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Site Visit Report 

Canadys Station 

 Highway 61/Route 15 

 Canadys, SC 29433 

February 10, 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 typical facilities, including 

the site-specific 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. Canadys Station (Canadys) was selected for a site visit due to 

its use of a retrofitted recirculating cooling water system. 

2.0 Facility Description 

Canadys is owned and operated by South Carolina Electric and Gas (SCE&G) and 

is located in rural Canadys, South Carolina. The facility property is a 1600 acre 

site that is split by the Edisto River and bordered by a state park. The vast 

majority of the site (approximately 80%) is on the side of the river opposite from 

the generating station. Canadys employs 86 people and has been in operation 

since 1962. 

Cooling and process water withdrawals and wastewater discharges are currently 

regulated under NPDES permit number SC0002020, which expired on June 30, 

2009.1

3.0 Electricity Generation and Transmission 

Canadys was originally designed as a four unit plant but only operates three 

generating units (Unit 1, 2, and 3) with generating capacities of 125 MW, 125 

MW and 212 MW, respectively. Units 1 and 2 are basically identical and began 

operation in 1962 and 1964. Unit 3 is a one-of-a-kind Foster Wheeler oncethrough subcritical boiler that began operation in 1967.2

 The fuel source for all 

three units is Eastern Bituminous Coal obtained from Kentucky and West 

Virginia.3

 

1

 As of March 15, 2010, the permit has been administratively extended. 

2

 Unit 3 was converted to a balanced draft unit and currently operates at approximately 185 MW. 

3

 99.9% of the fuel source is coal. The facility uses natural gas or fuel oil for start-up. 
2

The overall capacity utilization rate (CUR) at Canadys is approximately 50%. 

Generally speaking, Canadys is a baseload facility, but cycles its load to respond 

to peaks. Typically during turn down, Units 1 and 2 are operated at half-load 

while Unit 3 is run at 90%. The facility’s heat rate is approximately 10,200-

10,300 Btu/KWh. 

Each generating unit has two routine one to two week maintenance outages that 

occur in the spring and fall. Typically, these outages are performed on a single 

unit, unless there is a task that needs to be done at multiple units. The facility also 

has a 10 week turbine unit outage every 6 years for Unit 3 and every 7 years for 

Units 1 and 2. 

The transmission system is also owned and operated by SCE&G. 

4.0 Cooling Water System and Intake Structure 

Each generating unit originally had an individual CWIS located on the shoreline 

of the Edisto River4

 that provided once-through cooling water.5 Each CWIS was 

fitted with a standard (i.e., coarse mesh) traveling screen. Units 1 and 3 share a 

CWIS screen house, while Unit 2 has a dedicated CWIS. 

The original design intake flow (DIF) of the facility was 374 million gallons per 

day (mgd). Canadys still uses the existing CWIS to withdraw makeup water for 

the CCRS; actual intake flows are approximately 3-7 mgd. Facility 

representatives noted that its make-up water pumps are only fitted with a trash 

rack to keep out logs and other large debris. When the facility removed the 

traveling screens on the existing intake structures, they found substantial sand 

build-up. As a result, they did not fit the pumps with traveling screens. 

The primary discharge point (outfall 006) is located at the outfall of the ash/spray 

pond, as discussed in Sections 6.0 and 12.0. The prior discharge point for 

Canadys was a retention area several hundred yards downstream of the CWISs; 

discharged water overtopped a weir and flowed into the river, but this outfall 

(003) was eliminated in the summer of 2009. 

5.0 Impingement and Entrainment Information 

 

Canadys has not recently conducted any source water monitoring or impingement 

and entrainment studies. 

 

4

 The Edisto is very shallow (on the order of 5 feet) and sandy. 

5

 As discussed in Section 6.0, Canadys has retrofitted a closed-cycle cooling system (CCRS) to each 

generating unit. 
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6.0 Cooling Tower Feasibility 

All three generating units at Canadys employ a CCRS. Units 1 and 2 share the 

same cooling water system (CWS) and are serviced by a common cooling tower 

while Unit 3 has a dedicated CWS and cooling tower. 

In 1972,6

 Canadys retrofitted Unit 3 with a wooden mechanical draft cooling 

tower that operated with two fixed speed 55,000 gpm circulating pumps to 

alleviate 316(a) concerns.7

 In 1998, a portion of that tower collapsed and the 

facility built a new fiberglass tower that went into operation in 1999. The 

mechanical draft cooling tower consists of ten cells in series. The tower array is 

50 feet wide and extends 540 feet in length. The facility was able to use the 

existing basin and pumps8

 when it rebuilt the system. 

