Draft Notes from Site Visit at South Carolina Electric & Gas Co mpany ’s Wateree Station on January 24, 2013

EPA conducted a site visit at South Carolina Electric & Gas Co mpany ’s ( SC E & G ) Wateree Station (Wateree) located in Eastover, SC on January 24, 2013 to learn about the operations at the plant, specifically the bottom ash handling retrof it from wet sluicing to using a remote submerged flight conveyor (SFC). 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 remote SFC that the SCE&G personnel gave during the site visits are provided as Attachment 1 to these notes.

Plant Overview

• Wateree operates two identical coal

- fired generating units. Units 1 and 2, which began operation in 1970 and 1971, respectively. Each unit has a gross generating capacity of 372 megawatts (MW). Both generating units are categorized as base load units. Table 1 below contains some general information for the two generating units.

Table 1. Plant Summary

SE Unit Installation

Date Gross Capacity (MW) Particulate Control NOx Control

1 1970 372 Reverse Gas Baghouse SCR, Low NOx burner

2 1971 372 Reverse Gas Baghouse SCR, Low NOx burner

• The Wateree plant is loca ted on 1

, 300 acres of land adjacent to the Wateree River. Wateree employs approximately 100 employees on site. The plant draws raw

intake water from the Wateree River. [QUESTION FOR WATEREE: P lease confirm the number of people employed on site?]

• At full load, Wateree burns 6,000 tons of coal per day. The ash content of the coal

is approximately 10 percent

. [QUEST ION FOR WATEREE: Please provide the type of coal burned and the suppliers of the coal .] Wateree stated th at the fly ash

and bottom ash split is approximately 90/10, respectively, which is roughly 22.5

tons per hour (tph) of fly ash and 2.5 tph of bottom as h. In total, Wateree generates 150,000 tons of ash per year.

• Wateree initiated the retrofit of the wet sluicing bottom ash handling system on

both units in 201 1

. Wateree install ed two remote SFCs , which dewater the bottom

ash sluice and re cycle the overflow back to the boiler to be reused as quench

water ( in the bottom of the boiler ) and sluice water. Wateree completed t he

retrofit on both units in October 2012

.

• Wateree operates reverse gas bag houses to control fly ash and particulate

emissions fro m the plant and pneumatically conveys the collected fly ash to two

silos (one specific to each unit)

. Wateree has the capability to handle the collectedPage 2

fly ash both wet and dry , but aims to transition to completely dry fly ash handling at the projected cl ose of the primary ash settling pond (Ash Pond 1) in 2015.

• Currently, Wateree operates two ash pond s (Ash Pond 1 and Ash Pond 2) , in series, that store fly ash and bottom ash from the wet sluicing operations. Ash

Pond 1 is where the majority of the settling occurs, while Ash Pond 2 acts as a polishing pond prior to discharge. Both the fly ash and bottom ash handling systems have the ability to direct wet sluice to the ash ponds , even after the

bottom ash conversion to th e remote SFC

. Based on some groundwater monitoring results, Wateree is currently planning to close Ash Pond 1 by 2015. As part of the closure, Wateree’s goal is to eliminate the use of the fly ash wet sluicing system and operate the remote SFCs as a comple te recycle system.

• Wateree installed selective catalytic reduction (SCR) systems on both units to control nitrogen oxide (NOx) emissions from the plant. Additionally, the boilers are operated with low

- NOx burners. [QUESTION FOR WATEREE: Can you

confirm th e NOx controls on both units and provide their installation dates? Do these systems operate year round?]

• Wateree operates one wet flue gas desulfurization ( FGD ) system which services both units. This system is a limestone forced oxidation system that ach ieves a 90% sulfur dioxide (SO 2 ) removal efficiency. The plant uses i ntak e water from

the Wateree River a s FGD reagent preparation water, absorber make

- up water,
and mist eliminator wash water.

• Wateree sells its fly ash and bottom ash to cement and concrete pipe manufacturers. The plant also sells a mix of fly ash and bottom ash that is dredged

from Ash Pond 1, fly ash product from the carbon burnout (CBO) process, and

dewatered bottom ash from the remote SFC. Wateree sto res any fly ash and

bottom ash that cannot be sold in a lined, onsite landfill.

