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Surface Drainage

Common Drainage Infrastructure

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INLETS

Area inlets are installed within landscaped areas to drain water trapped at low points.

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LAWN EDGING

Perforated lawn edging, which allows water to seep through it, is a good solution when a transition between landscaping types is required.

FRENCH DRAIN

French drains are below-ground drains constructed of perforated pipe in a rock or gravel trench.  French drains are installed to drain flat swales, flat landscaped areas,  or along edges of sidewalks.  French drains discharge either into a storm sewer or ground surface.

Diagram of a French drain cross-section.

FRENCH DRAIN ALONG SIDEWALKS

French drain along a sidewalk in subdivision.

FRENCH DRAIN IN YARDS

French drain in yard.

TYPES OF SWALES

Swales, typically found in drainage easements, around retaining walls, roadways, sidewalks, and between buildings, provide an effective way to manage surface water.  Swales can be deep or very subtle formations on the ground surface.


Note:  Covering swales covered in wood chips, rocks, rocks or cobbles can be counterproductive because these items function as barriers to flow, slow water down, and allow water to infiltrate into the soil, instead of moving it quickly across the surface.  Grass and native surfaces are the best for swales.

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RIPRAP SWALE

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COBBLE/ROCK SWALE

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CONCRETE SWALE

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GRASS SWALE

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NATURAL SWALE

SWALE SHAPES

Swales are "V"-shaped or flat-bottom-shaped features in the ground surface that divert drainage.

Diagram of a V-shaped swale cross-section.

V-SHAPED SWALE

Diagram of a flat bottom swale cross-section.

FLAT BOTTOM SWALE

ROADWAYS

Roadways are important drainage infrastructure in a residential development.

Asphalt roadway with curb and gutter and detached sidewalk in a subdivision.

ROADS WITH CURB AND GUTTER

Curbs and gutters route drainage in the street and direct flow to inlets and other storm sewer infrastructure.

Drainage ditch along a rural two-lane asphalt road.

ROADS WITH DITCHES

Streets without curbs and gutters have ditches on each side to collect water from the adjacent land area and route water to downstream drainage facilities.

SIDEWALK CHASE

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Sidewalk chases are used to route drainage from one side of the sidewalk to the other without flowing over the concrete surface.  Sidewalk chases are the solution to water pooling at the edges of sidewalks and nuisance drainage flowing over the concrete surface.  Nuisance issues water on the surfaces of sidewalks can cause slick algae growths and ice build-up.

Sidewalk chase that has installed to fix drainage problem.
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