## MEMORANDUM

TO: Brian D’Amico, EPA EAD

FROM: Mark Briggs, ERG

DATE: November 16, 2011

SUBJECT: Estimated Capital and O&M Costs for a Plug-and-Pump Collection System

This memorandum documents the methodology that EPA used to estimate both the capital and annual operating and maintenance (O&M) costs for an airpor t to implement a plug and pump collection system for stormwater contaminated with aircraft deicing fl uid (ADF). EPA used the same approach to estimate

costs for the final rule as for the proposed rule. EPA did not receive any comments or additional data following the proposal on its plug and pump costi ng methodology or underlying data. EPA developed this memo to more clearly explain its approach.

As a point of clarification, this memo describes EPA ’s costing approach for the components of plug and pump including GCVs. Costing for other components of the technology basis such as additional piping, land, and equalization/storage and treatment are detailed in separate memos.

Plug-and-Pump Technology Description

The primary objective in employing plug and pump systems is to intercept deicing stormwater close to the source, often using existing storm sewers for temp orary inline storage. This approach facilitates costefficient collection of deicing contaminated st ormwater and can improve the economy of glycol treatment/recovery systems. The plug and pump coll ection system utilizes the airports existing storm water collection system infrastructure in combination with glycol collection vehicles (GCVs) to contain and collect ADF contaminated stormwater. The plug and pump system operates by placing either temporary inflatable balloons or storm sewer shutoff valves in the existing storm sewer system. During deicing events, the balloons are inflated and storm sewer shutoff valves are closed, trapping the ADF contaminated stormwater in the collection system. Vacuum trucks pump the trapped contaminated stormwater from the storm sewer system and transport the liquid to on-site storage. In addition, catch basin inserts can be placed into manholes to collect ADF contaminated stormwater. The typical plug and pump system commonly uses GCVs to sweep ADF contaminated stormwater from the gate, ramp and apron area surfaces following application. The glyc ol recovery vehicles deliver the ADF contaminated stormwater to on-site storage/equalization. Bloc king mechanisms are generally opened or removed during non-deicing periods to allow normal drainage of non-impacted stormwater (DCN ACRP Footnote 24).

System Components

Plug and pump system design depends on the airport c onfiguration. Generally, the existing storm sewer system piping is used to contain ADF until it can be removed by a GCV, vacuum truck, or is pumped directly to a storage/equalization tank. For airports that do not have sufficient storm sewer piping in deicing areas, additional piping may be required. Sewer balloons, catch basin inserts, and diversion valves, and real-time monitoring can be installed in the system to contain ADF and allow release of uncontaminated stormwater following a deicing event. Permanent or temporary storage/equalization

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tanks are also required to store the glycol contaminated stormwater until either recycling or treatment. Sewer ballons, catch basins, and diversion va lves are described in more detail below.

Sewer Balloons

Sewer balloons are inflatable bladde rs and can be installed almost anywhere there is access to the storm

sewer. Sewer balloons can be inflated with either air or water and provide a simple and effective storm sewer pipe plug. Sewer balloons do require secure an choring within the storm sewer system to prevent them from being lost beyond the immediate manhole area

Catch Basin Inserts Catch basin inserts provide a physical barrier for containing deicing stormwater on the surface of the apron to allow time for collection or for testing prior to its release. Inserts are typically installed in catch basins that receive surface drainage from aircraft deicing areas and are capable of being readily closed prior to the start of the deicing event and opened s ubsequently to allow clean aircraft deicing laden stormwater to enter the storm sewer system.

Different types of physical barriers are available. Th e simplest method consists of a molded plastic dropin panel with a depression in the bottom that serv es as a sump. These have limited practicality because they require that the storm grate be lifted to inst all or remove the barrier. A more sophisticated and practical approach employs a metal sump installed under a catch basin grate and fitted with a butterfly valve that can be operated with a T-handle from the surface. Inserts typically remain closed during the deicing event, although many operators keep them closed longer to prevent dry weather discharges of

deicer.

