Guidance for Treatment of Airport Stormwater Containing Deicers (2013)

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79 For any given application of deicer treatment at an airport, there are likely at least two to three deicer treatment technologies that could provide the necessary degree of treatment and meet the airport’s regulatory compliance objectives. As a result, in many cases, cost of treatment becomes a differentiating factor. Treatment costs often need to be assessed at various points in the deicer treatment implementation process, from initial screening of alternatives through ongoing operations. Airports and airlines should solicit thorough cost estimates and be aware of the many challenges involved in obtaining accurate costs. Frequently encountered cost issues are shown in Table 8. Cost-related considerations are presented in this chapter for various aspects of deicer treatment assessment, implementation, and operations processes. 6.1 Cost Information Reported by Airports Cost information that was reported by airports during the research is provided in the airport deicer treatment system summaries contained in Appendix D. Where possible, notations have been made in these summaries to indicate the sources and limitations of the cost information. Great care should be exercised by guidebook users in drawing meaningful relationships between treatment costs at other airports and their airports. Such comparisons do not take into consid- eration the differences in system size, the costs of other deicer management system components, local economic conditions at the time of construction, and site infrastructure impacts. 6.2 Screening-Level Order-of-Magnitude Cost Curves To facilitate cost assessments during the treatment technology selection phase, screening-level cost curves have been incorporated into the technology fact sheets. Cost curves are presented for capital and operations and maintenance costs. Examples are provided in Figure 20 and Figure 21. The purpose of these curves is to provide order-of-magnitude guidance during the treatment technology screening phase. These cost curves were derived from unit costs for treatment system components considering only the typical technology features that are essential to the technology’s functions. Cost information from specific applications of the technologies at airports was consulted as a reference. The screening-level cost curves in the fact sheets are not recommended for use in the final selection of the technology or in the design phase, but should only be used as a guide in comparing the costs of various technologies during the treatment screening process. Beyond the screening process, site-specific cost estimates should be prepared that take into consideration the nuances of the technology application C H A P T E R 6 Determining Costs for Deicer Treatment

80 Guidance for Treatment of Airport Stormwater Containing Deicers Cost Issue Impact Often as-built treatment costs are not isolated from other deicer management costs. As-built treatment cost numbers reported in numerous publications, including regulatory documents, may not be accurate. Treatment costs are heavily dependent on the required size of the treatment system. Head-to-head comparisons of multiple airports’ treatment costs are not valid because sizes vary. The airport’s infrastructure and site conditions can affect treatment system cost. Cost estimates early in the treatment implementation process often under-represent impacts of site-specific infrastructure that become associated with treatment. Costs are often heavily affected by local economic conditions. Local factors such as proximity to raw materials or off-site processing can affect which treatment alternatives are most appropriate. The cost of treatment is directly related to the cost of other deicer management system components, especially storage. Compare treatment alternatives on a common basis (either as part of the total deicer management system cost or using a common basis for the remainder of the deicer management system). The relative proportion of capital versus operating costs can vary significantly among treatment technologies. It may be difficult to compare the cost and value of potential technologies without a life-cycle–based cost estimate. Projected annual costs are often underestimated. Carefully consider all factors that may contribute to annual costs. Table 8. Frequently encountered cost issues associated with deicer treatment. Figure 20. Example screening-level cost curve for capital cost of AFBR technology. Note: BCI = building cost index. $4 $6 $8 $10 $12 $14 $16 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 Co ns tru ct io n Co st (m illi on s) AFBR Treatment Load Capacity (lbs COD/day) Cost Basis Year: June 2012 BCI = 4,777 This curve has been prepared as a guide for comparing the costs of potenal deicer treatment. within the airport’s specific deicer management system, site infrastructure, and site-specific design features. The order-of-magnitude cost curves in the fact sheets were prepared for all technologies based on the pounds of COD per day that are required to be treated. Since all of the technologies have their individual differences, it may not be common practice to view costs primarily from the mass of COD to be treated. The cost guidance curves are presented as COD-load–dependent

