U.S. Department of the Interior

Bureau of Land Management August 200

Pinedale and Rock Springs Field Offices DES-05-0

JONAH INFILL DRILLING PROJECT

DRAFT ENVIRONMENTAL IMPACT STATEMENT

AIR QUALITY IMPACT ANALYSIS SUPPLEMENT
MISSION STATEMENT

It is the mission of the Bureau of Land Management to sustain the health, diversity, and 

productivity of the public lands for the use and enjoyment of present and future 

generations.

BLM/WY/PL-05/009+1310
JONAH INFILL DRILLING PROJECT 

DRAFT ENVIRONMENTAL IMPACT STATEMENT 

AIR QUALITY IMPACT ANALYSIS SUPPLEMENT 

Prepared for 

Bureau of Land Management 

Wyoming State Office 

Cheyenne, Wyoming 

and 

Bureau of Land Management 

Pinedale Field Office 

Pinedale, Wyoming 

and 

Bureau of Land Management 

Rock Springs Field Office 

Rock Springs, Wyoming 

and 

Wyoming Department of Environmental Quality 

Air Quality Division 

Cheyenne, Wyoming 

August 2005 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project i

TABLE OF CONTENTS 

Section Page

1.0 INTRODUCTION ...............................................................................................................1 

2.0 PREFERRED ALTERNATIVE MODELING ANALYSES..............................................3 

2.1 IMPACTS SUMMARY.......................................................................................... 6 

2.2 DIRECT PROJECT IMPACTS.............................................................................. 9 

2.2.1 High Emissions......................................................................................... 10 

2.2.2 Low Emissions.......................................................................................... 11 

2.2.3 Mitigation Scenarios................................................................................. 13 

2.3 CUMULATIVE IMPACTS.................................................................................. 16 

2.3.1 High Emissions......................................................................................... 17 

2.3.2 Low Emissions.......................................................................................... 18 

2.3.3 Mitigation Scenarios................................................................................. 19 

2.4 MITIGATION STRATEGIES.............................................................................. 21 

3.0 EARLY-PROJECT-DEVELOPMENT STAGE MODELING.........................................23 

3.1 IMPACTS SUMMARY........................................................................................ 25 

3.2 DIRECT PROJECT IMPACTS............................................................................ 26 

3.3 CUMULATIVE IMPACTS.................................................................................. 30 

LIST OF TABLES 

Table 1 Preferred Alternative Air Quality Concentrations and Deposition 

Impacts Summary................................................................................................... 7 

Table 2 Preferred Alternative Visibility (Regional Haze) Impacts Summary..................... 8 

Table 3 Example Mitigation Options for the Jonah Infill Drilling Project 

Preferred Alternative ............................................................................................ 22 

Table 4 Early-Project-Development Stage Air Quality Concentrations and 

Deposition Impacts Summary............................................................................... 27 

Table 5 Early-Project-Development Stage Visibility (Regional Haze) Impacts 

Summary............................................................................................................... 28 
 Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project ii

 ACRONYMS AND ABBREVIATIONS

ANC acid neutralizing capacity 

AQRV air quality related value 

AQTSD air quality technical support document 

BLM U.S. Department of Interior, Bureau of Land Management 

DAT data analysis threshold (deposition) 

DEIS draft environmental impact statement 

dv deciview 

EPA U.S. Environmental Protection Agency 

FEIS final environmental impact statement 

FLAG Federal Land Manager’s Air Quality Related Values Workgroup 

FLM Federal Land Manager 

JMHP Jack Morrow Hills Project 

JIDP Jonah Infill Drilling Project 

JIDPA Jonah Infill Drilling Project Area 

LAC level of acceptable change (ANC) 

LOC level of concern (deposition) 

LOP life-of-project 

NAAQS national ambient air quality standard 

NO2 nitrogen dioxide 

NOx oxides of nitrogen 

NPS National Park Service 

PAP Pinedale Anticline Project 

PM particulate matter 

PM10 particulate matter less than 10 microns in diameter 

PM2.5 particulate matter less than 2.5 microns in diameter 

PSD Prevention of Significant Deterioration 

RFFA reasonably foreseeable future actions 

RFD reasonably foreseeable development 

RRP Riley Ridge Project 

SILs Significant Impact Levels 

SO2 sulfur dioxide 

SPP South Piney Project 

TRC TRC Environmental Corporation 

USDA Forest Service U.S. Department of Agriculture, Forest Service 

VOC volatile organic compound 

WAAQS Wyoming ambient air quality standard 

WDEQ-AQD Wyoming Department of Environmental Quality, Air Quality Division 

WDR well development rate (wells per year) 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 1

1.0 INTRODUCTION 

This Air Quality Impact Analysis Supplement (AQIAS) was prepared to summarize additional 

air quality analyses that have been performed for the Bureau of Land Management (BLM) in 

support of the proposed Jonah Infill Drilling Project (JIDP). These analyses are described in 

detail in the Jonah Infill Drilling Project Draft Air Quality Technical Support Document 

Supplement (TRC Environmental Corporation [TRC] 2005). The additional air quality modeling 

analyses supplement the air quality analyses that were performed and presented for a range of 

project alternatives in the Draft Environmental Impact Statement, Jonah Infill Drilling Project, 

Sublette County, Wyoming (DEIS) (BLM 2005) and summarized in detail in the Draft Air 

Quality Technical Support Document for the Jonah Infill Drilling Project Environmental Impact 

Statement (AQTSD) (TRC 2004). 

The additional air quality analyses quantify project-specific and cumulative air quality impacts 

from additional configurations of the proposed JIDP Preferred Alternative which were not 

analyzed as part of the DEIS, and quantify project-specific and cumulative impacts from 

potential emissions which reflect early-project-development stage conditions existing in the 

region surrounding the Jonah Infill Drilling Project area (JIDPA). The additional analyses were 

deemed necessary by the BLM to 1) evaluate alternative potential mitigation strategies for the 

Preferred Alternative in an effort to identify possible project development requirements to reduce 

adverse air quality impacts, and 2) identify maximum early-project-development stage regional 

emissions (i.e., drilling) which could reveal that regional impacts are more severe at this stage 

due to impacts from the development of other regional projects, which had not been adequately 

evaluated. 

The DEIS analyses utilized the CALMET and CALPUFF models to assess impacts from project 

and non-project cumulative air emissions of PM10, PM2.5, NOx, and SO2 on air quality and air 

quality related values (AQRVs) at far-field and mid-field locations and within the JIDPA. Farfield pollutant impacts were assessed at Prevention of Significant Deterioration (PSD) Class I 

areas (Bridger, Fitzpatrick, Teton, and Washakie Wilderness Areas and Grand Teton and 

Yellowstone National Parks), and at sensitive PSD Class II areas (Popo Agie Wilderness Area 
 Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 2

and Wind River Roadless Area). Far-field analyses included impact assessments of 

concentration, visibility (regional haze), atmospheric deposition, and lake acidity (at sensitive 

lakes within the Wilderness Areas). These included Black Joe, Deep, Hobbs, Lazy Boy, and 

Upper Frozen lakes within the Bridger Wilderness Area, Ross Lake in the Fitzpatrick Wilderness 

Area, and Lower Saddlebag Lake in the Popo Agie Wilderness Area. Mid-field visibility 

(regional haze) impact analyses were performed for the Wyoming regional community locations 

of Big Piney, Big Sandy, Boulder, Bronx, Cora, Daniel, Farson, LaBarge, Merna, and Pinedale 

although these communities are classified as PSD Class II areas where no visibility protection 

exists under local, State, or Federal law. In-field analyses included assessments of concentration 

impacts within the JIDPA. 

The Preferred Alternative modeling analyses presented in this document are directly comparable 

to the analyses conducted for the DEIS. Unlike the Preferred Alternative modeling analyses, 

early-project-development stage modeling is not directly comparable to either the analyses 

conducted for the DEIS or the Preferred Alternative modeling analyses. 
 Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 3

2.0 PREFERRED ALTERNATIVE MODELING ANALYSES 

The Preferred Alternative for the JIDP consists of the development of 3,100 new natural gas 

wells on approximately 8,316 acres of new surface disturbance in the JIDPA, and assumes 

approximately 50% directionally drilled wells and 50% straight hole wells. Modeling scenarios 

were presented in the DEIS for Alternative F that approximated the potential impacts for the 

Preferred Alternative in 2017, presumed to be the peak emissions year. Assumptions used in that 

analysis are described in detail in the original AQTSD (TRC 2004). Configurations of the 

Preferred Alternative that are different from those analyzed in the DEIS have been modeled to 

provide a representation of a range of impacts possible under the Preferred Alternative. A low 

emissions scenario and a high emissions scenario were modeled, as were four potential levels of 

air pollution mitigation through emission reductions within the JIDPA. The modeling analyses 

for these additional configurations of the Preferred Alternative follow the methodologies 

described in the original AQTSD (TRC 2004), and are directly comparable to the analyses 

conducted for the DEIS (BLM 2005). 

