An OWB Program Experience

in Linn County, Iowa

November 8, 2012
December 21, 2010

“The [Wood-fired boilers] came under Linn County Public 

Health scrutiny over the past year after a handful of neighbors 

complained about smoke blowing into their yards.”

“Hodina worked for months on an ordinance that would 

bring the boilers into compliance without forcing owners to 

abandon what was in some cases a $10,000 investment.”

“The supervisors disregarded the recommendation and 

voted 4-1 on Aug. 27 to exempt existing boilers. The emissions 

rules would apply to new units, but complaints against existing 

ones would be handled case-by-case using nuisance laws.”
Ground Zero
Local SIP-Approved Rules

10.5 Permit Required

Exemptions

Fuel-burning equipment for indirect heating and re-heating furnaces or 

cooling units using natural or liquefied petroleum gas exclusively, with a 

capacity of less than 10 million BTU per hour input per combustion unit.

10.7 Visible Emissions

No person shall allow, cause, or permit the emission of visible air 

contaminants of a density or shade equal to or darker than that designated 

20 percent opacity

10.8 Emissions From Fuel-Burning Equipment

Applies to installations in which fuel is burned for the primary purpose of 

producing steam, hot water, hot air or other liquids, gases or solids and in 

the course of doing so, the products of combustion do not come into direct 

contact with process materials.

For heat inputs less than 10 million BTU, 0.6 lb/million BTU shall apply.

DS1
Slide 4

DS1 I would consider adding LCCO 10.7 [Visible Emissions]. The 20% opacity limit can be very effective in regulating dirty 

units if the owners fail to properly operate and maintain the OWB.

Dodge, Shane, 11/2/2012
Approach to Rule Modification

• Understand who has OWBs in Linn County and 

how they are used.

• Who is selling OWBs in Linn County and how 

are they marketing these units.

• Establish operating conditions for existing 

units to operate without violating NAAQS.

• Propose rules to:

– Grandfather existing units

– Require new units to meet SIP limit
Input from Iowa DNR

April 22, 2009

“Ordinances adopted by Linn County that are less stringent 

than the applicable state standard will not supersede the 

applicable state standard unless they are incorporated by EPA 

into Iowa's SIP. EPA may incorporate less stringent ordinances 

into the SIP on a case-by-case basis provided that a 

demonstration is made that the relaxation in the emission 

standard will not result in an adverse impact on air quality.

The DNR and EPA may both enforce the more stringent state

emission standard if the less stringent standard in the Linn 

County ordinance is not made federally enforceable through 

incorporation into the SIP.”
Modeling Demonstration

Establish siting and operating conditions for 

existing units to operate without violating 

NAAQS considering the following variables:

– Stack heights

– Setback distances

– Residential versus agricultural heat demand

– Seasonal variability
Annual Heat Degree Days

Month Heat Degree Days Annual Percentage

Jan 1341 21%

Feb 1269 20%

Mar 872 14%

Apr 384 6%

May 132 2%

Jun 0 0%

Jul 0 0%

Aug 0 0%

Sep 44 1%

Oct 315 5%

Nov 685 11%

Dec 1345 21%
Modeling Assumptions

• Used PM2.5 background as Design Value of 28 g/m3

and 10.2 g/m3

• In addition to PM2.5, evaluated CO, SO2, and NO2.

• Emission factor for uncertified boiler of 12.2 g/kg 

(1.44 lb/MMBtu) of wood burned.

• Wood firing rates based on heat demand were 

calculated in range of 51 to 153 MMBtu/yr

– 15 and 25 cords per year for agricultural setting

– 5.0 and 7.5 cords per year for residential setting
5 Cords/Year

Oct Nov Dec Jan Feb Mar Apr

lb/season 7.44 16.19 31.78 31.69 29.99 20.61 9.07

lb/day 0.2401 0.54 1.03 1.02 1.07 0.66 0.30

lb/hour 0.0100 0.02 0.04 0.04 0.04 0.03 0.01

gm/hr 4.5382 10.20 19.38 19.32 20.24 12.56 5.72

15 Cords/ Year

Oct Nov Dec Jan Feb Mar Apr

lb/season 22.33 48.56 95.35 95.07 89.96 61.82 27.22

lb/day 0.720 1.62 3.08 3.07 3.21 1.99 0.91

lb/hour 0.030 0.07 0.13 0.13 0.13 0.08 0.04

gm/hr 13.62 30.59 58.13 57.96 60.72 37.69 17.15

Seasonal Variability of Heat 

Demand & PM Emission Rates
“The Iowa Department of Natural Resources swooped in and 

put the brakes on Linn County’s plans to exempt existing woodfired boilers from a new ordinance regulating the units.

If the supervisors exempt the boilers, Fitzsimmons said, her 

agency would review Linn County’s air quality division and 

perhaps withdraw the state’s stamp of approval.

The supervisors responded Monday by postponing the 

second reading of the ordinance until Sept. 9, time enough to 

decide whether it’s possible to exempt existing boilers without 

losing funding for local air quality.”

December 21, 2010
Final Proposal

• All Boilers

– Registration permit for existing and new units

– Established “Nuisance Conditions” for all OWBs

– All new boilers must meet 0.6 lb/mmBtu for PM2.5

• Existing Boilers

– Agricultural Use

• Stack height of 15ft another residence within 500ft 

• Fuel usage limit restricted to 15 cords/year

DS3
Slide 12

DS3 The final proposal slides are a little confusing. All units must be registered - new and existing. Also, the set backs, stack 

heights and usage limits only apply to existing units that are not Phase 1 compliant. Phase 1 units, regardless of 

installation date are not subject to 10.8(3). 

Dodge, Shane, 11/2/2012
Final Proposal (continued)

• Existing Boilers (continued)

– Residential Use

• Sited no closer than 200 ft of the nearest property 

or 

• Have a stack height two feet higher than the peak of 

any roof structure that is located within 300ft.

• Fuel usage limit is restricted to 5 cords annually

• Cannot operate from May 15 to September 15.
Iowa Attorney General

Following a meeting with the Assistant Attorney General, letters were sent 

out to 21 outdoor wood boiler manufacturers who sell their products in Iowa, 

which stated:

“Our primary concerns relate to the ability of Iowa consumers to lawfully 

use your company's outdoor wood boiler products. As we understand it, 

the cost to a consumer of an outdoor wood boiler, on average, is in the 

range of $10,000 with costs of up to $50,000 for heavier users. Therefore, 

the consumer's ability to use the product lawfully is a material fact that 

may not be misrepresented to consumers or concealed from them 

pursuant to the Iowa Consumer Fraud Act, Iowa Code section 714.16. The 

Consumer Fraud Act is Iowa's civil consumer fraud law and is enforced by 

this office. In addition, as of July 1, 2009, Iowa consumers now also have

private remedies for consumer fraud pursuant to a new law, House File 

712.”
Today

• LCPH has had significant 

reduction in complaints.

• Some municipalities 

adopting more stringent 

requirements than county, 

with bans in residential 

neighborhoods

• Also very few new units 

being registered.

• 83 Registered Outdoor 

Wood Boilers: • Built and installed 2006 

and later

• Rated heat input of • 125,000 – 500,000 

Btu/hr

• Over 20 different 

manufactures each 

with different models

Linn County, Iowa
Contact Information

James Hodina

Environmental Manager

Air Pollution Control Officer

Linn County Public Health

501 13th Street NW

Cedar Rapids, Iowa 52404

james.hodina@linncounty.org

319-892-6010

www.linncleanair.org