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Six inches of pervious concrete was laid over a recharge bed that varied between 24 and 30 in. In areas where pervious slabs met sections of asphalt, Geary's crew installed a woven geo-textile mat to keep water draining straight down through the pervious and recharge bed to avoid water seeping under the asphalt, which might cause the asphalt to fail prematurely.

Geary says the key to success on any pervious concrete job is in the planning. "If you properly plan things, it will succeed," he says. "Once the truck arrives on the job, you have to have everything ready for the pour." Geary also thinks the NRMCA certification program for pervious concrete should be mandatory for anyone that installs pervious concrete.

He adds that curing is very important on pervious jobs due to the low water/cement ratio. Curing requires the application of a poly sheeting on top of the slab, which remains in place throughout the course of the cure, approximately seven days. "The NRMCA suggests 20 minutes between the time the mix leaves the truck to having the poly over it," Geary explains. "We try to cut that time in half if possible."

Geary had seven men working on the paving line for the parking lot job. The process moved quickly, with two men on the roller screed, four moving the concrete as it came out of the truck and one jointing and applying the poly. Expansion joints were rolled using a special pervious joint roller from Bunyan Industries.

After one winter with Wisconsin's freeze-thaw conditions and heavy snowfalls, Geary says he hasn't seen any negative effects on the pervious concrete. The pervious was plowed with conventional equipment - no special plow blades were used. Due to the large amount of snow in February and March, and no place to go with it, the snow was pushed into a large pile on the pervious concrete. The pile slowly melted well into the spring with the water draining back into the aquifer rather than running off site.