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Site Visit Report

McDonough-Atkinson Power Plant

5551 South Cobb Drive

Smyrna, GA 30080

February 11, 2009

1.0 Background and Objectives

The Environmental Protection Agency (EPA) is in the process of developing 

316(b) cooling water intake structure requirements that reflect the best technology

available (BTA) for minimizing adverse environmental impact for all existing 

power plants and manufacturing facilities. As part of this process, EPA staff is 

visiting electric generators and manufacturers to better understand the cooling 

water intake structure (CWIS) technologies in use at facilities, including the sitespecific characteristics of each facility and how these affect the selection and 

performance of CWIS technologies. EPA is also visiting facilities to better 

understand cooling water use and specific issues or technologies that can affect 

316(b) compliance. McDonough-Atkinson Power Plant (McDonough-Atkinson)

was selected for a site visit due to its use of a retrofitted recirculating cooling 

water system.

2.0 Facility Description

McDonough-Atkinson is located on a 357 acre site1along the Chattahoochee 

River just northwest of Atlanta, Georgia. The facility opened in 1965 and 

employs 134 people. McDonough-Atkinson is owned by Georgia Power and 

operates under NPDES permit GA0001431 which expired December 31, 2008. 

Georgia Power submitted its NPDES permit application in a timely manner and is 

awaiting renewal of its permit by the state.

3.0 Electricity Generation and Transmission

McDonough-Atkinson consists of two 245 megawatt coal-fired generating units 

with a CUR of approximately 80%. These units burn eastern bituminous coal 

from Appalachia. McDonough-Atkinson is essentially a baseload facility.

McDonough-Atkinson previously shared the site with the Atkinson Power Plant, 

as described in Section 6.0. Georgia Power has also begun a major repowering 

project at the site, as discussed in Section 8.0. The site name is now officially

Plant McDonough-Atkinson.

 

1 As discussed in Section 8.0 below, McDonough-Atkinson acquired 50 acres adjacent to the original 250-

acre site to construct new generating units.
2

4.0 Cooling Water System and Intake Structure

The cooling water intake structure (CWIS) for McDonough-Atkinson is located 

on the shoreline of the Chattahoochee River. The screen house consists of six 

intake bays that previously housed six coarse mesh traveling screens, as well as a 

shared trash rack. After the facility converted to closed-cycle cooling, three of the 

intake bays were closed and the remaining three were outfitted with a bulkhead 

and a fine mesh (3mm) Johnson wedgewire screen.2 The existing fish return 

trough is no longer used and the wedgewire screens are cleaned by an automated 

airburst system. Facility representatives noted that the wedgewire screens have 

operated well so far and that no maintenance has yet been required. The new 

design through-screen velocity is 0.5 feet per second (fps).

As discussed below in Section 6.0, McDonough-Atkinson converted from oncethrough cooling to closed-cycle cooling. Prior to the conversion, the facility’s 

design intake flow was 393 million gallons per day (mgd). Currently, the 

facility’s DIF is 19.9 mgd,3a 94.9% reduction in design capacity. Similarly, the 

facility’s previous actual intake flow (AIF) was approximately 317 mgd; the 

current AIF is approximately 6.4 mgd.

McDonough-Atkinson’s discharge point is several hundred feet downstream of 

the CWIS.

5.0 Impingement and Entrainment Information

McDonough-Atkinson has not conducted any source water characterization or 

impingement or entrainment studies.

6.0 Cooling Tower Feasibility

In the early 1990s, the Georgia Environmental Protection Division (EPD) 

conducted a water quality study in the Chattahoochee River. Several lawsuits 

followed, largely due to high nutrient content. In order to better accommodate 

economic development in the Atlanta area,4 Georgia Power opted to retrofit 

McDonough-Atkinson to closed-cycle cooling. A four year compliance schedule 

for construction was developed.

 

2 The existing trash rack was kept in place to protect the wedgewire screens. Facility representatives noted 

that this made installation of the new screens much more difficult. Additionally, the screens were not 

placed on rails; therefore any maintenance will be performed by divers. The facility selected wedgewire 

screens since the necessary capacity was much lower and it was expected that wedgewire screens would be 

easier to maintain. Georgia Power had also experienced good success with these screens at Yates, another 

Georgia Power Plant. 

3 The CWIS has 3 new makeup pumps, each with a DIF of 6.6 mgd. In 2012 when McDonough-Atkinson

is replaced by the gas-fired unit, the makeup pumps will be replaced by 3 new pumps with a total DIF of 

21.6 mgd.

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See Section 14.0 for more information.
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In February and April 2008, two mechanical draft cooling towers were brought 

online at McDonough-Atkinson at a cost of $96 million. The tower array consists 

of two 67 foot tall 10-cell towers (arranged in a straight line) with 200 horsepower 

fans. Due to the proximity of an interstate (1/3 mile away), nearby residential 

areas, and on-site transmission lines adjacent to the towers, plume abatement was 

added to the towers in addition to drift abatement for approximately $10 million 

in additional costs. Plume abatement adds an extra air box on top of a traditional 

tower; recirculated warm water pre-heats air drawn into the air box via adjustable 

louvers. This warms and dehumidifies the evaporated water exiting the top of the 

tower, reducing the plume. The louver system allows the facility to operate the 

tower with or without plume abatement. McDonough-Atkinson typically operates 

the plume abatement system on cold, humid days and noted that the system 

provides reduced cooling when plume abatement is required. The towers are not 

equipped with noise abatement.

