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State Gas Pipelines Natural Gas as an Expanding

Making State Gas Pipelines Safe and Reliable: An Assessment of State Policy

Outline

NCSL Staff Contact

Kristy Hartman

March 2011 
By Jacquelyn Pless

Natural Gas as an Expanding Industry

Two-thirds of the lower 48 states depend almost entirely on interstate pipeline systems for natural gas supplies.8,9  Figure 1 illustrates this intricate network.

Figure 1. Natural Gas Pipeline Network—Lower 48 States (2009)

Natural Gas Pipeline Network - Lower 48 States

 
 
 
 
 
 
 
 
 
 
 
Interstate

About 71 percent of all U.S. natural gas transmission is made up of interstate natural gas pipeline. In Figure 2, the 31 states in grey obtain at least 85 percent of their natural gas from the interstate network.

Figure 2. Interstate Natural Gas Supply Dependency (2007)
 

 Map of Interstate Natural Gas Supply Dependency

 

 

 

 

 

 

 

 

 

 

 

 

 

Notes: EIA determines state’s relative dependence on the interstate natural gas pipeline network for suppliers by calculating the level of natural gas consumed within the State (2007) relative to the amount of natural gas produced within the state. If no natural gas is produced within the state, it is 100 percent dependent on the interstate network.
Source: U.S. Energy Information Administration, Form EIA176 “Annual Report of Natural Gas and Supplemental Gas Supply and Disposition,” About U.S. Natural Gas Pipelines, Transporting Natural Gas; http://www.eia.doe.gov/pub/oil_gas/natural_gas/analysis_publications/ngpipeline/dependstates_map.html.
 

Intrastate

 In the lower 48 states, more than 90 intrastate natural gas pipelines link producers to local markets and the interstate pipeline network. As the top natural gas consuming state, Texas’ intrastate pipelines account for 45,000 miles of its 58,000 miles of natural gas pipelines. California, ranked second for natural gas consumption, is dominated by only a few distribution companies, including Southern California Gas (SoCal) and California Gas Transmission Company (PG&E)—two of the nation’s largest distribution companies.

Variation of Incidents Despite Similar Inspection Efforts

All states except Alaska and Hawaii conduct natural gas pipeline inspections and report efforts as Inspection Person Days, the number of days spent in the field conducting inspections. Data reveal that, in 2009, Inspection Person Days varied from 62 in Maine to 4,368 in New York with a median of 499.10

Pipeline mileage varies substantially across states, however, and Inspection Person Days per mile of pipeline may be a more accurate reflection of inspection activity since it indicates how much time states spend inspecting comparable lengths of pipeline. Inspection Person Days per 1,000 Miles of Natural Gas Transmission Pipeline ranges from 26 in Montana to 1,305 in Rhode Island, a 50-fold difference, with a median of 107. To access this data, visit the chart below.  Alaska and Hawaii are omitted since the Office of Pipeline Safety (OPS) regulates, enforces and inspects all activity there, and the District of Columbia is not included.

NCSL’s analysis reveals that states that dedicate less time to inspections generally experience more significant incidents, which suggests that more inspection time results in less incidents. On average, states with less than 400 inspection person days a year experienced 1.55 significant accidents per 1,000 miles of pipeline, whereas states with more than 400 inspection person days experienced an average of 0.9 significant incidents, a 41 percent decrease. When an outlier state is omitted from the analysis, the decline is even more substantial—resulting in a seventy five percent decrease.

However, some states experience more incidents than those that devote similar amounts of time for inspections. For example, the 22 states dedicating less than 100 inspection person days a year experienced between 0.41 and 4.60 significant incidents per 1,000 miles of pipeline. Regulators in some states may want to consider ensuring proper inspection practices, possibly through more stringent rules and regulations rather than by allotting more time to inspection.

