From: "Langley, Shannon" <Shannon.Langley@pgnmail.com> 

 

 To: Josh Hall/DC/USEPA/US@EPA 

 

 Cc: "Moorhead, Laurie" <Laurie.Moorhead@pgnmail.com>, "Bryson, Robin R." <robin.bryson@pgnmail.com>

 

 Date: 01/18/2010 10:00 AM 

 

 Subject: RE: Asheville Power Station- EPA follow-up 

 

Josh,

I asked the staff of the Asheville plant to review the plant description

you sent to us. Below is the description of the Asheville plant and

it's FGD wastewater treatment system. Let me know if you have any

questions.

Shannon

Progress Energy -- Asheville Plant

The Asheville plant operates two coal=fired units, with a combined

capacity of 386 MW. (Note that for sake of completeness, Asheville

Plant has 2 combustion turbines that burn either natural gas or No.2

fuel oil for fuel). SCRs are operated on both coal- generating units

for NOx control.

The plant has scheduled routine maintenance outages in early spring and

fall 2010 (currently April and September).

There are 2 limestone forced oxidation FGD systems, each receiving the

flue gas from a generating unit. No additives are used in the absorbers.

Solids are removed from FGD blowdown using centrifugation prior to

sending the purge to treatment.

The treatment for the FGD wastewater is chemical precipitation, followed

by a constructed wetland (CWTS). The FGD wastewater treatment system

operates continuously. Typical flow through FGD WWT is 60 to 65 gal/min

although the system is designed to handle 73 gal/min maximum flow.

The treatment system is operated to target mercury removal. The NPDES

permit limit for mercury at the ash pond outfall (after comingling with

fly ash and bottom ash wastewater in the ash pond) is 0.63 ug/L.

For purposes of process control, the following parameters are monitored

throughout the treatment process (Table 1):

At the FGD blowdown tank: chlorides, Hg, Se, and alkalinity At the

clarifier: Hg, Se At the EQ basin following dilution with river water:

chlorides, Hg and Se

Chemical precipitation

FGD purge à mixing tank where pH is adjusted; metclear is added for Hg

precipitation along with a polymer (proprietary name and formula) to

enhance suspended solid settling and assist with Hg attachment and

precipitation.

Clarifier: settling occurs and clear water flows to river dilution tank

(4:1) to lower chlorides and temperatures. Sludge from bottom of

clarifier is pumped to sludge tank and on to filter press.

River dilution tank, where river water is added to dilute chlorides and

assist with lowering temperature, flows to equalization basins for

settling and cooling prior to flowing to wetlands.

CWTS

The CWTS has a residence time of several days. It discharges to the ash

pond, where the FGD wastewater commingles with bottom ash sluice and fly

ash sluice prior to discharge to the French Broad River.
Table 1. Typical Range and Averages of Process Control Parameters

FGD Blowdown: Hg Range= 650 - 70 ug/l: ave=230 ug/l

 Se Range=4.82 - 1.1 mg/l; ave=2.6

mg/l

 Chlorides Range=14,100 - 88.6 mg/l;

ave=8200 mg/l

 Alkalinity Range= 1800 - 6.7 mg/l;

ave=90 mg/l

Clarifier: Hg Range=176 - 0.2 ug/l; ave=9.35 ug/l

 Se Range=4.7 - 1.5 mg/l; ave=2.5 mg/l

EQ Basin: Hg Range=43.8 - 0.21 ug/l; ave=2.46 ug/l

 Se Range=0.83 - 0.12 mg/l; ave=0.41 mg/l

 Chlorides Range=37,100 - 49.8 mg/l; ave=1744

mg/l

-----Original Message-----

From: Hall.Josh@epamail.epa.gov [mailto:Hall.Josh@epamail.epa.gov]

Sent: Monday, January 04, 2010 4:15 PM

To: Langley, Shannon

Subject: RE: Asheville Power Station- EPA follow-up

Hi Shannon,

No problem, I just returned to the office as well. Thanks for double

checking our info and following up with the plant.

Happy New Year,

Josh

Josh Hall

U. S. Environmental Protection Agency

OW/Office of Science & Technology

Engineering & Analysis Division

Ph: (202) 566-1002

Fax: (202)566-1053

hall.josh@epa.gov

http://www.epa.gov/waterscience/

 From: "Langley, Shannon" <Shannon.Langley@pgnmail.com>

 To: Josh Hall/DC/USEPA/US@EPA

 Date: 12/31/2009 09:54 AM

 Subject: RE: Asheville Power Station- EPA follow-up

Thanks Josh.
I'll verify this info with the staff of the plant and get back to as

soon as I can. I apologize it has taken me so long to get contact you.

I was on vacation from December 10th till yesterday.

Take care.

Shannon

E. Shannon Langley

Senior Environmental Specialist

Environmental Services Section - Carolinas

Progress Energy Carolinas, Inc.

(919) 546-2439 (public)

8-770-2439 (voicenet)

-----Original Message-----

From: Hall.Josh@epamail.epa.gov [mailto:Hall.Josh@epamail.epa.gov]

Sent: Thursday, December 17, 2009 8:57 AM

To: Langley, Shannon

Cc: Jordan.Ronald@epamail.epa.gov; Thomas.Finseth@erg.com; Kurtis Blohm

Subject: Asheville Power Station- EPA follow-up

Shannon,

Below, I've summarized the information we've collected about the

Asheville plant. Would you please confirm the information included is

correct? I've included a few questions regarding certain operations at

Asheville, that are embedded in the text.

If any specific information you provide is considered confidential

business information (CBI) please let us know which items those are so

we can handle it accordingly.

Thanks,

Josh Hall

U. S. Environmental Protection Agency

OW/Office of Science & Technology

Engineering & Analysis Division

Ph: (202) 566-1002

Fax: (202)566-1053

hall.josh@epa.gov

http://www.epa.gov/waterscience/

Progress Energy -- Asheville Plant

The Asheville plant operates two units, with a combined capacity of 400

MW. SCRs are operated on both generating units for NOx control.

The plant has scheduled outages in early spring and fall 2010 (What are

the specific dates for the outages?)

There is one limestone forced oxidation FGD system, which receives the

flue gas from both generating units. No additives are used in the

absorber. How are solids removed from FGD blowdown prior to sending the

purge to treatment (e.g. hydrocyclones)?

The treatment for the FGD wastewater is chemical precipitation, followed

by a constructed wetland (CWTS). The FGD wastewater treatment system

operates continuously. What is the typical flow through FGD WWT?

The treatment system is operated to target mercury removal. The NPDES

permit limit for mercury at the ash pond outfall (after comingling with

fly ash and bottom ash wastewater in the ash pond) is 0.63 ug/L. Prior

to dilution, in the 2nd Equalization tank, what are the typical effluent

concentrations (e.g. range, average, etc) for Hg? Se? Other parameters

that are monitored for?

Chemical precipitation

FGD purge à Equalization tank à Clarifier à 2nd Equalization tank

Metclear and another polymer (what is the other polymer and what is it

used for?) are added to the clarifier. The Metclear is added for
mercury removal. Clarifier underflow is sent to a filter press, and

clarifier overflow is sent to a 2nd Equalization tank. The 2nd

Equalization tank receives plant service water to dilute (3:1 dilution)

chlorides prior to sending the wastewater to the CWTS.

CWTS

The CWTS has a residence time of several days. It discharges to the ash

pond, where the FGD wastewater commingles with bottom ash sluice and fly

ash sluice prior to discharge to the French Broad River.