United States Region IX Office EPA-909/9-81-001
Environmental Protection San Francisco, CA 94105 March 1981
Agency
*»EPA Monitoring and Modeling
Analyses of the Kennecott
Corporation Smelter in
McGill, Nevada
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This document is available to the public from the National
Technical Invormation Service, 5285 Port Royal Road, Springfield,
Virginia 22161.
This report was furnished to the Environmental Protection Agency
by PEDCo Environmental, Inc., Cincinnati, Ohio 45246,- in ful-
fillment of Contract No. 68-02-3173, T.O. 14. The contents of
this report are reproduced herein as received from PEDCo Environ-
mental. The opinions, findings, and conclusions expressed are
those of the author and not necessarily those of the Environmen-
tal Protection Agency. Mention of company or product names is
not to be considered as an endorsement by the Environmental Pro-
tection Agency.
Publication No. EPA-909/9-81-001
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mv
EPA
<\u\-
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SI'
Oo\
MONITORING AND MODELING ANALYSES
OF THE KENNECOTT CORPORATION
SMELTER IN McGILL, NEVADA
by
_r> PEDCo Environmental, Inc.
^ 11499 Chester Road
^ Cincinnati, Ohio 45246
oo
W
Contract No. 68-02-3173
Task No. 14
Project Officer
Linda Larson
Air Technical Branch
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION IX
SAN FRANCISCO, CALIFORNIA 94105
US EPA
Headquarters and Chemical Libraries
EPA West Bldg Room 3340 March 1981
Mailcode 3404T
1301 Constitution Ave NW
Washington DC 20004
202-566-0556
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EXECUTIVE SUMMARY
At the request of Region IX of the Environmental Protection
Agency (EPA), PEDCo Environmental, Inc., was hired to give an
independent assessment and review of the technical aspects of the
air quality analyses carried out at the Kennecott Smelter in
McGill, Nevada.
The primary objectives of this study are listed below:
0 To review the application of the Valley Model to the
Kennecott smelter at McGill, Nevada.
0 To review documents submitted by Kennecott Copper
Corporation to the EPA regarding the air quality impact
of emissions from the smelter.
° To develop an emission inventory of total suspended
particulate (TSP) that encompasses a 5-mile radius from
the smelter.
° To use dispersion modeling for determining the contri-
butions of sources to any violation of TSP air quality
standards.
0 To apply simple rollback methods for estimating the
extent of control necessary for reducing emissions
from the main smelter stack in order to attain the
primary and secondary TSP standards.
The main issue upon which all the above objectives focus is
whether particulate emissions from the main stack or fugitive TSP
emissions from the tailings pond are the principal contributor to
measured violations of the National Ambient Air Quality Standard
(NAAQS) for TSP. All available TSP air quality data collected
ii
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near the smelter were reviewed along with emission estimates for
all sources, meteorological data, and previous modeling method-
ologies and results; however, it could not be determined whether
the tailings pond or the main stack is the worst contributor.
Under various worst-case emission and meteorological scenarios,
either source can be shown to contribute the major portion of the
TSP concentration at different receptors. Modeling was used to
determine concentrations from the main stack over a 24-hour aver-
aging period. The maximum impact on air quality was estimated to
occur during stable atmospheric conditions coupled with light
windspeeds from the west and northwest at plume height. Under
these conditions, the plume disperses and travels toward the
mountains to the east of the plant. Lower maximum concentrations
from the main stack are estimated in the Steptoe Valley under
very unstable, light-wind conditions. Emissions from the tailing
pond have a maximum impact on air quality under condition of
generally high windspeec, persistent wind direction, and near
neutral atmospheric stability.
The latter conditions occur more frequently in the Steptoe
Valley indicating that emissions from the tailings pond contrib-
ute more frequently to the measured TSP violations of the NAAQS
in the valley than from the main stack. The supporting docu-
mentation, however, is somewhat inadequate to verify this conclu-
sion. The dispersion modeling conducted by EPA, Kennecott, and
PEDCo Environmental indicates no estimated violations of the
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NAAQS on a 24-hour or annual average basis due to individual or
combined emissions from the main stack and the tailings pond at
current monitoring si~es. When fugitive emission! from smelter
processes, the smelter boiler, and miscellaneous TSP sources are
included, however, some excursions of the TSP NAAQS are estimated
to occur near monitor sites.
Thus, this analysis concludes that an inadequate demonstra-
tion (and therefore, data base) has been made to support promul-
gation of control measures only for the main stack at the McGill
Smelter. A demonstration has not been made that is sufficiently
convincing that TSP violations are caused solely by the windblown
t
dust from the tailings( pond. This analysis does indicate higher
I
TSP concentrations when the smelter is operational than when it
is not. This may be due to increased particulatej emissions from
the main stack, the smelter fugitive emissions, cr both. Model-
ing results are inadequate, however, to clearly describe this
phenomenon.
v
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CONTENTS
Executive Summary
Figures
Tables
1.0 Introduction
1.1 Background
1.2 Smelter SIP History
2.0 Review of the Valley Model Applications
2.1 Appropriateness of the Valley Model
2.2 Verification of the Valley Modeling Results
2.3 Required Emission Reductions
2.4 Summary
3.0 Analysis of Kennecott's December 13, 1979, Submittal
3.1 Kennecott's November 1979 Research Program
3.2 Review of North American Weather Consultants
Study
3.3 Review of 1972 S02 Bubbler Data
3.4 Summary
4.0 Review of Kennecott's September 21, 1979, Submittal
Commenting on EPA's llOg Action
4.1 Comments of Kennecott Copper Corporation
4.2 Replies to EPA's Objections
4.3 Review of Kennecott's Technical Papers
5.0 Development of a Refined TSP Inventory and Related
Dispersion Modeling Analysis
5.1 Introduction
5.2 Emission Inventory
5.3 Modeling Methodology and Results
5.4 Summary
Page
ii
vii
viii
1-1
1-2
1-6
2-1
2-2
2-17
2-31
2-32
3-1
3-2
3-5
3-8
3-11
4-1
4-2
4-2
4-4
5-1
5-1
5-3
5-25
5-35
v
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CONTENTS (continued)
Page
6.0
Review of the Hydrodynamic Model
6-1
6.1
Model Overview
6-2
6.2
Model Evaluations
6-4
6.3
Applications to McGill
6-6
6.4
Summary and Conclusions
6-6
7.0
Statistical Analysis of Air Monitoring Data
7-1
7.1
Cumulative Frequency Distributions
7-2
7.2
Wind Direction vs. Violations
7-12
7.3
Summary
7-14
8.0
Conclusions
8-1
vi
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FIGURES
Number Page
1-1 Major Geographical Features of the Study Area 1-3
2-1 Windrose for Ely, Nevada, 1973-1976; All
Stabilities 2-27
2-2 Windrose for Ely, Nevada, 1973-1976; F-Stability 2-27
3-1 NWS Temperature Versus Height for Ely, Nevada,
September 16-19, 1979 3-9
5-1 Grid System and Major Geographical Features of
the Study Area 5-4
5-2 Equivalent Squares for Portions of the Kennecott
Tailings Pond 5-6
7-1 TSP Cumulative Frequency Distributions for the
McGill School Monitor: 8/76 to 5/79 7-3
7-2 TSP Cumulative Frequency Distributions for the
McGill School Monitor: 1975 to 1979 7-4
7-3 TSP Cumulative Frequency Distributions for the
North Flat Monitor: 11/77 to 12/79 7-6
7-4 TSP Cumulative Frequency Distributions for the
Townsite Monitor: 11/77 to 12/5 7-7
7-5 TSP Cumulative Frequency Distributions for the
South Flat Monitor: 11/77 to 12/79 7-8
7-6 Map Showing Resultant Wind Directions Associated
With .Each Excursion of the NAAQS From 1976
to 1979 7-13
VII
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TABLES
Number Page
1-1 Chronological Listing of SIP Strategies to
Control TSP at the McGill Copper Smelter 1-7
1-2 Nevada SIP Revisions 1-8
1-3 Deficiencies of 9/18/79 Revision 1-9
2-1 The Estimated and the Highest and Second
Highest Observed 24-H S02 Concentrations
in the Vicinity of Large Sources Located
in Complex Terrain 2-6
2-2 24-Hour Predicted TSP Concentrations (yg/m3)
Near McGill, Nevada Main Stack Contribution 2-10
2-3 24-Hour Predicted TSP Concentrations (yg/m3)
Near McGill, Nevada Fugitive Smelter
Emissions 2-11
2-4 24-Hour Predicted TSP Concentrations (vjg/m )
Near McGill, Nevada Tailings Pond Source 2-12
3
2-5 24-Hour Predicted TSP Concentrations (ug/m )
Near McGill, Nevada Sum of Stack andL Fugitives
and Tailings Pond and Background 2-13
2-6 Emission Factors Used by EPA and Kennecott 2-14
2-7 Updated Maximum 24-Hour TSP Concentrations
Caused by Emissions from the Mair. Stack,
yg/'m3 2-21
2-8 Updated Maximum 24-Hour TSP Concentrations
Caused by Emissions From the Smelter
Fugitives, yg/m3 2-22
2-9 Updated Maximum 24-Hour TSP Concentrations
Caused by Emissions From the Tailings Pond,
yg/m3 2-23
viii
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TABLES ' (continued)
Number Page
2-10 Updated Maximum 24-Hour TSP Concentrations
Caused by Emissions From the Main Stack, ^
Smelter Fugitives, and Tailings Pond, ug/m 2-24
2-11 Summary of Windspeed and Inversion Data Near
Plume Height (-350 Meters) of the McGill
Smelter Main Stack From Ely Airport Morning
Soundings (1960-1964) 2-30
5-1 Grid and Equivalent Square Location, Size,
and Mean Elevation 5-7
5-2 Particulate Emissions in the McGill Study Area
by Source Category 5-9
5-3 Particulate Emission Factors for Minor Stationary
Source Combustion Units 5-12
5-4 Variables Used to Estimate Emission Factors for
Fugitive Dust From Dirt and Gravel Roadways 5-17
5-5 Values Used to Estimate Emission Factors for
Windblown Fugitive Dust From Natural and
Agricultural Surfaces 5-20
5-6 Values Used to Estimate Factors for Windblown
Fugitive Dust From the Kennecott Tailings Pond 5-21
5-7 Windblown Fugitive Emissions From the Kennecott
Tailings Pond 5-22
5-8 Stack Parameters and Particulate Emission Rates
for the Main Stack and Small Boiler 5-23
5-9 Annual Average TSP Concentrations 5-28
5-10 Source Contributions to TSP Levels at the Five
Receptors With Highest Annual Average TSP
Concentrations 5-29
5-11 24-Hour TSP Concentrations in Valley Ring 1 5-31
7-1 Summary of 24-Hour Concentrations of TSP for
Monitors Located Near the McGill Smelter 7-9
7-2 Summary of Violations of the 24-Hour NAAQS for
TSP as Measured at Monitor Sites Located
Near the Kennecott Smelter at McGill, Nevada 7-11
ix
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ACKNOWLEDGEMENTS
PEDCo Environmental wishes to acknowledge the contributions
of the primary authors, Mr. George Schewe and Mr.: Les Ungers and
the helpful comments of the staff of the Environmental Protection
Agency, Region IX,especially Mr. Dennis Beauregarjd and the Project
Officer, Ms. Linda Larson. We also wish to thank; Mr. William
Miles of the Kennecott Corporation (McGill, Nevada) for his coop-
eration, for the facility tour, and for all the data he provided
to PEDCo. Additional.thanks is extended to Mr. Edward Burt of
the Source Receptor Analysis Branch, Environmental Protection
Agency, Research Triangle Park, North Carolina, for his guidance
on complex terrain modeling.
x
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SECTION 1
INTRODUCTION
Particulate emissions from the McGill smelter are 12 to 18
times the federally approved process limitations. Ambient TSP
concentrations were measured at Site No. 29-0560-022, which is
operated by the Department of Conservation and Natural Resources
(DCNR) , and at three semipermanent sites, which are operated by
Kennecott. These measurements show violations of the 24-hour
National Ambient Air Quality Standard (NAAQS) for total suspended
particulate (TSP) in the vicinity of the plant. Air quality
dispersion modeling conducted by Kennecott using the Valley
Model"'" shows the potential for violation of the primary standards
on nearby terrain based on particulate emissions from the main
smelter alone, but not at current monitor sites. Kennecott, on
the other hand, claims that the Valley Model overpredicts actual
ambient TSP concentration and contends the violations of the
NAAQS for TSP result from fugitive emissions from the tailings
pond.
The purpose of this report is to review the modeling results
and monitoring data provided by Kennecott, the DCNR, and the
Environmental Protection Agency (EPA) to determine if an adequate
data base can be found to substantiate and identify the source of
1-1
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emissions that contributes to worst-case anbient TSP concentra-
tions. This report also includes a revised particulate emission
inventory that is used as input for subsequent modeling.
1.1 BACKGROUND
Kennecott Minerals Corporation (KMC) operates a primary
copper facility in McGill, Nevada. The smelter is in the Steptoe
Valley about 16 km to the north-northeast of Zlv^ Nevada. The
Egan Range to the west and Duck Creek Range to the east rise 4000
ft above the valley floor at.the plant site (see[Figure 1-1).
The main facility lies at the base of the eastern side of the
valley with the tailings pond stretching almost all the way
across the valley 'to the western piedmont and mountains. Predomi-
nant winds are from the south at an annual average speed of about
5 m/sec. Precipitation in the valley averages only about 10 to
11 inches per year, while surrounding mountairitobs record higher
average precipitation. The Steptoe Valley range|s m width from
about 12 to 20 km. The valley width near the sm'elter is about 12
km and constricts the natural windflow. This cpnstriction tends
to cause a veering of the general wind direction's measured at the
Ely Airport located to the south-southwest compared with those
measured just north of the plant site at the North Flat. The
whole valley is characterized by lowlying scrub |bushes and crusty
surfaces with some farmland and pasture.
i
Valley floors in this region are about 600C ft above sea
level. This high elevation coupled with a clear, dry atmosphere
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EASTING, km
Figure 1-1. Major geographical features of the study area.
1-3
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is conducive to sharp night-time radiation coding that produces
inversion conditions in the valleys. A very pronounced drainage
wind sweeps down the valley in the early mcrning hours; under
strong to medium surface heating by the sun, the inversions and
drainage winds are generally dissipated by mid-morning. Gusty
winds from the south-southwest often exceed 9 to ,10 m sec ^ (15
to 16% of the time) and cause reentrainmenz of much of the
surface particulates from the 3000-acre tailings pond.
The following primary sources of particulate emissions are
attributable tc the McGill smelter:
° Main stack v
Height: ' 229 m
Diameter: 4.7 m
Gas velocity: 20.4 m sec
Elevation.: 6330 ft mean seal level (m.s.l.)
Location:- Universal Transverse Mercator (UTM) Coordinates
N 4364450 m
, E 692000 m
Maximum hourly TSP emissions -2100 lb/h
° Boiler stack
Height: 32 m
Diameter: 2.1 m
Gas velocity: 2.1 m sec
Elevation: 6305 m.s.l.
Location: UTM Coordinates
N 4364250 m
E 691940 m
Maximum hourly TSP emissions -120 lb/h
° Fugitive emissions from smelter operations
Vented process dust
Hauling and dumping input materials
Road dust
Located near main stack (center coordinates same)
Estimated by Kennecott to be 35 percent of main stack
emissions
1-4
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° Fugitive emissions from tailings pond
West of main facility 1 km
Over 3000 acres, 2100 acres active
Many small particles (<10 urn) subject to retrainment by
wind erosion
Some areas controlled by:
Water
Furrowing and water
Vegetation
Crusting
UTM Coordinates: N 4364700 m
(center of area) E 689500 m
Emissions vary (see Sections 2 and 5)
The Kennecott copper plant consists of two reverberatory
furnaces, one of which is shut down, and four Peirce-Smith Con-
verters, one of which is not used. Average production rates are
as follows:
° Blister copper capacity, 136 tons/day.
0 Concentrate processed, 544 tons/day.
The Nevada Department of Conservation and Natural Resources
operates a TSP high-volume sampler every sixth day at a site near
downtown McGill. The monitor is situated on the roof of the
McGill elementary school, about 1.6 km from the main stack.
Previous modeling experience and modeling guidance (e.g., Turner
1970) indicate that emissions from a stack as tall as the main
stack will generally have only a minimal impact on a receptor as
close as the McGill School except under extreme conditions (i.e.,
very unstable atmospheric conditions with windspeeds less than 2
to 3 m sec ^). Kennecott operates three TSP high-volume samplers
on approximately the same schedule as those on the State site.
Figure 1-1 shows the approximate location of all sites.
1-5
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1.2 SMELTER SIP HISTORY
On May 13, 1980, representatives of Kennecott Corporation
and the EPA met in Washington, D.C., to discuss possible solu-
tions to the issues separating the two regarding1 the air quality
impact of the McGill Smelter. The EPA1s presentation included a
chronological history of the State Implementation Plan for the
McGill Smelter. Table 1-1 summarizes EPA1s chronological listing.
Table 1-2 highlights the proposed revisions tc t'he Nevada SIP of
October 7 , 197 5, ar.d September 18, 1979 . Final ljy, Table 1-3 sum-
marizes the deficiencies noted by EPA concerning the proposed
September 18, 197 9, revisions. Based on a review of these tables,
it is evident that EPA has concluded that KMC's |strategy and
Nevada's proposed relaxation of the approved State Implementation
Plan (SIP) are inadequate to maintain the NAAQS. In their May
13 , 1980, bid for reconsideration of EPA1s promulgation of the
I
approved SIP, Kennecott also asked EPA to consider the economic
impact on McGill if the smelter were forced to close. No settle-
ment has been agreed upon to date by Kennecott and EPA.
The following sections will review and verify the applica-
tion of the Valley Model (Section 2), review North American
Weather Consultants Study (Section 3), review Kennecott's com-
ments on EPA llOg action, September 21, 1979' (Section 4), review
Hydrodynamic Model (Section 5), describe the TS? emission inven-
tory and subsequent modeling results (Section 6i) , and describe an
updated analysis of monitored data (Section 7).
1-6
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TABLE 1-1. CHRONOLOGICAL LISTING OF SIP STRATEGIES TO CONTROL
TSP AT THE McGILL COPPER SMELTER
Disapproval of the control strategy portion of Nevada's plan
for failure to demonstrate attainment and maintenance of both
primary and secondary particulate standards in the Nevada
Intrastate AQCR. Article 7.2 (Process Weight Regulation)
was approved.
Nevada submits a revision to Article 7.2.
EPA proposes to disapprove the relaxation of Article 7.2.
KMC submits control strategy to EPA.
KMC submits revised strategy to EPA.
Governor of Nevada issues a 110(g) suspension to suspend
Article 7.2.
EPA disapproves the 110(g) suspension for failure to demonstrate
that the SIP revision, upon which the suspension was issued,
would protect ambient standards.
Governor of Nevada submits a revision to Article 7.2, issues
a 110(g) suspension, and grants a 1-year variance.
EPA disapproves the 110(g) suspension since the suspension
was premature.
EPA disapproves the 10/7/76 TSP SIP revision.
1-7
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TABLE 1-2. NEVADA SIP REVISIONS
A. HIGHLIGHTS OF THE 10/7/76 REVISION
Specifies 1300 Ib/h value averaged over 24 hours
Regulates only solid particulate matter, but does not define solid
particulate matter.
No control strategy was submitted with the revision to Article 7.2.
No compliance tast method is specified.
Included a variance for 1 year (no action taken).
SO2 regulation deleted (EPA has deferred action or this).
B. HIGHLIGHTS OF THE 9/18/79 REVISION
1300 lb/h 1"rr= it on solid particulate matter averaged over 24 hours.
2100 lb/h 1 ¦"mit on,total particulate matter averacedr over 24 hours as
measured by EPA Method 5.