Because space was extremely limited at McDonough-Atkinson, Georgia Power 

demolished its former Atkinson facility located on adjacent property and moved 

maintenance buildings. Construction of each tower took approximately 3 years 

and the tie-in for each tower and condenser required a 6-8 week outage, during 

which time other maintenance and upgrades were also performed.

To accommodate the conversion, the facility blocked the discharge point and 

added two circulating pumps to pump the water to the cooling towers. Due to 

concerns with existing infrastructure, much of the piping was routed above 

ground along the river. The piping moves underground at the screen house.

McDonough-Atkinson faced a number of challenges in converting the facility to 

closed-cycle cooling:

 Plume abatement: this was the first time any Georgia Power facility had 

installed plume abatement, requiring additional time for operators to learn 

proper operations and maintenance. Plume abatement also adds additional

cost and height to the cooling towers.

 Space constraints: Even with the demolition of the former Atkinson plant 

and relocation of buildings, the towers are sandwiched between 

transmission lines, buildings, the switchyard, and a railroad. 

 Tunnel strength: due to the long pumping path (from the old discharge 

point to the newly constructed towers), a new pump station was added on 

the riverbank atop the existing intake structure. To ensure proper flow, 

much larger circulating pumps than those previously used inside the plant 

were added. Unfortunately, the original condenser piping (from the CWIS 

to the condenser) was not designed as a high-pressure system. Because 

Georgia Power found retrofitting the existing pumps to withstand high 

pressures extremely difficult and costly at a previous retrofit, it wanted to 

avoid increasing pressures in the existing tunnels. Instead, McDonoughAtkinson built the new pumping system to pump water into the cooling 
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towers. However, water exiting the towers is gravity fed back into the old 

screenhouse and condensers maintaining the original tunnel pressures. 

 Power requirements: the new circulating pumps and cooling tower fans 

require approximately 10MW to operate. The facility’s station service 

system was unable to provide that much power, so a separate transmission 

line from the transmission yard was routed across the river and down to 

the new pump station.

 Water treatment: McDonough-Atkinson previously had no treatment 

processes, requiring a new learning curve for facility operators. Several 

chemical feeds were added (biocide [sodium hypochlorite], algaecide, and 

silt dispersant), creating new storage tanks and feed line conflicts. 

McDonough-Atkinson noted that they chlorinate the tower water with 

sodium hypochlorite in bursts. They close the cooling tower blowdown 

until the chlorine level is below detection. As a result, they do not

discharge until chlorination is complete. They indicated the system 

requires three to four times more chlorine than expected, but that they

typically operate at 3-4 cycles of concentration. Also, prior to cooling 

towers, McDonough-Atkinson did not adjust the pH of its ash pond water 

prior to discharge; it was combined with the cooling water prior to 

discharge at a ratio of 20:1 (cooling water: ash pond water). After the 

cooling tower retrofit, the facility now treats its ash pond discharges when 

necessary.

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 Underground piping: Because of the age of the facility, McDonoughAtkinson had no blue prints or information on existing underground 

piping. This presented a substantial challenge during retrofit. 

 Other surprises: the facility had to add a small pump in the screen house to 

supply service water to the existing Induced Draft Fan bearing coolers.

Facility representatives were unsure of the operations and maintenance (O&M) 

costs for the new towers, but did note that some costs were higher than expected.6 

Overall, the towers have functioned as expected.

7.0 Debris Handling

McDonough-Atkinson does not have significant problems with debris loading. 

The airburst system for the wedgewire screens appears to be adequate in 

addressing any debris concerns.

8.0 Repowering/Future Uses

McDonough-Atkinson is currently undergoing a major repowering project. 

Georgia Power purchased a large tract of land to the facility’s north and 

 

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In-line pH adjustment is used for treatment.

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For example, the towers are requiring more biocide treatment than projected. Since no tower blowdown 

is permitted during chlorination cycles, this leads to some minor operational difficulties. Typically, the 

tower cycles water 3-4 times before blowdown.
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constructing two 800 MW gas-fired combined-cycle units at the site. Both of 

these units will incorporate closed-cycle cooling. Once the first unit is 

operational, the power block at McDonough-Atkinson will be demolished7and a 

third 800 MW gas-fired combined-cycle unit will be constructed in its place; the 

second and third combined-cycle units will use the cooling towers built for 

McDonough-Atkinson’s existing units. A gas pipeline is currently under 

construction and scheduled for completion in summer 2010. The first unit is 

expected to be operational in early 2011, the second in summer 2011 and the third 

in summer 2012. This conversion will transform the site from a 500 MW facility

to a 2400 MW facility with significantly lower air emissions (in an urban nonattainment zone for ozone) and have minimal cooling water withdrawals.