Also to address 316(a) concerns, in the early 1970s, the facility began 

experimenting with wooden “helper towers” for Units 1 and 2. 

In 1992, Canadys retrofitted Units 1 and 2 with a single, common CCRS for two 

primary reasons: to address 316(a) concerns and because there was not enough 

volume in the Edisto River to provide once-through cooling during low flow 

periods.9 The ten cell GEA concrete mechanical draft cooling tower has a backto-back configuration (five cells on each side) with four fixed speed circulating 

water pumps each rated at 30,000 gallons per hour. Canadys chose the back-toback configuration to best accommodate space limitations. At that time, space 

was limited by the river on one side, the state park on the other side, transmission 

lines, and abandoned on-site housing. The on-site housing is no longer part of the 

Canadys site. 

Facility representatives noted the biggest challenge in constructing the cooling 

towers for Units 1 and 2 was the existing land subsurface. The surrounding land 

is comprised of impermeable clay. In order to ensure that the tower basin was 

sound and that the river didn’t reach the basin, the facility drove piles 25 feet 

below ground. The facility noted no other issues associated with retrofit 

including permitting, noise, air concerns, etc. The towers are also fitted with drift 

eliminators, but not plume or noise abatement. No changes to the condensers or 

other elements of the generating units were required in the retrofit. 

Because Canadys is critical in providing voltage to coastal areas and to boost 

power for the Williams Station, there was no consideration of shutting the facility 

 

6

 Only 5 years after it began operations. 

7

 The temperature of the Edisto River upstream of the plant was higher than the allowable permitted 

discharge temperature. Facility representatives noted that no staff remain from this period, but surmise that 

the original cooling tower at Unit 3 was a helper tower. 

8

 The pumps are arranged with 6 feet between each pump center. 

9

 The facility conducted a study of water availability in the 1990s; it concluded that water availability was 

no longer a concern after converting to CCRS. The lowest flow conditions in the river are approximately 

100 mgd and the facility typically only withdraws about 7 mgd. 
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down for an extended period to retrofit Units 1 and 2. Canadys carefully planned 

the retrofit and arranged construction tasks to minimize downtime; ultimately, the 

facility had an outage of 6 weeks for tie-in. 

 

Each tower has a maximum evaporation rate of 3 mgd. Therefore, the maximum 

amount of make-up cooling water required is double that amount. Following 

retrofit, Canadys used the existing intake structures to obtain make-up cooling 

water.10

 

Canadys also utilizes a CCRS for its service water and for other equipment 

cooling. Originally built as a wooden tower, this 4 cell mechanical draft tower 

was replaced in 2000 with a fiberglass cooling tower with five fixed speed 4,000 

gpm recirculating pumps. However, in practice, the facility operates four of these 

pumps with a total flow of 16,000 gpm. The primary reason for converting the 

service water to a closed-cycle system was the sand in the Edisto River water.11 

The sand damaged some equipment, so the facility converted to CCRS for this 

application as well. Following this retrofit, this facility’s operation was totally 

converted to closed-cycle cooling. Since converting completely to closed-cycle 

cooling, Canadys had eliminated both its 316(a) issues (its permit no longer 

contains temperature limits) and its water shortage issues during low river flow 

periods. 

Canadys uses biocides in each of its cooling towers. The main additive is 12.5% 

sodium hypochlorite. The facility also adds a dispersant to its service water 

cooling tower. 

Facility representatives indicated that operation of the cooling towers was fairly 

smooth and that they had had few problems with the existing towers. They 

explained that the towers for Units 1 and 2 originally used high efficiency fill 

material, as this enables a design using fewer or smaller cooling towers. While 

high efficiency fill provides for lower capital costs, it requires more chemical 

treatment if the water contains organics yielding increased O&M costs.12 At one 

point, some of the fill material collapsed under its own weight. As a result, the 

facility now uses standard efficiency fill material to reduce operating costs. 

Facility representatives stated that Canadys has likely not experienced a reduction 

in power output as a result of the CCRS retrofit. Rather, they have seen an 

increase in power output because they were no longer limited by their previous 

summer to winter differential associated with 316(a) limits. They further 

explained that in the summer, the water exiting the towers is actually cooler than 

 

10 Makeup water for Units 1 and 2 is withdrawn from one CWIS and makeup water for Unit 3 from the 

other. There are two 5.2 mgd (3600 gpm) pumps for each CWS. 

11 Upon observing the river, sand is readily visible on the river bank. 

12 Facility representatives noted that makeup water from groundwater wells might have had lower 

concentration of organic material and been a better source of water for the towers using high efficiency fill. 
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the water in the river, improving the turbine back pressure and increasing 

generation. 

