### MEMORANDUM

TO: Airport Deicing Administrative Record

FROM: Mark Briggs and Mary Willett, ERG

DATE: October 2010

SUBJECT: Estimated Capital and Operating Costs for Storage Tanks

This memorandum estimates both the capital and annual operating and maintenance (O&M) costs for an airport to install storage tanks for stormwater impacted by ai rcraft deicing and antiicing fluid (ADF). Costs have been developed for tanks that are used to store ADF impacted stormwater prior to discharging to a Publicly Owned Treatment Plant (POT W) or to an on-site treatment system. The tank costs described in the following paragraphs have taken into
consideration comments received on the proposed rule. First, EPA agrees with the comment that normalizing tank volume to the number of airline de partures as was done at proposal is not the preferred method of calculating th e necessary tank volume. Theref ore, EPA has normalized tank storage volume requirements to annual ADF use. EPA believes ADF use will account for
variables such as dilution caused by variable size storm events in different regions of the United States. Next, EPA agrees with the comment that all data should be used to estimate tank volume requirements and associated costs, and theref ore tank volumes for both Akron and Denver are included in the analysis. By including all tanks designed to contain the va riety of precipitation events occurring at a particular airport during the course of a deici ng season, the likelihood of underestimating tank size and ultimately tank costs have been reduced. Lastly, EPA agrees with

the comment that all tanks considered for th is analysis should be above-ground permanent storage tanks, and therefore the following anal ysis does not include e ither underground storage tanks or temporary “frac” tanks.

Costing Approach

Storage tanks are used at airpor ts to provide either flow and/ or concentration equalization of aircraft deicing and anti-icing fluid (ADF) contam inated stormwater prior to POTW discharge or to an on-site treatment system. The actual size of the storag e tanks depends primarily on the amount of ADF impacted stormwater generated during precipitation events, the area from which deicing stormwater is collected, a nd the rate the tanks can be disc harged to either the POTW or the on-site treatment system.

For EPA’s airport deicing operations effluent guidelines program, ERG obtained storage tank volumes from five airports: Denver 1 , Cincinnati 2 , Pittsburgh 3 , Portland 4 and Akron 5 . ERG was also able to obtained installed capital costs fo r the storage tanks at Denver, Cincinnati and

1 USEPA Engineering Site Visit Report for Denver International Airport, August 2006.

2 USEPA Engineering Site Visit Report for Cincinnati/Nor thern Kentucky International Airport, Sept. 2007.

3 USEPA Engineering Site Visit Report for P ittsburgh International Airport, August 2006.

4 USEPA Engineering Site Visit Report for Portland , Oregon International Airport, August 2006.

5 McQueen, R., and Arendt, T., Development of a Deicer System for Akron-Canton Airport.Memorandum
October 2010 Page 2

Akron. Using normalized ADF usage data for ea ch of these airports, ERG normalized tank volumes and costs to the annual ADF use per year to provide an equation that could be used to estimate storage tank sizes and costs at othe r airports. EPA’s normalized ADF usage amounts represent ADF amounts without any water dilution. ERG chose ADF usage as the costing basis for tank storage since the amount of tank storage needed is directly related to the amount of ADF applied for aircraft deicing, and ADF applied is a function of the frequency, duration, and intensity of precipitation events occurring at a particul ar airport during the course of a deicing season. In addition, the storage tank s at each of these airports ar e used to contain ADF impacted stormwater from deicing pads, ga tes and apron areas prior to disc harge to a POTW and/or on-site treatment, and therefore the hydr aulic capacity has likely been de signed with specific discharge requirements (e.g., maximum flow and equalized pollutant concentrations) in mind.

Capital and Operating Costs for Storage Tanks

ADF usage information, storage tanks volumes, co sts and normalized tank volumes and costs are provided in Table 1. The data in Ta ble 1 indicates the volume of stor age tanks at the five airports range between 1.5 million gallons and 8 million ga llons, with the average being approximately 4.6 million gallons. The average unit cost for st orage tanks calculated from the data in Table 1 is $1.67/gallon. The normalized storage tank volume, calculated from the data provided in Table 1 is 13.1 gal/gal ADF use/yr.

