How it Works
When it rains, stormwater enters the storm sewer system through the inlets on your street. The water flows through a series of pipes to the large diameter “trunk” storm sewers located under Lake Avenue, Hunter Road, Wilmette Avenue, Hibbard Road and Laramie Avenue.
During light to moderate rain events, there is enough pipe capacity to move the water efficiently through the system. During heavy rain events, however (events greater than a 10-year storm), the storm pipes will fill to capacity.
When the water in the pipes reaches a critical elevation, the stormwater will flow by gravity into the three vaults under Community Playfield, Hibbard Road and Thornwood Park. The stormwater will continue to be stored in the vaults until the receiving sewers have enough capacity to accept the stored flow.
The Community Playfield vault holds 6.5 million gallons, is 6-7 feet deep and drains by gravity. The Hibbard Park vault is 15-feet deep, holds 3.6 million gallons and drains by both gravity and pumps. The Thornwood Park vault is 15- feet deep, holds 4.5 million gallons and drains by gravity and pumps.
All of the stormwater west of Ridge Road drains to a single pumping station on Lake Avenue, where it is pumped to the North Branch of the Chicago River.