Determining Costs for Deicer Treatment 81 to provide a common basis from which all technologies could be assessed. As technologies are evaluated in more detail during the treatment implementation process, the impact of other cost considerations, like impacts of flow rate, should be incorporated. The costs in the graphs in Figures 3 and 4 of the fact sheets were calculated in 2012 dollars, based on Cleveland, OH, cost data. Since location affects the cost of construction, the order-of- magnitude costs from the fact sheet cost curves should be adjusted to your location. RS Means Building Construction Cost Data contains state indices that can be used to adjust the construc- tion cost to the location of the treatment facility. This index is recognized in the industry and is commercially available. To adjust the cost data in the fact sheet graphs to a specific location, multiply the construction cost by the index that is specific to the project location and divide by the Cleveland, OH, index, which is 97.9. For example, assume the project has an estimated construction cost of $20 million, and the facility will be built in Fargo, ND. Fargo has a city index of 102.1. The adjusted construction cost for a facility to be constructed in Fargo would be: $20 million × 102.1/97.9 = $20.86 million In addition, the year that the project will be built also affects the cost of construction. This is commonly referred to as construction escalation. Engineering News Record’s Construction Cost Index (ENR’s CCI) provides a basis for adjusting costs. ENR’s CCI is based on labor and material construction costs from 20 cities and is calculated monthly. This index allows for the comparison of costs from one year to another. Construction escalation can vary widely. A review of the yearly history of construction escalation for the last 5 years will be helpful in predicting future annual escalation. A conservative approach would be to use 2% per year beyond 2012. The annual costs that are included in the fact sheet cost curves are also estimated in 2012 dollars. Just as the construction costs are adjusted for future years, the operating costs should be adjusted for future years to account for inflation. The Consumer Price Index (CPI) measures inflation by tracking price changes in goods and services from the purchaser’s perspective. From 2007 to 2012, Note: BCI = building cost index. $0 $50 $100 $150 $200 $250 $300 $350 $400 $450 $500 0 2,000 4,000 6,000 8,000 10,000 12,000 Es tim at ed A nn ua l O pe ra tin g Co st (t ho us an ds ) Activated Sludge Treatment Load (Pounds COD/day) This curve has been prepared as a guide for comparing the costs of potenal deicer treatment. Cost Basis Year: June 2012 BCI = 4,777 Assume 6-month operating period Avg. influent conc. approx. 1,200-mg BOD/L Figure 21. Example screening-level cost curve for activated sludge operations.

82 Guidance for Treatment of Airport Stormwater Containing Deicers the CPI increased 2% per year. A conservative approach would be to use 2% per year beyond 2012 to adjust the operating costs to future years. 6.3 Site-Specific Cost Calculation Considerations Considerations for calculating deicer treatment costs beyond the treatment technology screening phases are provided in the following. 6.3.1 Capital Cost Considerations Typical capital cost categories to consider for deicer treatment include: • Site investigation and land acquisition for treatment system site. • Treatment system site work. – Clearing. – Excavation. – Fencing. – Pavement. – Site stormwater controls. – Demolition. – Relocating/rebuilding existing infrastructure to accommodate treatment. • Treatment process costs. – Hydraulic control (pumps, pipes, valves, etc.) for system influent and process controls. – Treatment technology equipment and instrumentation. – Support system equipment and instrumentation. – Treated effluent discharge equipment and instrumentation. – Chemical and material storage. • Utilities and controls. – Electrical and other utilities. – Monitoring system. – Computer control system. – Communication systems. – Security and safety systems. • Building(s) to house the treatment technology and support systems. • Soft costs for general conditions, permits, and bonding. • General contractor profit and overhead. • Design and construction contingency. • Professional fees, which include engineering, legal, and construction administrative services. 6.3.2 Annual Cost Considerations In addition to the cost of construction, the annual deicer treatment costs for each year of the project’s lifetime should be determined. Those costs may vary, with costs during the start-up year likely to be higher, as construction and design related issues are worked out and as the operators learn the nuances of their particular system. Annual cost items to consider include: • Operator labor costs; • Maintenance repairs (labor and equipment); • Preventative maintenance; • Utilities fees (power, natural gas, water); • Sanitary sewer discharge fees; • Chemicals;

