Final Notes from Site Visit at South Carolina Electric & Gas Co mpany ’s McMeekin Station on January 25, 2013

EPA conducted a site visit at South Carolin a Electric & Gas Co mpany ’s ( SCE & G ) McMeekin
Station (McMeekin ) located in Columbia, S outh C arolina on January 25, 2013

, to learn about the operations at the plant , specific ally the dry combination vacuum / pressure bottom ash handling system

. These notes describe the information collected dur ing the site visit. Table 2 , located at
the end of these notes , identifies the site visit participants. The summary and block diagram of the dry bottom ash handling system that the SCE&G personnel supplied during the site visit are provided as Attachment 1 to these notes.

Plant Overview

• McMeekin operates two pulverized

, coal

- fired generating units at the power plant. Units 1 and 2, which began operation in 1957 and 1958

, respectively, each have a gross generating capacity of 125 megawatts (MW). Both gener ating units are operated as baseload units. Table 1 contains some general information for the two generating units.

Table 1. McMeekin Station Units Operation

Unit Installation
Date Gross Capacity

(MW) Particulate
Control NOx Control

1 1957 125 Fabric filter
b aghouse Overfire Air ( Nov 2004), Low NOx Burners (May 1999)

2 1958 125 Fabric filter baghouse Overfire Air (Dec 2004), Low NOx Burners (July 1999)

• McMeekin is located at the base of the Saluda Dam

. The dam was originally built
in the 1930’s to keep Lake Murray full. In 2002, as part of the Saluda Dam Remediation project, SC E&G constructed a backup dam as a prevent ative
measure in case of a dam failure due to the presence of fault lines in South
Carolin a . As part of the Saluda Dam Remediation project, s everal changes were
made to plant operations in 2002 including a dry conversion of both the fly and bottom ash handling systems on both units

.

• McMeekin converted the wet sluicing fly ash and bottom ash handling systems to dry sy stems as part of the Saluda Dam Remediation project becau se of space
constraints and operati on and maintenance costs associated with the wet sluicing systems. McMeekin initial ly converted to a dense phase dry system between 2002
and 2003 . McMeekin then rep lac ed the dense phase dry bottom ash conveying system with a dilute phase, vacuum / pressure system in 2007 (Unit 2) and 2008 (Unit 1)

.

• Specifically, the sluice lines transferring fly and bottom ash sluice from the plant to the ash ponds ran along the origi nal dam; therefore, these pipes would havePage 2

needed to be relocated to continue sluicing to the ash pond s . McMeekin evaluated realigning the piping; however, it was determined that the resulting sluice system may not be reliable and could potentially require significant maintenance. Additionally, the ash pond receiving the sluice was determined to be the only footprint large enough to stage the stone pile and mixing equipment required by the contractor building the dam. Therefore, McMeekin ceased a sh s luicing to the ash ponds in the fall of 2002. The plant began d ewatering and closing the pond in
October 2002 and the closure was physically completed by June 2003 for the tw o primary ash settling cells. The plant dewatered a third “polishing pond” cell in
December 2003 and closed the cell between December 2003 and September 2005. The ponds were administratively certified as closed in November 2005.

• McMeekin retrofitted both units with completely dry fly ash and bottom ash systems in 2002. McMeekin instal led a dry, dense phase pressure system to pneumatically convey fly ash from both units to one of two fly ash silos, with wet and dry unloading capabilities. McMeekin initially installed a similar dry, dense phase pressure system to pneumatically convey bot tom ash from both units to one
bottom ash sil o. However, d ue to operation and maintenance issues , McMeekin retrofitted the original dry bottom ash system to a dry, dilute phase combination vacuum/pressure system in 2008 , as indicated previously

.

• McMeekin operates fabric filter baghouses to control fly ash and particulate emissions from the plant. McMeekin installed overfire air technology on both
units to control nitrogen oxide (NOx) emissions from the plant in December 2004

. Additionally, the boilers ar e operated with low

- NOx burners, which were installed
in 1999.

• Lake Murray is the source of the intake water at the plant.

• McMeekin currently stores approximately 100,000 tons of coal on site. At full load, the plant burns 1,800 to 2,000 t ons of coal per day. The ash content of the coal is approximately 8 to 9 percent , 12 percent maximum ash by contract

. The
coal is Central Appalachian bituminous supplied by Arch Coal and Peabody Coal

.

• McMeekin burns oil only during startup operations.

