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 Appendix A) or an equivalent test method approved by the Control Officer and 

the EPA Administrator; 

 c. in a manner that will produce visibility impairment that could threaten public 

safety. 

2. Failure to comply with these requirements shall presumptively constitute cause for the 

Control Officer or his authorized representative to order a halt to the offending activity. 

Failure by an owner, contractor or facility operator to respond to such an order from the 

Control Officer shall constitute a violation of this rule. 

3. Violations: Generally any land owner, contractor, or subcontractor operating on the job site, 

who violates any Pinal County Air Quality Control District rule may be subject to an order 

of abatement, a civil action for injunctive relief or civil penalties, or may be found guilty of 

a Class I Misdemeanor. 

4. Violation Exemptions: 

 a. Wind Event: exceedances of the opacity limit that occur due to a wind event shall 

be exempted from enforcement action if the owner/general contractor 

demonstrates all of the following conditions: 

 i. All control measures required in the registration acknowledgment were 

followed and one or more of the work practices were applied and maintained; 

 ii. The 20% opacity exceedance could not have been prevented by better 

application, implementation, operation or maintenance of the control 

measures; 

 iii. The occurrence of a wind event on the day(s) in question is documented by 

records of the Pinal County Air Quality Control District monitoring station in 

the affected area, from any other certified meteorological station, or by a 

wind instrument that is calibrated to the manufacturer' s standards and that is 

located at the site being investigated. 

 b. No opacity violation shall apply to emergency maintenance of flood control 

channels and water retention basins, provided that control measures were being 

implemented. 

5. Limited scope of rule 

Nothing in this rule shall authorize or permit any practice which is in violation of any 

statute, ordinance, rule or regulation. 

[Adopted December 13, 2000, and effective March 1, 2001. Amended December 4, 2002. Amended October 27, 2004. ] 

ARTICLE 4. NONATTAINMENT AREA RULES; DUSTPROOFING FOR 

COMMERCIAL PARKING, DRIVES AND YARDS 

4-4-100. General Provisions 

A. Intent. The intent of this Article is to avoid violations of the prevailing PM10 standard 

and additionally minimize nuisance impacts by improving control of excessive 

fugitive dust emissions from unpaved parking lots. 

B. Relationship to other rules. The provisions of this Article supplement and do not 

supplant the other provisions of these rules. 

C. Effective Date. Other than as specifically provided, rules set forth in this Article, and the 

repeal of any rules rescinded in conjunction with the amendment of this Article, shall 

become effective 60 days after final publication of a corresponding Notice of Final 

Rulemaking in the Arizona Administrative Register. 

D. Geographic Applicability 
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This Article applies in the Pinal County portion of the Phoenix PM10 Serious 

Nonattainment area, more specifically Township 1 North, Range 8 East, Gila & Salt 

River Base and Meridian ("T1N R8E"). 

E. Violations 

Failure by any person to comply with the applicable requirements of this Article shall 

constitute a violation subject to penalty as provided in these rules and A.R.S. Title 49, 

Chapter 3, Article 3, A.R.S. §49-471 et seq. 

[Adopted effective September 10, 2008. Amended June 3, 2009, effective August 26, 2009] 

4-4-110. Definitions 

As used in this Article: 

A. Hierarchy of definitions 

For purposes of this Article definitions shall be based on the following order of 

precedence: 

 1. Enumerated definitions under this rule; 

 2. Definitions in §4-7-210; 

 3. Definitions set forth elsewhere in these rules; and 

 4. The common and ordinary meaning of the term. 

B. Lot - A parcel of land identified on a final or parcel map recorded in the office of the 

Pinal County recorder with a separate and distinct number or letter. 

C. Low use unpaved parking lot - A lot on which vehicles are parked no more than thirtyfive (35) days during a calendar year. 

D. Motor vehicle - A self-propelled vehicle for use on the public roads and highways of the 

State of Arizona and required to be registered under the Arizona State Uniform Motor 

Vehicle Act, including any non-motorized attachments, such as, but not limited to, 

trailers or other conveyances which are connected to or propelled by the actual motorized 

portion of the vehicle. 

E. Owner and/or operator - Any person who owns, leases, operates, controls, maintains or 

supervises an unpaved parking lot surface subject to the requirements of this Article. 

F. Pavement - A traffic-bearing surface consisting of any of: 

 1. asphalt, 

 2. recycled asphalt, 

 3. concrete, 

 4. Penetration treatment of bituminous material and a seal coat of bituminous binder 

and mineral aggregate, commonly known as "double chip seal" or "asphalt rock 

dust palliative" ("ARDP"), 

 5. asphaltic concrete, 

 6. rubberized asphalt, or 

 7. other similar material. 

G. Property line - The boundaries of an area in which either a person causing the emission or 

a person allowing the emission has the legal use or possession of the property. Where 
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such property is divided into one or more sub-tenancies, the property line(s) shall refer to 

the boundaries dividing the areas of all sub-tenancies. 

H. Unpaved commercial parking lot - Any area that is not paved and that is used for parking, 

maneuvering, material handling, or storing motor vehicles and equipment. An unpaved 

commercial parking lot includes, but is not limited to, automobile impound yards, 

wrecking yards, automobile dismantling yards, salvage yards, material handling yards, 

and storage yards. For the purpose of this definition, maneuvering shall not include 

military maneuvers or exercises conducted on federal facilities. For purposes of Article 

4, an unpaved commercial parking lot does not include parking, maneuvering, ingress 

and egress areas at residential buildings with four or fewer units, which residential 

parking lots separately regulated under Article 5.

 [Adopted effective September 10, 2008. Amended June 3, 2009. effective August 26, 2009] 

4-4-120. Objective Standards 

 An Owner and/or Operator shall stabilize any affected unpaved commercial parking lot 

surface such that: 

A. [Silt Content/Silt Loading Limitations] Every unpaved commercial parking lot shall 

show compliance at all times with one of the following objective standards as assessed in 

accord with Article 9, §4-9-320.A: 

 1. Silt loading shall not exceed 0.33 oz/ft^2; or 

 2. Silt content shall not exceed 8% for parking areas. 

B. [Opacity Limitations] Observed opacity shall not exceed either of: 

1. 20% Internal Opacity Limitation. For any fugitive dust plume caused by 

vehicular movement, a limit of 20 percent opacity based on an intermittent 

opacity method, as determined by the applicable test method of Article 9. See 

§4-9-340.D.; or 

2. 0% Property Line Wind-Driven Opacity Limitation. The net opacity contribution 

from any unpaved commercial parking lot shall not violate a 0% opacity standard 

beyond the property line within which the emissions are generated for more than 

30 seconds in any continuous six-minute period. For purposes of this limitation, 

opacity shall be determined based on a time-aggregation method. See Article 9, 

§4-9-340.F. 

[Adopted effective September 10, 2008. Amended June 3, 2009. effective August 26, 2009] 

4-4-130. Work Practice Standards 

A. Commercial Unpaved Parking Lots 

At any unpaved commercial parking lot other than a low-use unpaved commercial 

parking lot, the Owner and/or Operator shall: 
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1. Restrict vehicle access to only those areas for which control measures have been 

taken. 

2. Dustproof the unpaved commercial parking lot with one of the following control 

measures: 

 a. Pave; 

 b. [Gravel surfacing] Uniformly apply and maintain surface gravel; or 

c. [Dust suppressants & trackout control] Apply dust suppressants other 

than water and install, maintain, and use a suitable trackout control 

system that controls and prevents trackout and/or removes particulate 

matter from the tires and the exterior surfaces of motor vehicles that 

traverse the site. 

 3. Make a record of the dustproofing action taken. 

B. Low-Use Unpaved Commercial Parking Lots 

 At any low-use unpaved commercial parking lot, the Owner and/or Operator shall: 

 

1. Restrict vehicle access to only those areas for which control measures have been 

taken. 

2. Dustproof the unpaved commercial parking lot with one of the following 

measures: 

 a. Pave; 

 b. [Gravel surfacing] Uniformly apply and maintain surface gravel; 

c. [Dust suppressants & trackout control] Apply dust suppressants other 

than water and install, maintain, and use a suitable trackout control 

system that controls and prevents trackout and/or removes particulate 

matter from the tires and the exterior surfaces of motor vehicles that 

traverse the site; or 

d. [Water & trackout control] Apply water and install, maintain, and use a 

suitable trackout control device that controls and prevents trackout 

and/or removes particulate matter from the tires and the exterior surfaces 

of motor vehicles that traverse the site. 

 3. Make a record of the dustproofing action taken. 

C. Compliance Determination 

Implementation of the work practice standards required under this section shall be 

deemed inadequate until the Owner and/or Operator achieves compliance with the 

objective standards of §4-4-120. 

D. Trackout Cleanup Requirement 

 If trackout occurs, the Owner and/or Operator shall: 
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 1. Repair and/or replace the control measure(s); 

2. Clean-up immediately such trackout from paved areas accessible to the public 

including curbs, gutters, and sidewalks when trackout exceeds a cumulative 

distance of 25 lineal feet; 

3. Clean-up all visible trackout from paved areas accessible to the public at the end 

of the day. 

 4. Make a record of the repair, replacement and/or cleanup action taken. 

[Adopted June 3, 2009, effective August 26, 2009. effective August 26, 2009.]

4-4-140. Recordkeeping and Records Retention 

A. Requirement to furnish records upon request. Upon verbal or written request by the 

Control Officer, the log or the records and supporting documentation required under this 

Article shall be provided as soon as possible but no later than 48 hours, excluding 

weekends. If the Control Officer is at the Site where requested records are kept, records 

shall be provided without delay. 

B. Records Retention. Any person subject to a record-keeping requirement shall retain 

copies of approved control measure implementation records, and all supporting 

documentation for at least two years from the date such records were initiated. 

[Adopted June 3, 2009, effective August 26, 2009. ]

ARTICLE 5. NONATTAINMENT AREA RULES; STABILIZATION FOR 

RESIDENTIAL PARKING AND DRIVES 

4-5-150. Stabilization for Residential Parking and Drives; Applicability 

A. Geographic Applicability. 

 The "affected area" under this rule includes the Pinal-County-portion of the Phoenix 

Planning Area Serious PM10 nonattainment Area, identified as Township 1 North, Range 8 

East, Gila & Salt River Base and Meridian. 

B. Affected Parcels; Residential Property. 

 Property subject to this rule: 

1. Includes any single deeded or platted parcel having built thereon a residential 

building or buildings with four or fewer residential units; 

2. Excludes any publicly owned right-of-way legally established and actually 

maintained for travel by the public; 

3. Excludes any right-of-way legally established to provide vehicular access to 

public utilities; and 
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4. Excludes earthmoving activity at a site, or that portion of a site, covered by 

mitigation requirements under dust registration issued by the Pinal County 

Control Officer. 

C. Affected Surfaces at a Residential Property. 

1. Affected surfaces include any areas in excess of 3,000 square feet utilized on a 

regular basis for parking, maneuvering or ingress and egress of on- or off-road 

vehicles. 

2. Undisturbed surfaces are not affected surfaces, but only if those undisturbed 

surfaces are fenced or otherwise clearly distinguished from affected surfaces. 

Delineated long-term storage stalls, where a vehicle, trailer or other item is stored 

and not normally removed and replaced more than once in a sixty-day period 

shall also be considered undisturbed surfaces. 

[Adopted effective September 10, 2008.] 

4-5-160. Residential Parking Control Requirement 

A. On and after the effective date, the owner and/or operator of any residential property shall 

install and maintain paving or a stabilization method for all affected surfaces. For purposes 

of this rule, "owner or operator" means any person who owns, leases, operates, controls, or 

supervises an affected area. 

B. For purposes of this rule, a stabilization method shall consist of one of the following, 

implemented in a manner that meets the maintenance standard of this rule: 

 1. Paving with asphaltic concrete; 

 2. Paving with Portland cement based concrete; 

3. Surfacing with a penetrating asphalt and a gravel surface, commonly known as 

chip sealing; 

4. Surfacing with and uniformly maintaining a two-inch deep layer of rock having a 

nominal size of 1/4" or larger; 

 5. Surfacing with a two-inch deep layer of recycled asphalt; 

 6. Watering with sufficient frequency so as to maintain a crust on the surface; 

7. Surfacing with any other surface treatment that has been approved in writing by 

the Pinal County Control Officer; or 

8. Initially, and at such other times as may be requested by the Control Officer, 

demonstrating to the satisfaction of the Pinal County Control Officer on a form 

as required by the Control Officer, that the average threshold friction velocity of 

the native soil surface, corrected for non-erodible elements, is at least 100 

cm/second. Threshold friction velocity shall be assessed in accord with 

§4-9-320.B.2. 
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C. Maintenance 

 Surface stabilization shall be maintained in a manner that prevents visible track-out in 

excess of ten feet in length. 

[Adopted effective September 10, 2008. Amended June 3, 2009. effective August 26, 2009.] 

4-5-170. Deferred enforcement date 

 The Control Officer shall commence enforcement of the requirements of this Article no 

sooner than October 1, 2009. 

[Adopted effective September 10, 2008.] 

ARTICLE 6. RESTRICTIONS ON VEHICLE PARKING AND USE ON VACANT LOTS 

4-6-200. Unpaved and Unstabilized Vacant Lots, Restriction on Vehicle Parking and Use; 

Applicability 

A. Geographic Applicability. 

1. The "affected area" under this rule includes the PM10-non-attainment-area 

portion of the Pinal-County-portion of Area A as defined at A.R.S. §49-541, 

including: 

 Township 1 north, range 8 east 

2. The "affected area" under this rule also includes the PM10-attainment-area 

portion of the Pinal-County-portion of Area A as defined at A.R.S. §49-541, 

including: 

 Township 1 north, range 8 east 

 Township 1 north, range 9 east 

 Township 1 south, range 8 east 

 Township 1 south, range 9 east 

 Township 2 south, range 8 east 

 Township 2 south, range 9 east 

 Township 3 south, range 7 east 

 Township 3 south, range 8 east 

 Township 3 south, range 9 east 

B. Affected Parcels; Vacant Lots. 

 Property subject to this rule includes any unpaved or unstabilized vacant lot. For purposes 

of this rule, a vacant lot constitutes a parcel that is not occupied by a structure properly 

permitted under the prevailing building code. For purposes of this rule, a stabilized surface 

constitutes a surface that does not produce visible trackout when a vehicle leaves the lot, 

and shall consist of one of the following: 

 1. Paving with asphaltic concrete; 

 2. Paving with Portland cement based concrete; 
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3. Surfacing with a penetrating asphalt and a gravel surface, commonly known as 

chip sealing; 

4. Surfacing with and uniformly maintaining a two-inch deep layer of rock having a 

nominal size of 1/4" or larger; 

 5. Surfacing with a two-inch deep layer of recycled asphalt; 

 6. Watering with sufficient frequency so as to maintain a crust on the surface; 

7. Surfacing with any other surface treatment that has been approved by the Pinal 

County Control Officer; or 

8. Initially, and at such other times as may be requested by the Control Officer, 

demonstrating to the satisfaction of the Pinal County Control Officer on a form 

as required by the Control Officer and pursuant to a test method approved by the 

Control Officer, that the average threshold friction velocity of the native soil 

surface, corrected for non-erodible elements, is at least 100 cm/second. 