Diversion Valves Diversion valves provide flexibility in managing st ormwater with varying deicer concentrations. Diversion valves may be used to contain water in the collection system for plug and pump, or direct stormwater to one of several destinations, including tr eatment, storage, or discharge. Installations vary in complexity from manually operated valves to automa ted diversion systems that operate based on realtime monitoring. Manual diversion valves are typically operated based on deicin g conditions or weather observations (e.g., containment or diversion to storag e during deicing events and to surface water between events). Automated valves may allow flows to be managed more precisely during deicing events. These valves may be actuated by a supervisory control an d data acquisition (SCADA) system, which may make diversion decisions based on online monitoring or ma nagement system information. Several valve types are suitable for use in deicing stormwater containment systems. In general, resilient gate valves or plug valves are preferred. Ultimately, any valve used for deicing stormwater must have zero leakage and be chemically compatible.

Simple, manual diversion systems are appropriate for ai rports with relatively simple deicer management systems that are operated infrequently or do not requi re changes often, and airports that collect and discharge all deicing stormwater to a single des tination. More sophisticated and costly automated approaches may be justified at airports with manage ment systems where operation can be optimized using concentration-based flow segregation. Automatic valv es are often used in applications requiring frequent

diversion.



### Cost Methodology

Where EPA determined an airport would not m eet a 40% collection requirement based on its existing technologies, EPA estimated both capital and annual operating and maintenance (O&M)

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costs for such airports to em ploy plug-and-pump collection (the technology basis for the 40% collection requirement). The follo wing describes how EPA estimated costs for such airports.

Available Data Although EPA requested capital and operating cost data for all types of ADF collection and treatment technologies in the Airport Ques tionnaire (DCN AD00354), no cost data were provided regarding plug and pum p. In addition, the airport industry did not provide any additional cost information during the comment period on the proposed airport deicing rule. Instead, one airport provided capital cost info rmation on their plug and pump type collection system (General Mitchell International Airport - Milwaukee) during th e site visit, and one airport provided information on their annual co st for plug and pump (M inneapolis-St. Paul International Airport -Minneapol is) during subsequent contacts.

Capital Costs Data to estimate capital costs was provided by General Mitchell Airport (MKE). During the 2005 deicing season, MKE controlled deicing contamin ated stormwater from three outfalls. To perform the collection, MKE employed eight (8) se wer balloons, four (4) storm sewer shutoff valves at, and two (2) catch ba sin inserts (DCN AD00772). In addi tion, this airport utilized two (2) GCVs for ancillary glycol collection; one is a traditional truck-based GCV and the other is a

GCV unit that is towed behind a tractor. MKE estimated capital cost for its plug-and-pump system (including the GCVs) to be approximately $790,000, see Table 1.

Table 1. 

### Estimated Capital Cost for the Bloc k-and-Pump System in Milwaukee

Equipment Number in

Service Unit Cost (2006$) Total Capital Cost (2006 $) GCVs 2 $360,000 1 $720,000 Sewer balloons 8 $4,450 3 $35,600 Shut-off valves 4 $8,100 2 $32,400 Catch basin inserts 2 $1,400 1 $2,800 Total: $790,200

1. Workshop: Best Management Practi ces for Airport Deicing Stormwater

2. RSMeans Heavy Construction Cost Data, 2002 (24” Diameter Knife Gates with Handwheel)

3. Includes 24” diameter balloon, hot tapping insert syst em, inflation hose, and c ontrollers and valves from Peterson Products, Co., Fredonia, Wisconsin.



### To use this information to estimate capital costs for other airports, EPA normalized the MKE capital costs based on the number of deicing outfalls, see Table 2. 