Determining Costs for Deicer Treatment 83 • Solids disposal; • Monitoring, permitting, and compliance fees; • Fees paid to consultants and contractors for operations and material handling; • Payback from sale of recycled glycol; and • Energy cost savings from methane captured from biological treatment and used as fuel. 6.3.3 Equivalent Annual Cost A method frequently used to jointly assess capital and operating costs is calculation of the equivalent annual cost. In the equivalent annual cost calculation, the cost per year of owning and operating the treatment system over its entire life span is calculated. The annualized cost calculation is as follows: Annualized Cost = (Capital Cost/At,r) + Annual Operating Cost Where: At,r = (1 - 1/(1 + r) t)/r, t = expected lifetime, typically 20 years, and r = percentage cost of capital rate expected (finance rate). Example: If t is 20 years and r is 5%, then At,r = (1 - 1/(1 + 0.05) 20)/0.05, and At,r = 12.46. Therefore, Annualized Cost = Capital Cost/12.46 + Annual Operating Cost. Use of equivalent annual cost will allow consideration of both capital and annual costs, allowing an easier head-to-head comparison of technologies that may be capital or annual cost-intensive to varying degrees. 6.3.4 Cost Assessments During the Alternatives Analysis Phase Beyond the technology alternatives screening phase, where order-of-magnitude costs from the fact sheets can be used, site-specific cost estimates should be prepared for capital and operations and maintenance costs. When performing an alternatives analysis, it is important to compare the treatment technologies on a consistent design basis using the same basis-of-design capacity data, governing effluent criteria, stormwater characterization criteria, and, when applicable, the same site and operations criteria. It is also important to note that cost calculations during the alterna- tives analysis phase are typically not detailed enough to serve as engineering cost estimates, and contingencies as high as 40% may need to be applied. 6.3.5 Cost Assessments During the Design Phase During the design phase, engineering cost estimates are typically developed at design milestones such as the 30%, 60%, 90%, and 100% design completion marks. The owner may ask for an engineer’s cost estimate prior to the project bidding. The design phase cost estimates are typically completed by professional cost estimators with support from the engineering staff. The cost estimates prepared during design are based on individual items and their quantities associated with individual technical specifications. These estimates are based on the anticipated year of construction and are priced consistent with the geographic construction market. These estimates help to maintain the owner’s budget and serve to predict the contractor’s bid.

84 Guidance for Treatment of Airport Stormwater Containing Deicers 6.4 Technology-Specific Cost Considerations 6.4.1 Cost Considerations for On-Site Biological Treatment Technologies On-site biological treatment systems typically have higher capital costs and lower operating costs than other deicer treatment technologies. Many times, biological treatment systems can rely on their core processes to reach the desired effluent concentrations, eliminating the need for additional polishing treatment processes. Capital costs for biological systems typically include: • Biological reactor (e.g., concrete basins, lined basins, earthen basins, and enclosed tanks); • Storage tanks for water, chemicals, and solids; • Pumps for stormwater conveyance, solids, chemicals, and sampling; • Blowers for aeration (aerobic only); • Equipment for process management (e.g., heat exchangers, pH adjustment, boilers, and air compressors); • Piping for water, steam, air, chemicals, solids, and gas; • Biological solids settling and solids dewatering equipment; • Instrumentation for process monitoring; • Computer control system; • Lab equipment; and • Buildings and associated structures, including maintenance support equipment. There is often a balance between complexity, land requirements, and use of a building in biological treatment. Highly efficient technologies like the AFBR require more complex controls and a building to house the main treatment equipment, but they have small footprints. Less efficient technologies like aerated gravel beds have less complexity and do not require a building to house the entire treatment system, but they require significantly more land. Some technologies can operate with or without buildings, and use of a building is an operator preference. A building may help reduce the heat losses of some processes, prevent freezing of critical equipment, and provide space for a lab to monitor the treatment. With anaerobic systems, the methane in the biogas generated by the biological degradation can be captured and burned as fuel to heat the influent water, isolating the system from weather effects. This isolation further reduces the needed treatment system footprint because accommo- dations do not have to be made in the sizing of the treatment system to account for cold weather. Treatment Tips Estimating Treatment Costs • Be aware of the risks in using cost data from other airports’ treatment systems. • Choose treatment size (capacity) carefully and realize that it is the most significant cost factor. • Compare treatment technology alternative costs on a common basis with a clear understanding of how other deicer management system component costs are factored in. • Consider using an equivalent annual cost approach that considers initial capital costs and the potentially variable annual operations and maintenance costs.

