Deerfield Residence Landscape DesignTraditional Landscape, Chicago

When Drainage Should Go UndergroundSubdrainage is preferred when there is not enough ground to work with for shaping and grading a swale that can handle all of the stormwater runoff. Tight urban courtyards are an example of when a homeowner might opt for buried drainpipes to carry away roof runoff from a large home. Subdrainage is hidden, occurring in underground systems of concrete catch basins and PVC pipes. Subdrains have become less popular as swales have grown in popularity. Swales can be used in conjunction with drain inlets or buried drains when there is not a sufficient infiltration area. Drain inlets are also often used as backup drainage for rain gardens. The rain garden is designed to handle runoff from the majority of storms, but in the event of a major 100-year storm, the overflow water will have a place to go via a drain inlet that connects to the city system.The far corner of the yard in this photo has a drain inlet that connects to a larger pipe drainage system. Drain inlets can be used in small urban gardens that do not have space for swales or do not have adequate soil depth for infiltration. Sometimes there just is not enough space on the ground to handle the runoff. The slope of the site is also ultimately related to the size of the yard, because a swale requires more space to meander along with check dams and terracing on a steep site.