Rainfall Volume on Stetson Parking Lot
As you can see the dimensions for the Stetson parking lot at Mercer University are 240 ft by 230 ft. With a 2 inch rainfall event, the total volume of water that falls on the parking lot is 9200 cubic feet. This is equivalent to 68,816 gallons of rainfall. This volume is about the size of seven backyard pools or 34,408 milk jugs. Overall, this is a lot of water runoff for one rainfall event. Since the parking lot is an impervious surface, about 98 percent of the total rainfall will runoff into the local storm water management system. If just one relatively small parking lot can produce this amount of runoff into the storm water system, imagine how much the treatment plant has to be able to filter through the system. All of the storm water for the city of Macon flows into two waste water treatment plants, Lower Poplar and Rocky Creek. The treatment plants have to be able to accommodate large storm water events as well as the typical waste water that is produced throughout the city. Basically, the two waste water treatment plants are filtering around 50 million gallons per day per storm event in the city. That is a lot of water.