A graph illustrating the relationship between Inspection Person Days per 1,000 Miles of Natural Gas Pipeline and Gas Transmission Significant Accidents per 1,000 Miles of Gas Transmission Pipeline can be found below


  Population Density and Pipeline Mileage per Square Foot of Land

Data reveal substantial variation among the number of significant incidents involving all gas pipelines when compared to population density and pipeline mileage per square foot of land (pipeline density). A positive relationship exists, however, between significant incidents and natural gas transmission pipeline density, which indicates that states with higher pipeline density may require more stringent oversight. This relationship does not hold for population density.

To access this dataset, please see the chart detailing natural gas transmission pipeline mileage and incidents below. 

A graph illustrating the relationship between incidents and pipeline density can be found here.

 

Natural Gas Pipeline Inspection (2009)

STATE

Natural Gas Inspection Person Days1

Inspection Person Days per 1,000 Miles of Gas Transmission Pipeline

Significant Accidents per 1,000 Miles of Gas Transmission Pipeline2

Alabama

1128

161.7

1.58

Arizona

1266

194.6

1.23

Arkansas

645

85.5

2.12

California

787

65.9

1.84

Colorado

395.4

48.9

1.11

Connecticut

342

585.6

0.00

Delaware

87

289.0

0.00

Florida

996

204.5

2.05

Georgia

1009

228.1

1.36

Idaho

135

88.8

4.60

Illinois

928.5

97.8

1.58

Indiana

771.5

144.7

1.88

Iowa

404.8

48.7

0.84

Kansas

850

58.9

2.01

Kentucky

463

62.9

1.63

Louisiana

1358

45.1

3.36

Maine

62

144.2

0.00

Maryland

495.7

516.4

5.21

Massachusetts

844.5

764.3

0.00

Michigan

502

56.0

1.34

Minnesota

596.01

107.7

1.26

Mississippi

553.5

50.7

2.20

Missouri

584

124.3

1.92

Montana

99

25.7

0.52

Nebraska

382

65.6

1.20

Nevada

802

477.9

1.19

New Hampshire

171.5

708.7

0.00

New Jersey

398

273.0

2.74

New Mexico

535

81.9

0.77

New York

4368

960.4

0.88

North Carolina

473

120.7

1.02

North Dakota

94

43.7

0.46

Ohio

1630

159.3

1.08

Oklahoma

1030

78.5

1.37

Oregon

372

155.4

0.42

Pennsylvania

1041

104.3

2.71

Rhode Island

124

1305.3

0.00

South Carolina

319

120.7

0.38

South Dakota

116.5

71.7

1.23

Tennessee

445

90.8

0.41

Texas

2768

50.4

2.04

Utah

270

74.9

0.83

Vermont

92

1295.8

0.00

Virginia

1542.1

522.6

1.02

Washington

636.14

329.4

3.63

West Virginia

420

106.2

3.03

Wisconsin

434

96.3

1.33

Wyoming

177.33

27.2

1.54

Median

498.85

106.9

1.2

Source: Inspection Person Days provided by PHMSA - obtained from 2010 certification

documents reporting activity for 2009;

Notes: 1) Inspection person days represent the number of days spent in the field conducting inspections. Some states such as Virginia may have included inspection person days for enforcing Damage Prevention Laws

2) PHMSA Pipeline Safety Program and author's calculations

Figure 3:  Gas Transmissions

 

 

 

 

 

 

 

 

 

 

 

 

 

Natural Gas Transmission Pipeline Mileage and Incidents

STATE

Natural Gas Transmission (NGT) Pipeline Mileage (2010)1

NGT mileage per square foot of land2

Population per square mile of land3

Population density (population per sq. mile) per mile of NGT pipeline

Gas Transmission Significant Incidents (2000-2009)

