The Columbia Public Works Department had a problem. There were too many employees for its small parking lot. Workers would park along the street, disturbing residents living close to the department. At the end of the parking lot was an underground cavity, which was used to drain water into local creeks and rivers in the 1980s and has not been used since. But it was a good place to add onto the current lot, however there was a worry about drainage.
The department made plans to expand the parking lot, but rather than use traditional pavement, the group saw a way to experiment, while also solving all of its problems. The PaveDrain Company is the inventor of a new porous pavement that drains water through each brick laid down. The bricks fit together like puzzle pieces and are woven together by a strong wire in pallets. In between each brick is a slight crack that allows the rain water to go underground. The water then trickles through a layer of gravel, which lies just underneath the pavement. Under the gravel are Atlantis Storage Triple Tanks which are covered in fabric. These tanks filter the sediment out of the water. It then flows through a pipe and out to creeks and rivers.
Mike Heimos is the storm water educator for the city of Columbia. He compared the PaveDrain system to a Brita Water Filter. “All the water comes down and filtrates down and will slowly leave and filter into Bear Creek,” he said.
The Public Works Department is paying for all of this through a 319 Grant, which was awarded to Boone County in part by Joe Machens Dealerships and the Missouri Department of Conservation. "The city is retrofitting a somewhat industrial facility with Storm Water Best Management Practices," said project civil engineer Erin Keys.
According to Heimos, this pavement costs a just a few dollars more than concrete pavement and requires a lot less to maintain, saying that the PaveDrain pavement will not need to be repaired as often and should be able to last at least twenty years.
This parking lot expansion not only helps out the department space problem, but is also a research test. “It’s a type of material that they wanted to try to see how it’s going to work. We did a lot of research and we believe it’s going to work just fine. But you know you have got to test things,” said Steven Sapp, public information specialist with the Columbia Public Works Department.
There is a worry that the sediment that is being filtered out of the water will get caught in between the bricks and cause a blockage for water to get through. The inventor of the pavement solved this problem. An attachment for a vacuum truck that is owned by the city was made so that the sediment can be sucked out from between the bricks. This will not have to be done often, according to Heimos, as the PaveDrain system does not clog easily.
This new system is being tested continuously to see if it is actually filtering out sediment and other pollutants and to measure the amount of drainage that is going through. This pavement can be painted and treated like traditional pavement.
This story originally aired as part of Under the Microscope, a weekly program about science, health, and technology in mid-Missouri.