Includes a year variance.
Includes a revision to the SO^ regulation (Article 8,)
1-8
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TABLE 1-3. DEFICIENCIES OF 9/18/79 REVISION
Emission inventory is not accurate.
Air quality design value is incorrect.
750-ft stack not demonstrated to be GEP.
Control measures relied upon for the emission reductions are not
legally enforceable.
No compliance schedules have been submitted.
Solid particulate matter is not defined (same deficiency that
existed with the previous submission).
Use of Method 5 to determine compliance with a limit averaged over
a 24-hour period poses practical difficulties.
Attainment has not been demonstrated.
1-9
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REFERENCE FOR SECTION 1
1. Burt, E. Vi. Valley Model User's Guide. EPA-450/2-77-018,
U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina 27711. September 1977.
1-10
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SECTION 2
REVIEW OF THE VALLEY MODEL APPLICATIONS
On July 30, 1979, Kennecott submitted a report to EPA entitled
"An Analysis of Kennecott's Particulate Control Strategy at the
McGill, Nevada, Operations.""^ The purpose of this report was to
demonstrate the following:
0 That EPA could relax the particulate emission limita-
tions applied to the smelter stack without risking
violations of the ambient TSP standards.
0 That control of fugitive emissions from the tailings
pond would result in the attainment of the TSP stan-
dards.
The EPA requested further information and documentation regarding
a detailed emission inventory, an analysis of compliance costs,
and dispersion model estimates of ambient TSP concentrations in
areas where actual measurements have not been made.
Kennecott submitted an additional control strategy package
2
on August 7, 1979, showing attainment of the NAAQS for TSP. At
this point, EPA disapproved of using the Air Quality Display
3
Model for estimating TSP annual averages on the basis that the
model was designed for flat terrain and therefore results ob-
tained near the McGill Smelter would be inappropriate. For short-
term estimates of maximum concentration, Kennecott primarily used
4
the Hydrodynamic Model. The EPA also dismissed this model on the
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basis of too little documentation and inadequate treatment of the
complex flows that occur in and around complex terrain. At EPA's
request, Kennecott used the Valley Model to estimate concentra-
tions from the main stack, the smelter process fugitives, and the
tailings pond.0 On August 10, 1979, Kennecott submitted to EPA a
revised control strategy that essentially summarized the results
of applying the Valley Model. Both annual and 24-hour violations
of the TSP NAAQS were estimated for the Steptoe Valley and for
nearby terrain.
Throughout the various submissions to EPA over the past
year, Kennecott has maintained that the use of the Valley Model
for regulatory purposes was inappropriate because of simplistic
model assumptions and inadequate validation, especially at the
McGill Smelter. The EPA, however, points out that no other
models have been demonstrated to perform a~ the McGill Smelter
and that the Valley Model has been used correctly, i.e., as a
screening methodology to discern potential smelter impacts.
2.1 APPROPRIATENESS OF THE VALLEY MODEL
2.1.1 Past Guidance
In choosing the Valley Model for analyzing the potential
impact of particulate emissions from the smelter on ambient air
quality near the McGill Copper Smelter, Region IX was following
the policy established in previous EPA decisions. In the Guide-
line on Air Quality Models, two levels of modeling are con-
sidered: simple and refined. As stated in the Guideline:
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The first level consists of general, relatively simple
estimation techniques that provide conservative estimates of
the air quality impact of a specific source, or source
category. The purpose of such techniques is to eliminate
from further consideration those sources that clearly will
not cause or contribute to ambient concentrations in excess
of NAAQS or allowable concentration increments. Conversely,
these techniques can be used to identify those control
strategies that have the potential to meet NAAQS and allow-
able increments.
The Guideline,- however, does not identify any refined techniques
that are applicable to complex terrain. The Regional Workshops
7
on Air Quality Modeling: A Summary Report concludes that:
...an inadequate technical basis [exists] for recommending
refined models that can be generally used in complex terrain
situations. A need obviously exists for a complete mathe-
matical description of the physical processes involved. It
is, therefore, necessary to first require the application of
conservative screening techniques to determine the impact of
sources in complex terrain. If such techniques show a
potential problem, it is incumbent upon the source operator
to develop a specific on-site data base for use in a refined
model that has been shown to provide satisfactory estimates
in a similar situation.
7
The Summary Report continues:
The screening technique recommended for use in complex
terrain situations is the Valley Model. When the applicant
is planning to operate the source during times of stable
atmospheric flows, the Valley Model should be used with the
following worst case meteorological assumptions: (1) P-G
[Pasquill-Gifford] stability of "F"; (2) wind speed of 2.5
m/s; and (3) six hours of occurrence. The use of "F"
stability in Valley screening analyses has been challenged
as overly conservative because there may be increased
mechanical turbulence in rough terrain which the Pasquill-
Gif ford parameters do not consider, and at times the use of
"F" stability in the Valley Model has significantly over-
estimated observed concentrations. However, there is not
adequate justification for making such a change to the
screening technique since (1) there are cases where Valley
with "F" stability has proven to be a good predictor of
worst case concentrations, and (2) in some of the field
2-3
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studies performed in complex terrain the s-ability of the
atmosphere has been measured to be more stable than "F"
stability.
Based on EPA guidelines, the Valley Model is acceptable as a
screening tool for estimating ambient concentrations under worst-
case meteorolcgical and emission scenarios for sources located in
complex terrain. In attempting to apply ~he Hycrodynamic Model,
Kennecott did not develop an acceptable onsite data base (espe-
cially for the mountains to the east), nor did they obtain
approval from EPA to use the model. The EPA's disapproval
stemmed from a number of factors (discussed in Section 2), es-
pecially due to the Hydrodynamic Model's tendency to underpredict
concentrations in complex terrain. Finally, since the Hydro-
dynamic Model was disapproved, the Valley Model was the only
7
method available. The Summary Report reiterates the position of
the Guideline:^
In the absence of other models shown to be more appropriate,
the Valley Model is acceptable as the basis for selecting
emission limitations in complex terrain situations.
This guideline indicates that an alternative model must be
technically acceptable to EPA and be supported by a strong data
base. If the proposed model is found to be unacceptable based on
criteria in the EPA guidelines, the Valley Model should be used
even though it may have no supporting data base, in the vicinity
and involves very simplistic treatment of plume flow about the
terrain. Past studies summarized below indicate the performance
of the Valley Model in complex terrain.
2-4
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2.1.2 Previous Valley Model Applications
O
In a 1977 paper, E. Burt and H. Slater compared highest and
second-highest concentrations of SC>2 observed over a 24-hour
g
period at sites on elevated terrain near large emission sources.
All sites were at heights where the maximum air quality impact
was expected to occur. The paper indicates that at four of the
six sites the Valley Model estimates maximum 24-hour SC^ concen-
trations that are within a factor of two of the second-highest
observations (see Table 2-1). The paper also indicates, however,
that two of the sites were over 20 km downwind of the source, and
the estimated and measured concentrations at these distances
3
ranged from 15 to 36 yg/m of SC>2 • Because no models in flat or
complex terrain are expected to estimate dispersion at this
distance and these estimates are well below the 24-hour SC^ NAAQS
(365 pg/m^), they are not the best indicators of plume impact on
nearby terrain. The most similar site in terms of source/re-
ceptor distance to the McGill Smelter is the Jones Ranch receptor,
which is 2.9 km from the Miami Smelter. The Valley Model over-
estimated measured maximum 24-hour terrain impacts by a factor of
4.2 in 1974 and 3.2 in 1975.
A monitoring and modeling analysis undertaken by Ashland
9
Oil, Inc., and Systems Application, Inc., was designed to pro-
vide a data base for evaluating the performance of the Valley
Model. On a case-by-case basis, the Valley Model performed very
poorly in estimating observed SO2 concentrations, ranging from
2-5
-------
TABLE 2-1. THE ESTIMATED AND THE HIGHEST AND SECOND HIGHEST OBSERVED 24-H
S02 CONCENTRATIONS IN THE VICINITY OF LARGE SOURCES LOCATED IN COMPLEX TERRAIN
Concentration,
3
ug/m except as noted
Observed
Si te
Source
Distance from the
site to the source, km
Period
Estimated
Maximum
Second
highest
Crusher
Garfield
Smelter,
Utah
6.4
4/15/73-
1/31/75
2/1/74-
1/31/75
2480
2480
2564
6130
2473
3130
Lower Lake
Pt.
Garfield
Smelter,
Utah
4.5
3/8/75-
12/16/75
1/1-25/76
1.18 ppm
1.18 ppm
2.66 ppm
2.71 ppm
1.20 ppm
2.14 ppm
No. 106
Navajo
Gen Stn,
Arizona
22.8
10/1/74-
2/17/75
36
32
19
Nu. 107
Navajo
Gen Stn,
Ari zona
23.2
10/1/74-
2/17/75
25
30
15
Phelps Mine
Morenci
Smelter,
Arizona
4.7
1975
15490
2547
2416
Jones Ranch
Miami
Smelter,
Ari zona
2.9
1974
1975
8610
8610
2042
2642
1760
1548
-------
100 times too low to 5 times too high. When the highest concen-
tration estimated (1510 yg/m"^) is compared with the highest
observed (1131 pg/m^), however, the model estimates are about 1.4
times higher. Also of note is that the maximum concentration
actually occurred at a totally different receptor location from
that predicted by the model. Thus, had Ashland Oil conformed
with the derived emission limitations of the Valley Model, the
NAAQS may not have been violated to the extent measured. This
assumption is only conjecture, however. The alternative monitor-
ing methodology employed by Ashland Oil verified that violations
of the 24-hour standards do occur but not to the extent estimated
by the Valley Model. Ashland was able to refine the air quality
analysis by implementing a statistical methodology utilizing
available meteorological, emissions, and monitoring data.
Lee"^ compared selected results of the Valley Model with
observed concentrations. Reference is made to the evaluation by
Lantz, Hoffnogle, and Pahwa^ in which estimated and observed
pollutant concentrations were noted for the Navajo Power Plant
g
(Arizona) for stable cases (same data as used by Burt and Slater ).
Only the ratio of estimated to observed maximum 1-hour concentra-
tions was included in the analysis. For the Navajo study, the
ratio of estimated to observed ranged from 0.34 to 2.6. No 24-
hour comparisons were made.
12
Slowick and Pica compared the Valley Model with observed
concentrations at a sample site in Laurel Ridge, Pennsylvania,
near the Conemaugh Generating Station. Comparisons between
2-7
-------
estimated and observed 1-hour SC^ concentrations were made over a
period of 1 year. Researchers found that the ratio of estimated
to observed maximum 1-hour concentration was about 40 for the
highest concentration.
The evaluations of the Valley Model in ~hese studies tend
g
to agree with Burt ar.d Slater's 1977 summary which indicates
that (1) for estimating second highest 24-hour concentrations in
mountainous terrain, the Valley Model is usually within a factor
of two, and (2) the model is inappropriate for day-by-day or
hour-by-hour comparisons. In summary, several doncerns have
reappeared in the evaluations of the Valley Model. These include
plume passage through mountainous terrain, arbitrary placement of
i
the plume up to 10,meters from the terrain, andjan inadequate
description of the;windflow in complex terrain. | These technical
inadequacies are noted in the Valley Model user's guide, and are
recognized by the EPA and the general technicalicommunity as
deficiencies of the model for simulating physical reality. The
model has shown to,be conservative and straightforward to apply,
and is thus maintained by EPA as a screening tool and an acceptable
modeling techniques for complex terrain.
2.1.3 Application of the Valley Model at the McGill Smelter
2.1.3.1 Overview-r
The EPA and Kennecott initiated modeling of both the annual
average and 24-hour average TSP concentrations at the McGill
2-8
-------
Smelter. In model applications conducted with National Weather
Service (NWS) stability-wind rose data (STAR) from the Ely Air-
port, EPA found that concentrations at 13 receptors were esti-
mated to violate the annual NAAQS (75 ug/m"^), with a maximum
concentration of 284 yg/m^. At 12 of the 13 receptors, the
violations were caused by fugitive emissions from the smelter.
At the remaining receptor, emissions from both the main stack and
the smelter contributed to the violation. Measured violations of
the annual NAAQS do not occur at the monitor sites as predicted
by the Valley Model. Concentrations in excess of the NAAQS are
estimated because emissions from all sources are much higher than
those that actually occurred annually.
Results of the 24-hour average modeling conducted by Kenne-
cott show that emissions from the main stack alone violated the
primary TSP standard of 260 pg/m"^ under E and F stability condi-
tions. These critical receptors were located in the eastern
mountains 1.5 km from the plant. Emissions from the main stack
are also estimated to violate secondary TSP standards under A
stability at various sites in the valley. Tables 2-2 through
2-5 show the estimated concentrations caused by emissions from
the main stack and fugitive emissions from the smelter and tail-
ings pond for each wind direction and stability condition,
regardless of downwind direction. No violations were estimated
to have been caused by fugitive emissions from the tailings pond
(see Table 2-3).
2-9
-------
TABLE 2-2. 24-HOUR PREDICTED TSP CONCENTRATIONS
(yg/m3) NEAR McGILL, NEVADA
MAIN STACK CONTRIBUTION
Stability Class
Radial direction
from smelter
A
B
C
D
E
F
N
190*
24
11
0.8
0
0
NNE
175*
24
11
0.8
0
0
NE
142
24
11
0.8
241*
380*
ENE
201*
24
11
0.8
416*
633*
E
190* '
24
11
0.8
781*
1760*
ESE
201*
24
11
0.8
523*
1039*
SE
| 142
24
11
0.8
566*
1381*
SSE
175*
24
11
0.8
¦ 582*
897*
S
190*
24
11
0.8
171*
335*
SSW
136
24
11
0.8
0
0
SW
1 94*
24
11
0.8
0
0
WSW
201* ¦
24
11
0.8
0
0
u
190* .
24
11
0.8
0
0
WNW
201*' '
24
11
0.8
0
0
NW
194*
24
n
0.8
0
0
NNW
136
24
n
0.8
0
0
These 24-hour TSP concentrations were predicted by the Valley Model, based
on TSP emissions of 2100 lb/h from the main stack at Kennecott. For each
stability class, the highest concentration (yg/m^) along jeach radial is shown.
Predicted violations of the 24-hour NAAQS, both primary (260 yg/m3) and secon-
dary (150 yg/m3) standards,' are shown with an asterisk. 'These concentrations
ignore any background contribution.
SOURCE: Analysis of the,Kennecott Copper, McGill, Nevadc, Particulate Control
Strategy, EPA Region memorandum dated August 20-j 1979.
2-10
-------
TABLE 2-3. 24-HOUR PREDICTED TSP CONCENTRATIONS
(pg/m3) NEAR McGILL, NEVADA
FUGITIVE SMELTER EMISSIONS
Stability Class
Radial direction
from smelter
A
B
C
D
E
F
N
61
75
83
6
39
54
NNE
56
78
85
6
363*
435*
NE
60
81
86
7
*
00
850*
ENE
44
66
75
5
542*
714*
E
51
75
83
6
589*
758*
ESE
44
66
74
5
481*
633*
SE
61
81
86
7
614*
758*
SSE
56
78
85
6
633*
798*
S
62
75
83
6
635*
818*
SSW
92
90
88
10
316*
397*
SW
60
57
68
5
41
16
WSW
44
66
75
5
13
1
w
52
75
83
6
21
6
WNW
44
66
68
5
10
1
NW
59
56
68
5
11
1
NNW
91
90
87
10
18
4
These 24-hour TSP concentrations were predicted by the Valley Model, based
on TSP enissions of 735 lb/h (i.e., 35% of the main stack emissions). For each
stability class, the highest concentration (pg/m3) along each radial is shown.
Predicted violations of the 24-hour NAAQS, both primary (260 yg/m3) and secon-
dary (150 yg/m3) standards, are shown with an asterisk. These concentrations
ignore any background contribution.
SOURCE: Analysis of the Kennecott Copper, McGill, Nevada Particulate Control
Strategy, EPA Region memorandum dated August 20, 1979.
2-11
-------
TABLE 2-4. 24-HOUR PREDICTED TSP CONCENTRATIONS
(yg/m3) NEAR McGILL, NEVADA
TAILINGS POND SOURCE
Stability Class
Radial direction
from smelter
A
B
C
D
E
F
N
0
0.8
2
36.9
0
0
NNE
o !
0.8
2
37.1
0
0
NE
0
0.8
2
41.9
0
0
ENE
0
0.8
2
31.8
0
0
E
0
0.9
2
38. 5
0
0
ESE
0
0.9
2
30.6
0
0
SE
0
0.8
2
40.4
0
0
SSE
c
0.8
2
37.7
0
0
S
0
0.8
2
36.7
0
0
SSW
0
0.7
2
43.0
0
0
SW
0
0.8
2
48.6
0
0
WSW
0
0.8
2
42.4
0
0
W
0
0.9
2
51.8
0
0
WNW
0
0.8
2
39.5
0
0
NW
0
0.8
2
50.4
0
0
NNW
0
0.8
2
42.1
0
0
These 24-hour concentrations were predicted by the Val'ey Model, based on TSP
emissions (emissions vary with wind speed and were estimated from measurements
at 10 mph and extrapolated to 30 mph) from the tailings pond at Kennecott.
For each stability class, the highest concentration (ug/m^) along each radial
is shown. No violations of the 24-hour TSP NAAQS are predicted. These con-
centration ignore any background contribution.
SOURCE: Analysis of the Kennecott Copper, McGill, Nevada Particulate Control
Strategy, IPA Region memorandum dated Augus" 20, T979.
2-12
-------
TABLE 2-5. 24-HOUR PREDICTED TSP CONCENTRATIONS
(vjg/m3) NEARMcGill, NEVADA
SUM OF STACK AND FUGITIVES AND TAILINGS POND AND BACKGROUND
Stabi1 i ty Class
Radial direction
from smelter
A
B
C
D
E
F
N
266*
100
105
62
64
79
NNE
256*
103
110
62
388*
460*
NE
228*
106
112
67
712*
875*
ENE
270*
91
10.1
58
567*
740*
E
266*
100
109
60
871*
1888*
ESE
269*
91
100
57
569*
1167*
SE
228
106
111
65
657*
1510*
SSE
256
103
110
63
658*
965*
S
267*
100
IOC
62
660*
841*
SSW
190*
115
113
68
341*
422*
sw
258*
82
93
74
66
41
wsw
270*
91
100
68
38
26
w
267*
100
108
83
46
31
WNW
270*
91
100
65
35
26
NW
258*
81
93
75
36
26
NNW
190*
115
112
67
43
32
These 24-hour TSP concentrations were predicted by the Valley Model. For each
stability class, the highest concentration (pg/m3) along each radial is shown.
Predicted violations of the 24-hour NAAQS, both primary (260 pg/m3) and secon-
dary (150 ug/m3) standards, are shown with an asterisk. These concentrations
ignore any background contribution.
SOURCE: Analysis of i:he Kennecott Copper, McGill, Nevada Particulate Control
Strategy, EPA Region memorandum dated August 20, 1979.
2-13
-------
2.1.3.2 Model Inputs—
Kennecott provided emission estimates and stack parameters
for modeling at the McGill Smelter. Section 1 describes all the
stack and fugitive source parameters. Previous source testing
data for the main stack were used to estimate the TSP emissions.
Kennecott estimated the maximum TSP emissions to, be 265 g/s (2100
lb/h). Fugitive emissions from the smelter complex were estimated
to be about 35 percent of the main stack emissions, or 92.7 g/s
(7 35 lb/h). The rate of emissions from the tailings pond was
calculated by measuring the TSP very near the pcnd at a wind-
speed of 10 m/s, by estimating the plume height and width, and by
back-calculating via Gaussian assumptions. At 4.47 m/s (10 mph),
the emission rate is estimated to be 16.38 g/s (130 lb/h) and at
13.4 m/s (30 mph) ,.1261 g/s (10, 000 lb/h) (Kenr.ejcott extrapolated
results) . Table 2-6 presents emission factors ujsed in the EPA
and Kennecott 24-h Valley modeling. The factors; are broken down
according to stability and windspeed class. The fugitive emis-
sion factors are slightly less than those calculated by using the
735 lb/h rate. Emissions factors for B stability at a windspeed
of 4.47 m/s (10 mph) are assumed to be the ones Kennecott used
for their annual average estimates.