• McMeekin is currently planning to convert the two coal

- fired units to 100 percent

gas

- fired units by modifying the gas burner arrangement on these existing
burners. The boiler s are already designed to co

- fire coal and gas , and t he fuel
conversion is c urren tly planned for 2015. Additionally, McMeekin is scheduled to
retire these two units in 2018 when SCE&G

- owned nuclear units at another location begin commercial operation

.

• McMeekin currently sells 100 percent of its fl y ash to cement and block
manufacturers. In the event that fl y ash is not sold

, it is stored in a class 2 unlined

, onsite landfill. Currently, the plant does not sell bottom ash and all of it is storedPage 3

in the onsite landfill. The landfill was in itially brought onl ine in 1987 . After construction of the dam, McMeekin utilized the closed ash pond footprint to expand the landfill

.

• McMeekin installed l ow NOx burners on Unit 1 in May 1999 and on Unit 2 in July 1999. The plant installed o verfire air for Unit 1 in Novembe r 2004 and for
Unit 2 in December 2004. Since December 31, 2008

, McMeekin ha s been

con tinuously firing in SOFA (separated over fire air) mode, the lowest NOx
emission mode for these units.

Ash Handling Conversions

– Timeline and Background

• McMeekin conve rted the fly and bottom ash handling systems as part of the Saluda Dam Remediation project. SCE&G started evaluating the possibility of building the backu p dam after concerns about potential earthquakes (fault lines run through South Carolina) were raised in 1999. The plant started considering alternative ash handling options in 1999 through 2000

.

• SCE&G hired a consultant to develop a master site plan for the plant in 1999. As part of the site plan, SCE&G determined that the current ash pond would need to close and be transformed into a stock pile and staging area for dam construction

. The ash p ond was dewatered

, the ash was moved to an onsite landfill

, and the pond was backfilled. Initial dewatering of the pond took approximately two months , during which time SCE&G was removing ash and continuous ly pumping
the remaining water out of the pond

. In addition to the fly ash and bottom ash sluice water, t he pond also stored discharges from coal pile runoff (CPR) and low volume wastes (LVW) ; therefore, SCE&G dete rmined that two new

, smaller ponds, for CPR and LVW , would need to be constructed closer to the plant. The site plan also outlined the approach for relocating buildings that were obstructing the footprint of the backup dam structure.

• In 2000/2001, McMeeki n posted a request for proposal to convert the fly ash and bottom ash systems from wet sluicing systems to dry handling systems.
McMeekin determined that having the same vendor supply both the fly and bottom ash handling systems was important to make the conversion process more streamlined (i.e., only ordering parts from one vendor)

.

• For the fly ash sys tem, McMeekin evaluated a dense phase pressure and a dilute phase vacuum system. Based on the cost savings for piping (4” piping for the dense phase pressure system versus 8”

- 10” piping for the vacuum system), McMeekin decided to install the dense phase pressure system.

• For the bottom a sh system, McMeekin evaluated a dry conveyor belt system, a screw conveyor system, a complete recycle system, and a dense phase pressure system. McMeekin did not install the dry conveyor belt system due to space
constraints underneath and around the bottom of the boiler. McMeekin did notPage 4

install the screw conveyor due to the high estimated installation, operati on , and
maintenance costs. Due to space constraints and operating costs, McMeekin did not install a complete recycle system with hydrobins for bottom ash dewatering. Additionally, the installed horsepower for the complete recycle system was twice as much as a wet sluicing system and three times as much as the dry pressure systems evaluated. Therefore , based on the space constraints and an economic
eval uation, McMeekin selected the dense phase pressure system for the bottom ash handling conversion in 2002.

• The specific space constraints the plant encountered with the dry conveyor belt system included the following: space undern eath the boiler, the coal mills
between the boilers, and space for the inclined conveyor. After considering the constraints, the vendor could not guarantee the operation of the system.

• In 2002, the dam contract was awarded to an outside contractor that would
construct the dam and close the ash pond. T he ash systems were being installed at this time . As a result of these two construction projects, the plant was o ffline in
the fall of 2002 for a 10

- 12 week outage. The maintenance outage extended longer tha n 10

- 12 weeks to complete co nstruction of the dry fly ash and bottom ash handling systems.

• During this outage, the plant severed the lines for the CPR and LVW waste

streams previously directed to the ash pond. To anticipate this cut off, the plant constructed a CPR pond in 2000 and a LVW pond in 2003 closer to the plant to receive the wastewater once the ash pond was closed.

• In early 2003, the plant was up and running with the new dry ash handling systems. As previously stated, d uring this outage , the plant started dewatering

, dre dging, and closing the ash pond for preparation for the dam construction

.