The low emissions scenario placed all drill rig engines at U.S. Environmental Protection Agency 

(EPA) Tier 2 emission levels, and the high emissions scenario included 80% of drill rig engines 

at Tier 0 emission levels (assumed equivalent to emission factors contained in EPA’s AP-42 

emission factor guidance document) (EPA 1995) and 20% at Tier 1 emission levels. The four 

mitigation scenarios assumed a specific emissions reduction from the JIDP high emissions 

configuration at a well development rate (WDR) of 250. Emission reductions of 20%, 40%, 

60%, and 80% were modeled separately. 

As in the DEIS modeling, the modeling scenarios were based upon anticipated field 

characteristics in year 2017. Only project emissions differed from those modeled for the DEIS; 

non-project emissions remained the same. To maintain consistency and comparability with the 

results reported in the original DEIS (BLM 2005) and AQTSD (TRC 2004), non-project regional 

emissions were modeled as they were in the DEIS, and as described in detail in the AQTSD 

Predicted pollutant concentrations were compared to applicable ambient air quality standards, 

PSD Class I and Class II increments, and proposed PSD Class I significance levels (SILs), and 
 Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 4

were used to assess potential impacts to AQRVs – atmospheric deposition and visibility 

(regional haze) – at sensitive PSD Class I and II areas. The PSD demonstrations serve 

information purposes only and do not constitute a regulatory PSD Increment consumption 

analysis, which may be completed as necessary by Wyoming Department of Environmental 

Quality – Air Quality Division (WDEQ-AQD). Ambient background concentrations were added 

to modeled concentrations for comparison to ambient air quality standards. No ambient 

background was added to modeled concentrations for comparison to PSD Class I and II 

Increments. 

The National Park Service (NPS) (2001) has identified Deposition Analysis Thresholds (DATs) 

for total nitrogen (N) and sulfur (S) deposition in the western U.S. as 0.005 kilograms per 

hectare per year (kg/ha-year) for both N and S. The DAT is used as an analysis threshold for 

evaluating potential impacts from project-related emissions. The exceedences of this threshold 

trigger a management concern but are not necessarily indicative of an adverse impact (NPS 

2004). The U.S. Department of Agriculture, Forest Service (USDA Forest Service) has defined 

thresholds below which no adverse impacts from atmospheric deposition are likely (Fox et al. 

1989). These thresholds (herein referred to as levels of concern), defined as 5 kg/ha-yr for S and 

3 kg/ha-yr for N, are used for comparison of potential impacts from cumulative source 

emissions. It is understood that the USDA Forest Service no longer considers these levels of 

concern to be protective; however, in the absence of alternative Federal Land Manager (FLM)-

approved values, comparisons with these values were made. 

The USDA Forest Service Rocky Mountain Region has also developed a screening method 

(USDA Forest Service 2000) that identifies a Limit of Acceptable Change (LAC) in lake 

chemistry. The LACs are 1) no more than a 10% change in acid-neutralizing capacity (ANC) for 

lakes with an existing ANC of 25 microequivalents per liter (μeq/l) or greater and 2) no more 

than a 1-μeq/l change for extremely acid-sensitive lakes where the existing ANC is below 

25 μeq/l. Of the seven lakes identified by the USDA Forest Service as acid-sensitive, Upper 

Frozen and Lazy Boy lakes are considered extremely acid-sensitive. 
 Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 5

Visibility impacts discussed herein were estimated using methodologies selected by BLM; the

Jonah Infill Drilling Project Draft Air Quality Technical Support Document Supplement (TRC 

2005) documents the results from methodologies favored by other agencies. Potential changes in 

regional haze at PSD Class I and sensitive PSD Class II areas were estimated by comparing 

CALPUFF modeled impacts to background visibility conditions in PSD Class I and sensitive 

PSD Class II areas. This comparison was performed using two different representations of 

background visibility conditions. One method used visibility values provided in the FLAG 

Report for each Class I area to represent natural background visibility. The second method used 

estimated background visibility values from an analysis of recent long-term monitored data 

(1988–2002) from the IMPROVE program. This analysis consisted of estimating visibility 

parameters for representative Class I areas corresponding to the monitoring period of record 

quarterly average of the 20% best visibility days. Background visibility data monitored at the 

Class I Bridger Wilderness Area, an area more pristine than populated residential areas (i.e., 

lacking suburban/rural emissions such as those from traffic and wood stoves), were used to 

estimate potential visibility impairment at Wyoming regional community locations. These data 

were used because no visibility monitoring has been conducted in the populated areas of the 

region. Since visibility impacts are calculated as percent increases of modeled concentrations 

above background values, the use of a more pristine background likely result in an overestimate 

of potential visibility impacts at these locations. 

The BLM considers a 1.0 deciview (dv) change as a significant adverse impact, and if predicted 

visibility impacts are above this threshold, factors such as magnitude of dv change, frequency, 

seasonal variations, and meteorological conditions may be considered when assessing the 

significance of predicted impacts. Although BLM utilizes this 1.0-dv threshold, there are no 

applicable local, state, tribal, or federal regulatory visibility standards. It is the responsibility of 

the FLM or Tribal government responsible for that land to determine when adverse impacts are 

significant or not, and these may differ from BLM levels for significant adverse impacts. Other 

federal agencies use a 0.5-dv change as a screening threshold for significance. The USDA 

Forest Service and NPS compare direct project impacts to the 0.5-dv level, and those 
 Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 6

comparisons are included in the Jonah Infill Drilling Project Draft Air Quality Technical 

Support Document Supplement (TRC 2005). 

2.1 IMPACTS SUMMARY 

Tables 1 and 2 provide an overall summary of the predicted impacts from three of the ten 

additional configurations analyzed for the Preferred Alternative. These three scenarios, a high 

emissions case at WDR250, a low emissions case at a WDR250, and a high emissions mitigation 

case with an 80 percent emission reduction at a WDR250, are representative of the full range of 

impacts for those 10 configurations. Table 1 provides a summary of the potential concentration 

and deposition impacts from these configurations of the Preferred Alternative. Table 2 provides 

a summary of the potential impacts to visibility (regional haze) for these scenarios. Results 

summaries shown in green (normal text) in these tables indicate that potential impacts are below 

ambient air quality standards, PSD increments, significance threshold values, and levels of 

concern. Results summaries shown in red (bold text) indicate that potential impacts are above 

these levels. A complete disclosure of all modeled impacts for each additional scenario modeled 

for the Preferred Alternative including additional mitigation runs (60%, 40%, and 20% emissions 

reductions) and alternate WDRs (150, 75), and a disclosure of days of visibility impairment 

greater than 0.5-dv (an alternate visibility threshold utilized by other FLMs) for all analyzed 

scenarios are provided in the Jonah Infill Drilling Project Draft Air Quality Technical Support 

Document Supplement (TRC 2005). A discussion of both the direct impacts and cumulative 

impacts from the analyzed Preferred Alternative scenarios are provided in the following sections. 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 7

Table 1 Preferred Alternative Air Quality Concentrations and Deposition Impacts Summary 

Air Quality 

Component Criteria 

Source Group 

& Impact Area 

Preferred Alternative: 

WDR250 

High Emissions Case 

Preferred Alternative: 

WDR250 

Low Emissions Case 

Preferred Alternative: 

WDR250 

80% Mitigation Case 

Project: 

In-Field 

PM10< NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

Cumulative: 

In-Field 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

Project: 

Far-Field 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

Air Quality 

Standards 

Cumulative: 

Far-Field 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PSD Class I 

Increments 1

Cumulative: 

Far-Field 

PM10 < increment 

NO2 < increment 

SO2 < increment

PM10 < increment 

NO2 < increment 

SO2 < increment 

PM10 < increment 

NO2 < increment 

SO2 < increment 

Concentrations 

PSD Class II 

Increments 1

Cumulative: 

Far-Field 

PM10 < increment 

NO2 < increment 

SO2 < increment 

PM10 < increment 

NO2 < increment 

SO2 < increment 

PM10 < increment 

NO2 < increment 

SO2 < increment 

N Deposition Total: 

Far-Field N < LOC, All Areas N < LOC, All Areas N < LOC, All Areas 

S Deposition Total: 

Far-Field S < LOC, All Areas S < LOC, All Areas S < LOC, All Areas 

Project: 

Far-Field ANC Change < LAC, All Lakes ANC Change < LAC, All Lakes ANC Change < LAC, All Lakes 