Threshold friction velocity shall be assessed in accord with §4-9-300. 

[Adopted effective September 10, 2008.] 

4-6-210. Control Requirement 

1. A property owner or operator shall restrict vehicle parking and use on an 

unstabilized vacant lot. For purposes of this rule, "owner or operator" means any 

person who owns, leases, operates, controls, or supervises an affected area. 

2. No person shall park any motor vehicle on any vacant unstabilized lot without 

the permission of the owner or operator. The vehicle operator and all persons in 

whose names the vehicle is registered shall be jointly and severally prima facie 

responsible for any violation of this prohibition. 

3. The requirements under this rule shall not apply to an owner, operator, or anyone 

using or parking a vehicle with the permission of the owner or operator. Under 

this subsection, a lessee or an agent of the owner is an operator. Permission under 

this subparagraph includes access privileges expressly granted by statute, rule, 

ordinance or regulation of a federal or state agency or political subdivision, as 

well as access privileges granted as an attribute of any license issued by any such 

governmental body. 

[Adopted effective September 10, 2008.] 

ARTICLE 7. CONSTRUCTION SITES IN NONATTAINMENT AREAS – FUGITIVE 

DUST 

4-7-210. Definitions

As used in this Article: 

1. "Aggregate area" means, for purposes of assessing either disturbed area or overall project 

size, the relevant area or areas under common control and contained within a planned 

area development, within a legal subdivision, and/or adjoining parcels undergoing 
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concurrent Development Activity. Parcels shall be considered adjoining if they are either 

contiguous or separated only by a privately or publicly owned easement or right-of-way. 

2. "Bulk material" as used in this rule, means any material including but not limited to earth, 

rock, silt, sediment, sand, gravel, soil, fill, aggregate less than 2 inches in length or 

diameter, dirt, mud, grubbed materials, cinders, pumice, demolition debris, and dry 

concrete, which are capable of producing fugitive dust at an industrial, institutional, 

commercial, governmental, construction and/or demolition site. 

3. "Construction" means building, maintaining or modifying a capital improvement resting 

upon, connected to or buried in the earth. Construction includes, but is not limited to, 

building construction, installing underground utilities, installing above-ground utilities, 

and building physical infrastructure including roads, highways, railways, flood structures, 

drainage works and irrigation works. Notwithstanding any other exemption under these 

rules, weed abatement by discing or blading and conducted for the purpose of enabling 

Development Activity or maintaining a Site shall qualify as construction. 

4. "Development Activity" or "Development Activities" are defined as follows: 

A. Development Activity includes: 

 1. Earthmoving; 

 2. Construction; 

 3. When conducted on a Site, any of: 

a. Use of vehicles or self-propelled equipment for material 

handling or storage off of a dustproof paved surface; 

b. Use of vehicles or self-propelled equipment for transporting 

materials or personnel off of a dustproof paved surface; 

c. Parking a vehicle or self-propelled equipment off of a dustproof 

paved surface; 

 4. Generating trackout as a result of any other Development Activity. 

B. Notwithstanding subparagraph A., Development Activities shall not include: 

 1. Normal farm cultural practices, including leveling of fields. 

2. Permit-regulated non-fugitive emission points and permit-regulated 

fugitive emission sources at any stationary facility operating under 

authority of a permit issued pursuant to ARS §§49-426 or 49-480, 

provided that this Article shall apply to Development Activity not 

specifically regulated under the permit. 

3. Permit-regulated non-fugitive emission points at a portable source 

operating on a Site in support of Development Activity otherwise 

regulated under this Article pursuant to a permit issued pursuant to ARS 

§§49-426 or 49-480, except to the extent that operation of such portable 

source is conducted in support of Development Activity otherwise 
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regulated under this Article, in which case this Article shall still apply to 

such a permitted portable source with respect to fugitive emissions from 

any source-specific Development Activity as defined under this Article. 

4. Emergency response activities that may disturb the soil conducted by any 

utility or government agency in order to prevent public injury or to 

restore critical utilities to functional status. For purposes of this 

subsection, an emergency response must address a situation arising from 

a sudden and unforeseeable event beyond the control of the Owner 

and/or Operator, including acts of God. Activities by an Owner and/or 

Operator to address a disturbance resulting from improperly designed 

equipment, lack of preventative maintenance, careless or improper 

operation or operator error shall not qualify as an emergency response. 

5. Normal surface maintenance of established roads, established utility 

easements, established traveled rights-of-way and established access 

roads does not constitute development, but only if such maintenance is 

not part of a larger project and: 

a. Is not within a Site that is otherwise subject to a Site Permit 

requirement; and 

b. Such maintenance does not involve cutting, filling or the import 

or export of material. 

 

6. Hauling activities outside of a Site, other than as regulated under projectlinked trackout provisions of these rules and under §4-7-230.D pertaining 

to haulage between portions of a Site that straddles a roadway. 

7. Weed abatement by discing or blading, subject to the limitations of §§4-

7-210.3 and 4-7-210.7. 

5. "Disturbed surface" or "disturbed area" means any portion of the earth's surface, or 

material placed on the earth's surface, that has been physically moved, uncovered, 

destabilized, or otherwise modified from its undisturbed natural condition, thereby 

increasing the potential for emission of fugitive dust. 

A. If a Site contains disturbed surfaces areas exhibiting visibly distinguishable soils, 

vegetative cover, or other stabilization characteristics, the Owner and/or Operator 

shall treat each such distinguishable area separately for purposes of assessing the 

necessary stabilization for that soil type or condition. 

B. For trenches that are less than four feet in depth, it is assumed that a six (6) foot 

wide path of surface material will be disturbed as the trench is dug. Once the 

trench exceeds a length of 726 feet, 0.1 acres of surface area has been disturbed. 

For trenches that are four feet or greater in depth, it is assumed that a twelve (12) 

foot wide path of surface material will be disturbed as the trench is dug. Once 

the trench exceeds a length of 363 feet, 0.1 acres of surface area have been 

disturbed. If the registrant identifies situations in which the amount of surface 

area should be calculated differently, a case-by-case determination would be 

made. 
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C. For calculations of the projected disturbed surface areas that will result from land 

clearing or earthmoving activities, a minimum of 25 feet will be added to each 

dimension of all structures, driveways, concrete pads, and other construction 

projects being built on the Site to allow for an equipment utilization zone. 

D. Surfaces that have been stabilized to meet at least one of the stabilization 

standards of §4-7-226.D shall no longer be considered disturbed. 

6. "Dust suppressant" means water, hygroscopic material, solution of water and chemical 

surfactant, foam, non-toxic chemical stabilizer or any other dust palliative, which is not 

prohibited for ground surface application by the U.S. Environmental Protection Agency 

(EPA) or the Arizona Department of Environmental Quality (ADEQ) or any applicable 

law, rule, or regulation, as a treatment material for reducing fugitive dust emissions. 

7. "Earthmoving" means use of vehicles or self-propelled equipment for: land stripping; 

trenching; grading; cutting and filling earthen materials; excavating; land leveling; 

drilling; back filling; contouring the earth; open stockpiling of bulk materials; loading 

or unloading bulk material; grubbing foundations or slabs; demolition; or any of the 

foregoing in connection with landscaping a Site. Blasting operations shall constitute 

earthmoving. Notwithstanding any other exemption under these rules, weed abatement 

by discing or blading and conducted for the purpose of enabling other earthmoving 

activity shall qualify as earthmoving. 

8. "End of workday" means the end of a working period that may include one or more work 

shifts. If working 24 hours a day, the end of a working period shall be considered no 

later than 8 p.m. 

9. "Fugitive dust" as used in this rule, means regulated particulate matter, which is not 

collected by a capture system, which is entrained in the ambient air, and which is caused 

from human and/or natural activities, such as but not limited to, movement of soils, 

vehicles, equipment, blasting, and wind. For the purpose of this rule, fugitive dust does 

not include particulate matter emitted directly from the exhaust of motor vehicles and 

other internal combustion engines, from portable brazing, soldering, or welding 

equipment, and from piledrivers. 

10. "Net opacity contribution" means the difference between opacity leaving the Site and 

opacity entering the Site. 

11. "Objective requirements" or "objective standards" mean those standards which either 

establish a numerical performance standard, or which have a formal compliance 

assessment method established under this Article. Examples include opacity standards, 

surface stabilization standards and length and pack-thickness limitations on visible 

trackout. 

12. "Opacity" as used in this rule, means the degree to which emissions reduce the 

transmission of light and obscure the view of an object in the background. See Article 9 

for specific methods for assessing opacity. 
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13. "Owner and/or Operator" means any person who leases, operates, controls, or supervises 

a Development Activity subject to any requirements of this Article and includes, but is 

not limited to, the owner, lessee, developer, responsible official, permit applicant, permit 

holder, general contractor, prime contractor, supervisor or management company of or 

for a Development Activity or Site. 

14. "PAD" means an approved planned area development approved by a political subdivision 

pursuant to statutory authority. 

15. "Paved public roadway" means either: 

A. A publicly owned paved roadway, as evidenced by a formal acceptance by the 

state or a political subdivision of the state of either: 

 1. An on-going maintenance obligation for the roadway; or 

 2. A title or easement for the roadway; or 

B. Within a PAD or subdivision, a paved private roadway that is open to travel by 

the public. Where active construction operations continue within a PAD or 

subdivision, the permittee may post signs to close selected paved roadways 

within the still-constructing areas to travel by the public. However, at least one 

road must furnish required paved access to every parcel within the PAD or 

subdivision that has received a certificate of occupancy, and every such required 

paved access road shall constitute a "paved public roadway" notwithstanding any 

signage to the contrary. 

16. "Permit," for purposes of this Article, means a Site Permit. 

17. "Permittee" means the person or legal entity who has obtained a Site Permit. 

18. "Road Construction" as used in this rule, means the use of any equipment for the paving 

or new construction of a road surface, street or highway. 

19. "Road Maintenance" as used in this rule, means the use of any equipment for the repair 

and preservation of an old road surface, street or highway. 

20. "Silt" means any aggregate material with a particle size less than 75 micrometers in 

diameter, which passes through a No. 200 Sieve. 

21. "Site" means any lot, parcel, easement, or right-of-way where Earthmoving or 

Construction occurs. 

22. "Site Permit" means a permit as defined in §§4-7-234, 4-7-238 and/or 4-7-242. 

23. "Source" as used in this Article means the Site which is under common control or 

ownership, and any fixed or moveable object or surface on such Site which is a potential 

point of origin of fugitive dust. 
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24. "Stockpile" as used in this rule, means an open storage pile with an open accumulation of 

bulk material with a 5% or greater silt content that has a total surface area of 150 square 

feet or more and that at any one point attains a height of three feet. Silt content shall be 

assumed to be 5% or greater unless the affected party can show, by: testing in 

accordance with ASTM method C136-96a; or testing by other equivalent method 

approved in writing by the Control Officer and the EPA Administrator, that the silt 

content is less than 5%. 

25. "Subdivision" means a platted subdivision. 

26. "Suppressant" means dust suppressant. 

27. "Trackout" means visible material deposited onto any paved public roadway, as defined 

in this Article, by traffic leaving a Site. 

28. "Unpaved haul/access road" as used in this rule, means any on-site unpaved road used by 

commercial, industrial, institutional, and/or governmental traffic. 

29. "Unpaved road" as used in this rule, means any road or equipment path that is not paved. 

For the purpose of this rule, an unpaved road is not a horse trail, hiking path, bicycle 

path, or other similar path used exclusively for purposes other than travel by motor 

vehicles. 

30. "Work practice standards" mean those standards which have neither a numerical 

performance standard or a compliance assessment method established. Compliance with 

work practice standards is assessed on a pass/fail basis. 

[ Adopted June 3, 2009, effective August 26, 2009]

4-7-214. General Provisions

A. Intent. The intent of this Article is to avoid violations of the prevailing PM10 standard 

and additionally minimize nuisance impacts by improving control of excessive fugitive 

dust emissions. The Article focuses on emissions from process activity, site activity and 

a lack of adequate surface stabilization, all associated with construction, earthwork or 

land development. 

B. Relationship to other rules. Other than as provided in subsection D below, the provisions 

of this Article supplement and do not supplant the other provisions of these rules. 

C. Effective Date. The rules set forth in this Article shall become effective 60 days after the 

publication of a notice of final rulemaking in the Arizona Administrative Register. 

D. Geographic Applicability 

This Article applies in the Pinal County portion of the Phoenix PM10 Serious 

Nonattainment area, more specifically Township 1 North, Range 8 East, Gila & Salt 

River Base and Meridian ("T1N R8E"). In the affected region, this Article supplants the 

generally applicable dust registration program of Chapter 4, Article 3 of this Code. 
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E. Violations 

Failure by any person to comply with the applicable requirements of this Article shall 

constitute a violation subject to penalty as provided in these rules and A.R.S. Title 49, 

Chapter 3, Article 3, A.R.S. §49-471 et seq. 

[ Adopted June 3, 2009, effective August 26, 2009]

4-7-218. Applicability; Development Activity

A. The objective standards of §4-7-226 and the work practice requirements of §4-7-230 shall 

apply to Development Activity at any Site, regardless of the size of the disturbed area. 

B. Unless Development Activity qualifies for coverage under an Area Block Permit, the Site 

Permit requirements of §§4-7-234 and 4-7-238 apply to any Site which includes an 

aggregate area of more than 0.1 acres that has been or will be disturbed by Development 

Activity. 

C. The Area Block Permit requirements under §§4-7-234 and 4-7-242 apply to any political 

subdivisions and Public Utility Corporations which will regularly engage in Development 

Activity that will disturb an area of 0.1 acres or more. 

[ Adopted June 3, 2009, effective August 26, 2009]

4-7-222. Owner and/or Operator Liability 

A. Onset. Compliance with the requirements of this Article shall commence on or before 

the date when Development Activity begins on the Site. 

B. Duration and Termination. Obligations continue until all of the following occur: 

 1. Development Activity has ceased. 

2. All disturbed portions of the Site have been stabilized as required under §4-7-

226. 

 3. The Control Officer approves closure of the construction permit. 

C. Obligations. With respect to any Site, an Owner and/or Operator shall: 

1. Obtain, or cause to be obtained, and be liable for any failure to obtain, a Permit 

pursuant to §§4-7-238 or 4-7-242 for any Site with a disturbed area exceeding 0.1 

acres. 