• In 2008, McMeekin determined that a change to the bottom ash handling system was required due to issues with the dense phase pressure system installed in 2002

. McMeekin converted the bottom ash handling system to a dilute phase combination vacuum/pressure system. With this system, the leaner bottom ash particles were moved at a higher velocity

. Although the dense phase pressure system moved a higher quantity of bottom as h at a single time

, there were issues associated with this system, includ ing frequent clogging due to an inconsistent mix of the bottom ash particle size. In addition, pipes in this system needed to be changed every three years, either by rolling the pi pe 180 degrees or replacing it. The plant selected the dilute vacuum /pressure system because it was more efficient compared to dense phase transport systems

.

Bottom Ash Handling

• In 2002, the plant converted the wet sluicing bottom ash handling system to a dense phase dry pressure system. As part of the conversion, the plant completelyPage 5

changed out the hoppers underneath the boiler for the dry system. The bottom of
each boiler was e quipped with five refractory

- lined hoppers. As part of the wet hopper re moval, the plant excavated a 36

- inch pit to accommodate the eq uipment for the dry bottom ash system

.

• As part of the bottom ash retrofit in 2002, McMeekin decided to keep the wet seal on the hopper compared to changing to a dry seal. Switching to a dry seal was desired, but it was challenging to install due to the stainless steel components and

a temperature design criteria of 1200°F.

• In 2007 ( Unit 2 ) and 2008 (U nit 1 ) , McMeekin remove d all the dense phase pressure system equipment that transported the bottom ash from d irectly underneath the five refractory lined hoppers to the bottom ash silo ; however, the five refractory lined hoppers remained intact . The plant then install ed the dilute phase combination vacuum/pressure system

. The Unit 2 retrofit in 2007 was completed within a scheduled 8

- 12 week outage , and the ash handling retrofit was

not the driver for the length of the outage

. The Unit 1 retrof it in 2008 was completed in a four week outage

, along with other scheduled maintenance work

.

• For the new combination vacuum/pressure bottom ash handling system, the
bottom ash is collected in the same fiv e refractory

- lined hoppers located under
both units installed in 2002

. Both un its have identical eq uipment underneath the hoppers. “ B om b bay doors ” at the bottom of each hopper are operated to drop
bottom ash into a single roller crusher , where larger bottom ash pieces are crushed for entry into the vacuum sys tem. The plant operates a swing disc gate to drop the bottom ash from the crusher into the vacuum system conveyance line. The dry system uses a forced draft (FD) fan to cool the collected bottom ash as it is
crushed and fed into the vacuum system

. The “ bomb bay doors, ” crusher, and swing disc gate structures require approximately six feet of space underneath the hoppers to the conveying line

.

• The bottom ash from each unit is conveyed by vacuum from underneath the boiler

to one transfer station approximately 150 feet away. There is a vacuum transport pipe from the bottom of each unit that combines at a “Y” junction point prior to entering the transfer station. The forks of the “Y” represent the unit specific transport pipes from each unit that combine prior to the transfer s tation . The
remain der of the piping from the “Y” junction to the transfer station is shared for
both units. Because of the piping and vacuum configuration, McMeekin only pulls bottom ash from one unit at a time.

• At the transfer station, which is equipped with a bag filter , the vacuum is
exhausted to the atmosphere

, and the bottom ash drops into Nuva F eeders . Nuva
Feeders are bins where the air source switches from vacuum to pressure. McMeekin estimates that the bag filter at the transfer station is changed once every five years.Page 6

• The bottom ash is transferred by pressure from the transfer station to the bottom
ash silo . The piping for the pressure portion of the system runs 50 feet
hori zontally to the bottom ash silo then runs vertically up the bottom ash silo approximately 90 feet.

• Bottom ash from bot h units is transferred to a 300

- ton silo that the plant estimate s to be approximately 8

- 10 days worth of bottom ash storage. T he plant stated that
the moisture content of the bottom ash inside the silo is e ssentially zero

.

• The bottom ash is then moisture conditioned to approximately 19 % using a pugmill unloader . The moisture conditioned bottom ash is loaded from the silo into a dump truck and transferr ed to the onsite landfill. McMeekin uses filtered service water from Lake Murray for moisture conditioning the bottom ash to
reduce fugitive dust

. McMeekin estimates that the bottom ash silo is emptied
three times a week and transferred to the onsite landf ill.

• The bottom ash silo is equipped with both a pugmill unloader for moisture conditioning ash and a vacuum spout unloader for completely dry unloading. Although the bottom ash silo is equipped with completely dry unloading,
McMeekin has never unloaded b ottom ash completely dry

.