Atmospheric 

Deposition 

Sensitive 

Lakes Cumulative: 

Far-Field ANC Change < LAC, All Lakes ANC Change < LAC, All Lakes ANC Change < LAC, All Lakes 

 

1

 The PSD demonstrations serve information purposes only and do not constitute a regulatory PSD Increment consumption analysis.
 Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 8

Table 2 Preferred Alternative Visibility (Regional Haze) Impacts Summary 

Air Quality Component Impact Area Source Group 

Preferred Alternative: 

WDR250 

High Emissions Case 

Preferred Alternative: 

WDR250 

Low Emissions Case 

Preferred Alternative: 

WDR250 

80% Mitigation Case 

Project 

Bridger WA, >1.0-dv 31 days, max dv = 6.44 

Fitzpatrick WA, >1.0-dv 3 days, max dv = 1.54 

Popo Agie WA, >1.0-dv 2 days, max dv = 1.36 

Wind River RA, >1.0-dv 1 days, max dv = 1.22 

Grand Teton NP, >1.0-dv 0 days, max dv = 0.66 

Teton WA, >1.0-dv 0 days, max dv = 0.28 

Yellowstone NP, >1.0-dv 0 days, max dv = 0.31 

Washakie WA, >1.0-dv 0 days, max dv = 0.48

Bridger WA, >1.0-dv 9 days, max dv = 3.26 

Fitzpatrick WA, >1.0-dv 0 days, max dv = 0.61 

Popo Agie WA, >1.0-dv 0 days, max dv = 0.59 

Wind River RA, >1.0-dv 0 days, max dv = 0.50 

Grand Teton NP, >1.0-dv 0 days, max dv = 0.31 

Teton WA, >1.0-dv 0 days, max dv = 0.14 

Yellowstone NP, >1.0-dv 0 days, max dv = 0.15 

Washakie WA, >1.0-dv 0 days, max dv = 0.23

Bridger WA, >1.0-dv 3 days, max dv = 1.66 

Fitzpatrick WA, >1.0-dv 0 days, max dv = 0.33 

Popo Agie WA, >1.0-dv 0 days, max dv = 0.29 

Wind River RA, >1.0-dv 0 days, max dv = 0.26 

Grand Teton NP, >1.0-dv 0 days, max dv = 0.14 

Teton WA, >1.0-dv 0 days, max dv = 0.06 

Yellowstone NP, >1.0-dv 0 days, max dv = 0.06 

Washakie WA, >1.0-dv 0 days, max dv = 0.10

PSD Class I and 

Sensitive Class II 

Areas 

 

Cumulative 

Bridger WA, >1.0-dv 39 days, max dv = 6.82 

Fitzpatrick WA, >1.0-dv 3 days, max dv = 1.58 

Popo Agie WA, >1.0-dv 6 days, max dv = 1.67 

Wind River RA, >1.0-dv 5 days, max dv = 1.54 

Grand Teton NP, >1.0-dv 0 days, max dv = 0.83 

Teton WA, >1.0-dv 0 days, max dv = 0.34 

Yellowstone NP, >1.0-dv 0 days, max dv = 0.40 

Washakie WA, >1.0-dv 0 days, max dv = 0.58

Bridger WA, >1.0-dv 15 days, max dv = 3.78 

Fitzpatrick WA, >1.0-dv 0 days, max dv = 0.85 

Popo Agie WA, >1.0-dv 0 days, max dv = 0.97 

Wind River RA, >1.0-dv 2 days, max dv = 1.19 

Grand Teton NP, >1.0-dv 0 days, max dv = 0.49 

Teton WA, >1.0-dv 0 days, max dv = 0.23 

Yellowstone NP, >1.0-dv 0 days, max dv = 0.25 

Washakie WA, >1.0-dv 0 days, max dv = 0.33

Bridger WA, >1.0-dv 6 days, max dv = 2.62 

Fitzpatrick WA, >1.0-dv 0 days, max dv = 0.57 

Popo Agie WA, >1.0-dv 0 days, max dv = 0.75 

Wind River RA, >1.0-dv 0 days, max dv = 0.96 

Grand Teton NP, >1.0-dv 0 days, max dv = 0.35 

Teton WA, >1.0-dv 0 days, max dv = 0.17 

Yellowstone NP, >1.0-dv 0 days, max dv = 0.18 

Washakie WA, >1.0-dv 0 days, max dv = 0.23

Project 

Big Piney, >1.0-dv 18 days, max dv = 3.93 

Big Sandy, >1.0-dv 62 days, max dv = 5.76 

Boulder, >1.0-dv 33 days, max dv = 4.58 

Bronx, >1.0-dv 9 days, max dv = 3.82 

Cora, >1.0-dv 14 days, max dv = 6.70 

Daniel, >1.0-dv 16 days, max dv = 5.50 

Farson, >1.0-dv 13 days, max dv = 4.88 

Labarge, >1.0-dv 6 days, max dv = 2.59 

Merna, >1.0-dv 5 days, max dv = 1.64 

Pinedale, >1.0-dv 21 days, max dv = 8.48 

Big Piney, >1.0-dv 4 days, max dv = 1.89 

Big Sandy, >1.0-dv 21 days, max dv = 2.92 

Boulder, >1.0-dv 10 days, max dv = 2.30 

Bronx, >1.0-dv 1 days, max dv = 1.60 

Cora, >1.0-dv 1 days, max dv = 3.03 

Daniel, >1.0-dv 1 days, max dv = 2.42 

Farson, >1.0-dv 5 days, max dv = 2.21 

Labarge, >1.0-dv 2 days, max dv = 1.27 

Merna, >1.0-dv 0 days, max dv = 0.75 

Pinedale, >1.0-dv 3 days, max dv = 4.07 

Big Piney, >1.0-dv 0 days, max dv = 0.92

Big Sandy, >1.0-dv 4 days, max dv = 1.45 

Boulder, >1.0-dv 2 days, max dv = 1.10 

Bronx, >1.0-dv 0 days, max dv = 0.89 

Cora, >1.0-dv 1 days, max dv = 1.75 

Daniel, >1.0-dv 1 days, max dv = 1.37 

Farson, >1.0-dv 1 days, max dv = 1.19 

Labarge, >1.0-dv 0 days, max dv = 0.57 

Merna, >1.0-dv 0 days, max dv = 0.35 

Pinedale, >1.0-dv 1 days, max dv = 2.37

Visibility 

(Regional Haze) 

Wyoming 

Regional 

Communities 

Cumulative 

Big Piney, >1.0-dv 36 days, max dv = 4.32 

Big Sandy, >1.0-dv 74 days, max dv = 6.18 

Boulder, >1.0-dv 40 days, max dv = 5.58 

Bronx, >1.0-dv 15 days, max dv = 3.88 

Cora, >1.0-dv 17 days, max dv = 6.77 

Daniel, >1.0-dv 23 days, max dv = 5.56 

Farson, >1.0-dv 21 days, max dv = 5.05 

Labarge, >1.0-dv 16 days, max dv = 3.97 

Merna, >1.0-dv 10 days, max dv = 1.93 

Pinedale, >1.0-dv 27 days, max dv = 8.56 

Big Piney, >1.0-dv 19 days, max dv = 2.57 

Big Sandy, >1.0-dv 32 days, max dv = 3.48 

Boulder, >1.0-dv 20 days, max dv = 3.60 

Bronx, >1.0-dv 1 days, max dv = 1.68 

Cora, >1.0-dv 7 days, max dv = 3.13 

Daniel, >1.0-dv 11 days, max dv = 2.52 

Farson, >1.0-dv 11 days, max dv = 2.68 

Labarge, >1.0-dv 11 days, max dv = 2.85 

Merna, >1.0-dv 4 days, max dv = 1.11 

Pinedale, >1.0-dv 8 days, max dv = 4.18 

Big Piney, >1.0-dv 13 days, max dv = 2.28 

Big Sandy, >1.0-dv 12 days, max dv = 2.13 

Boulder, >1.0-dv 9 days, max dv = 3.09 

Bronx, >1.0-dv 0 days, max dv = 0.97 

Cora, >1.0-dv 2 days, max dv = 1.86 

Daniel, >1.0-dv 2 days, max dv = 1.47 

Farson, >1.0-dv 10 days, max dv = 1.87 

Labarge, >1.0-dv 6 days, max dv = 2.30 

Merna, >1.0-dv 1 days, max dv = 1.03 

Pinedale, >1.0-dv 6 days, max dv = 2.50 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 9

2.2 DIRECT PROJECT IMPACTS 

Direct impacts are the those potential impacts solely from proposed project sources. In this 

analysis, ten additional configurations of the Preferred Alternative were modeled to provide a 

representation of the range of potential direct impacts under the Preferred Alternative. As 

described in earlier, these ten configurations provide a representation of the direct impacts which 

could occur from a high emissions case, a low emissions case, and four mitigation scenarios 

which assume varying levels of emission reduction from JIDPA sources at the high emissions 

case. Mitigation scenarios were based on emission reduction percentages of 20, 40, 60 and 80 

percent from the JIDP high emissions configuration. Results from three of these ten scenarios 

are presented here: the high emissions case; the low emissions case; and the high emissions case 

with an 80 percent emission reduction. The 80% emission reduction is assumed to occur fieldwide and not specific to any individual field activity or operation. These three scenarios are 

considered representative of the range of impacts from the ten analyzed scenarios, for which 

complete results are provided in the Jonah Infill Drilling Project Draft Air Quality Technical 

Support Document Supplement (TRC 2005). 