7.0 Debris Handling 

Canadys does not have significant problems with debris loading. As discussed 

above, the facility has a very low intake velocity and has removed its traveling 

screens. 

8.0 Repowering/Future Uses 

Canadys has no current plans for re-powering or expansion. 

9.0 Cooling Ponds 

There are no cooling ponds onsite. 

10.0 Ownership 

SCE&G is an investor-owned company. 

11.0 316(a) 

Canadys experimented with a spray pond to address 316(a) concerns associated 

with Unit 3. Using this technology, the plant piped the heated water from the 

discharge retention area and sprayed it into a pond, where it ultimately discharged 

upstream of the plant. The spray pond was eventually abandoned, as it did not 

remove sufficient heat, thereby introducing warmer and warmer water to the 

vicinity of the CWISs. The delta T at Canadys is approximately 19°F. 

As noted above, the facility no longer has thermal discharge limits in its NPDES 

permit. 

12.0 Ash Handling 

Units 1 and 2 have wet bottom ash handling while Unit 3 has a newly installed 

dry ash handling system. Bottom ash from the baghouses on Unit 3 is sent offsite and sold for “carbon burn out.” This ash has high carbon content. Some of it 

can be recovered by the receiving facility as heat and the resulting ash is a higher 

grade for re-sell. The facility noted the ability to sell fly ash had dropped along 

with the demand in the building and construction industry. They also noted 

increased competition to sell the ash as more facilities add scrubbers. 
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The new dry ash system on Unit 3 has a capacity of 32,000 tons per year, but the 

system is still undergoing testing and is not fully operational.13 The facility has 

the capability to off-load the ash dry or wet depending on the market. 

Wet ash is sluiced to a 95 acre ash pond on the opposite side of the Edisto River 

via a ceramic pipeline with a steel cover and steel jacket. The ash pond is 

underlain with a naturally occurring, dense, low-permeability geologic formation 

known as the Cooper marl. A low permeability, cement-bentonite “slurry wall” 

extends around the perimeter of the pond. The slurry wall is a vertical barrier 

(approximately 2.5 feet wide) which extends from the pond crest to about four 

feet into the marl.14 South Carolina solid waste permitting requires regular pond 

inspection. This facility does not employ the “wet stacking” technique done at 

TVA. 

13.0 Air Emissions Controls 

Units 1 and 2 are equipped with electrostatic precipitators while Unit 3 has a 

baghouse for particulate control. Unit 3 is equipped with low NOx burners and 

Units 1 and 2 have low NOx “pumpkin teeth” burners. The facility is not planning 

on installing scrubbers, but would be required to do so if it installed new units.

 

14.0 Additional Information 

 

Facility representatives also discussed other nearby facilities owned by SCE&G: 

 Jasper Plant: The Jasper Plant (SCE&G’s newest facility) is a gas/oil 

combined cycle plant that has operated as a closed-cycle plant since it 

began operating. Jasper obtains water from a municipal water supply for 

cooling tower makeup and other uses. 

 McMeekin: This facility has been determined to not be subject to the 

Phase II rule, as its cooling water is withdrawn from a hydroelectric 

facility penstock. 

 Cope: Cope Station was designed and constructed as a closed-cycle 

system and withdraws its makeup water from groundwater wells, although 

it also has the capacity of withdrawing water from a small river. 

Attachments 

Attachment A List of Attendees 

Attachment B Aerial Photos 

Attachment C Site Visit Photos 

 

13 Facility representatives noted that this capacity is based on the maximum annual output for Unit 3. 

Approximately 10% of the volume of coal burned remains as ash; of the remaining ash, about 80% is fly 

ash. 

14 The bottom of the ash pond is comprised of an impermeable layer of clay. 
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Attachment A--List of Attendees 

Paul Shriner, EPA 

Jan Matuszko, EPA 

Kelly Meadows, Tetra Tech 

Kevin Young, SCE&G, Canadys Station Operations Manager 

Andrew Green, SCE&G, Canadys Station Environmental Technician 

Michelle Camburn, SCE&G, Canadys Station Environmental & Safety Coordinator 

Kevin Wicker, SCE&G, Canadys Station Manager 

Steve Summer, SCANA Services, Corporate Environmental Services 

Milton Quattlebaum, SCANA Services, Corporate Environmental Services 

Mark Ferguson, SCANA Services, Corporate Environmental Services 
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Attachment B--Aerial Photos 

Please see DCN 10-6535A accompanying this document. 

Attachment C—Site Visit Photos 

Please see DCN 10-6535B through KK accompanying this document.