National Academies Press: OpenBook

Benefit–Cost Analyses Guidebook for Airport Stormwater (2019)

Chapter: Chapter 4 - Benefits

« Previous: Chapter 3 - Introduction to the Triple Bottom Line
Page 23
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 23
Page 24
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 24
Page 25
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 25
Page 26
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 26
Page 27
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 27
Page 28
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 28
Page 29
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 29
Page 30
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 30
Page 31
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 31
Page 32
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 32
Page 33
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 33
Page 34
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 34
Page 35
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 35
Page 36
Suggested Citation:"Chapter 4 - Benefits." National Academies of Sciences, Engineering, and Medicine. 2019. Benefit–Cost Analyses Guidebook for Airport Stormwater. Washington, DC: The National Academies Press. doi: 10.17226/25617.
×
Page 36

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

23 Identifying benefits and measuring their value are potentially the most diffi- cult parts of a BCA using the TBL. The process of identifying social and environ- mental benefits may be relatively new to many airports. As previously discussed, involving staff and stakeholders with the ability to evaluate the full range of proj- ect outcomes will help the airport conduct the best possible analysis of benefits. This chapter summarizes some of the primary drivers for stormwater infrastructure at airports and how the incentives relate to the potential benefits of a project. This chapter also highlights considerations to keep in mind when assigning value to benefits and identifies resources that may help the airport through this process. 4.1 Drivers for Airport Stormwater Projects Benefits associated with improvements to airport infrastructure include reductions in aircraft operation costs, passenger delays, and aircraft delays; airtime savings; and ground time savings. Airports will invest in stormwater projects for many of these reasons but also to comply with federal, state, and local regulations. The airport staff should also explore potential future changes to regulations (e.g., water quality standards). The benefits of a BCA should incorporate these drivers so that the results of the analysis reflect how well the airport achieves these priorities. 4.1.1 Relevant Regulations and FAA Guidance Regulatory compliance is often the primary reason for undertaking stormwater infrastructure projects at airports, and improved compli- ance with stormwater permit requirements can be a significant financial benefit (e.g., through avoidance of fines). New impervious area created C H A P T E R 4 Benefits Los Angeles International Airport noted that it has been subject to an LID ordinance enacted by the City of Los Angeles for the past 10 years that requires it to address the 75th-percentile of rainfall on newly built project footprints. The airport has also had stormwater projects that were part of a larger stormwater management initiative of the City of Los Angeles. Newark Liberty International Airport has a set of climate resiliency guidelines and sustainable infrastructure guidelines for project designs. Example Tool: FHWA INVEST The FHWA INVEST tool (FHWA, n.d.) describes mapping criteria to find the benefit and cost elements that are most critical and relevant to project goals.

24 Benefit–Cost Analyses Guidebook for Airport Stormwater during expansion projects, for example, can necessitate storm water infrastructure work for drainage and to remain in compliance with regulatory requirements. Both CWA (i.e., NPDES) requirements and FAA requirements can come into play. For example, inspections associated with FAA certifications may reveal issues to correct during stormwater infrastructure work. A few of the federal regulatory drivers that dictate airport stormwater collection, management, and treatment practices to ensure safe airport operations and environmental protection are summarized in Appendix C. In addition to the federal regulations and recommendations, state and local governments may also have requirements for airport storm water treatment and management. Facility managers will need to be aware of these and any other regulations pertaining to storm water management that could affect stormwater infrastructural design and associated benefits and costs. Environmental benefits associated with these regulations can include reduced runoff volume, peak-flow attenuation, and pollutant removal. Other benefits may include freeing up land through infra- structure designs with smaller footprints and reduction in water utility charges through stormwater harvesting. 4.1.2 Stormwater Management as an Aspect of Airport Sustainability Airports may incorporate sustainability and stewardship considerations into planning for drainage projects. Some airports are subject to municipal ordinances to use GSI or LID. Others undertake stormwater management initiatives that are beyond compliance or voluntary in nature. For example, stormwater projects may incorporate GSI practices as part of municipal or airport environmental sustainability goals; stormwater management can be seen as a natural component of an airport’s sustainability program. The benefits of these management approaches should be reflected in the BCAs of stormwater projects. Benefits could be performance related, similar to those described previously for regulatory requirements, or benefits could be reflected as the degree to which the project meets the airport’s or local ordinances. Benefits may also include gains in efficiency, such as reduction in use of potable water and energy efficiency (e.g., green roofs). Table 6 summarizes examples of FAA resources that provide guidance in sustain- ability considerations for stormwater airport projects. 4.1.2.1 Sustainability Master Plans Stormwater management is a common element of airport sustainability master plans (SMPs) and can include initiatives such as the following: Including Airport Sustainability in Project Selection Dallas/Fort Worth International Airport incorporates sustainability considerations qualitatively in the design phases of its projects, along with cost, feasibility, performance, and other traditional factors. Resource Description FAA Advisory Circular (AC) 150/5070-6B: Airport Master Plans Provides background on the consideration of sustainability and environmental impacts in airport projects. Encourages an increased focus on sustainability in airport master plans. FAA Order 5050.4B: National Environmental Policy Act (NEPA) Implementing Instructions for Airport Actions Provides guidance in identifying potential environmental impacts and complying with NEPA. FAA’s Airport Sustainable Master Plan Pilot Program Acknowledges that the many benefits of airport sustainability planning include improved water quality, and as such, water resources are an expected component of airport sustainability management plans. Table 6. FAA sustainability resources.