 Far-field pollutant impacts were assessed at the PSD Class I areas (Bridger, Fitzpatrick, Teton, 

and Washakie Wilderness Areas and Grand Teton and Yellowstone National Parks), and at the 

sensitive Class II Popo Agie Wilderness Area and Wind River Roadless Area. Far-field analyses 

include impact assessments of concentration, visibility (regional haze), atmospheric deposition, 

and lake acidity (at sensitive lakes within the Wilderness Areas). Mid-field visibility (regional 

haze) impact analyses were performed for the Wyoming regional community locations of Big 

Piney, Big Sandy, Boulder, Bronx, Cora, Daniel, Farson, LaBarge, Merna, and Pinedale. In-field 

analyses include impact assessments of concentration within the JIDPA. 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 10

2.2.1 High Emissions

Far-field Impacts

Direct project impacts from Preferred Alternative high emissions scenario source emissions were 

below the applicable ambient air quality standards and PSD increments (Table 1). NO2, SO2, and 

PM10 concentrations were greater than PSD Class I SILs for these pollutants within the Bridger 

Wilderness Area. PM10 concentrations were greater than PSD Class I SIL within the Fitzpatrick 

Wilderness Area. These SILs are proposed by EPA as an indicator of significance of New 

Source Review projects to determine additional analysis requirements. PM10 was below the 

proposed SILs at all sensitive areas except the Bridger and Fitzpatrick Wilderness Areas, and 

NO2, and SO2 concentrations were below the SILS at all sensitive areas except the Bridger 

Wilderness Area. 

 

Direct project source emissions from the Preferred Alternative high emissions case would result 

in an increase in ANC less than any LAC at all analyzed acid-sensitive lakes. The maximum S 

deposition impacts were predicted to be above the 0.005 kg/ha-yr DAT at the Bridger 

Wilderness Area (0.008 kg/ha-yr) and below the DAT at all other sensitive PSD Class I and 

Class II areas. The maximum N impacts were predicted to be above the 0.005 kg/ha-yr 

threshold at the Bridger Wilderness Area, Fitzpatrick Wilderness Area, Popo Agie Wilderness 

Area, and Wind River Roadless Area, and below the DAT at all other sensitive areas. The 

maximum predicted N deposition impacts are 0.077, 0.006, 0.035, and 0.021 kg/ha-yr at the 

Bridger, Fitzpatrick, and Popo Agie Wilderness Areas, and Wind River Roadless Area, 

respectively. The exceedences of this threshold trigger a management concern but are not 

necessarily indicative of an adverse impact (NPS 2004). 

Direct visibility (regional haze) impacts were predicted to be above the "just noticeable visibility 

change" (1.0-dv) threshold at the Bridger, Fitzpatrick and Popo Agie Wilderness Areas, and at 

the Wind River Roadless Area using both the FLAG and IMPROVE background visibility data, 

and below the threshold at all other sensitive areas (Table 2). The highest frequency of predicted 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 11

visibility impacts occurred at the Bridger Wilderness where there were 23 days per year (FLAG) 

and 31 days per year (IMPROVE) when visibility impacts where predicted to be above the 1.0-

dv threshold. The maximum dv change was estimated as 5.9 dv (FLAG) and 6.4 dv 

(IMPROVE). 

Mid-field Impacts

Model results for the Preferred Alternative high emission scenario indicate impacts above the 

1.0-dv threshold at all nearby Wyoming community locations (Table 2). Note that the 

comparison to the 1.0-dv threshold is for information only; because these communities are 

within areas classified as PSD Class II, no visibility protection exists under local, State, or 

Federal law. The highest frequency of predicted visibility impacts occurred at Big Sandy where 

they were 56 days (FLAG) and 62 days (IMPROVE) estimated to be above the 1.0-dv threshold. 

The maximum dv change, 7.7 dv (FLAG), and 8.5 dv (IMPROVE) was predicted to occur at 

Pinedale. 

In-field Impacts 

Direct impacts of NO2, SO2, PM10, and PM2.5 within the JIDPA resulting from Preferred 

Alternative high emissions scenario source emissions, when added to appropriate background 

concentrations, were predicted to be less than all applicable ambient air quality standards. 

2.2.2 Low Emissions

Far-field Impacts

Direct impacts from Preferred Alternative low emissions scenario source emissions were less 

than all applicable ambient air quality standards and PSD increments (Table 1). Potential NO2 

and PM10 concentrations were greater than the proposed PSD Class I SILs at the Bridger 

Wilderness Area and were below the SILs at all other sensitive areas. These SILs are proposed 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 12

by EPA as an indicator of significance of New Source Review projects to determine additional 

analysis requirements. 

Direct project source emissions from the Preferred Alternative low emissions case would result 

in an increase in ANC less than any LAC at all analyzed acid-sensitive lakes. The maximum S 

deposition impacts were predicted to be below the DAT at all sensitive PSD Class I and Class II 

areas. The maximum N impacts were predicted to be above the 0.005 kg/ha-yr threshold at the 

Bridger Wilderness Area, Popo Agie Wilderness Area, and Wind River Roadless Area, and 

below the DAT at all other sensitive areas. The maximum predicted N deposition impacts are 

0.033, 0.016, and 0.010 kg/ha-yr at the Bridger and Popo Agie Wilderness Areas, and Wind 

River Roadless Area, respectively. 

Direct visibility (regional haze) impacts were predicted to be above the "just noticeable visibility 

change" (1.0-dv) threshold at the Bridger Wilderness Area using both the FLAG and IMPROVE 

background visibility data, and below the threshold at all other sensitive areas (Table 2). There 

were 9 days per year (FLAG and IMPROVE) when visibility impacts where predicted to be 

above the 1.0-dv threshold. The maximum dv change was estimated as 3.0 dv (FLAG) and 3.3 

dv (IMPROVE). 

Mid-field Impacts

Modeling results for the Preferred Alternative low emission scenario indicate impacts above the 

1.0-dv threshold at all nearby Wyoming community locations with the exception of Merna 

(Table 2). The highest frequency of predicted visibility impacts occurred at Big Sandy where 

they were 17 days (FLAG) and 21 days (IMPROVE) estimated to be above the 1.0-dv threshold. 

The maximum dv change, 3.6 dv (FLAG), and 4.1 dv (IMPROVE) was predicted to occur at 

Pinedale. 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 13

In-field Impacts 

Direct impacts of NO2, SO2, PM10, and PM2.5 within the JIDPA resulting from Preferred 

Alternative low emissions scenario source emissions, when added to appropriate background 

concentrations, were predicted to be less than all applicable ambient air quality standards. 

2.2.3 Mitigation Scenarios

A complete description of mitigation scenario results, including tables, is provided in the Jonah 

Infill Drilling Project Draft Air Quality Technical Support Document Supplement (TRC 2005). 

Far-field Impacts

Direct impacts from the Preferred Alternative mitigation scenarios would be below all applicable 

ambient air quality standards and PSD increments. Under the 20 percent emissions reduction 

scenario, NO2, SO2 and PM10 concentrations were greater than the proposed PSD Class I SILs at 

the Bridger Wilderness Area, PM10 concentrations were greater than the PSD Class I SIL at the 

Fitzpatrick Wilderness Area, and concentrations of all other pollutants were below the SILs at all 

other sensitive areas. For the 40 percent emissions reduction scenario, NO2, SO2 and PM10

concentrations were greater than the proposed PSD Class I SILs at the Bridger Wilderness Area 

and were below the SILs at all other sensitive areas. The 60 percent emissions reduction 

scenario modeling results indicated potential NO2 and PM10 concentrations above the proposed 

PSD Class I SILs at the Bridger Wilderness Area and below the SILs at all other sensitive areas. 