• As part of the second bottom ash conversion in 2008, the plant replaced the carbon steel piping from the hoppers to the transfer station and silo with new, more robust Nuvalloy piping with d urite wear sections and ceramic

- lined e lbows.
McMeekin estimates that the new pipes need to be ro tated or replaced every three years to prevent wearing. When bottom ash is not cooled enough by the FD fan, the high temperature of the bottom ash can have negative effects on the piping.

• McMeekin explained that the dilute combination vacuum/pressure system installed in 2008 operates well. The system plugs less often than t he old dense phase dry handling system . When a plug occurs, plant personnel locate the plug with an infrared temperature sensor and unplug the piping

. The plant does not
have to take the units offline for this type of maintenance.

• McMeekin would have installed a vacuum

- only system to transfer the bottom ash
in 2008 ; however, the cost to remove all of the equipment from the previous pressure system (i.e., the silo and the mechanical blowers) and install a completely new vacuum system was considerably more expensive than altering the dry bottom ash system to be a dilu te phase, combined vacuum/pressure system. Switching air sources from vacuum to pressure can result in a loss of conveying power and causes problems with some of the valves and seals within the system. The plant installed the vacuum/pressure system because the existing ash silo was designed for pressure conveying and would have been more costly to replace than it was to add a pressure stage to the conveying system.Page 7

• McMeekin started burning low

- sulfur coal approximately a year prior to the site
visit to mee t air emission regulations. The higher sulfur coal was caus ing plugging issue s in the bottom ash handling system , though the cause is not
known

. Since the fuel switch, McMeekin has not had many problems with plugging , although occasional plug ging still occ ur s , specifically in the plug

- prone vertical length of piping prior to the bottom ash silo.

• According to plant personnel, s witching from wet sluicing to the dry bottom ash handling systems has resulted in operation and maintenance cost savings at McMeekin because the plant is not pumping water through pipes and valves that wear over time, across the plant property to the ash pond . For the new dilute phase combination vacuum/pressure system

, the only maintenance so far has been rotating or replacing piping.

• McMeekin personnel stated that the dense phase pressure system required significant time and man power for unplugging lines

, fixing inflatable seals that became problemat ic because of the temperature of the bottom ash , and “babysitting” the syste m

.

• At the time of the initial 2002 conversion to the dense phase dry bottom ash pressure system, McMeekin installed a secondary collection system for the mill rejects and pyrites. This system was a similar dense phase dry pressure system that emptied into a small storage silo prior to being sent to the bottom ash silo. Because the mill rejects and pyrite s ar e more uniform in particle size, a retrofit to
th e combination vacuum/pressure system was not necessary in 2007/ 2008. Therefore, McMeekin operates the original pressure system and transfers the mill rejects and pyrites to a pyrite silo adjacent to the bottom ash silo for disposal.

Fly Ash Handling

• In 2002, McMeekin installed a dense phase dry pressure system to transport dry fly ash to one of two dry fly ash silos. The fly ash is collected in fabric filter baghouses from each unit that were installed in 1994

. Prior to the fabric filter baghouses, the plant used electrostatic precipitators to collect the fly ash. During the conversion in 2002, McMeekin removed the sluice pumps and changed out the piping from underneath the hopper for the dry pressure system.

• In 2002, the fly ash conversion was designed to convey dry fly ash by pressure from each unit, separately, to two fly ash silos approximately 600 feet away from the hoppers. Although the conveying lines are separate, McMeekin designed the system to have the option to transfer dry fly ash to either one of the two 650

- ton fly ash silo s from both units

.

• The fly ash silos are both equipped with moistur e conditioning unloading equipment and completely dry unloading equipment. McMeekin moisture conditions the dry fly ash with filtered service water from Lake Murray to 19Page 8

percent moisture ( an approximate value based on desig n specifications for the system) to control fugitive dust at the landfill if it cannot be marketed

.

• Although McMeekin has two dry fly ash silos, currently, the plant se lls 100 percent of the dry fly ash to a separate company that re

- burns the fly ash with a stage turbulent air reactor (STAR) to achieve a lower loss on ignition (LOI) . The final LOI, after the STAR, is approximately one percent

. The fly ash from
McMeekin bypasses the two fly ash silos and is directly sent by pressure to the STAR fly ash silo.

• The resulting product fly ash from STAR is then directed to McMeekin’s two fly
ash silos where it is dry unloaded and sold to cement companies. McMeekin
worked wit h the company operating the STAR so that they could use the silos for storage and unloading of the product fly ash. Once the dry fly ash enters the STAR silo, McMeekin is not responsible for any of the product dry fly ash.