Alabama

6,976

0.137

92.79

0.013

11

Arizona

6,507

0.057

58.04

0.009

8

Arkansas

7,543

0.145

55.49

0.007

16

California

11,940

0.077

237.00

0.020

22

Colorado

8,090

0.078

48.45

0.006

9

Connecticut

584

0.121

726.20

1.243

0

Delaware

301

0.154

453.08

1.505

0

Florida

4,871

0.090

343.76

0.071

10

Georgia

4,424

0.076

169.74

0.038

6

Idaho

1,521

0.018

18.68

0.012

7

Illinois

9,497

0.171

232.27

0.024

15

Indiana

5,333

0.149

179.08

0.034

10

Iowa

8,308

0.149

53.84

0.006

7

Kansas

14,424

0.176

34.45

0.002

29

Kentucky

7,366

0.185

108.59

0.015

12

Louisiana

30,093

0.691

103.12

0.003

101

Maine

430

0.014

42.72

0.099

0

Maryland

960

0.098

583.14

0.607

5

Massachusetts

1,105

0.141

841.02

0.761

0

Michigan

8,970

0.158

175.51

0.020

12

Minnesota

5,535

0.070

66.15

0.012

7

Mississippi

10,911

0.233

62.93

0.006

24

Missouri

4,697

0.068

86.92

0.019

9

Montana

3,856

0.026

6.70

0.002

2

Nebraska

5,826

0.076

23.37

0.004

7

Nevada

1,678

0.015

24.07

0.014

2

New Hampshire

242

0.027

147.70

0.610

0

New Jersey

1,458

0.197

1,173.97

0.805

4

New Mexico

6,534

0.054

16.56

0.003

5

New York

4,548

0.096

413.89

0.091

4

North Carolina

3,919

0.080

192.58

0.049

4

North Dakota

2,152

0.031

9.38

0.004

1

Ohio

10,232

0.250

281.88

0.028

11

Oklahoma

13,124

0.191

53.69

0.004

18

Oregon

2,394

0.025

39.85

0.017

1

Pennsylvania

9,980

0.223

281.25

0.028

27

Rhode Island

95

0.091

1,007.92

10.610

0

South Carolina

2,644

0.088

151.49

0.057

1

South Dakota

1,625

0.021

10.71

0.007

2

Tennessee

4,901

0.119

152.76

0.031

2

Texas

54,933

0.210

94.66

0.002

112

Utah

3,605

0.044

33.90

0.009

3

Vermont

71

0.008

67.22

0.947

0

Virginia

2,951

0.075

199.09

0.067

3

Washington

1,931

0.029

100.15

0.052

7

West Virginia

3,955

0.164

75.58

0.019

12

Wisconsin

4,507

0.083

104.12

0.023

6

Wyoming

6,510

0.067

5.61

0.001

10

Median

4,623

0.089

97.40

0.019

7

 

 

 

 

 

 

Source: PHMSA Pipeline Safety Program, US Census Bureau, and author's calculations, 2010.

Notes:

 1) Office of Pipeline Safety, PHMSA Pipeline Safety Program (Washington, D.C.: U.S. Department of Transportation, n.d.); http://primis.phmsa.dot.gov/comm/.

2) Author's calculations from most current land area estimates extracted from U.S. Census Bureau (2000), 2010.

3) Author's calculations from most current population estimates (July 2009) extracted from U.S. Census Bureau, 2010.

 

Transmission pipeline mileage per square foot of land vs. gas transmission significant incidents

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

7 Northwest Gas Association, Natural Gas Supply Serving the Pacific Northwest 5, no. 2 (West Linn, Ore.: NWGA, n.d.)

8 U.S. Energy Information Administration, About U.S. Natural Gas Pipelines (Washington, D.C.: EIA, n.d.); http://www.eia.doe.gov/pub/oil_gas/natural_gas/analysis_publications/ngpipeline/index.html.

9 U.S. Energy Information Administration, About U.S. Natural Gas Pipelines, Interstate Natural Gas Pipeline Segment, (Washington, D.C.: EIA, n.d.); http://www.eia.doe.gov/pub/oil_gas/natural_gas/analysis_publications/ngpipeline/interstate.html.

10Author’s calculations with data gathered by PHMSA from 2010 certification documents reporting activity for 12 months ending Dec. 31, 2009.

 March 2011

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