### EPA assumed that the number of deicing outfalls would relate to the number of areas where aircra ft deicing occurs, so that in general an airport that has a greater number of discontiguous deicing areas will have a greater number of deicing outfalls. EPA estimated that more deicing area s would indicate the need for additional costs associated with removing ADF from those areas

As shown in Table 2, capital costs to install a pl ug and pump system that will achieve 40% collection approximate $263,400 per deicing outfa ll . EPA attempted to provide conservative cost estimates, so if a

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model facility’s baseline level of collection (see DCN ADF Collection) was greater than 0% but less than 40%, EPA applied full capital costs as if no collection technologies had been employed at baseline. EPA took this approach because it does not have data to estimate incremental costs for a facility with some baseline collection system that does not conform to plug and pump to upgrade to a system that does conform with the plug and pump technology that forms the basis of a 40% collection requirement. This approach likely overestimates costs for some facilities. Table 2. Normalized Capital and Operating Costs for the Block-and-Pump Collection System

Airport Deicing

Outfalls Total Capital Cost (2006 $) Capital

Cost /

Outfall ($/outfall) Milwaukee 3 $790,000 $263,400



### Operating & Maintenance Costs Data to estimate O&M costs was provided by Milw aykee Airport (MKE). As reported by in an e-mail to EPA (DCN Furhman email), MSP c ontrolled deicing contaminated stormwater discharges from five (5) outfa lls (DCN AD00793). MSP contract s out its collec tion to a third party. To perform the collecti on, the third party provides all of the equipment and employs plug and pump operations including plugging the associ ated drainage pipes and pumping out these

drains with dedicated vacuum pumping trucks. The plug and pump system at MSP does not, however, include GCVs. MSP reported that the a nnual cost for this service are approximately $1,300,000 1 

### . Due to the limited cost data on plug and pump technologies pr ovided by airports in the questionnaire responses, EPA used the annua lized cost information from MSP to estimate O

and M costs associated with plug and pump operation.

Clearly, MSP’s annual costs overstates operation and maintenance costs alone because MSP’s costs also include amortization of the equipm ent and other none operation and maintenance related costs. Therefore, while the MSP cost s do not include operating and maintaining GCVs, EPA concludes applying the MSP costs is a ppropriate and will not underestimate anuual operation and maintenance costs associated with the plug and pump system that forms the basis of 40% collection because ope ration and maintenance of GCVs are likely less than the equipment amortization costs or something like that.

To estimate the O&M costs for other airpor ts for plug and pump collection, again EPA

normalized the MSP O and M costs based on the numb er of deicing outfalls . See Table 3. As shown in Table 3, an airport would spend $260,000 in O&M costs per deici ng outfall to operate and maintain a plug and pump system that would achieve the 40% collection requirement

.

Table 3. Normalized Capital and Operating Costs for the Block-and-Pump Collection System

Deicing Annual Operating and Normalized

Annual Operating and

1 These O&M costs include permit monitoring, glycol management, the pumping contractor, plus other miscellaneous costs (ERG, May 3, 2007).

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Airport Outfalls Maintenance Cost (2006 $) Maintenance Cost (2006 $) Minneapolis 5 $1,300,000 $260,000

Example Calculation

The following example shows how the cost model estim ated annualized plug and pump costs for the Port Columbus, Ohio airport based on the number of stormwat er deicing outfalls reported in the questionnaire. See the Economic Analysis (DCN XXXX) for details on how capital costs were amortized.

Number of ADF contaminated stormwater outfalls at Port Columbus: 7

Calculated capital cost per outfall: $263,400

Calculated O&M cost per outfall: $260,000

Total capital cost = $263,400/outfall x 7 outfalls = $1,843,800 Amortized plug and pump capital cost = $245,342/yr 2

Annual Operating and Maintenance Cost for Po rt Columbus: $260,000/outfall x 7 outfalls = $1,820,000/yr

Annual Cost for Port Columbus (annualized capital plus annual): = $245,342 + $1,820,000 = $2,065,342

2 See the final rule Economic Analysis for Effluent Limitation Guidelines and Standards for the Airport Deicing Category Document (AD01280) for a description of amortization of capital costs.