• When the STAR is down, McMeekin sends the dry fly ash to the nearby Wateree power station, which operates a carbon burnout (CBO) facility for disposal. If the fly ash does not meet the LOI criteria for the STAR or CBO facility at Wateree

, the fly ash is moisture conditioned and sent to the un lined , onsite landfill.
Wateree’s CBO can run on 8.5 or greater LOI with the ideal LOI of 9 to achieve maximum finished product. The STAR unit can operate with LOI between 6

- 20
with the ideal LOI of 8

- 10 to achieve maximum finished product.

• McMeekin has experienced minimal maintenance issues (e.g., plugging and pressure seals) with the system. Weekly preventative maintenance on the dry pressure fly ash system include s inspecting valves, piping, and other equipment

.

• McMeekin determined through opera ting the dry pressure system that a dry vacuum system would be ideal for the plant; however, there is no justification for altering the system at this point.

Surface Impoundments and Landfills

• During the Saluda Dam Rem e diation project, the plant determi ned that the ash pond, which began operating in 1987, would need to be dewatered, dredged, and
closed. The ash pond previously received CPR, LVW, fly ash sluice, and bottom ash sluice. After completion of the dam, the plant used the closed ash pond as an

e xtension to the existing onsite landfill. The planned area (the closed ash pond footprint) for the landfill extension has a clay liner.

• The contractors building the dam were also responsible for closing the ponds to use that area as a stock pile and mixing area required for dam construction. The contractor developed a closure plan for the ash pond. Dewatering the ash pond
took several mont hs. The contractor had issues with keeping the pond dewatered; therefore, a multi

- step process was used to complete the project. The contractorPage 9

dewatered approximately 10 feet of the pond and dredged/landfilled the material. Afterwards, the contractor dewa tered and dredged another 10 feet of the pond until the project was complete. Afterwards, they backfilled the ponds and poured a working road

- based surface. Ash sluicing to the ash ponds ceased in fall of 2002. Dewatering and closure began in October 2002 and was physically completed by June 2003 for the two primary ash settling cells. A third “polishing pond” cell was dewatered in December 2003 and closed between December 2003 and September 2005. The ponds were administratively certified as closed in
Novem ber 2005. Approximately 800,000 cubic yards of ash were removed from the three pond cells and placed in the onsite landfill.

• Currently, there are four ponds onsite. Two new ponds were built prior to the ash pond closing in 2000

- 2003 as part of the site pl an for the Saluda Dam Remediation project. These two ponds are the CPR pond and the LVW pond (both waste streams were previously sent to the ash pond ). These ponds operate in
series. The LVW acts more as a polishing pond and there is pH control
downstream of the CPR pond. The CPR pond volume is 314,000 cubic feet. The LVW pond volume is 183,000 cubic feet. While the facility does not have flow monitoring equipment at the CPR and LVW Ponds, the flows to/from these ponds (approximately 200,000 gpd) were previ ously estimated and submitted to EPA for
the ICR

.

• The other two ponds are a lined, ash landfill runoff pond which discharges through O utfall 002 to the Saluda River , and the quarry reclamation pond which discharge s through O utfall 005 to the Saluda River

.

• The onsite, un lined landfill stores fly ash and bottom ash from the plant.Page 10

Table 2

. Site Visit Attendees

Name Organization (Representing) Telephone E

- mail

Tom Effinger SCANA 803

- 217

- 9367 teffinger@scana.com

Mike Summer SCE&G 803

- 217

- 9155 msummer@scana.com

Katrina Franklin SCE&G 803

- 217

- 4147 ksfranklin@scana.com

Ray Ammarell SCE&G 803

- 217

- 7322 rammarell@scana.com

Mark Ferguso n SCANA 803

- 217

- 8103 mferguso n1@scana.com

John Durkee E 2 S 843

- 214

- 0663 e2sciences@bellsouth.net

Donna Hill Southern Company 205

- 257

- 5234 dbhill@southernco.com

Richard Salley SCE&G 803

- 217

- 4121 rsalley@scana.com

Marty Chapman SCE&G 803

- 217

- 4122 mchapman@scana.com

Ron Jordan EPA 202

- 566

- 1003 jordan.ronald@epa.gov

Jezebele Alicea EPA 202

- 566

- 1755 alicea.jezebele@epa.gov

Daisy Wang ERG 703

- 633

- 1692 daisy.wang@erg.com

Elizabeth Sabol ERG 610

- 344

- 0829 elizabeth.sabol@erg.com