Benefits 25 • Evaluation of wastewater management strategies; • Water reuse; • Stormwater runoff management; • Replacement of stormwater pipes and installation of drainage swales to sequester tire rubber and heavy metals to prevent them from entering adjacent waterways; and • Biodiversity protection for indigenous plants (including mosses) and wildlife. Airports with sustainability plans or stormwater master plans have qualitatively assessed the value of sustainable practices at their facilities and can point to sustainability goals in those plans for justification of projects. 4.1.2.2 Managing Runoff from Industrial Activities Water quality can be protected by robust programs that address discharges from industrial activities such as fueling, washing, maintenance, construction, and deicing. These programs can be implemented as part of an airport’s stormwater projects, depending on whether the project needs to address any of these special activities. Common practices to address these activities are: • Collection of deicer-affected runoff, • Storage and disposal or treatment, • Incorporation of detention basins during construction projects to detain runoff and reduce pollutant discharges, and • Integration of dedicated washing facilities that drain to sanitary sewers. A BCA should incorporate benefits such as water quality improvements, regulation compli- ance, and operational efficiencies that might result from these practices. 4.1.2.3 Value of Innovation Although many stormwater management activities are regulated at the federal, state, and local levels, airports have adopted innovative approaches to reducing airport impacts on local storm systems as part of their sustainability strategies. From a benefit–cost perspective, investments in airport stormwater infrastructure have proven to be an economically viable means to signifi- cantly improve surface water quality, address community concerns, and enhance waste recovery rates. Airports have begun to turn to stormwater management practices that rely on natural or biological treatment methods (i.e., GSI), which reduce on- and off-site energy use and operating costs associated with traditional treatment methods. 4.1.2.4 Climate Resilience Climate Change Considerations: Example 1 Climate change and sea level rise are issues for some airports but not for others. San Diego International Airport is at low elevation and would not be able to counteract the effects of major sea level rise. Naples Municipal Airport is at an elevation of 3 to 7 feet, with water bordering two of its sides. Despite the potential risk, it currently does not explicitly include potential climate change implications in its project designs. Los Angeles International Airport, on the other hand, is coastal but is at a high enough elevation that it would not be flooded, and its design parameters are within the scope of projected climatic effects of the next 30 to 40 years. Newark Liberty International Airport takes sea level rise into account when considering the useful asset lives of its infrastructure.

