A stack test is a procedure for sampling a gas stream from a single sampling location at a facility, unit, or pollution control equipment. It is used to determine a pollutant emission rate, concentration, or parameter while the facility, unit, or pollution control equipment is operating at conditions that result in the measurement of the highest emission or parameter values (prior to any control device) or at other operating conditions approved by IDEM or U.S. EPA.
A test is comprised of three (3) sampling runs for a specified sampling time span. Additional conditions may be required by applicable rules, permit, or enforcement order. The testing shall be performed using sampling and analytical procedures approved by IDEM or U.S. EPA for the specific pollutant or parameter and facility, unit, pollution control equipment, process, or operation. A stack test is also known as an emission test, source sampling test, compliance test, or performance test.
Stack Test Forms, Guidance, and Information
- IDEM’s Stack Test Guide [ZIP]
- Indiana’s testing rules are found in the Indiana Administrative Code at 326 IAC 3-6, Source Sampling Procedures.
- U.S. EPA provides Maximum Achievable Control Technology (MACT) Standards. U.S. EPA’s Air Emission Measurement Center provides guidance including approved stack test methods.
- The Compliance Test Protocol (State Form 55003, available on the IDEM Agency Forms page) must be completed by a facility requesting IDEM's approval on tests for compliance, emission factors, or other tests before the tests are conducted. This form is for criteria pollutants and pollutants other than VOCs. The completed form may be submitted by U.S. Mail, email, or fax to the Compliance Data Section in IDEM’s Office of Air Quality. The Compliance Data Section must receive the form at least 35 days before the proposed test day.
- The VOC and Toxics Compliance Test Protocol (State Form 55008, available on the IDEM Agency Forms page) must be completed by a facility requesting IDEM's approval on tests for compliance, emission factors, or other tests before the tests are conducted. This form is for volatile organic compounds (VOCs) testing and air toxics testing. The completed form may be submitted by U.S. mail, email, or fax to the Compliance Data Section in IDEM’s Office of Air Quality. The Compliance Data Section must receive the form at least 35 days before the proposed test day. Note that National Emission Standards for Hazardous Air Pollutants (NESHAP) tests require the protocol be submitted 60 days before the proposed test day.
- Many facilities use professional air emissions testing services for stack testing. OAQ maintains a list of Environmental Consultants [PDF].
Compliance Assistance is available upon request.