The 80 percent emissions reduction scenario modeling indicated potential PM10 concentrations 

above the proposed PSD Class I SILs at the Bridger Wilderness Area and below the SILs at all 

other sensitive areas. These SILs are proposed by EPA as an indicator of significance of New 

Source Review projects to determine additional analysis requirements. 

Direct project impacts from all of the mitigation scenarios would result in an increase in ANC 

less than the LAC at all analyzed acid-sensitive lakes. The predicted maximum S deposition 

impacts for the 20 percent emission reduction scenario were predicted to be above the DAT at 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 14

the Bridger Wilderness (0.006 kg/ha-yr) and below the DAT at all other sensitive PSD Class I 

and Class II areas. All other scenarios predicted S deposition impacts below the DAT at all 

sensitive areas. The maximum N deposition impacts for the 20 percent emissions reduction case 

were predicted to be above the DAT at the Bridger Wilderness Area (0.062 kg/ha-yr), Popo Agie 

Wilderness Area (0.028 kg/ha-yr) and Wind River Roadless Area (0.017 kg/ha-yr), and below 

the DAT at all other sensitive areas. The maximum predicted N impacts for the 40 percent 

emissions reduction case were above the DAT at the Bridger Wilderness (0.046 kg/ha-yr), Popo 

Agie Wilderness (0.021 kg/ha-yr) and Wind River Roadless Area (0.013 kg/ha-yr). The 

maximum predicted N impacts for the 60 percent emissions reduction case were above the DAT 

at the Bridger Wilderness (0.031 kg/ha-yr), Popo Agie Wilderness (0.014 kg/ha-yr) and Wind 

River Roadless Area (0.009 kg/ha-yr), and for the 80 percent emissions reduction case N 

deposition impacts were predicted above the DAT at the Bridger Wilderness (0.015 kg/ha-yr) 

and Popo Agie Wilderness (0.007 kg/ha-yr). 

Direct visibility (regional haze) impacts for the 20 percent emissions reduction case were 

predicted to be above the "just noticeable visibility change" (1.0-dv) threshold at the Bridger, 

Fitzpatrick and Popo Agie Wilderness Areas, and below the threshold at all other sensitive areas. 

The highest frequency of predicted visibility impacts occurred at the Bridger Wilderness where 

there were 19 days per year (FLAG) and 20 days per year (IMPROVE) when visibility impacts 

where predicted to be above the 1.0-dv threshold, with the maximum dv change estimated as 5.0 

dv (FLAG) and 5.5 dv (IMPROVE). Direct visibility impacts for the 40 percent emissions 

reduction case were predicted to be above the 1.0-dv threshold at the Bridger Wilderness Area 

using both the FLAG and IMPROVE background visibility data. The highest frequency of 

predicted visibility impacts occurred at the Bridger Wilderness where there were 14 days per 

year (FLAG) and 15 days per year (IMPROVE) when visibility impacts where predicted to be 

above the 1.0-dv threshold, with the maximum dv change estimated as 4.0 dv (FLAG) and 4.3 dv 

(IMPROVE). Direct visibility impacts for the 60 percent emissions reduction case were 

predicted to be above the 1.0-dv threshold at the Bridger Wilderness Area and at the Wind River 

Roadless Area. The highest frequency of predicted visibility impacts occurred at the Bridger 

Wilderness where there were 9 days per year, using both FLAG and IMPROVE data, when 

visibility impacts where predicted to be above the threshold, with the maximum dv change 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 15

estimated as 2.8 dv (FLAG) and 3.1 dv (IMPROVE). Direct visibility impacts for the 80 

percent emissions reduction case were predicted to be above the 1.0-dv threshold only at the 

Bridger Wilderness using both the FLAG and IMPROVE background visibility data (2 and 3 

days per year, respectively), with the maximum dv change estimated as 1.5 dv (FLAG) and 1.7 

dv (IMPROVE). 

Mid-field Impacts

Modeling results for the Preferred Alternative 20 percent emissions reduction mitigation 

scenario indicated that visibility impacts were above the 1.0-dv threshold at all nearby Wyoming 

community locations with the highest frequency of predicted visibility impacts above the 1.0-dv 

threshold at Big Sandy (38 days per year – FLAG and 45 days per year – IMPROVE). The 

maximum dv change of 6.5 dv (FLAG), and 7.3 dv (IMPROVE) was predicted to occur at 

Pinedale. The 40 percent emissions reduction case indicated impacts above the threshold at all 

areas with the maximum number of days per year at Big Sandy (28 days – FLAG, and 27 days – 

IMPROVE) and the maximum dv at Pinedale (5.3 dv – FLAG, 5.9 dv – IMPROVE). The 60 

percent emissions reduction case indicated impacts above the threshold at all areas except Merna 

with the maximum number of days per year at Big Sandy (17 days– FLAG, and 19 days – 

IMPROVE) and the maximum dv at Pinedale (3.8 dv – FLAG, 4.3 dv – IMPROVE). The 80 

percent emissions reduction scenario indicated impacts above the visibility threshold at six of the 

analyzed ten areas with the maximum number of days per year at Big Sandy (1 days– FLAG, and 

4 days – IMPROVE) and the maximum dv at Pinedale (2.1 dv – FLAG, 2.4 dv – IMPROVE). 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 16

In-field Impacts 

Direct impacts of NO2, SO2, PM10, and PM2.5 within the JIDPA resulting from Preferred 

Alternative mitigation scenarios, when added to appropriate background concentrations, were 

predicted to be less than all applicable ambient air quality standards. 

2.3 CUMULATIVE IMPACTS 

Cumulative impacts were analyzed for additional configurations of the Preferred Alternative 

(described in greater detail earlier in this section) in combination with other non-project regional 

sources. Cumulative analyses include project impacts plus impacts from permitted sources, 

reasonably foreseeable development (RFD), and reasonably foreseeable future actions (RFFA) 

which were projected to exist after a specified date and would be located within a defined 

regional area (see TRC 2004 for further detail). All air emissions sources within the study 

domain were not explicitly modeled; some sources were considered to already be included 

ambient air background values. The additional configurations analyzed included a low 

emissions scenario, a high emissions scenario, and four mitigation scenarios at 20%, 40%, 60%, 

and 80% emission reductions from the high emission WDR250 scenario. A complete 

description of mitigation scenario results, including tables, is provided in TRC (2005). 

Cumulative far-field pollutant impacts were assessed at the PSD Class I areas and at the sensitive 

PSD Class II Areas. Similar to the analysis of direct project impacts, far-field analyses included 

impact assessments of concentration, visibility (regional haze), atmospheric deposition, and lake 

acidity, mid-field visibility impact analyses were performed for the Wyoming regional 

community locations, and in-field analyses included impact assessments of concentration within 

the JIDPA. 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 17

2.3.1 High Emissions

Far-field Impacts

Cumulative impacts resulting from Preferred Alternative high emissions scenario source 

emissions would be below all applicable ambient air quality standards and PSD increments. 

Cumulative project and non-project source emissions from the Preferred Alternative high 

emissions case would result in an increase in ANC less than any LAC at all acid-sensitive lakes. 

Total S and N deposition impacts would not exceed the USDA Forest Service levels of concern 

(5 kg/ha-yr for S and 3 kg/ha-yr for N). It is understood that the USDA Forest Service no longer 

considers these levels of concern to be protective; however, in the absence of alternative FLMapproved values, comparisons with these values were made. 

Cumulative visibility (regional haze) impacts were predicted to be above the "just noticeable 

visibility change" (1.0-dv) threshold at the Bridger, Fitzpatrick and Popo Agie Wilderness Areas, 

and at the Wind River Roadless Area using both the FLAG and IMPROVE background visibility 

data, and below the threshold at all other sensitive areas. The highest frequency of predicted 

visibility impacts occurred at the Bridger Wilderness where there were 32 days per year (FLAG) 

and 39 days per year (IMPROVE) when visibility impacts where predicted to be above the 1.0-

dv threshold. The maximum dv change was estimated as 6.3 dv (FLAG) and 6.8 dv 

(IMPROVE). 

Mid-field Impacts

Cumulative modeling results for the Preferred Alternative high emission scenario indicate 

impacts above the 1.0-dv threshold at all nearby Wyoming community locations. The highest 

frequency of predicted visibility impacts occurred at Big Sandy where they were 64 days 

(FLAG) and 74 days (IMPROVE) estimated to be above the 1.0-dv threshold. The maximum dv 

change, 7.7 dv (FLAG), and 8.6 dv (IMPROVE) was predicted to occur at Pinedale. 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 18

In-field Impacts 

Direct impacts of NO2, SO2, PM10, and PM2.5 within the JIDPA resulting from Preferred 

Alternative high emissions scenario source emissions and non-project emissions, when added to 

appropriate background concentrations, were predicted to be less than all applicable ambient air 

quality standards. 

