TO: Brian D’Amico, USEPA/OW/EAD

FROM: Mary Willett, ERG

DATE: June 16, 2011

SUBJECT: Glycol Collection Vehicle and Plug and Pump ADF Collection Efficiency

Introduction

Collection and control of spent deicing fluid is the primary pur pose of most airport deicing control programs. EPA performed a review of airport deicing co llection operations to estimate the efficiency of glycol collection vehicle (G CV) and plug and pump t echnologies in collecting available spent aircraft deicing and anti-icing fluid (ADF). The purpose of this memorandum is to document the results of this review.

Description of GCV Technology

GCVs are specially designed vehicles that re move stormwater contaminated with deicing materials from airport deicing pads and gate locations by vacuuming liquid from pavement surfaces. GCVs help prevent ADF losses that occu r through evaporation and/or direct discharge, and allow for collection of ADF-contaminated stormwater for treatment or disposal. Drain

covers that bond to surfaces to quickly seal off drains are often used in conjunction with GCVs in aircraft deicing areas to allow the GCVs to collect high concentra tion spent deicing fluid.

There are two basic design approaches in commer cial GCVs: truck chassi s or trailer mounted. The truck chassis designs are adap tations of the street sweeper concept, with a vacuum unit, vacuum/sweeper head, and storage tank all m ounted on a single self-propelled vehicle. Typically, a separate engine powers the vac uum system. Trailer-mounted designs have the vacuum unit, collection head, and storage tank on a towed platform with power provided by either an engine mounted on the trailer chassi s or a power take-off from the tow vehicle, typically a tractor.

GCVs help prevent ADF-contaminated stormwater from reaching unpaved areas where infiltration could occur a nd from contaminating surrounding waterways. Once ADFcontaminated wastewater is vacuumed from airpor t surfaces, it is typically transported to an onsite storage facility (either temporary or permanent) where the airport can then treat and discharge, or ship the waste offsite. In addition, some airports with collection and conveyance systems or plug and pump, will have a designate d area where the GCV can discharge into the collection system, allowing the existing infrastructu re to convey the materi al to final storage.

Description of Plug and Pump with GCV Technology

Plug and pump collection systems are generally com posed of devices and e quipment that alter an airport’s existing storm drain sy stem to contain and collect AD F-contaminated stormwater toMemorandum June 16, 2011 Page 2 of 5

prevent it from entering the storm drain system. These systems include, but are not limited to, temporary blocking devices at stor m drain inlets, and/or installa tion of shutoff valves in the storm sewer system. Some airports use storm drain inserts or plugs to clos e the drains and allow the collection of ADF-contaminated stormwater w ithin the existing airport stormwater drainage system. When aircraft are undergoing deicing/ anti-icing, the inserts ar e installed to force contaminated stormwater to pool in drainage piping until the st ormwater can be vacuumed or pumped out. This practice prevents manholes and stormwater piping from overflowing. Once deicing/anti-icing activity ends and the contamin ated stormwater is re moved, the storm drain inserts can be removed, or deactivated allowi ng uncontaminated stormwat er to pass through the drain.

Plug-and-pump collection systems are applicable to airports that deice at the gate and may be utilized to convert ramp areas (cargo, feeder, taxiway etc.) in to deicing areas. Commonly, a plug and pump system is operated in conjunction with GCVs or a tanker truck with pumps which collect the deicing stormwater that builds up behi nd the drainage block during the deicing event. Additionally, GCVs may be used outside of the blocked area to collect ADF contaminated stormwater to enhance what can be co llected through the pl ugging operation alone.

GCV and Plug and Pump with GCV Collection Efficiency

EPA used estimates of an airport’s Type I and IV ADF usage 1 to calculate the volumes of applied and available ADF at airports that utili ze GCVs and/or plug and pump technologies with GCVs. Available ADF refers to the quantity of a pplied ADF that is available for collection. Not all applied ADF is available for collection du e to ADF adherence to aircraft surfaces, evaporation, wind losses, and wheel tracking. EP A has conservatively estimated available ADF to be 75 percent of applied type I deicing fluid and 10 percent of applied type IV anti-icing fluid, excluding applied ADF used for defrosting or de icing for safe taxiing. Figure 1 presents a detailed example of how EPA calculated available ADF.

1 ADF usage estimates can be found in section 9.2.1 of the TDD.Memorandum June 16, 2011 Page 3 of 5

Constants Percent of Type I Available = 75 Percent of Type IV Available = 10

Calculations Total Amount Applied = Type I + Type IV Total Amount Available = (Type I × Percent of Type I Available) + (Type IV × Percent of Type IV Available) Amount Collected and Controlled = Total Amount Applied × Percent Collection and Control of Available Percent of Available = Amount Collected and Controlled ÷ Total Amount Available

Example – Assume Type I Usage = 90 gallons Assume Type IV Usage = 10 gallons Total Amount Applied = 90 + 10 = 100 gallons Total Amount Available = (90 × 0.75) + (10 × 0.1) = 68.5 gallons Percent of Applied Collected and Controlled = 30 Percent of Available Collected = Amount Collected and Controlled ÷ Total Amount Available Percent of Available Collected = 44%

Figure 1. Example Calculation for Available ADF Collection Percentage

EPA’s Estimate of GCV Collection Efficiency

EPA did not identify collection efficiency data representing GCV use al one; however, data from Gerald R. Ford International airport (in Gra nd Rapids, MI) and Theodore Francis Green State airport (in Providence, RI) repr esent ADF collection systems th at are based predominantly on GCV use.