Bottom Ash Handling

• In 2012, Wateree converted their bottom ash handling system to a remote SFC designe d by United Conveyor Corp oration (UCC). Wateree started planning the bottom ash handling system conversion in 2010 for both units. Construction for the remote SFC systems started in 2011, simultaneously for both units, in a n area of the plant that was not occupied by any equipment or buildings at the time. [ QUESTION FOR WAT EREE: Please provide the key points of the retrofit timeline, starting from when the project went out to bid, to end of construction

. ]

The remote SFC retrofits were completed by the end of October 2012. The units were fully operational at that time, but th e plant continued to work through minor start up issues through December 2012 . The startup issues included working on flow regulation, and sorting out the controls, sensors , pumps and valves. In total,

t he bottom ash conversion took approximately 2.5 years from inception to completion.Page 3

• Prior to the conversion, Wateree wet sluiced bottom ash to the ash pond s. From the ash ponds, Wateree adjusts the p H of the water prior to discharge to the

Wateree River via Outfall 03A.

• Watere e started looking into bottom ash handling retrofit options after determining that wet sluicing bottom ash to Ash Pond 1 was not a sustainable

, long term solution. Wateree stated that they were trying to anticipate what could

result from the revisions to t he Steam Electric ELGs. Furthermore, Wateree aimed

to close Ash Pond 1 by 2015 to improve groundwater quality.

• As stated previously , t he bottom ash technology evaluation began in 2010.

Wateree evaluated the following systems for the conversion:

o Mechanical drag system (MDS);

o Dr y drag conveyer system /vibratory conveyor system;

o Pneumatic handling systems (vacuum/pressure);

o Complete recycle system with dewatering bins; and

o Remote SFC (operated in complete recycle).

• Wateree did not install the MDS, dry drag conveyor system, or the vibratory

conveyor system because these dry ash handling systems require more space in

the boiler basement than Wateree has available . Additionally, Wateree d oes not
have a direct path out of the boiler room required for th ese types of conveyor systems . Accommodating t hese systems would have required boiler a nd hopper modifications, and relocation of equipment and piping beneath the boiler such as the boiler feed booster pump and the coal mill process piping. Additionally, t here was not enough vertical space below the boilers, so installing any of these options would have required excavation.

• Wa teree did not install any pneumatic bottom ash handling systems due to vertical space underneat h the boiler and bad experiences with the systems at the SCE&G

McMeekin Station . Wateree noted the following issues with a pneumatic bottom ash handling system based on its experience with the McMeekin Station :

o Total length of piping required for the syste m and likelihood that it would plug (characteristics of bottom ash) ;

o N ew air compressor required to move ash;

o Modification required to the bottom of the furnace to replace the wet boiler seal;

o Limited space for any e xcavation underneath the boiler; and

o Employee safety concerns working with the system

.

• Wateree personnel explained that after the initial evaluation, t he remote SFC and

dew atering bin complete recycle systems had equal benefits. Wateree evaluated the following items to select the system for the conversion :

o Confidence in the technology;

o Capital installation costs;

o Life cycle costs;

o Equipment/footprint/layout required for the system;Page 4

o Industry and SCE&G experience; and

o Schedule for installation.

• Wateree ultim ately selected the remote SFC system because it was determined to

be more cost effective (on paper, not based on direct numbers because this is the first system of its kind)

, the foot print of the remote SFC wa s more flexible

, and

the installation schedule matched their needs

. Wateree determined that the cost of the substantial foundations required for the dewatering and settling bins were too high. Based on available data about the system , Wateree determined that the remote SFC was a more robust system. A dditionally, Wateree stated tha t because

the remote SFC is at ground level versus the taller dewatering bin set up, the equipment is more accessible and O&M of the remote SFC system is more convenient.

• Wateree installed two remote SFC systems to handle the bottom ash from both

units. T he bottom ash handling system retrofit was completed within the planned

outages in October 2012 . The majority of the construction (which lasted approximately 18 months) was completed while the units were still online. The two systems cost the plant approx imately $22.5 million

. [QUESTION FOR WATEREE: How many weeks was the planned outage ? How long did the work on the bottom ash system take during the outage? What was the overall cost of the retrofit? Can you provide a rough breakdown of cost, including capital cost, O&M, end of life costs?]

