Colleges green parking lot nearly complete

There are enormous parking areas at the Overland Park college, which accommodate the more than 20,000 part-time and full-time students enrolled this fall. Those areas generate a huge volume of dirty runoff during a storm. Much of that water ultimately flows into Indian Creek south of the campus.

Last year, the colleges trustees approved a project on the southeast area of the campus to slow the flow of the runoff and clean it at the same time.

It uses a system of bio-retention cells, bio-swales, and a submerged wetland in which depressions in the ground capture and detain the runoff. This enables the engineered soils and plant roots to absorb and filter the water before re-entering the concrete storm system and ultimately the creek.

By adding these different units throughout the parking lot were able to reduce sediment in the water by 90 percent and reduce some of the chemicals, including petro-hydrocarbons, by 80 percent, said Scott Bingham, a landscape architect at Bowman Bowman Novick Inc.

He said students this fall will be able to sample the quality of the water before it goes through the system and compare it with the quality at the end of the process. A small series of rock ledges will act as classroom seating for biology students at the end of the 24,300-square-foot south retention basin.

The college received a $867,000 federal stimulus grant to pay for the project as well as another $100,000 from a student-funded green fee.

Slowing the speed of the runoff is important for residential areas south of the college. For years the runoff from the four large parking lots on the campus sent a cascade of water into a large drainage system under the Kimberly Downs subdivision.

Homeowners said they watched as the water blew out a section of that drainage system on two occasions.

Bingham said the improvements to the parking lot should greatly reduce that problem.

Plants that will absorb some of the water include Indian seaoats grass, prairie dropseed, cardinal flowers, little blue-stem grass and blue flag iris.

At one of the bio-retention cells, a new product has been installed that slowly wicks water down to an underground piping system. A pervious concrete walkway will encircle the south basin and allow rain to soak through the concrete rather than become runoff.

Bingham said the retention basin, which will act as a submerged wetland area, is designed so that the water wont stagnate. For most of the year, this area will appear dry. During a rain event, it will fill up but wont remain full for long.