TABLE 2-6. EMISSION FACTORS USED BY EPA AND KENNECOTT
(g/s except as noted)
Stability class
Windspeed, m/s
A
2.0
B
4.47
C
5.0
D
13.41;
E
2.4
F
2.5
Emission sources
Main stack
264.0
264.0
264.0
264.0
264.0
264.0
Smelter
90.21
90.21
90.21
90.21
90.21
90.21
Tailings
0.0
16.38
28.38
1261.0
0.0
0.0
2-14
-------
Other inputs for the Valley Model include the receptor grid
and meteorological data base for determining the impact of the
13
worst-case condition. A simplified model (PTMAX )was used as a
screening procedure to locate receptors at the points of maximum
concentration under the expected worst-case conditions in regard
to emissions from the main stack (i.e., F stability and 2.5 m/s
winds). Under these conditions, the final plume rise from the
main stack was about 340 m (1130 ft), which was added to the
stack base elevation (6330 m.s.l.). Under E and F stabilities,
the plume was expected to disperse very little over the first few
kilometers of downwind travel and thus have an impact only on
nearby terrain at this height. The maximum concentration was
estimated 1.5 km due east of the plant at an elevation of 7450 ft
m.s.l. After this location is determined for the Valley Model,
other receptors are locked into various preassigned positions in
approximate radials ranging from about 0.7 to 6 km around the
plant. Elevations are input for each receptor and source. The
main stack is situated at the center of the coordinate system and
is treated as a point source. Fugitive emissions from the
smelter are treated as a square (305-m) area source centered on
the coordinate system, with a fixed release height of 45 m. The
tailings pond is a large square area source (=2900 m on a side)
situated 3 km to the west with a 15-m fixed-release height. In
all cases in the Valley Model, area source dispersion is treated
as if the plume is terrain-following, i.e., is located in flat
terrain.
2-15
-------
National Weather Service data from Ely, Nevada, in the STAR
format were used to estimate the annual average concentrations
1973 to 1976. Annual average temperatures, pressures, and mixing
heights are noi specified in any of the EPA or Kennecott reports
submitted to PEDCo. Short-term modeling estimates of these
parameters found in EPA files are input as conservative annual
meteorological data.
For the 24-hour analyses, the Valley Modellguidance is
followed in selecting meteorological parameters | for the worst
case, i.e., F stability, 2.5-m/s winds from zheiwest toward the
]
mountains. Table 2-6 summarizes other stabilities and associated
l
worst-case windspeeds used in this analysis. Thie average monthly
high temperature is estimated to be 288K (59°F) ,j and the worst-
case daily mixing height, 500 m. In addition to the grid of
receptors just mentioned, a grid out to about 25 km is also used
for the annual average estimates to prevent the joccurrence of
significant impacts further downwind.
2.1.3.3 Model Assumptions--
The following basic assumptions of the Vallley Model were
used in this analysis: the main stack gases have buoyancy and
rise beyond the height of the physical stack height; area sources
are treated as if they are located in flat terrain; stack sources
may impact on nearby mountains; and source contributions to
receptors are additive. Application of the Valljey Model for 24-
hour average concentration estimates also assumes that the
2-16
-------
meteorological conditions will occur for at least 6 hours. Since
no onsite meteorological data are available for the 300-m level
(i.e., above the ground), the assumption is made that worst-case
meteorology does occur or can occur at sometime over a 1-year
period. (See Section 2.2.3.)
2.2 VERIFICATION OF THE VALLEY MODELING RESULTS
2.2.1 Overview
PEDCo was able to verify most of the 24-hour TSP concentra-
tion estimates obtained by EPA and Kennecott. Concentrations
similar to previous Valley simulations were obtained through the
use of like parameters, sources, meteorology, and model options
(see Appendix A). Since PEDCo performed an independent screening
analysis of the main stack and set up a receptor grid based on
this analysis, the receptor grid is slightly different. The key
feature of EPA's grid, however, was verified: the maximum impact
on air quality is expected to take place in the mountains to the
east of the plant at final plume height under F stability and 2.5
m/s windspeed.
2.2.2 PEDCo Verification
In order to test the calculations obtained by EPA and
Kennecott in previous Valley Model applications, PEDCo obtained
all input data as described in Section 2.1.3. A slightly dif-
ferent receptor grid is based on input from an independent
screening and worst-case impact analysis. Emissions from the
2-17
-------
main stack are estimated to have the greatest irr.pact 1.61 km to
the southeast 1.135 degrees) of the smelter. Even though the grid
spacing of the receptors is slightly different, PEDCo's analysis
results in concentration estimates almost identical to those
presented in Tables 2-2 through 2-5. The minor differences
between the results reported probably arise frorr: subjective
readings of topographical maps, variations in distance from the
plant, and different screening results. Therefore, using es-
sentially identical inputs to the Valley Model, PEDCo reproduced
l
the TSP estimates obtained by EPA and Kennecott.
2.2.3 Update and 1 Revision to Smelter Modeling
Some changes and refinements in emission parameters and
source characterization results were added to the base case
Valley results described in the previous sections. After pre-
vious Method 5 stack data on emissions from the smelter main
stack were reviewed, the following changes were implemented:
Main stack - Exit velocity changed from 20L4 to 21.2 m/s
Main stack - Emissions reduced from 2100 to 2055 lb/h
Smelter fugitives - Emissions reduced from 735 to 710 lb/h
The only meteorological parameters changed were the 24-hour
average temperature (from 288 to 290K) and the windspeed associ-
ated with a worst-case impact for A stability (based on PEDCo's
PTMAX screening analysis of the main stack, the change was from
2.5 to 2.0 m/s;-. Fcr the main stack, the screening analysis also
indicated windspeeds of 5, 7, and 10 m/s as critical for B, C,
2-18
-------
and D stabilities, respectively; however, these values are pre-
empted because the only tailings pond emission factors available
are for windspeeds of 4.47, 5.0, and 10.0 m/s.
Based on these revised parameters, some slightly modified
tailings pond coordinates, and the independently derived receptor
grid, the Valley Model was rerun for both the annual and 24-hour
concentration estimates. Also, for the annual average simula-
tions a larger grid of receptors was again included in a separate
run. The maximum concentration from this latter large grid
3
analysis is 50 pg/m at about 5 km to the north-northeast of the
plant. Since the smaller grid covers this region, no further
results of this large-scale analysis will be discussed.
On the small grid, 14 violations of the annual average pri-
3
mary NAAQS (75 pg/m ) are estimated. The arithmetically averaged
Valley Model estimates must be compared with the NAAQS geometric
14
mean. If a standard geometric deviation of 1.6 is assumed and
the distribution of all concentrations is assumed to be log-
normal, the following relationship from Larsen15 may be used for
the conversion from a geometric standard to an arithmetic stan-
dard :
2
m = mg [exp (0.6 In sg)]
where m = the arithmetic mean NAAQS
mg = 75 pg/m^
sg = 1.60 (average of several stations in nearby Utah
counties)14
2-19
-------
Thus, the standard may now be expressed as 84 yg/m^, and one po-
tential violation of the NAAQS is eliminated. One of the remain-
ing 13 may be attributed to the main stack (72 percent of total).
The 13 receptors are located as follows: 1 is to the southeast
at 1.6 km from the main stack (at the point the main stack is
expected to have maximum impact for 24-hour estimates), 9 are
situated clockwise from the north to south at 0.6 to 0.9 km, 2
are located to the north-northeast at 1.3 km, and 1 is located
northeast at 1.6 km (in the valley). No monitors are located at
any of these sites. Estimated annual TSP concentrations recorded
at 12 of the receptors range from 88 to 16C- yg/ir.^; the maximum
3
estimate of 3 53 yg/m was recorded at the remaining receptor,
0.67 km to the northeast of the plant. As with the previous
analysis, these estimates are conservative since short-term par-
ticulate emissions are used rather than annual averages.
. ' I
For short-term 24-hour concentrations, the Valley Model is
used to estimate concentrations from the main stack, the smelter
fugitives, and the tailings pond for stabilities A through F.
Tables 2-7 through 2-10 summarize the results of these calcula-
tions. Maximum concentrations are presented for each wind direc-
tion and stability iregardless of downwind distance. For esti-
mates in which B, C, and D stability classes were used, little
difference is detected in estimates for various wind directions
and receptors; thus', only the four cardinal directions or a few
other receptors are displayed. No violations of the primary
NAAQS of 260 yg/m are noted for stabilities A through D; although
2-20
-------
TABLE 2-7. UPDATED MAXIMUM 24-HOUR TSP CONCENTRATIONS
CAUSED BY EMISSIONS FROM THE MAIN STACK,
(pg/m3 except as noted)
Stability class
Windspeed, m/s
A
2.5
Ba
4.47
ca
5
D3
13.41
E
2.5
F
2.5
Radial direction
from smelter
N
128
24
10
0.8
0
0
NNE
118
0
0
NE
99
276
434
ENE
147
565
864
E
128
24
10
0.8
1214
1762
ESE
147
607
963
SE
99
885
1789
SSE
118
640
976
S
128
24
10
0.8
140
265
SSW
118
0
0
sw
WSW
160
147
0
0
0
0
w
128
24
10
0.8
0
0
WNW
NW
147
160
0
0
0
0
NNW
118
0
0
a B, C, and D stabilities were only partially modeled since concentrations
appeared to be independent of wind direction.
2-21
-------
TABLE 2-8. UPDATED MAXIMUM 24-HOUR TSP CONCENTRATIONS
CAUSED BY EMISSIONS FROM THE SMELTER FUGITIVES,
(yg/m3 except as noted)
Stability class
Wind speed, m/s
A
2.5
Ba
4.47
ca
5
D5
13.41
E
2.5
F
2.5
Radial direction
from smelter
N
47
81
88
8
33
19
NNE
50
169
271
NE
57
724
865
ENE
42
600
766
E
47
81
88
8
624
782
ESE
42
562
717
SE
57
638
762
SSE
.50
649
799
S
47
81
88
8
685
859
SSW
84
128
119
SW
56
15
0
WSW
42
12
0.9
w
47
81
88
8
15
1.5
WNW
NW
NNW
42
34
84
10
14
21
0.6
1.1
3.5
a B, C, and D stabilities were only partially modeled s:nce concentrations
appeared to be independent of wind direction.
2-22
-------
TABLE 2-9. UPDATED MAXIMUM 24-HOUR TSP CONCENTRATIONS
CAUSED BY EMISSIONS FROM THE TAILINGS POND,
(yq/m3 except as noted)
Stabi1i ty class
Wind speed, m/s
A
2.5
Ba
4.47
Ca
5
Da
13.41
E
2.5
F
2.5
Radial direction
from smelter
0
0.2
0.4
17
N
0
0
NNE
0
0
NE
1.0
0
0
ENE
0.4
1.0
0
0
E
0.4
1.0
31
0
0
ESE
0.4
22
0
0
SE
0
0
SSE
0.1
0
0
S
0.2
0.4
18
0
0
SSW
0.3
0.7
28
0
0
SW
0.4
1.1
30
0
0
WSW
0.7
1. 5
24
0
0
W
0.9
2.1
41
0
0
WNW
0.9
1.9
0
0
NW
0.5
1.2
31
0
0
NNW
0.3
0.8
28
0
0
Only selected modeling was performed with results indicating no potential
violations. Receptors not modeled are expected to be equal to or less than
indicated value.
2-23
-------
TABLE 2-10. JPDATED MAXIMUM 24-HOUR TSP CONCENTRATIONS
CAUSED BY EMISSIONS FROM THE MAIN STACK,
SHELTER FUGITIVES, AND TAILINGS POND,
(yg/m^ except as noted)
Stabi1ity class
Wind speed, m/s
A
Bb
4.47
Cb
5
Dd
13.41
E
2.5
F
2.5
Radial direction
from smelter
ri
199
106
113
51
58
44
NNE
183
194
296
NE
158
749
890
ENE
213
625
915
E
199
107
114
64
1279
1849
ESE
'213
663
1038
SE
. 158
975
1914
SSE
"83
688
1040
S
"99
106
113
51
710
884
SSW
"67
57
153
145
SW
219
55
40
25
wsw
213
37
26
w
WNW
"99
213
107
114
75
40
35
27
26
NW
219
56
39
26
NNW
167
56
46
29
a Includes background concentration of 25 yg/rn^.
b B, C, and D stabilities were only partially modeled sirce concentrations
are only slightly dependent on wind direction and no y/iolations are ex-
pected.
2-24
-------
secondary standard violations are estimated under A stability for
total concentrations. Violations detected on nearby terrain are
noted for stabilities E and F. Table 2-7 shows that emissions
from the main stack contribute to estimated violations under E
and F stability, at receptors on the terrain to the east of the
plant. The main stack emissions also contribute to the estimated
3
exceedances of the secondary NAAQS (150 ug/m ) under A stability
at receptors in the valley. Fugitive emissions from the smelter
also contribute to violations of the secondary NAAQS at the same
receptors as the main stack under A stability, but at different
receptors under E and F stability conditions (downwind distances
not shown). Emissions from the tailings pond are not estimated
to cause any violations of the 24-hour standard under the assumed
conditions. No monitors are located at sites estimated to re-
ceive maximum concentrations of emissions primarily from the main
stack. This indicates that monitors should be located in the
vicinity of these maximum impact areas to detect maximum concen-
trations. The McGill School Monitor (State Site 29-0560-002),
however, lies about 1.6 km to the south-southeast of the main
stack (0.8 km from potential fugitive emissions) and is posi-
tioned such that maximum 24-hour concentrations due to the com-
bined smelter fugitive and the main stack emissions may be moni-
tored. Upon examination of the STAR data gathered at the Ely
Airport weather station from 1973 to 1976, it was found that
conditions conducive to a maximum impact at the McGill monitor as
a result of emissions from the main stack (A stability, north to
-------
windspeed) occurred only over one 3-hour period in 4 years.
Similarly, conditions that may lead to a maximum impact at the
McGill site as a result of fugitive emissions from sources at the
plant (F stability, north to east-northeast winds, and 1- to 3-
m/s windspeeds) occurred for thirty-two 3-hour periods (0.74
percent of total). Thus, the Valley Model indicates that the
fugitive emissions from the smelter contribute rr.ost frequently to
potential violations of the 24-hour TSP standard at the McGill
school monitor.
A basic consideration in applying tha Valley Model is
whether the wcrst-case assumptions are reasonable, i.e., does the
model consider a worst-case concentration estimate based on a
reasonable combination of representative meteorology, source
characterization, plume rise, and plume dispersion? This con-
sideration is especially important when one estimates the maximum
impact and location'of such impact in regard to emissions from
the main stack. All other sources modeled thus far are based on
receptors in flat terrain because there is little evidence to
treat area source dispersion in complex terrain any differently.
On the other hand, point sources under stable, light-wind,
limited mixing conditions tend to emit plumes that often level
off after achieving final plume height and flow toward, around,
or over downwind e'levated terrain in ribbons or sheets.^ Thus,
the Valley Model is applied to the main stack at McGill with this
I "
type of worst-case scenario in mind. The wind rose for Ely,
Nevada, in Figure 2-1 shows that winds from the southwest through
2-26
-------
Figure 2-1. Windrose for Ely, Nevada, 1973-1976;
all stabilities.
1-3
KŁT: (m/jec)
Figure 2-2. Windrose for Ely, Nevada, 1973-1976;
F-stabi1i ty.
-------
north occur about 37.2 percent in a given year. Since the National
Weather Service readings are only taken every 3 hours and are not
3-hour averages but rather 1-minute averages, the wind rose
derived from the airport is not necessarily suited for modeling.
These roses, however, are indicative of the atmospheric condi-
tions near the plants and provide at least a continuous, though
limited, record. Further examination of the Ely, Nevada, annual
wind rose indicates that for the directions just discussed (SW,
WSW, W, WNW, NW, NNW, N), windspeeds of 1 to 3 m/s occur about
3.5 percent of thei time. The worst-case estimates for the main
stack, however, occur under light windspeed, F stability condi-
tions. Figure 2-2 shows a similar wind rose, but only for F
stability conditions. When only considering winds from the W,
WNW, NW, and NNW wind directions toward the terrain at windspeeds
of 1 to 3 m/s during F-stability conditions occur about 1.0
percent of the time. Thus, the surface-based observations
demonstrate the possibility of the occurrence of conditions
conducive to plume dispersion toward the eastern mountains.
The main stack' is 229 m tall. The windspeeds and directions
at the surface may be very different from these at plume height
(under F stability, 2.5 m/s, the final plume height approximated
by the Valley Model .is about 345 m above the stack base) . Thus,
the extrapolation of surface data to plume height is at best an
estimate of the atmospheric conditions affecting dispersion from
the main stack. A better indicator is found by examining upper
air summaries taken from twice-a-day soundings at the Ely airport.
2-28
-------
The early morning soundings (0400 local standard time [l.s.t.])
are best suited to characterizing the winds at stack height.
Table 2-11, which summarizes these conditions, is derived from
Inversions Study, Percentage Frequency of Temperature, Relative
Humidity, and Wind (Seasonal and Annual). Because only the
four cardinal directions are given in the report, the winds from
the west are chosen as the most representative of conditions
conducive to plume impaction. Again, these are only indicators
of how often these conditions may occur.
In summary, the results EPA and Kennecott obtained by using
the Valley Model are verified in an updated and independent mod-
eling analysis performed by PEDCo. The analysis indicates that
the main stack has a significant impact on terrain to the east of
the smelter under meteorological conditions that occur about 1.3
percent of the time (about 114 hours) at the plume height. Since
this percentage is expressed as a portion of the total number of
hours in a frequency distribution, no specific information on
the number of sequential hours (persistence) with these conditions
is given. Very limited monitoring data, however, exist to con-
clusively support the occurrence of high concentrations on the
terrain. Under the assumed conditions in the analysis, the
Valley Model indicates that emissions from the tailings pond have
very little impact. The results also demonstrate, however, the
potential high impact of the fugitive emissions from the smelter
on receptors within 2 km of the smelter. This conclusion is
supported by monitored excursions of the 24-hour TSP NAAQS at
2-29
-------
TABLE 2-11. SUMMARY OF WINDSPEED AND INVERSION DATA NEAR PLUME
HEIGHT (-350 METERS) OF THE McGILL SMELTER MAIN STACK FROM
ELY AIRPORT MORNING SOUNDINGS (1960-1964)
Inversion
conditions
Wind-
speed,
m/s
Wind
direction
(0)
Season
% frequency of
Occurrence3
Base height, m
Thickness, m
Any inversion
2.5-5.0
W
Yearly
4.5
Surface to 100
251-500
2.5-5.0
w
Yearly
1.3
Surface to 100
251-500
2.5-5.0
w
Winter
2.8
Surface to 100
251-500
2.5-5.0
w
Spring
0.9
Surface to 100
251-500
2.5-5.0
w
Summer
0.7
Surface to 100
251-500
2.5-5.0
w
Fall
0.9
a Frequencies ar? not ladditive since they are expressed as percentages of the
observations wir.h the given conditions, i.e., 2.8% of all winter time upper
air observations had conditions that may lead to plume dispersion towards
the mountains.
2-30
-------
monitors near the smelter and by the frequent occurrence of
meteorological conditions conducive to such impacts. This result
is also supported by EPA's statistical analysis showing more
violations when the smelter is operational than when it is down
(see Section 7). More fugitive emissions from the smelter are
generated when the plant is operational.
