UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

REGION III

	1650 Arch Street

	Philadelphia, Pennsylvania  19103

DATE:	May 26, 2011

SUBJECT:	Technical Support Document – Commonwealth of Pennsylvania –
Control of Emissions of Particular Matter from the Operation of Outdoor
Wood-fired Boilers

			/s/

FROM:	Rose Quinto, Environmental Engineer

		Office of Air Program Planning

TO:		File

			/s/

THRU: 	Cristina Fernandez, Associate Director

Office of Air Program Planning

A.  BACKGROUND

On July 18, 1997 (62 FR 38652), the Environmental Protection Agency
(EPA) amended the National Ambient Air Quality Standard (NAAQS) for
particular matter (PM) to add a new standard for fine particles, using
fine particulates equal to or less than 2.5 micrometers in diameter
(PM2.5) as the indicator.  EPA set the health-based (primary) and
welfare-based (secondary) PM2.5 annual standard at a level of 15
micrograms per cubic meter (µg/m3) and the 24-hour standard at a level
of 65 µg/m3.  The health-based primary standard is designed to protect
human health from elevated levels of PM2.5, which have been linked to
premature mortality and other health effects.  The secondary standard is
designed to protect against major environmental effects of PM2.5 such as
visibility impairments, soiling, and materials damage.  

On October 17, 2006 (71 FR 61236), EPA revised the primary and secondary
24-hour NAAQS for PM2.5 to 35 µg/m3 from 65 µg/m3.

A significant and growing source of PM2.5 emissions in the Commonwealth
of Pennsylvania is from outdoor wood-fired boilers (OWBs).  OWBs, also
referred to as outdoor wood-fired furnaces, outdoor wood-burning
appliances, or outdoor hydronic heaters, are free-standing fuel burning
devices designed: (1) to burn clean wood or other approved solid fuels;
(2) specifically for outdoor installation or installation in structures
not normally intended for habitation by humans or domestic animals, such
as garages; and (3) to heat building space or water by means of
distribution, typically through pipes, of a fluid heated in the device,
typically water, or a water and antifreeze mixture.  They resemble a
small shed or mini-barn with a short smokestack on top.  OWBs are being
sold to heat homes and buildings; produce domestic hot water; heat
swimming pools or hot tubs; and provide heat to agricultural operations
such as greenhouses and dairies.

A concern associated with certain OWBs is the air pollution they may
produce.  Smoldering fires and short smokestacks may create heavy smoke
to the ground that sometimes causes a neighborhood nuisance or an
adverse impact on public health and the environment.  Smoke from OWBs
which form from incomplete combustion, contain emissions from fine
particle pollution, carbon monoxide, and other organic products, such as
formaldehyde, benzene and aromatic hydrocarbons, all of which can cause
cancer.  When inhaled, fine particles from smoke emissions are carried
deep into the lungs and can impair lung function and aggregate existing
medical conditions such as asthma, lung or heart disease.  Individuals
particularly sensitive to PM2.5 exposure include older adults, people
with lung and heart disease, and children.

Unlike indoor wood stoves that are regulated by EPA, OWBs are not
required to meet a Federal emission standard, and the majority of them
are not equipped with pollution controls.  EPA initiated a voluntary
program that encourages manufacturers of OWBs to improve air quality
through developing and distributing cleaner-burning, more efficient
OWBs.  Through this voluntary effort, OWBs are certified and labeled to
meet EPA emissions performance levels in two phases.  Phase 1 of the
program was in place from January 2007 through October 15, 2008.  To
qualify for Phase 1, manufacturers were required to develop an OWB model
that was 70% cleaner-burning than unqualified models by meeting the EPA
air emission standard of 0.6 pound PM per million British thermal unit
(Btu) heat input as tested by an independent accredited laboratory. 
Phase 1 OWB models are labeled with an orange tag.  Phase 1 Partnership
Agreements ended when Phase 2 Partnership Agreements were initiated on
October 16, 2008.  To qualify for Phase 2, manufacturers must develop an
OWB model that is 90% cleaner-burning than the Phase 1 OWBs and meet the
EPA air emissions standard of 0.32 pound PM per million Btu heat output.
 The Phase 2 OWB models, just like the Phase 1 OWB models are tested by
an independent accredited laboratory.  Phase 2 OWB models are labeled
with a white tag.  Additional information about the EPA voluntary OWB
program is available on EPA’s Web site at   HYPERLINK
"http://www.epa.gov/burnwise"  www.epa.gov/burnwise .  Furthermore, the
Northeast States for Coordinated Air Use Management (NESCAUM), which is
a regional air pollution control organization, comprised of the air
program directors of all the New England states, New York and New
Jersey, in coordination with a number of states and EPA, developed a
model rule for regulating OWBs (also known as outdoor hydronic heaters
(OHHs)).  The model rule was released in January 2007 and is available
at   HYPERLINK "http://www.nescaum.org/topics/outdoor-hydronic-heaters" 
www.nescaum.org/topics/outdoor-hydronic-heaters .  The purpose of the
model rule is to assist state and local agencies in adopting
requirements that will reduce air pollution from OWBs.  The model rule
establishes emission limits and labeling requirements for new OWBs and
contains the following components for both new and existing OWBs: 
setback requirements from property lines, structures, and homes; stack
height requirements; and distributor and buyer notification
requirements.

