MODOC COUNTY AIR POLLUTION CONTROL DISTRICT

RULE 8.6 - DIOXIN AIRBORNE TOXIC CONTROL MEASURE
(Amended Date Unknown)

The Dioxin Airborne Toxic Control Measure adopted by the California Air Resources Board pursuant to Health and Safety Code Section 39666, as set forth in Section 93104 of Titles 17 and 26 of the California Code of Regulations, effective July 13, 1991, is hereby adopted and incorporated by reference herein.

Section (b)(2)(B)

In order to make a more accurate determination of the combustion gas flow rate, Qc, which is used to determine residence time, the District specifies ARB Method 2 as the method of choice for measuring gas flow rate. In those cases where Method 2 cannot be used to measure Qc, Method 2 allows for alternatives.

In addition, the District is aware that Qc, measured at the sampling points must be corrected for the temperature and pressure differences that exist between the sampling point and the combustion chamber. It may be acceptable to assume constant pressure in some cases; however, the District may need to use an alternative approach when this assumption cannot be justified or when a measurement cannot be made.

Qc means the combustion gas flow through V expressed in actual cubic feet per second, which is measured according to ARB Method 2, after adjusting the measured flow rate to the maximum combustion chamber temperature (Tc) by using Tc instead of Tstd in the Method 2 calculation of Qc.

The volumetric flow rate measured at the sampling point must be adjusted to chamber pressures.

Alternative methods may he used if conditions for determining the combustion gas flow rate by Method 2 are unacceptable. The determination shall be within the guidelines of Method 2 and at the discretion of the Air Pollution Control Officer.

Section (b)(3)

The calculation of the gas flow rate, Qc, using combustion stoichiometry is one of the alternatives to measuring the gas flow rate. The District should revise the equation for Qc in the Control Measure to include a term to account for the contribution of the auxiliary fuel that is added to the combustion chamber. The equation for Qc would then be changed to:

Where:

Qstoiwf	=	lb-mole O2	x	lb waste	x	SCF O2	x	SCF air
		lb waste		min.		lb-mole O2		SCF O2
Qstoiaf	=	lb-mole O2	x	lb aux. fuel	x	SCF O2	x	SCF air
		lb aux. fuel		min.		lb-mole O2		SCF O2

EAwf = The excess air ratio (lbs excess air per lb theoretical air) for the waste fee expressed as a percentage.

EAwf = The excess air ratio (lbs excess air per lb theoretical air) for the auxiliary fuel expressed as a percentage.

TC = The maximum temperature, in degrees Fahrenheit, that has been reached in the incinerator.

Section (b)(4)

In order to estimate Qstoiwf and EAwf, a representative sample of the waste must be characterized by chemical analysis. If chemical analysis is not performed, the District will develop guidelines for assuring the representativeness of any proposed empirical method to estimate Qstoiwf and EAwf, since determining these parameters empirically can result in less accurate values.

Section (b)(5)

The District specifies that the high resolution mass spectrometry option of ARB Method 428 be used to determine compliance with the regulation, since facilities which comply with the 10 ng/kg standard would emit very low concentrations of dioxins and furans. High resolution mass spectrometry offers better selectivity and lower detection limits when compared to low resolution mass spectrometry.

Section (b)(6)

In those cases where incinerator operators are required to submit information in the permit application on the type and quantity of waste burned, the composition and representativeness of the waste for the compliance test will be determined by inspection and comparison with the permit application. When this comparison is not possible, the determination of composition and representativeness will be based on source generation data and inspection.