2.3 REQUIRED EMISSION REDUCTIONS
In order to meet the ambient air quality standards for TSP,
concentrations at the monitors and/or receptors must be in com-
pliance. In this case, the most restrictive concentrations would
appear to be the 24-hour values. The highest 24-hour concentra-
tion estimated by Valley under worst-case conditions is 1914
yg/m"^, which occurs at 1.5 km to the southeast of the plant at an
elevation of 7 600 feet above sea level. Based on the maximum
contribution possible from each source (i.e., main stack - 1789
pg/m^, fugitive emissions - 100 pg/m^, tailings pond - 0 ug/m"^,
and background - 25 ug/m^), the control of emissions from the
main stack seems most appropriate. Subtracting the fugitive and
background contributions from the TSP primary NAAQS (260 ug/m3)
3
results in a required reduction to 135 yg/m at the main stack.
3
Similarly, for the secondary NAAQS (150 ug/m ), the main stack is
required to reduce to a maximum impact of 25 yg/m^. The fol-
lowing proration of emissions indicates the required emission
control levels.
2-31
-------
Primary NAAQS =
1789 -135
1789
= 92 percent control
Secondary NAAQS =
1789 -25
1789
= 9S percent control
Therefore, based on data obtained by usir.g the Valley Model, con-
trol of 92 percent of the emissions from the main stack should
enable the McGill Smelter to meet the primary TSP NAAQS, as
estimated at receptors located in the eastern mountains. Because
of extremely different source dispersion and the interaction of
pollutant flow in the complex terrain near the smelter, the
control of the main stack may not be sufficient to avoid viola-
tions of the NAAQS at all locations around the plant site. This
fact is especially evident when consideration is given to the
impacts the fugitive emissions from the smelter may have on
nearby receptors (see Table 2-8). Thus, this analysis indicates
a combined control strategy for the important sources may be
I :
necessary to insure, compliance at all receptors. Since the emis-
sion estimates for the fugitives at the smelter are tenuous and
no source specific emissions are developed, including them in a
source control strategy is difficult at this point.
2.4 SUMMARY
PEDCo has verified all inputs and results as originally
modeled by EPA and Kennecott. Based on updated and/or revised
source characteristics, meteorological data, and receptor loca-
tions, similar results are obtained for ooth the 24-hour and
annual average calculations. After a review of several evalua-
tions of the Valley Model in the literature, T:he conclusion is
2-32
-------
drawn that it estimates maximum concentrations generally within a
factor of two. Under some conditions Valley may overestimate
by more than a factor of two. Only one case identified a
source/receptor distance similar to that at McGill with concen-
tration estimates four times the observed. The method of appli-
cation employed by EPA and Kennecott appears to be consistent
with the Guideline on Air Quality Models^ and the Regional Work-
shops on Air Quality Modeling,^ although documentation provided
to PEDCo is incomplete.
The following list describes the most serious inadequacies
in the modeling besides the model itself:
0 Undetailed treatment of tailings pond emissions
0 Undocumented background concentration
0 Inadequate discussion of source contributions
The first two points will be addressed in a subsequent chapter
and analysis in this report. The last point is very important.
If a control strategy for the main stack is applied and the stack
is an isolated point source, then emission reductions would cer-
tainly protect the air quality in the Steptoe Valley. The main
stack is not isolated, however, and it is surrounded by other
sources of particulate emissions that have been demonstrated
through modeling also to contribute to violations of the stan-
dards. Monitoring data and visual observations taken by Kennecott
have also demonstrated that under higher windspeed conditions
emissions from the tailings pond may exceed the standards (even
when the smelter is down). Thus, control of the tailings pond,
2-33
-------
the smelter fugitives, and the main stack emissions appear to be
required to ensure protection of the NAAQS under all meteorolog-
ical conditions at all sites in the Steptoe Valley.
2-34
-------
REFERENCES FOR SECTION 2
1. Kennecott Copper Corporation. An Analysis of Kennecott's
Particulate Control Strategy at the McGill Nevada Operations.
Submitted to U.S. Environmental Protection Agency. July 30,
1979.
2. Kennecott Copper Corporation. An Emission Inventory and As-
sessment of the Particulate Control Strategy for the McGill
Operations of the Kennecott Copper Corporation. Submitted
to U.S. Environmental Protection Agency. August 7, 1979.
3. TRW Systems Group. Air Quality Display Model. Prepared for
National Air Pollution Control Administration, DHEW, U.S.
Public Health Service. Washington, D.C. November 1969.
4. Halitsky, J., et al. Validation Studies of a Modified
Potential Flow Model for Dispersion in Complex Terrain
Submittal and Summary of Comments of Kennecott Copper Cor-
poration. Unpublished. September 21, 1979.
5. Burt, E. W. Valley Model User's Guide. EPA-450/2-77-018.
U.S. Environmental Protection Agency. Research Triangle
Park, North Carolina 27711. September 1977.
6. U.S. Environmental Protection Agency. Guideline on Air
Quality Models. EPA-450/2-78-027. Research Triangle Park,
North Carolina 27711. April 1978.
7. U.S. Environmental Protection Agency. Regional Workshops on
Air Quality Modeling: A Summary Report. Office of Air
Quality Planning and Standards. Durham, North Carolina.
September 1979.
8. Burt, E. W., and H. H. Slater. Evaluation of the Valley
Model. Presented at the AMS-APCA Joint Conference on
Applications of Air Pollution Meteorology. Salt Lake City,
Utah. November 29 to December 2, 1977.
9. Churton, B. M., et al. Modeling vs. Monitoring: A Refining
Case History in Complex Terrain. Preprint No. 23-80.
Presented at the 45th Michigan Refining Meeting. Houston,
Texas. May 14, 1980.
2-35
-------
10. Holman, H. Y., and S. R. Hayes. Survey and Assessment of
the Literature on the Performance Evaluation of Selected
Gaussian Models. U.S. Environmental Protection Agency.
Research Triangle Park, North Carolina. February 1979.
11. Luntz, R. B., G. F. Hoffnagle, and S. B. Pawha. Diffusion
Model Comparisons to Measured Data in Complex Terrain.
Third Symposium on Atmospheric Turbulence, Diffusion, and
Air Quality. American Meteorological Society. Raleigh,
North Carolina. October 1976.
12. Slowick, A. A., and N. Pica. A Field Comparison of the EPA
"Valley" Model, "Half-Height" Model, and a Suggested New
Model in Complex Terrain Under Stable Atmospheric Condi-
tions. Pennsylvania Electric Company, Johnstown, Pennsyl-
vania. August 31, 1976.
13. Turner, D. B.J and A. D. Busse. Users' Guides to the Inter-
active Versions of Three Point Source Dispersion Programs:
PTMAX, PTDIS, and PTMTP. U.S. Environmental Protection
Agency. Research Triangle Park, Nor~h Carolina. June 1973.
14. U.S. Environmental Protection Agency. Air Quality Data -
1977 Annual Statistics. EPA-450/2-73-040. Research Triangle
Park, North Carolina. September 1973.
15. Larsen, R. I.! A Mathematical Model For Relating Air Quality
Measurements to Air Quality Standards. AP-89. U.S. Environ-
mental Protection Agency. Research Triangle Park, North
Carolina. November 1971.
I!
16. National Climatic Center. Inversion Study 1960-1964. Job
No. 13105. Asheville, North Carolina. June 18, 1973.
2-36
-------
SECTION 3
ANALYSIS OF KENNECOTT'S DECEMBER 13, 1979, SUBMITTAL
On December 13, 1979, Kennecott submitted a report outlining
their position on whether the McGill Smelter contributes to
violations of the TSP NAAQS. The report, entitled "Kennecott
Minerals Corporation Notice of Violation Conference," consists of
four parts:
1. Overview of the issues
2. Summary of a monitoring research program
3. Airborne plume measurement program
4. Overview of 1972 SO2 measurement program
The primary focus of Kennecott's paper is that violations of the
\
TSP NAAQS are caused by the tailings pond and not the main stack.
Their methodology is to demonstrate that emissions from the main
stack do not contribute significantly to air quality readings
taken at receptor locations in the Steptoe Valley and in the
mountains to the east of the plant. Concentrations of SO2 and
TSP are compared at several monitor locations, based on the as-
sumption that ratios of SO2/TSP emissions from the main stack are
constant. Since the main stack is the primary source of SO^
emissions in McGill, Kennecott assumed that SO2 emissions and
downwind concentrations would be a reasonable surrogate for
3-1
-------
tracking the TSP contribution of the main stack. Thus, Kennecott
describes the SC>2 concentrations at several monitors, applies an
SC^/TSP emission ratio factor (average factor of 29.1 or 30 from
Method 5 tests), and estimates the TSP contribution of the main
stack. The difference in total TSP and estimated TSP from the
main stack is attributed to other sources in the area (fugitive
emissions from the smelter, emissions from the tailings pond,
crushing operations, etc.).
Limited special monitoring and SC^ monitoring conducted in
1972 are used to substantiate Kennecott's position. They also
present a report bv North American Weather Consultants"'" that
examines the SC^/TSP- ratio at distances downwind from the main
stack where maximum concentrations are expected to occur. The
following sections discuss various portions of Kennecott's sub-
mittal.
3.1 KENNECOTT'S NOVEMBER 197 9 RESEARCH PROGRAM
Kennecott conducted a research program aimed at determining
the effect of smelter emissions on ambient particulate concentra-
tions in the area surrounding the smelter. Concentration of TSP
can be determined by tracking the dispersion of and downwind
concentration of SO^, provided the main stack is the only source
of S02 in the McGill area and that the TSP behaves as a gas (the
particulates are less than about 20 ym in size). This method-
ology is strongly dependent upon the final assumption that the
ratio of SO2/TSP emissions in the stack gases is known, remains
3-2
-------
constant over time, and will remain consistent after plume dis-
persion. Kennecott took 39 measurements of SC^/TSP ratios using
Method 5 procedures; the average ratio of all cases is about 30.
This SO^/TSP ratio is used together with measured SC>2 data to
estimate the maximum impact of TSP emissions from the main stack.
Kennecott demonstrates that the worst-case impact of the smelter
3 3
stack i,s about 9 ug/m for valley monitors, 30 to 108 ug/m for a
3
mountainside monitor (based on 1972 SC>2 data) , and about 6 ug/m
(based on a 1979 mountainside measurement).
The basic inadequacies in this analysis stem from Kennecott's
use of a ratio of 30, the very limited data base and monitoring
program, and the limited modeling performed to establish other
source contributions to the NAAQS violations. As stated in
Kennecott's submittal, several other particulate sources, includ-
ing emissions from the tailings pond, smelter fugitive emissions,
etc., may contribute to the TSP concentrations. Though determined
by EPA to be inappropriate, Kennecott's previous analysis of
these sources should have provided an overview of source con-
tributions and interactions under various meteorological condi-
tions. Kennecott did not discuss this adequately.
The monitoring program included in the report (PEDCo did not
receive Tables 1 and 2 of this submittal) appeared to be very
limited, especially in regard to the mountainous regions. Only a
2-week monitoring program (November 12 to December 1, 197 9)
conducted at two sites (one corresponded to the maximum impact
location designated by EPA) is presented. This program is inade-
quate for a discussion of a 24-hour maximum or secondary maximum
3-3
-------
because of the slim chance that worst-case meteorological and
emission conditions would occur at the same tiir.e. Also, the 197 2
SO2 data presented in the submittal include only one data point,
situated about 1.3 km (0.8 mile) to the east of the main stack.
The measured value of SO~ at this location is €280 yg/m for a
1 ^
30-minute average or, based on Kennecott's conversions, about 904
3
to 3252 yg/m , depending on the 24-hour extrapolation factor
used. Additional monitoring may yield substantially higher
concentrations of SC^.
Kennecott's use of an SC^/TSP ratio of 30 is inconsistent
with establishment o.f a potential worst-case emission scenario.
If TSP emissions are assumed to be 2100 lb/h as a worst case, as
in Kennecott's previous short-term modeling, then a more repre-
sentative S02/TSP iratio is one near this level of TSP emissions.
Several cases in Kennecott's submittal illustrate this point,
with SC^/TSP ratios ranging from 13.1 to 16.7, or about half of
the assumed value|of 30. Use of these values may substantially
increase the TSP estimate in Kennecott's analysis, especially for
the upper limit of the mountainside analysis, e.g.:
32 52/13 J1 = 248 yg/m3
3252/16.7 = 195 yg/m3
Thus, the limited'data base presented by Kennecott indicates that
the main stack may exceed the secondary TSP NAAQS on nearby ter-
rain. In addition, the data in Kennecott's submittal show a
wide variation injthe SC^/TSP ratio and consequently, the use of
a constant ratio is probably not justified. The data are so
3-4
-------
limited, however, that no reasonable or defensible conclusion can
be made.
3.2 REVIEW OF NORTH AMERICAN WEATHER CONSULTANTS STUDY
In September 1979, North American Weather Consultants per-
formed an air sampling program of the plume emitted from the main
stack of the McGill Copper Smelter. Kennecott's primary purpose
for this study was to track the SO2/TSP plume under stable,
light-wind conditions and to determine if an SO^/TSP ratio of 30
is maintained out to distances of potential plume impaction.
Winds to the north of the stack are required to enable an air-
craft to penetrate the plume and to provide a relatively undis-
turbed (by complex terrain) plume.
According to North American Weather Consultants, the purpose
of the air sampling program was "to examine particulate disper-
sion rates along the plume centerline and compare the data with
estimates provided by centerline concentration and horizontal
3
dispersion components of Gaussian dispersion models."
The sampling rationale is as follows:
1. Under stable meteorological conditions, SO2, TSP, and
SFg were sampled in the Kennecott plume 2 km downwind
from the plant. The SFg gas was released and the
emission rate (source strength) was measured. The
dispersion rate based on the concentration-emission
ratio, Xsf6/QsFg> was applied to the measured TSP and
SO2 concentrations in order to estimate TSP and SO2
source strengths emitted from the stack.
2. The distance of 2 km was selected because it is the
approximate distance to the nearest high terrain, where
highest ground-level concentrations were expected via
modeling.
3-5
-------
3. A model was applied to the meteorological and source
strength data to calculate peak plume centerline con-
centrations at 2 km from the stack.
4. A series cf traverses was made through the plume at the
estimated height of maximum concentration. The edges
of the plume were determined by the response of a
nepheloir.eter that is sufficiently sensitive to locate
a coherent plume within 1 to 2 seconds of encountering
it if the aircraft is flying at nominal sampling
speeds. : This device is not very accurate for use in
estimating the time in the plume, which in turn is used
to estimate the appropriate total volume flow through
the particulate sensor, especially considering the
narrow plume width (100 to 200 m) at 2 km downwind.
It should be hcted that the report is ambiguous on several
points. Contradictory dates for the sampling activity are given.
The report provides no information as to the number, times,
duration of the traverses or measured data on any traverses,
plume dimensions, vertical temperature profiles, nature of wind
calculations, aircraft speed, or sample flow rates. The TSP and
SC>2 source strengths are determined in a generally ambiguous
manner. It is therefore not possible to replicate the data
presented in the titles of the report. All conclusions must be
based on the data 'presented in the tables.
The investigators strive to ascertain a, peak concentration.
The averaging time or spatial dimensions of the peak are not
specified. Why thlis approach was taken is not known, since the
shortest NAAQS for; TSP is 24 hours. The objective should have
been to obtain a validation of a dispersion coefficient for a
longer period, perhaps for an hour.
3-6
-------
Given their approach, there is a requirement to sample
through the plume centerline. Because this is very difficult to
do on each traverse, the maximum number of traverses possible
should be made. The report only estimates the approximate number
of traverses that are made and does not indicate the number
needed to locate the centerline altitude.
The authors attribute the variability of the peak concen-
trations on each traverse to the sampling technique and source
strength variations. Another equally likely cause is the in-
herent variability of the contaminant's distribution within the
plume that results from the turbulence of the atmosphere. It is
remarkable that these fluctuations are not much greater. This is
the reason that dispersion coefficients are expected to represent
some statistic of random nature of turbulence and the reason
Gaussian approaches are used to such an extent in estimating
impacts.
The reason for citing the Valley Model is unclear. This
model is not used and is not applicable to an averaging time
appropriate to a plume traverse. The mean data developed in this
study tend to support some of the input data often used in the
Valley Model.
Apparently serious difficulties arose in obtaining proper
flow rates for the TSP measurements on September 16. Therefore,
TSP data for the first four data series are suspect. Valid
data are provided only by Series 5 and 6 on September 17, which
provided a total of 2-1/2 hours of "flight time" and an unspeci-
fied period of plume sampling time. This is an inadequate sample
3-7
-------
on which to base judgments as to typical dispersion characteris-
tics of the area. Nevertheless, Ely is located in a geographical
area that experiences circumstances similar to "hose that pre-
2
vailed on September 17 (see Holzworth, EPA 650/4-74-002, 1974
and Holzworth and Fisher,"^ EPA 650/4-79-026, 1979).
The early morning NWS upper-air soundings obtained from Ely
Airport show F stability near the surface on all days (Figure
3-1). The top of the inversion on September 16 is 254 m, however,
and the smelter plume may have penetrated it.' Unless the flight
operations were begun by sunrise or very shortly thereafter, the
plume would have been changing its character very rapidly. Under
i
these circumstances, it is remarkable than the model/measured
ratio for SF^ was between 1.0 and 1.2. The dispersion coeffi-
cients must apply well to the Kennecott area, and the investi-
gators made excellent meteorological decisions.
Kennecott's argument that the SC^/TS? emission ratio "is
about 30" is not supported by the results of this flight and data
analysis study. The'data that apply are the measured mean peak
SC>2 and TSP concentrations on Data Series 5 and 6, where the
SC^/TSP ratios are -4355 = 9.3 and "^7 91 = 19.3. Thus, Kennecott
appears to overestimate the ratio of SC^/TSP when using a ratio
of 30. In addition, the data indicates that the ratio is not a
constant.
3.3 REVIEW OF 1972 SC>2 BUBBLER DATA
As part of their December 13, 197 9, submittal, Kennecott
included measurements of S02 taken around the'smelter in 1972.
3-8
-------
500
450
400
350
300
250
200
150
100
50
0
0.0253°C/m
Figure 3-1. NWS temperature versus height for Ely, Nevada,
September 16-19, 1979.
-------
Concentrations are presented for the following dates: August 24-
27, 1972, and Septerber 3-13 and 26-28, 1572. These concentra-
tons were measured at various sites near the tailings pond, north
of the plant at Gallagher Gap, northeast of the plant in the
foothills, and due east of the plant near the point that the
Valley Model estimated to have the maximum plume impact. The 30-
3
minute concentration (6280 yg/m ) presented for August 24, 197 2,
at 0.8 mile or 1.3 km east of the plant is the highest concentra-
tion in the data presented by Kennecott. No other data are
presented for this particular site and no details are given
concerning windspeecs, wind direction, or general atmospheric and
emissions conditions.'
All SC>2 samples are collected by using a RAC bubbler, Model
440-B, over a 30-minute period at a rate of 1 liter of air sam-
pled per minute. Tha laboratory method of analysis utilized the
Pararosaniline Method that was published in the 1972 Federal
Register and in the Code of Federal Regulations, Part 40, Chapter
1, 1972. As specified in the suggested methodology, the samples
were kept in insulated boxes with ice to deter further sample
reaction. No refrigeration other than the insulated boxes was
available because of the remote site location of the monitors.
During sampling, the bubblers were shielded from the sun to
maintain lower sampling temperatures and prevent sample reaction.
The barometric pressure was noted and adjusted for the site
elevation. Thus, all airflows were corrected for the proper
conditions.
3-10
-------
Based on discussions with Kennecott personnel who actually
carried out the 1972 SC^ measurement program, the results pre-
sented appear to be reasonable and within the limits of the 197 2
quality control methods.
3.4 SUMMARY
The 4-day aircraft study provided 2-1/2 hours of flight
time, during which the investigators concluded that valid and use-
ful data for all aspects of the study were collected. Actually,
these data were collected on one day, September 17, 1979. This
is an inadequate sample to judge the character of the dispersion
of the area.