26 Benefit–Cost Analyses Guidebook for Airport Stormwater Climate Change Considerations: Example 2 Minneapolis–St. Paul International Airport indicated that climate change considerations are included when it designs stormwater management infrastructure. The Minneapolis–St. Paul region has seen changes in its winters over the last 10 years, with less snow and more mixed precipitation. Minneapolis–St. Paul noted that most airports are considering the implications of these types of trends. Bangor International Airport also noted changes in winter weather and said that lack of stormwater capacity has become a concern. Kissimmee Gateway Airport indicated that it is paying attention to changing climate projections; it uses the 100-year storm as its benchmark and has made adjustments as new data become available. An emerging area of focus for airport sustainability practitioners is climate resilience. Severe storms and sea level rise both are consequences of climate change that pose direct threats to airport operations, particularly at coastal airports, and as such, have received considerable atten- tion in recent years. Adaptation of stormwater infrastructure is arguably the most critical ele- ment of an airport’s ability to cope with these effects. 4.2 Considerations for Valuation of Benefits 4.2.1 Operational and Non-Operational Benefits and Avoided Costs Successful stormwater management will result in operational benefits to the airport as well as other benefits that are unrelated to operations. Operational benefits are those that result from the effective removal of stormwater from surface areas. For example, if the project removes storm- water from runways, the project reduces the risk of flight delays and cancellations. The value of this can be expressed in terms of the avoided costs per enplanement of the delays or cancellations. The likelihood of effects on operations and costs due to flooding varies geographically according to climate and airport characteristics; it may become increas- ingly important due to climate change and the need to incorporate resil- ience into airport infrastructure. Other (non-operational) benefits of a project might include compliance with NPDES permit requirements and local ordinances and improving water quality through contaminant removal in stormwater discharge. Operational and non-operational benefits can be equally important, both in their effects on airport operations and their monetary value. In fact, environmental regulations often are key drivers of stormwater projects at airports. A common approach for valuing these benefits is to estimate the costs that they help the airport avoid. For example, storm- water infrastructure that allows runoff pollutant concentrations exceed- ing permit conditions would lead to penalties and fines. The monetary value of the benefits of a project that reduces pollutants in runoff is the avoided cost of these fines. This avoided cost represents both the value of the avoided environmental damage (in whole or in part, depending on the permit requirements) and the avoided financial risk to the airport. Benefits Recognized by the FAA The FAA recognizes several benefits in its BCA Guidance (summarized in Appendix B) that relate to airside, terminal, and landside capacity projects. Potential benefits related to stormwater projects may include: • Safety improvements, • Reduced delays, • Lower O&M costs, • Compliance with FAA standards (e.g., standing water and wildlife hazards), and • Environmental benefits resulting from bringing infrastructure into compliance with state or federal environmental regulations.

Benefits 27 4.2.2 Design Variations to Increase Environmental Benefits Many BMPs have considerable flexibility in design and are also the subjects of ongoing research and improvements. Airports can work with design engineers, researchers, state and local engineers, and per- mitting agencies to adapt or modify BMP designs to improve their envi- ronmental or social benefits in addition to meeting FAA regulations and airport stormwater management needs. By looking for opportuni- ties to improve infiltration, wildlife deterrence, pollutant removal, or other characteristics, overall project benefits can be increased. Addi- tional costs due to extra design efforts or purchase and installation of additional components may be offset over the life of the project by these benefits. By enhancing benefits and minimizing risks from airport-specific concerns, working with professionals to modify and optimize designs can help an airport make a stronger case for an innovative project. 4.2.3 Climate Change For stormwater infrastructure in certain parts of the country, future climatic conditions are anticipated to include increased variability and intensity of precipitation as well as more fre- quent flood events. These changes will lead to increased stress on stormwater systems. If an airport increases the capacity of its stormwater system through sizing of gray infrastructure components or implementation of GSI as part of a project, this can reduce the burden on exist- ing stormwater infrastructure. This will in turn reduce costs associated with replacing BMPs or needing to increase capacity at another time. Benefits can include savings in operational costs, passenger time and flight delays, social productivity losses, and real estate and leasing costs, as well as increased tenant income and expanding the aviation community. 4.2.4 Factors Affecting Uncertainties in Benefits Airport staff are encouraged to consider how well benefits are constrained and the uncertain- ties inherent in the values assigned to benefits. Benefits estimated from projects at non-aviation sites (including information from literature) or at airports with significant differences may carry a greater uncertainty than those based on in-house information. Airport staff are encouraged to consider the range of feasible values for each benefit and to maintain as much transparency as possible regarding uncertainties throughout the development of the BCA. Environmental benefits such as BMP performance (both quantity and quality) can be diffi- cult to quantify even in working BMPs. Literature values can be reviewed for general estimates, which may be sufficient for an initial assessment of alternative project designs. If a BMP will be engineered for pollutant removal (e.g., via selection of engineered media), pollutant removal can be better anticipated. If the stormwater system is modeled using the Storm Water Management Model (SWMM) (U.S. EPA, n.d.), for example, those estimates can be used. Benefits assigned qualitative values are inherently subjective. Uncertainties may be related to differences of opinion among staff as to how to assign values when using a scale; collabora- tive discussions among staff may be needed to reach consensus on qualitative values. Please see Chapter 6 for a discussion on incorporating uncertainties in a BCA. Examples of BMP Design Choices to Improve Environmental Benefits • Steep sides for ponds or constructed wetlands to reduce wildlife hazards • Sizing of a BMP to increase capacity for climate change considerations • Selection of native vegetation • Use of media with additional compost, zeolites, or other components to improve pollutant removal • Design of a sub-bed in a subsurface structure to enhance infiltration capacity