2. Until termination as provided in this section, comply with or cause compliance 

with, and be liable for any person's violating or failing to comply with, any of: 

 a. The applicable objective site standards of §4-7-226. 

 b. The applicable obligatory site work practice standards of §4-7-230. 

 c. The requirement that a Site Permit be approved prior to any person 

engaging in earthmoving that will cause more than 0.1 acre of disturbed 

area. 

d. The provisions of any Site Permit for the Site approved pursuant to §§4-

7-238 or 4-7-242, including the requirements of the Dust Management 

Plan included within that permit. 
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D. Affirmative Defense for Wind-Driven Opacity Violations 

An Owner and/or Operator shall have an affirmative defense to any enforcement action 

for opacity violations resulting solely from wind acting upon a stabilized surface, 

provided that: 

1. The Owner and/or Operator can show that the prevailing wind speed exceeded 25 

m.p.h. when averaged over one hour, as measured by: 

 a. A Pinal County Air Quality monitoring station in the affected area; 

 b. Any other certified meteorological station in the affected area; or 

c. A wind-speed instrument calibrated to the manufacturer's standards and 

operated on-site. 

 2. The Owner and/or Operator can show through written records or otherwise that: 

 a. The requirements of the Site dust control plan were being met; and 

b. The offending areas of the Site were maintained in a condition adequate 

to meet relevant stabilization requirements under §§4-7-226.C and 4-7-

226.D. 

3. The Owner and/or Operator can show that for any areas subject to any 

Development Activity that continues during windy conditions, including but not 

limited to earthmoving, equipment movement or site traffic, in addition to any 

other required control measures one or more of the following measures were 

applied and maintained: 

a. All Development Activity, other than continued application of water for 

dust suppression and site stabilization purposes, has ceased; 

b. Apply water or other suitable dust suppressant at least twice per hour to 

affected areas; 

c. For areas that are shown to have an optimum moisture content of less 

than 12%, as determined by ASTM Method D1557-02el or other 

equivalent methods approved by the Control Officer and the 

Administrator, maintain at least 70% of the optimum soil moisture 

content, as determined by ASTM Method D2216-05 or other equivalent 

methods approved by the Control Officer and the Administrator; 

d. For areas where the optimum moisture content has not been shown to be 

less than 12%, maintain soil moisture content at a minimum of 12%, as 

determined by ASTM Method D2216-05 or other equivalent methods 

approved by the Control Officer and the Administrator. 

4. The Owner and/or Operator can show that for temporary disturbed surfaces, 

including but not limited to, after work hours, weekends and holidays, in addition 

to any other required control measures, the following measures were applied as 

appropriate: 

 a. For open storage piles, either: 

 i. Apply water on all open storage piles at least twice per hour; or 

ii. Cover open storage piles with tarps, plastic, or other material 

such that the wind will not remove the covering(s). 

 b. For other temporary disturbed surfaces, either: 

i. Uniformly apply and maintain surface gravel or dust 

suppressants; or 

ii. Apply water to disturbed surface areas at least three times per 

day, but if disturbed surface areas continue to show evidence of 

wind-blown dust, increase watering frequency to four times per 

day. 

[ Adopted June 3, 2009, effective August 26, 2009]
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4-7-226. Objective Standards; Sites 

A. Opacity Limitations. Opacity directly attributable to Development Activity or resulting 

from any disturbed areas caused by Development Activity shall not exceed any of the 

following limitations: 

1. 0% Property Line Opacity Limitation. Subject to the exemptions below, the net 

opacity contribution from any Development Activity or disturbed areas caused by 

Development Activity shall not violate a 0% opacity standard at the boundary of 

the parcel for more than 30 seconds in any continuous six-minute period. 

a. This limitation shall not apply to earthmoving operations conducted 

within 25 feet of a parcel boundary. 

b. For purposes of this property line opacity standard, opacity shall be 

determined based on a time-aggregation method. See Article 9, §4-9-

340.F. 

2. [Continuous Plume Limitation] Opacity shall not exceed 20% opacity for any 

continuous plume, as assessed by a time-averaging method, based on 

observations every 15 seconds over a 3-minute span, as defined in Article 9, §4-

9-340.E. 

3. [Intermittent Plume Limitation] Opacity shall not exceed 20% opacity for any 

intermittent plume, as assessed by the average of a set of six paired observations, 

spaced by five seconds and conducted within a one-hour period, as defined by the 

appropriate test method in Article 9, see §§4-9-340.C and 4-9-340.D. 

4. [Wind Events] The opacity limitations of this rule shall apply to wind-driven 

emissions, provided that an Owner and/or Operator may have an affirmative 

defense to any violation upon making a showing as required under §4-7-222. 

B. Trackout Limitations. 

1. [Basic Limitation] Continuous visible trackout from any Site onto a paved public 

roadway shall not exceed 25' in length or exhibit a trackout pack-depth greater 

than 0.25". 

2. On-site Trackout Control System. For any period of time when a project has 

more than two acres of area disturbed, or on any day that more than 100 cubic 

yards of bulk material is shipping in or out of the Site, install and maintain a 

trackout control system that prevents trackout. 

 3. Trackout Control System Options. 

Where a trackout control system is required, install and maintain at least one of 

the following system options. 

 a. Presumptively acceptable systems. 
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The following systems shall be acceptable options in a dust mitigation 

plan: 

i. Rumble strips - 25 foot length. For use of grizzlies or other 

similar devices designed to remove dirt/mud from tires, the devices 

shall extend from the intersection with the public paved road 

surface for a distance of at least 25 feet, and cover the full width of 

the unpaved exit surface for at least 25 feet. 

ii. Gravel pads - 50 foot length. For use of gravel pads, coverage 

with gravel shall be at least one inch or larger in diameter and at 

least 3 inches deep, shall extend from the intersection with the 

public paved road surface for a distance of at least 50 feet, and 

cover the full width of the unpaved exit surface for at least 50 feet. 

Any gravel deposited onto a public paved road travel lane or 

shoulder must be removed at the end of the workday or 

immediately following the last vehicle using the gravel pad, or at 

least once every 24 hours, whichever occurs first. 

iii. Internal paving - 100 feet. For use of paving, paved surfaces shall 

extend from the intersection with the paved public road surface for 

a distance of at least 100 feet, and cover the full width of the 

unpaved access road for that distance to allow mud and dirt to drop 

off of vehicles before exiting the Site. Mud and dirt deposits 

accumulating on paved interior roads shall be removed with 

sufficient frequency, but not less frequently than once per 

workday, to prevent carryout and trackout onto a paved public 

road. 

iv. [Wheel wash system] At all exits onto paved areas accessible to 

the public, install a wheel wash system. 

 B. Alternative systems. 

As an alternative, the Site Permit dust control plan may propose some other 

system for controlling trackout, provided that visible trackout from such system 

shall not exceed 5' in length onto a paved public road. 

C. Active Area Stabilization Requirements 

 1. Applicability; Affected Areas 

Active area stabilization requirements apply to disturbed areas affected by on-site 

parking, vehicular traffic, equipment traffic, material transport, or equipment 

transport. 

 2. [Objective Standards] Comply with each of the following requirements: 
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a. Every disturbed parking area and/or working area shall show compliance 

at all times with one of the following objective standards as assessed in 

accord with Article 9, §4-9-320.A: 

 i. Silt loading shall not exceed 0.33 oz/ft^2; or 

 ii. Silt content shall not exceed 8% for parking and working areas. 

b. Every disturbed roadway area shall show compliance at all times with 

one of the following objective standards as assessed in accord with 

Article 9, §4-9-320.A: 

 i. Silt loading shall not exceed 0.33 oz/ft^2; or 

 ii. Silt content shall not exceed 6% for roads. 

c. All disturbed areas other than parking areas, working areas or roadway 

areas affected under this Active Area Stabilization requirement shall be 

stabilized such that every disturbed area shows compliance at all times 

with the drop ball test of Article 9, §4-9-320.B.1. 

3. [Maintenance Obligation] Maintain active area stabilization to meet the 

foregoing standards until the activity ceases and the affected area of the Site has 

been stabilized to meet the post-operation stabilization standards of §4-7-226.D. 

D. Stabilization Requirement for Inactive and Post-operation Areas 

Any disturbed surface area on which no activity is occurring shall meet at least one of the 

standards described below. If areas of the Site exhibit visibly distinguishable surface 

characteristics, each area shall be separately assessed for stability. Stability shall be 

assessed in accord with the appropriate test methods described in Article 9, §4-9-320.B. 

Failure to maintain a disturbed surface area on which no activity is occurring shall be 

considered in violation of this rule unless the area is maintained in a manner that meets at 

least one of the standards listed below, as applicable. 

1. [Drop Ball Test] Maintain stabilization or a soil crust adequate to pass the drop 

ball test; 

2. [Maintain 100 cm/sec. threshold friction velocity] Maintain a threshold friction 

velocity (TFV) for disturbed surface areas corrected for non-erodible elements of 

100 cm/second or higher; 

3. [Maintain 50% flat vegetative cover] Maintain a flat vegetative cover (i.e., 

attached (rooted) vegetation or unattached vegetative debris lying on the surface 

with a predominant horizontal orientation that is not subject to movement by 

wind) that is equal to at least 50%; 

4. [Maintain 30% standing vegetative cover] Maintain a standing vegetative cover 

(i.e., vegetation that is attached (rooted) with a predominant vertical orientation) 

that is equal to or greater than 30%; 

5. [Maintain 10% standing vegetative cover and 43 cm/sec. TFV] Maintain a 

standing vegetative cover (i.e., vegetation that is attached (rooted) with a 

predominant vertical orientation) that is equal to or greater than 10% and where 

the threshold friction velocity is equal to or greater than 43 cm/second when 

corrected for non-erodible elements; 
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6. [Minimum non-erodible element cover] Maintain a percent cover that is equal to 

or greater than 10% for non-erodible elements as measured by the "rock test"; or 

7. [Implement an approved alternative] Comply with a standard of an alternative 

test method, upon obtaining the written approval from the Control Officer and 

the Administrator. 

E. Duration of Stabilization Obligation. 

1. Unpermitted Sites. For any unpermitted Site, maintain the stabilization standards 

of §4-7-226.D until Development Activity is complete. 

2. Sites Subject to a Block Permit. For any unpermitted Site, maintain the 

stabilization standards of §4-7-226.D until Development Activity is complete. 

3. Other Permitted Sites. For any other Site subject to permit requirement, maintain 

the stabilization standards of §4-7-226.D until the Control Officer approves 

closure of the Site Permit under Rule §4-7-238. 

[ Adopted June 3, 2009, effective August 26, 2009]

4-7-230. Obligatory Work Practice Standards; Sites 

A. Project Access Control. 

 

Define, clearly mark, and enforce ingress and egress points for traffic into and out of the 

Site. 

B. Dust Suppression for Inactive and Post-operation Areas and Roadways 

 For all inactive and post-operation-areas and -roadways within the Site: 

1. Restrict access, and pave, apply gravel or apply a suitable dust suppressant other 

than water; 

2. Apply water and prevent access by fences, ditches, vegetation, berms, or other 

suitable barrier or means sufficient to prevent trespass as approved by the Control 

Officer; or 

 3. Establish a vegetative cover in accord with §4-7-226.D. 

C. Bulk Material Stacking and Stockpiling Operations 

1. At least one of the following control measures shall be implemented during bulk 

material stacking, loading and unloading operations: 

a. Spray material with water, as necessary, prior to stacking, loading and 

unloading and/or while stacking, loading and unloading; or 

b. Spray material with a dust suppressant other than water, as necessary, 

prior to stacking, loading, and unloading and/or while stacking, loading 

and unloading. 
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2. When not conducting stacking, loading or unloading operations, implement at 

least one of the following control measures with respect to a stockpile: 

a. Cover all open storage piles with a tarp, plastic, or other material to 

prevent wind from removing the covering(s)/such that the covering(s) 

will not be dislodged by the wind; or 

b. Apply water to maintain a soil moisture content at a minimum of 12%, as 

determined by ASTM Method D2216-05 or other equivalent methods 

approved by the Control Officer and the Administrator. For areas that 

have an optimum moisture content of less than 12% as determined by 

ASTM Method D1557-02el or other equivalent methods approved by the 

Control Officer and the Administrator, maintain at least 70% of the 

optimum soil moisture content; or 

 c. Maintain a soil crust; or 

d. Implement either of the control measures in preceding subsection .b or .c, 

and construct and maintain wind barriers, storage silos, or a three-sided 

enclosure with walls, whose length is no less than equal to the length of 

the pile, whose distance from the pile is not more than twice the height of 

the pile, whose height is equal to the pile height, and whose porosity is 

no more than 50%. 

D. Trackout; Monitoring and Cleanup. 

 

 1. Monitor trackout length at each egress point. 

2. Immediately clean up any trackout that violates the length or pack-thickness 

limitations of §4-7-226.B.1. 

 3. Remove all visible trackout at the close of each workday and/or each work shift. 

E. Signage 

At any Site that is five acres or larger, erect a project information sign at the main 

entrance that is visible to the public or at each end of the road construction Site. The sign 

shall be a minimum of 24 inches tall by 30 inches wide, have a white background, and 

have the words "DUST CONTROL" shown in black block lettering which is at least four 

inches high, and shall contain the following information in legible fashion" 

 1. Project Name 

 2. Name and phone number of person(s) responsible for conducting project 

3. Text stating: "Dust Complaints? Call Pinal County Air Quality Control District 

at 

(520) 866-6929." 

F. Training 

 1. Dust Coordinator 

On any Site, or any contiguous combination of Sites under common control, 

having five acres or more of disturbed surface area subject to a Site Permit 

requirement, assure that at all times during earthmoving activity operations 

related to the purposes for which an Site Permit is required, have on-site at least 
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one individual qualified under a Control-Officer-approved Dust Control 

Coordinator training program. 

 2. Superintendent and Water Pull Drivers 

 

Assure that the site superintendent or other designated on-site representative of 

the Site Permit holder, and any water truck or water pull driver maintaining 

surface stabilization shall have successfully completed a Control-Officerapproved Basic Dust Control Training Class. 

G. Conformance with Project Access Control. 

Drivers, contractors, subcontractors, and materialmen shall utilize only the ingress and 

egress defined by the Owner and/or Operator. 

H. Dust Suppression for Active Working Areas, Parking Areas and Roadways 

To manage dust from working areas, including disturbed areas affected by on-site 

parking, vehicular traffic, equipment traffic, material transport, or equipment transport 

and roadways, at least one of the following measures shall be implemented: 

 1. Apply water so that the surface is visibly moist; 

 2. Apply and maintain a suitable dust suppressant other than water; 

3. Limit speed to 15 mph and traffic to no more than 20 trips/day, provided reliance 

on this measure requires that the Dust Management Plan include a traffic 

management plan that details how speed and daily trips will be limited; 

 4. Apply gravel, recycled asphalt or other suitable material; or 

 5. Pave. 

I. Dust Suppression During Bulk Excavation Operations 

1. Pre-watering shall be applied before commencing earthmoving cut-operations; 

and 

2. Water shall be applied during activity as required to limit particulate emissions to 

avoid opacity limit violations. 