No dispersion "components" are presented, as the stated
purpose of the study would imply. Based on the most reliable
data (SF,), however, the mean concentration ratios for the model
b
were 1.00 to 1.28. These are the most representative data for
the stated purpose of the study since the NAAQS for TSP is a 24-
hour average and not a peak value. These data confirm that the
centerline model worked remarkably well. Though the sample is
small, the result supports the applicability of a Gaussian model.
An unresolved problem in this experiment is the SC^/TSP emis-
sion ratio. Kennecott1s estimate of the SC^/TSP ratio exceeds
those experimentally derived in the plume by a factor of 1.5 to
3.2. The experiments also show that the SC^/TSP ratio varies
widely and is not a constant as assumed by Kennecott. Thus, the
results presented in Kennecott's portion of this document do not
consider the experimentally derived plume SC^/TSP ratio and do
3-11
-------
not reflect the potentially higher concentrations found if a
lower value of the ratio is used. Higher concentrations are
especially noted if the SC>2 concentration measured over a 30-
minute averaging period in the mountains to the east of the plant
is extrapolated to a 24-hour average and converted to a TSP
concentration.
3-12
-------
REFERENCES FOR SECTION 3
1. Schanot, A. J., et al. Aerial Measurements of Plume Dis-
persion at the McGill Smelter. NAWC-SLC-79-13. North
American Weather Consultants. Salt Lake City, Utah.
November 1979.
2. Holzworth, G. C. Meteorological Episodes of Slowest Dilu-
tion in Contiguous United States. EPA-650/4-74-002. U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina. February 197 4.
3. Holzworth, G.C., and R. W. Fisher. Climatological Summaries
of the Lower Few Kilometers of Ravinsonde Observations.
EPA-600/4-7 9-026. U.S. Environmental Protection Agency.
Research Triangle Park, North Carolina. May 1979.
3-13
-------
SECTION 4
REVIEW OF KENNECOTT'S SEPTEMBER 21, 197 9, SUBMITTAL
COMMENTING ON EPA'S llOg ACTION
Table 1-1 in Section 1 contains a chronological listing of
SIP strategies to control TSP at the McGill Copper Smelter.
Kennecott submitted two TSP control strategies to EPA on July 30
and August 7, 1979, parts of which have been reviewed in previous
sections of this report. The EPA has not yet approved control
strategies for Kennecott's smelter and/or the revised October 7,
1976, SIP TSP emission regulations. In the interim, the Governor
of Nevada issued a 110(a)(1) suspension of Article 7.2 to allow
Kennecott to continue operations. On September 13, 1979, how-
ever, EPA disallowed the suspension because Kennecott failed to
demonstrate that the SIP revision upon which ;the suspension was
issued would protect the NAAQS. Kennecott submitted a reply on
September 21, 1979, m response to EPA's "Disapproval of Tempor-
ary Emergency Suspension of an Implementation Plan," 44 Federal
Register 53305 et seq., September 13, 1979. This submittal
consists of three parts:
0 Comments prepared for EPA and submitted by Kennecott's
legal counsel, Mr. Alfred V. J. Prather.
0 Answers to EPA's objections provided by a September 11,
1979, hearing record.
0 Kennecott1s comments and technical papers submitted as
part of the September 11, 1979, hearing record.
4-1
-------
4.1 COMMENTS OF KENNECOTT COPPER CORPORATION
The first part of Kennecott's September 21, 1979, submittal
is essentially a four-page summary describing the state of
affairs. Kennecott was confused and dismayed at EPA's failure to
attend a public meeting on September 11, 1979. During this time,
Kennecott and the State of Nevada anticipated that they had not
resolved EPA's objections to the SIP revision. Despite this
fact, the SIP revisions adopted by the State at the hearing were
submitted to EPA and a new suspension order was issued. The
submittal states the basic issues between EPA and Kennecott: (1)
Do smelter emissions cause violations of the 24-hour NAAOS, and
(2) Can present emission limitations be met by reasonably avail-
able control technology? Kennecott's legal council suggests
these matters be resolved before any type of litigation proceeds
and also appeals to EPA for further meetings to aid in their
resolution.
4.2 REPLIES TO EPA'S OBJECTIONS
The Nevada Stjate Environmental Commission held a public
hearing in Reno, Nevada. Afterward, on September 11, 1979, the
Commission adopted) amendments to the TSP emission regulations.
These amendments w|ere intended to eliminate EPA's objections to
the Nevada State Implementation Plan and the Governor's August
24, 1979, suspension order. Of the five objections mentioned in
Kennecott's replies, the most critical is the first:
4-2
-------
First, the revision does not provide for attainment of the
ambient standards, as required by Section 110(a)(2)(A) [of
the Clean Air Act]. The control strategy submitted by the
State shows that the revision is inadequate to protect the
ambient standards. Contrary to Kennecott's statements,
emissions from the smelter stack contribute significantly to
violations of the ambient standards for particulate matter.
Indeed, under certain circumstances, the stack emissions
alone can cause violations of the ambient standards.
After reviewing all pertinent information in Kennecott's
submittals, and in light of the state-of-the-art of dispersion
modeling and the decisionmaking process for regulating emissions,
agreement on the main stack impact seems to be a critical point.
In terms of available modeling and guidance a screening analysis
has shown potential high concentrations, but a more refined
analysis and/or monitoring program would help fortify or disprove
the main stack impact. Kennecott has attempted to improve
modeling efforts using the Hydrodynamic Model, but it is not
recognized by EPA as valid. Only limited TSP monitoring has
been made on the Duck Creek Range to the east of the smelter.
No TSP elemental samples have been analyzed in an attempt to
identify a source.
Much can be learned about source impacts through visual
inspection of the tailings pond and the main stack. Under light
wind and stable conditions, a stack can have an impact on the
mountains to the east (see August 24, 1972, SO^ bubbler data).
At one monitor site operated by the State and three operated by
Kennecott, the main contributors generally appear to be emissions
from the tailings pond and fugitive emissions from the smelter.
Kennecott personnel noted that emissions from the tailings pond
4-3
-------
filled the valley en occasion and that the highest emissions from
the smelter fugitives occurred during its operation. The impact
of tailings pond emissions is not expected to be very great on
the mountainsides because of the small amount of reentrainment of
tailings particles that occurs at heights as high as the main
stack and the low frequency of windspeeds toward the mountains
that are sufficient to induce particle entrainment. windspeeds
greater than 10 mph suspend tailings particles, however, and
these are often noted blowing up and down the valley. Thus,
conditions in which emissions from the main stack are most
• I
likely to have a maximum impact on surrounding terrain are dis-
similar to conditions in which tailings are most likely to have
their maximum impact. Only in a slightly unstable to neutral
atmosphere and under- sufficient wind conditions , are the two major
TSP emission sources' (tailings pond and main stack) expected to
combine impacts of!potentially equal magnitude.
4.3 REVIEW OF KENNECOTT'S TECHNICAL PAPERS
Several additional comments and technical papers were sub-
mitted by Kenrecctt to the Nevada State Environmental Commission
on September 11, 1979, in support of their position. Four parts
of these comments are statements on behalf of Kennecott that seek
primarily to disprove EPA positions and conclusions. In summary,
the control techniques proposed are found by Kennecott to be
economically and technically infeasible, the emission regulations
are not needed tc protect the NAAQS, the tailings pond will be
controlled, ar.d the NAAQS will be achieved under the Nevada SIP.
4-4
-------
Dr..Frederick Templeton's statement concerning these pro-
ceedings is probably the most succinct summary of Kennecott's
position and their attempts to meet EPA requirements. The rest
of this document gives an overview of various attempts to modify
and use the Valley Model, discussions of the Hydrodynamic Model
applications, and previous control strategy submittals (including
emission inventories and modeling). Dr. Templeton states that
Kennecott has attempted to demonstrate the smelter's impact on
the area around McGill. The use of the Hydrodynamic Model, how-
ever, has not been approved by EPA, and the Valley modifications
suggested in the Kennecott report are not documented, nor have
they been approved by EPA for use in regulatory analysis. Thus,
over the past 8 to 10 years, various dispersion models have been
applied to the McGill smelter to estimate concentrations on the
terrain to the east of the plant. Unfortunately, the state-of-
the-art modeling techniques available for this analysis have not
improved significantly, nor have any new techniques been recom-
mended by EPA for general use.
4-5
-------
SECTION 5
DEVELOPMENT OF A REFINED TSP INVENTORY AND
RELATED DISPERSION MODELING ANALYSIS
5.1 INTRODUCTION
None of the data bases used as input to dispersion modeling
performed by either KMC or EPA included an adequate inventory of
the TSP emission sources surrounding the McGill Smelter. In one
of the KMC submittals, an inventory of particulate emissions for
White Pine County was presented along with a somewhat more de-
tailed estimate of emissions for various areas of the tailings
pond. No modeling was performed with this inventory. All sources
in the vicinity of the smelter should be included in the data
base to ensure a more adequate investigation.
PEDCo was directed to prepare a comprehensive inventory of
all sources of particulate emissions within the immediate vi-
cinity of the smelter. A microinventory was conducted of the
area within 8.0 km of the plant. The microinventory provides
information on fugitive emissions from process operations, the
tailings pond, and other area sources and on particulate emis-
sions from the main stack at the smelter and the stack of a small
boiler at the smelter.
The microinventory does not include emissions from the
boiler at the McGill Elementary School. Available information
5-1
-------
indicates that particulate emissions from the school boiler are
negligible and therefore have little or no impact upon air
quality. Further, the KMC and EPA reports do not discuss this
boiler.
New modeling is limited to a 24-hour and annual average
application of the Valley Model. The Valley Model was selected
for consistency with previous EPA-approved modeling and with
current EPA guidance.
Based on previous modeling and on the relationship of fugi-
tive emissions to ,windspeed, the meteorological conditions
causing worst-case, '2 4-hour, TSP concentrations were determined.
The conditions for worst-case particulate emissions from the main
stack and worst-case' fugitive emissions from process operations,
the tailings pond, and other area sources are as follows:
Main stark - F stability (very stable)
Wind speed of 2.5 m/s
Impact on mountains to the east
(1.5 km)
Process operations - D stability
Light winds (<3 m/s)
Main impact near smelter (<1 km)
Tailings pond and other - D stability
area sources High winds (6-10 m/s)
Main impact near sources (<1 km)
This updated inventory will have little impact on the contribu-
tions of the fugitive particulate sources to the impact on the
mountains to the east of the plant. Thus, the conditions leading
to the maximum mountainside concentration are still due to only
the main stack and need not be remodeled. The focus will rather
5-2
-------
be to model the conditions leading to potential worst-case
combined impacts of the fugitive sources and the main stack.
5.2 EMISSION INVENTORY
The particulate emission inventory consists of two parts.
One concerns the tailings pond, including active areas and areas
under some measure of control. The other concerns remaining
areawide, nonpoint sources (i.e., minor stationary combustion
sources, mobile sources, open-burning sources, and fugitive dust
sources), which are grouped into an areawide grid system. The
only major point sources identified in this study are the main
stack and the coal-fired boiler used by Kennecott. No other
major point sources of TSP are thought to be significant in
McGi11.
5.2.1 Grid System and Equivalent Squares
2
The grid system used in this inventory covers a 180-km area
of the Steptoe Valley between the Egan and Duck Creek Mountain
ranges. The gridded area includes both the town of McGill,
Nevada, and the Kennecott smelting and milling facilities. mhe
study area has been subdivided into 23 grids. The size of each
grid is inversely related to the concentration of human activity
in that portion of the valley; i.e., areas of high human activity
are divided into a large number of small grids. Figure 5-1
shows the grid system developed for this inventory and the major
geographical features of the study area.
The tailings pond is located in the lower center of the grid
system. Fugitive emissions from the tailings pond area are
5-3
-------
4374
4373
4372
4371
4370
4369
4368
4367
4366
4365
4364
4363
4362
4361
4360
4359
f
¦ i gur
EASTING, km
5-1. Grid system and major geographical features of the study area.
5-4
-------
handled separately from other fugitive emissions, such as roadway
dust and dust from agricultural tilling. Because the tailings
pond is a major area source in the Steptoe Valley, the inventory
is designed to allow identification of specific emission sources
within the tailings area. These sources include tailings, vege-
tated areas, dunes, slag cover, lime cover, and furrowed sur-
faces. The proper treatment of each portion of the tailings pond
as a separate, identifiable source requires the conversion of
irregular areas of specific portions into equivalent squares.
The equivalent squares are entered into the Valley Model as
separate area source grids. Figure 5-2 presents the actual
configuration of each portion of the tailings pond, and the
location and size of its corresponding equivalent square.
The Universal Transverse Mercator (UTM) coordinates of the
southwest corner of each area source grid and each portion of the
tailings pond are presented in Table 5-1. In addition to the
grid and equivalent square locations, the side length of the grid
or square and the estimated mean elevation of each surface are
provided. The mean elevations are determined from the U.S.
Geological Survey (USGS) maps of the study area. The mean
elevation is calculated as the average of three point elevations
equally spaced on a transect line drawn across the middle of each
grid (or equivalent squares). The transect line is drawn in the
direction of the slope, or grade of the land.
5-5
-------
/EQUIVALENT SQUARE
POND
acres)
ACTUAL CONFIGURATION
OF POND
EQUIVALENT
SQUARE FOR
LIME COVER
(200 acres)
ACTUAL CONFIGURATION
—OF_L.IME_COVER.
EQUIVALENT SQUARE
FOR ACTIVE AND
FURROWED PORTIONS
OF THE TAILINGS POND
(1650 acres, active
(420 acres, furrowed)
EQUIVALENT SQUARE FOR
NORTHERN SAND DUNES
50 acres)
ACTUAL CONFIGURATION OF
NORTHERN SAND DUNES
-EQUIVALENT SQUARE
FOR NOPTHERN SLAG COVER
(200 acres)
EQUIVALENT
SQUARE FOR
VEGETATED AREA
(600 acres
ACTUAL
CONFIGURATION
OF SLAG COVER
EQUIVALENT SQUARE FOR
SOUTHERN SLAG COVER
(300 acres)
ACTUAL CONFIGURATION
OF VEGETATED AREA
Figure 5-2. Equivalent squares for portions of the Kennecott tailings pond.
-------
TABLE 5-1. GRID AND EQUIVALENT SQUARE LOCATION,
SIZE, AND MEAN ELEVATION
Source
UTM coordinates of
the southwest corner
Length
of side,
km
Mean
elevation,
ft
Easting, km
Northing, km
Gri d 1
684.0
4308.0
6.0
6100
Grid 2
690.0
4371.0
3.0
6300
Grid 3
693.0
4371.0
3.0
6400
Grid 4
690.0
4368.0
3.0
6200
Grid 5
693.0
4368.0
3.0
7000
Grid 6
684.0
4365.0
3.0
6300
Grid 7
687.0
4365.0
3.0
6100
Grid 8
690.0
4365.0
3.0
6150
Grid 9
693.0
4365.0
3.0
7400
Grid 10
684.0
4363.5
3.0
6400
Grid 11
687.0
4363.5
1.5
6050
Grid 12
688. 5
4363.5
1.5
6100
Grid 13
690.0
4363.5
1.5
6200
Grid 14
691. 5
4363.5
1.5
6450
Grid 15
693.0
4362.0
3.0
7400
Grid 16
687.0
4362.0
1.5
6150
Grid 17
688.5
4362.0
1.5
6150
Grid 18
690.0
4362.0
1.5
6200
Gri d 19
691.5
4362.0
1.5
7600
Grid 20
684.0
4359.0
3.0
6200
Grid 21
687.0
4359.0
3.0
6100
Grid 22
690.0
4359.0
3.0
6600
Grid 23
693.0
4359.0
3.0
7600
Tailings (active)
687.8
4364.3
2.61
6100
Tailings (furrowed)
687.8
4362.9
1.3
6100
Sand dunes (north)
689.2
4365.7
0.78
6100
Sand dunes (south)
688.3
4362.9
0.45
6050
Slag cover (north)
690.5
4363.9
0.90
6150
Slag cover (south)
689.5
4362.0
1.10
6150
Lime cover
687. 3
4365.6
0.90
6100
Vegetation
687.8
4361.8
1.56
6050
Pond
687.6
4366.4
0.63
6100
5-7
-------
5.2.2 Calculation of Source Strengths and Emissions
Determinations of point and area source emissions require
estimates of the strength of each source and the area covered by
emissions from each source. Source strength is an estimate of
the activity of the emission source during the study time period.
The rates of emission are determined by use of standard emission
factors and emission factor equations. The resulting emission
totals for the McGill study area are presented in Table 5-2.
5.2.2.1 Minor Point: Sources-
Minor point sources are stationary comDustion sources that
emit less than IOC tons of particulates per year. They include
residential and ccxnercial home heating sources and small indus-
trial sources. These minor source categories are applied to the
McGill study area to cover all stationary combustion sources
outside of the Kennecott facility. Stationary source strength is
determined from fuel1 consumption estimates, which are based on
fuel usage by housing unit. Equations 1 through 4 present the
methods used to'determine stationary source consumption of
liquified petroleux gas (LPG), distillate oil, coal, and wood in
the study area."*"
LPG usage = 24.1(Dh)(dh)(R/5.0)(ft3) (Eq. 1)
where 24.1 = fuel heating requirement, cubic feet per
dwelling-unit-degree-day1
2
= number of dwelling units heated with fuel
= number of heating-degree-days3
2
r = average number of rooms per dwelling unit
5.0 = national average number of rooms per
dwelling unit1
5-8
-------
TABLE 5-2. PARTICULATE EMISSIONS IN THE McGILL STUDY AREA BY SOURCE CATEGORY
Source category
Particulate emissions,
tons/yr (% of total)
Residential and commercial
LPG .
0.06
(<1)
Residential and commercial
distillate oil
0.79
(<1)
Residential and commercial
coal
6.14
(<1)
Residential and commercial
wood
0.70
(
-------
Distillate oil usage = 0.18 (D^) (d^) (R/5.0) (gal) (Eq. 2)
where 0.18 = fuel heating requirement, gallons
per dwelling-unit-cegree-dayl
= number of heating-degree-days^
d^ = number of heating-degree-days^
R = average number of rooms per dwelling
unit2
5.0 = national average number of rooms per
dwelling unit-*-
Coal usage = 0.0012 (D^) (d^) (R/'5. 0) (tons) (Eq. 3)
where 0.0012 = fuel heating requirement, tons per
dwelling-unit-degree-day1
= number of dwelling units heating with
fuel ^
d^ = number of heating-degree-days
R = average number of rooms per dwelling
unit2
5.0 = national average number of rooms per
dwelling unit-
Wood usage = 0.0017 (D^) (d^) (R/5.0) (tons) (Eq. 4]
where 0.0017 = fuel heating requirement, tons per
dwelling-unit-degree-day!
D, = number of dwelling units heated with
h , . 2
f uel^
3
d^ = number of heating-degree-days
R = average number of rooms per dwelling
unit2
5.0 = national average number of rooms per
dwelling unit-
5-10
-------
The emission factors selected for use with the minor sta-
tionary source strengths (fuel consumption) were taken from the
U.S. Environmental Protection Agency's "Compilation of Air Pol-
4
lutant Emission Factors." The vast majority of minor stationary
combustion sources in the McGill study are residential or resi-
dential-sized space heaters. The emission factors given in Table
4 5
5-3 are for residential-sized space heaters. ' The total emis-
sions by residential and commercial source categories for the
McGill study area are presented in Table 5-2.
5.2.2.2 Mobile Sources-
Three major types of mobile sources are found in the McGill
study area: automotive vehicles on paved highways, automotive
vehicles on off-highway surfaces, and diesel locomotives. Al-
though some airplanes fly over the study area (the airport at
Ely, Nevada, is southwest of McGill), they account for minimal
particulate emissions.
