Stormwater and Drainage Construction in Houston

Detention is the biggest structure on many Houston sites, and on a dry day it holds nothing at all. That is the odd arithmetic of drainage work here: the pond, the storm trunk line and the outfall can cost more than the building shell, and their entire job is to be empty and ready for the storm that arrives twice a decade or once a century.

We build stormwater systems as part of ground-up commercial work, and as stand-alone retrofits when an owner needs to fix a site that floods, ponds or fails an inspection. The scope runs from inlets and leads through storm sewer, junction boxes, outfall structures, detention basins, underground detention vaults, and the erosion controls that protect all of it during construction.

The reason this scope deserves its own attention is that nothing else on the site can be finished until the water has somewhere to go. Paving cannot be graded without inlet elevations, foundations cannot be set without a known outfall, and a certificate of occupancy often waits on a drainage sign-off. If you are laying out a whole tract, our site development and utilities page covers how drainage fits with water, sewer and paving.

The rules that size the pond

The City of Houston's stormwater guidance to developers, dated November 2025, sets allowable outflow at 0.5 cubic feet per second per acre for a 2-year rain and 2 cubic feet per second per acre for a 100-year rain, bases detention on tract size rather than lot size, and describes a supplement to the Infrastructure Design Manual that removed the old detention curve and added a redevelopment credit. For an owner redeveloping an already paved site, that credit can change the size of the pond a great deal, so we ask the engineer early whether it applies, and we fold the answer into the review sequence described under permitting and entitlements.

In unincorporated Harris County the floodplain regulations take over, and they are stricter than most owners expect: fill to raise a structure is prohibited in the 100-year floodplain, any reduction in storage within the 500-year floodplain has to be offset one-to-one, and lowest habitable floors must sit 24 or more inches above the 500-year elevation or 12 inches above the crown of the nearest public street, whichever is higher. Those numbers push designs toward excavated storage rather than raised pads, and they shape the earthwork we price in mass grading.

A region drained by design, tested by weather

The Harris County Flood Control District's history timeline records that Hurricane Harvey dropped about 1 trillion gallons of water on the county over four days, touched all 22 watersheds and flooded more than 120,000 structures. Nobody who builds here treats a drainage report as paperwork after that. Lenders, insurers and tenants all ask what the site does in a hundred-year storm, and a contractor who cannot answer in specifics is a risk.

Even the engineered flood-control system has limits that owners should understand. Reporting on the Addicks and Barker reservoirs in west Houston noted that the Army Corps of Engineers had added seepage controls to the dams without making them higher or the reservoirs deeper, and that subdivisions near the Energy Corridor flooded when water was released during the storm. For anyone building in the Energy Corridor and nearby, the lesson is that regional infrastructure sets the floor, and a site still needs its own detention and finished-floor margin.

How we sequence the drainage package

Drainage goes in first and gets protected longest. We typically open the outfall end of the system before anything upstream, so water has a path during construction, and we install the detention basin early enough to serve as a sediment trap while the pad is built. That avoids the common failure of a site that silts its own storm lines before the first slab is poured, which matters most to public sector owners who inherit the maintenance for the life of the facility.

Pipe goes in with bedding and compaction checked at each joint, and structures are set to survey control rather than to the plans alone. Before we backfill, we invite the engineer or inspector to look at the line and grade, because uncovering a pipe later costs far more than waiting a morning. Outfalls get their riprap or energy dissipation as the final step, with the connection to the receiving ditch coordinated with the drainage district or municipality that owns it.

Basins, vaults and everything between

Open detention is the economical choice when land is available, as it usually is around a distribution center campus, with side slopes, a low-flow channel, a restrictor at the outlet and maintenance access that a mower or a small excavator can use. Where land is expensive, as in dense urban parcels, we build underground detention using large-diameter pipe or concrete vaults beneath the parking, which turns a pond into usable pavement and shifts the cost into structure and excavation.

Smaller scopes matter too. We install and repair inlets, trench drains, area drains at dock aprons, roof leader tie-ins and flumes, and we regrade swales that have drifted over the years. For a parking lot that holds water, the repair is often a combination of regrading, new inlets and edge restoration, and we diagnose it with a level and a hose before we propose a fix.

Trenches, tides and temporary controls

Deep storm lines and large structures put workers in excavations, and we treat trench protection as a standing requirement rather than an option. Shoring or trench boxes go in before anyone enters, a competent person inspects daily and after rain, and ladders and spoil setbacks are set as the work moves. Groundwater in the coastal plain often arrives sooner than the geotechnical report suggests, so dewatering is planned, not improvised.

Erosion and sediment control is the other compliance front. Silt fence, inlet protection, stabilized construction entrances and basin outlet controls are installed before ground is disturbed and maintained through the storms of the build. A failed control can mean a notice, and a silted receiving channel is the sort of problem a neighbor or a district will remember.

Start with the drainage plan

Send us the civil drawings or the flooding complaint and we will walk the site, price the system and tell you where the schedule risk sits.

Common Questions

Does the pond have to be built before the building?

In most cases it should be at least excavated and stabilized first, because it handles construction runoff and proves the outfall. Final finishing of the basin, such as the restrictor and landscaping, can follow the building. We agree the sequence with the engineer so the pond works as a sediment trap during the build.

What does underground detention cost compared with a pond?

The structure itself costs more than an open basin, but the land it frees often more than makes up the difference on a tight urban parcel. The comparison depends on land value, soil conditions and maintenance expectations. We price both options when the civil engineer is still weighing them.

Can you fix a parking lot that floods after every heavy rain?

Usually, but the cause has to be found first. It might be a blocked lead, an inlet set too high, a lot that has settled, or an undersized system. We survey the site, trace the lines and then propose a repair, which can be as small as new inlets or as large as regrading and repaving.

Who inspects storm sewer before backfill?

The engineer of record, the city or county inspector, or both, depending on the jurisdiction and who will own the line. We schedule the inspection ahead of the work so the trench is not left open longer than necessary.

How do the Harris County floodplain rules affect our design?

They affect finished-floor elevation, fill and storage. A site in the regulatory floodplain cannot use fill to raise the building in the 100-year zone, so storage is typically excavated and the building is designed at the required margin. A project in the City of Houston has its own elevation standard, which your engineer will apply.

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