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EPA Home > Region 5 > Air > Correspondence


October 11, 1996

Greg Aldrich, Deputy Director
Air Quality Management Division
Wayne County Department of Environment
640 Temple
Suite 700
Detroit, Michigan 48201

Dear Mr. Aldrich:

This letter is in response to Rhonda Ross' letter of August 16, 1995, requesting a
determination of the applicability of the Standards of Performance for New Stationary Sources
(NSPS), pursuant to 40 C.F.R. 60.5, to a "waste-to-energy" conversion project proposed by
the Central Wayne Energy Recovery Limited Partnership (Central Wayne) for the municipal
waste combustor (MWC) facility in Dearborn Heights, Michigan. Ms. Ross also asked for
clarification on how to apply emissions limits in situations where NSPS and non-NSPS
sources share the same stack.

The MWC facility is currently operated by the Central Wayne County Sanitation Authority
(CWCSA) in Dearborn Heights, Michigan. The MWC facility has three combustion units. Unit 1
and Unit 2 were built in 1963, each with 250 tons per day capacity, and Unit 3 was built in 1970
with a 300 tons per day capacity. Unit 3 is not currently operating. CWCSA entered into
partnership with Central Wayne to upgrade the three combustors to waste-to-energy units,
which includes the installation of steam-generation equipment. At issue is whether the project
will be a "modification" as defined under the NSPS for MWCs. If a MWC unit is a modified
unit, it will be subject to NSPS Subpart Eb for MWCs, and not subject to Subpart Cb emission
guidelines for existing MWCs.

Information provided by Central Wayne indicates that the estimated fixed capital cost of the
new components will be more than 50 percent of the original costs of construction and
installation for each unit. Based on this information, the United States Environmental Protection
Agency (USEPA) has determined that each of the MWC units at Central Wayne will become
subject to the NSPS for Municipal Waste Combustors (40 C.F.R. Part 60, Subpart Eb, as
promulgated on December 19, 1995).

This determination is based on the NSPS and emissions guidelines for MWCs, that were
published in the Federal Register on December 19, 1995, and codified at 40 C.F.R. Part 60,
Subparts Eb and Cb, respectively. In the course of our review of the proposed project at the
CWCSA facility, USEPA Region 5 consulted with USEPA's Office of General Counsel, Office
of Air Quality Planning and Standards, and Office of Enforcement and Compliance Assurance.

Subpart Eb was drafted under the authority of Section 129 of the Clean Air Act, and includes a
new definition of "modification" that supersedes the definition of " reconstruction" provided by
Sections 60.14 and 60.15. Language from the new definition reads:

Modification or modified municipal waste combustor unit means a municipal waste
combustor unit to which changes have been made after June 19, 1996 if the cumulative cost of
the changes, over the life of the unit, exceed 50 percent of the original cost of construction and
installation of the unit (not including the cost of any land purchased in connection with such
construction or installation) updated to current costs; or any physical change in the municipal
combustor unit or change in the method of operation of the municipal waste combustor unit
increases the amount of any air pollutant emitted by the unit for which standards have been
established under section 129 or section 111 . . . 40 C.F.R. 60.51b.

The specific definition of modification in Subpart Eb must be used for an MWC unit located
within an MWC plant with an aggregate MWC capacity greater than 35 megagrams per day of
municipal solid waste for which modification or reconstruction is commenced after June 19,
1996. In reviewing the information for the Central Wayne project, the specific definitions under
Subpart Eb should be used for evaluating applicability to all three units at the facility since the
aggregate plant capacity exceeds 35 megagram per day. The specific provisions in an
applicable Subpart take precedence over the provisions found in the General Provisions
because the specific provisions were promulgated to comply with the requirements in Section
129 of the Clean Air Act and, thus, override conflicting provisions in the General Provisions.

Based on information submitted to your office by Central Wayne on August 3, 1995, and
February 29 and August 15, 1996, and additional information submitted by Central Wayne to
USEPA on April 2, April 26, and August 30, 1996, the capital cost of the modifications to each
unit are more than 50 percent of the original cost of each unit, pursuant to the definition used
under Subpart Eb. We have summarized the costs below:

         Initial Cost of
        Construction (Escalated
        to 1996 dollars)
                                 Costs Reported for
                                 Proposed Project
                                 (1996 dollars)

                                                         Cost of Proposed
                                                        Project Compared to
                                                        Initial Cost (1996 dollars)
 Unit 1
                                                        117 Percent
 Unit 2
                                                        117 Percent
 Unit 3
                                                        100 Percent

The initial construction costs for the facility, reported by unit, were escalated to 1996 dollars
using the ENR Building Construction Cost Index (Engineering News Record, March 25, 1996).
These costs do not include capital improvements made since the date of initial construction.
Cost for items that are not allowable in this calculation (such as air pollution control equipment)
are not included.

In its August 30, 1996, letter to Jeff Gahris of Region 5, Central Wayne stated that the new
"waste heat boilers" would not meet the definition of "MWC unit" based upon the October 1,
1990, memorandum from Tom Elter of USEPA's Control Technology and Compliance Section.
USEPA has determined that "waste heat boilers" at CWERLP meet the definition of an MWC
unit under the Clean Air Act Section 129; therefore, they are part of the affected facility. The
October 1, 1990, memorandum from Tom Elter, concerning steam generating units used with
internal combustion engines, is not applicable to MWC units. The definition of MWCs
specifically includes heat recovery components.

The following addresses Ms. Ross's question on how to apply emissions limits in situations
where NSPS and non-NSPS sources share the same stack. We have received information
indicating that the proposed new emissions stack for the Central Wayne project would follow
one air pollution control system, hence there would be one flue serving all three combustor
units. For such a stack serving units that have differing emissions limits in terms of air pollutant
concentrations, it is USEPA's policy and practice to apply the most strict standard to all of the
units. Nevertheless, for Central Wayne, the NSPS standards will apply to each unit, so this is
not an issue.

If you have further questions on this determination, please feel free to contact Jeff Gahris, of my
staff, at (312) 886-6794.



George T. Czerniak, Jr., Chief
Air Enforcement and Compliance Assurance Branch


Dennis Drake, Chief
Air Quality Division
Michigan Department of Environmental Quality

Thomas Barnett, Project Manager
Central Wayne Energy Recovery, L.P.

For further information, contact:
This Information Last Modified On: 09/18/2008 03:58 PM