90.1 FUGITIVE DUST From OPEN AREAs AND VACANT LOTS

90.1.1 Purpose: To limit the EMissioN of PARTIcuLATE MATTER into the AMBIENT

AIR from OPEN AREAS AND VACANT LOTS.

Applicability: The provisions of this Regulation shall apply to OPEN AREAs

AND VAcANT LOTS which are located in the PM, 0 N0NATrAINMEm- AREA

(HYDR0GRAPHIc BASIN 212) and the Apex Valley (HYDR0GRAPHIc BAsINs 216

and 217). Nothing in Section 90 of these Regulations shall be construed to

prevent enforcement of Section 40 (Prohibition of NUISANCE Conditions) of

these Regulations. The provisions of this Regulation shall not apply to

Normal Farm Cultural Practices or the raising of fowl or animals. The

provisions of this Regulation shall not apply to STATIONARY SOURCES as

defined in Section 0, except that these control measures shall be

considered as part of a BACT determination.

90.1.3 Effective Date Of This Regulation:

90.1.3.1 Section 90, adopted by the District Board of Health of Clark County on June

22, 2000, shall be effective in HYDR0GRAPHIc BAsIN 212 on January 1,

2001, except as otherwise provided herein.

90.1.3.2 Section 90 shall be effective in HYDR0GRAPHIc BASINS 216 and 217 on April

1, 2002, except as otherwise provided herein.

90.2 Requirements:

OPEN AREAs AND VACANT LOTS: If OPEN AREAS AND VACANT LOTS are

5,000 square feet or larger and are disturbed by any means, including use

• by MOTOR VEHICLES and/or OFF-RoAD MOTOR VEHICLES or material

dumping, then the OWNER AND/OR OPERAToR of such OPEN AREAS AND

V

VACANT LOTS shall implement one or more of the CONTROL MEASURES

described in Subsection 90.2.1.1 of this Regulation within 30 calendar

days following the initial discovery of disturbance or vehicle use on OPEN

AREAs AND VACANT LOTS. The OWNER AND/OR OPERATOR shall implement

all control measures necessary to limit the disturbance of open areas and

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SECTION 90- FUGITIVE DUST FROM OPEN AREAS AND VACANT

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vacant lots in accordance with the requirements of this regulation.

Advisory Notice: In order to conserve water to the greatest extent

practicable, the use of RECLAIMED WATER is highly encouraged.

90.2.1.1 CONTROLMEASURES:

(a) Where there is evidence of soil disturbance by MOTOR VEHICLES

and/or OFF-ROAD VEHIcLE use, prevent MOTOR VEHICLE and/or OFFROAD VEHICLE trespassing, parking, and/or access, by installing

barriers, curbs, fences, gates, posts, signs, shrubs, trees, or other

effective traffic Control Measures. A stable surface area shall be

established and maintained by using one of the CONTROL

MEAsuREs set forth in Subsections 90.2.1.1(b) or (c) or by the

effective application of water in compliance with the stabilization

standards set forth in Subsection 90.2.1.2. Where measures to

prevent vehicular trespassing and movement are not effective, the

application of water will not be utilized for surface stabilization. For

the purposes of this Subsection, use of or parking on OPEN AREAs

AND VACANT LOTS for noncommercial and non-institutional

purposes by the OWNER AND/OR OPERATOR of such OPEN AREAs

AND VACANT LOTS shall not be considered vehicle use under this

Subsection. In addition, vehicle use related to landscaping

maintenance shall not be considered vehicle use under this

Subsection. For the purpose of this Regulation, landscape

maintenance does not include grading, trenching, or any other

mechanized surface disturbing activities performed to establish

initial landscapes or to redesign existing landscapes; or

(b) Where a DISTURBED SURFAcE AREA exists (including disturbed

surfaces caused by MOTOR VEHICLES), uniformly apply and maintain

surface gravel or DUST PALuATIvEs to all areas disturbed by MOTOR

VEHIcLES in compliance with one of the stabilization standards

described in Subsection 90.2.1.2 of this Regulation; or

(c) Where a DISTuRBED SURFACE AREA exists (including disturbed

surfaces caused by MOTOR VEHICLES and/or OFF-ROAD MOTOR

VEHIcLEs), apply and maintain an alternative CONTROL MEASURE

approved in writing by the CONTROL OFFICER and the Region IX

ADMINIsTRAToR of the Environmental Protection Agency (EPA).