The automotive traffic on paved highways is determined from
traffic counts taken by the Nevada State Department of Transpor-
tation.^ The total number of vehicle miles traveled (VMT) per
year on paved surfaces in the McGill study area is 13.75 million
-3
miles. Based on an emission factor of 1.08 x 10 lb/vehicle
mile traveled (a value reflecting the composition of the national
4
automotive fleet in 1979), total particulate emissions from
on-highway automotive combustion were estimated to be 7.4 3 tons/yr
for the study area (see Table 5-2).
5-11
-------
TABLE 5-3|j PARTICULATE EMISSION FACTORS FOR MINOR
STATIONARY SOURCE COMBUSTION UNITS4'5
Fuel
Particulate emission factor in
all study years
Natural and licjuid petroleum
5.0 lb/106 ft3
gasa
Distillate oil
10.0 lb/103 gal
Bituminous coa
2.0 1b/ton
Wood
17.0 "sb/ton
Particulate emissions from combustion of natural gas range from 5
to 15 lb/10^ ft0, Jdepending on the design of the combustion unit
and amount of contaminants in the fuel. Liquified petroleum gas
is considered a "e-fean" fuel because it does not produce visible
emissions. The factor of 5 lb/10^ ft3 of gas is considered a
reasonable estimaije of particulate emissions from sources firing
natural gas and L|G.
The ash content islj estimated to be 12 percent (i.e., the average
content of we sterol coal.
5-12
-------
Major automotive off-highway combustion sources found in the
McGill area include gasoline-powered off-road vehicles, gasoline-
and diesel-powered tractors, and an assortment of special-
purpose and utility equipment (e.g., chain saws and electrical
generators).
An accurate estimate of the number of off-road vehicles
using the McGill study area is impossible. The number of miles
traveled by such vehicles, however, is small compared with the
total number of miles traveled by on-highway vehicles.
The use of gasoline- and diesel-powered tractors in the
study area, although quite small, is easy to estimate from county-
wide vehicle registrations.7 The amount of agricultural land
under cultivation indicates that approximately 5.4 tractors
operate in the gridded study area. Using the ratio of gasoline-
to diesel-powered tractors in White Pine County, one can estimate
that 2 tractors use diesel fuel and 3.4 tractors use gasoline.
Roughly 3400 gal of gasoline and 2000 gal of diesel fuel are con-
sumed each year by these off-highway sources. These values are
calculated by assuming that the annual fuel consumption rate for
gasoline- and diesel-powered tractors is 1000 gal/yr.1 Based on
particulate emission rates of 8.0 lb/10^ gal of gasoline and 45.7
3 4
lb/10 gal of diesel fuel, particulate emissions from tractors
in the study area total 0.06 ton/yr.
The special-purpose equipment used in the study area is
estimated to consume 9768 gal of gasoline per year. This value
2
is based on a population of 1320 persons and fuel usage of 7.4
5-13
-------
4
gal per person per year. The emission rate for small gasoline-
3 4
powered equipment is 25.0 lb/10 gal per year.
Total particulate emissions from off-highway automotive
combustion are estimated to be 0.18 ton per year (see Table
5-2). This estir.a-ce is based upon emission rates of 0.06 ton per
year for agricultural tractors and 0.12 ton per year for small
gasoline engines.
Locomotive activity was determined by measuring the miles of
main railroad track in the study area. Track mileage in the
study area was determined from USGS maps to be 24.5 miles. Based
on this value alcnc with the statewide figure of 1504.2 miles for
g
main line track, a ratio was developed to apportion the state
" 9
figure for locomotive fuel consumption. The locomotive fuel
usage for the study area was estimated to be 9990 gal/yr. Given
3
an emission factor for diesel locomotive engines of 25 lb/10
4
gal, total particulate emissions from locomotives were calculat-
ed to be 0.12 ton per year.
5.2.2.3 Open-Burning( Sources—
The open-burning: category includes combustion of residential
and commercial wastes, structural fires, agricultural burning,
and natural burning (or wildfires). Altogether, open-burning
sources in the study area are estimated to emit 20.66 tons of
particulates per yeari.
Combustion of residential and commercial waste material
produces 0.95 ton of particulates per year. This figure is
5-14
-------
based upon a waste generation rate of 0.09 ton per capita/year,1
2
a study area population of 1320 individuals, and an emission
factor of 16.0 lb of particulates per ton of waste material con-
sumed . ^
Structural fires are expected to generate an average of 0.21
ton of particulates per year. This emission rate is based upon
an annual frequency of four fires per thousand individuals,1 an
estimated consumption rate of 5.0 tons of combustible material
per fire, and an emission factor of 16.0 lb of particulates per
4
ton of combustible material.
Agricultural burning in the study area is expected to pro-
duce 19.5 tons of particulates per year. This is based upon a
1:1:1 crop ratio of alfalfa, hay, and unspecified grasses; and a
4
combined emission rate of 27.8 lb/acre per year. Roughly 1400
acres, or one-half of the cultivated land, is expected to be
^ 10
burned.
Natural burning (or wildfires) is not considered a source of
particulate emissions. The U.S. Forest Service11 indicated that
no wildfires occurred in the study area during the study year.
5.2.2.4 Fugitive Dust Sources—
The major fugitive dust sources found in the McGill study
area are paved roadways, gravel roadways, dirt roads, agricul-
tural tilling, and windblown emissions from exposed land sur-
faces. Fugitive sources were located by the use of USGS maps and
an onsite survey of the study area.
5-15
-------
Automotive activities on paved roads produce 81.26 tons of
fugitive emissions per year. This emission rate is based upon an
activity level of 13.75 million VMT and ar. emission rate of 0.012
4
lb/vehicle mile.
Automotive activities on dirt and gravel roads generate 1543
tons of fugitive emissions per year. This emission rate is based
upon an activity level of 99,480 VMT for dirt reads and 259.8 VMT
for gravel roads. The study area contains approximately 136
miles of dirt roads; two vehicles on average were assumed to
travel these roads each day. The study area also contains
26 miles of gravel roads; an average daily traffic volume of 10
vehicles was assumed ;on these roads. Equation 5 was used to
determine emission factors for fugitive emissions from dirt and
gravel roads.^
E = (0.81 s)(S/30)(P)(f) (Eq. 5)
where. E = corrected emission factor, pounds per
vehicle mile
s = silt content of road material, percent
S,= average speed of vehicle, miles per hour
P = precipitation factor
n = average number of wheels per vehicle
The values of variables used to estimate fugitive emission fac-
tors for dirt and gravel roadways are given in Table 5-4.
5-16
-------
TABLE 5-4. VARIABLES USED TO ESTIMATE EMISSION FACTORS FOR FUGITIVE DUST
FROM DIRT AND GRAVEL ROADWAYS
Variable
Dirt road on
piedmont slope
Dirt road on
valley floor
All gravel
roads
Silt content, %
24
63
12
Average vehicle speed, mph
20
20
50
Average number of
wheels per vehicle
4
4
4
Precipitation factor3
0.8
0.8
0.8
Corrected Emission
Factor (Ib/VMT)
10.4
27.2
13.0
aEquals (365 - W)/365, where W is the number of days with O.Ol inch or more
of rainfall. In the Steptoe Valley, W is 72.
5-17
-------
Agricultural tilling generates an estimated 22.50 tons per
year of fugitive emissions. This is based upon one tilling
operation per year on 10 percent (or 313.5 acres) of the agri-
cultural land.^° An emission factor for fugitive dust from
4
agricultural ti_ling was determined by use of Equation 6.
E = [1.4s/(PE/50)2] (P) (N) (Eq. 6)
where E = corrected emission factor, pounds per acre
s = silt content of surface soil, 30 percent is
the value for the percent; Valley Basin^
PE = Thornthwaite1s precipitation-evaporation in-
dex; 27 is the value for eastern Nevada^
P = precipitation factor; 0.8 is the study area
value (see Table 5-4)
N = number of tilling and harrowing operations
per year; 1 is the study area valued
The emission factor for agricultural tilling operations in the
Steptoe Valley was calculated to be 144. C lb per acre.
Windblown fugitive dust comes from three major types of ex-
posed surfaces in the study area: natural surfaces covered by
wild vegetation, agricultural surfaces, and tailings pond sur-
faces. Natural and agriculture surfaces generate 3117 tons of
fugitive emissions per year. Although this figure may seem
large at first glance, it is based on a daily emission rate of
2 2
less than 0.5 g/m ; -he study area covers 180 km . The actual
emission factors used for determining fugitive dust from natural
and agricultural surfaces were developed from the following
13
equation:
5-18
-------
E = (k) (I) (K) (C) (L' ) (V ) (P) (Cr) (Eq. 7)
where E = emission factor, tons per acre
k = proportionality factor for particles with .,
potential for long-range transport; 0.025.
I = soil erodibility, tons per acre^
K = surface roughness factor13
13
C = climatic factor
L' = unsheltered field width factor
V1 = vegetative cover factor13
P = precipitation factor
14
Cr = crusting factor, 0.16
Table 5-5 shows the values used for the above variables.
Equation 7 was also used to estimate windblown fugitive
emissions from tailings pond surfaces. Table 5-6 presents the
values used in Equation 7 to make the estimate, and Table 5-7
summarizes information about windblown fugitive emissions from
areas within the Kennecott tailings pond. An average annual
windspeed of 11 mph was derived from the National Weather Ser-
vice data at the Ely, Nevada airport. Altogether, areas within
the tailings pond generate approximately 6318 tons per year of
fugitive particulates.
5.2.3 Major Point Sources
The only major point sources in this analysis are the main
stack and the small boiler on the smelter property. Table 5-8
presents stack parameters and emission rates for these
sources; the most recent Kennecott estimates for the McGill
Smelter are used. Emission rates are based on estimates of
5-19
-------
TABLE 5-5. VALUES USED TO ESTIMATE EMISSION FACTORS FOR WINDBLOWN FUGITIVE DUST FROM
NATURAL AND AGRICULTURAL SURFACES
Land
surface
Vegetation
Soil erod-
ibility (l),a
tons/acre
Surface
rouqhnc*. s
factor
(K)b
CIima tic
factor
¦ (C)(
linsh^l ter^d
fie1d width
factor
(L1 )<<
Vegetative
covnr factor
(V )c
Precipitation
factor
(P)
Crusting
' JCtor
(Cr)f
Emission factor (E),
tons/acre
Mountain
Pinyon-juniper
forest
?2
0. 9
0.63
n.b
0 35
0 8
0.16
0.01
Valley
Sagebrush,
winterTat.
annuals, etc.
220
1.0
0.61
1.0
0 ?i
o 8
0.16
0.11
AgrIcultura1
Alfalfa
Hay
Grasses
86
86
86
1.0
0.0
0.6
0.63
0 63
0.63
0.95
0.88
0 84
0.0
0 13
0.0
0.8
0.8
0 8
1.0
1.0
1.0
Neg.
0.03
Neq.
K>
0 a Mountain soils are considered low in fine particles because of the steep slope of the land and the past, erosion of silt into th? valley basin;^ the
soil particles are considered to be 0.84 nn in diameter. An assumed factor of 0.1 was used to estimate I from the erodibility factor for sand
(220). Valley soils, which are considered to be very hiqh in fine particles.' wnre assmned an erodibility factor of 220. Sandy ^oam soil
with an erodibility factor of 86 was selected for all afjricultur.il surfaces.'-
Minimal reduction was assumed for the roc^y (mountain slope) surfaces; no reduction was assumed for the smooth open plain of the valley floor;
and variable reductions were assumed for the agricultural crops, denendinq upon thp e*tent of land preparation.
C Equals 0.345 (W^/PE^), where W is the annual average windspeed (i.e., 11 mph)~ and PE is the precipitation-evaporation index in eastern Nevada
(i.e., 27).13
^ A value of 0.5 was assumed for mountain surfaces because of the sparse nature of pinyon-juniper forests Maximum field lengths were assumed for
other types of veqetation.'J
^ "Cover ~ by~ a pit'ijofi-juniper forest was assumed to be-limited,* and cover by sagebrush was estimated to be s inn l^i- i.u u.ivhi l»jf aqrirultural
grasses. Values for cover by aorif.ul tura\ crews were taVnn from Reference 13.
f M
A five-sixth reduction was assumed for natural crustmn nf soil surface.
-------
TABLE 5-6. VALUES USED TO ESTIMATE FACTORS FOR WINDBLOWN FUGITIVE DUST
FROM THE KENNECOTT TAILINGS POND
Tai1inqs surface
Control
measure
So 1
prodihi1ity
( 1 ) .a
ton*. a< re
Sur at r
rrnjqhnp*
fai fur (> )!'
f 1 ll'id t 1 c
' A>_ t or
(' )'
Un'.hpl tered
f i«' 1 '1 width
factor
(i -)'1
Vf"if>'at i vp
{ IIV'1'
i <)« tor
(v )-'
Prpcipitation
fac t or
(P)*
Crustinq
fac tor
(Cr)f
Control measure
reduction factor
(C.m)q
Emission
factor (E),
tons/acre
Ac 11ve tailinqs
None
,vo
1 . n
0 6 i
1 00
1.00
0 fl
2 78
Furrowed tai 1 lnqs
f urrowmg and
irriQd 11On
??u
1 0
0 61
1 00
1 00
0 8
0 8
0.94
0.52
Sand dunes (north)
None
??0
1 0
0 6.1
1.00
1 00
0 H
2.78
Sand dunes (south)
None
S?i)
1 fl
0 63
0 18
1 00
0 R
2.73
Slag cover (north)
Iron slag
19
I n
0 63
0 10
1.00
0 R
0.56
Slag cover (south)
Iron slaq
4n
l n
0 61
0 90
1 00
o n
0.57
L "ne cover
Lime slurry
Thp 'Jan covr» ornd'hil'ty indp» 1 <; har«pd upon a ?2 percent reduction in the silt content
of slaq as co^parpd with sand, p ¦ pro', <,rw| *«; ^ rrduriinn r t »o (v), whom q i s thr silt rnnfont of slaq divided by the s' 1 t content of tailings,
s I ) t CO"t pn t O t | rnn S 1 wa *> dfl^Mtno'l to ho 0 ')? ppr( nnf , a od t ho «; i M conlpnf nf -md wa ri dPtprr>«nr»d to hp 0 pprfPn t ' '
^ Values of l.o indicate nr) Significant rpdurtion nf wind nrnsmn hPr.au',p of surface rnuqhnpss, fhr vpqptatiyp COVPr factor is has**d on a
minimal amount Of reduction hpcaus»' Of I " I h ,1 I f * 1 1 prpparafwn ho'ftr-r. planting
C Cquals 0 315 (W^/Pf^), whprp w is thp annual .ivnr^ir windr,pppd [1 n . II mph)1 *nd Pf is thp prpr 1 p i t a 11 on-evapora t i on inde* in eastern Nevada
( 1 .p . 27) '3
^ Ppfprpnrp 13
P Equals ( 16S-P)/36^, whprp P is thp nun-hnr nf davs of pmr ipi t inn |n this st'jdy .lrpa P is POual to 71 days
f I 4
/\ fivp-sixt.h reduction was assu'md for natural ( nr.tmn of soil surfaro
1R
^ Equals {16S-I/16S, whprp I is tho nimh^'' of d-iy' nf imrnfinn |n thp studv arp*, I tt, appro* imatpl y ?\ days.
-------
TABLE 5-7. WINDBLOWN FUGITIVE EMISSIONS FROM THE
KENNECOTT TAILINGS POND
Tailings
surface
Surface area,
acres
Emi ssion
factor,
tons/acre per yr
Emissions,
tons/yr
Active tailings
1680
2.78
4670
Furrowed tailings
420
0.52
219
Sand dunes (north)
150
2.78
417
Sand dunes (south)
50
2.73
136
Slag cover (north)
200
0.56
114
Slag cover (south)
300
0.57
168
Lime cover
200
0.48
96
Vegetative cover
600
0.83
498
Pond
100
0.00
0
Total
3700
6318
5-22
-------
TABLE 5-8. STACK PARAMETERS AND PARTICULATE EMISSION RATES
FOR THE MAIN STACK AND SMALL BOILER
Main stack
Stack height
229 m
Stack diameter
4.7 m
Gas exit velocity
21.2 m/s
Gas temperature
422K
Emission ratea
259.20 g/s
Small boiler
Stack height
32 m
Stack diameter
2.1 m
Gas exit velocity
2.1 m/s
Gas temperature
300K
Emission rate3
15.13 g/s at 25;;
capaci ty
aEmission rates are maximum hourly actual emissions assumed to occur at least
6 hours per day.
5-23
-------
worst-case or maximum short-term release to maximize the 24-hour
ambient concentrations.
The locations of the stacks are given in UTM coordinates in
Section 1. The distance between them is roughtly 210 meters.
Fugitive emissions are released from the smelter at a
height of 45 meters. The area width for smelter fugitives is 300
meters, and the emission rate is 90.71 g/s. No refinement of
the smelter fugitives was attempted in this analysis because of
the uncertainty in temporal and spatial characterization. The
emissions were characterized as in previous Kennecott analyses.
5.2.4 Appropriateness of Emission Estimates
The emission estimates were based on the best data available
at the time of the inventory. Particular emphasis was placed on
trying to define as much of the tailings pond area as was pos-
sible. Grab samples of the tailings pond surface and sand dunes
were made to ensure an adequate estimate of aggregate content for
these sources.15 The mean silt content of the Valley soils was
estimated from regional data available from the University of
1 °
Nevada at Reno. ^ Surface erosion, windspeed, precipitation, and
other factors were considered in estimating emissions (see Tables
5-4, 5-5, and 5-6). When emission factors had to be tailored for
specific areas (e.g., portions of the tailings pond, agricultural
land, and natural!surfaces), attempts were made to obtain specif-
ic data; when specific data were unavailable, assumptions were
made on the basis of onsite survey results.
5-24
-------
Main stack particulate emissions are based on stack
sampling under typical load conditions and represent maximum
measured hourly releases. Smelter fugitives are considered to
be 35 percent of the main stack release. The estimated rate of
emissions from the small smelter boiler is based on coal usage
at 25 percent load condition; according to Kennecott personnel,
this represents the maximum load the boiler experiences in any
24-hour period.
5.3 MODELING METHODOLOGY AND RESULTS
5.3.1 Overview
Two Valley Model applications are addressed in this anal-
ysis: an annual average concentration estimate and a 24-hour
estimate. Source contributions for each application are pre-
sented .
The 24-hour averaging analysis is performed in the same way
as the analysis in Section 2. The annual average concentration
methodology, however, differs to some degree from previous Valle
modeling. In this study, emission estimates from each area or
fugitive source are treated as a function of windspeed. Using
an emission rate based on the annual average windspeed would
have overestimated emissions for low windspeeds and underesti-
mated them for high windspeeds. Instead, area emissions were
adjusted for the central windspeed of each STAR windspeed class
(i.e., 0.67, 2.45, 4.47, and 6.93 m/s and greater). The class
of windspeeds greater than 6.93 m/s is thought to be representa-
tive of higher windspeeds.
5-25
-------
Only that portion of each total fugitive source that is
dependent upon the wind is affected. Some sources of particulate
emissions (e.g., vehicles on unpaved roads or agricultural til-
ling) are only partially affected by the windspeed changes.
Other sources (especially the tailings pond) are dependent solely
upon windblown emissions.
'For each climatological weighting factor (STAR) applied to
the basic Valley dispersion calculations, an associated emission
factor is applied. [This procedure results in a more refined
treatment of windblojwn sources and accounts for the variable
background concentra'tions. Because annual particulate emissions
from the main stack jand small boiler and emissions from the
fugitive smelter werie not estimated, the rraxlmum 24-hour emis-
sions were used in the annual analysis. because the plant does
not operate at maxirium load every day for a whole year, concen-
tration estimates fc>r the annual averages are expected to be very
conservative.
