The photo & link above is an abbreviated section of the full Emergency Action Plan telling local authorities and residents what to expect in the case of a dam rupture at the Scott Candler Reservoir. It is not a fun read but for residents and local jurisdictional governments, this topic needs to be discussed, reviewed and possibly improved upon.
Dunwoody and most of DeKalb County gets its clean water from the Scott Candler Water Treatment Facility located in Dunwoody between Winters Chapel and Peeler. When you drive east on Peeler past Tilly Mill, you see the beautifully landscaped path along the water works, you see the two huge pools of water sitting down below street level that holds millions of gallons of water from the Chattahoochee. But what you don't see from the street level are the two huge dams (55 & 59 ft tall) holding back a torrent of water that if released, due to dam failure, would quickly wash away numerous homes in the Dunwoody North Community.
If the dams were to rupture, a tidal wave of catastrophe would roll along the Nancy Creek Tributary all the way to 285 then on to Murphy Candler Park and beyond where it would finally flood the Marist School in Brookhaven. Based on the attached engineering study, a dam failure would wipe out numerous homes, apartment complexes & businesses where it would put many of my friends and neighbors under up to 27 feet of water. It would easily be a Billion Dollar catastrophic disaster and the DeKalb Water System would then need to be rebuilt as the County's main water supply would be out of commission. This loss of important infrastructure would cripple our County economically and threaten the heath and safety of all residents. DeKalb County has the responsibility to ensure dam stability and they hire an outside dam inspection firm every two years to file a report with the State. The County also has the responsibility to have an Emergency Action Plan (in case of rupture).
As an elected representative of the people of Dunwoody, I decided to ask for proof of compliance for Dam Inspections as required by the State in an email to DeKalb Watershed, where Commissioner Robert Patrick and the State Environmental Protection Division were also copied.
Reading various newspaper articles and other reports that concerned me regarding general maintenance on the facility, I sent the email below asking questions about dam safety about clean water tank safety as the linked report stated that the Scott Candler facility had 3 steel reservoir tanks built from 1950 to 1970
that were responsible for holding 15 million gallons of potable water.
That water was then dispersed to DeKalb County for customer use. In
2018, the 2nd reservoir tank’s roof started to
collapse in on itself. Scott Candler Water Treatment Facility
(SCWTF) set out to rebuild these old tanks and extend their lifespan. The
tanks would have their coatings stripped, any damage discovered would
be repaired, and the old roofs on tank 2 and 3 would be removed
and replaced. The coatings would then be replaced both inside and
outside to prevent any future rusting on the tank.
Finally because I work in chemical safety processes everyday for my full time work, I asked about their processes for chemical safety.
From: John Heneghan <John.Heneghan@dunwoodyga.gov>
Sent: Friday, December 16, 2022
To: Hayes, David E. <DEHayes>;
Griffin, David <David.Griffin>; Robert Patrick <rjpatrick
Subject: Questions regarding dam inspections & Emergency Action Plan
at Scott Candler Water Treatment Dams
Mr. Hayes, as the interim Director of the Watershed Management of DeKalb County, I will direct this message to you for reply but I am also copying in Commissioner Patrick, Dunwoody City Manager Eric Linton and State DNR representative Mr. Griffin for awareness and in case they can assist.
It has been a few years since I have been on the Scott Candler Water Treatment Facility property for a tour and it might be time to do it once again for Dunwoody folks when appropriate. Until then, I am raising a few questions related to the safety of the neighbors to the water treatment facility that I would like answered. I have no reason to be concerned specifically related to this facility but a news story in Atlanta Magazine entitled "In the Flood Zone" has raised my general concern, and then a few internet searches later, I am now forced as an elected official to assure myself of my communities safety & long term well being.
Based on a recent story in Atlanta Magazine (December 2022 edition) and a historic newspaper article from 2017 specifically highlighting the Scott Candler Water Treatment Dams, I am interested in reviewing the latest Dam inspections for Scott Candler Reservoir #1 and Dam #2 that may be dated 02/04/21. I would also like to read the condition assessment dated the same date and I would also like to read the 2023 evaluations / inspection when complete in 2023 as the two year reinspection would be due in February. Based on the height and volume behind the dam, I consider the Scott Candler dams to be high-hazard but the attached spreadsheets may not show this to be true? That being said, I am also interested in reading the latest Emergency Action Plan for possible dam failure at the Scott Candler Water Treatment Facility.
I know there are huge water storage tanks on the property and besides the safety inspections of those tanks, I am interested in the mitigation structures that may be installed (raised containment berms to hold all the liquid) as I want to be assured that plans are in place to protect the neighboring residents from the water in those tanks.
Finally, I am interested in knowing about the chemical stored / used on site. Does the facility use Chlorine Gas in the processes or does it use the safer Sodium Hydrochloride Liquid? If using the gas, I am interested in your emergency plan for residents if there was a large-scale release of gas? If using gas, are the internal storage tanks of Chlorine refilled on-site ? If using gas, does the gas come in large ton tanks or in large / long steel cylinders? I ask because I am concerned in the amount of Chlorine gas being stored on site.
Thanks
John Heneghan, Mayor Pro Tem
Dunwoody City Council
Kudos and thank you to DeKalb County, both Watershed Management and the Administration (Zack Williams), as well as County Commissioner Robert Patrick for ensuring our safety to make sure these dams are safe and for providing documentation and answering my questions. It is appreciated.
Kudos and thank you to Mr. David Griffin of the Georgia Environmental Protection Division for also ensuring our safety (by staying after DeKalb) to make sure these dams are safe and for providing documentation and answering my questions.
I was informed that both Scott Candler #1 and #2 are high hazard dams. They are not included on the HHPD eligible dams list because the dams on that list are dictated by requirements from FEMA for a specific grant program. The State EPD provided the copy of the engineer inspection from 2021 and the Emergency Action Plan for these dams. Note that an inspection for 2023 has not been submitted yet, and is not due until April 30, 2023 - but I will request it when appropriate.
I was informed the county does not house nor use Chlorine gas at the water plant. They do in fact use the safer Sodium Hypochlorite to maintain disinfection in the distribution system. There are 3 ground storage water tanks on site that can each hold up to 5 million gallons of water. These tank have been recently rebuilt to ensure they are structurally sound.
Overall I am glad DeKalb has a dam inspection survey on hand, and that they have an Emergency Action Plan but I am disappointed that the EAP did not mention the City of Dunwoody, nor coordination with the Dunwoody Police. City of Dunwoody Communications team should also be ready to share grim Emergency news via reverse 911 and other means available. DeKalb County Emergency operations might want to do a table top exercise testing how emergency services might work if the dams were breached.
I will be requesting that the City Manager and Police Chief have the appropriate staff review the Emergency Action Plan, possibly meet with DeKalb Emergency Operations and ask that the EAP plans be updated with Dunwoody information where appropriate.
I pray those dams never fail! I hope DeKalb County follows the law and operational best practices when it comes to maintaining & inspecting those dams so that they can last for many, many more years.
I hope the affected residents are aware of the slim possibility that severe flood damage to their property is possible. I hope that residents study the included flood maps for situational awareness because someday a reverse 911 or other emergency message may be given and that should not be the first time for residents to hear of this threat.
We need to hope for the best but plan for the worst and when it comes to important safety activities being conducted by a governmental entity, we trust but verify.
John
