Water can have a detrimental effect on pavement performance, by either weakening subgrade materials, erosion of surface material, or by freeze thaw damage. Rainwater runoff and groundwater are common sources of water damage which can be prevented by ensuring proper surface and subsurface drainage.
Surface drainage is the ability of your parking lot to allow water to freely flow over the surface and off the pavement. Good surface drainage will be puddle free and will not have areas where water can enter the asphalt pavement. Ways to provide proper surface drainage are:
- Parking Lot Slope – The slope plays a significant role in the effectiveness of your parking lot drainage system. The pavement should be sloped to allow rainwater to flow quickly over the surface and off the pavement to the intended areas.
- Curb & Gutter – Installing concrete curb and gutter will help direct the flow of water on your parking lot and into a catch basin or grass area.
- Catch Basin/Drain – Catch basins are planned and built into the framework of a parking lot to allow water a place to drain off the pavement. Regular maintenance and cleaning are required to keep your catch basins functioning properly.
Subsurface drainage is the ability of groundwater to be removed from the underlying sub soils. This water is typically trapped in the soils beneath your parking lot. The trapped water creates soft areas in the subgrade, reducing the strength of the pavement and making it susceptible to frost movement. Drain tile can be used to provide a way for the groundwater to drain out of the soils. The dry soils will then support the traffic loads and will reduce frost heave potential.