Draft Notes from Site Visit at South Carolina Electric & Gas Company’s McMeekin 

Station on January 25, 2013

EPA conducted a site visit at South Carolina Electric & Gas Company’s (SCE&G) McMeekin

Station (McMeekin) located in Columbia, SC on January 25, 2013 to learn about the operations 

at the plant, specifically the dry combination vacuum/pressure bottom ash handling system.

These notes describe the information collected during 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 gave 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 generating 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 

baghouse

Overfire Air (Dec 2004), Low 

NOx Burners (July 1999)

2 1958 125 Fabric filter 

baghouse

Overfire Air (Dec 2004), Low 

NOx Burners (July 1999)

[QUESTION FOR MCMEEKIN: Please confirm the NOx controls on both units and their 

installation dates. Do these systems operate year round?]

• 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, SCE&G constructed a backup dam as a preventative 

measure in case of a dam failure due to the presence of fault lines in South 

Carolina. As part of the Saluda Dam Remediation project, several 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 systems as part of the Saluda Dam Remediation project because of space 

constraints and operation and maintenance costs associated with the wet sluicing

systems. McMeekin initially converted to a dense phase dry system between 2002 

and 2003. McMeekin then replaced the dense phase dry bottom ash conveying 

system with a dilute phase, vacuum/pressure system in 2008. [QUESTION FOR 

MCMEEKIN: Please confirm that these dates are correct.]
• Specifically, the sluice lines transferring fly and bottom ash sluice from the plant 

to the ash ponds ran along the original dam; therefore, these pipes needed to be 

relocated to continue sluicing to the ash ponds. McMeekin evaluated realigning 

the piping; however, 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 removed the solids from the ash pond 

and it was closed in 2003. [QUESTION FOR MCMEEKIN: Please confirm that 

the ash pond was completely closed in 2003.]

• McMeekin retrofitted both units with completely dry fly ash and bottom ash 

systems in 2002. McMeekin installed 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 bottom ash from both units to one 

bottom ash silo. However, due 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 are 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 onsite. At full 

load, the plant burns 1,800 to 2,000 tons of coal per day. The ash content of the 

coal is approximately 8 to 9 percent. [QUESTION FOR MCMEEKIN: Please

provide the type of coal stored on site and the suppliers of the coal.]

• McMeekin burns oil only during startup operations.

• McMeekin is currently planning to convert the two coal-fired units on site to 100 

percent gas-fired units by modifying the gas burner arrangement on these existing 

burners. The boilers are already designed to co-fire coal and gas. [QUESTION 

FOR MCMEEKIN: What year is the fuel conversion planned?] 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 fly ash to cement and block 

manufacturers. In the event that fly ash is not sold, it is stored in a class 2 (clay 

lined) lined, onsite landfill. Currently, the plant does not sell bottom ash and all of 
it is stored in the onsite landfill. The landfill was initially brought online in 1987. 

After construction of the dam, McMeekin utilized the closed ash pond footprint to 

expand the landfill.

Ash Handling Conversions – Timeline and Background

• McMeekin converted the fly and bottom ash handling systems as part of the 

Saluda Dam Remediation project. McMeekin started evaluating the possibility of 

building the backup 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.

• McMeekin hired a consultant to develop a master site plan for the plant in 1999. 

As part of the site plan, the plant 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 pond was dewatered, the ash was moved to an onsite 

landfill, and the pond was backfilled. Initial dewatering of the pond took 

approximately 2 months, during which time the plant was removing ash and 

continuously pumping the remaining water out of the pond. In addition to the fly 

ash and bottom ash sluice water, the pond also stored discharges from coal pile 

runoff (CPR) and low volume wastes (LVW); therefore, the plant determined 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, McMeekin 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 supplying 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 system, 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 ash 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 not 

install the screw conveyor due to the high estimated installation, operation, 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 
evaluation, 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 underneath 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. The ash systems were being installed at 

this time. As a result of these two construction projects, the plant was offline in 

the fall of 2002 for a 10-12 weeks outage. The maintenance outage extended 

longer than 10-12 weeks to complete construction 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 and a LVW pond closer to the plant in 2000 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. During this outage, the plant started dewatering, dredging, 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 ash at a single time, there were issues 

associated with this system, including 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 pipe 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 completely 

changed out the hoppers underneath the boiler for the dry system. The bottom of 

each boiler was equipped with five refractory lined hoppers. As part of the wet 

hopper removal, the plant excavated a 36” pit to accommodate the equipment 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 

temperature design criteria of 1200°F.

• In 2008, McMeekin removed all the dense phase pressure system equipment that 

transported the bottom ash from directly underneath the five refractory lined 

hoppers to the bottom ash silo; however, the five refractory lined hoppers 

remained intact. The plant then installed the dilute phase combination 

vacuum/pressure system. This retrofit was completed within a scheduled 8-12 

week outage. [QUESTION FOR MCMEEKIN: Please confirm if the scheduled 8-

12 week outage was planned for that length of time because of the conversion 

(i.e., the conversion was the driver for the length of the outage; if the conversion 

was not occurring, the outage would have been shorter).] No additional outage 

time was required for the second bottom ash conversion.

