Residents unhappy about “wet” retention ponds placed in neighborhoods, such as the one recently built off Jackson and Shephard streets, may be disappointed to find out such ponds are built out of legal necessity.
Though residents adjacent to that pond offered such concerns as how the pond could be an attractive nuisance, a mosquito haven or simply unsightly, City Engineer Travis Drake explained at last week Wednesday’s Plan Commission meeting that these ponds are being built to meet state DNR standards.
And, he added, though some other options exist, the one that best answers the DNR’s requirements to remove “suspended solids” from runoff is a wet pond, such as the one Alliance Laundry Systems has built.
In kicking off his discussion, Drake explained the DNR focuses on quality of storm-water runoff, not quantity, meaning its aim is to remove contaminants from runoff more than control how much runoff is occurring.
“In their quality control, they measure by ‘removal of suspended solids.’ Their standards is 80-percent-fewer suspended solids leaving the site than if there were no controls,” he said.
In some communities, this can be achieved by creating a water infiltration area, he noted, where water simply soaks back into the ground.
“In Ripon, infiltration is almost always not an option, because of our soils. We have heavy clay soils, and they do not infiltrate; they will hold the water [on the surface],” Drake said. “So their next best management practice is a retention pond. It retains the water. To get the most out of the settlement, they want at least 3 foot of water in the bottom of the pond — that’s why they’re wet. That’s why 3 feet of water is there.”