J. Project-internal Load Stabilization 

Load stabilization shall be required during haulage of bulk excavated materials internally 

within a Site and not crossing a paved public road by implementing at least one of the 

following measures: 

 1. Limit speed to 15 miles per hour; 

 2. Stabilize loads with water or a dust suppressant; or 
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 3. Cover the load with a tarp or other suitable dust and wind impermeable material. 

K. Roadway-Crossing Load-Stabilization 

Load stabilization shall be required during haulage of bulk excavated materials across a 

paved public road, by implementing all of the following limitations: 

 1. Load all haul trucks such that the freeboard is not less than three inches; 

2. Load all haul trucks such that at no time shall the highest point of the bulk 

material be higher than the sides, front, and back of a cargo container area; 

3. Prevent spillage or loss of bulk material from holes or other openings in the cargo 

compartment’s floor, sides, and/or tailgate(s); and 

4. When crossing and/or accessing a paved area accessible to the public, install, 

maintain, and use a suitable trackout control device that controls and prevents 

trackout and/or removes particulate matter from tires and the exterior surfaces of 

haul trucks and/or motor vehicles that traverse the Site. 

L. Demolition; Emission Mitigation 

To the extent Development Activity includes demolition activities, implement all of the 

following measures: 

 1. Apply water to demolition debris immediately following demolition activity; and 

2. Apply water to all disturbed soil surfaces to establish a crust and to prevent wind 

erosion. 

M. Weed Abatement; Emission Mitigation 

To the extent Earthmoving for a particular project includes weed abatement activity, 

implement all of the following control measures: 

 1. Before weed abatement by discing or blading occurs, apply water; 

 2. While weed abatement by discing or blading is occurring, apply water; and 

 3. After weed abatement by discing or blading occurs, pave, apply gravel, apply 

water, apply a suitable dust suppressant other than water, or establish vegetative 

ground cover. 

 

N. Blasting; Emission Mitigation 

All of the following control measures shall be implemented for blasting operations at a 

Site: 

 1. In wind gusts above 25 miles per hour, discontinue/cease blasting; and 

 2. Pre-water and maintain surface soils in a stabilized condition where support 

equipment and vehicles will operate. 

O. Subcontractor Registration Verification 

Assure that any subcontractors engaged in earthmoving activity on the Site have 

registered with Pinal County Air Quality as a subcontractor. 

[ Adopted June 3, 2009, effective August 26, 2009]
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4-7-234. Nonattainment-Area Dust Permit Program; General Provisions 

A. Permittee's Universal Obligations 

 A permittee under this Article shall be bound to comply with: 

 1. Applicable objective and work practice standards, 

 2. The commitments in a dust control plan submitted in support of the application, 

 3. The application acknowledgments required for a particular permit, and 

 4. The obligations, standards, and commitments in a permit. 

B. Permit Types 

 1. Site Permits 

 2. Nonattainment Area Block Permits 

3. Any Site subject to a permit requirement under this rule shall not require an 

additional registration under §4-3-080, the existing county-wide dust registration 

program. 

C. Application Review and Approval; Dust Control Plan Merger; Limited Effect of 

Approval 

1. Following submittal of a complete application under this Article, including 

payment of any necessary fee, the Control Officer shall within 10 working days 

approve, disapprove, or conditionally approve the permit application, in 

accordance with the requirements of this Article. 

2. Upon approval of any permit under this Article, the provisions of any dust 

control plan submitted as part of the application shall be merged as part of the 

permit, and any commitments in the dust control plan shall constitute enforceable 

requirements under the permit. 

3. Approval of a permit under this Article shall not excuse, or act as a shield with 

respect to, a violation of any requirement or limitation under these rules, 

including the provisions of this Article. 

 

D. Fees 

 Issuance of every permit shall be subject to payment of a fee as specified in Appendix C. 

1. Construction Permits shall be assessed a fee based on project area and the fee 

specified in earthmoving Category A. 

2. Block permits shall be assessed a fee based on Appendix C, earthmoving 

Category D. 
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 3. Permit transfers shall be approved without a fee. 

4. Permit revisions shall be assessed a fee based on the time required to process the 

revision application, with a minimum billing of one hour, and a maximum 

revision fee of $1000.00. 

 5. Late-filed applications are subject to the late filing fee specified in Appendix C. 

 6. Fee waivers are not allowed. 

E. Permit Duration 

 All permits shall have a one-year permit term. 

F. Permit Revisions 

A permittee may request revision of a permit or a transfer of the permit by filing an 

amended application. A transfer request shall bear the signatures of authorized 

representatives for both the transferor and the transferee, and shall further properly 

identify the transferee. 

G. Renewals 

Should a construction project last longer than the term of a permit, the permittee shall reapply for a Dust Control Permit at least 14 calendar days prior to the expiration date of 

the original permit term. For good cause show, the Control Officer may extend that 

renewal application deadline. Provided the applicant has a rational system for the 

completion status of individual parcels within a project, a single permit renewal may 

cover derivative parcels even though they are no longer contiguous. The renewal fee 

shall be based on the un-completed area of the project. 

H. Right of entry and inspection. 

Subject to the requirements of 49-471.03, any Site covered by a permit issued pursuant to 

this Article is subject to inspection without prior notice by the Control Officer. 

I. Application signatures. 

Every application shall be signed by an individual, and that signature shall constitute a 

personal representation that the signer has authority to commit the named permit 

applicant ("Permittee") to comply with the provisions of this Article. 

[ Adopted June 3, 2009, effective August 26, 2009]

4-7-238. Nonattainment Area Site Permits 

A. Applicability 

1. Onset. Before Development Activity begins on a Site that will involve a 

disturbance of an aggregate area of more than 0.1 acres, the Owner and/or 

Operator or someone with privity to the Owner and/or Operator shall apply for 

and obtain a Site Permit from the Control Officer. 

2. Duration/Termination. The Site Permit shall be maintained until all of the 

following occur: 

 a. Development Activity has ceased. 
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 b. All disturbed portions of the Site have been stabilized. 

 c. Closure of the Site Permit in accord with this rule. 

B. Application Requirements 

 A Site Permit application shall include each of: 

 1. Application coversheet 

The applicant shall present an application on a form approved by the Control 

Officer, and shall include all essential identification information as specified on 

that form, including a proper legal identification of the applicant and the property 

owner, and the assessor's parcel number(s) for the project. A separate application 

is required for each Site location not contiguous to the location on the original 

application form. 

 2. Plot Plan or Site Plan 

Each application shall include a plot plan with linear dimensions in feet. The 

plot plan must be on 8-1/2 by 11 inch paper, and may be on one or more sheets. 

The plan should identify the assessor's parcel number(s), the street address(es), 

the direction north, indicate the areas to be disturbed, and include a calculation of 

the area to be disturbed. The plan should show: 

 a. Entire project site/facility boundaries, 

 b. Acres to be disturbed with linear dimensions, 

 c. Nearest public roads, 

 d. North arrow, and 

 e. Planned exit locations onto paved areas accessible to the public. 

 3. Identification of surface-disturbing Activities 

The Site Permit Application shall separately identify all activities that may cause 

a surface disturbance, specifically including planned earthmoving activities and 

other planned activities that may cause a disturbed surface. 

a. Non-earthmoving Activities. The Site Permit application shall identify 

planned non-earthmoving activity, including any of: 

 i. Vehicle traffic 

 ii. Equipment traffic 

 iii. Parking 

 iv. Material storage and handling 

 v. Other activities. 

b. Earthmoving Activities. The Site Permit application shall identify 

planned earthmoving activity, including any of: 

 i. Primary mass grading operations 

 ii. Excavations for new footings, pads and concrete work 

 iii. Grubbing existing foundations, slabs or structures 

 iv. Installation of underground utilities 

 v. Landscaping 

 vi. Other earthmoving activities as defined in §4-7-210. 

 
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4. Site Dust Control Plan. 

The applicant shall include in the application a Site Dust Control Plan, explaining 

the mitigation measures that will be used to control dust from every covered 

activity to be conducted on the Site. To be approvable under §4-7-234.C, the 

Dust Control Plan must explain how the Permittee will achieve compliance with 

each relevant objective standard in §4-7-226 and each relevant work practice 

standard in §4-7-230. At a minimum, the Site Dust Control Plan must address 

each of the following issues, and for each of the controls required under 

subparagraphs a. through h., must both designate all required measures as 

primary control measures and must additionally designate at least one 

contingency control measure: 

 a. Indicate how access to the Site will be controlled. 

b. Indicate whether the project will require a trackout control system. 

Whether or not a trackout control system is required, explain how 

trackout will be controlled at each of the access points. 

c. For every identified earthmoving activity, explain how dust will be 

controlled by actions taken prior to or during that activity. 

d. Apart from earthmoving, explain how the Permittee will establish and 

maintain stabilization of roadways, and areas used for traffic, parking, 

and the handling and storage of materials. 

e. If the applicant proposes to achieve stabilization by limiting speeds and 

traffic volume, explain how those limits will be enforced. 

f. Explain how, once earthmoving operations are completed, affected areas 

will be stabilized. 

g. Explain how areas disturbed by non-earthmoving activities will be 

stabilized. 

h. If stabilization will depend upon restricting access or preventing trespass, 

explain how that will be achieved. 

i. If dust mitigation efforts will involve use of dust suppressants, identify 

the product, include copies of MSDS sheets, and define in the plan 

details of the utilization in accord with the manufacturer's 

recommendations, including the method, frequency and intensity of 

application; the type, number and capacity of application equipment; 

and information on environmental impacts and approvals or certifications 

related to appropriate safe use for ground application. 

j. Define how often records of the volume of water- or suppressant-usage 

will be recorded. 

k. Define how frequently property-line opacity observations will be 

conducted and corresponding records recorded. 

l. Define how frequently activity-linked opacity observations will be 

conducted and corresponding records recorded. 

m. Define how frequently stabilization observations will be conducted and 

corresponding records recorded. 

n. Define how frequently trackout inspections will be conducted and 

corresponding records recorded. 
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 5. Phased Close-out Plan 

A Site Permit applicant may propose, as an element of the Site Dust Control 

Plan, a tracking system to define which individual parcels within a PAD or 

subdivision have qualified for Permit Closeout with respect to that parcel. 

Subject to the approval of the Control Officer, the tracking system proposal may 

include an electronic spreadsheet and linked electronic map maintained at the 

PAD or subdivision site. Closeout with respect to any parcel cannot take effect 

before the Permittee provides notice to the Control Officer regarding that parcel. 

Implementation of any such phased plan requires the express approval of the 

Control Officer. 

C. Permittee's Obligations 

1. Application Acknowledgments. By signing an application, the Permittee 

acknowledges obligations to, and liability for failure to: 

a. Assure that any earthmoving activity on the Site is covered by the 

Permit; 

 b. With respect to the Site: 

i. Comply with or cause compliance with objective standards of 

§4-7-226. 

ii. Comply with or cause compliance with obligatory work practice 

standards of §4-7-230. 

iii. Comply with or cause compliance with commitments in the dust 

management plan submitted in support of the Permit application. 

2. Permit must be available on-site. A complete copy of the Site Permit, including 

the dust control plan, shall be kept on the project at all times that Construction 

Activities occur and shall be made available upon request of the Control Officer. 

3. Recordkeeping. On any day when disturbed surfaces remain on the Site and any 

earthmoving or construction activity occurs, the Permittee shall maintain daily 

logs showing: 

 a. Records verifying integrity of entrance/exit definitions. 

 b. Records of trackout compliance inspections. 

c. Water/suppressant truck hours of operation and water or suppressant 

application rates. Permittee may use whatever metrics will reasonably 

reflect actual application rates. 

 d. Records of opacity observations, including notation of methods utilized. 

e. Records of location and results of surface stabilization assessments, 

including notation of methods utilized. 

 f. Compliance with the dust control plan. 

4. Basic Dust Control Training Requirement. No later than December 31, 2008, a 

site superintendent or other designated on-site representative of the permit holder 

and water truck and water pull drivers for each Site shall have successfully 

completed a Control-Officer-approved Basic Dust Control Training Class. 
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5. Dust Control Coordinator Requirement. Any Site, or any contiguous 

combination of Sites under common control, having five acres or more of 

disturbed surface area subject to a Permit requirement shall, at all times during 

earthmoving activity operations related to the purposes for which a Site Permit is 

required, have on-site at least one individual qualified under a Control-Officerapproved Dust Control Coordinator training program. 

D. Permit Closeout 

1. Site-wide Project Closure; Closure of the Obligations of the Owner and/or 

Operator. 

An Owner and/or Operator may attain a project-wide closeout ("project closure") 

by obtaining from the Control Officer a written Approval of Certificate of Project 

Completion based upon a showing of final stabilization following completion of 

all Development Activity. 

 2. Site-wide Project Closure; Closure of Permittee's Obligation. 

A Permittee may terminate his liability under this Article by obtaining from the 

Control Officer a written Approval of Certificate of Project Completion, based 

upon the contractor's showing of: 

a. Final stabilization following completion of contracted project-wide 

Development Activity; 

b. Other equitable grounds (i.e. Termination of contractor's involvement 

with project). 

 3. Phased Closure. 

An Owner and/or Operator and a Permittee may terminate liability and obligation 

under this Article with respect to a specific lot or parcel within a development, by 

complying with the terms of a Control-Officer-approved phased closure plan. 

[ Adopted June 3, 2009, effective August 26, 2009]

4-7-242. Nonattainment Area Block Permits 

A. Applicability 

1. Nonattainment Area Block Permits shall only be available for earthmoving 

activity associated with: 

 a. Maintenance of existing underground or above-ground lines; 

b. Effecting end-user connections, including but not limited to water 

connections, sewer connections, natural gas connections, electrical power 

connections, and communications connections; 

 c. Underground utility line extensions not exceeding 500' in length; and 

 d. Overhead utility line extensions. 

 2. Nonattainment Area Block Permits shall only be available to: 

 a. Political subdivisions; and 
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b. Public Utility Corporations regulated by the Arizona Corporation 

Commission. 

B. Application Requirements 

 A Nonattainment Area Block Permit application shall include each of: 

 1. Application coversheet 

The applicant shall present an application on a form approved by the Control 

Officer, and shall include all identification information as specified on that form, 

including a proper legal identification of the applicant. 

 2. Plot Plan or Site Plan - Not required. 

 3. Identification of surface-disturbing activities 

The Block Permit Application shall acknowledge that applicability is limited to 

installation of underground utilities and any associated landscaping. 

 4. Permit applicability form 

 Not required. 

