A handful of Sandy Springs residents who live in the Nancy Creek Basin discussed their concerns about flooding during an open house on proposed stormwater text amendments to the Nancy Creek Declared Sensitive Area.
The city’s stormwater ordinance requires new development to enable infiltration of 2.4 inches of rainfall to prevent soil erosion into the stream to reduce flooding in the Nancy Creek Basin. That is twice what is required for the rest of the city. It applies only to the part of the basin west of High Point Road.
Community Development Director Ginger Sottile said the proposed exemption allows up to 500 square feet of minor replacement work, which allows typical maintenance and routine repairs.
After presenting the proposal to City Council, staff read public comments and came back with the suggestion of swapping some existing coverage to help people who live in the Nancy Creek Basin, she said. The object is not to make anything any worse, she said.
A resident asked why a deck that allows water to go through is considered equivalent to concrete.
City Engineer Jon Amsbury said the deck is not 100 percent impervious.
“It doesn’t really percolate in that soil because the soil gets compacted. It gets hard because nothing ever grows on it so it doesn’t absorb water the way we are trying to get water to be absorbed into the ground for runoff reduction,” he said.
Residents asked about using permeable pavers on driveway to help with stormwater infiltration. But Ambsury said driveways also fail to absorb water even if permeable pavers are used, he said.
“It’s like a well-beaten path,” he said. After heavy use, the rainwater runs off the dirt since it’s so compacted.
He said the city does not consider gravel or pea gravel, chip slate, or any of those kinds of materials permeable.
But even in the Nancy Creek Designated Sensitive Area, homeowners can replace an existing driveway.
“It’s very important to understand that it has to be exactly the same. So the exact footprint, you rip it up, put it back down with new concrete or pavement,” Sottile said.
If the size of the driveway increases or goes into an area it didn’t before, then the homeowner must provide additional stormwater infiltration.
The residents continued to question city staff on being left out of the flood plain and the Designated Sensitive Area.
Sallie Duncan of Meadowbrook subdivision said her property has never been close to what’s defined as the flood plain.
“But I’ve seen the flooding. And I will never get rid of our flood insurance now,” she said.
Chris Laird, who lives east of Ga. 400 on East Powder Horn Lane off Windsor Parkway, asked why his property was outside of the Designated Sensitive Area.
“We’re having discussions internally about expanding the area but we haven’t gotten very far with those discussions yet,” Sottile said.
Amsbury said because Nancy Creek is more channelized east of Ga 400, it may have been left out of the Designated Sensitive Area. The topography of the Nancy Creek Basin on the west side of the highway flattens out more, so it affects a larger geographical area with flooding.
“Come over the next time it floods and we can have that debate,” Laird said.
The proposed changes must go before the Planning Commission and then the City Council for consideration and possible approval, which will happen in March or April.
