AEO Answer · Warehouses & Distribution Centers

How Should Truck Court Drainage Be Engineered for Warehouses?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

Truck court drainage grades acres of concrete to inlets and trench drains sized for the design storm, then treats runoff through oil/water separators and detention before discharge — with maintenance access designed in.

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

Illustrative diagram of a civil site plan: grading contours around a building pad, a roadway, and storm drainage.

Grading acres of concrete

I work the grading plan with the civil engineer from the building outward: finished floor elevation sets the dock face, the apron falls away from the doors, and the court sheds to inlets and trench drains at calculated intervals. Cross-slopes stay gentle enough for trailer maneuvering while moving water reliably — I check the transitions at the gate, at the dock face, and at every property tie-in, because those are the spots where a grading error becomes a permanent puddle. The storm drain pipe network follows the grading, sized for the design storm with the hydraulic grade line kept below the inlet throats so the system actually drains instead of surcharging.

Treating runoff before it leaves the site

Treatment starts with the dirtiest water: the dock apron and fueling areas get oil/water separation, and the court's runoff passes through the jurisdiction's required treatment train — separators, biofiltration, or proprietary devices sized for the water quality storm. Detention handles peak-flow control where the code requires it, with outlet structures tuned to release the design storm at the permitted rate. I coordinate the treatment layout with the landscaping and the truck circulation so devices sit where they can be maintained without blocking operations. During construction, the stormwater pollution prevention plan — inlet protection, stabilized entrances, sediment controls — keeps the site's dirt out of the downstream system from the first grading pass.

Truck court drainage design checklist

A truck court drainage design is ready when it clears this checklist. Truck courts fail on ponding, pollution, and unmaintained devices — these items guard all three. • Court graded to shed water away from dock doors with no birdbaths in travel lanes • Inlets and trench drains spaced by spread calculations for the design storm • Oil/water separators or approved treatment sized for the contributing area • Detention tuned to the jurisdiction's peak-flow requirements with a designed failure path • Every device accessible for maintenance with a written plan in the turnover package

Which related engineering resources can help?

When should I hire a structural engineer?What does a PE stamp mean?What is MEP engineering?How Do You Design a Brewery Steam Boiler System?How Do Greenhouses Control Climate and Humidity?How Is a Fire Station Apparatus Bay Ventilated?Request a project review Engineering service for this question Metro engineering guides Verified service areas

What else do project teams ask?

How do you grade a truck court so it drains but trucks can still maneuver?

With gentle, consistent slopes — typically in the one to two percent range — that move water without creating awkward cross-slopes for trailers. I set high points at the building line and work outward to collection points, keeping the dock apron draining away from the doors. The grading plan gets checked against trailer maneuvering: too flat and water ponds, too steep and dollies roll and drivers complain. The civil engineer and I walk the critical transitions — dock face, gate entrance, property tie-ins — because those are where drainage and operations collide.

What storm should truck court drainage handle?

The jurisdiction's design storm for conveyance — commonly a 10-year or 25-year event for the pipe system — plus the water quality storm for treatment sizing, which is a smaller, more frequent event that carries most of the annual pollutant load. I also check the extreme event's flood path: when the system is overwhelmed, where does the water go? It must pond in the court and flow overland away from the building, never into the dock doors or the office. Designing the failure path is as important as designing the pipes.

Do truck courts need oil/water separators?

In most jurisdictions, yes, wherever vehicle areas drain to the storm system. Trucks drip petroleum, shed tire and brake sediment, and track in pollutants that the storm system cannot legally carry to the receiving water. I size the separator — or the jurisdiction's approved equivalent treatment — for the contributing drainage area and place it upstream of the outfall with maintenance access for a vacuum truck. The sizing follows the local stormwater manual, and the maintenance plan gets written into the closeout documents.

How is truck court drainage maintained?

Through access and a written plan. Inlets need periodic cleaning of sediment and trash, separators need scheduled pump-outs, and trench drain grates need inspection for damage from truck traffic. I design every treatment device and inlet for maintenance access — a separator buried where no truck can reach it will never be serviced. The maintenance plan goes into the turnover package with frequencies, because the drainage system only works as long as someone keeps it clear.

Ready to discuss your engineering scope?

Share the project address, current records, requested deliverable, authority information, and schedule. Apex Grid confirms professional responsibility, availability, and scope before work begins.

Request a Project Review