2.3.2 Low Emissions

Far-field Impacts

Cumulative impacts resulting from Preferred Alternative low emissions scenario source 

emissions would be below all applicable ambient air quality standards and PSD increments. 

Cumulative impacts for the Preferred Alternative low emissions case would result in an increase 

in ANC less than any LAC at all acid-sensitive lakes. Total S and N deposition impacts would 

not exceed the USDA Forest Service levels of concern. 

Cumulative visibility (regional haze) impacts were predicted to be above the 1.0-dv threshold at 

the Bridger Wilderness Area and Wind River Roadless Area using both the FLAG and 

IMPROVE background visibility data, and below the threshold at all other sensitive areas. There 

were 11 days per year (FLAG) and 15 days per year (IMPROVE) when visibility impacts where 

predicted to be above the 1.0-dv threshold. The maximum dv change was estimated as 3.4 dv 

(FLAG) and 3.8 dv (IMPROVE). 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 19

Mid-field Impacts

Cumulative modeling results for the Preferred Alternative low emission scenario indicate 

impacts above the 1.0-dv threshold at all nearby Wyoming community locations. The highest 

frequency of predicted visibility impacts occurred at Big Sandy where they were 31 days 

(FLAG) and 32 days (IMPROVE) estimated to be above the 1.0-dv threshold. The maximum dv 

change, 3.7 dv (FLAG), and 4.2 dv (IMPROVE), was predicted to occur at Pinedale. 

In-field Impacts 

Direct impacts of NO2, SO2, PM10, and PM2.5 within the JIDPA resulting from Preferred 

Alternative low emissions scenario emissions and non-project regional emissions, when added to 

appropriate background concentrations, were predicted to be less than all applicable ambient air 

quality standards. 

2.3.3 Mitigation Scenarios

Far-field Impacts

Cumulative impacts resulting from the Preferred Alternative mitigation scenarios would be 

below all applicable ambient air quality standards and PSD increments. 

Cumulative impacts from all of the mitigation scenarios would result in an increase in ANC less 

than any LAC at all acid-sensitive lakes. Total S and N deposition impacts for any of the 

scenarios would not exceed the USDA Forest Service levels of concern. 

Cumulative visibility (regional haze) impacts for the 20 percent emissions reduction case were 

predicted to be above the 1.0-dv threshold at the Bridger, Fitzpatrick, and Popo Agie Wilderness 

Areas and the Wind River Roadless Area, and below the threshold at all other sensitive areas. 

The highest frequency of predicted visibility impacts occurred at the Bridger Wilderness where 

there were 25 days per year (FLAG) and 29 days per year (IMPROVE) when visibility impacts 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 20

where predicted to be above the 1.0-dv threshold, with the maximum dv change estimated as 5.4 

dv (FLAG) and 5.9 dv (IMPROVE). Cumulative visibility impacts for the 40 percent emissions 

reduction case were predicted to be above the 1.0-dv threshold at the Bridger and Popo Agie 

Wilderness Areas and the Wind River Roadless Area. The highest frequency of predicted 

visibility impacts occurred at the Bridger Wilderness where there were 16 days per year (FLAG) 

and 21 days per year (IMPROVE) when visibility impacts where predicted to be above the 1.0-

dv threshold, with the maximum dv change estimated as 4.4 dv (FLAG) and 4.8 dv (IMPROVE). 

Cumulative visibility impacts for the 60 percent emissions reduction case were predicted to be 

above the 1.0-dv threshold at the Bridger Wilderness Area and at the Wind River Roadless Area. 

The highest frequency of predicted visibility impacts occurred at the Bridger Wilderness where 

there were 11 days per year (FLAG) and 15 days per year (IMPROVE) when visibility impacts 

where predicted to be above the threshold, with the maximum dv change estimated as 3.3 dv 

(FLAG) and 3.6 dv (IMPROVE). Cumulative visibility impacts for the 80 percent emissions 

reduction case were predicted to be above the 1.0-dv threshold at the Bridger Wilderness using 

both the FLAG and IMPROVE background visibility data (5 and 6 days per year, respectively), 

with the maximum dv change estimated as 2.3 dv (FLAG) and 2.6 dv (IMPROVE). 

Mid-field Impacts

Cumulative modeling results for the Preferred Alternative 20 percent emissions reduction 

mitigation scenario indicated that visibility impacts were above the 1.0-dv threshold at all nearby 

Wyoming community locations with the highest frequency of predicted visibility impacts at Big 

Sandy (53 days per year – FLAG and 59 days per year – IMPROVE. The maximum dv change, 

6.6 dv (FLAG), and 7.4 dv (IMPROVE) was predicted to occur at Pinedale. The 40 percent 

emissions reduction case indicated cumulative impacts above the threshold at all areas with the 

maximum number of days per year at Big Sandy (35 days– FLAG, and 40 days – IMPROVE) 

and the maximum dv at Pinedale (5.3 dv – FLAG, 6.0 dv – IMPROVE). The 60 percent 

emissions reduction case also indicated cumulative impacts above the threshold at all areas with 

the maximum number of days per year at Big Sandy (27 days– FLAG, and 30 days – 

IMPROVE) and the maximum dv at Pinedale (3.9 dv – FLAG, 4.4 dv – IMPROVE). The 80 

percent emissions reduction scenario indicated cumulative impacts above the visibility threshold 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 21

at all areas except Bronx with the maximum number of days per year at Big Piney (8 days– 

FLAG, and 13 days – IMPROVE) and the maximum dv at Boulder (2.7 dv – FLAG, 3.1 dv – 

IMPROVE). 

In-field Impacts 

Cumulative impacts of NO2, SO2, PM10, and PM2.5 within the JIDPA resulting from Preferred 

Alternative mitigation scenarios, when added to appropriate background concentrations, were 

predicted to be less than all applicable ambient air quality standards. 

2.4 MITIGATION STRATEGIES 

In an effort to identify mitigation strategies to achieve reductions in emissions from the Preferred 

Alternative high emissions case, three field development parameters were assessed relative to 

their potential impact to visibility (regional haze) at the Bridger Wilderness Area. These 

parameters are: 1) WDR; 2) drill rig engine emissions levels (EPA Tier levels); and 3) number of 

active flares. The emissions inventory developed for this analysis was reviewed, and an example 

of how a change in any of these three variables could potentially result in emissions reductions 

and reduced visibility impacts at the Bridger Wilderness was compiled, as shown in Table 3. 

Analyses performed in the original AQTSD (TRC 2004) revealed drill rig engines as the primary 

emissions source affecting visibility; therefore, mitigation options focus on drill rigs. However, 

BLM’s authority to regulate flare numbers, drill rig emission rates, and/or WDRs has not been 

defined. Furthermore, the availability of drill rigs with Tier 2 emission levels is currently 

limited; therefore, transitional mitigation involving further reductions in WDRs and/or reduced 

flaring may be appropriate until more Tier 2 or other low emission drill rigs become available. 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 22

Table 3 Example Mitigation Options for the Jonah Infill Drilling Project 

Preferred Alternative 

 

Potential Project 

Emissions Reduction 

Wells Developed 

per year 1 Example Mitigation Options 

Potential Project Impact to 

Visibility in Bridger WA 

(days > 1 dv) 

50 100% of drill rigs with Tier 2 emissions 

levels, 1 completion flare 80% 

75 100% of drill rigs with Tier 2 emissions 

levels, 0 completion flares 

3 

250 100% of drill rigs with Tier 2 emissions 

levels, 1 completion flare 

200 

30% of drill rigs with Tier 1 emissions 

levels & 70% with Tier 2 emissions 

60% levels, 1 completion flare 

150 

20% of drill rigs with Tier 0 emissions 

levels, 20% with Tier 1 emissions levels 

& 60% with Tier 2 emissions levels, 1 

completion flare 

9 

250 

10% of drill rigs with Tier 0 emissions 

levels, 50% with Tier 1 emissions levels 

& 40% with Tier 2 emissions levels, 2 

completion flares 

250 

10% of drill rigs with Tier 0 emissions 

levels, 80% with Tier 1 emissions levels 

& 10% with Tier 2 emissions levels, 1 

completion flare 

40% 

200 

20% of drill rigs with Tier 0 emissions 

levels & 80% with Tier 1 emissions 

levels, 2 completion flares 

15 

250 

30% of drill rigs with Tier 0 emissions 

levels & 70% with Tier 1 emissions 

levels, 3 completion flares 

250 

40% of drill rigs with Tier 0 emissions 

levels & 60% with Tier 1 emissions 

levels, 2 completion flares 

250 

50% of drill rigs with Tier 0 emissions 

levels & 50% with Tier 1 emissions 

levels, 1 completion flare 

200 

70% of drill rigs with Tier 0 emissions 

levels & 30% with Tier 1 emissions 

levels, 3 completion flares 

20% 

200 

80% of drill rigs with Tier 0 emissions 

levels & 20% with Tier 1 emissions 

levels, 2 completion flares 

20 

0% 250 

80% of drill rigs with Tier 0 emissions 

levels & 20% with Tier 1 emissions 

levels, 3 completion flares 31 

1

 Assumes 50% of the wells are straight-hole drilled and 50% of wells directionally drilled.
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 23

