design calls for an open swale with soft slopes, five dry wells to handle large storm events, and a CDS (vortex) manhole to capture sediment. Shaw said the deepest point of the swale will be roughly 7 feet and that side slopes range from about 4:1 to 6:1; the swale footprint extends roughly 75 feet across the site. A new paved east–west path will provide public access and allow maintenance crews to reach the swale internals.

"What we're gonna do is we're gonna put in a manhole here, catch the water that typically goes to the lake untreated, bring it into this swale system...let it slowly infiltrate…