R18-2-507. General Permit Variances

A. Where MACT (maximum achievable control technology) or HAPRACT (hazardous air 

pollutant reasonably available control technology) has been established in a general permit for 

a source category designated under R18-2-1702, the owner or operator of a source within that 

source category may apply for a variance from the standard by demonstrating compliance with 

R18-2-1708 at the time the source applies for coverage under the general permit.

B. If the owner or operator makes the showing required by R18-2-1708 and otherwise qualifies for 

the general permit, the Director shall, in accordance with the procedures established pursuant 

to this Article, approve the application and authorize operation under a variance from the 

standard of the general permit. 

C. Except as modified by the variance, the source shall comply with all conditions of the general 

permit.

D. A proposed variance to a standard in a general permit shall be subject to the public notice 

requirements of R18-2-330.

Historical Note

Adopted effective May 14, 1979 (Supp. 79-1). Amended effective July 9, 1980 (Supp. 80-4). 

Former Section R9-3-507 renumbered without change as Section R18-2-507 (Supp. 87-

3). Amended effective September 26, 1990 (Supp. 90-3). Former Section R18-2-507 

renumbered to R18-2-707; new Section R18-2-507 adopted effective November 15, 1993 

(Supp. 93-4). Amended by final rulemaking at 12 A.A.R. 1953, effective January 1, 2007 

(Supp. 06-2).
R18-2-707. Standards of Performance for Existing Sulfuric Acid Plants

A. Facilities that produce sulfuric acid by the contact process by burning elemental sulfur, alkylation acid, hydrogen sulfide, organic sulfide and mercaptans or

acid sludge shall not discharge into the atmosphere:

1. Greater than 2 kg of sulfur dioxide per metric ton (4 lbs/ton) of sulfuric acid produced (calculated as 100% H2SO4), or

2. Greater than 0.075 kg of sulfuric acid mist per metric ton (0.15 lbs/ton) or sulfuric acid produced (calculated as 100% H2SO4).

B. This Section shall not apply to metallurgical plants or other facilities where conversion to sulfuric acid is utilized as a means of controlling emissions to the

atmosphere of sulfur dioxide or other sulfur compounds.

C. A continuous monitoring system for the measurement of sulfur dioxide shall be installed, calibrated, maintained and operated by the owner or operator, in

accordance with R18-2-313.

D. The test methods and procedures required by this Section are as follows:

1. The reference methods in 40 CFR 60, Appendix A shall be used to determine compliance with standards prescribed in subsection (A) as follows:

a. Method 8 for concentration of SO2 and acid mist;

b. Method 1 for sample and velocity traverses;

c. Method 2 for velocity and volumetric flow rate;

d. Method 3 for gas analysis.

2. The moisture content can be considered to be zero. For Method 8 the sampling time for each run shall be at least 60 minutes and the minimum sample

volume shall be 1.15 dscm (40.6 dscf) except that smaller sampling times or sample volumes, when necessitated by process variables or other factors,

may be approved by the Director.

3. Acid production rate, expressed in metric tons per hour of 100% H2SO4, shall be both:

a. Determined during each testing period by suitable methods, and

b. Confirmed by a material balance over the production system.

4. Acid mist and sulfur dioxide emissions, expressed in g/metric ton of 100% H2SO4, shall be determined by dividing the emission rate in g/hr by the

acid production rate. The emission rate shall be determined by the equation, g/hr-Qs x c, where Qs = volumetric flow rate of the effluent in dscm/hr

as determined in accordance with subsection (D)(1)(c), and c = acid mist and SO2 concentrations in g/dscm as determined in accordance with

subsection (D)(1)(a).

Historical Note

Former Section R18-2-707 repealed effective September 26, 1990 (Supp. 90-3). New Section R18-2-707 renumbered from R18-2-507 effective

November 15, 1993 (Supp. 93-4).