3.0 EARLY-PROJECT-DEVELOPMENT STAGE MODELING 

An analysis of JIDP early-project-development stage air quality conditions in the vicinity of the 

JIDPA was performed. What has been modeled and presented in the DEIS for the Preferred 

Alternative and supplemented with additional model runs (described in Section 2.0) considers 

the “most likely case” maximum emissions scenario for the JIDP. However, when quantifying 

maximum cumulative impacts regionally, peak regional impacts appear to occur prior to JIDP 

maximum emissions as a result of the development of other natural gas projects in the region, 

specifically the Pinedale Anticline Project (PAP), South Piney Project (SPP), Riley Ridge 

Project (RRP), and Jack Morrow Hills Project (JMHP). The BLM performed this analysis 

because 1) regional impacts appear to be greatest during the early stages of JIDP development 

due to accelerated development paces in these nearby project areas, and 2) the emissions from 

increased drilling near Pinedale had not been adequately characterized in the DEIS. The Record 

of Decision (ROD) for the Pinedale Anticline EIS (BLM 1999) stated that if emissions of 

nitrogen oxides (NOx) from the Jonah and Pinedale Anticline gas fields reached 693.5 tons per 

year, the BLM would perform further air quality analyses. The analysis for the Questar Yearround drilling EA (BLM 2004), published after completion of the DEIS analysis, indicated that 

NOx emissions had substantially exceeded that level, due mainly to emissions from drill rigs. 

Drill rig emissions were higher than assumed in the PAPA EIS because: 

• there were more drill rigs operating than estimated; 

• conditions required drill rig engines to have larger horsepower than estimated; and 

• directional drilling required drill rigs to operate for a longer period of time per well than 

estimated. 

Unlike the Preferred Alternative modeling analyses (see Section 2.0), modeling analyses of the 

early-project-development stage emissions are not directly comparable to the results presented in 

the DEIS. 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 24

The goal of this analysis was to estimate an emissions scenario that could potentially occur 

within the next few years in the air basin located southwest of the Bridger Wilderness Area, as a 

result of 1) increased well drilling and flaring activities among several active natural gas field 

developments, and 2) expanded compression requirements, beyond what was analyzed for the 

DEIS (BLM 2005). To accomplish this goal a study base year, determined by available 

background pollutant data, was selected. Emissions estimates of well drilling and flaring were 

quantified for this baseline year for the JIDP, PAP, SPP, RRP, and JMHP. Emission estimates of 

well drilling, flaring, and expanded compression for these projects, and other companies 

operating within these project areas, which are representative of current year or early–projectdevelopment stage conditions, were then determined. Emission estimates for the baseline year 

were subtracted from the early-project stage emissions. This emissions “netting” determined the 

emissions changes from background to modeled conditions, and avoided “double-counting” 

existing background conditions in future air quality conditions. These emission changes were 

then modeled in combination with other JIDP sources and regional sources to estimate both 

project and cumulative pollutant impacts at far-field PSD Class I and sensitive Class II areas, at 

mid-field Wyoming regional community locations, and within the JIDPA. Other JIDP sources 

include expanded compression estimates, beyond what was analyzed for the DEIS, production 

and construction traffic emissions and wellsite heater emission representative of early project 

emissions, and wind erosion. Non-project regional emissions, with the exception of the PAP, 

SPP, RRP, and JMHP, included in the DEIS (BLM 2005) and as described in detail in the 

AQTSD (TRC 2004) were included in the modeling analyses. For the PAP, SPP, RRP and 

JMHP, the well drilling and flaring emissions differences were included along with any 

emissions that were included in the permitted source and RFD inventories for the DEIS analyses. 

The regional emissions include sources newly permitted by the state agencies through June 30, 

2003, reasonably foreseeable development (RFD), reasonably foreseeable future actions (RFFA), 

and Operator-projected compression estimates. These inventories were updated to include 

additional source emissions permitted through March 31, 2004, and these additional source 

emissions were included in the cumulative modeling analyses. 

The emissions information available for well drilling and flaring activities and expanded 

compression requirements, obtained prior to a cut-off date of May 26, 2005, were used in the 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 25

analysis. A study baseline year of 2002 was used because background visibility data through 

2002 was available. Year 2006 was selected as representative of a maximum emissions scenario 

for regional emissions. The 2006 inventory also included recent expanded compression 

estimates, in addition to the expanded compression estimates that were obtained prior to the 

DEIS analyses and included in the DEIS modeling. This analysis is described in detail in the

Jonah Infill Drilling Project Draft Air Quality Technical Support Document Supplement (TRC 

2005). The modeling analyses of the early-project-development stage emissions are not directly 

comparable to the results presented in Section 2.0 or in the DEIS due to differences (emissions 

increases) in the regional (non-project) emissions inventories and the expanded compression 

estimates included in this analysis. 

The CALMET and CALPUFF model versions that were used for the DEIS analysis were used to 

estimate direct JIDP and cumulative pollutant impacts at far-field PSD Class I and sensitive 

Class II areas, and at mid-field Wyoming regional community locations and within the JIDPA. 

Model results for the early-project-development stage modeling scenarios are summarized in the 

following sections. 

3.1 IMPACTS SUMMARY 

Tables 4 and 5 provide an overall summary of the maximum predicted impacts from the earlyproject-development stage modeling analyses. Table 4 provides a summary of the potential 

concentration and deposition impacts for both direct project and cumulative scenarios and Table 

5 provides a summary of the potential impacts to visibility (regional haze) for these scenarios. 

Results summaries shown in green (normal text) in these tables indicate that potential impacts 

are below ambient air quality standards, PSD increments, and BLM-defined significance 

threshold values and levels of concern. Results are compared to other agency-defined 

significance threshold values and levels of concern in the Jonah Infill Drilling Project Draft Air 

Quality Technical Support Document Supplement (TRC 2005). Results summaries shown in red 

(bold text) indicate that potential impacts are above these levels. The PSD demonstrations serve 

information purposes only and do not constitute a regulatory PSD Increment consumption 

analysis, which may be completed as necessary by WDEQ-AQD. The modeling analyses are not 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 26

directly comparable to the results presented earlier in Section 2.0 or in the DEIS due to 

differences in the regional emissions inventories and the expanded compression estimates 

included in this analysis. A complete disclosure of all modeled impacts for the early-projectdevelopment stage modeling analyses is provided in the Jonah Infill Drilling Project Draft Air 

Quality Technical Support Document Supplement (TRC 2005). A discussion of both the direct 

impacts and cumulative impacts are provided in the following sections. 

3.2 DIRECT PROJECT IMPACTS 

CALPUFF modeling was performed to calculate direct JIDP impacts for early-projectdevelopment stage conditions. Potential direct project far-field pollutant impacts were assessed 

at the PSD Class I areas and at the sensitive Class II Areas. Far-field analyses include impact 

assessments of concentration, visibility (regional haze), atmospheric deposition, and lake acidity. 

Mid-field visibility impact analyses were performed for the Wyoming regional community 

locations. In-field analyses include impact assessments of concentration within the JIDPA. 