• Both remote SFC s are located behind the U nit 2 fly ash baghouse . Each remote SFC was designed large enough to serve as a combined dewatering tank, settling tank and surge tank for the total volume of bottom ash sluice from both units

. The

front of the remote SFC (i.e. the ramp) performs the separating and dewatering

, and the middle and rear of the remote SFC acts as a set tling tank

.

• Although there are two remote SFCs, under normal operating conditions

, Wateree

directs the bottom ash sluice from both units (sequentially) to one remote SFC at a
time , while the other remote SFC acts as a surge (overflow) tank. The plant

alternates between which remote SFC receives bottom ash sluice and which

remote SFC act s as the surge tank every other week so that solids accumulating in

the remote SFC receiving the overflow can be removed. Wateree stated that UCC designed the system to have redundancies (i.e., each individual remote SFC has the capacity to service bottom ash sluice from both units without overflowing to

the other remote SFC ) . In order to operate one remote SFC alone ( i.e., without the other remote SFC as a surge tank) , W ateree staff would need to change some of the operating conditions of the remote SFC for successful bottom ash removal

. [QUESTION FOR WATEREE: What type of operation/controls would change to operate one remote SFC system to dewater all bottom ash from both units if one remote SFC required maintenance?] As a backup, each remote SFC has an emergency flow line located near the front of the SFC that directs water to the remote SFC sump

. The remote SFC sump is an area where emergency overflowPage 5

and water from the bottom ash pile are directed. This water is immediately recycled back into the remote SFCs using slurry pumps.

• Wateree did not make any changes to the bottom of the boiler /hoppers, clinker grinders, or hydroveyor for the retrofit. Wateree installed additional piping and a “Y” joint , approximately 100 feet away from the bottom of the boiler . The forks of the “Y” represent the split in the piping where the plant can direct the bottom

ash sluice to Ash Pond 1 or the remote SFCs

. Additional pi ping around the boiler was installed to return overflow water from the remote SFCs to the hopper ( i.e., makeup quench water). Wateree also altered the bottom ash sluice piping to bring the recycled overflow water from the remote SFCs back to the hydroveyor (the vacuum supplying the power to wet sluice the bottom ash).

• Bottom a sh falls from the boiler into the hopper where it is quenched in water

. The source o f the quench water is primarily overflow recycle from the remote

SFC ; however, Wateree uses raw i ntake water as makeup water for bottom ash handling when necessary (i.e., losses due to evaporation)

.

• Wateree holds the b ottom ash in the hopper s until the o perator s determine it is time to convey bottom ash to the remote SFCs

. The plant usually sluices bottom

ash from each unit on e time during first and second shift ( totaling two times per day for each unit). Wet sluicing the bottom ash takes approximately twenty
minutes f o r each unit. From the bottom ash hopper

, the bottom ash sluice is conveyed

, by hydroveyors

, to the remote SFC system s or Ash Pond 1 . The bottom ash sluice is conveyed approximately 400 feet to 500 feet from the unit to the

remote SFC. Any overflow from the hoppers is directed to an overflow tank prior to being transferred directly to the remote SFC s through different piping than the

bottom ash sluice

.

• The sluice pipes transport the bottom ash sluice to the remote SFC, dropping it directly over the center of the open remote SFC

, and the bottom ash is discharge d over a splash plate. T he splash plate prevent s bottom ash solids from accumulating directl y below the inlet to the remote SFC and evenly distributes the

bottom ash in the remote SFC. As the bottom ash settles, the drag chain collects it

from the bottom of the tank and drag s the bottom ash from th e rear of the system

to the front and up the ramp of the remote SFC. The drag chain consists of two long parallel chains that run the length of the remote SFC. The chains are connected with conveyor blades that run horizontally which are the mechanisms that grab the settled bottom ash and move it up the incline.