28 Benefit–Cost Analyses Guidebook for Airport Stormwater 4.3 Resources for Information on Benefits 4.3.1 Permitting Information The airport’s and other organizations’ permits are a source of information about the potential benefits of projects. Federal, state, and local regulatory offices may provide information about the potential cost of failure to comply with stormwater rules. Past fines, penalties, or other charges for the airport or other landholdings also can provide a basis for estimating the cost of future charges. 4.3.2 Resources Provided by EPA and Other Organizations Entities such as the U.S. EPA, the CNT, and the Water Environment Research Foundation (WERF) have made resources available through web sites, reports, and calculators that can help in identifying and assessing the benefits and costs of stormwater BMPs, including GSI and LID. Table 7 contains selected examples but is not intended to be comprehensive; see the References and Additional Resources section for a more complete listing of resources for approaching valu- ation of benefits. 4.3.3 Communication with Airports and Other Transportation Entities Airport staff may benefit from contacting other airports, port authorities, other transportation agencies (highway administrations), or other large landholders that have installed BMP types that the airport is interested in using. This may be especially valuable for learning about costs as well as challenges encountered during design, construction, and post-construction. Using this practical experience and obtaining information on unexpected O&M costs or other difficulties can help in planning for the life-cycle costs of a project. This type of communica- tion may be especially useful for airports interested in implementing GSI and LID. Suggested questions to pose to staff at other organizations are included in the Suggested Questions to Pose to Other Organizations text box. Where Can You Look? Who Can You Talk To? • Staff at state transportation agencies. • Sustainability master plans or annual reports for airports or other trans- portation agencies. • Databases providing information on projects [e.g., International BMP Database, Sustainable Aviation Guidance Alliance (SAGA) database]. • Keyword Internet search for relevant project examples. Suggested Questions to Pose to Other Organizations • How did they develop capital cost estimates for the project? • How did they approach O&M costs and life-cycle costs in general? • Did they do a BCA? • Did they face any challenges getting management or stakeholder buy-in on the project? If so, how did they address those? • Did they customize any design features to improve environmental performance or otherwise improve BMP feasibility or benefits for their facility? • Were there unexpected costs that arose during construction? • How has the project performed (if it has already been constructed)? • What benefits has the project brought or is expected to bring over its life span (financial, environmental, and social)? • How was the project financed?