Determining Costs for Deicer Treatment 85 The methane content in anaerobic digestion biogas typically ranges from 50% to 75%, whereas natural gas contains approximately 95% to 98% methane. Some modifications to burners may be necessary to burn biogas methane instead of natural gas, but systems are available that are capable of burning either fuel. Handling of excess biological solids is an important cost consideration when comparing bio- logical treatment technologies to each other. All biological technologies produce additional bio- logical solids. For some technologies (aerated gravel beds and the related reciprocating gravel beds), the systems are operated with slow-growing bacteria, which minimizes the need to pro- cess biological solids. Other biological treatment technologies with faster growing bacteria and large capacities generate more solids and require a step for removing biological solids from the treated water, potentially followed by dewatering and disposal. The extent to which these steps are needed depends on the quantities generated and whether the POTW will accept discharges of solids (measured as TSS). If the POTWs will accept treated discharges containing solids, then the biological solids processing that is required is minimal. Arrangements could also be made for on-site digestion and on-site land application of biological solids to reduce biological solids pro- cessing costs. When comparing the quantities of biological solids to be produced, take note that aerobic treatment systems produce approximately 10 times more biological solids than anaerobic systems. On-site biological treatment technologies should have at least 20-year lifetimes. Many biological treatment facilities in other industries have lasted far longer. The operating costs for biological treatment facilities for airport deicer stormwater are primarily associated with the following: • Operators (typically one to two). • Power for pump and blowers. • Biological solids disposal. • Chemicals for supplying nutrients and adjusting pH. • Monitoring of system performance. • Miscellaneous costs for natural gas, potable water for cleanup, and maintenance. Significant maintenance costs should be anticipated for the electromechanical equipment (pumps, blowers, motors, controls, etc.). Systems that incorporate attached-growth (fixed-film) processes where the biofilm grows on a media provide good treatment efficiency, but the means for addressing potential solids buildup and clogging of the media should be understood. Some technologies have built-in means of removing solids (MBBR, AFBR), so clogging is not an issue. Consideration should be given to possible costs associated with future larger-scale unclogging of aerated gravel beds and passive facultative systems. Clogging in those systems can be managed with careful controls. See the fact sheets for AFBRs, aerated gravel beds, aerated lagoons, MBBRs, and passive fac- ultative treatments for additional details on biological technology costs. 6.4.2 Cost Considerations for Discharges to POTws POTWs will charge fees to all users (residential, commercial, and industrial) to offset their costs of treatment based on discharge volume and normal pollutant strength (as defined by the POTW for domestic sewage). POTWs may also establish additional fees applicable to IUs (i.e., the airport) only, which cover costs of the industrial pretreatment program administration and possibly costs of monitoring performed by the POTW pretreatment program staff. POTWs typically will also establish surcharges for extra-strength discharges to offset their additional treatment cost for discharges that exceed normal strength. Surcharges are typically established for BOD (or COD) and TSS, and often for ammonia. The surcharge cost is applied based on monitoring results for the amount of pollutant that exceeds the surcharge threshold concentration (i.e., the normal-strength

86 Guidance for Treatment of Airport Stormwater Containing Deicers concentration established by the POTW). Airport stormwater from aircraft deicing activities would typically exceed the surcharge concentration threshold for BOD/COD, but not for the others. Airport stormwater from airfield (pavement) deicing using urea-containing compounds would typically exceed the surcharge concentration threshold for ammonia/TKN as well as BOD/COD. Costs are unique to each POTW based on its specific circumstances and costs of providing service, including capital debt service. Accordingly, comparison of POTW costs from other locales is not meaningful. The POTW’s user charge structure and rates are typically developed based on an engineering/financial evaluation of the cost of services. The rates are authorized by the local political entity that has financial responsibility for the POTW (e.g., city, county, or separate wastewater/sewer agency or authority). It may be possible to negotiate a specific rate structure for the airport as a separate class of industrial user. The POTW must have uniform and equitable rates for all users within a class, but it may establish different rates for different classes of users. The rates charged by POTWs are subject to change, and in recent years many POTWs have increased rates substantially to help cover the costs of required infrastructure changes associ- ated with their own regulatory compliance, failing infrastructure, and growth. Some POTWs have increased rates by as much as 10% per year in the last 5 years, and even more when signifi- cant capital projects have been necessary to meet regulatory needs. Many POTWs are currently implementing costly long-term control plans to reduce wet weather pollutant discharges, and the associated costs are incorporated into discharge rates charged to all users. Airports interested in discharging to a POTW should not only negotiate current rates, but should take into consid- eration possible rate changes in the future. The POTW rate increases should be anticipated for the same period as the anticipated life span of potential on-site treatment systems that may be installed. For example, consider the case of an alternatives analysis featuring a choice between an on-site activated sludge treatment technology and a POTW discharge with no on-site treatment. If a 20-year life span for the on-site activated sludge system is used in calculating life-cycle costs, then rate increases associated with POTW discharges should also be considered over a 20-year period to get an apples-to-apples comparison of costs. One significant issue from the POTW’s perspective is that the treatment capacity necessary to treat deicer-affected stormwater is generally needed only during the deicing season and would be unused during the remainder of the year. While the variable portion of operating costs would not be incurred when this treatment capacity is unused, the fixed operating costs and capital debt service still must be paid continuously. See Fact Sheet 109 for additional details on POTW costs. 6.4.3 Cost Considerations for On-Site and Off-Site Recycling One of the 11 treatment technology options is discharge or transport of high-concentrate deicer to a privately run facility for completing the glycol recycling operation. Three other treat- ment technologies (mechanical vapor recompression, reverse osmosis, and distillation) are most frequently associated with on-site glycol recycling activities. For many recycling-based systems, airports will contract with vendors and pay ongoing fees. For these technologies, the capital costs are typically lower than for biological treatment systems, but operating costs are higher. On-site recycling is more economical the greater the volume of ADF sprayed at the airport and, more importantly, the larger the volume of glycol that can be captured at the airport for recycling. The greater the volume reclaimed, the larger the volume of product that can be sold to generate revenues to offset capital and operating expenses. When compared to an off-site recycling option, a cost analysis can be conducted to determine if on-site recycling is a more economical option based on the distance to the off-site facility and the volumes of glycol generated from the airport.