• At the front of the remote SFC, the conveyor moves bottom a sh out of the water and up the incline, wh ich dewaters the bottom ash

. The drag chain is operated on a timer, determined during system testing, for optimal bottom ash removal. At the top of the incline, the dewatered bottom ash falls over the edge and in to a concrete
bunker

. The moisture content of the dewatered bottom ash o n the drag chain is approximately 23

- 25 percent

, but the ash continues to dewater to approximately

20 percent moisture as it sits in the concrete bunker

. The water from thisPage 6

additional dewatering is collected in the remote SFC sump and then sent back to
th e remote SFC.

• Wateree personnel stated that they are not concerned about residual solids in the sump because slurry pumps send any water collected back into the remote SFC system for dewatering

. UCC stated that removing solid s from the sumps should not be necessary; therefore, Wateree is not planning any solids removal at this

time. Trucks come to retrieve the bottom ash out of the concrete bunkers periodically. Wateree sells the b ottom ash to concrete and block pipe fabricatio n companies or store s it in the onsite landfill , located approximately one mile from the remote SFC systems

. In the last month , Wateree sold a lmost 100 percent of its

bottom ash. [ QUESTION FOR WATEREE: How frequently do trucks transport bottom ash from the SFC bunkers to the landfill/market?]

• The remote SFC dewatering the bottom ash sluice is receiving bottom ash sluice periodically, makeup water (raw

- intake water) as necessary , water from the remote SFC sumps, hydroveyor water (constantly running), and hopper overflow water (quench water)

. [ QUESTION FOR WATEREE: Why do you need to send makeup water to the remote SFC?] As the remote SFC fills with water, the solids

settle to the bottom and the overflow flows over weirs at the rear of the SFC . The

overflow is directed to the main compartment of the second remote SFC acting as the surge tank

. [ QUESTION FOR WATEREE: How high up are the weirs? What is the capacity of the remote SFC?] Water from the overflow remote SFC is

returned to the boilers constantly by low pressure pumps to supply the hydroveyor with water and keep the water seal on the bottom of the boilers intact

.

• The plant has kept the option of sending the bottom ash sluice to Ash Pond 1 if

needed. The operator controls w hich pipeline the sluice travels down by opening and closing valves at the “Y” junction point

. During the first few months of

remote SFC operation

, Wateree sent some bottom ash sluice to the ash pond s due

to startup issues. M oving forward, Wateree does not plan to send any bottom ash

sluice to Ash Pond 1 , and plans to close Ash Pon d 1 by 2015

. Wateree stated that

the bottom ash sluice f low from the unit to the remote SFC is similar to the sluice

amount previously sent to the pond. Wateree estimates that they are returning approximately 6 MGD of sluice water back to the system compared to discharging it to Ash Pond 1

.

• The new piping for the system is ceramic, fiber glass pipe. This type of pipe is

corros ion resistant

. SCE&G plants have had good experiences with this type of piping for sluicing systems

. The length of pipe from where the new system ties in to the old sluice pipes and the return from the remote SFCs to boiler is all new piping . Wateree insta lled metal piping to transfer makeup water to the remote

SFC system s and boiler

.

• The remote SFC systems are open top tanks. Wateree stated that rainfall does not alter the water balance of the system unless there is a n uncharacteristically highPage 7

rainfall

. [ QUESTION FOR WATEREE: What type of action would be required to recover the system from this type of event ?]

• Wateree stated that the drag chain in the system should last approximately 3 to 5 years prior to requiring replacem ent. Specific plates within the chain cannot be replaced because the chains can stretch and become uneven, making the replacement of a single pla t e difficult. Wateree also stated that they complete tests on the equipment to replace these chains prior to breaking, as preventative

main tenance. After the drag chain, the pumps seals will likely need replacing. The plant stated that the a nnual operati on and maintenance cost ranges from approximately $800,000 to $1.5 million. [ QUESTION FOR WATEREE: At what frequency are replacement pumps seals expected ?]

• Wateree does not monitor the concentration of total suspended solids ( TSS ) recycled from the remote SFC s to the boiler

. UCC complete d some testing on TSS concentrations between operating both remote SFCs compared to operating just one w ithout an overflow tank. [ QUESTION FOR WATEREE: Please provide the TSS levels between the two operating scenarios .] Wateree also stated that they

do not monitor the pH of the recycle stream , and that UCC did not recommend any chemical addition to the recycle stream

.