5.3.2 Annual Averace Concentration Estimates
I
Current estimates of annual average concentrations are
similar to previous estimates. Fugitive emissions from the
smelter are the main' contributor to most estimated violations of
the NAAQS for TSP; concentration estimates are extremely conser-
vative because maximum emissions are assumed for the major emit-
ters. The main stack does not contribute .significantly to the
receptors near the smelter (within 0.9 km of the stack) even
under these very high emission scenarios, but may contribute to
5-26
-------
the annual concentrations estimated at maximum terrain impact
locations (i.e., to the southeast, east, and northeast of the
smelter on the mountains). Table 5-9 presents the annual average
TSP concentrations at each receptor. Estimates include emissions
from all sources. Because of the prevailing north-south wind
flow and terrain impact east of the plant, receptors in these
areas generally have the highest concentrations.
Under the annual TSP NAAQS of 75 gg/m^ (geometric mean), 36
excursions may be expected each year. As with previous EPA
modeling, no monitors are located exactly where the Valley Model
predicts annual average violations to occur. No measured TSP
violations for annual average have been found, and no violations
of annual standards are expected to occur because overly conserva-
tive major source emissions are used. The analysis is useful
from the standpoint of providing a source contribution table for
critical receptors and indicating potential tailings pond and
other fugitive particulate emissions.
Table 5-10 illustrates the contributions of various sources
to TSP levels at the five receptors with highest annual average
concentrations. Area Sources 1 through 23 make fairly consistent
3
contributions of 10 to 20 pg/m . These sources probably represent
background TSP because they generally emit some TSP under all
meteorological conditions on an annual basis. Contributions from
the main stack are negligible, even with artificially high esti-
mates used in this analysis. The small boiler, however, con-
tributes 11 to 16 percent of total estimated concentration at
each receptor. The tailings pond does not contribute more than
5-27
-------
TABLE 5-9. ANNUAL AVERAGE TSP CONCENTRATIONS9
(yg/m3)
Di recti on
Rinq
b
1
2
3
4
5
6
7
N
161
118
95
89
85
81
79
NNE
183
135
167
115
81
82
73
NE
396
141
79
57
84
58
50
ENE
206
80
95
54
51
26
23
E
178
112
79
44
25
20
17
ESE
175
57
66
51
25
22
18
SE
218
118
88
69
45
28
22
SSE
231
89
83
51
41
40
30
S
258
126
77
52
41
34
36
ssw
119
69
63
44
37
32
28
sw
81 ;
63
55
45
39'
38
33
wsw
83
61
55
53
58
40
28
w
77
58
75
77
54,
28
23
WNW
71
57
96
105
87
52
22
NW
69
68
92
118
101
77
66
NNW
137
82
79
94
92
87
78
Values are high because maximum 24-hour emissions from the main stack
and small boi'er ard maximum 24-hour fugitive emissions are assumed
to occur throughout a whole year.
^Because rings are rot round, only a ring number "s given. Each succes-
sive ring is approximately 0.8 km further from the center of the coordinate
system.
5-28
-------
TABLE 5-10. SOURCE CONTRIBUTIONS TO TSP LEVELS AT THE FIVE RECEPTORS
WITH HIGHEST ANNUAL AVERAGE TSP CONCENTRATIONS
Receptor rank
1
2
3
4
5
Direction to receptor
NE
S
SSE
SE
ENE
Distance to receptor, km
0.
67
0.
78
0.
69
0.
67
0.81
Total concentratation,
VJ g / m ^
396
258
231
218
206
Concentration contribu-
tion. (percent of total)
yg/nH
Main stack
0.0
(0)
0.1
(
-------
7 percent of the total concentration at any of the five receptors.
Most particulates at the receptors are smelter fugitives, which
contribute significantly to particulate concentrations within 2
km of the smelter. Receptors beyond 2 km are affected mainly by
particulates from the main stack, the tailings pond, and other
area sources. Because no annual average violations have been
measured at the McGill School or Townsite monitors, both of which
are in the vicinity of the maximum estimated concentrations, the
maximum estimates cf smelter fugitives are assumed to be overly
conservative. Further, this analysis indicates minimal impact
from the main stack and the tailings pond.
I
5.3.3 Short-Term 24-Hour Concentrations
All of the 24-hour estimated TSP concentrations given in
Section 2 reflect only the impact of the main stack, the smelter
fugitives, and the overall tailings pond emissions. As with the
analysis of annual avjerage estimates, a new Valley Model analysis
was performed with the improved inventory of particulate emissions.
Table 5-11 presents the maximum expected 24-hour concentra-
tions in Valley Ring .;1. The distance from the main stack to the
first ring is 0.5 to 0.8 km. Near neutral conditions (C stabil-
ity) are assumed with windspeeds of 6.67 m/s (15 mph) for at
least 6 hours in the receptor directions indicated. Compared
with the annual averages in Tables 5-9 and 5-10, these 24-hour
I
concentrations appear,very low. These tables, however, should
not be compared and should not be construed to represent worsts-
case ambient air quality. The annual averages in Tables 5-9 and
5-30
-------
TABLE 5-11. 24-HOUR TSP CONCENTRATIONS IN VALLEY RING la
Receptor
direction
Total
concentration,
yg/rn^
N
97
NNE
104
NE
106
ENE
101
E
109
ESE
112
SE
111
SSE
112
S
108
SSW
154
SW
90
WSW
81
w
83
WNW
81
NW
75
NNW
95
aThe distance from the main stack to the first ring is about 0.5 to 0.8 km;
C stability and windspeeds of 6.67 m/s (15 mph) are assumed.
5-31
-------
5-10 were calculated using maximum short-term emissions and
consequently were overly conservative. On the other hand, Table
5-11 presents concentration estimates that appear low; maximum
particulate emissions from the main stack and small boiler and
fugitive emissions from the smelter are reasonable because these
are maximum short-term emission estimates. Also, because the
tailings pond emissions are a function of windspeed, at the
assumed windspeed of' 6.67 m/sec emissions were fairly high.
These winds occur reasonably often (^5% cf the time) near McGill.
Since concentrations, are inversely proportional to windspeed in
the Valley Model, estimated concentrations due to the main stack,
the boiler, and the smelter fugitives are reduced at high wind-
speeds. Concentration estimates in the 24-hour analysis reflect
an attempt to maximize tailings pond contributions and the com-
bined impacts of the,' tailings pond and main stack in the Valley.
The maximum impact o'f the main stack under these conditions is
!
5.0 km downwind in fiat terrain (i.e., near the North Flat site).
At lower windspeeds and more stable conditions higher impacts
from the main stack and smelter fugitives may be estimated, as
seen in Section 2; but tailings pond contributions are minimal
under these conditions. Thus, the analysis used to derive Table
5-11 relies on meteorological and emission assumptions that
maximize overall tailings pond and area source emissions.
The Valley Model results indicate that the maximum 24-hour
impact of the main stack occurs 5.0 km downwind and equals
i 3
approximately 8.0 yg'/m of TSP in all directions. The Valley
5-32
-------
Model does not consider the effects of complex terrain for any of
the unstable cases. As a result, estimated concentrations are
nearly the same in each direction. As with previous modeling,
all the highest 24-hour TSP concentrations occur within 0.5 to
0.8 km of the smelter and are primarily caused by smelter fugi-
tives. One receptor to the south-southwest of the smelter is
estimated to exceed slightly the secondary national ambient TSP
3
standard (150 pg/m ). This receptor is situated within 0.3 km of
the small smelter boiler, and smelter fugitives may account for
the high concentration there. Even at high windspeeds, smelter
fugitives (which in this study are not dependent on windspeed)
contribute to the maximum estimated concentrations.
The maximum impact of tailings is immediately adjacent to or
downwind of the tailings pond. This analysis attributes no
excursions of TSP standards to the tailings pond. Maximum con-
3
tributions range from 20 to 40 vg/m to the north of the tailings
pond .
No other 24-hour analyses were conducted with the updated
inventory. Conditions leading to maximum main stack impacts and
smelter fugitive impacts (i.e., A, E, and F stabilities with
light winds) would produce TSP concentrations similar to those
generated in Section 2, because tailings pond emissions are very
low under these conditions. Although this updated inventory does
not eliminate the possibility of 24-hour violations at varying
atmospheric conditions, it shows that in general tailings pond
emissions will not cause violations of NAAQS except possibly at
extreme windspeeds (i.e., windspeeds much greater than 15 m/s).
5-33
-------
The small boiler, which was not considered in the previous
EPA and Kennecott analysis, contributes significantly to TSP
concentrations at nearby receptors under certain conditions.
Screening analysis indicates that the maximum impact of this
boiler stack occurs 0.5 to 0.8 km downwind at neutral stability
and light windspeed. Thus, a complete analysis of all stabili-
ties and wind conditions will probably show 24-hour concentra-
tions similar to these derived in the above analysis. The annual
average estimate will be smaller when emissions are adjusted for
actual operating loads and hours.
The contributicn of smelter fugitives to TSP levels at
receptors near the smelter will increase at lower windspeeds
because the fugitives do not depend on windblown emission fac-
tors. No better emission factors for the fugitives are currently
available. Such factors are extremely difficult: to estimate
because of the changing character and temporal and spatial vari-
t
ability of fugitives. Consequently, 24-hour modeling suggests
that smelter fugitives nearly always contribute high concentra-
tions of TSP to nearby receptors. The actual amount of smelter
fugitives released ever a year, however, is smaller than 24-hour
modeling indicates.
5.3.4 Height of the Main Stack
Up to this point' the McGill Smelter has received full stack
height credit for the purposes of dispersion modeling. According
to current good engineering practice (GEP) policies, however,
this smelter should only receive credit for GEP determined stack
5-34
-------
height or the taller of the two grandfathered stacks. Dispersion
analysis of the main stack with only GEP stack height (i.e., 104
meters, the height of the taller grandfathered stack) indicates
that maximum impact occurs to the east-southeast of the stack at
0.66 km downwind on the nearby mountainside. Consistent parari-
l
eters used in previous modeling are used to estimate a maximum
TSP 24-hour concentration with the Valley Model. The maximum 24-
hour concentration estimated is 2959 pg/m^, caused solely by the
main stack.
5.4 SUMMARY
A more detailed area source and fugitive emission inventory
has been assembled. Also, a small boiler on the smelter property
has been added to the original EPA and Kennecott Valley Model
analysis. For the most part, the area sources (other than the
tailings pond) account for the background concentrations that
were initially assumed. Thus modeling verifies the EPA and
Kennecott background values. The breakdown of the tailings into
subsources indicates that the active tailings emit more particu-
lates than other subsources. Particulate emissions from the main
stack and fugitive emissions from the smelter contributed to
concentration estimates in the same way as in previous modeling.
The main stack affects nearby terrain and has little impact on
close-in receptors, and smelter fugitives affect close-in recep-
tors significantly. The effects of the small boiler stack on
close-in receptors may be significant. Under grandfathered
5-35
-------
stack height cons-.ramts, particulate emissions from the main
stack are estimated to increase TSP concentrations in the nearby
mountain terrain by €5 percent.
5-36
-------
REFERENCES FOR SECTION 5
1. U.S. Environmental Protection Agency. Guide for Compiling
a Comprehensive Emission Inventory. 2nd ed. APTD-1135,
1974.
2. U.S. Department of Commerce, Social and Economic Statistics
Administration, Bureau of the Census. Detailed Housing
Characteristics, Nevada. Washington, D.C. 1970.
3. National Oceanic and Atmosphere Administration. Local
Climatological Data: Annual Summary With Comparative Data.
National Climatic Center, Asheville, North Carolina,
December 1978-November 1979.
4. U.S. Environmental Protection Agency. Compilation of Air
Pollution Emission Factors. AP-42, 1979. Supplements 1-9.
5. Combustion Engineering, Inc. Handbook. Windsor, Connecticut,
1970. p. 32.
6. Planning Division, Department of Transportation. 1979
Annual Traffic Report - Nevada Highways. Carson City,
Nevada, 1979.
7. Department of Conservation and Natural Resources. White
Pine County Emissions Inventory. Carson City, Nevada,
1978.
8. Planning Division, Department of Transportation. Nevada
State Rail Plan. Carson City, Nevada, 1978.
9. Department of Energy, Energy Information Administration.
Energy Data Reports: Sales of Fuel Oil and Kerosene,
1978. Washington, D.C., 1979.
10. Personal communications between L. Ungers, PEDCo Environ-
mental, Inc., and White Pine County Agricultural Extension
Service, Ely, Nevada. July 9, 1980.
11. Personal communication between L. Ungers, PEDCo Environment-
al, Inc., and S. Swanson, Elko, Nevada. July 9, 1980.
5-37
-------
REFERENCES (continued)
12. Personal communication between L. Ungers, PEDCo Environmental/
Inc., and F. Peterson, University of Nevada, Reno, Nevada.
July 25, 1980.
13. U.S. Environmental Protection Agency. Development of
Emission Factors for Fugitive Dust Sources. EPA-450/3-74-
037, June 1974.
14. PEDCo Environmental, Inc. Nevada Particulate Control Study
for Air Quality Maintenance Areas. Prepared for the U.S.
Environmental Protection Agency. Cincinnati, Ohio, March
1977.
15. Ungers, L. J. Tailings Sample and Particle Size Analysis.
PEDCo Environmental, Inc., Cincinnati, Ohio, August 1980.
16. Bohn, R., e- al. Fugitive Emissions From Integrated Iron
and Steel Plants. EPA-600/2-78-050, March 1978.
17. Chepil, w. S. Soil Conditions That Influence Wind Erosion.
U.S. Department of Agriculture, Washington, D.C., 1958.
Bulletin 1185.
18. Personal communications between L. Ungers, PEDCo Environ-
mental, Inc., and William G. Miles, Kennecott Minerals
Company, McGiil, Nevada. August 16, 1930.
5-38
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SECTION 6
REVIEW OF THE HYDRODYNAMIC MODEL
The objective of this section is to review the Hydrodynamic
Model of INTERA, Inc., for the appropriateness of its application
to the McGill Smelter. Appropriateness will be defined in terms
of model applicability, evaluations performed using field data,
limitations, and model use (and subsequent interpretation of re-
sults). Other names that the model has been identified by include
INTERA Model, INTERCOMP Model, and most recently the Modified
Potential Flow - Turbulent Diffusion (MPF-TD) Model. Throughout
the remainder of this review, the model will be called MPF-TD.
This review is limited to summarizing the limitations,
advantages, reasonableness, and evaluations found in the pub-
lished reports of EPA, Kennecott, and other organizations. No
specific review is presented that investigates the basis for
equations chosen, their boundary conditions, solutions, or the
selection of empirical factors. This type of review has been
summarized to some extent by Koch."'"
The following sections present a brief qualitative overview
of MPF-TD, a summary of previous model evaluations, limitations
and caveats, a review of the applications to McGill, and recom-
mendations and conclusions.
6-1
-------
6.1 MODEL OVERVIEW
The MPF-TD Model is a numerical solution of the three-
dimensional material balances for the entire air stream and the
pollutant flowing within that airstream. The model developed by
2
INTERA Environmental Consultants is a combination of modified
potential flow and turbulent diffusion. Classical potential flow
theory as applied to fluid motion is a simplification that assumes
a flow is inviscid, r.onturbulent, irrotaticnal, incompressible,
and homogeneous and requires only the solution cf the mass
continuity equation. To account for flow over terrain and for
vertical suppression of the mean flow in a stable atmosphere, the
velocity potential is modified to include a height-dependent,
empirical flow coefficient. This empirical modification causes
calculated windspeed to vary with height. The result is a
terrain-induced wind field that is used in the solution of the
diffusion equaticn,
The material balance for a pollutant advecting and diffusing
in the flow field is calculated by turbulent diffusion equations
that approximate turbulent fluctuations by a Fickian-type eddy
diffusion model. The eddy diffusivity used in the model is
height-dependent and consistent with both turbulent fluctuation
3
measurements and theory.
In all, six empirical coefficients are required to complete
a solution of MPF-TD and to calculate concentrations. These
factors define (1) the boundary layer thickness.. (2) the power
law variation of wind velocity with height as functions of
6-2
-------
stability, (3) the stability-dependent degree of suppression on
vertical flow, and (4) the degree of diffusivity. The coeffi-
cients are estimated from available field and laboratory experi-
„ 4
ments.
Generally, the MPF-TD Model is applicable in flat terrain
monitoring and yields results similar to those of the standard
Gaussian models. More specifically, the model is applicable to
rough terrain modeling and has been extremely useful in assessinc
theoretical pollutant transport over mountainous terrain. The
model is limited in its present form, however, in that it
prevents the formation of recirculating flow on the windward or
lee side of a terrain feature or obstacle. Also, because of the
elimination of the energy balance equation, the effects of mate-
rial convective flows cannot be estimated (e.g., mountain drainage
winds and lake and sea breezes) . ^
The criticality of the two limitations are noted by Koch, et
al.,"^ who found that complex terrain not only contributes to
alterations in airflow, but also to increased amounts of turbulent
diffusion compared with flat terrain. This increased turbulence
is attributed primarily to drainage flow and lee waves, two
factors noted above that MPF-TD does not consider very well.
Drainage flow as a major turbulence mechanism is very important,
especially near the surface on a mountain slope in a very stable
atmosphere. These two critical limitations of MPF-TD led to the
disapproval by EPA for its use at the McGill Smelter.
6-3
-------
6.2 MODEL EVALUATIONS
Review of MPF-TD has been rather limited since it has, until
recently, remained a proprietary model of INTERA, Inc. Review
has generally been coincidental with review of other complex
terrain models, and in this context MPF-TD compares very well in
accuracy with current Gaussian techniques. Probably of con-
siderable importance is that MPF-TD calculates a good approxi-
mation of the velocity fields on the upwind side of obstacles.
This description of the windflow in complex terrain is thought to
provide a much closer simulation of physical reality than typical
Gaussian models, even though recirculating and convective flow
treatment is neglected.
Comments in literature and recent reports are both supportive
and critical of MPF-TD. Battelle Laboratories reported to the
Electric Power Research Institute^ that the MPF-TD Model produced
ground-level concentration estimates reasonably close to field
data collected near the Navajo Generating Station in Northern
6 1
Arizona. In a report to the EPA, Geomet Incorporated commented
that the MPF-TD Model appeared to make estimates to within about
a factor of two or three of measured concentrations. The model
systematically overestimates concentrations with respect to plume
centerline in the first 4 to 5 km near the plant in complex ter-
rain. Geomet concluded from a survey of the literature and recent
field studies that neither the Valley Model or the MPF-TD Model
adequately take into account the initial dilution resulting from
emission-related parameters (buoyancy and turbulence generated
6-4
-------
by stack exit velocity and temperature). A copper smelter may
not generate the same volume or temperature of gas as a power
plant, however, and so the results here should be kept in the
context of the smelter stack. A major feature of the Geomet
report is the similarity of estimates between Valley and MPF-TD.
INTERA, Inc., was contracted by EPA to review their own MPF-
TD Model as well as other complex terrain models in the context
of several sets of monitor results from field studies in complex
terrain.^ INTERA and EPA did not agree on the interpretation of
MPF-TD results. Basically, INTERA maintains that MPF-TD yields
good estimates in complex terrain even though recirculating and
convective flows are not treated. The EPA, on the other hand,
disagrees with the overall interpretation of results and the
validity of some inputs. The disagreement stems from the defi-
nition differences of "reliable estimate." The EPA contends that
a reliable estimate must represent the near upper envelope of
observed concentrations (i.e., the upper few percentile).
INTERA interprets a reliable estimate as one that best fits an
average of observed data. Thus, conclusions of this report^ are
that MPF-TD performs well for the criteria established by INTERA,
but is not necessarily accepted by EPA.
Finally, in an unpublished paper presented by INTERA, Inc.,
4
on behalf of Kennecott, MPF-TD is found to estimate concentra-
tions to within about a factor of two. INTERA further recom-
mended additional physical modeling or field studies to determine
more realistic values for each of the MPF-TD empirical parameters.