Georgia Power also examined the possibility of using “grey water” from a nearby 

wastewater treatment plant (WWTP), but ultimately concluded that the operation 

of the cooling towers would serve to concentrate pollutants and make it more 

difficult for McDonough-Atkinson to meet its own discharge limits. Facility

representatives were also concerned about obtaining a consistent volume of flow, 

as discharges from a WWTP can vary seasonally.

9.0 Cooling Ponds

There are no cooling ponds onsite.

10.0 Ownership

McDonough-Atkinson is owned by an investor-owned company, Georgia Power, 

a Southern Company. Plants operated by Southern Company provide

approximately 95% of the electricity in the state, making them the single largest 

entity for promoting economic development in the state. Georgia Power’s rates 

are set by the Public Service Commission and any large expenditures would 

require approval before being passed along to consumers.

11.0 316(a)

McDonough-Atkinson was previously granted a variance from 316(a) 

requirements, but with the conversion to closed-cycle cooling, the variance is no 

longer necessary. The facility operates at a condenser cooling water delta T of 

approximately 15-18°F.

12.0 Ash Handling

Currently, the facility uses an ash pond. As noted in Section 6.0, the wastes were 

previously commingled with once-through cooling water. Once the cooling 

 

7 The first unit will more than replace the generating capacity of McDonough-Atkinson’s coal-fired units, 

as well as provide the necessary voltage support.
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towers were constructed, a new discharge point (with pH adjustment) was 

installed within the existing discharge structure.

As discussed in Section 8.0, McDonough-Atkinson is converting to natural gas. 

Once this conversion is complete, the existing ash pond will be decommissioned.

13.0 Air Emissions Controls

Currently, McDonough-Atkinson only uses precipitators and low NOx burners. 

As discussed in Section 8.0, McDonough-Atkinson is converting to natural gas. 

The new units will use Selective Catalytic Reduction (SCR) for emissions 

controls.

14.0 Additional Information

As discussed in Section 6.0, the water quality of the Chattahoochee River was a 

significant concern for the state, Georgia Power, and the general public in the 

early 1990s. McDonough-Atkinson is located approximately 40 miles 

downstream of an Army Corps of Engineers reservoir (Lake Lanier) that operates 

to meet a 750 cfs minimum flow in the Chattahoochee River just upstream of 

Plant McDonough-Atkinson, while maximizing its authorized uses, including 

flood control, navigation and hydropower. In 2008, drought led to a temporary

reduction of the minimum flow target to 650 cfs during non-critical winter 

conditions. Additionally, several municipal WWTPs and industrial discharges are 

located upriver of the facility. The river also serves as the primary source of 

drinking water for the Atlanta area, as well as a navigation channel below 

Columbus, Georgia. 

Lake Lanier discharges from the bottom of the reservoir, leading to consistent 

ambient water temperatures of approximately 50-60°F. As a once-through 

facility, McDonough-Atkinson previously warmed the water temperatures to 

approximately “normal” conditions; there appeared to be no adverse effects to 

aquatic life, even in low flow conditions.

The water quality study conducted by the state concluded that the WWTPs would 

need to dramatically improve waste treatment, as the dissolved oxygen content of 

the river was too low. The Chairman of Georgia Power, also the chair of the 

Business Roundtable (an organization promoting economic development in 

northern Georgia), became concerned that limitations on the WWTPs would 

ultimately slow (or even halt) growth in the Atlanta area by reducing the capacity

of the treatment plants and municipality’s ability to issue new sewer use permits.8 

A follow-on analysis determined that converting McDonough-Atkinson to closed-

 

8 By extension, this would also affect Georgia Power’s growth.
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cycle cooling would improve the waste assimilative capabilities of the river by a 

third to half, thereby reducing the burden on the WWTPs.9

Attachment A List of Attendees

Attachment B Aerial Photos

Attachment C PowerPoint Presentation (2/11/2009)

Attachment D Site Visit Photos

 

9 The treatment plants are continuing to make upgrades, but no longer face the same scheduling and cost 

constraints.
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Attachment A--List of Attendees

Paul Shriner, EPA Headquarters

Jan Matuszko, EPA Headquarters

Karrie-Jo Shell, EPA Region IV

Kelly Meadows, Tetra Tech

Bill Evans, Georgia Power

Donna Hill, Georgia Power
Copyrighted page/s removed. Copyrighted 

material is not available in Regulations.gov since 

it may not be reproduced without consent of the 

copyright holder. 

Please contact the EPA Docket Center, Public 

Reading Room to view this document. 

Address: 1301 Constitution Ave, NW 

Room 3334 

Washington, DC 20004 

Telephone: 202-566-1744 

Fax: 202-566-9744 

Email: docket-customerservice@epa.gov
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Attachment C—PowerPoint Presentation (2/11/2009)

Please see the attached materials.

Attachment D--Site Visit Photos 

Please see the attached materials.