Table 1. Storage Tank Volumes and Installed Capital Cost for Various Airports Using EPA ADF Usage Estimates

Airport ADF Usage (gal/yr)* Total Storage

Tank Volume (gal) Storage Tank
Volume ADF Use (gal/gal/yr) Installed Capital Cost

(2006 $) Storage Tank Capital Cost ($/gal)

Denver 1 1,043,138 6,520,000 6.3 $795,000(a) $1.89

Pittsburgh 2 943,982 5,140,000 5.4 NA NA

Cincinnati 3 715,836 8,000,000 11.2 $9,440,000 $1.18

Portland 4 112,086 2,000,000 17.8 NA NA

Akron 5 60,246 1,500,000 24.9 $2,890,000 $1.93

Averages: 13.1 $1.67

NA – Not available. (a) Cost provided for one 420,000 gallon storage tank. 1 – Includes six 420,000 gallon storage tanks plus one 4 million gallon storage pond (Pond 003A). Includes 2.4 million gallon tank for Deicing Pads Charlie, Sierra Wide body, C, Cargo, FBO, Military, a 1.3 million gallon tank for Deicing Pads Echo, Y-North and Y-South, and a 1.4 million gallon EQ tank for the RO system. 2 – Includes one 8-million gallon high glycol concentration storage tank for runoff from deicing pads 3 – Includes one 2-million gallon storage tank for stormwater from gates, taxiways, snow pads and GRVs.
Stormwater contains BOD 5 concentrations greater than 1,000 mg/L. 4 – Includes two 750,000-gallon equalization tanks for storage of high glycol stormwater from deicing pads.Memorandum
October 2010 Page 3

To determine if the unit cost for above-ground st orage tanks was reasonable, ERG compared the $1.67/gallon unit cost to the cost for permanent storage tanks reported in the ACRP Fact Sheets 6 According to Fact Sheet 30 for aboveground permanent storage tank costs range from $1.25 to $1.75/gallon for tanks ranging in size from 500,000 gallons to 1 million gallons. Unit costs for storage tanks between 1 million and 2 million ga llons range from $1.00 to $1.50/gallon. ERG is not providing costs for underg round storage tanks due to co nstraints such as existing underground utilities or high groundw ater levels. Based on the da ta in the fact sheets, ERG believes the $1.67/gallon unit cost f actor should provide a conserva tive estimate of tank costs for airports which are space constrained.

Using the ADF use, the average tank volume per ADF use, and cost data in Table 1, ERG developed the following equation to estimate costs for storage ta nks at all airports based on

annual ADF use.

Storage Tank Capital Cost ($) =ADF Use gal/yr × 13.1 gal/ga l/yr × $1.67/gallon

Only limited data were available in the airport questionnaire database to determine the annual operating and maintenance (O&M) co st for storage tanks. One airport, Buffalo/Niagra reported annual maintenance costs for their storag e tanks ranged between $50,000 and $100,000. Using ADF usage information at the Buffalo/Niagra airport (281,836 gal/yr) an d the reported annual O&M cost for Buffalo/Niagra ($75,000/yr), ER G calculated the normalized annual O&M cost for storage tanks to be $0.27/gal ADF used/y ear ($75,000/281,836). Using the normalized cost factor, ERG developed the followi ng equation to estimate annual O&M costs for storage tanks at airports.

Storage Tank O&M Cost ($/yr) = ADF gal/yr × $0.27/gal/yr ADF

Summary

The equations included in this memorandum will be used in the airport deicing costs model to estimate option costs by airport. The input variab le for these costs is the estimated amount of ADF use by airport. The estimated storage tank cost s will be combined with other costs such as glycol collection vehicle and bloc k and pump recovery technologies.

6 Airport Cooperative Research Program, F act Sheet 30: Perm anent Tanks, 2009.