6-5
-------
6.3 APPLICATIONS TO McGILL
Previous applications of the MPF-TD Model ~o McGill include
a 1972 application to SO2 emissions from the then proposed 229-m
main stack and the 104-m acid plant stack. The results of this
modeling indicated that SO2 concentrations greater than 328
3 7
yg/m occur with a frequency of 7.8 percent or 28 days a year.
3
The maximum concentration of 2077 yg/m occurred about 1.5 km to
the southeast of the plant at a receptor elevation near the
7800-ft level. Nc violations attributable to the stacks on an
annual average were found.
In an August 7.. 1979, presentation to. EPA, the MPF-TD S02
results from 197 2 were prorated for TSP by dividing by the SO^
emissions and multiplying by the TSP emissions. The maximum
estimated annual concentration and the maximum 24-hour concentra-
tions were 2.7 anc 124 yg/m"^, respectively. Although documenta-
tion for the MPF-TD Model is adequate to evaluate its applicabil-
ity and reasonableness for modeling the Kennecott McGill Copper
Smelter, documentation for the McGill application itself is
rather sparse. Little indication is given in the Kennecott
comments, responses, technical papers, or presentations of the
source parameters, receptor grid, or meteorological data used.
Input data probably included data similar to that in other model
applications at McGill (Valley and AQDM).
6.4 SUMMARY AND CONCLUSIONS
The MPF-TD Model is a potential flow model modified to con-
sider the effects of complex terrain and ~o include pollutant
6-6
-------
dispersion. Two theoretical limitations of MPF-TD are that it
does not consider recirculating flows (i.e., in the lee of com-
plex terrain), and it does not allow the formation of convective
flows (e.g., mountain drainage winds). These two limitations as
well as the fact that MPF-TD does not estimate the worst case
concentrations on terrain form the major basis for EPA's objec-
tion to using MPF-TD. The model has been compared with moni-
tored pollutant concentrations and has been shown to give agree-
ment to within a factor of +2. Documentation, however, for
actual past applications is rather sketchy and cannot be ade-
quately scrutinized. More recent applications and comparisons
with other modeling techniques and monitor values at McGill are
necessary to yield a clearer picture of the appropriateness of
the MPF-TD Model for application to the smelter. Also the level
of application deemed appropriate must be considered along with
the treatment of physical parameters and resultant concentra-
tions. Though the simulation of real wind flows, etc., is some-
what better in the MPF-TD Model than a more simplified technique,
the limitations noted above should be heeded in interpreting
results. Thus, the use of the MPF-TD Model for McGill may be
appropriate with better documentation to meet EPA objections,
but the results at this time are unacceptable to EPA.
6-7
-------
REFERENCES FOR SECTION 6
1. Koch, R. C., et al. Power Plant Stack Plumes in Complex
Terrain. EPA-6.00/7-7 7-020, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina. 1977.
2. Hoffnagle, G. F., V. A. Mirabella, and T. C. Spangler.
Model Simulation of a Tracer Study in Rough Terrain. First
Conference on Regional and Mesoscale Modeling, Analysis, and
Prediction. Las Vegas, Nevada, May 5-9, 1975.
3. INTERCOMP Resources Development and Engineering, Inc.
Evaluation of Selected Air Pollution Dispersion Models
Applicable ~o Complex Terrain. EPA-450/3-75-059, U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina. 1975.
4. Halitsky, J., et al. Validation Studies of a Modified
Potential Flow Model for Dispersion in Complex Terrain
Submittal and Summary of Comments of Kennecott Copper Cor-
poration. Unpublished. September 21, 1979.
5. Drake, R. L., D. J. McNaughton, and C. Huarg. Mathematic
Models for Atmospheric Pollutants, Appendix D: Available
Air Quality Models. EA-1131 Appendix D, Electric Power
Research Institute, Palo Alto, California. 1979.
I ' '
6. Lantz, R. B., G. F. Hoffnagle, and V. A. Mirabella. Com-
parison of Several Models with Ambient Sulfur Dioxide
Measurements Near the Navajo Generating Station. Presented
at 69th Annual Meeting of the Air Pollution Control Asso-
ciation , "Portland , Oregon. June 27-July 1, 1976. Paper No.
76-34.2.
7. Templeton, F. E., et al. Sulfur Dioxide Concentrations
Resulting From Air Quality Control Programs at Kennecott's
Smelters. Unpublished. Kennecott Copper Corporation.
October 13, 1972.
6-8
-------
SECTION 7
STATISTICAL ANALYSIS OF AIR MONITORING DATA
Since 1972, measurements of the 24-hour concentrations of
TSP have been made at various times at five monitoring sites
located near the McGill Smelter (see Figure 1-1). Two of these
sites, the State-operated McGill School site and the Kennecott
Townsite, are located in McGill less than 1.5 km from the smelter
plant. Two other sites operated by Kennecott, North Flat and
Gallagher Gap, are located about 5.0 and 6.0 km, respectively, to
the north of the plant. Kennecott's other site, the South Flat
site, is located 4 km south-southwest of the smelter. Measure-
ments of general windflows in the Steptoe Valley, which were
derived from meteorological data gathered at the Ely Airport and
North Flat site, indicate that prevailing winds follow the basic
north-northeast to south-southwest alignment of the valley.
Thus, the monitors are located where they can take full advantage
of the frequent winds from the direction of the various sources
of particulates.
The EPA analyzed TSP air quality monitoring data collected
at the McGill School site to determine if the main smelter stack
at the McGill Smelter is contributing significantly to violations
of the 24-hour TSP NAAQS. PEDCo has presented this independent
7-1
-------
appraisal of air quality data gathered at the McGill School and
other sites to substantiate this determination.
7.1 CUMULATIVE FREQUENCY DISTRIBUTIONS
From August 1975 to May 1979, a total of 158 24-hour TSP
measurements were collected at the McGill School site. Of this
total, 118 measurements were made on days when the smelter was in
operation, and 37 were made on days when the smelter was not in
operation. The EFA analysts constructed cumulative frequency
distributions of the TSP data when the smelter was operating and
when it was not operating (see Figure 7-1}. It is evident from
the cumulative frequency distributions that TSP concentrations
were higher when the smelter was in operation than when it was
not in operation. When the smelter was operating, both the
primary and secondary TSP standards were exceeded; when the
smelter was not operating, only the secondary TSP standard was
exceeded.
PEDCo assembled a slightly larger collection of TSP measure-
ments from the McGill School site (263 samples were collected
from January 1973 to December 1979) and constructed a similar
analysis of the samples. As can be seen in Figure 7-2, very
little difference arcse from the expanded data set. Both sets of
data (Figures 7-1 and 7-2) exhibit higher measured TSP concentra-
tions when the smelter is operating than when it is not operat-
ing. This fact alone, however, is not sufficient evidence to
7-2
-------
V SMELTER
OPERATING
(118 SAMPLES)
O SMELTER NOT
OPERATING
(37 SAMPLES)
EXCEEDS SECONDARY NAAQS 28 DAYS/YEAR _
1/365
EXCEEDS SECONO&RY
NAAQS 6 DAYS/YEAR
EXCEEDS PRIMARY
NAAQS 4 DAYS/YEAR
PRIMARY NAAQS
NOT EXCEEDED
1
25 50 75 100 125 150 175 200
TSP CONCENTRATION, ug/m
225
3
JL
250 275 300 325
Figure 7-1. TSP cumulative frequency distributions for the McGill
School Monitor: 8/76 to 5/79
(smelter operating vs smelter not operating).
7-3
-------
0.30
0. zo
0.10
0.09
0.08
0.07
0.06
0.05
0.04 -
0.03
0.02
0.01
0.009
0.008
0.007
0.006
0.005
0.004
0.003
0.002
O.OOl
0
—I 1 1 1 1 1
V SMELTER OPERATING (184 SAMPLES)
O SMELTER NOT OPERATING (79 SAMPLES);
EXCEEDS SECONDARY NAAClS 41 DAYS/YEAR
EXCEEDS SECONDARY
NAAQS 12 DAYS/YEAR
EXCEEDS PRIMARY
NAAQS 10 DAYS/YEAR.
PRIMARY NAAQS
NOT EXCEEDED
25 50
75 100
I
I
I
125 150 175 ZOO
TSP CONCENTRATION, v.g/m
225
3
250 275 300 325 350
Figure 7-2. TSP cumulative frequency distribution's for the McGill School
Monitor: 1975 to 1979 ,
(smelter operating vs smelter not operating).
7-4
-------
support the conclusion that the main stack at the smelter is the
major contributor to these violations. Previous modeling and
state-of-the-art dispersion techniques indicate that emissions
from the main stack had a small impact at the McGill School
monitor. Thus, higher measured TSP concentrations may occur when
the plant is operational, but increased activity at other smelter-
related sources may contribute significantly more particulates to
the McGill School site.
In order to fully examine the available monitoring data,
cumulative frequency distributions of TSP concentrations measured
at other nearby monitoring sites were also derived. Figures 7-3
through 7-5 present the distributions for the North Flat, the
Townsite, and the South Flat sites, respectively. With the
exception of Figure 7-5 (South Flat), these figures show that TSP
concentrations tend to be higher when the smelter is in operation.
The South Flat (Figure 7-5) shows lower concentrations when the
smelter is in operation.
Though no joint frequency distribution of wind direction,
smelter operation, and TSP concentrations was derived, the wind
rose shown in Figure 2-1 indicates a predominance of winds from
the south and south-southwest. Thus, the North Flat monitor to
the north of the plant has concentrations higher than the South
Flat monitor. The McGill School site and the Townsite, which lie
just to the south of the smelter and to the east of the tailings,
may be affected by any number of increased emissions when the
smelter is operational, regardless of wind direction. Table 7-1,
7-5
-------
LTi
Z
o
<
on
o
o
Ł 0.04
o.
IE
oc
0.01
0.009
0.008
0.007
0.006
0.005
0.004
0.003
0.002
120 140 160 180 200 220 240
TSP CONCENTRATION, pg/m3
260 280
Figure 7-3. TSP cumulative frequency distributions tor the North Flat Monitor:
11/77 to 12/79
(smelter operating vs smelter down)
7-6
-------
T
T
V SMELTER OPERATING (26 SAMPLES)
O SMELTER NOT OPERATING (23 SAMPLES)
80 100 120 140 160
TSP CONCENTRATION, ug/mJ
28C
Figure 7-4. TSP cumulative frequency distributions for the Townsite Monitor:
11/77 to 12/5
(smelter operating vs smelter not operating).
7-7
-------
V SMELTER OPERATING (7Z SAMPLES)
O SMELTER NOT OPERATING (34 SAMPLES)
EXCEEDS SECONDARY
NAAQS'6 DAYS/YEAR
180 200 220 240 260 280
TSP CONCENTRATION. ug/mJ
Figure 7-5. TSP cumulative frequency distributions for the South Flat
Monitor: 11/77 to 12/79
(smelter operating vs smelter not operating).
7-8
-------
TABLE 7-1. SUMMARY OF 24-HOUR CONCENTRATIONS OF TSP FOR MONITORS LOCATED NEAR THE MCGILL SMELTER
Smelter operating
Smelter not operating
3
Concentration, pg/m
3
Concentration, pg/m
Moni tori ng
Number of
Number of
si te
Year
observations
Min.
Max.
2nd max.
observations
Min.
Max.
2nd max.
McGill School
1975
40
25
1078
478
13
20
332
82
1976
26
15
358
271
28
22
151
84
1977
50
7
351
291
7
21
72
54
1978
49
15
262
215
3
33
79
42
1979
19
17
88
79
28
19
203
135
North Flat
1977
10
11
585
238
0
1978
58
4
543
340
3
25
62
33
1979
27
8
265
119
32
11
79
73
South Flat
1977
1
19
0
1978
43
2
120
74
2
57
80
1979
29
5
82
71
31
5
234
62
Gal 1egher Gap
1978
14
15
302
182
0
Townsi te
1977
9
25
872
453
0
1979
19
21
621
73
23
9
145
72
-------
which was derived from the same data set as the one used in the
distributions, indicates higher TSP concentrations when the
smelter is operational than when it is nonoperational. The
highest concentrations occurred at the McGill School, North Flat,
and Townsite locations. This was expected based on a review of
the relative source-receptor locations, the major particulate
emitters, and the distribution of winds.
Figures 7-1 through 7-5 indicate the number of days that may
exceed the standards for TSP in a year. The actual number of
violations (shown in Table 7-2), however, are much lower than
those estimated in: the figures. Ambient air. samples are only
taken every sixth cay; therefore, the actual! number of violations
[ i 1
measured would be-expected to be much lower., To interpret the
I
expected exceedanees in terms of the current; monitoring schedule,
the values in the figures must be reduced by, a factor of six.
The conclusion that may be made regarding this analysis is
that TSP concentrations are higher when the ismelter is opera-
tional than when it :is nonoperational. There is no evidence,
however, which clearly indicates that the higher TSP concen-
trations are only due to emissions from the 'main stack. However,
the North Flat monitor is near an expected maximum impact point
(via modeling) and shows more change of violation when the
smelter is operating. Further differentiation of stack versus
other particulate sources must be made to assess various con-
tributions to measured TSP concentrations, (e.g., tracer studies
or particulate identification).
7-10
-------
TABLE 7-2. SUMMARY OF VIOLATIONS OF THE 24-HOUR NAAQS FOR TSP AS MEASURED
AT MONITOR SITES LOCATED NEAR THE KENNECOTT SMELTER AT MCGILL, NEVADA
Moni tor
Period of
Number of violations of NAAQS
si te
record
Primary
Secondary
Total
McGill School
1/1/75 to
12/29/79
9
16
16
North Flat
11/3/77 to
12/29/79
4
7
7
South Flat
11/3/77 to
12/29/79
0
1
1
Gallegher Gap
7/13/78 to
9/29/79
1
2
2
Townsi te
11/3/77 to
12/27/77 and
4/27/79 to
12/29/79
3
3
3
Total
17
29
29
7-11
-------
7.2 WIND DIRECTION VS VIOLATIONS
Descriptions of the 24-hour average wind directions for each
day a violation occurred may yield a clearer Interpretation of
potential contributing sources. Figure 7-6 shows a map of the
McGill area and each monitoring site. Shown at each monitoring
site are an array of arrows indicating the resultant wind direc-
tions (derived from observations made at the Ely Airport) asso-
ciated with each excursion of the NAAQS from 1976 to 1979. The
length of the arrow indicates the number of violations from that
direction, and each direction includes up to|+22.5 degrees of
I
horizontal angle. The predominant feature Oj_ this figure is that
the McGill School and Townsite locations are affected by a variety
i I
of wind directions, which indicates the influence of fugitive
particulate emissions at the smelter and frcm the tailings. The
North Flat site, however, is mostly influenced by the winds from
the south-southwest, which is in the vicinity of nearly all of
I
the particulate emissions. Thus, on a 24-ho|ur basis there are no
clearcut indications'of any particulate sourice differentiation.
Further analyses of these violations using hourly meteoro-
logical data rather than 24-hour averages may better indicate the
dependence of high TSP values on wind direction and windspeed.
Since atmospheric conditions rarely persist for 24 hours, the
analysis shown in Figure 7-6 represents c-nlv average conditions
1
and does not represent short-term influencing events. Thus,
this analysis yields: only a limited interpretation of the most
influential wind directions.
7-12
-------
4374
4373
4372
4371
4370
4369
4368
4367
4366
4365
4364
4363
4362
4361
4360
4359
4 685 686 687 688 689 690 691 692 693 694 695 69
EASTING, km
jre 7-6. Map showing resultant wind directions associated with each
excursion of the NAAQS from 1976 to 1979.
7-13
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7.3 SUMMARY
The reanalysis of the cumulative frequency distribution of
TSP for all monitor sites near the McGill Smelter and attempts to
relate TSP concentrations to potential sources have led to the
conclusion that TSP concentrations are higher when the plant is
operational. Insufficient evidence, however, is available to
differentiate the main stack as the major contributor to these
increased concentrations. When viewed in light of the modeling
analyses, the monitor by monitor evidence suggests that the
Townsite and McGill School site are influenced by the smelter
fugitives, and the North Flat site by the main stack.
7-14
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SECTION 8
CONCLUSIONS
Limited conclusions may be drawn from the independent review
and analysis of the McGill Smelter performed by PEDCo Environ-
mental. Sufficient evidence to differentiate between air quality
impacts of the main stack and other sources of particulate emis-
sions is lacking. Particulate controls for the main stack, the
tailings pond, and fugitive smelter process emissions should be
considered until the interaction of all sources and the impact at
various source locations are better understood.
This review yielded several interpretations of the ambient
TSP concentrations and source-receptor relationships. The dis-
persion modeling indicated that high concentrations on the
eastern mountains were primarily due to emissions from the main
stack. However, only very limited monitoring of TSP on the
terrain has taken place and thus cannot really be used to verify
these high estimated concentrations. Comparisons of concentra-
tions at several monitors indicate higher measured TSP when the
plant is operational. No data adequately support the hypothesis
that the main stack contributes significantly to measured TSP
levels, although they are higher when the smelter is operational.
However, at the North Flat site a combination of modeling and
monitoring analyses seem to indicate that the main stack may be
8-1
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the main contributor to TSP concentrations. Based on the same
analyses, fugitive smelter emissions when the plant is operational
appear to contribute to monitors closer to the plant, i.e., the
Townsite and the McGill School monitors). The monitor cannot
differentiate sources.
Thus, EPA is correct in concluding from modeling and moni-
toring results that the McGill Smelter contributes significantly
to ambient TSP levels. Actual control levels for particulate
sources must be based on modeling and monitoring results that
consider source contribution adequately.
8-2
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TECHNICAL REPORT DATA
(Please read Instructions on llie reverse before tompleunRl
1. REPORT NO. 2
EPA-909/9-80-001
3 RECIPIENT'S ACCESSION NO
4 TITLE AND SUBTITLE
Monitoring and Modeling Analyses of the Kennecott
Corporation Smelter in McGill, Nevada
5 REPORT DATE
March 1981
6 PERFORMING ORGANIZATION CODE
7 AUTHOR(S)
George J. Schewe
8 PERFORMING ORGANIZATION REPORT NO
3450-14
9. PERFORMING ORGANIZATION NAME AND ADDRESS
PEDCo Environmental, Inc.
11499 Chester Road
Cincinnati, Ohio 45246
10 PROGRAM ELEMENT NO
11 CONTRACT/GRANT NO
68-02-3173
Task No. 14
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Region IX
215 Fremont Street
San Francisco, California
13 TYPE OF REPORT AND PERIOO COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
Region IX Project Officer: Linda Larson, Air Technical Branch
16. ABSTRACT
An independent assessment of the particulate control strategy for the
Kennecott Copper Smelter in McGill, Nevada was conducted to support EPA Region IX
in determining whether revisions to the EPA approved .Nevada State Implementation
Plan (SIP) represent an adequate level of control. LThe report presents a review
of information submitted by the State of Nevada and the Kennecott Corporation
regarding the air quality impact of emissions from the smelter; application of
the Valley and Hydrodynamic Models to the smelter; and meteorological data from
the National Weather Service at Yelland Field, Ely, Nevada.! A detailed emission
inventory of total suspended particulate (TSP) sources was~aeveloped for the
area encompassing a 5 mile radius from the smelter to evaluate the air quality
impacts of stack and fugitive particulate emission sources.
17. KEY WORDS AND DOCUMENT ANALYSIS
a DESCRIPTORS
b. IDENTIFIERS/OPEN ENDED TERMS
c COSATi Field/Group
Air pollution control
Copper smelting
Models
Particles
Air quality impact,
Emission inventory
Kennecott Corp., McGill,
Nevada
Hydrodynamic Model,
Valley Model
TSP, Fugitive emissions
13B
11F, 13H
14B
14G
18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21 NO. OF PAGES
136
20 SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9*73)
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