From: Elizabeth Sabol

To: rong@deltaducon.com

CC: Alicea.Jezebele@epa.gov; Bartram, Deborah; Finseth, Thomas; Ventre, Adam; jordan.ronald@epa.gov

Date: 11/8/2010 2:50 PM

Subject: Ash Handling Data Request

Attachments: Delta Ducon_Ash Handling Attachment_11.10.doc

Ron,

My name is Elizabeth Sabol, from Eastern Research Group, Inc. ERG is a contractor for the U.S. EPA’s Office of Water, and we are 

supporting EPA’s review and revision of effluent guidelines for the steam electric power generation industry. Thank you for your 

assistance during our conference call in December 2009 in discussing the design and cost of ash handling systems. As you may 

recall, EPA was at that time preparing to distribute the Questionnaire for the Steam Electric Power Generating Effluent Guidelines. 

The questionnaire was distributed to the industry in June and the questionnaire is currently being received and reviewed by EPA. 

The questionnaire and other pertinent background information can be found online at: http://www.epa.gov/guide/steam. 

In order to accurately revise the effluent guidelines, EPA is developing a methodology to estimate the costs associated with various 

technology options of interest to EPA. EPA is currently evaluating costs associated with the conversion of wet to dry fly ash handling 

and the conversion/installation of bottom ash handling systems that do not discharge bottom ash sluice water. 

Attached, please find a document that summarizes some background on the cost approach that EPA is developing and a list of 

questions for which we would appreciate your input. EPA is aware that system-level cost data varies among different ash handling 

scenarios in the industry. We encourage you to provide cost data for scenarios that you consider typical in the industry. If you 

would like to discuss any assumptions that must be made to develop cost data for particular systems, please contact me with your 

questions or times when you are available for a call (please find my information below). 

EPA is requesting Clyde Bergemann/Delta Ducon's cost information by early December. We look forward to your answers and 

comments regarding costs associated with fly and bottom ash handling. We would appreciate your feedback and thank you in 

advance for your time. 

Thanks, 

Elizabeth

Elizabeth A. Sabol

Environmental Engineer

Eastern Research Group, Inc.

14555 Avion Parkway, Suite 200

Chantilly, VA 20151

elizabeth.sabol@erg.com

Phone:703-633-1659
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Introduction

EPA is currently developing a methodology to estimate the cost of conversions 

from wet to dry fly ash handling and the installation/conversion of bottom ash handling 

systems with systems that do not discharge sluice water. Below please find a brief 

overview of this methodology and a list of questions/cost requests that will assist EPA is 

further developing this methodology. 

Cost Methodology Background

Fly Ash Conversion

EPA is developing a methodology that will estimate costs associated with the 

conversion from wet to dry fly ash handling at coal-fired power plants. The methodology

will account for costs associated with the conveyance, intermediate storage, and 

transport/disposal portions of the fly ash handling system. This component-level 

approach to the ash handling system mirrors how EPA requested cost information in the 

questionnaire. 

The four dry fly ash handling systems that EPA is evaluating include: 

• Wet vacuum (pneumatic): System retrofit that utilizes the existing wet 

vacuum exhauster to pull vacuum for the dry system;

• Dry Vacuum: System that uses a mechanical exhauster to move air to 

entrain and convey dry fly ash particles (ideal for short distances);

• Pressure: Pressurized system that uses air produced by a positive 

displacement blower to convey ash to a certain destination (ideal for 

longer distances); and

• Combination vacuum/pressure: System that utilizes the vacuum 

equipment underneath the hoppers to transport fly ash by vacuum to a 

transfer station, where it is introduced to positive pressure and 

transported longer distances.

The methodology will evaluate the existing ash handling system, as well as the 

conveyance distance and ash capacity associated with each plant to determine the most 

appropriate dry fly ash handling system to be installed.

Bottom Ash Conversion/Installation

EPA is developing a methodology that will estimate the costs for bottom ash 

handling system conversions and new installations. The bottom ash handling 

methodology will account for costs associated with the conveyance, intermediate storage, 

and transport/disposal portions of the bottom ash handling system. The three bottom ash 

handling systems that EPA is evaluating include:
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• Complete Recycle System: Bottom ash system that utilizes dewatering 

bins and corresponding tanks to recycle all sluice water back to the 

system (Note: this system is a closed complete recycle system and 

does not include the use of ponds);

• Mechanical Drag System: Drag chain system that works on an incline 

to pull bottom ash from the quench water underneath the boiler to an 

intermediate or final storage destination;

• Pneumatic Handling Systems: Dry bottom ash handling system that 

grinds up bottom ash at the bottom of the hopper and transfers it 

pneumatically to an intermediate or final storage destination.

Questions Regarding Fly and Bottom Ash System Operations and Costs

In order to properly develop the methodology to evaluate the installation and 

conversion costs for the industry, EPA would like to request system-level operating and 

cost information from you. Please respond to the following questions below to ensure that 

the cost model reflects appropriate information/costs.

General Fly Ash System Design Characterization

1. Please provide your estimate for the maximum capacity (tons/hour) and maximum 

distance that should be assumed for wet vacuum (pneumatic), dry vacuum, 

pressure, and combination vacuum/pressure systems.

2. When evaluating the conversion of an ash handling system from wet to dry, are 

there any circumstances that specifically require the installation of a pressure fly 

ash handling system (e.g., capacity requirement exceeds maximum capacity of 

vacuum or combination vacuum/pressure systems)?

3. Is there a type of dry ash handling system typically used to retrofit existing power 

plants? If yes, what about that particular system makes it preferable (e.g., ease of 

installation, capital, O&M)?

