August 27, 2009 Installation Date Profile Update-Revised 1

Task Order No. 3003—Task 2, Subtask e

TDD #18—New UST Installations

Installation Date Profile Update Revised 8/27/09

E2 Inc. assisted EPA’s Office of Underground Storage Tanks (OUST) by compiling and updating 

information on new UST installations in the United States (U.S.) for 2002-2008. This work expands on 

the analysis conducted under TDD #25 of TO 1010-A1 (New UST Installations). Sixteen state and eight 

regional (Indian Lands) databases were used to extract information on the number of new UST 

installations for calendar years 2007 and 2008 and updates were made to the data previously extracted for 

calendar years 2002-2006.1For state data, data from the years 2002 on for which the state had the full 

year of information were extracted (see accompanying Appendix for state database timestamps); all the 

data available for the years 2002 through 2008 were extracted from the Indian Lands databases. The 

information for Indian Lands installations may be slightly under counted for 2008, because the tribal 

databases only contain data through September 2008.

E2 Inc. filtered each database to include only federally regulated USTs. Some states indicated whether 

tanks were federally regulated by stating this on their Web sites or containing a column within their 

databases to specify this (see Appendix). For states that did not indicate federally regulated tanks, E2 Inc. 

employed a filtering process removing: aboveground storage tanks; tanks with capacities of 110 gallons

or less; tanks storing heating oil for consumptive use on the premises; and farm or residential tanks 

storing 1,100 gallons or less of motor fuel. For some states, the above criteria were easily identifiable 

from the data fields (e.g., there was a data field for tank type specifying “farm” for a 1,000 gallon tank); 

for other states, E2 Inc. used its best professional judgment to eliminate tanks that met these criteria (e.g., 

there was no data field for tank type specifying “farm” for a 1,000 gallon tank, but the owner was named 

“Maple Valley Farm”). This analysis includes currently in use, temporarily closed, and permanently 

closed USTs. For the most part, none or only a few tanks per database per year were removed via the 

filtering process.

After filtering, the number of tanks installed in each year was summed and recorded in the spreadsheet 

accompanying this report. When data were available, for each year, the number of new tanks only that 

were secondarily contained (with no secondary containment on the piping system), the number of new 

tanks with piping systems that were secondarily contained (with no secondary containment on the tank), 

and the number of new tanks and piping systems that were both secondarily contained were counted. 

When secondary containment was indicated for a given tank and piping system and interstitial monitoring 

information was available, interstitial monitoring use was determined. Interstitial monitoring was counted 

for tanks when tanks only had secondary containment; for pipes when pipes only had secondary 

containment; and for both the tank and pipes when both the tank and pipes had secondary containment.

Interstitial monitoring was not counted when both the tank and pipes had secondary containment, but only 

the tank or piping system had interstitial monitoring. Overall, secondary containment and interstitial 

monitoring data were available for about half of the 24 databases used in this analysis. The following 

types of tanks were considered secondarily contained: double walled, totally contained, jacketed, those 

with internal or external liners, and those with vaults; all double walled pipes were considered secondarily 

contained. For those databases that included different installation dates for tanks and piping, only the tank 

installation date was used. For a few databases, information was only available for the UST (Missouri, 

Ohio, and South Dakota), but not the pipes. These data were recorded in the “On UST but not on Piping” 

column of the spreadsheet. For each year, the numbers of tanks were summed across databases (Table 1). 

 

1 Exceptions are Alabama and Tennessee. No updates were made for Alabama because no database was available 

for Alabama. No updates were made for Tennessee because the database was the same as that used for TO 1010-

A1.
August 27, 2009 Installation Date Profile Update-Revised 2

Table 1: Number and Percentage of Actual New Installations with Secondary Containment and 

Interstitial Monitoring for 24 State and Regional Databases

Year

Total 

# New 

USTs

On UST but not Piping On Piping but not UST On both UST & Piping

Sec Cont Interstitial Mon Sec Cont Interstitial Mon Sec Cont Interstitial Mon

# % # % # % # % # % # %

2002 3,806 265 16 47 6 160 15 144 15 491 45 170 22

2003 3,034 270 18 52 7 128 14 92 13 408 44 200 28

2004 2,669 261 18 97 12 133 15 65 8 482 56 259 33

2005 2,664 281 22 103 19 44 7 42 7 424 67 211 39

2006 2,925 430 34 99 19 45 8 27 5 350 60 179 34

2007 2,680 300 29 77 16 55 10 47 10 384 67 169 35

2008 2,493 237 28 73 18 35 7 26 7 368 78 182 46

The data extracted from the 24 available databases were used to estimate the total number of new 

installations in the entire U.S. during 2002 through 2008 and the numbers of these new installations with 

secondary containment and interstitial monitoring.

2

Percentages for secondary containment and interstitial 

monitoring are based on the numbers of new tanks and piping installed. These values are dependent on 

the numbers reported in state databases and whether a state tracked secondary containment information 

for tanks, piping, both, or neither. The annual number of new installations in the U.S. was calculated by 

multiplying the number of total active tanks in the U.S. by the ratio of new tanks to active tanks in the 

sample according to the equation:3

New USTsTotal = Active USTsTotal * (New USTsSample/ Active USTsSample)

Similarly, for each year, the total numbers of active tanks in each category of secondary containment and 

interstitial monitoring were calculated by multiplying the number of new installations in each category by 

the ratio of the total active USTs to the number of active tanks in each category according to the equation:

Active USTsIMorSCTotal = New USTsIMorSCSample * (Active USTsTotal / Active USTsSample)

The extrapolation results are show in Table 2 below.

Table 2: Extrapolated Total Numbers of Active Tanks in the United States with Secondary Containment 

and Interstitial Monitoring

Year

Number of 

Active 

Tanks*

Number of 

New 

Tanks

On UST but not Piping On Piping but not UST On both UST & Piping

Sec Cont Interstitial 

Mon

Sec Cont Interstitial 

Mon

Sec Cont Interstitial 

Mon

2002 697,966 12,270 1,441 505 1,284 1,206 3,941 1,828

2003 682,870 9,870 1,496 564 1,030 999 3,283 2,171

2004 672,297 8,623 1,700 1,056 1,367 708 4,953 2,820

2005 653,621 8,528 2,146 1,510 596 569 5,741 3,093

2006 641,881 9.197 3,264 1,446 606 394 4,713 2,615

2007 629,866 8,425 2,271 1,121 738 684 5,155 2,461

2008 623,319 7,833 1,793 1,081 476 385 5,003 2,696

*The values in this column are the only actual values in the table. The rest were extrapolated.

 

2 The number of states and tribal regions for which data in each category were available varied slightly by year.

3

For each year, the total number of active USTs in the U.S. was acquired from second half fiscal year reports at 

http://www.epa.gov/oust/cat/camarchv.htm.