Fly Ash Handling

• Wateree collects fly ash using fabric filter baghouses

. [ QUESTION FOR

WATEREE: Did the plant previously operate electrostatic precipitators to collect ash? If yes, when did you convert to the baghouses?]

• Wateree can convey fly ash using a wet sluicing system or a wet vacuum pneumatic system. Wet fly ash is sluiced directly to Ash Pond 1

. Dry fly ash from Unit 1 is conveyed to Silo 1. Dry fly ash from Unit 2 is conveyed to Silo 2. Each

silo ha s a capacity o f 1

, 000 tons.

• From Silo 1, the dry fly ash can be pneumaticall y conveyed to the onsite carbon

burnout ( CBO ) system

. The CBO system is a self

- sustained fluid bed boiler , and

it re

- burns the fly ash to achieve a lower loss on ignition (LOI)

. Wateree sends fly

ash to the CBO system with 9 percent LOI

, and the CB O system produces a 1.5
percent LOI product. The plant stores the fly ash product in a storage dome onsite.

If the fly ash feed does not meet the require d 9 percent LOI, then Wateree either supplements the feed with fly ash from outside sources ( e.g., McMeekin) , or moisture conditions the fly ash for disposal in the onsite landfill.

• When Wateree cannot send fly ash to the CBO system

, the plant moisture conditions the fly ash to 20 percent u sing pug mill mixers and transports the fly ash via trucks to the onsite landfill. Only Silo 1 has the capability to send ash to

the CBO system and moisture condition the ash for unloading into trucks.Page 8

• From Silo 2, Wateree can pneumatically convey the dr y fly ash to Silo 1, or wet

sluice the ash to Ash Pond 1

. Silo 2 does not have the ability to send fly ash to the CBO system or unload the fly ash onto trucks

.

• Currently the priority for handling fly ash at the Wateree plant is to re

- burn the fly

ash at the CBO system and market the ash , store it in the onsite landfill, and as a last resort, wet sluice the fly ash to Ash Pond 1

.

• Wateree originally designed t he fly ash handling system to be a dual wet and dry

system

, but the system does not have any redun dancies built in. Because of this

, Wateree need s to wet sluice their f ly ash to the ash pond s if the dry handling system is down for maintenance

. Wateree is working on solutions to handle their fly ash completely dry by the time the y close the Ash Pond 1 i n 2015

.

Flue G as Desulfurization System

• Wateree operates one wet FGD system which services both units. This system is a

limestone forced oxidation system that achieves 90 percent removal of sulfur

dioxide. The plant uses i ntake water from the Wateree River for the FGD reagent preparation water, absorber make

- up water, and mist eliminator wash water.

• Wateree maintains their chlorides concentration in the scrubber at 2 ,000 to 3,000

ppm . Wateree’s design chlorides level is 1 5,000 ppm

. Plant staff stated that this

low chlorides level is due to the quality of their coal, and not due to any special effort on the plant’s part to keep chloride level s low

.

• The plant blows down from the FGD scrubber twice a day. [ QUESTION FOR

WATE REE: What is the flow rate of the scrubber blowdown ?] The blowdown is sent to primary hydrocyclones . T he overflow from the primary hydrocyclones is

transferred back to the FGD scrubber. The underflow from the primary hydrocyclones is sent to the secondary hydrocyclone s

.

• Overflow from the secondary hydrocyclone s (i.e., FGD scrubber purge) is sent to the FGD ponds

. The underflow from the hydrocyclones is sent to Wateree’s dewatering system (vacuum drum filters). [QUESTION FOR WATEREE: Where

does the filtrat e from the vacuum drum filters go?] Wateree stores the dewatered

g y ps um in the onsite landfill.

• The FGD ponds consist of two concrete fore bays operated in parallel

. FGD scrubber purge is discharged into one forebay at a time.

. While one forebay is filling , the other is being dredged and the solids are sent to the onsite landfill. The

two forebays overflow into a combined pond, and then into a polishing pond. From the polishing pond, the treated FGD water discharges into the back end of

Ash Pond 1 (i.e., ne ar the overflow weir) , prior to overflowing into Ash Pond 2.