Benefits 29 Organization Resource Description U.S. EPA https://www.epa.gov Green Infrastructure Cost–Benefit Resources https://www.epa.gov/green- infrastructure/green-infrastructure- cost-benefit-resources Links to examples of cost–benefit analyses and tools. Focused on communities. U.S. EPA https://www.epa.gov Opti-Tool: EPA Region 1’s Stormwater Management Optimization Tool https://www.epa.gov/tmdl/opti-tool- epa-region-1s-stormwater- management-optimization-tool Spreadsheet-based optimization tool used to estimate required pollutant and volume reductions at affordable costs. Focused on New England but can be adapted for use in other regions. U.S. EPA https://www.epa.gov National Stormwater Calculator https://www.epa.gov/water- research/national-stormwater- calculator Tool that estimates stormwater runoff reduction of various green infrastructure and LID practices. CNT https://www.cnt.org Green Values Stormwater Toolbox https://www.cnt.org/tools/green- values-stormwater-toolbox Helps to evaluate sustainable design opportunities based on research into cost- effectiveness of green infrastructure. CNT https://www.cnt.org The Value of Green Infrastructure https://www.cnt.org/publications/the- value-of-green-infrastructure-a-guide- to-recognizing-its-economic- environmental-and Provides specific approaches for quantifying benefits. Includes case study examples of analyses. International Stormwater BMP Database International Stormwater BMP Database http://www.bmpdatabase.org Includes a database of over 600 stormwater BMP studies, summary publications related to BMP performance (i.e., pollutant removal), and other useful resources and tools. NOAA https://coast.noaa.gov A Guide to Assessing Green Infrastructure Costs and Benefits for Flood Reduction https://coast.noaa.gov/digitalcoast/ training/gi-cost-benefit.html Provides guidance on recording the costs of flooding, projecting increased flooding and associated costs, and calculating the long- term benefits and costs of implementing green infrastructure. WERF https://www.werf.org Economic Evaluations of Stormwater BMPs https://www.werf.org/liveablecommun ities/toolbox/economic.htm Provides information on evaluating stormwater BMPs for cost-effectiveness and gained economic benefits. Port of Portland https://www2.portof portland.com/ Port of Portland Stormwater Standards Design Manual https://popcdn.azureedge.net/pdfs/ Stormwater_Design_Standards_Manual .pdf Describes several BMPs that can be used to meet water quality and flow control requirements. It also discusses the BMPs’ functions and benefits and provides a BMP selection process to determine which BMP would be most beneficial, depending on site and project conditions. Table 7. Example resources for developing values for project benefits.

30 Benefit–Cost Analyses Guidebook for Airport Stormwater 4.4 Financial, Environmental, and Social Benefits and Approaches to Assigning Value To the extent possible, an airport should assign values to anticipated benefits so that they can be incorporated into the BCA. Airports may identify benefits based on their own experience, research, or resources such as those identified in this guidance (see the References and Addi- tional Resources section). More specifics on calculation methods and alternative approaches for assigning values may be found in Appendix A and Appendix F. Tables 8, 9, and 10 show example financial, environmental, and social benefits that may apply to stormwater infrastructure proj- ects along with suggested approaches for assigning values to those benefits. Table 8. Example financial/economic benefits and suggested approaches to assigning value. Category Element Example Approaches to Assigning Value Avoided costs Water for non-potable uses (i.e., harvesting) Number of avoided gallons × 1,000-gal price. Avoided costs Energy (e.g., cooling provided by green roofs) Reduction in load (modeled or actual MMbtu or kW-h reduction × price). Avoided costs Replacement/repair of other components of stormwater system Estimated capital costs for design and construction. Avoided costs Damage to airport facilities from flooding and anticipated closure Estimated labor, material, and other costs from responses to prior events. Estimated number of flights delayed or cancelled because of damage and lost revenue per passenger or flight. Lost revenue associated with closure of concessions and tenants. Avoided costs Stormwater fees Reduction in impervious area or credits received for using GSI. Avoided costs Service disruption or cost of keeping service from being disrupted Costs associated with interruptions in airport operations while project is under construction or undergoing major maintenance. Suggested approaches: lost rent if terminals or other areas are shut down, reduction in enplanements due to construction × average revenue per enplanement. Avoided risks Fines for permit noncompliance Total fines: estimates per year from historical data, if applicable. Detailed estimate: historical legal/staff costs, levelized per year/% of stormwater managed by BMP × years useful life of BMP. Avoided risks Lawsuits from water quality and environmental advocates Historical legal/staff costs (or estimate provided by law firm), levelized per year/% of stormwater managed by BMP × years useful life of BMP.

