Friday, January 21, 2011

Harvard Stormwater Management Improvement Project

Stormwater management design addresses water quantity and quality.  The purpose of this improvement project was to address failing pavement and poor stormwater management.  Public Works chose to integrate raingardens with the major storm drainage system (inlets and underground pipe).  The raingardens reduce the amount of impervious surface creating stormwater runoff and provide an opportunity to remove pollutants from the “first flush” of stormwater runoff.

Photo:  The existing pavement failed and is not used as a driving surface by residents.  Most of the failed pavement was removed and not replaced, reducing impervious area.

Photo:  Harvard prior to construction of the stormwater management system.

Photo:  Harvard raingardens under construction prior to raingarden soils, mulch and plants.  Cleanout for underdrain pipe is exposed. 

Photo:  Harvard raingardens during rain event. Notice that the water is spreading out in the raingarden, slowing it down, allowing it to infiltrate into the underlying soil layer.  Next step is to plant vegetation to provide more water quality benefits.

 Photo:  Harvard raingardens immediately after planting.  Native plants were used.  It takes two to three years for native plants to become fully established.  Many of these plants bloomed the first year.

The function of the raingarden is to slow down the runoff from smaller rain events and allow it to infiltrate into the underlying soils.  Slowing runoff allows sediment to drop out from the runoff.  The plants and soils of the raingarden remove some pollutants found in stormwater runoff.  The final product is cleaner water in our creeks and streams.