1 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 requi rements 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 generato rs and manufacturers to better understand the cooling water intake structure (CWIS) technologies in use at typical facilities, including the site-specific characteristics of each f acility and how these affect the selection and performance of CWIS technologies. EP A is also visiting facilities to better understand cooling water use and specific is sues or technologies that can affect 316(b) compliance. Canadys Station (Canadys ) was selected for a site visit due to

its use of a retrofitted recirc ulating 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 prop erty 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 th e river opposite from the generating station. Canadys employs 86 people and has been in operation

since 1962.

Cooling and process water withdrawals a nd wastewater discharges are currently regulated under NPDES permit numb er 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) wi th generating capacities of 125 MW, 125 MW and 212 MW, respectively. Units 1 a nd 2 are basically id entical and began operation in 1962 and 1964. Unit 3 is a one-of-a-kind Foster Wheeler oncethrough subcritical boiler th at began operation in 1967. 2 The fuel source for all

three units is Eastern Bituminous Co al 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 utilizat ion 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 faci lity’s heat rate is approximately 10,200- 10,300 Btu/KWh.

Each generating unit has two routine one to two week mainte nance outages that occur in the spring and fall. Typicall y, these outages are performed on a single unit, unless there is a task th at needs to be done at multip le 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 locat ed on the shoreline

of the Edisto River 4 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 exis ting CWIS to withdraw makeup water for the CCRS; actual intake flows are ap proximately 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 ex isting 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 outfa ll 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 th e 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 retrof itted a closed-cycle cooling system (CCRS) to each generating unit.3 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 towe r consists of ten cells in series. The tower array is 50 feet wide and extends 540 feet in lengt h. The facility was able to use the existing basin and pumps 8 when it rebuilt the system.

Also to address 316(a) concerns, in the early 1970s, the facility began experimenting with wooden “hel per 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) con cerns and because there was not enough volume in the Edisto River to provid e once-through cooling during low flow periods. 9 The ten cell GEA concrete mechani cal draft cooling tower has a backto-back configuration (five cells on each side) with f our fixed speed circulatingwater 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 st ate park on the other side, transmission lines, and abandoned on-site hous ing. 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 or der 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 othe r issues associated with retrofit including permitting, noise, air concerns, etc. The towers are also fitted with drift eliminators, but not plume or noise abatem ent. 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 repres entatives 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.4 down for an extended period to retrofit Un its 1 and 2. Canadys carefully planned the retrofit and arranged construction ta sks to minimize downtime; ultimately, the facility had an outage of 6 weeks for tie-in.

Each tower has a maximum evaporation ra te of 3 mgd. Therefore, the maximum amount of make-up cooling water requir ed 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 to wer, this 4 cell mechanical draft tower was replaced in 2000 with a fiberglass c ooling tower with five fixed speed 4,000 gpm recirculating pumps. However, in practic e, the facility oper ates 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 th e facility converted to CCRS for this application as well. Following this retr ofit, this facility’s operation was totally converted to closed-cycle cooling. Sin ce converting completely to closed-cycle cooling, Canadys had eliminated both its 316(a) issues (its permit no longer contains temperature limits) and its wate r shortage issues during low river flow periods.

Canadys uses biocides in each of its coo ling 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 ope ration 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 or ganics yielding increased O&M costs. 12 At one point, some of the fill material collapse d under its own weight. As a result, the facility now uses standard efficiency f ill material to reduce operating costs.

Facility representatives stated that Ca nadys has likely not experienced a reduction in power output as a result of the CCRS re trofit. 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 ex iting 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.5 the water in the river, improving the turbine back pressure and increasing generation.

7.0 Debris Handling

Canadys does not have signi ficant 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 fo r 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 pl ant 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 wa s eventually abandoned, as it did not remove sufficient heat, thereby intro ducing 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 fr om 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 c onstruction industry. They also noted increased competition to sell the ash as more facilities add scrubbers.6 The new dry ash system on Unit 3 has a capacity of 32,000 tons per year, but the system is still undergoing test ing 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 co ver and steel jacket. The ash pond is underlain with a naturally occurring, de nse, 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 exte nds 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 electro static precipitators while Unit 3 has a baghouse for particulate control. Unit 3 is equipped with low NO

x burners and

Units 1 and 2 have low NO

x “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 discusse d other nearby facili ties owned by SCE&G:

 Jasper Plant: The Jasper Plant (SCE &G’s newest facility) is a gas/oil combined cycle plant that has operate d as a closed-cycle plant since it began operating. Jasper obtains wate r from a municipal water supply for cooling tower makeup and other uses.

 McMeekin: This facility has been de termined 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 an d constructed as a closed-cycle system and withdraws its makeup wa ter 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 co al burned remains as ash; of th e remaining ash, about 80% is fly

ash.

14 The bottom of the ash pond is compri sed of an impermeable layer of clay.7 Attachment A--Lis t of Attendees

Paul Shriner, EPA Jan Matuszko, EPA Kelly Meadows, Tetra Tech Kevin Young, SCE&G, Canadys St ation Operations Manager Andrew Green, SCE&G, Canadys St ation Environmen tal Technician Michelle Camburn, SCE&G, Canadys Stati on Environmental & Safety Coordinator Kevin Wicker, SCE&G, Ca nadys Station Manager Steve Summer, SCANA Services, Cor porate Environmental Services Milton Quattlebaum, SCANA Services, Co rporate Environmental Services Mark Ferguson, SCANA Services, Co rporate Environmental Services8 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.