Benefits 31 (continued on next page) Table 8. (Continued). Category Element Example Approaches to Assigning Value Avoided risks Replacement/resizing of stormwater infrastructure due to changing climate conditions Average capital cost of stormwater BMP normalized to standard size, then prorated to actual size + cost of resizing or replacing divided by expected useful life. Other Revenue from future expansion that is facilitated by extra drainage capacity Estimated number of enplanements with future expansion × estimated revenue per enplanement. Estimated revenue from tenant lease agreements. Category Element Example Approaches to Assigning Value Site-based performance Reduction in peak flow Engineers’ estimates, general information from literature, or anticipated performance based on modeling of stormwater system (e.g., SWMM). Suggested values: cubic feet per second (CFS) or other units of volume. Site-based performance Reduction in total site runoff Same potential information sources as total runoff. Suggested values: CFS or other units of volume. Site-based performance Pollutant removal Rough estimates based on literature values for typical. BMP removal efficiencies similar for projects and settings. May be based on stormwater system modeling (e.g., SWMM). Suggested values: percentage removal of pollutant from runoff by the project for design storm; estimated pollutant concentrations in runoff discharged from BMP. Other Reduction of harmful effects of runoff on receiving waters Anticipated reduction in streambank erosion and sedimentation. Suggested values: reduction in frequency of streambank rehabilitation activities, improvements in aquatic biota (e.g., species counts), or qualitative scoring based on professional experience. Sustainability Use of recycled materials in construction Example uses: imported soil from compost, use of cement replacement (e.g., slag or fly ash, or filter media made from waste or recycled materials such as wood chips or compost). Suggested values: “yes” or “no,” number of types of materials used, dollar value of materials used. Sustainability Support of airport sustainability planning and goals Suggested values: number of applicable goals or requirements addressed. Table 9. Example environmental benefits and suggested approaches to assigning value.

32 Benefit–Cost Analyses Guidebook for Airport Stormwater 4.5 Bayside Airport’s Benefits BAY’s team researched each benefit to assign monetary values to as many as possible. The team began by analyzing data that were readily available to the airport, such as capital and O&M costs associated with past projects, historic meteorological data, permit noncompliance fines, and historic use of potable water at the airport. To better understand the potential out- comes of the project options, the team contacted Oceanside Airport (OSD), another airport in the region that has implemented stormwater projects with elements similar to those in Options 2 and 3. OSD was able to provide BAY’s team with information on up-front capital and maintenance costs for the first few years of the infrastructure’s life (to be used later in the team’s assessment of costs). OSD also provided insight regarding potential benefits and drawbacks to the projects. Sustainability Compostable or reusable consumables Suggested values: percent of filter media, sand, or soil that can be reused or blended with other materials to make a safe, usable soil product. Sustainability Recyclable Suggested values: percent of facility or number or mass of disposable elements that can be recycled locally or conveniently. Sustainability Improvements in aquatic and riparian habitats Impact of value of healthy aquatic and riparian habitats. Suggested values: household willingness to pay, acres of wetlands improved or created, associated value of wetland services. Site-based performance Groundwater replenishment For infiltration-based stormwater BMPs, may be based on general estimates of typical BMP performance or more detailed stormwater system modeling. Suggested values: volume (cubic ft, gallons) of water expected to infiltrate annually. Sustainability Support of municipal, county, or state sustainability planning and goals Suggested values: number of applicable goals or requirements addressed. Vegetation and landscaping Use of native vegetation Intrinsic value of native plants. Suggested values: “yes” or “no,” sq ft or acres covered by the vegetation, number of plant species, number of plants. Vegetation and landscaping Expected life of vegetation before replacement Consider climate change and future regimes. Suggested values: number of years, percentage of project life. Vegetation and landscaping Use of vegetation that does not promote wildlife hazards Suggested values: “yes” or “no,” sq ft or acres covered by the vegetation, number of species of plants, number of plants. Site-based performance Decreased impervious area Compare impervious area for airport or part of airport for each alternative or relative to pre-project. Suggested units: sq ft, acres, hectares, sq km. Category Element Example Approaches to Assigning Value Table 9. (Continued).