 5. Block Permit dust control plan. 

The applicant shall include in the application a Block Permit Dust Control Plan, 

explaining the mitigation measures that will be used to control dust from every 

covered activity to be conducted under the Block Permit. To be approvable 

under §4-7-234.C, the Block Permit Dust Control Plan must explain how the 

Permittee will achieve compliance with each relevant objective standard in §4-7-

226 and each relevant work practice standard in §4-7-230. At a minimum, the 

Block Permit Dust Control Plan must address each of the following issues, and 

for each of the controls required under subparagraphs a. through h., must both 

designate all required measures as primary control measures and must 

additionally designate at least one contingency control measure: 

 a. Indicate how access to the Site will be controlled. 

b. Indicate whether the project will require a trackout control system. 

Whether or not a trackout control system is required, explain how 

trackout will be controlled at each of the access points. 

c. For every identified earthmoving activity, explain how dust will be 

controlled by actions taken prior to or during that activity. 

d. Apart from earthmoving, explain how the Permittee will establish and 

maintain stabilization of roadways, and areas used for traffic, parking, 

and the handling and storage of materials. 

e. If the applicant proposes to achieve stabilization by limiting speeds and 

traffic volume, explain how those limits will be enforced. 

f. Explain how, once earthmoving operations are completed, affected areas 

will be stabilized. 

g. Explain how areas disturbed by non-earthmoving activities will be 

stabilized. 

h. If stabilization will depend upon restricting access or preventing trespass, 

explain how that will be achieved. 
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i. If dust mitigation efforts will involve use of dust suppressants, identify 

the product, include copies of MSDS sheets, and define in the plan 

details of the utilization in accord with the manufacturer's 

recommendations, including the method, frequency and intensity of 

application; the type, number and capacity of application equipment; 

and information on environmental impacts and approvals or certifications 

related to appropriate safe use for ground application. 

j. Define how often records of the volume of water- or suppressant-usage 

will be recorded. 

k. Define how frequently property-line opacity observations will be 

conducted and corresponding records recorded. 

l. Define how frequently activity-linked opacity observations will be 

conducted and corresponding records recorded. 

m. Define how frequently stabilization observations will be conducted and 

corresponding records recorded. 

n. Define how frequently trackout inspections will be conducted and 

corresponding records recorded. 

C. Block Permittee's Obligations 

1. Application Acknowledgments. By signing an application, the Block Permittee 

acknowledges an obligation to: 

a. Assure that any earthmoving activity on the Site conducted by the 

Permittee is covered by an Block Permit; 

 b. With respect to every Site: 

i. Comply with objective standards of §4-7-226, including the 

post-operation stabilization requirement. 

 ii. Comply with obligatory work practice standards of §4-7-230. 

iii. Comply with commitments in the dust management plan 

submitted in support of the Block Permit application. 

2. The Block Permittee shall, for any project that will disturb more than 0.1 acres, 

provide the Control Officer with notice of the start and completion of each 

project conducted under the Block Permit. The notice shall be provided in a 

format approved by the Control Officer. 

3. Permit must be available on-site. For any project for which notification is 

required, a complete copy of the Block Permit, including the Block Permit Dust 

Control Plan, shall be available on every project Site at all times that 

earthmoving activities occur and made available upon request of the Control 

Officer. 

4. Permittee responsible for compliance. The permittee is responsible for ensuring 

that all Persons abide by the conditions of the Block Permit and these regulations 

such that the Site remains in compliance with the Block Permit. 
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 5. Recordkeeping 

Unless an alternative frequency is presented in a dust control plan and approved 

in a permit, on any day when earthmoving activity occurs the Permittee shall 

maintain daily logs showing: 

a. Water/suppressant truck hours of operation and water or suppressant 

application rates. Permittee may use whatever metrics reasonably reflect 

application rates. 

 b. Records of opacity observations, including notation of methods utilized. 

c. Records of location and results of post-operation surface stabilization 

assessments, including notation of methods utilized. 

 d. Compliance with Block Permit dust control plan. 

6. Basic Dust Control Training Requirement. A site superintendent or other 

designated on-site representative of the Block Permit holder and water truck and 

water pull drivers for each Site that will involve disturbance of more than 0.1 

acres shall have successfully completed a Control-Officer-approved Basic Dust 

Control Training Class. 

D. Permit Closeout 

 Not applicable. 

[ Adopted June 3, 2009, effective August 26, 2009]

4-7-246. Recordkeeping and Records Retention 

A. Requirement to furnish records upon request. Upon verbal or written request by 

the Control Officer, the log or the records and supporting documentation required 

under this Article shall be provided as soon as possible but no later than 48 hours, 

excluding weekends. If the Control Officer is at the Site where requested records 

are kept, records shall be provided without delay. 

B. Records Retention. Any person subject to a record-keeping requirement shall 

retain copies of approved Dust Control Plans, control measures implementation 

records, and all supporting documentation for at least six months following the 

termination of the dust-generating operation and for at least two years from the 

date such records were initiated. 

[ Adopted June 3, 2009, effective August 26, 2009]

ARTICLE 8. NONATTAINMENT AREA RULES, REQUIREMENT FOR 

STABILIZATION OF DISTURBED AREAS AT VACANT LOTS 

4-8-260. Stabilization of Disturbed Areas at Vacant Lots; Applicability 

A. Geographic Applicability. 

The "affected area" under this rule includes the Pinal-County-portion of the Phoenix 

Planning Area Serious PM10 nonattainment Area, identified as Township 1 North, Range 8 

East, Gila & Salt River Base and Meridian. 
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B. Affected Parcels; Vacant Lots. 

1. For purposes of this rule, "vacant lot" means a parcel of land on which there are 

no approved or permitted permanent or temporary buildings or structures. 

2. For purposes of this rule, where an owner holds a non-vacant lot, "vacant lot" 

does not include a contiguous parcel or parcels adjoining that non-vacant lot, but 

the exemption applies only if the parcels are subject to common legal or 

equitable ownership and the parcels are used in fact as a single lot. 

3. For purposes of this rule, a "vacant lot" does not include the site of a disturbed 

surface area that is subject to control of dust generating operations pursuant to a 

dust registration issued by the Control Officer pursuant to Chapter 4, Article 3 of 

these rules. 

4. For purposes of this rule, a "vacant lot" does not include the site of a disturbed 

surface area that is subject to an industrial permit issued by the Control Officer 

pursuant to Chapter 3 of these rules. 

C. Affected Areas Within Vacant Lots; Disturbed Surfaces 

1. For purposes of this rule, "disturbed surface" means a portion of the earth's 

surface or material placed on the earth's surface that has been physically moved, 

uncovered, destabilized or otherwise modified from its undisturbed native 

condition if the potential for the emission of fugitive dust is meaningfully 

increased by the movement, destabilization or modification. 

 2. For purposes of this rule, "disturbed surface" does not include: 

a. Any area that is subject to a control of dust generating operations 

pursuant to dust registration issued by the Control Officer pursuant to 

Chapter 4, Article 3 of these rules. 

 b. Any area that is disturbed as a result of normal farm cultural practice. 

 c. Any area while the activity causing the disturbance is still proceeding. 

[Adopted effective September 10, 2008.] 

4-8-270. Stabilization Notice; Right of Entry; Recoupment of Costs; Right to Appeal 

A. If the Control Officer finds that an unpaved disturbed surface at a vacant lot subject to this 

Article requires stabilization, the Control Officer may provide a written notice to the owner 

or the owner's agent that the unpaved disturbed surface is required to be stabilized. 

B. The notice shall: 

 1. Be given not less than thirty days before the date set for compliance; 

 2. Recite the factual basis for the notice; 
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 3. Include a legal description of the property; 

4. Inform the owner that if he does not stabilize the lot prior to the compliance date, 

the county will have authority to enter the lot to stabilize the disturbed surface at 

the expense of the owner; 

5. Include the proposed method of stabilization and the estimated cost to the county 

for the stabilization if the owner does not comply; 

6. Inform the owner that the notice constitutes an appealable agency action, and that 

the owner has a right of administrative appeal pursuant to A.R.S. §49-471.15. 

C. The notice shall be either personally served or mailed by certified mail to the owner's 

statutory agent, to the owner at the owner's last known address or to the address to which 

the tax bill for the property was last mailed. For purposes of establishing a compliance date 

and triggering an appeal period, mailed notice shall be effective upon mailing. 

D. If the owner fails to either stabilize the disturbed area or appeal the notice, the County shall 

have authority to enter the lot, effect stabilization, and recover the costs up to the amount of 

the estimate provided to the owner. 

[Adopted effective September 10, 2008.] 

4-8-280. Deferred enforcement date 

 The Control Officer shall commence enforcement of the requirements of this Article no 

sooner than October 1, 2008. 

[Adopted effective September 10, 2008.] 

ARTICLE 9. TEST METHODS 

4-9-300. Test Method; Threshold Friction Velocity 

A. Threshold friction velocity ("TFV") constitutes a measure of surface erodability. 

Assessment of TFV under this rule shall utilize a field-sieving procedure and a 

mathematical adjustment based on a quantitative assessment of non-erodible geologic 

elements that may be present. 

B. Step 1. Obtain and stack a set of sieves with the following openings: 

 1. 4 millimeters (mm); Tyler Sieve No. 5; ASTM 11 Sieve No. 5. 

 2. 2 mm; Tyler Sieve No. 9; ASTM 11 Sieve No. 10. 

 3. 1 mm; Tyler Sieve No. 16; ASTM 11 Sieve No. 18. 

 4. 0.5 mm; Tyler Sieve No. 32; ASTM 11 Sieve No. 35. 

 5. 0.25 mm; Tyler Sieve No. 60; ASTM 11 Sieve No. 60. 

 6. A collector pan. 

 7. A cover. 

C. Step 2. Stack the sieves and pan in size-order, with the largest openings at the top and the 

pan at the bottom. Collect a sample of loose surface material from an area at least 30 

centimeters (cm) by 30 cm to a depth of approximately 1 cm using a brush and dustpan or 
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other similar device. Only collect soil samples from dry surfaces (i.e. when the surface is 

not damp to the touch). Remove any rocks larger than 1 cm in diameter from the sample. 

Carefully pour the ample into the top sieve (4 mm opening), minimizing escape of particles 

from the sample. Cover the sieve-stack with the lid. 

D. Step 3. Manually swing the sieve-stack in a broad, circular pattern in a horizontal plane. 

Move the sieve-stack at a speed just necessary to audibly verify some relative horizontal 

motion of the sample within the sieve-stack. Complete twenty circular sweeps, ten 

clockwise and ten counter-clockwise. Remove the lid and un-stack the sieves in decreasing 

size-order. As each sieve is removed, examine the screen for loose particles. If loose 

particles have not been sifted to the finest sieve through which they can pass, reassemble 

the sieve-stack and cover and rotate the stack through an additional ten sweeps, five 

clockwise and five counter-clockwise. After disassembling the sieve-stack, slightly tilt and 

gently tap each sieve and the collector pan so that the material collects along one side. In 

so doing, minimize escape of particles into the air. 

E. Step 5. Line up the sieves and the pan and visually inspect the collected material to assess 

the relative volumes of material in each. If visual inspection is not sufficient to distinguish 

the relative volumes, pour the respective contents into a graduated cylinder to precisely 

measure the volume in each sieve and pan. 

F. Step 6. Identify the sieve or pan with the greatest volumetric catch, and define an initial 

TFV according to the following correlation: 4 mm sieve - 135 cm/sec.; 2 mm sieve - 100 

cm/sec.; 1 mm sieve - 76 cm/sec.; 0.5 mm sieve - 58 cm/sec.; 0.25 mm sieve - 43 cm/sec.; 

collector pan - 30 cm./sec. 

G. Step 7. Quantify an average TFV for the affected area. Repeat steps 1 through 6 for two 

other respresentative sites within the affected area, and arithmetically average the three 

TFV values to define an average initial TFV. 

H. Step 8. Adjust the TFV to correct for non-erodible elements. Non-erodible elements are 

distinct elements in the random portion of the overall conditions of the affected area that 

are larger than 1 cm in diameter, remain firmly in place during a wind episode, and inhibit 

soil loss by consuming part of the shear stress of the wind. Non-erodible elements include 

stones and bulk surface material but do not include flat or standing vegetation. 

I. Step 9. Select and mark off a 1 meter by 1 meter survey area that represents the general 

rock distribution on the surface. For these purposes, non-erodible, non-vegetative matter 

qualifies as "rock." Without moving any of the surface material, visually assess the surface 

to determine whether rocks larger than 1 cm (3/8 inch) are present. If the rocks are of 

relatively consistent dimension, count the number of rocks in the survey area. If the size of 

the rocks differs substantially, define small, medium and large size categories and count the 

number of rocks in each category. 

J. Step 10. Remove one or two representative rocks from each size category (if necessary), 

and measure the length and width of each. Calculate an area for each size category (if 

necessary) based on the measured length and width. 
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K. Step 11. Calculate an aggregate area for each size category (if necessary), based on the 

number of rocks and measured representative individual rock-area. If multiple size 

categories were defined, total the aggregate areas for the categories. Divide the calculated 

aggregate area by two, and then divide that product by the area of the original sample area 

to calculate a %-coverage. For example, within a 1-meter (100 cm) square sample area, 

250 rocks with a 1 cm x 1.5 cm length/width produces a coverage of 250 x 1 x 1.5 / 2 /(100 

x 100) = 1.88% coverage. 

L. Step 12. Quantify an average coverage for non-erodible elements within the overall 

affected area. Repeat steps 8 through 11 for two other sites within the affected area, and 

arithmetically average the three coverage values to define an average non-erodible area 

coverage. 

M. Step 13. Based on the calculated average coverage by non-erodible elements, select a TFV 

correction factor according to the following correlation: non-erodible element coverage > 

10% - correction factor = 5; non-erodible element coverage < 10% but > 5% - correction 

factor = 3; non-erodible element coverage < 5% but > 1% - correction factor = 2; nonerodible element coverage < 1% - correction factor = 1. 

N. Step 14. Using the initial average TFV value from Step 7, multiply by the TFV correction 

factor from Step 13 to calculate a representative TFV for the site. 

[Adopted effective September 10, 2008.] 