4. For each dry fly ash system, what is the typical length of outage required for the 

installation (or conversion to) the system? If known, what is the typical outage 

per year associated with scheduled and unscheduled maintenance of each type of 

dry fly ash system conversion? Can the conversion be implemented within normal 

scheduled maintenance outages, or must the maintenance outage be extended (and 

if so, for how long)?

5. Please describe how the design of the fly ash handling system would differ for a 

plant using petroleum coke instead of coal.

6. Please describe the type of fly ash handling equipment used for oil-fired boilers. 

Please describe how the design and operation differ from coal-fired fly ash 

handling equipment.
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Wet Vacuum (Pneumatic) Fly Ash Handling System Characterization

7. Please describe the prevalence of wet vacuum (pneumatic) fly ash handling 

systems in industry. What percent of new installations utilize wet vacuum 

systems? What percent of wet-to-dry conversions installed wet vacuum systems?

8. What equipment can typically be retained when converting from a wet fly ash 

handling (sluicing) to a wet vacuum (pneumatic) system? In addition to a wet 

vacuum exhauster (vs. a mechanical exhauster), what major equipment is required 

for conversion?

9. What equipment is required for conversion from wet vacuum (pneumatic) fly ash 

handling systems to dry vacuum fly ash handling systems?

10. Do wet vacuum (pneumatic) fly ash handling systems generate a waste stream? If 

yes, how much wastewater is typically generated? What is the wastewaters usual 

destination? What percent of fly ash becomes entrained in the water used to create 

the vacuum?

General Bottom Ash System Characterization

11. Please describe the prevalence of pneumatic bottom ash conveyance systems in 

industry. What percent of new installations and wet-to-dry conversions are 

pneumatic systems?

12. Are there certain boilers that are unable to be retrofitted with a pneumatic bottom 

ash conveyance system (e.g., older boilers)?

13. For each dry bottom ash system, what is the typical length of outage required for 

the installation (or conversion to) the system? If known, what is the typical 

outage per year associated with scheduled and unscheduled maintenance of each 

type of dry bottom ash system conversion?

14. Please describe how the design of the bottom ash handling system would differ 

for a plant using petroleum coke instead of coal.

15. Please describe the type of bottom ash handling equipment used for oil-fired 

boilers. Please describe how the design and operation differ from coal-fired 

bottom ash handling equipment.

Complete Recycle Systems

16. For a complete recycle bottom ash handling system, do you include any costs 

associated with water treatment to prevent or eliminate the build up of dissolved 
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solids? Please describe the type of treatment that is used to eliminate the build up 

of dissolved solids.

17. What costs are included in the installation and operation of a complete recycle 

system? What water (make-up, cooling water, re-circ water) and power 

requirements are needed to operate the system? 

Silo Configuration

18. Please describe the process for sizing a silo for intermediate ash storage.

Specifically, is each silo individually designed for a specific plant, or are there 

several standard silo designs selected from based on amount of ash generated?

19. What factors drive the number of silos installed at a facility? Are silos typically 

sized to hold one unit’s ash, or is a silo typically shared among multiple units that 

generate ash with similar characteristics?

20. What materials of construction are typically used for silos and how is the 

appropriate material of construction determined? Provide range of costs for 

typical materials of constructions for a typical silo.

Costs for Fly and Bottom Ash Handling Systems

EPA is seeking system-level cost information for wet to dry fly ash handling 

conversions and bottom ash handling conversions/installations. EPA would like to obtain 

these costs broken out for the conveyance portion of the system (e.g., from the hopper to 

intermediate storage) and the intermediate storage portion of the system (e.g., silo). EPA 

is aware that cost varies greatly depending on boiler configuration, capacity, conveyance 

distance, and number of units. For the purposes of providing cost data, please assume 

average industry operating conditions and no special circumstances (e.g., headroom 

below the boiler). In order for us to properly evaluate the cost data, please provide the list 

of variables and assumptions used during the development.

Fly Ash

Please provide capital and O&M cost curves for fly ash conveyance (please do 

not include silo costs), based on tons per hour (tph) of fly ash, for the following 

conversion types:

• Conversion from wet sluicing to wet vacuum system;

• Conversion from wet sluicing to dry vacuum system;

• Conversion from wet sluicing to pressure system; and

• Conversion from wet sluicing to combination vacuum pressure system.
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Bottom Ash

Please provide capital and O&M cost curves for bottom ash conveyance (please 

do not include silo costs), based on tph of bottom ash, for the following installations or 

conversion types:

• Conversion from wet sluicing to mechanical drag system;

• Conversion from wet sluicing to pneumatic system;

• Conversion from wet sluicing to a dewatering bin system with 

complete recycle (including dewatering bin, surge tank, and settling 

tanks costs);

• Installation costs for mechanical drag systems; and

• Installation costs for pneumatic systems.

Intermediate Storage

Please provide the following data for silos:

• Silo cost curves (capital and O&M) as a function of capacity (please 

provide separate silo capital cost curves for typical materials of 

constructions used). Please assume that the silo has both wet and dry 

loading capabilities.

Please include a detailed list of components included for each system level cost 

curve provided. Also, please provide an explanation of any underlying assumptions made 

while developing the cost curves (i.e., if outage time or maintenance time was factored in 

the price).

Petroleum Coke-Fired Fly Ash and Bottom Ash Costs

Please provide capital and O&M cost curves for fly ash and bottom ash handling 

systems associated with the handling of ash from petroleum coke-fired units, if different 

than coal-fired units. Please provide cost curves with the same details that are included in 

the request above. 

Oil-Fired Fly Ash and Bottom Ash Costs

Please provide capital and O&M cost curves for fly ash and bottom ash handling 

systems associated with the handling of ash from oil-fired units. Please provide cost 

curves with the same details that are included in the request above.