Draft 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, SC 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 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

b aghouse 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 system s 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, 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 systems 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. Mc Meekin initial ly converted to a dense phase dry system between 2002

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

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

MCMEEKIN: Please confirm that these date s 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 pond s . McMeekin evaluated real igning 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 200 3

. [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 capab ilities. McMeekin initially installed a similar dry, dense phase pressure system to pneumatically convey bottom 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 s ystem 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

u nits 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 onsite. 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. [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 bur ner arrangement on these existing

burners. The boiler s are already designed to co

- fire coal and gas. [QUESTION

FOR MCMEEKIN: W hat year is the fuel conversion planned?] Additionally,

McMeekin is scheduled to retire these two units in 2018 when SCE&G owned

n uclear 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 (clay

line d ) lined, onsite landfill. Curr ently, the plant does not sell bottom ash and all ofit 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 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

.

• 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 p ond was dewatered

, the ash was moved to an onsite

landfill

, and the pond was backfilled. Ini tial dewatering of the pond took approximately 2 months , during which time the plant 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, 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, 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 economicevaluation, 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 th e 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 o utside 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 s outage. The maintenance ou tage extended longer tha n 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 c ut 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 s tarted 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, 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 completely 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 removal, the plant excavated a 36” 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 t he 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 sy stem 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/press ure 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 fiv e refractory lined hoppers located under

both units installed in 2002

. Both units have identical eq uipment underneath the hoppers. “ B om b bay door s ” 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 sp ace 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 combin es 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

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, 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.

• The b ottom 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.• B ottom ash from both units is transferred to a 300 ton silo, which the plant

estimate s 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 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 pipi ng

. 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 pressu re 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 s ystem.]

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

visit because it was caus ing plugging issue s in the bottom ash handling system

. [QUESTION FOR MCMEEKIN: Can you confirm why low sulfur coal is moreprone to clogging ?] Since the fuel switch, McMeekin has not had many problems with plugging , although occasional plug ging still occur s , specifically in the plug

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

• According to plant personnel, s witching from wet s luicing 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 di lute 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 problemat ic 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 b ottom 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 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 as h 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 convers ion 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 si los 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 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 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) 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 silo s 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, whic h 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 d ry pressure fly ash system include s 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 Rem e d iation 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 s tock 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 in2003. [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; therefor e, 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? H ow much fly ash and

bottom ash w ere removed from the pond and stored in the landfill as part o f 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. Additional ly, 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 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