PERMFILE116710

• Permit No: M1980183
• IBM Index Class Name: Permit File
• Doc Name: INFORMATION PAGE PAGE 2 OF 23
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• Archive: No

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AIR QUALITY IMPACT FROM BRANNAN PIT 29
I. INTRODUCTION
The Brannan Sand and Gravel Company plans to
mine and process sand and gravel at its Pit 29 which
is located east of Old Brighton Road in the north half
of the section north of the section in which
Henderson, Colorado is located. The property extends
east to Nome. It is a wet area on the east side of the
Platte River.
Brannan plans to mine 3000 tons per day during 167
spring, summer and autumn days. Thus, the annual
total production will be 500,000 tons. Overburden
will be used to build a berm around the area to shield it
from view from outside and to shield outside areas
from the noise of the operation. These berms will be
revegetated as rapidly as possible to reduce wind
erosion from both the berms and the protected area
within.
Operations at the pit will create dust, some of which
will remain airborne long enugh to be carried by the
wind to adjacent areas. The dust emissions to be
expected have been calculated and are reported
here.
II. EMISSIONS
The only significant pollutant emission expected
from operation of Pit 29 is particulate matter.
Emissions have been calculated using factors
approved by the Colorado State Air Pollution Control
Division. The operations to which the factors have
been applied are: 1) removal of overburden, 2) mining
and processing the sand and gravel, and 3) vehicle
traffic. Also, emissions from wind erosion of
disturbed areas have been calculated. Each of these
is discussed briefly in this section.
A. REMOVAL OF OVERBURDEN
It is anticipated that 20 acres of land will be
mined each year. The topsoil is 1.5 to 2 feet deep.
Additional overburden is 2 to 2.5 feet deep. In the
calculations a total overburden depth of 4.0 ft
has been used. The overburden will be removed
by scrapers and placed in berms around the
property or used to reclaim mined areas.
Disturbed areas will be revegetated as rapidly as
possible so that no more than 20 acres will be
subject to wind erosion at any time.
Emissions from the removal of overburden were
calculated by using a factor of 16 pounds of
particulate matter per hour of scraper operation.
The following formula applies
E = D
27 C S 2000
in which E is emission in tons; A is the area (A=
43,500 ft 2 X 20 X 43,600 ft );
d is the depth of overburden
in feet; C is the capacity of the scrapers in cubic
yards; D is the round trip distance in miles
traveled with each load; S is the scraper speed in
miles /hour, and EF is the emissions factor in Ibs
per scraper hour.
E= 872.000 X 4.4 X _ L X 9.2_`,z X 16
27 25 3.75 2000
E= 2.8 tons /year
B. MINING AND PROCESSING
The emissions factor for mining and processing
sand and gravel is 0.1 lb/ton of material
processed. This yields an annual emission of
E= 0.1 x 500,000 = 25.0 tons /year
2000
C. VEHICLE TRAVEL
The emissions factor for vehicle travel for speeds
under 30 miles per hour is given bythe following
formula:
EF= 1.81 s ( S ) 2 ( 365 - w ) N
30 365 X 4
in which EF is the emissionsfactor in pounds per
mile traveled; s is the silt content in percent of
the surface traveled; S is the vehicle speed in
miles per hour; w is the average number of days
per year with 0.01 in or more of precipitation;
and N is the number of wheels on the vehicle.
With s= 10 and w= 100, the formula reduces to
EF = 1.63 X 10 -4 S
*The caterpillar tractor is not a wheeled vehicle, but it
travels so slowly that emissions are very small.
Since the vehicles are to operate 167 days per
year, the annual production is 15.8 tons.
D. DISTURBED AREA EROSION
Wind erosion from exposed areas is given by the
universal soil loss equation
EF = a1KCL'V' (tons /acre year)
in which a is the portion of erosion losses that
can be measured as suspended particles; I is soil
erodibility in tons per acre year; K is a surface
roughness factor which varies from 0.5 for
deeply furrowed ground to 1.0 for a smooth
surface; C is a climatic factor which has a value
of 0.5 for this site; L' is an unsheltered width
factor which ranges from 0.7 for a disturbed area
1000 feet wide to 1.0 for an area 2000 feet wide,
and V' is a vegetative cover factor which ranges
from 0.0 for good, dense cover to 1.0 for no cover.
For Pit 29, the equation is
EF = 0.025 X 38 X 1.0 X 0.5 X 0.7 X 1.0=0.33
tons /acre year
For 20 acres, this yields 6.6 tons per year of
particulate emissions.
E. EMISSION CONTROLS
In a sand and gravel pit where materials are wet,
dust is controlled by the natural wetness of the
material. The emissions factor for mining and
processing takes account of this. Therefore,
although spray bars will be used on the
processing equipment, no control of the mining
or processing is assumed in calculating con -
trolled emissions.
The formula for calculating vehicular emissions
is based on a dry surface. Consequently,
controls, both natural and sprinkling, are
assumed in calculating emissions.
