By John Schaffner
The city of Sandy Springs presently has three major studies underway to determine how effective the stormwater management system is it inherited from Fulton County and the kind of investment the city needs to make to protect its residents’ properties from flooding .
Stormwater Utility Manager David Chastant points out, “Fulton County had a storm drainage system. The issue was how well it was maintained and the response to the citizens when they had requests. The citizens up here didn’t feel they were getting the service they wanted,” he added.
There essentially are three components to the stormwater system, explains city Public Works Director Tom Black. “You have a public system, a private commercial system and a private residential system. You can have a good flowing system that is sized properly and will accept the flow. But right next to it, you might have a residential system that was under-designed.”
The City Council has authorized three studies which presently are being implemented through the Public Works Department:
One is an inventory of the existing system and an assessment of the conditions of the pipes in the ground. Arcadis, an engineering consulting firm, was hired to work for the city on this.
“They started on the southern end of the city and are about halfway through the city with their inventory and assessment,” Chastant told the Reporter. “ That is just a physical assessment. It does not look at performance issues. …
“We just had a performance test,” he added, referring to the recent extraordinarily heavy rains and floods.
To date, the city has had a very aggressive maintenance program for cleaning storm sewer intakes. It was the major focus when the city took over the system.
The second is a watershed improvement plan. Brown & Caldwell was hired to do improvement plans for the Nancy and Long Island creek watersheds. The state Environmental Protection Division (EPD) asked the city to see if there are things that can be done to improve the water quality in those two basins.
“We are focusing on looking at existing detention ponds,” said Chastant. “We will look at ponds that are considered to be the city’s responsibility and see if we can improve the capacity of them so that they provide better detention and better water quality.”
The Public Works employee said there are about 1,200 ponds in the city, but most are not the city’s responsibility.
The third program is a flood plain study.
“One of the requirements is that we protect development below 100 acres in every watershed,” Chastant said. “They want us to look at the future 100-year flood plain. That means looking at the future land-use plan and, based on that, building out to that condition what would be the flow in a 100-year storm event.”
He said the city’s Flood Plain Management Ordinance has special regulations on where property can be developed.
“That is a whole lot stricter than the current flood plain that we have through FEMA [Federal Emergency Management Agency].” he stated. “The big task is to map that flood plain to know where regulations need to be applied,” he added.
There are 60 miles of streams in the city that will be studied. The team has competed the work in Nancy Creek and is pretty far along in Long Island and up into Marsh Creek. There are four major study areas and he said the flood plain study should be completed no later than June.
The city discovered that FEMA is updating its maps. “We want to get the technical work done by the contractor and give that to FEMA,” he said. “Then we will have some new regulated maps.” FEMA’s goal is to have new maps out for public review in September of 2010. The existing maps are 20 years old.
“We are fortunate that City Council is working toward getting a good product,” Chastant said. And willing to pay for it. The inventory study is costing just under $1 million, the flood plain study around $400,000, according to Chastant.
“Through this evaluation process, Chastant is going to start bracketing in some cost in general, to get some value of what is in the ground and the value of the issues that we know are going to need attention,” Black stated.
That is why City Council wanted us to do the inventory, to identify the issues and come up with some cost estimates on correcting our problems. That is where the big bucks will come in.
“However, the system is in better shape than I thought it was. So, the cost is not going to be as bad as it could have been,” he said. “You never will be done fixing the system. It is just a matter of setting priorities and fixing what needs to be fixed first.”
“We are going to have a good solid snapshot of what we have,” Black explained. “On top of that we will have FEMA maps that don’t conflict with our information because they are going to use our information to build them. It is unique for a jurisdiction to have that kind of information available,” he added.
“Click on a land lot and zoom in closer and you can see the infrastructure. You can see how it is inventoried, what it is worth, what condition it is in and then have a picture of the worst ones,” Black pointed out. “That will put us way ahead of the ballgame.”