Structural stormwater infrastructure is the hard system: pipes, inlets, culverts, ponds, weirs, pumps, outfalls, and the concrete or riprap that keeps them from unraveling. It is designed to collect runoff, move it, store it, and let it out at a rate the downstream receiving waterway (typically ditch, stream or bayou) can take.
It is not the opposite of green infrastructure. Most Gulf Coast sites need both. A bioswale that dumps into nowhere is a mudhole. A pipe that dumps into an undersized bayou is a lawsuit.
What “structural stormwater” actually includes
- Conveyance. Inlets, storm drain, culverts, lined channels, outfall pipes.
- Storage and control. Detention and retention ponds, weirs, orifices, pumps where the site is below the receiving water.
- Stabilization. Riprap, headwalls, energy dissipators — the pieces that keep the outfall from eating the bank.
- Treatment that is still a structure. Oil-grit separators, vaults, constructed basins with a permanent pool.
NPDES construction permits and the SWPPP cover the site while it is bare. Post-construction rules cover what you leave in the ground. Hydraulics is the sizing. You need all three. See What is stormwater management?.
Structural vs green
Green infrastructure uses soil, plants, and permeable surface to slow and treat water before (or instead of) a pipe. Structural infrastructure is the pipe and the pond. A stormwater park can be both — East Pier is that mix on a real Cypress job, not a brochure.
Pick the system the soils, the tide, and the maintenance budget will actually support. Sandy coastal fill will infiltrate. A tidally backed canal will not. We do not specify permeable pavement over a clay pan and call it green.
What it has to do in our region
- Not flood the neighbor. That is a scenario-specific question H&H modeling answers.
- Not blow out the outfall on a 2-year storm and a 25-year surge in the same week.
- Meet the municipal or DOT standard that actually applies (city, county, MDOT, ALDOT, FDOT) — not a generic “best practice” paragraph.
- Stay maintainable. A pond nobody maintains or a pump nobody funds is not infrastructure.
How we use it
We grade the site, size the pipes and ponds, and put green features where they will work. The drawings have to be something a contractor can build and a reviewer can check. Civil design is most of our work; this is a large piece of it.
Cypress Environment & Infrastructure works from Biloxi, Mobile, and Pensacola, throughout the Southeastern US. Office hours are Monday–Friday, 9 a.m.–5 p.m.