MEMORANDUM 

TO: Airport Deicing Administrative Record 

FROM: Mark Briggs and Mary Willett, ERG

DATE: October 2010

SUBJECT: Estimated Land Requirements and Opportunity Costs for the Anaerobic 

Fluid Bed Treatment System and ADF Stormwater Storage Tanks 

EPA agrees with comments provided on the proposed airport deicing rule that the opportunity 

cost of land use for treatment and storage should be included in the overall costs. This 

memorandum estimates the land required for both the anaerobic fluid bed (AFB) treatment 

system and for storage tanks that store ADF contaminated stormwater. EPA also evaluated what 

opportunity cost to assess with the land requirements for use in the costing model. 

Costing Approach 

EPA’s approach to estimating the cost for land is to first estimate the amount of land needed for 

the AFB and storage tanks, and then apply an opportunity cost per square foot. The opportunity 

cost assumes the land could potentially be leased for some other use by an airport tenant if not 

being used for the treatment and storage system. Another alternative for evaluating the 

opportunity cost of the land is if the land were purchased and that cost were amortized over time 

to assess its value. 

Land Requirements for AFB and Storage

To estimate the area of land associated with the AFB treatment system, ERG obtained 

information on the footprint of the AFB systems at Albany and Akron. According to Albany, 

their AFB treatment system occupies less than 3,500 square feet (sq.ft.)1

. Examining the space 

proposed for the AFB treatment at Akron indicates this system would occupy approximately 

5,200 sq.ft.2

 Unfortunately, neither of these data sources provides sufficient information to 

determine if this space included the AFB reactors and any associated buildings and ancillary 

equipment. Therefore, to obtain a better estimate of the footprint needed for a complete AFB 

treatment system, ERG used GoogleEarth and examined the entire treatment system area at 

Albany. Based on a review of the GoogleEarth images, ERG estimates a more appropriate 

footprint for the AFB treatment system is approximately 2.4 acres or 104,544 sq.ft. This area 

would include the reactors, associated buildings, pump houses, roadways and parking areas, etc. 

The GoogleEarth image used to estimate the size of the complete AFB treatment system is 

provided at the end of this memorandum. Since most AFB systems are expected to have similar 

land requirements, regardless of the daily COD loading and individual reactor size, EPA will 

assume all airports that install an AFB treatment system will require 104,544 sq.ft. of land. 

 

1

 Bascom, R., Sober, M., Owens, R., Anaerobic Treatment of Deicing Wastewater at Albany International Airport – 

A Case Study. 14th Annual Aircraft and Airfield Deicing Stormwater Conference, August 2005. 2

 McQueen, R., and Arendt, T., Development of a Deicer System for Akron-Canton Airport 
Memorandum 

October 2010 

Page 2 

To predict the amount of land needed for storage tanks, ERG used the following equation 

developed for predicting storage tank costs: 

Storage Tank Size (gal) = ADF Use gal/yr × 13.1 gal/gal/yr 

Combining this equation with the equation developed from Figure 1 allows EPA to estimate the 

minimum footprint for storage tanks at individual airports based on ADF use. The equation 

shown in Figure 1 is based on storage tanks with a 14 foot sidewall3

 depth. 

Tank Area Versus Volume

y = 0.0095x - 7E-12

R2

 = 1

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

0 2,000,000 4,000,000 6,000,000 8,000,000 10,000,000

Volume (gal)

Area (ft2)

Figure 1. Footprint for Various Sizes of Circular Storage Tanks 

Minimum Storage Tank Footprint (sq.ft.): (ADF Use gal/yr × 13.1 gal/gal/yr × 0.0095 ft2/gal) 

Since storage tanks require a barrier free area of approximately 20 feet around the entire tank for 

maintenance, along with access roads to the tanks, ERG decided to increase the minimum tank 

footprint by 20 percent. 

Actual Storage Tank Footprint (sq.ft.): 1.2 × (ADF Use gal/yr × 13.1 gal/gal/yr × 0.0095 ft2/gal) 

The following example shows how the equation above can be used to predict a storage tank 

footprint for an airport that applies 400,000 gallons per year of ADF. 

Example Storage Tank Footprint: 

Storage Tank Footprint (sq.ft.): 1.2 × (400,000 gal/yr × 13.1 gal/gal/yr × 0.0095 ft2/gal) = 

59,736 sq.ft. (or about 1.4 acres) 

 

3

 Fulhage, C.D., and Pfost, D., Storage Tanks for Liquid Livestock Manure. University of Missouri Extension, EQ 

389. 
Memorandum 

October 2010 

Page 3 

Opportunity Cost of Airport Land

EPA believes that siting of AFB and deicing stormwater storage systems will require their 

placement away from the terminal and main runway area. In assessing the opportunity costs for 

that property, EPA considered lease/fee costs and land purchase costs. Table 1 shows the 

information that ERG identified from publicly available financial reports for various airports 

related to types of leasing costs or fees for property that is away from the main terminal area: 

Table 1. Leasing/Fee Cost Information by Airport 

Airport Hub Size Lease Type Leasing Costs ($/sq.ft.) 

Albany Small Apron Fee $1.02/sq.ft. in 2004 

Indianapolis Medium Apron Fee $2.62 sq.ft. in 2010 

Bismarck, ND Non-Hub Land Lease $0.2 - $0.4/sq.ft. in 2009 

Shreveport, LA Cargo Apron Fee $0.75/sw.ft. in 2009 

Lot Rental $0.18 - $0.48/sq.ft. in 2009 

ERG also looked at land purchase costs for Chicago O’Hare Airport’s improvement program. 

As part of this program, the airport purchased 433 acres for $283 million (about $653,000/acre). 

This amount amortized over 30 years using an assumed 7 percent real rate and converted to an 

annualized cost per square foot results in $1.21/sq.ft. The actual nominal interest rate for land 

acquisition is believed to be closer to 4 percent which would result in an amortized cost of 

$0.87/sq.ft. 

Based on these potential opportunity costs, EPA selected an estimated $1.00/sq.ft. cost for 

purposes of the costing model. 

Summary

The equations included in this memorandum will be used in the airport deicing costs model to 

estimate the amount of land needed for storage tanks and an AFB treatment system. For AFB 

treatment systems, approximately 104,544 sq.ft. of land will be required. For storage tanks, land 

requirements will be predicted based on annual ADF use. For both the AFB treatment systems 

and storage tanks, land opportunity costs will be estimated by multiplying the land requirement 

(sq.ft.) by an opportunity cost for the land of $1.00/sq.ft to estimate the annual cost for land use. 
Memorandum 

October 2010 

Page 4 

GoogleEarth Image for Albany Airport AFB System