Benefits 33 Category Element Example Approaches to Assigning Value Safety Reduction of wildlife hazard risks Suggested values: “yes” or “no” to vegetation that reduces wildlife risks. Jobs Regional materials vendors Suggested values: number and percent of project dollars spent on local and regional materials vendors. Jobs Regional contractors Suggested values: local – FTE years as percentage of total project FTE years, number and percentage of total project dollars that can be set aside for disadvantaged, minority-owned, woman-owned, and emerging small businesses (normalized for construction and permanent). Cultural Aesthetic quality of BMPs (e.g., vegetated swales, bioretention cells, planter filter boxes) on airside Art through landscape design, species selection, and pruning. Suggested values: percent of outside public spaces included in the BMPs, number of BMPs with aesthetic design. Cultural Education Opportunity to educate and show leadership on water quality management. Example: number of BMPs with interpretive signage, number of engagements with local environmental groups, web site or social media contacts with public over project. Other Improving permitting process for airport and others Familiarizing local permitting authorities with innovative stormwater BMP designs. Suggested values: anticipated cost savings due to more efficient and faster permitting , potential reduction in staff FTE × labor rates. Other Effects on local industries Effects of improved water quality on commercial fishing, aquaculture, or recreational fishing in affected receiving waters. Suggested values: percent contribution of airport runoff to pollutant loadings in receiving waters × anticipated improvement in water quality from project (environmental benefits for reduced runoff volume and pollutant removal). Table 10. Example social benefits and suggested approaches to assigning value.

34 Benefit–Cost Analyses Guidebook for Airport Stormwater The team also contacted a local university, which had an environmental department with experience in monetizing benefits of regional environmental resources. The university directed the team to recent research on recreational benefits of coastal areas and helped it interpret the research in the context of the BAY’s analysis. Finally, BAY’s team contacted Bayside City’s Department of Parks and Recreation for information on beach maintenance requirements near the airport’s existing stormwater outfall pipe, which discharges stormwater into a small stream that empties to the beach. Table 11 summarizes the final values identified by BAY’s team through its research efforts. Recognizing that annual and periodic costs could fluctuate from year to year, the team ensured that the annual or periodic benefits selected for the analysis represented reasonable average values per year (or per specified period). Table 11 also identifies the sources the team used and describes how the team calculated the benefits using the resources available to it. As noted in the table, the team was unable to identify readily available monetary estimates for most benefits. The team will use qualitative analyses to incorporate those benefits into the BCA. Table 11. Final values for benefits. Benefit Value Source and Notes Achieves permit compliance and avoids fines Option 1: $0 Option 2: $188,000 every 10 years Option 3: $281,000 every 10 years Source: History of BAY’s fines for permit noncompliance. Notes: Based on the design capacity of the infrastructure under each option, BAY’s team estimated that the airport would incur permit fines under Option 1 every 10 years, but that most of these fines would be avoided under Options 2 and 3 with the capture/reuse component. Option 3 would avoid additional fines as a result of the bioretention cells. Avoids standing water 48 hours following rain Qualitative Source: N/A. Notes: BAY’s team determined that, as a minimum requirement, all three options would drain standing water within 48 hours of rain to avoid attracting wildlife. The team was unable to easily identify monetary avoided costs, so this outcome will be incorporated as a qualitative benefit to recognize that this important aspect was considered. Improves water quality in bay (above permit compliance) Qualitative Source: Engineers’ estimates of effectiveness of each option in removing contaminants of concern (total suspended solids, nutrients, pathogens, metals, and organics). Note: No monetary estimates were readily available. The airport will address this in the qualitative analysis. Frees up land surface for other use All options: $300,000 one-time benefit in year 10 of the analysis Source: The city’s estimate of the value of 0.3 acres (equivalent to the size of the subsurface detention system). Note: All options include a subsurface detention system that frees up the land surface for other uses. BAY has few areas of undeveloped space on its property. BAY’s team considered the price of land around the airport as a proxy for the value of the 0.3 acres and estimated that the airport would benefit from having this open space in 10 years. Avoids cost of expanding stormwater collection infrastructure Option 1: $0 Option 2: $0 Option 3: $181,000 capital cost Source: History of BAY’s costs for developing stormwater collection infrastructure. Note: By installing bioretention cells that promote infiltration, Option 3 will reduce costs associated with the piping that would be needed for conventional, conveyance-based BMPs.