On October 20, 2010, the Pennsylvania Department of Environmental
Protection (PADEP) submitted a State Implementation Plan (SIP) revision
pertaining to the control of emissions of particular matter (PM) from
the operation of OWBs.  This SIP revision is based on the NESCAUM model
rule.  The emission standard established in this SIP revision is the
Phase 2 emission standard described in the EPA voluntary OWB program.  

B.  STATE SUBMITTAL

The SIP revision adds definitions and terms to Title 25 of the
Pennsylvania Code (25 Pa. Code) Chapter 121.1, relating to definitions,
used in the substantive provisions of this SIP revision.  The SIP
revision also adds a new regulation pertaining to the standards for
contaminants on particulate matter emissions in 25 Pa. Code Chapter 123
(Standards of Contaminants), Section 123.14 – Outdoor Wood-Fired
Boilers.  

The following definitions and terms were added in 25 Pa. Code 121.1:  

Btu – British thermal unit – The amount of thermal energy necessary
to raise the temperature of 1 pound of pure liquid water by 1°
Fahrenheit (F) at the temperature at which water has its greatest
density (39°F).

Clean wood – The term includes the following:  (1) wood that contains
no paint, stains, or other types of coatings; and (2) wood that has not
been treated with preservatives or chemicals, including copper, chromium
arsenate, creosote and pentachlorophenol.

New Phase 2 outdoor wood-fired boiler – A Phase 2 outdoor wood-fired
boiler that is installed on or after October 2, 2010.

Non- Phase 2 outdoor wood-fired boiler – An outdoor wood-fired boiler
that has not been certified or qualified by EPA as meeting a particulate
matter emission limit of 0.32 pounds per million Btu output or lower and
is labeled accordingly.

Outdoor wood-fired boiler – A fuel-burning device that:  (1) is
designed to burn, or is capable of burning, clean wood or other fuels
listed under allowed fuels in this SIP revision; (2) has a rated thermal
output of less than 350,000 Btu per hour; (3) the manufacturer designs
or specifies for outdoor installation or installation in structures not
normally intended for habitation by humans or domestic animals,
including garages and sheds; and (4) heats building space or fluid, or
both, through distribution, typically through pipes, of a fluid heated
in the device, typically water or a mixture of water and antifreeze. 
The fuel-burning device may also be known as an:  outdoor wood-fired
furnace; outdoor wood-burning appliance; and outdoor hydronic heater.

Phase 2 outdoor wood-fired boiler – An outdoor wood-fired boiler that
has been certified or qualified by EPA as meeting a particular matter
emission limit of 0.32 pounds per million Btu output or lower and is
labeled accordingly.

Summary of the SIP Revision

The SIP revision adds a new regulation in 25 Pa. Code Chapter 123
(Standards for Contaminants, Particulate Matter Emissions), Section
123.14 – Outdoor Wood-Fired Boilers.  

The requirements of this SIP revision, beginning October 2, 2010
(effective date of the regulation), applies to the following:  

(1)  A person, manufacturer, supplier or distributor who sells, offers
for sale, leases or distributes an OWB for use in this Commonwealth. 