4-9-320. Test Methods for Stabilization For Unpaved Roads and Unpaved Parking Lots 

A. For Unpaved Roads and Unpaved Parking Lots 

1. Silt Content Test Method. The purpose of this test method is to estimate the silt 

content of the trafficked parts of unpaved roads and unpaved parking lots. The 

higher the silt content, the more fine dust particles that are released when cars 

and trucks drive on unpaved roads and unpaved parking lots. 

 a. Equipment: 

i. A set of sieves with the following openings: 4 millimeters (mm), 

2 mm, 1mm, 0.5 mm and 0.25 mm (or a set of 

standard/commonly available sieves), a lid, and a collector pan. 

ii. A small whisk broom or paintbrush with stiff bristles and 

dustpan 1 ft. in width (The broom/brush should preferably have 

one, thin row of bristles no longer than 1.5 inches in length). 

 iii. A spatula without holes. 

iv. A small scale with half-ounce increments (e.g. postal/package 

scale). 

 v. A shallow, lightweight container (e.g. plastic storage container). 

 vi. A sturdy cardboard box or other rigid object with a level surface. 

 vii. A basic calculator. 

viii. Cloth gloves (optional for handling metal sieves on hot, sunny 

days). 

 ix. Sealable plastic bags (if sending samples to a laboratory). 

 x. A pencil/pen and paper. 
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b. Step 1 [-Test Site Selection; Sample Collection]: Look for a routinely 

traveled surface, as evidenced by tire tracks. [Only collect samples from 

surfaces that are not damp due to precipitation or dew. This statement is 

not meant to be a standard in itself for dampness where watering is being 

used as a control measure. It is only intended to ensure that surface 

testing is done in a representative manner.] Use caution when taking 

samples to ensure personal safety with respect to passing vehicles. 

Gently press the edge of a dustpan (1 foot in width) into the surface four 

times to mark an area that is 1 square foot. Collect a sample of loose 

surface material using a whiskbroom or brush and slowly sweep the 

material into the dustpan, minimizing escape of dust particles. Use a 

spatula to lift heavier elements such as gravel. Only collect dirt/gravel to 

an approximate depth of 3/8 inch or 1 cm in the 1 square foot area. If you 

reach a hard, underlying subsurface that is < 3/8 inch in depth, do not 

continue collecting the sample by digging into the hard surface. In other 

words, you are only collecting a surface sample of loose material down 

to 1 cm. In order to confirm that samples are collected to 1 cm in depth, 

a wooden dowel or other similar narrow object at least one foot in length 

can be laid horizontally across the survey area while a metric ruler is 

held perpendicular to the dowel. 

- At this point, you can choose to place the sample collected into a 

plastic bag or container and take it to an independent laboratory 

for silt content analysis. A reference to the procedure the 

laboratory is required to follow is at the end of this section. 

c. Step 2 [- Sample Weighing]: Place a scale on a level surface. Place a 

lightweight container on the scale. Zero the scale with the weight of the 

empty container on it. Transfer the entire sample collected in the 

dustpan to the container, minimizing escape of dust particles. Weigh the 

sample and record its weight. 

d. Step 3 [- Equipment Configuration]: Stack a set of sieves in order 

according to the size openings specified above, beginning with the 

largest size opening (4 mm) at the top. Place a collector pan underneath 

the bottom (0.25 mm) sieve. 

e. Step 4 [- Sample Processing #1]: Carefully pour the sample into the 

sieve stack, minimizing escape of dust particles by slowly brushing 

material into the stack with a whiskbroom or brush. (On windy days, use 

the trunk or door of a car as a wind barricade.) Cover the stack with a 

lid. Lift up the sieve stack and shake it vigorously up, down and 

sideways for at least 1 minute. 

f. Step 5 [- Sample Processing #2]: Remove the lid from the stack and 

disassemble each sieve separately, beginning with the top sieve. As you 

remove each sieve, examine it to make sure that all of the material has 

been sifted to the finest sieve through which it can pass (e.g., material in 

each sieve [besides the top sieve that captures a range of larger elements] 
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should look the same size). If this is not the case, re-stack the sieves and 

collector pan, cover the stack with the lid, and shake it again for at least 1 

minute. (You only need to reassemble the sieve(s) that contain material, 

which requires further sifting.) 

g. Step 6 [- Weighing Collector Pan Material]: After disassembling the 

sieves and collector pan, slowly sweep the material from the collector 

pan into the empty container originally used to collect and weigh the 

entire sample. Take care to minimize escape of dust particles. You do 

not need to do anything with material captured in the sieves; only the 

collector pan. Weigh the container with the material from the collector 

pan and record its weight. 

h. Step 7 [- Silt Loading and Silt Content Calculation]: If the source is an 

unpaved road, multiply the resulting weight by 0.38. If the source is an 

unpaved parking lot, multiply the resulting weight by 0.55. The resulting 

number is the estimated silt loading. Then, divide by the total weight of 

the sample you recorded earlier in Step 2 and multiply by 100 to estimate 

the percent silt content. 

i. Step 8 [- Characterization Across Entire Site]: Select another two 

routinely traveled portions of the unpaved road or unpaved parking lot 

and repeat this test method. Once you have calculated the silt loading 

and percent silt content of the 3 samples collected, average your results 

together. 

j. Step 9: Examine Results. If the average silt loading is less than 0.33 

oz/ft2, the surface is STABLE. If the average silt loading is greater than 

or equal to 0.33 oz/ft2, then proceed to examine the average percent silt 

content. If the source is an unpaved road and the average percent silt 

content is 6% or less, the surface is STABLE. If the source is an 

unpaved parking lot and the average percent silt content is 8% or less, the 

surface is STABLE. If your field test results are within 2% of the 

standard (for example, 4%–8% silt content on an unpaved road), it is 

recommended that you collect 3 additional samples from the source 

according to Step 1 and take them to an independent laboratory for silt 

content analysis. 

k. Independent Laboratory Analysis: You may choose to collect 3 samples 

from the source, according to Step 1 and send them to an independent 

laboratory for silt content analysis rather than conduct the sieve field 

procedure. If so, the test method the laboratory is required to use is: 

 - U.S. Environmental Protection Agency (1995), “Procedures for 

Laboratory Analysis of Surface/Bulk Dust Loading Samples”, 

(AP-42 Fifth Edition, Volume I, Appendix C.2.3 “Silt 

Analysis”), Office of Air Quality Planning and Standards, 

Research Triangle Park, North Carolina. 
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B. Stabilization Limitations for Open Areas and Vacant Lots: The test methods described 

below shall be used to determine whether an open area or a vacant lot has a stabilized 

surface. Should a disturbed open area or vacant lot contain more than one type of 

disturbance, soil, vegetation, or other characteristics, which are visibly distinguishable, 

test each representative surface separately for stability, in an area that represents a 

random portion of the overall disturbed conditions of the site, according to the 

appropriate test methods described below, and include or eliminate it from the total size 

assessment of disturbed surface area(s) depending upon test method results. 

 1. Visible Crust Determination [- The "Drop Ball Test"]. 

a. [Appropriate Testing Conditions] Where a visible crust exists, drop a 

steel ball with a diameter of 15.9 millimeters (0.625 inches) and a mass 

ranging from 16-17 grams (0.56-0.60 ounce) from a distance of 30 

centimeters (one foot) directly above (at a 90° angle perpendicular to) 

the soil surface. If blowsand is present, clear the blowsand from the 

surfaces on which Drop Ball Test is conducted. Blowsand is defined as 

thin deposits of loose uncombined grains covering less than 50% of a 

vacant lot which have not originated from the representative vacant lot 

surface being tested. If material covers a visible crust, which is not 

blowsand, apply the Threshold Friction Velocity determination of §B.2 

of this rule to the loose material to determine whether the surface is 

stabilized. 

b. [Definition of Sufficient Crust] A sufficient crust is defined under the 

following conditions: once a ball has been dropped according to the 

Appropriate Testing Conditions of §B.1.a, the ball does not sink into the 

surface, so that it is partially or fully surrounded by loose grains and, 

upon removing the ball, the surface upon which it fell has not been 

pulverized, so that loose grains are visible. 

c. [Characterization of Crust Across Entire Site] Drop the ball three times 

within a survey area that measures 1 foot by 1 foot and that represents a 

random portion of the overall disturbed conditions at the site. The 

survey area shall be considered to have passed the Visible Crust 

Determination Test if at least two out of the three times that the ball was 

dropped, the results met the Definition of Sufficient Crust in §B.1.b. 

Select at least two other survey areas that represent a random portion of 

the overall disturbed conditions of the site, and repeat this procedure. If 

the results meet the Definition of Sufficient Crust in §B.1.b for all of the 

survey areas tested, then the site shall be considered to have passed the 

Visible Crust Determination Test and shall be considered sufficiently 

crusted. 

d. [Characterization of Crust Across Entire Site] At any given site, the 

existence of a sufficient crust covering one portion of the site may not 

represent the existence or protectiveness of a crust on another portion of 

the site. Repeat the visible crust test as often as necessary on each 
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random portion of the overall conditions of the site for an accurate 

measurement. 

 2. Determination of Threshold Friction Velocity (TFV): For disturbed surface areas 

that are not crusted or vegetated, determine threshold friction velocity (TFV) 

according to the following sieving field procedure (based on a 1952 laboratory 

procedure published by W. S. Chepil). 

a. [Equipment & Procedure] Obtain and stack a set of sieves with the 

following openings: 4 millimeters (mm), 2 mm, 1 mm, 0.5 mm, and 0.25 

mm or obtain and stack a set of standard/commonly available sieves. 

Place the sieves in order according to size openings, beginning with the 

largest size opening at the top. Place a collector pan underneath the 

bottom (0.25 mm) sieve. Collect a sample of loose surface material from 

an area at least 30 cm by 30 cm in size to a depth of approximately 1 cm 

using a brush and dustpan or other similar device. Only collect soil 

samples from dry surfaces (i.e. when the surface is not damp to the 

touch). Remove any rocks larger than 1 cm in diameter from the sample. 

Pour the sample into the top sieve (4 mm opening) and cover the 

sieve/collector pan unit with a lid. Minimize escape of particles into the 

air when transferring surface soil into the sieve/collector pan unit. Move 

the covered sieve/collector pan unit by hand using a broad, circular arm 

motion in the horizontal plane. Complete twenty circular arm 

movements, ten clockwise and ten counter-clockwise, at a speed just 

necessary to achieve some relative horizontal motion between the sieves 

and the particles. Remove the lid from the sieve/collector pan unit and 

disassemble each sieve separately beginning with the largest sieve. As 

each sieve is removed, examine it for loose particles. If loose particles 

have not been sifted to the finest sieve through which they can pass, 

reassemble and cover the sieve/collector pan unit and gently rotate it an 

additional ten times. After disassembling the sieve/collector pan unit, 

slightly tilt and gently tap each sieve and the collector pan so that 

material aligns along one side. In doing so, minimize escape of particles 

into the air. Line up the sieves and collector pan in a row and visibly 

inspect the relative quantities of catch in order to determine which sieve 

(or whether the collector pan) contains the greatest volume of material. 

If a visual determination of relative volumes of catch among sieves is 

difficult, use a graduated cylinder to measure the volume. Estimate TFV 

for the sieve catch with the greatest volume using Table 1, which 

provides a correlation between sieve opening size and TFV. 

Table 1. Determination of Threshold Friction Velocity 

Tyler Sieve No. ASTM 11 Sieve No. Opening (mm) TFV (cm/s) 

 5 5 5 135 

 9 10 2 100 

 16 18 1 76 

 32 35 0.5 58 

 60 60 0.25 43 

 Collector Pan - - 30 

 
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b. [Characterization of TFV Across Entire Site] Collect at least three soil 

samples which represent random portions of the over-all conditions of 

the site, repeat the above TFV test method for each sample and average 

the resulting TFVs together to determine the TFV uncorrected for nonerodible elements. Non-erodible elements are distinct elements, in the 

random portion of the overall conditions of the site, that are larger than 1 

cm in diameter, remain firmly in place during a wind episode, and inhibit 

soil loss by consuming part of the shear stress of the wind. Non-erodible 

elements include stones and bulk surface material but do not include flat 

or standing vegetation. For surfaces with non-erodible elements, 

determine corrections to the TFV by identifying the fraction of the 

survey area, as viewed from directly overhead, that is occupied by nonerodible elements using the following procedure. For a more detailed 

description of this procedure, see §B.5 - the Rock Test Method. Select a 

survey area of 1 meter by 1 meter that represents a random portion of the 

overall conditions of the site. Where many non-erodible elements lie 

within the survey area, separate the non-erodible elements into groups 

according to size. For each group, calculate the overhead area for the 

non-erodible elements according to the following equations: 

 Average Length × Average Width = Average Dimensions . ... ..... .. ... ... ... ... ... .... Eq. 1 

 Average Dimensions × Number of Elements = Overhead Area . ... ... ... ... ... ... ....... Eq. 2 

Overhead Area of Group 1 + Overhead Area of Group 2 (etc.) = Total Overhead Area .. 

... ... ... ... .. ... ... ... .. ... ... ... .. ... ... ... .. ... ... ... .. ... ... ... .. ... ... ... .. ... ... ... ..... Eq. 3 

 Total Overhead Area ÷ 2 = Total Frontal Area ... ... .. .... ... ... .. ... ... ...... ... ... .. ... . Eq. 4 

(Total Frontal Area ÷ Survey Area) × 100 = Percent Cover of Non-Erodible Elements .. 

.. ... ... .. .. ... ... .. .. ... ... .. .. ... ... .. .. ... ... .. .. ... ... .. .. ... ... .. .. ... ... .. .. ... ... .. . ...... Eq. 5 

Note: Ensure consistent units of measurement (e.g., square meters or square inches) when 

calculating percent cover. 

Repeat this procedure on an additional two distinct survey areas that represent a random 

portion of the overall conditions of the site and average the results. Use Table 2 to 

identify the correction factor for the percent cover of non-erodible elements. Multiply the 

TFV by the corresponding correction factor to calculate the TFV corrected for nonerodible elements. 

Table 2. Correction Factors for Threshold Friction Velocity 

Percent Cover of Non-Erodible Elements Factor Correction Factor 

 Greater than or equal to 10% 5 

 Greater than or equal to 5% and less than 10% 3 

 Less than 5% and greater than or equal to 1% 2 

 Less than 1% None 
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3. Determination of Flat Vegetative Cover: Flat vegetation includes attached 

(rooted) vegetation or unattached vegetative debris lying on the surface with a 

predominant horizontal orientation that is not subject to movement by wind. Flat 

vegetation, which is dead but firmly attached, shall be considered equally 

protective as live vegetation. Stones or other aggregate larger than 1 centimeter 

in diameter shall be considered protective cover in the course of conducting the 

line transect test method. Where flat vegetation exists, conduct the following line 

transect test method. 

a. Line Transect Test Method: Stretch a 100-foot measuring tape across a 

survey area that represents a random portion of the overall conditions of 

the site. Firmly anchor both ends of the measuring tape into the surface 

using a tool such as a screwdriver, with the tape stretched taut and close 

to the soil surface. If vegetation exists in regular rows, place the tape 

diagonally (at approximately a 45° angle) away from a parallel or 

perpendicular position to the vegetated rows. Pinpoint an area the size of 

a 3/32 inch diameter brazing rod or wooden dowel centered above each 

1-foot interval mark along one edge of the tape. Count the number of 

times that flat vegetation lies directly underneath the pinpointed area at 

1-foot intervals. Consistently observe the underlying surface from a 90° 

angle directly above each pinpoint on one side of the tape. Do not count 

the underlying surface as vegetated if any portion of the pinpoint extends 

beyond the edge of the vegetation underneath in any direction. If clumps 

of vegetation or vegetative debris lie underneath the pinpointed area, 

count the surface as vegetated, unless bare soil is visible directly below 

the pinpointed area. When 100 observations have been made, add 

together the number of times a surface was counted as vegetated. This 

total represents the percent of flat vegetation cover (e.g., if 35 positive 

counts were made, then vegetation cover is 35%). If the survey area that 

represents a random portion of the overall conditions of the site is too 

small for 100 observations, make as many observations as possible. 

