Practice 02 / 05
Slow it, cool it, filter it.
Storm water management at terminal scale. Large impervious surfaces next to rivers and coastlines demand approaches that slow, cool, and filter runoff before it reaches the water that matters.
The Short Version
Terminals are not parking lots. The water math is different.
A typical parking lot is engineered so water never accumulates. An industrial terminal might be designed to store several inches of water for a short duration during a critical storm event. That difference drives everything on this page.
Runoff traveling over paved terminal areas picks up debris, chemicals, sediment, and pollutants, and carries them toward the nearest watercourse. Best Management Practices (BMPs) are the primary tools for managing that discharge: reduce the pollutants in runoff, decrease the volume of discharged storm water, and protect the receiving stream, river, or harbor.
The strategies below overlap deliberately. Storm water management and spill containment can share infrastructure. Porous pavement replaces entire pipe networks. Floating berths protect the shallow-water habitat that fixed wharves destroy.
12–36″
Infiltration bed depth for porous pavement systems
2–3×/yr
Vacuum cleaning that replaces resealing entirely
1-in-100
Storm events designed for with overflow control
20+ yrs
Service life of Columbia River floating berths
Inside This Practice
Five working approaches.
01 · Structural Systems
Catch basins, separators, and the hardware of clean runoff
Manufactured structures capture storm water and treat it in stages. Catch basins let sediment settle before discharge; geotextile inserts trap sediment and absorb oil at the inlet. Oil-water separators handle trucking areas where spills are inevitable, and hydrodynamic separators swirl sediment out before release.
The common thread: none of it works without scheduled maintenance. A catch basin that never gets cleaned stops being treatment and becomes storage.
02 · Natural Systems
Ponds, bioswales, and buffers that double as open space
Retention ponds hold water indefinitely and recharge groundwater. Detention ponds catch the surge from a critical storm and release it at a controlled rate. Bioswales slow and cool runoff where porous paving cannot go, and riparian buffer zones of native grasses and trees stabilize the bank while shading the water.
Where space allows, natural features do treatment work and aesthetic work at the same time.
03 · Shallow Water Habitats
The ecosystem next to the berth
Shallow water habitats keep sediment in place, recycle nutrients, and provide migratory paths for fish. They are also directly in the shadow of terminal infrastructure. Design choices matter: floating berths in deeper water instead of fixed wharves with bulkheads, current paths left intact, shade minimized.
Operations matter too. Treated runoff, spill action plans, noise discipline during spawning seasons, and vessel speed limits all protect the habitat after opening day.
04 · Porous Pavement
The pavement that is the drainage system
Porous asphalt lets storm water infiltrate straight through the surface into a stone bed below, eliminating most of the piping and catch basins a conventional lot requires. Runoff temperature, velocity, volume, and pollutant load all drop. Unit cost runs 10 to 20 percent above standard asphalt, but the total-system comparison, with storm water fees and infrastructure included, is often a win.
It performs well in winter, resists black ice, and installations dating back decades are still functional. The tradeoff is discipline: vacuum it, never seal-coat it, and keep heavy spill-prone loading zones on conventional pavement.
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04 · Porous Pavement
The spec, the upkeep, and where it does not belong
What sits under the surface
An infiltration bed of clean, uniformly graded AASHTO No. 3 aggregate, 12 to 36 inches deep with roughly 40 percent void space, wrapped in non-woven geotextile. A choker course of AASHTO No. 57 aggregate levels the bed for paving, and continuously perforated HDPE pipe distributes runoff across the bed bottom and provides positive overflow.
Feasibility starts with the subgrade
Sand infiltrates well; dense clay may rule the system out. Where soils drain poorly, the bed can be designed for slow discharge instead. Systems are typically sized for two- to ten-year storms with the one-in-a-century event studied in design, and an overflow control keeps water from ever rising to pavement level.
Maintenance is one job
Keep fines out of the voids. Vacuum two to three times a year, clean inlet structures annually, never seal-coat, and never pressure-wash. Plow with the blade set slightly high. Salt works; sand and cinders are prohibited because they clog the voids.
Where it does not belong
Truck loading zones with heavy axle loads and frequent spills stay on conventional pavement, with runoff routed through oil-water separators to an adjacent bioswale.
05 · Floating Berths
Berths that rise with the river
Floating platform docks for Ro-Ro and Pure Car Carrier discharge are working today on the Columbia River at the Ports of Portland and Vancouver. Trestles and hinged ramps connect shore to platform, preserving the shallow-water habitat a fixed bulkhead would bury. The platform rides tidal and seasonal water levels, keeping dock and vessel at a constant relative elevation.
Two of the existing berths were fashioned from World War II Liberty Ships and have served for over two decades. Permitting and capital costs routinely come in below pile-driven alternatives.
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05 · Floating Berths
How the Columbia River platforms work
What is floating
Floating platform docks for Ro-Ro and Pure Car Carrier discharge are in daily service at the Ports of Portland and Vancouver. Trestles and hinged ramps connect the shore to the platform, and the platform rides tidal and seasonal water levels so dock and vessel stay at a constant relative elevation.
Why it protects habitat
A fixed wharf with bulkheads buries the shallow-water zone that keeps sediment in place, recycles nutrients, and gives fish a migratory path. A floating berth sits in deeper water and leaves the current paths intact.
Service record and cost
Two of the existing berths were fashioned from World War II Liberty Ships and have served for more than two decades. Permitting and capital costs routinely come in below pile-driven alternatives.
Proven In The Field
Where this practice has shipped.
Water Systems
T6 Porous Pavement
Port of Portland. Multi-decade porous-asphalt installation with the spec, maintenance program, and cold-weather record.
Read the case study →
Water Systems
T4 Storm Water Features
Port of Portland. Structural treatment combined with bioswales and riparian-buffer integration on a working terminal.
Read the case study →
All Pillars
Explore the other practices
Air Quality, Energy Efficiency, Terminal Design, and Innovation & Resilience. Each pillar collects the technologies that shape a terminal’s footprint.
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