90.2.1.2 Stabilization Standards:

(a) A visible crust shall be established, as determined by

Subsection 90.4.1.1 (The Drop Ball/Steel Ball Test) of these

Regulations; or,

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(b) A percent cover that is equal to or greater than 20% for non

erodible elements shall be established, as determined by

Subsection 90.4.1.2 (Rock Test Method) of these Regulations; or,

(c) A threshold friction velocity, corrected for non-erodible elements of

100 cm/second or higher, shall be established, as determined by

Subsection 90.4.1.3 (Determination Of Threshold Friction Velocity)

of this Regulation; or,

(d) An alternative test method approved in writing by the CONTROL

OFFIcER and the Region IX ADMINIsTRAToR of the EPA.

90.2.2 Dust Mitigation Plans Required: Any OWNER ANDIOR OPERATOR of

OPEN AREAs AND VACANT LOTS having a cumulative area of 101000 acres

or greater must submit a dust mitigation plan to the Department of Air

Quality Management for approval by March 31, 2003, in a format

prescribed by the CONTROL OFFICER.

90.2.3 Mechanized Weed Abatement andlor Trash Removal: If machinery is

V used to clear weeds ortrash from OPEN AREAs AND VACANT LOTS of

5,000 square feet or larger, then the following Control Measures set forth

in Subsection 90.2.3.1 shall be applied. Advisory Notice: In order to

conserve water to the greatest extent practicable, the use of REcLAIMED

WATER is highly encouraged.

90.2.3.1 CoNTRoL MEASURES

V

(a) Pre-wet surface soils before mechanized weed abatement and/or

trash removal occurs; and,

(b) Maintain dust control measures while mechanized weed abatement

and/or trash removal is occurring; and,

(c) PAVE, apply gravel, apply water, or apply a suitable DUST

PALLIATIVE, in compliance with the stabilization standards set forth

in Subsection 90.2.1.2 of this Regulation, after mechanized weed

abatement and/or trash removal occurs.

90.3 Record Keeping Requirements

90.3.1 Record Keeping: Any PERSON subject to the requirements of this

Regulation shall compile and retain records that provide evidence of

CONTROL MEAsuRE application, by indicating type of treatment or CONTROL

MEAsuRE, extent of coverage, and date applied. The records and

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supporting documentation shall be made available to the CONTROL

OFFIcER within 24 hours of a written request.

90.3.2 Record Retention: Copies of the records required by Subsection 90.3.1

(Record Keeping Requirements) of this Regulation shall be retained for at

least one year.

90.4 Test Methods

90.4.1 Stabilization Standards For OPEN AREAS AND VACANT LOTS: The test

methods described in Subsections 90.4.1.1 through Subsections 90.4.1.3 of

this Regulation 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, or other

characteristics which are visibly distinguishable, each representative

surface must be tested separately for stability in an area that represents a

random portion of the overall disturbed conditions of the site, utilizing the

appropriate test methods in Subsections 90.4.1.1 through Subsections

90.4.1.3 of this Regulation. Depending upon test method results, include

or eliminate each representative surface from the total size assessment of

the DIsTURBED SURFACE AREA(S).

90.4.1.1 Soil Crust Determination (The Drop Ball Test): Drop a steel ball with a

diameter of 15.9 millimeters (0.625 inches) and a mass ranging from 16-

17 grams from a distance of 30 centimeters (one foot) directly above the

soil surface. If blowsand is present, clear the blowsand from the surfaces

on which the soil crust test method is conducted. Blowsand is defined as

thin deposits of loose uncombined grains Covering less than 50% of an

OPEN AREA or VACANT LOT which have not originated from the

representative OPEN AREA or VACANT LOT surface being tested. If material

covers a visible cwst, which is not blowsand, apply the test method in

Subsection 90.4.1.3 (Determination Of Threshold Friction Velocity) of this

Regulation to the loose material to determine whether

the surface is stabilized.

(a) A sufficient crust is defined under the following conditions: once a

ball has been dropped according to Subsection 90.4.1.1 of this

Regulation, the ball does not sink into the surface, so that it is

partially or fully surrounded by loose grains and, upon removal of

the ball, the surface upon which it fell has not been pulverized, so

that loose grains are visible.

(b) Randomly select each representative DIsTURBED SURFACE for the

drop ball test by using a blind “over the shoulder” toss of a

throwable object (for example, a metal weight with survey tape

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attached). Using the point of fall as the lower left hand corner,

measure a 1-foot square area. Drop the ball three times within the

1-foot by 1-foot square survey area, using a consistent pattern

across the survey area. The survey area shall be considered to

have passed the Soil Crust Determination Test if at least two of the

three times the ball was dropped, the results met the criteria in

Subsection 90.4.1.1(a) of this Regulation. 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 criteria of Subsection 90.4.1 .1(a) of this Regulation

for all of the survey areas tested, then the site shall be considered

to have passed the Soil Crust Determination Test and shall be

considered sufficiently crusted.