 The ADF collection system at Gerald R. Ford International airpor t uses two tow-behind glycol collection units in conj unction with catch basin insert s to collect aircraft deicing contaminated stormwater around the terminal gates and apron. The airport reported collecting 29 percent of all applied glycol during the 2005/ 2006 deicing season.

 Theodore Francis Green State ai rport uses 47 valved inserts in the catch basins of the primary and secondary deicing areas. The valv es are closed prior to deicing events and the deicing stormwater is collected into m obile collection units and stored onsite for transportation to off-site recovery. Mass bala nce data on glycol us age and collection at Theodore Francis Green State airport between 2002 and 2006 indicate that its GCV based system annually collects betw een 26 and 48 percent of all applied glycol.

Table 1 presents the efficiencies reported by these two airports and the estimated collection efficiency for available ADF which ranges from 38 to 71 percent.Memorandum June 16, 2011 Page 4 of 5

The Transportation Research Board (TRB) Air port Cooperative Research Program Report No. 14, Deicing Planning Guidelines and Practices for Stormwater Management Systems reports collection efficiencies of betw een 23 to 48 percent for GCVs. Th e systems represented in the TRB report used GCVs in combination with catch basin inserts, plug and pump technology, and/or apron systems. The ranges presented in th e report represent higher collection efficiencies than those associated with a plug and pump syst em; however, all of thes e data points include technologies that would result in higher collection efficiencies than a GCV alone. Based on these data EPA has conservatively estimated that a GC V is able to achieve approximately half the collection of a plug and pump with a GCV, or 20 percent of the available ADF.

EPA’s Estimate of Plug and Pump with GCV Collection Efficiency

EPA reviewed performance data from General M itchell International airport (in Milwaukee, WI) to evaluate the collection efficiency of pl ug and pump with GCV use. General Mitchell International airport uses a drain diversion syst em to separate the ADF-contaminated wastewater from other stormwater. When deicing operations ar e taking place, the drains in the deicing areas are closed. The airport uses the fo llowing drain divers ion devices:

 Sewer balloons, which are thick latex balloons covered in heavy canvas. The balloons are suspended underneath the gr ate of the storm drains during the winter season. During deicing events, maintenance trucks inflate the balloons to block the storm drains. The airport currently has eight sewer balloons.

 Catch basin inserts, which are inserted into the storm drain to block ADF-contaminated wastewater from entering. The airport currently uses catch basin inserts in two locations.

 Storm sewer shut off valves are used at four locations at the airport.

 Two GCVs are used for ADF contaminated st ormwater collection - one is a traditional truck-based GCV and the othe r is a GCV unit (a V-Quip Ramp Ranger) that is towed behind a tractor.

General Mitchell International ai rport reported a colle ction range from 2002 to 2006 of between 22.5 and 33 percent of applied ADF. Table 1 below presents the range of efficiencies reported by this airport and the estimated collection efficiency for available ADF, which ranged from 33 to 48 percent.

EPA’s data points are similar to those summari zed in the Transportation Research Board (TRB) Airport Cooperative Research Program Report No. 14, Deicing Planning Guidelines and Practices for Stormwater Management Systems. That report presented collection efficiencies between 20 and 35 percent of applied ADF for plug and pump systems. At proposal, EPA estimated that plug and pump with GCV systems use would co llect 40 percent of available ADF. When adjusted for rounding, the mean of the data above is approximately 40 percent. As such, EPA has determined that a well operated plug and pump system (in conjunction with GCVs) should be able to colle ct 40 percent of the available ADF.Memorandum June 16, 2011 Page 5 of 5

Table 1. GCV and Plug and Pump with GCV Collection Efficiencies and Available ADF Collection Calculations

Airport ID Airport Name GCV Percent Collection Efficiency of Applied ADF 2 Applied ADF 3 Available ADF (Type I Applied x 0.75) + (Type IV Applied x 0.10) Percent Collection of Available ADF Type I Type IV

1058 Gerald R. Ford International 29 84,414 12,760 64,587 44

1121 Theodore Francis Green State 26 to 48 133,887 16,240 102,039 38 to 71

Airport ID Airport Name Plug and Pump w/ GCV Percent Collection Efficiency of Applied ADF 2,4 Applied ADF 2 Available ADF (Type I Applied x 0.75) + (Type IV Applied x 0.10) Percent Collection of Available ADF Type I Type IV

1136 General Mitchell International 22.5 to 33 137,650 15,294 104,767 33 to 48

2 Summary of Current State of th e Practice on ADAF-Affect ed Stormwater Management, June 2007, CH 2 MHill (DCN AD00896)

3 See Table 9-3 of Technical Development Document for the Final Effluent Limitation Guidelines and Standards for the Airport Deicing Category. (DCN AD01279) 4 August 8, 2006 Presentation by Greg Failey, MKE Study for AAAE August 2006 Deicing Conference. (DCN AD01265); the range presented represents the most recent years.