The emissions factor for removal of topsoil also is
based on working in soil that is naturally moist
but not wet. The overburden at Pit 29 will
probably be more moistthanthe soil on which the
factor was based, but it is assumed that no
controls will be used. Hence potential and
controlled emissions are equal.
Much of the disturbed area will be wet and not
subject to erosion. Also, the exposed overburden
will have a rough surface. Nonetheless, no
controls are assumed in calculating controlled
emissions from wind erosion.
F. SUMMARY
Calculated emissions from Pit 29 are
summarized in the table on the following page.
OPERATION
Overburden Removal
Mining and Processing
Vehicle Travel
Disturbed Area Erosion
2.8
25.0
15.8
6.6
TOTAL 50.2
TOTAL W/O
EROSION
POTENTIAL
(T /Y)
Emissions
(1 b /day) .
2.6 X 10
2.4 X 10 -3
176.4
2.0
0.6
0.3
9.8
189.1
METHOD OF
PERCENT
DAILY VEHICULAR EMISSIONS
Vehicle
Speed
Wheels
EF
Dist.
Type
(m /h)
(N)
(1 b /mi)
(mi /day)
Cat Loader
0.5
4
1.6 X 10 -3
16
D -8 Cat
0.25
4*
4.08 X 10 -4
4
Tractor Trailer
10
18
2.94
60
Pickup
10
4
0.65
3
Grease Truck
5
6
0.24
2,5
Mechanics Truck
10
4
0.65
0.5
Water Truck
10
10
1.63
6
TOTAL UNCONTROLLED
*The caterpillar tractor is not a wheeled vehicle, but it
travels so slowly that emissions are very small.
Since the vehicles are to operate 167 days per
year, the annual production is 15.8 tons.
D. DISTURBED AREA EROSION
Wind erosion from exposed areas is given by the
universal soil loss equation
EF = a1KCL'V' (tons /acre year)
in which a is the portion of erosion losses that
can be measured as suspended particles; I is soil
erodibility in tons per acre year; K is a surface
roughness factor which varies from 0.5 for
deeply furrowed ground to 1.0 for a smooth
surface; C is a climatic factor which has a value
of 0.5 for this site; L' is an unsheltered width
factor which ranges from 0.7 for a disturbed area
1000 feet wide to 1.0 for an area 2000 feet wide,
and V' is a vegetative cover factor which ranges
from 0.0 for good, dense cover to 1.0 for no cover.
For Pit 29, the equation is
EF = 0.025 X 38 X 1.0 X 0.5 X 0.7 X 1.0=0.33
tons /acre year
For 20 acres, this yields 6.6 tons per year of
particulate emissions.
E. EMISSION CONTROLS
In a sand and gravel pit where materials are wet,
dust is controlled by the natural wetness of the
material. The emissions factor for mining and
processing takes account of this. Therefore,
although spray bars will be used on the
processing equipment, no control of the mining
or processing is assumed in calculating con -
trolled emissions.
The formula for calculating vehicular emissions
is based on a dry surface. Consequently,
controls, both natural and sprinkling, are
assumed in calculating emissions.
The emissions factor for removal of topsoil also is
based on working in soil that is naturally moist
but not wet. The overburden at Pit 29 will
probably be more moistthanthe soil on which the
factor was based, but it is assumed that no
controls will be used. Hence potential and
controlled emissions are equal.
Much of the disturbed area will be wet and not
subject to erosion. Also, the exposed overburden
will have a rough surface. Nonetheless, no
controls are assumed in calculating controlled
emissions from wind erosion.
F. SUMMARY
Calculated emissions from Pit 29 are
summarized in the table on the following page.
OPERATION
Overburden Removal
Mining and Processing
Vehicle Travel
Disturbed Area Erosion
2.8
25.0
15.8
6.6
TOTAL 50.2
TOTAL W/O
EROSION
POTENTIAL
(T /Y)
Emissions
(1 b /day) .
2.6 X 10
2.4 X 10 -3
176.4
2.0
0.6
0.3
9.8
189.1
METHOD OF
PERCENT
EMISSIONS
CONTROL
CONTROL
FACTOR
None
0
16 lb /hr
None
0
0.1 lb/ton
Wetting
50
189.1 lb/day
None
0
0.33 T /acre yr
EMISSIONS
CONTROLLED
HOURLY RATE*
(T /Y)
W/O
2.8
0.53
25.0
4.72
7.9
1.49
6.6
1.12
42.3
7.86
35.7 6.74
ESTIMATED PRECIPITATION
Heaviest precipitation occurs during the spring and
summer months of April through June.
Jan. Feb. Mar. Apr. May June July Aug.