(2)  A person who installs an OWB in this Commonwealth.

(3)  A person who purchases, receives, leases, owns, uses or operates an
OWB in this Commonwealth.

The SIP revision does not apply to a person, manufacturer, supplier, or
distributor who sells, offers for sale, leases or distributes in this
Commonwealth a non-Phase 2 OWB, if the person, manufacturer, supplier or
distributor demonstrates the non-Phase 2 OWB is intended for shipment
and use outside of this Commonwealth.  The SIP revision also does not
apply to a permanently installed OWB that was installed prior to October
2, 2010, and is transferred to a new owner as a result of a real estate
transaction.

Another exemption in this SIP revision states that a person may not
sell, offer for sale, distribute or lease a non-Phase 2 OWB in this
Commonwealth, unless the OWB was manufactured, distributed, purchased or
leased, and received in this Commonwealth before May 31, 2011.  This
exemption shall remain in effect until May 31, 2011.  

A non-Phase 2 OWB purchased during the sell-through period shall meet
the following requirements:  

(1)  The non-Phase 2 OWB shall be installed a minimum of 150 feet from
the nearest property line.

(2)  Have a permanently attached stack that extends a minimum of 10 feet
above the ground, and is installed according to the manufacturer’s
specifications.

Furthermore, a person may not sell, offer for sale, distribute or
install an OWB for use in this Commonwealth, unless it is a Phase 2 OWB.
 A person may also not purchase, lease or receive an OWB for use in this
Commonwealth unless it is a Phase 2 OWB.

The requirements for a new Phase 2 OWB in this Commonwealth are the
following:

(1) A setback requirement for a new Phase 2 OWB is that a person may not
install a new Phase 2 OWB unless the boiler is installed a minimum of 50
feet from the nearest property line.  

(2) The stack height requirement for a new Phase 2 OWB is that a person
may not install, use or operate a new Phase 2 OWB, unless the boiler has
a permanently attached stack that extends a minimum of 10 feet above the
ground and be installed according to the manufacturer’s
specifications.

Furthermore, a person that owns, leases, uses, or operates an OWB in
this Commonwealth shall use only one or more of the following fuels:  

(1) Clean wood.

(2) Wood pellets made from clean wood.

(3) Home heating oil, natural gas or propane that complies with all
applicable sulfur limits and is used as a starter or supplemental fuel
for dual-fired OWBs.

(4) Other types of fuel approved in writing by PADEP upon receipt of a
written request.  

In addition, a person that owns, leases, uses, or operates an OWB in
this Commonwealth shall not burn a fuel or material in that OWB other
than those fuels listed above.

Lastly, a person shall not use or operate an OWB in this Commonwealth
unless it complies with applicable Commonwealth, county and local laws. 

 

C.  EPA EVALUATION

The emission standard established in the SIP revision is the Phase 2
emission standard described in the EPA voluntary program.  This SIP
revision is also based on the NESCUAM model rule that assisted PADEP in
adopting requirements that will reduce air pollution from OWBs.  The
PADEP’s SIP revision establishes emission limits and labeling
requirements for new OWBs and contains the following components for both
new and existing OWBs: setback requirements from property lines,
structures, and homes; stack height requirements; and distributor and
buyer notification requirements.

The Commonwealth will benefit from reduced emissions of fine particulate
matter (PM2.5) from OWBs by following the requirements of the Phase 2
emission standards in the EPA voluntary program, and the NESCUAM model
rule.  Attaining and maintaining levels of PM2.5 below the health-based
NAAQS will reduce premature mortality and other health effects
associated with PM2.5 exposure.  This SIP revision will reduce the
problems associated with the operation of OWBs, including smoke, odors
and burning prohibited fuels, including garbage, tires, and hazardous
waste.  Reductions in ambient levels of PM2.5 will promote improved
visibility, decreased soiling and materials damage, and decreased damage
to plants and trees.

D.  CONCLUSIONS AND RECOMMENDED AGENCY ACTION

The regulation to control PM2.5 emissions from OWBs adopted by the
Commonwealth of Pennsylvania will result in the reduction of PM2.5
emissions from the operation of OWBs and will help the Commonwealth in
attaining compliance with PM2.5 NAAQS.  EPA approval of the SIP revision
is recommended.

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