• For the new combination vacuum/pressure bottom ash handling system, the 

bottom ash is collected in the same five refractory lined hoppers located under 

both units installed in 2002. Both units have identical equipment underneath the 

hoppers. “Bomb 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 system. 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 combines prior to the transfer station. The

remainder 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, equipped with a bag filter, the vacuum is exhausted to the 

atmosphere and the bottom ash drops into Nuva Feeders. 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. 

• 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 

horizontally to the bottom ash silo then runs vertically up the bottom ash silo 

approximately 90 feet. 
• Bottom ash from both units is transferred to a 300 ton silo, which the plant

estimates to be approximately 8-10 days worth of bottom ash storage.

[QUESTION FOR MCMEEKIN: What is the moisture content of the bottom ash 

inside the silo?]

• The bottom ash is then moisture conditioned to approximately 19 percent, using a 

pugmill unloader. The moisture conditioned bottom ash is loaded from the silo 

into a dump truck and transferred 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 landfill.

• 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 bottom 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, corrosion resistant piping with lined elbows. [QUESTION FOR 

MCMEEKIN: What type of piping replaced the carbon steel?]. McMeekin 

estimates that the new pipes likely need to be rotated 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 the 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 pull 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 dilute 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. [QUESTION FOR MCMEEKIN: Please confirm that this is the 

reason the plant did not install the vacuum system compared to the 

vacuum/pressure system.]

• McMeekin stopped burning low sulfur coal approximately a year prior to the site 

visit because it was causing plugging issues in the bottom ash handling system. 

[QUESTION FOR MCMEEKIN: Can you confirm why low sulfur coal is more 
prone to clogging?] Since the fuel switch, McMeekin has not had many problems 

with plugging, although occasional plugging still occurs, specifically in the plugprone vertical length of piping prior to the bottom ash silo. 

• According to plant personnel, switching 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 long 

hours of man power for unplugging lines, fixing inflatable seals that became 

problematic because of the temperature of the bottom ash, and “babysitting” the 

system.

• 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 an identical 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 pyrites are more uniform in particle size, a retrofit to 

the combination vacuum/pressure system was not necessary in 2008. Therefore, 

McMeekin operates the original pressure system and transfers the mill rejects and 

pyrites to the bottom ash silo for disposal. McMeekin does have the option of 

sending the mill rejects and pyrites to the fly ash silo if desired.

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, which 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 silos from both units.

• The fly ash silos are both equipped with moisture conditioning unloading 

equipment and completely dry unloading equipment. McMeekin moisture 

conditions the dry fly ash with filtered service water from Lake Murray to 19 

percent moisture to control fugitive dust at the landfill if it cannot be marketed. 
[QUESTION TO MCMEEKIN: Can you confirm the 19 percent moisture for 

moisture conditioned ash?]

• Although McMeekin has two dry fly ash silos, currently, the plant sells 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) of 

the fly ash. The final LOI, after the STAR, is approximately one. 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 with 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

(8-9 LOI), the fly ash is moisture conditioned and sent to the lined, onsite landfill.

[QUESTION TO MCMEEKIN: Can you confirm that the criterion for both the 

STAR and CBO at Wateree is a fly ash LOI of approximately 8-9?]

• 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 includes inspecting valves, piping, and other equipment. 

• McMeekin determined through operating 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 Remediation project, the plant determined 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 

extension 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 for 

the stock pile and mixing area required for dam construction. The contractor 

developed a closure plan for the ash pond. First, the ponds were dewatered and 

the ash was dredged and landfilled. Afterwards, they backfilled the ponds and 

poured a working road based surface. The ash pond closure was completed in 
2003. [QUESTION FOR MCMEEKIN: Please confirm that the ash pond was 

completely closed in 2003.]

• Dewatering the ash pond took several months. The contractor had issues with 

keeping the pond dewatered; therefore, a multi step process was used to complete 

the project. The contractor would dewater approximately 10 feet of the pond and 

dredge/landfill the material. Afterwards, the contractor would dewater and dredge 

another 10 feet of the pond until the project was complete. [QUESTION FOR 

MCMEEKIN: How long did the dewatering and closure process take from start to 

finish? Additionally, what was the cost to close the pond? How much fly ash and 

bottom ash were removed from the pond and stored in the landfill as part of the 

closure process?] 

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

pond closing in 2000 as part of the site plan for the Saluda Dam Remediation 

project. These two ponds are the CPR pond and the LVW pond (both waste

streams previously sent to the ash pond). These ponds are operate in series. The 

LVW acts more as a polishing pond and is the downstream pH control of the CPR 

pond. [QUESTION FOR MCMEEKIN: Please provide the volume (in cubic feet) 

of the ponds. Additionally, please provide the flowrate for the influent(s) to and 

the effluent(s) from these ponds.] 

• The other two ponds are a lined, ash landfill runoff pond which discharges 

through outfall 102 to Lake Murray, and the quarry reclamation pond.

[QUESTION TO MCMEEKIN: Can you confirm the outfall number 102?]

• The onsite, lined landfill stores fly ash and bottom ash from the plant. 
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 Fergusan SCANA 803-217-8103 mfergusan1@scana.com

John Durkee E2

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