.60 .70 1.10 1.80 2.50 1.80 1.70 1.20
Sept. Oct. Nov. Dec. Annual Total
1.10 1.00 .70 .40 14.60
WINDS
ANNUAL The predominant wind direction at Pit 29 is from the
(g /s) south - southwest. The annual mean wind speed is
0.00 near 7 miles per hour (mph). Strongest winds
0.72 typically occur in March or April. The predominant
0.23 direction for wind speeds 25 mph or more is from the
0.19 northwest. The direction of daytime winds from 8
1.22 a.m. through 5 p.m. is highly variable. The direction
arc of greatest frequency for daytime winds is in the
quadrant from north through east.
*The hourly rate is the rate at which emissions occur
during working hours. For calculating maximum
(worst case) 24 -hour concentrations in the vicinity of
the site; hourly rates are assumed to exist for eight
hours, except that the disturbed area rate is assumed
to exist for 24 hours.
III. APPLICABLE REGULATIONS
Potential emissions will be 50.2 tons per year. This is
well under the 100 tons per year specified in Section
3.IV.D.4. of the Colorado Air Quality Control
Regulations. Hence that Section applies. It states
The Commission may only direct the Division to
issue an Emission Permit when the Commission
finds that one of the following conditions are
met:
That in the case of sources with potential
(uncontrolled) emissions of less than one-
hundred (100) tons per year of a single air
contaminant or which are otherwise exempt
from the requirements of Section IV.D.3.c. and
where the emissions would interfere with the
attainment or maintenance of national
ambient air quality standards (i.e., cause or
contribute to ambient concentrations which
exceed a national ambient air quality standard
in designated non - attainment areas), the
applicant will meet all other applicable
standards and regulations of the Commission
and that despite the emissions which will
result from the proposed new source or
modified source, reasonable further progress
toward the attainment of the national ambient
air quality standards is not impaired.
It is also pertinent that controlled emissions are 42.3
tons /year, 640 Ibs /day, and 62 Ibs /hour. The daily
and hourly rates occur during periods when wind
erosion is ocurring. Therefore, they are maximum
values. With these values, Section 3.IV.D.5.B.(vii)
exempts the operation from requiring offsets.
AMBIENT ANALYSIS, INC.
Al Morris
CLIMATIC INFORMATION RELATED TO PIT 29
Pit 29 is located in Adams County on the east
shoulder of the Platte River in the vicinity of 138th
Avenue and Highway 1 -76. It is in a zone of semi -arid
climate. Extreme warm weather in the summer
months produces daytime maxima temperatures in
the 90's. On a few morning in the winter, minima
temperatures go below 0 ° F.
TEMPERATURES
Mean monthly temperatures, based on comparative
historical records from Denver and Brighton, are as
follows:
Jan. Feb. Mar. Apr. May June July Aug.
28.4 31.8 36.5 47.0 56.5 65.5 72.0 70.6
Sept. Oct. Nov. Dec.
61.8 51.0 38.4 31.1
LOREN W. CROW
Certified Consulting Meteorologist
TRAFFIC AND ACCESS ANALYSIS
ACCESS ROADWAYS
All vehicular access is planned to be limited to one
Nome Street driveway location which will be
relocated from time to time during the phased
development of the project. Nome is a two -lane,
paved roadway having limited north /south
continuity between US 85 and CR 31 at 136th
Avenue. Present traffic activity on Nome is minimal
due to the low intensity of land uses which it serves.
Southbound Nome Street traffic is controlled by a
Stop sign at US 85.
US 85, which will serve as the project's access route
to and from the southwest, is a major divided four -
lane highway with a posted speed limit of 55 miles
per hour. Based on recent counts taken by the
Colorado Division of Highways, about 15,500
vehicles travel along US.85 in the vicinity of the site.
No other nearby roadways will be affected by the Pit
29 project.
TRAFFIC GENERATION AND DISTRIBUTION
The generation of traffic by Pit 29 should be
considered in a different light than atypical industrial
operation. First of all, very few employees are
involved in the gravel mining process and traffic
activity is uniformly distributed throughout the work
day. "Peak hour" traffic generation is therefore
virtually non - existent. Secondly, traffic consists of a
relatively small number of large vehicles, and such
activity is very dependent on factors such as weather
and construction scheduling. Because of these
characteristics, the operation will have only minimal
traffic impact. The Pit 29 operation is expected to
produce an estimated 500,000 tons of material per
year with a maximum daily production of 3000 tons.
This is equivalent to approximately 125 truck loads of
material on a maximum day.
The routing of Pit 29 vehicles dictates that all gravel
truck travel will be oriented to and from the south
along Nome Street and US 85. The only access
oriented to the north could be an occasional service
or employee vehicle.
CONCLUSIONS
The Pit 29 project will generate a maximum of 125
entering and 125 exiting vehicles on a maximum day
of production. All traffic will be destined to and from
the southwest via Nome Street and US 85. Both of
the affected roadways and their related traffic
controls are more than adequate to accommodate
this small increase in traffic activity.
LEIGH, SCOTT & CLEARY, INC.
Consulting Traffic Engineers
AIR QUA►LITY CLIMATOLOGY
& TRAFFIC ANALYSIS TEXT
Pa 21 of 23
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