The Dispersal of Collected Drainage and Maintenance of the Home and Site Drainage Systems
Once a site and building drainage system is in place, its maintenance becomes most important to protect the building and the site. The amount of runoff now collected and its dispersal is significant. Various methods can be used to redirect the captured runoff from the building and the site.
If the drainage system’s trenches and outflow elevations are above the elevation of the street gutter, then the collected runoff can be drained through a weephole in the curb. If the system drains runoff at a lower elevation than the existing street storm gutter, the runoff can be captured in a sump and the runoff pumped up to the street gutter. In this approach it is important to have a backup battery-powered pump in the event that the heavy rainfall is associated with a power outage.
As an alternative to a sump-and-pump system to discharge the collected runoff, an alternative is a well-designed dissipater. In this case, runoff is collected and then allowed to seep out of the point of collection into deeper areas that contain clean crushed rock backfill. This system can also serve to provide natural irrigation of planted areas.
Regular maintenance of the home and site drainage system is essential to maintain its effectiveness year after year. Ensure that positive slope of associated site soils is maintained, and that all collection and outflow points are intact. All runoff should have a cleared flow route away from the building. Where runoff is drained into closed pipes, it is important to incorporate clean-outs to enable the removal of sediment as necessary. Existing roof gutters should also have screen/filters that cover the opening of the roof gutter–which assist in preventing sediment clogging of the gutters and downspouts.
Water should not be permitted to pond or flow adjacent to a building’s foundation or on slopes, as these characteristics are often related to building subsidence and potential slides. Don’t connect roof water drains to subsurface collection systems as this can overload a subterranean collection system. Correct any damage to the drainage system as soon as possible; prompt attention to minor problems may prevent them from growing into major problems. Make sure all system elements are in good repair.
Regarding the general site, it is important not to over-irrigate landscaped areas. Sprinklers or water hoses should not be left on longer than necessary and never overnight. It is best to landscape with native plants that thrive in dry conditions.
In the next issue, I will begin to review the effects that earthquakes can have on residential buildings and the engineered strategies to reinforce them.