Then multiply the count of vegetated surface areas by the appropriate 

conversion factor to obtain percent cover. For example, if vegetation 

was counted 20 times within a total of 50 observations, divide 20 by 50 

and multiply by 100 to obtain a flat vegetation cover of 40%. 

b. [Required Number of Observations] Conduct the line transect test 

method, as described above, an additional two times on areas that 

represent a random portion of the overall conditions of the site and 

average results. 

4. Determination of Standing Vegetative Cover: Standing vegetation includes 

vegetation that is attached (rooted) with a predominant vertical orientation. 

Standing vegetation, which is dead but firmly rooted, shall be considered equally 

protective as live vegetation. Conduct the following standing vegetation test 

method to determine if 30% cover or more exists. If the resulting percent cover 

is less than 30% but equal to or greater than 10%, then conduct the test in §B.2 

(Determination of Threshold Friction Velocity [TFV]) in order to determine if 

the site is stabilized, such that the standing vegetation cover is equal to or greater 
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than 10%, where threshold friction velocity, corrected for non-erodible elements, 

is equal to or greater than 43 cm/second. 

a. [Define Survey Area] For standing vegetation that consists of large, 

separate vegetative structures (e.g., shrubs and sagebrush), select a 

survey area that represents a random portion of the overall conditions of 

the site that is the shape of a square with sides equal to at least 10 times 

the average height of the vegetative structures. For smaller standing 

vegetation, select a survey area of three feet by three feet. 

b. [Calculate Frontal Silhouette Area] Count the number of standing 

vegetative structures within the survey area. Count vegetation, which 

grows in clumps as a single unit. Where different types of vegetation 

exist and/or vegetation of different height and width exists, separate the 

vegetative structures with similar dimensions into groups. Count the 

number of vegetative structures in each group within the survey area. 

Select an individual structure within each group that represents the 

average height and width of the vegetation in the group. If the structure 

is dense (e.g., when looking at it vertically from base to top there is little 

or zero open air space within its perimeter), calculate and record its 

frontal silhouette area, according to Equation 6. Also, use Equation 6 to 

estimate the average height and width of the vegetation if the survey area 

is larger than nine square feet. Otherwise, use the procedure in §B.4.c 

(Vegetative Density) to calculate the frontal silhouette area. Then 

calculate the percent cover of standing vegetation according to Equations 

7, 8, and 9. 

 (Average Height) × (Average Width) = Frontal Silhouette Area .. .... ... ... ... .. ... ..... Eq. 6 

(Frontal Silhouette Area of Individual Vegetative Structure) × (Number of Vegetation 

Structures Per Group) = Frontal Silhouette Area of Group . ... .. ... .. ... ... ... .. ... ...... Eq. 7 

Frontal Silhouette Area of Group 1 + Frontal Silhouette Area of Group 2 (etc.) = Total 

Frontal Silhouette Area. .. ... .. ... ... ... .. ... ... ... .. ... ... ... ... ... .. ... ... ... .. ... ... ... .. . Eq. 8 

(Total Frontal Silhouette Area ÷ Survey Area) × 100 = Percent Cover of Standing 

Vegetation ... ... . ... ... . ... ... . ... ... . ... ... . ... ... . ... ... . ... ... . ... ... . ... ... . ... ... . .. ... Eq. 9 

[(Number of Circled Gridlines within the Outlined Area Counted that are not Covered by 

Vegetation ÷ Total Number of Gridline Intersections within the Outlined Area) × 100] = 

Percent Open Space .. . . ... ... . ... ... . ... ... . ... ... . ... . . . ... ... . . ... ... . ... ... . ... . ... Eq. 10 

 100 – Percent Open Space = Percent Vegetative Density .. ... ... ... ... ... ... ... ... .. .. Eq. 11 

 Percent Vegetative Density ÷ 100 = Vegetative Density ... .. .... ... ... ... ... ... .. ... ... Eq. 12 

[Max. Height × Max. Width] × [Vegetative Density/0.4])0.5 = Frontal Silhouette Area .. 

.. ... ... ... .. ... ... ... .. ... ... ... .. ... ... ... .. ... ... ... .. ... ... ... .. ... ... ... ... ... .. ... ... ... ... Eq. 13 
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Note: Ensure consistent units of measurement (e.g., square meters or square inches) when 

calculating percent cover. 

c. Vegetative Density Factor: Cut a single, representative piece of 

vegetation (or consolidated vegetative structure) to within 1 cm of 

surface soil. Using a white paper grid or transparent grid over white 

paper, lay the vegetation flat on top of the grid (but do not apply pressure 

to flatten the structure). Grid boxes of 1-inch or 1⁄2-inch squares are 

sufficient for most vegetation when conducting this procedure. Using a 

marker or pencil, outline the shape of the vegetation along its outer 

perimeter, according to Figure B, C, or D, as appropriate. (Note: Figure 

C differs from Figure D primarily in that the width of vegetation in 

Figure C is narrow at its base and gradually broadens to its tallest height. 

In Figure D, the width of the vegetation generally becomes narrower 

from its midpoint to its tallest height.) Remove the vegetation, count and 

record the total number of gridline intersections within the outlined area, 

but do not count gridline intersections that connect with the outlined 

shape. There must be at least 10 gridline intersections within the 

outlined area and preferably more than 20, otherwise, use smaller grid 

boxes. Draw small circles (no greater than a 3/32 inch diameter) at each 

gridline intersection counted within the outlined area. Replace the 

vegetation on the grid within its outlined shape. From a distance of 

approximately 2 feet directly above the grid, observe each circled 

gridline intersection. Count and record the number of circled gridline 

intersections that are not covered by any piece of the vegetation. To 

calculate percent vegetative density, use Equations 10 and 11. If percent 

vegetative density is equal to or greater than 30, use an equation (one of 

the Equations 16, 17, or 18) that matches the outline used to trace the 

vegetation (Figure B, C, or D) to calculate its frontal silhouette area. 

Outline the shape of the vegetation along its outer perimeter, as either a 

cylinder; an inverted cone; or the upper portion of a sphere, as 

appropriate. For classification purposes, vegetation that generally flares 

with increasing height should be considered an inverted cone. 

Vegetation that generally narrows in width above a midpoint should be 

considered as the upper portion of a sphere. If percent vegetative density 

is less than 30, use Equations 12 and 13 to calculate the frontal silhouette 

area. 

Figure B. Cylinder - See MaricopaAppendixC (pdf, 2132 KB), page 10, available on-line 

at 

http://yosemite.epa.gov/R9/r9sips.nsf/AgencyProvision/0A50F4E53BD113898825735B0

065A8D6?OpenDocument. 

 Frontal Silhouette Area = Maximum Height × Maximum Width ..... ... ... ... .. ... .... Eq. 16 

Figure C. Inverted Cone. See MaricopaAppendixC (pdf, 2132 KB), page 11, available 

on-line at 

http://yosemite.epa.gov/R9/r9sips.nsf/AgencyProvision/0A50F4E53BD113898825735B0

065A8D6?OpenDocument. 
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Inverted Cone Frontal Silhouette Area = Maximum Height × 1⁄2 Maximum Width .. .. ... 

... ... .. ... .. ... ... .. ... .. ... ... .. ... .. ... ... .. ... .. ... ... .. ... .. ... ... .. ... .. ... ... .. .. ... .... Eq. 17 

Figure D. Upper Sphere. See MaricopaAppendixC (pdf, 2132 KB), page 12, available 

on-line at 

http://yosemite.epa.gov/R9/r9sips.nsf/AgencyProvision/0A50F4E53BD113898825735B0

065A8D6?OpenDocument. 

Upper Sphere - Frontal Silhouette Area = (3.14 × Maximum Height × 1⁄2 Maximum 

Width) ÷ 2 ... .. .. ... .. ... ... .. ... .. ... ... .. . .. .. ... .. ... ... .. ... .. ... ... .. . . .. ... ... .. . .. . Eq. 18 

5. Rock Test Method: The Rock Test Method examines the wind-resistance effects 

of rocks and other non-erodible elements on disturbed surfaces. Non-erodible 

elements are objects larger than 1 centimeter (cm) in diameter that remain firmly 

in place even on windy days. Typically, non-erodible elements include rocks, 

stones, glass fragments, and hard-packed clumps of soil lying on or embedded in 

the surface. Vegetation does not count as a non-erodible element in this method. 

The purpose of this test method is to estimate the percent cover of non-erodible 

elements on a given surface to see whether such elements take up enough space 

to offer protection against windblown dust. For simplification, the following test 

method refers to all non-erodible elements as “rocks”. 

a. [Test Area] Select a 1-meter × 1-meter survey area that represents the 

general rock distribution on the surface. (A 1-meter × 1-meter area is 

slightly greater than a 3-foot × 3-foot area.) Mark off the survey area by 

tracing a straight, visible line in the dirt along the edge of a measuring 

tape or by placing short ropes, yard sticks, or other straight objects in a 

square around the survey area. 

b. [Initial Surface Characterization] Without moving any of the rocks or 

other elements, examine the survey area. Since rocks >3/8 inch (1 cm) in 

diameter are of interest, measure the diameter of some of the smaller 

rocks to a get a sense for which rocks need to be considered. 

c. [Grouping Characterization of Rocks] Mentally group the rocks >3/8 

inch (1 cm) diameter lying in the survey area into small, medium, and 

large size categories. Or, if the rocks are all approximately the same 

size, simply select a rock of average size and typical shape. Without 

removing any of the rocks from the ground, count the number of rocks in 

the survey area in each group and write down the resulting number. 

d. [Determination of Average Individual Rock Area] Without removing 

rocks, select one or two average-size rocks in each group and measure 

the length and width. Use either metric units or standard units. Using a 

calculator, multiply the length times the width of the rocks to get the 

average dimensions of the rocks in each group. Write down the results 

for each rock group. 
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e. [Calculation of Aggregate Total Rock Area] For each rock group, 

multiply the average dimensions (length times width) by the number of 

rocks counted in the group. Add the results from each rock group to get 

the total rock area within the survey area. 

f. [Calculation of Total Rock Area] Divide the total rock area by two (to 

get frontal area). Divide the resulting number by the size of the survey 

area (making sure the units of measurement match), and multiply by 100 

for percent rock cover. For example, the total rock area is 1,400 square 

centimeters, divide 1,400 by 2 to get 700. Divide 700 by 10,000 (the 

survey area is 1 meter by 1 meter, which is 100 centimeters by 100 

centimeters or 10,000 square centimeters), and multiply by 100. The 

result is 7% rock cover. If rock measurements are made in inches, 

convert the survey area from meters to inches (1 inch = 2.54 

centimeters). 

g. [Characterization of Rock Cover Across Entire Site] Select and mark off 

two additional survey areas and repeat the procedures described above in 

subsections a. through f. Make sure the additional survey areas also 

represent the general rock distribution on the site. Average the percent 

cover results from all three survey areas to estimate the average percent 

of rock cover. 

h. [Initial Rock Cover Stabilization Determination] If the average rock 

cover is greater than or equal to 10%, the surface is stable. If the average 

rock cover is less than 10%, follow the procedures in the following 

subsection i. 

i. [Combined Rock Cover/TFV Stabilization Determination] If the average 

rock cover is less than 10%, the surface may or may not be stable. 

Follow the procedures in Subsection B.2 (Determination of Threshold 

Friction Velocity [TFV]) of this rule and use the results from the rock 

test method as a correction (i.e., multiplication) factor. If the rock cover 

is at least 1%, such rock cover helps to limit windblown dust. However, 

depending on the soil's ability to release fine dust particles into the air, 

the percent rock cover may or may not be sufficient enough to stabilize 

the surface. It is also possible that the soil itself has a high enough TFV 

to be stable without even accounting for rock cover. 

j. [TFV Correction Based on Partial Rock Cover] After completing the 

procedures to calculate the TFV as described in the preceding subsection, 

use Table 2 to identify the appropriate correction factor to the TFV, 

depending on the percent rock cover. Multiply the correction factor by 

the TFV value for a final TFV estimate that is corrected for non-erodible 

elements. 

C. TEST METHODS ADOPTED BY REFERENCE: The following test methods are 

adopted by reference. These adoptions by reference include no future editions or 
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amendments. Copies of the test methods listed in this section are available for review at 

Pinal County Air Quality, 31 North Pinal St., Florence, AZ 85232. 

1. ASTM Method C136-06 (“Standard Test Method for Sieve Analysis of Fine and 

Coarse Aggregates”), 2006 edition. 

2. ASTM Method D2216-05 (“Standard Test Method for Laboratory Determination 

of Water (Moisture) Content of Soil and Rock by Mass”), 2005 edition. 

3. ASTM Method D1557-02e1 (“Test Method for Laboratory Compaction 

Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700 kNm/m3

)”), 2002 edition. 

[ Adopted June 3, 2009, effective August 26, 2009]

4-9-340. Visual Opacity Test Methods 

A. General Provisions 

1. Applicability: These methods apply to the determination of opacity of visible 

emissions under this Chapter 4. 

2. Principle: the opacity of emissions from sources of visible emissions is 

determined visually by an observer qualified according to the procedures of §G 

of this rule. 

3. Procedures: An observer qualified, in accordance with §G of this rule shall use 

the procedures set forth in this Article for visually determining the opacity of 

emissions. 

B. Procedures for Determining Opacity from Emissions From Stationary Sources 

1. Opacity from stationary point sources shall be determined in accord with EPA 

Method 9, as adopted by reference herein. 

 2. Adoption by Reference 

The following test methods are adopted by reference. These adoptions by 

reference include no future editions or amendments. Copies of the test methods 

listed in this section are available for review at Pinal County Air Quality, 31 

North Pinal St., Florence, AZ 85232. 

 a. EPA Reference Method 9, 40 CFR Part 60, Appendix A (7/1/08). 

C. Procedures for Determining Time-Averaged Opacity from Intermittent Operations 

1. [Applicability - Intermittent Plume Average Opacity Determination for 

Operations] 
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The purpose of this method is determine the opacity of non-continuous dust 

plumes caused by activities including, but not limited to, bulk material 

loading/unloading, non-conveyorized screening, or trenching with backhoes. 

 

 2. Opacity Determination Process 

a. Position: Stand at least 25 feet from the dust-generating operation in 

order to provide a clear view of the emissions with the sun oriented in the 

140° sector to the back. Choose a discrete portion of the operation for 

observation, such as the unloading point, not the whole operation. 