Far-field Impacts

Direct impacts resulting from early-project-development stage source emissions would be below 

the applicable ambient air quality standards and PSD increments. PM10 concentrations exceed 

the proposed PSD Class I SILs at the Bridger Wilderness Area and at Grand Teton National Park 

and are below the SILs at all other sensitive areas. These SILs are proposed by EPA as an 

indicator of significance of New Source Review projects to determine additional analysis 

requirements. 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 27

Table 4 Early-Project-Development Stage Air Quality Concentrations and Deposition 

Impacts Summary 

Air Quality Component Criteria 

Source Group 

& Impact Area Early-Project-Development Stage 

Project: 

In-Field 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

 SO2 < NAAQS&WAAQS 

Cumulative: 

In-Field 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

 SO2 < NAAQS&WAAQS 

Project: 

Far-Field 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

Air Quality 

Standards 

Cumulative: 

Far-Field 

PM10 < NAAQS&WAAQS 

PM2.5 < NAAQS&WAAQS 

NO2 < NAAQS&WAAQS 

SO2 < NAAQS&WAAQS 

PSD Class I 

Increments 1

Cumulative: 

Far-Field 

PM10 < increment 

NO2 < increment 

SO2 < increment

Concentrations 

PSD Class II 

Increments 1

Cumulative: 

Far-Field 

PM10 < increment 

NO2 < increment 

SO2 < increment 

N Deposition Total: 

Far-Field N < LOC, All Areas 

S Deposition Total: 

Far-Field S < LOC, All Areas 

Project: 

Far-Field ANC Change < LAC, All Lakes 

Atmospheric Deposition 

Sensitive 

Lakes Cumulative: 

Far-Field ANC Change < LAC, All Lakes

1 The PSD demonstrations serve information purposes only and do not constitute a regulatory 

 PSD Increment consumption analysis.
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 28

Table 5 Early-Project-Development Stage Visibility (Regional Haze) Impacts Summary 

Air Quality Component Impact Area Source Group Early-Project-Development Stage 

Project 

Bridger WA, >1.0-dv 9 days, max dv = 2.42 

Fitzpatrick WA, >1.0-dv 0 days, max dv = 0.95 

Popo Agie WA, >1.0-dv 2 days, max dv = 1.06 

Wind River RA, >1.0-dv 1 days, max dv = 1.01 

Grand Teton NP, >1.0-dv 0 days, max dv = 0.67 

Teton WA, >1.0-dv 0 days, max dv = 0.37 

Yellowstone NP, >1.0-dv 0 days, max dv = 0.32 

Washakie WA, >1.0-dv 0 days, max dv = 0.43

PSD Class I and 

Sensitive Class 

II Areas 

 

Cumulative 

Bridger WA, >1.0-dv 61 days, max dv = 6.57 

Fitzpatrick WA, >1.0-dv 11 days, max dv = 3.37 

Popo Agie WA, >1.0-dv 23 days, max dv = 3.35 

Wind River RA, >1.0-dv 15 days, max dv = 3.39 

Grand Teton NP, >1.0-dv 8 days, max dv = 2.63 

Teton WA, >1.0-dv 4 days, max dv = 1.33 

Yellowstone NP, >1.0-dv 3 days, max dv = 1.22 

Washakie WA, >1.0-dv 2 days, max dv = 1.70 

Project 

Big Piney, >1.0-dv 24 days, max dv = 6.62 

Big Sandy, >1.0-dv 24 days, max dv = 3.66 

Boulder, >1.0-dv 18 days, max dv = 3.37 

Bronx, >1.0-dv 8 days, max dv = 1.79 

Cora, >1.0-dv 11 days, max dv = 2.17 

Daniel, >1.0-dv 14 days, max dv = 2.93 

Farson, >1.0-dv 33 days, max dv = 5.18 

Labarge, >1.0-dv 11 days, max dv = 5.73 

Merna, >1.0-dv 7 days, max dv = 2.46 

Pinedale, >1.0-dv 14 days, max dv = 2.94 

Visibility 

(Regional Haze) 

Wyoming 

Regional 

Communities 

Cumulative 

Big Piney, >1.0-dv 85 days, max dv = 14.43 

Big Sandy, >1.0-dv 108 days, max dv = 8.42 

Boulder, >1.0-dv 131 days, max dv = 10.59 

Bronx, >1.0-dv 63 days, max dv = 9.60 

Cora, >1.0-dv 73 days, max dv = 9.95 

Daniel, >1.0-dv 88 days, max dv = 12.68 

Farson, >1.0-dv 77 days, max dv = 10.85 

Labarge, >1.0-dv 39 days, max dv = 11.12 

Merna, >1.0-dv 33 days, max dv = 6.25 

Pinedale, >1.0-dv 113 days, max dv = 10.32 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 29

Direct project source emissions from the early-project-development stage would not result in an 

increase in ANC above any LAC at the acid-sensitive lakes. The predicted maximum S 

deposition impacts are below the DAT at all sensitive PSD Class I and Class II areas. The 

maximum N impacts were predicted to be above the 0.005 kg/ha-yr threshold at the Bridger and 

Popo Agie Wilderness Areas and below the DAT at all other sensitive areas. The maximum 

predicted N deposition impacts are 0.014, and 0.009 kg/ha-yr at the Bridger and Popo Agie 

Wilderness Areas, respectively. The exceedances of this threshold trigger a management 

concern but are not necessarily indicative of an adverse impact (NPS 2004). 

Direct visibility (regional haze) impacts were predicted to be above the "just noticeable visibility 

change" (1.0-dv) threshold at the Bridger and Popo Agie Wilderness Areas, and at the Wind 

River Roadless Area, and below the threshold at all other sensitive areas. The highest frequency 

of predicted visibility impacts occurred at the Bridger Wilderness where there were 8 days per 

year (FLAG) and 9 days per year (IMPROVE) when visibility impacts where predicted to be 

above the 1.0-dv threshold. The maximum dv change was estimated as 2.2 dv (FLAG) and 2.4 

dv (IMPROVE). 

Mid-field Impacts

Modeling results for the early-project-development stage indicate impacts above the 1.0-dv 

threshold at all nearby Wyoming community locations. The highest frequency of predicted 

visibility impacts occurred at Farson where they were 31 days (FLAG) and 33 days (IMPROVE) 

estimated to be above the 1.0-dv threshold. The maximum dv change, 5.9 dv (FLAG), and 6.6 

dv (IMPROVE) was predicted to occur at Big Piney. 

In-field Impacts 

Direct impacts of NO2, SO2, PM10, and PM2.5 within the JIDPA resulting from early-projectdevelopment stage conditions emissions, when added to appropriate background concentrations, 

were predicted to be less than all applicable ambient air quality standards. 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 30

3.3 CUMULATIVE IMPACTS 

CALPUFF modeling was performed to calculate cumulative impacts from potential project and 

regional sources. Regional emissions inventories of existing state-permitted, RFD, and RFFA 

sources were modeled in combination with project sources to provide cumulative impact 

estimates. Cumulative far-field pollutant impacts were assessed at the PSD Class I areas and at 

the sensitive Class II Areas. Far-field analyses include impact assessments of concentration, 

visibility (regional haze), atmospheric deposition, and lake acidity. Mid-field visibility impact 

analyses were performed for the Wyoming regional community locations. In-field analyses 

include impact assessments of concentration within the JIDPA. 

Far-field Impacts

Cumulative impacts resulting from early-project-development stage conditions source emissions 

would be below all applicable ambient air quality standards and PSD increments. 

 

Cumulative project and non-project source emissions resulting from early-project-development 

stage conditions would not result in an increase in ANC above any LAC at the acid-sensitive 

lakes. Total S and N deposition impacts would not exceed the USDA Forest Service levels of 

concern (5 kg/ha-yr for S and 3 kg/ha-yr for N), for comparison of potential impacts from 

cumulative source emissions. It is understood that the USDA Forest Service no longer considers 

these levels of concern to be protective; however, in the absence of alternative FLM-approved 

values, comparisons with these values were made. 

Cumulative visibility (regional haze) impacts were predicted to be above the 1.0-dv threshold at 

the Bridger, Fitzpatrick, Popo Agie, Teton, and Waskakie Wilderness Areas, at Grand Teton and 

Yellowstone National Parks, and at the Wind River Roadless Area using both the FLAG and 

IMPROVE background visibility data. The highest frequency of predicted visibility impacts 

occurred at the Bridger Wilderness where there were 61 days per year (FLAG) and 59 days per 

year (IMPROVE) when visibility impacts where predicted to be above the 1.0-dv threshold. The 

maximum dv change was estimated as 6.0 dv (FLAG) and 6.6 dv (IMPROVE). 
Draft EIS Air Quality Impact Analysis Supplement, Jonah Infill Drilling Project 31

Mid-field Impacts

Cumulative modeling results for the early-project-development stage indicate impacts above the 

1.0-dv threshold at all nearby Wyoming community locations. The highest frequency of 

predicted visibility impacts occurred at Boulder where they were 131 days (FLAG) and 130 days 

(IMPROVE) estimated to be above the 1.0-dv threshold. The maximum dv change, 13.3 dv 

(FLAG), and 14.4 dv (IMPROVE) was predicted to occur at Big Piney. 

In-field Impacts 

Cumulative impacts of NO2, SO2, PM10, and PM2.5 within the JIDPA resulting from earlyproject-development stage emissions and non-project emissions, when added to appropriate 

background concentrations, were predicted to be less than all applicable ambient air quality 

standards. 
Draft EIS Air Quality Analysis Supplement, Jonah Infill Drilling Project 

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