The FGD wastewater is ultimately discharged to the Wateree River after pH adjustment in Ash Pond 2

. There is a belt press at the FGD ponds to aid in solids

removal.Page 9

• Wateree is currently in the process of installing further treatment for the FGD scrubber purge. As part of the addition al treatment

, Wateree is considering adding equalization tanks (immediately after the hydrocyclones) and a Lamella clarifier with polymer addition prior to send ing t he FGD wastewater to the FGD ponds.

Wateree w ould also add a filter press for solids remov al. Wateree w ould either landfill or potentially sell the solids from the filter press. The filtrate w ould likely be recycled back to the FGD scrubber.

• Wateree is c onsidering this addition because the FGD treatment ponds are filling up with solids , which are difficult to dewater naturally.

Landfills/Ponds

• Wateree currently operates one unlined ash pond (Ash Pond 1) and a polishing pond (Ash Pond 2) in series. Ash Pond 1 receives bottom ash sluice (when the system is not achieving complete recycle) , fly ash sluice (when not handling dry)

, landfill leachate , low volume wastes ( LVW ), coal pile runoff (CPR)

, general runoff, filter backwash, ion exchange wastewater, and boiler leakage

. These

wastewaters enter Ash Pond 1 at the front end of the pond

. Ash Pond 1 also

receives treated FGD wastewater, which enters the ash pond near the overflow

weir in the pond

. Ash Pond 1 is approximately 80 acres and is currently 80% full. Ash Pond 1 drains into the Ash Pond 2 (polishing pond) prior to discharge.

• Wateree intends to close Ash Pond 1 by 2015. Since the installation of the remote SFC, Wateree is confident that they should never need to send bottom ash sluice

to Ash Pond 1 again . Wateree still wet sluices fly ash to Ash Pond 1 when the dry fly ash handling system is down for maintenance. For the other wastewaters,

Wateree installed a lined pond within the existing ash pond, designated as Pond 1.

Pond 1 will be operated as a wastewater pond and will receive landfill leachate, CPR, LVW, treated FGD wastewater , etc. , prior to draining into Ash Pond 2

. Wateree adds chemicals to Ash Pond 2 to ad j ust the pH prior to discharge to

Wateree River

. [NOTE TO WATEREE: What chemicals do you add to adjust the pH? Do you currently have any plans to close or replace Ash Pond 2? ]

• Ash Pond 1 is currently being excavated i n two areas

. The plant is excavating ash

near the inlet of the pond, where the larger particles of ash have settled, and is moving the ash to the landfill. In addition, c ompanies who want to purchase the mixed bottom and fly ash solids are excavating further out in the ash pond, where the finer particles have settled out (more marketable combined ash)

. As part of the

Ash Pond 1 closure and installation of Pond 1, Wateree first set s the dredged

solids on the side of the pond to dewater prior to trucking them away

. Wateree plans to finish dredging Ash Pon d 1 and moving the solids offsite by 2020.

• Wateree personnel stated that they are voluntarily closing Ash Pond 1, based on groundwater monitoring results, as an effort to mitigate groundwater impacts.

Wateree stated that Ash Pond 1 has not had any impacts on surface water.Page 10

• Wateree’s began operating its onsite l andfill 4 years ago . The landfill is designed

for a 30

- 35 year life. The landfill is approximately 180 acres and stores boiler slag, bottom ash, fly ash, and calcium sulfate (gypsum ). The landfill is lined and

the leachate collected is transferred to Ash Pond 1 (which will ultimately be transferred to Pond 1)

.Page 11

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

Jack Robinson SCE&G 803

- 217

- 6324 jrobinson @scana.com

Jim Landreth SCE&G 803

- 217

- 7224 jlandreth @scana.com

Mark Ferguson SCANA 803

- 217

- 8103 mferguson1@scana.com

John Durkee E 2 S 843

- 214

- 0663 e2sciences@bellsouth.net

Donna Hill Southern Company 205

- 257

- 5234 dbhill@southernco.com

April Pokelly SCE&G 803

- 217

- 4020 apokelly@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