Following the above requirements, make opacity observations so that the 

line of vision is approximately perpendicular to the dust plume and wind 

direction. If multiple plumes are involved, do not include more than one 

plume in the line of sight at one time. 

b. Initial Fallout Zone: The initial fallout zone within the plume must be 

identified. Record the distance from the equipment or path that is your 

identified initial fallout zone. The initial fallout zone is that area where 

the heaviest particles drop out of the entrained fugitive dust plume. 

Opacity readings should be taken at the maximum point of the entrained 

fugitive dust plume that is located outside the initial fallout zone. 

 c. Field Records: Note the following on an observational record sheet: 

i. Location of dust-generating operation, type of operation, type of 

equipment in use and activity, and method of control used, if 

any; 

ii. Observer's name, certification data and affiliation, a sketch of the 

observer's position relative to the dust-generating operation, and 

observer's estimated distance and direction to the location of the 

dust-generating operation; 

iii. Time that readings begin, approximate wind direction, estimated 

wind speed, description of the sky condition (presence and color 

of clouds); and 

 iv. Color of the plume and type of background. 

d. Observations. Make opacity observations, to the extent possible, using a 

contrasting background that is perpendicular to the line of vision. Make 

two observations per discrete activity, beginning with the first reading at 

zero seconds and the second reading at five seconds. The zero-second 

observation should begin immediately after a plume has been created 

above the surface involved. Do not look continuously at the plume but, 

instead, observe the plume briefly at zero seconds and then again at five 

seconds. 
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e. Recording Observations: Record the opacity observations to the nearest 

5% on an observational record sheet. Each momentary observation 

recorded represents the average opacity of emissions for a five-second 

period. Repeat observations until you have recorded at least a total of 12 

consecutive opacity readings. The 12 consecutive readings must be 

taken within the same period of observation but must not exceed one 

hour. Observations immediately preceding and following interrupted 

observations can be considered consecutive (e.g., vehicle traveled in 

front of path, plume doubled over). 

f. Data Reduction: Average 12 consecutive opacity readings together. If 

the average opacity reading is equal to or less than the numerical 

standard in the underlying rule, the dust-generating operation is in 

compliance. 

D. Procedures for Determining Average Opacity from Vehicle Movement 

1. [Applicability - Intermittent Plume Average Opacity Determination for Vehicular 

Movement]. The purpose of this test method is to estimate the percent opacity of 

fugitive dust plumes caused by vehicle movement on unpaved roads and unpaved 

parking lots. This method can only be conducted by an individual who has 

received certification as a qualified observer. Qualification and testing 

requirements can be found in Section G of this Rule. 

 2. Opacity Determination Process 

a. Step 1 [- Position]: Stand at least 16.5 feet from the fugitive dust source 

in order to provide a clear view of the emissions with the sun oriented in 

the 140° sector to the back. Following the above requirements, make 

opacity observations so that the line of vision is approximately 

perpendicular to the dust plume and wind direction. If multiple plumes 

are involved, do not include more than one plume in the line of sight at 

one time. 

b. Step 2. [- Field Records]: Record the fugitive dust source location, 

source type, method of control used, if any, observer's name, certification 

data and affiliation, and a sketch of the observer's position relative to the 

fugitive dust source. Also, record the time, estimated distance to the 

fugitive dust source location, approximate wind direction, estimated 

wind speed, description of the sky condition (presence and color of 

clouds), observer's position to the fugitive dust source, and color of the 

plume and type of background on the visible emission observation from 

both when opacity readings are initiated and completed. 

c. Step 3 [- Observations]: Make opacity observations, to the extent 

possible, using a contrasting background that is perpendicular to the line 

of vision. Make opacity observations approximately 1 meter above the 

surface from which the plume is generated. Note that the observation is 

to be made at only one visual point upon generation of a plume as 
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opposed to visually tracking the entire length of a dust plume as it is 

created along a surface. Make two observations per vehicle, beginning 

with the first reading at zero seconds and the second reading at five 

seconds. The zero-second observation should begin immediately after 

the plume has been created above the surface involved. Do not look 

continuously at the plume but, instead, observe the plume briefly at zero 

seconds and then again at five seconds. 

d. Step 4 [- Recording Observations - #1]: Record the opacity observations 

to the nearest 5% on an observational record sheet. Each momentary 

observation recorded represents the average opacity of emissions for a 5-

second period. While it is not required by the test method, EPA 

recommends that the observer estimate the size of vehicles which 

generate dust plumes for which readings are taken (e.g. mid-size 

passenger car or heavy-duty truck) and the approximate speeds the 

vehicles are traveling when the readings are taken. 

e. Step 5 [- Recording Observations - #2]: Repeat Step 3 and Step 4 until 

you have recorded a total of 12 consecutive opacity readings. This will 

occur once six vehicles have driven on the source in your line of 

observation for which you are able to take proper readings. The 12 

consecutive readings must be taken within the same period of 

observation but must not exceed 1 hour. Observations immediately 

preceding and following interrupted observations can be considered 

consecutive. 

f. Step 6 [- Data Reduction]: Average the 12 opacity readings together. If 

the average opacity reading is equal to or less than the numerical 

standard in the underlying rule, the source is in compliance. 

E. Procedures for Determining Time-Averaged Opacity from Continuous Operations 

 1. [Applicability - Continuous Plume Average Opacity Determination for Operations] 

The purpose of this method is to determine the opacity of continuous dust plumes 

caused by equipment and activities including but not limited to graders, 

trenchers, paddlewheels, blades, clearing, leveling, and raking. 

 2. Opacity Determination Process 

a. Position: Stand at least 25 feet from the dust-generating operation to 

provide a clear view of the emissions with the sun oriented in the 140°

sector to your back. Following the above requirements, make opacity 

observations so that the line of vision is approximately perpendicular to 

the dust plume and wind direction. 

b. Dust Plume: Evaluate the dust plume generation and determine if the 

observations will be made from a single plume or from multiple related 

plumes. 
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i. If a single piece of equipment is observed working, then all 

measurements should be taken off the resultant plume as long as 

the equipment remains within the 140° sector to the back. 

ii. If there are multiple related sources or multiple related points of 

emissions of dust from a particular activity, or multiple pieces of 

equipment operating in a confined area, opacity readings should 

be taken at the densest point within the discrete length of 

equipment travel path within the 140° sector to the back. 

Readings can be taken for more than one piece of equipment 

within the discrete length of travel path within the 140° sector to 

the back. 

c. Initial Fallout Zone: The initial fallout zone within the plume must be 

identified. Record the distance from the equipment or path that is your 

identified initial fallout zone. The initial fallout zone is that area where 

the heaviest particles drop out of the entrained fugitive dust plume. 

Opacity readings should be taken at the maximum point of the entrained 

fugitive dust plume that is located outside the initial fallout zone. 

 d. Field Records: Note the following on an observational record sheet: 

i. Location of the dust-generating operation, type of operation, type 

of equipment in use and activity, and method of control used, if 

any; 

ii. Observer's name, certification data and affiliation, a sketch of the 

observer's position relative to the dust-generating operation, and 

observer's estimated distance and direction to the location of the 

dust-generating operation; and 

iii. Time that readings begin, approximate wind direction, estimated 

wind speed, description of the sky condition (presence and color 

of clouds). 

e. Observations: Make opacity observations, to the extent possible, using a 

contrasting background that is perpendicular to the line of vision. Make 

opacity observations at a point beyond the fallout zone. The 

observations should be made at the densest point. Observations will be 

made every 10 seconds until at least 12 readings have been recorded. Do 

not look continuously at the plume, but observe the plume momentarily 

at 10-second intervals. If the equipment generating the plume travels 

outside the field of observation or if the equipment ceases to operate, 

mark an "X" for the 10-second reading interval. Mark an "X" when 

plumes are stacked or doubled, either behind or in front, or become 

parallel to line of sight. Opacity readings identified as "X" shall be 

considered interrupted readings. 
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f. Recording Observations: Record the opacity observations to the nearest 

5% on an observational record sheet. Each momentary observation 

recorded represents the average opacity of emissions for a 10-second 

period. 

g. Data Reduction: Average 12 consecutive opacity readings together. If 

the average opacity reading is equal to or less than the numerical 

standard in the underlying rule, the dust-generating operation is in 

compliance. 

F. Procedures for Determining the Frequency of Visible Emissions; Time Aggregation 

Method 

 1. Applicability - Aggregate Quantification of Visible Emission Duration 

The purpose of this method is to determine the amount of time that visible 

emissions occur during the observation period (i.e., the accumulated emission 

time). 

 2. Adoption by Reference 

The following test methods are adopted by reference. These adoptions by 

reference include no future editions or amendments. Copies of the test methods 

listed in this section are available for review at Pinal County Air Quality, 31 

North Pinal St., Florence, AZ 85232. 

a. EPA Reference Method 22 (“Visual Determination of Fugitive 

Emissions from Material Sources and Smoke Emissions from Flares”), 

2000 edition. 

G. Qualification and Testing 

1. Certification Requirements: To receive certification as a qualified observer, a 

candidate must be tested and demonstrate the ability to assign opacity readings in 

5% increments to 25 different black plumes and 25 different white plumes, with 

an error not to exceed 15% opacity on any one reading and an average error not 

to exceed 7.5% opacity in each category. Candidates shall be tested according to 

the procedures described in this subsection. Any smoke generator shall be 

equipped with a smoke meter, which meets the requirements of this subsection. 

Certification tests that do not meet the requirements of this subsection are not 

valid. The certification shall be valid for a period of 6 months, and after each 6-

month period the qualification procedures must be repeated by an observer in 

order to retain certification. 

2. Certification Procedure: The certification test consists of showing the candidate 

a complete run of 50 plumes, 25 black plumes and 25 white plumes, generated by 

a smoke generator. Plumes shall be presented in random order within each set of 

25 black and 25 white plumes. The candidate assigns an opacity value to each 

plume and records the observation on a suitable form. At the completion of each 
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run of 50 readings, the score of the candidate is determined. If a candidate fails 

to qualify, the complete run of 50 readings must be repeated in any retest. The 

smoke test may be administered as part of a smoke school or training program, 

and may be preceded by training or familiarization runs of the smoke generator, 

during which candidates are shown black and white plumes of known opacity. 

3. Smoke Generator Specifications: Any smoke generator used for the purpose of 

this subsection shall be equipped with a smoke meter installed to measure opacity 

across the diameter of the smoke generator stack. The smoke meter output shall 

display in-stack opacity, based upon a path length equal to the stack exit diameter 

on a full 0% to 100% chart recorder scale. The smoke meter optical design and 

performance shall meet the specifications shown in Table 3 of this appendix. 

The smoke meter shall be calibrated as prescribed in this subsection prior to 

conducting each smoke reading test. At the completion of each test, the zero and 

span drift shall be checked, and if the drift exceeds plus or minus 1% opacity, the 

condition shall be corrected prior to conducting any subsequent test runs. The 

smoke meter shall be demonstrated, at the time of installation, to meet the 

specifications listed in Table 3 of this appendix. This demonstration shall be 

repeated following any subsequent repair or replacement of the photocell or 

associated electronic circuitry, including the chart recorder or output meter, or 

every 6 months, whichever occurs first. 

a. Calibration: The smoke meter is calibrated after allowing a minimum of 

30 minutes warm-up by alternately producing simulated opacity of 0% 

and 100%. When stable response at 0% or 100% is noted, the smoke 

meter is adjusted to produce an output of 0% or 100%, as appropriate. 

This calibration shall be repeated until stable 0% and 100% readings are 

produced without adjustment. Simulated 0% and 100% opacity values 

may be produced by alternately switching the power to the light source 

on and off while the smoke generator is not producing smoke. 

b. Smoke Meter Evaluation: The smoke meter design and performance are 

to be evaluated as follows: 

i. Light Source: Verify, from manufacturer's data and from voltage 

measurements made at the lamp, as installed, that the lamp is 

operated within plus or minus 5% of the nominal rated voltage. 

ii. Spectral Response of Photocell: Verify from manufacturer's data 

that the photocell has a photopic response (i.e., the spectral 

sensitivity of the cell shall closely approximate the standard 

spectral-luminosity curve for photopic vision which is referenced 

in (b) of Table 3 of this appendix). 

iii. Angle of View: Check construction geometry to ensure that the 

total angle of view of the smoke plume, as seen by the photocell, 

does not exceed 15°. Calculate the total angle of view as 

follows: 
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 Total Angle of View = 2 tan-1 d/2L 

 where: 

d = The photocell diameter + the diameter of the limiting 

aperture; and 

 L = The distance from the photocell to the limiting aperture. 

The limiting aperture is the point in the path between the 

photocell and the smoke plume where the angle of view is most 

restricted. In smoke generator smoke meters, this is normally an 

orifice plate. 

iv. Angle of Projection: Check construction geometry to ensure that 

the total angle of projection of the lamp on the smoke plume 

does not exceed 15°. Calculate the total angle of projection as 

follows: 

 Total Angle of Projection = 2 tan-1 d/2L 

 Where: 

d = The sum of the length of the lamp filament + the diameter of 

the limiting aperture; and 

 L = The distance from the lamp to the limiting aperture. 

 v. Calibration Error: Using neutral-density filters of known 

opacity, check the error between the actual response and the 

theoretical linear response of the smoke meter. This check is 

accomplished by first calibrating the smoke meter, according to 

subsection G.3.a , and then inserting a series of three neutraldensity filters of nominal opacity of 20%, 50%, and 75% in the 

smoke meter path length. Use filters calibrated within plus or 

minus 2%. Care should be taken when inserting the filters to 

prevent stray light from affecting the meter. Make a total of five 

nonconsecutive readings for each filter. The maximum opacity 

error on any one reading shall be plus or minus 3%. 

 vi. Zero and Span Drift: Determine the zero and span drift by 

calibrating and operating the smoke generator in a normal 

manner over a 1-hour period. The drift is measured by checking 

the zero and span at the end of this period. 

 vii. Response Time: Determine the response time by producing the 

series of five simulated 0% and 100% opacity values and 

observing the time required to reach stable response. Opacity 

values of 0% and 100% may be simulated by alternately 
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switching the power to the light source off and on while the 

smoke generator is not operating. 

Table 3. Smoke Meter Design and Performance Specifications 

 Parameter Specification 

1. Light source Incandescent lamp operated at nominal rated 

voltage 

2. Spectral response of photocell Photoptic (daylight spectral response of the human 

eye) 

 Angle of view 5° maximum total angle 

 Angle of projection 5° maximum total angle 

 Calibration error Plus or minus 3% opacity maximum 

 Zero and span drift Plus or minus 1% opacity 30 minutes 

3. Response time Less than or equal to 5 seconds 

[ Adopted June 3, 2009, effective August 26, 2009]