Benefits 35 Table 11. (Continued). (continued on next page) Benefit Value Source and Notes Expedites permit process resulting from good will Option 1: $0 Option 2: $1.3 million Option 3: $1.3 million Source: BAY’s engineers’ estimate of cost escalation and estimates of revenue loss if project is delayed by 1 year. Note: BAY works closely with the permitting agency to address water quantity and quality concerns. BAY understands from experience that projects move much more quickly through the permitting process if the plans demonstrate that the airport will exceed permit requirements. Based on the airport’s own knowledge of the permitting process, and based on the engineers’ estimate of cost escalation and lost revenue, BAY’s team estimated the potential benefits from an expedited permit process under Options 2 and 3. Because of the uncertainty surrounding this estimate, BAY’s team flagged this benefit for further evaluation in the sensitivity analysis (to be conducted at the end of the analysis). Reduces costs associated with annual stormwater monitoring program Option 1: $0 Option 2: $142,000 annually Option 3: $213,000 annually Source: History of BAY’s stormwater monitoring costs and estimates from OSD on reduced need for monitoring. Note: OSD indicated that its capture and reuse infrastructure has reduced its stormwater monitoring costs because it is not required to perform monitoring when there is no discharge to the ocean. The BAY team used OSD’s results as a proxy for expected changes to its own stormwater management program. BAY has an intensive stormwater management program due to its strict permitting requirements and proximity to the bay. Improves conditions on the beach and bay for recreation Option 1: $0 Option 2: $199,000 annually Option 3: $199,000 annually Source: University analysis on value of beach recreation, Bayside Beach closure policy, and beach attendance estimates. Note: Bayside Beach recommends no swimming 72 hours after rainfall exceeding 0.2 in. due to discharge of stormwater runoff. Water quality during this period is poor, poses a health risk, and deters swimmers. BAY is one of a number of contributors to water quality issues, and BAY’s team estimates that Option 1 would further contaminate the water. The team worked with the local university to understand the approximate nonmarket value of a single visit to Bayside Beach. The university provided a range of values based on prior research efforts. BAY’s team used the lower-bound value as the basis of the value of a single visit to the beach. Using beach visitation records and historic beach closure records, the team estimated the potential loss in beach recreation under Option 1. Because BAY is only responsible for a portion of stormwater pollution in the bay, and because Option 1 would add to an existing problem, the analysis team used 10% of the estimated loss in beach recreation. This value was incorporated as an avoided cost under Options 2 and 3. Because of the uncertainty surrounding these estimates, BAY’s team flagged this benefit for further evaluation in the sensitivity analysis (to be conducted at the end of the analysis).

36 Benefit–Cost Analyses Guidebook for Airport Stormwater Table 11. (Continued). Benefit Value Source and Notes Reduces costs associated with stream and beach erosion through peak-flow attenuation Option 1: $10,000 every 10 years Option 2: $20,000 every 10 years Option 3: $15,000 every 10 years Source: History of Bayside City’s Department of Parks and Recreation beach repair costs and peak-flow estimates from BAY engineers. Note: BAY’s existing outfall pipe is located on the sandy beach. Intense storms have caused high peak flow through this discharge point, causing long-term erosion. The city has periodically repaired the area around the pipe, and BAY’s team estimates that Options 2 and 3 would avoid additional erosion at the outfall and would reduce the potential frequency of repairs needed by the city. Reduces need for potable water Option 1: $0 Option 2: $102,000 annually Option 3: $102,000 annually Source: BAY’s water-use records, meteorological data, and water rates. Note: BAY’s team estimated average annual rainfall to determine what volume of water would be available for non- potable reuse. Using BAY’s water rates, the team estimated the avoided cost of purchasing potable water.

Next: Chapter 5 - Costs »
Benefit–Cost Analyses Guidebook for Airport Stormwater Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

Many airports undertake stormwater projects to accommodate facility expansion, address obsolescence, and respond to evolving regulatory requirements. Often, stormwater infrastructure is installed or upgraded on a project-by-project and piecemeal basis, resulting in mismatches of sizes, material types, ages, and conditions.

When airports are considering expanding or improving their stormwater facilities, the immediate need for stormwater infrastructure modification may not be clear, and a benefit–cost analysis (BCA) is needed.

The TRB Airport Cooperative Research Program's ACRP Research Report 208: Benefit–Cost Analyses Guidebook for Airport Stormwater provides guidance on using BCAs to identify, evaluate, and select airport stormwater management projects. The guidance focuses on a triple bottom line approach that considers an airport’s finances and environmental and societal impacts. The guidance will be particularly helpful for small airports that may not have BCA expertise or experience with innovative stormwater projects.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!