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Post Proposal Follow‐Up Questions for United Conveyor Corporation

June 9, 2014

EPA proposed revisions to the effluent limitations guidelines and standards (ELGs) for the Steam

Electric Power Generating Point Source Category (40 CFR Part 423) on June 7, 2013 (78 FR 34431). Based

on our conversation with you on January 14, 2014, EPA has some additional questions regarding costs

associated with conversions to dry fly ash and bottom ash handling systems.

Fly Ash  

EPA’s fly ash cost methodology estimates compliance costs associated with converting from a

wet sluicing system to a dry vacuum handling system. The methodology accounts for costs associated

with conveyance, intermediate storage (i.e., silo and pugmill), and the transportation/disposal portions

of the fly ash handling system. The following are the questions EPA has regarding fly ash conversion

costs.

1. Are the following pieces of equipment, and suggested service life, applicable and reasonable for

a dry vacuum fly ash handling system?

 Vacuum blowers (replaced every 2‐3 years);  

 filter collector bags (replaced every 3 years);  

 pressure blowers, pipe fittings, and valve replacement (replaced every 5 years); and

 convey pipe (replaced every 10 years).

2. Please provide capital cost estimates for the specific pieces of equipment listed in Question 1 for

a dry vacuum system with the following fly ash conveying rates:  

 10‐12 tons per hour (tph);

 20‐22 tph;

 30‐35 tph; and

 50 tph.

3. Would you consider the equipment and service life described in Question 1 as “materials and

equipment replaced due to consumption or wear and tear?”

4. Are the following pieces of equipment, and suggested service life, applicable and reasonable for

a wet sluicing fly ash handling system?

 Hydrovactor nozzle replacement (replaced every 3 years);  

 air separator tank (replaced 10 years or longer);  

 pressure blowers, pipe fittings, and valve replacement (replaced every 5 years); and  

 convey pipe (replaced every 10 years or longer).
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5. Please provide capital cost estimates for the specific pieces of equipment listed in Question 4 for

a wet system with the following fly ash conveying rates:  

 10‐12 tph;

 20‐22 tph;

 30‐35 tph; and

 50 tph.

Are these pieces of equipment and service life comparable to the equipment and service life

required for a dry vacuum system?

  

6. If information is available, provide the typical unloading rate and horsepower for dry unloading

equipment from ash silos.

  

7. Can you describe the modifications that might be required (e.g., equipment, associated O&M)

for a dry fly ash handling system to include a “backup water supply and power supply to the

silo” to completely eliminate the use of a backup wet sluicing system? Why might these

modifications be necessary for a plant to eliminate the use of the backup wet sluicing system?

Bottom Ash

EPA’s bottom ash cost methodology estimates compliance costs associated with converting

from a wet sluicing system to a Submerged Flight Conveyor (SFC) or Remote SFC. The methodology

accounts for the system costs and the transportation/disposal of the dewatered bottom ash. The

following are the questions EPA has regarding bottom ash conversion costs.

1. Do you have any capital cost information for building costs associated with a Remote SFC?  

‐ If yes, please provide capital cost estimates, as a function of unit capacity (in megawatts) or

as a percentage of total equipment capital costs?  

‐ If no, can you recommend any vendors to contact to obtain building costs?

2. Can SFC bottom ash handling systems handle bottom ash from cyclone boilers?  

‐ If so, please provide an example plant that operates a SFC to handle bottom ash from a

cyclone boiler or explain why it is feasible to do so.

‐ If not, what systems, excluding wet sluicing, are available to handle bottom ash from

cyclone boilers? Please also provide an explanation as to why SFC systems cannot handle

bottom ash from cyclone boilers.  
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3. Can Remote SFC bottom ash handling systems handle bottom ash from cyclone boilers?  

‐ If so, please explain why it is feasible to do so.

‐ If not, what systems, excluding wet sluicing, are available to handle bottom ash from

cyclone boilers? Please also provide an explanation as to why Remote SFC systems cannot

handle bottom ash from cyclone boilers.