Determining Costs for Deicer Treatment 87 The costs to transport and treat at an off-site location are compared to the capital investment for an on-site facility, recycling equipment, and operating expenses. Following are considerations for determining costs for an on-site recycling facility: • Capital investment. Even if recycling equipment is leased, there may be capital costs to the airport for buildings, piping, pumps, storage, and other elements fixed at the site. • Length of contract term or project. If a recycling service provider invests in the manufacture of new equipment and incurs the up-front fees associated with installing and delivering recycling equipment, the fees will have to be recovered in a shorter time frame, usually driving up the cost to the airport. • Volume of glycol that can be reclaimed. Volume captured is factored into the cost calculations to determine how much revenue can be generated from glycol sales to offset expenses. In addition, if higher volumes of glycol can be processed over a longer season, the unit price to recycle goes down. However, in the event of a light winter, the costs to treat at an on-site facility are more or less fixed. This means that whether the winter results in the collection of glycol-affected stormwater or not, an airport will incur the costs associated with this operational readiness. • The value of glycol. Glycol prices fluctuate based on supply and demand. This risk must be factored in. • Permit limits and monitoring requirements. In cases where there are permit limits for glycol for discharges to surface waters (e.g., less than 100-mg/L PG or EG), costs for treatment can rise because additional processing equipment, such as membrane technologies or two-stage processing, is needed to achieve lower effluent concentrations. Lab testing, analytical fees, and other operating costs can also vary based on permit requirements. • Utilities. Costs for utilities are site specific and vary across the country. • Operations support overhead. Generally, the larger the recycling processing site, the larger the base of core personnel that needs to be retained on an annual basis—even if the processing season is 7 to 8 months. In general, if less than 200,000 to 300,000 of gallons of spent ADF with concentrations between 1% and 25% PG or EG are collected, then on-site recycling is not cost-effective, although off-site recycling may be an option. At greater volumes, the glycol transportation costs to the off-site facility can be excessive, and a number of benefits can be recognized with an on-site recycling option. Off-site recycling may be subject to unpredictable weather conditions affecting the ability to transport the glycol, resulting in potential storage issues at the airport. With on-site recycling, this issue can be avoided, and the staffing designated for the recycling operations can provide additional services that support effluent containment, collection, testing, reporting, and other airport functions. Large-scale on-site recycling operations have the potential to reach a break-even point to cover expenses associated with glycol recovery, or in a best-case scenario, provide positive revenue generation. Also, if an airport installs on-site recycling capability, there may also be an opportu- nity for that airport to act as a centralized recycling facility for other airports in the area, assuming that outside fluids can be accepted. Treating spent ADF from other airports gives the host airport the ability to maximize facility resources and reduce the costs associated with its glycol recycling program. For smaller commercial airports and military installations that generate a low volume of spent ADF, on-site recycling can be cost prohibitive. Trucking of fluid to an off-site recycling facility can be advantageous when considering the capital investment for a recycling facility, the processing equipment, and associated operating expenses. These costs can be avoided by providing on-site storage for spent ADF as a temporary measure to handle volumes generated from precipitation- related deicing events. After an event has subsided, the fluid can be trucked to a regional recycling

88 Guidance for Treatment of Airport Stormwater Containing Deicers center. Depending on the distance to the off-site facility and the volumes of glycol generated from the airport, a cost analysis can be conducted to determine if this option is the most economical. Many small airports can benefit from a regional recycling facility by avoiding the capital invest- ment and fixed operating expenses. In many cases, each airport that uses a centralized recycling facility may only pay a price per gallon for transportation and recycling. The advantages to the airport are that it does not have fixed expenses directly related to recycling, and it only pays for the volume treated each season. See the fact sheets for mechanical vapor recompression, distillation, reverse osmosis, and private recycling facilities for additional cost information.