(c) At any given site, the existence of a sufficient crust covering one

portion of the site may not represent the existerice or

protectiveness of a crust on another portion of the site. Repeat the

soil crust test as often as necessary on each portion of the overall

conditions of the site using the random selection method set forth

in Subsection 90.4.1.1(b) of this Regulation for an accurate

assessment.

90.4.1.2 Rock Test Method: The Rock Test Method, which is similar to

Subsection 90.4.1.3 (Determination Of Threshold Friction Velocity) of this

Regulation, 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 hardpacked 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 càver 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) Randomly select a 1 meter by 1 meter survey area within an area

that represents the general rock distribution on the surface (a I

meter by 1 meter area is slightly greater than a 3 foot by 3 foot

area). Use a blind “over the shoulder toss of a throwable object (for example, a metal weight with survey tape attached) to select

the survey surface and using the point of fall as the lower left hand

corner, measure a 1 meter by 1 meter survey 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.

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(b) Without moving any of the rocks, or other elements, examine the

survey area. Since rocks greater than 3/8 inch (1 cm) in diameter

are of interest, measure the diameter of some of the smaller rocks

to a get a sense of which rocks need to be considered.

(c) Mentally group the rocks greater than 3/8 inch (1cm) diameter lying

in the survey area into small, medium, and large size categories. 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) 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.

(e) 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) Divide the total rock area, calculated in Subsection 90.4.1.2(e) of

this Regulation, by two (to get frontal area). Divide the resulting

measurement

number by the size of the survey area (make sure the units of

match), and multiply by 100 for percent rock cover.

For example, the total rock area is 1,400 square centimeters, divide

meter

1,400 by 2 to get 700. Divide 700 by 10,000 (the survey area is 1

by 1 meter, which is 100 centimeters by 100 centimeters or

10,000 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) Select and mark-off two additional survey areas and repeat the

procedures described in Subsection 90.4.1.2(a) through

Subsection 90.4.1.2(f) of this Regulation. 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) If the average rock cover is greater than or equal to 20%, the

surface is stable. If the average rock cover is less than 20%, follow

the procedures in Subsection 90.4.1.2(i) of this Regulation.

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(i) If the average rock cover is less than 20%, the surface may or may

not be stable. Follow the procedures in Subsection 90.4.1.3

(Determination Of Threshold Friction Velocity) of this Regulation

and use the results from the rock test method as a correction (le.,

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

Threshold Friction Velocity (TFV) to be stable without accounting

for rock cover.

(j) After completing the procedures described in Subsection 90.4.1.2(i)

of this Regulation, use Table 2 of this Regulation 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.

90.4.1.3 Determination Of Threshold Friction Velocity (TFV): For DIsmRBED

SURFACE AREAS that are not crusted or vegetated, determine TFV

according to the following sieving field procedure (based on a 1952

laboratory procedure published by W. S. Chepil).

(a) 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 I

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 counterclockwise, 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

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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 I of

this Subsection, which provides a correlation between sieve

opening size and TFV.

Table 1. Determination Of Threshold Friction Velocity

Tyler Sieve No. ASTM 11 Opening TFV

Sieve No. (mm) (cm/s)

5 5 4 135

9 10 2 100

16 18 1 76

32 35 0.5 58

60 60 0.25 43

Collector Pan 30

(b) Collect at least three soil samples which represent random portions

of the overall 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 non-erodible 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 non-erodible elements using the following

procedure. For a more detailed description of this procedure, see

Subsection 90.4.1.2 (Rock Test Method) of this Regulation. 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:

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Eq. 1: (Average length) x (Average width) Average Dimensions.

Eq. 2: (Average Dimensions) x (Number of Elements) = Overhead Area.

Eq. 3: Overhead Area Of Group 1 + Overhead Area Of Group 2 (etc.) =

Total Overhead Area.

Eq. 4: Total Overhead Areal2 = Total Frontal Area.

Eq. 5: (Total Frontal Area/Survey Area) x 100 = Percent Cover Of Non

Erodible Elements.

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 of this Subsection 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 non-erodible elements.

Table 2. Correction Factors For Threshold Friction Velocity

Percent Cover Of Non-Erodible Elements 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

History: Initial adoption: June 22, 2000

Amended: November 20, 2001; December 17, 2002

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