Storm Water Quantity and Quality

When in rains, what happens to the rainwater? The development of the modern city often results in neglecting the effects of storm water on our environment. With ever increasing construction of impermeable surfaces such as roads, buildings and parking lots, we limit the areas where storm water can penetrate the earth’s surface to be recycled back into the ground. This reduced amount of infiltrating water can lower ground water levels, which in turn can stress on downstream environments, which depend on steadier flows of water. Storm drains help control the volume of water left on the surface but seldom separate potentially harmful pollutants that rainwater may have picked up off roadways and other infrastructure.


Did you know that approximately 70% of all storm drains lead directly to open waterways, without treatment; and that 46% of all impaired rivers and lakes in the U.S. are polluted due to uncontrolled storm water runoff?


As part of the LEED initiative, this property is taking action in protecting the quality of U.S. waterways by reducing the discharge of sediment, oil and chemicals into storm drains, surface water and groundwater. Infiltration basins are one way of offsetting these environmental impacts.


An infiltration basin is a facility constructed within highly permeable soils that provides temporary storage of storm water runoff. An infiltration basin does not normally have a structural outlet to discharge runoff. Instead, outflow from an infiltration basin is percolated through the surrounding soil. Infiltration basins are used to remove pollutants and to infiltrate storm water back into the ground. Such infiltration also helps to reduce increases in both the peak rate and total volume of runoff caused by land development. Pollutant removal is achieved through filtration of the runoff through the soil as well as biological and chemical activity within the soil. In order to ensure proper percolation in the 5 infiltration basins stationed on this property, both K4 and K5 sands (see sample materials below) are laid in the beds of these basins. These materials are highly permeable and can intercept silt, sediment, and debris that could otherwise clog the top layer of the soil below the basin. The sand layer will also facilitate silt, sediment, and debris removal from the basin and can be readily restored following removal operations.

Main storm water infiltration basin
Roof drains converge and are fed into one of the storm basins
Main basin storm drain inlet
Plastic barrier to prevent washout
Topped with K4 said for increased permeability. Shown with silt fence during construction
rip-rap: slows down incoming water to prevent basin erosion
Digging out the properties main infiltration basin
Highly permeable k5 sand to aid in rain water percolation