Green Stormwater Infrastructure - Volume 2: Guidebook (2017)

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.

60 This section will guide airport managers through a careful evaluation of the BMPs of inter- est as they use all relevant information to conduct discussions with other airport staff as well as external stakeholders. In this final section, guiding questions are provided for airport managers to use when considering GSI implementation. In addition, a hypothetical example of GA airport staff using these guiding questions is provided. With the facility- and region-specific information compiled and reviewed, and an understand- ing of the characteristics of GSI BMPs, airport staff can evaluate the feasibility of implementing GSI. This evaluation will encompass several aspects of decision making and may require consulta- tion with various departments at the airport as well as with engineers with GSI experience or other professionals (e.g., wildlife experts). The basic concepts of implementing GSI BMPs are similar to those of other environmental or sustainability programs at airports. For any program to be successful, it is important to involve management, tenants, and all other interested stakeholders during this step and throughout the process. Stakeholders in the process may include representatives of: • Airport management, finance, and maintenance; • Tenants and leaseholders; • Members of the community such as business and civic organizations; • Local and state officials; and • State and federal permitting agencies. The GSI feasibility evaluation will facilitate the airport’s implementation efforts. A care- fully crafted and targeted implementation strategy can increase the implementation success of the GSI BMPs. Each airport will have a unique implementation strategy. Implementation strategies, much like the programs themselves, will vary based on the environmental condi- tions at each airport, the size of the airport, available resources, and the needs and prefer- ences of stakeholders. As with other sustainability planning efforts, a successful strategy includes: • Engaging stakeholders to select, prioritize, and plan for short-term and long-term goals; • Ensuring adequate resources are available; and • Making the implementation schedule, which is the linchpin of the strategy. The implementation strategy should also identify connections between the airport’s GSI BMPs and other local, regional, and national stormwater management efforts, which will yield greater stakeholder support. S t e p 5 Evaluating GSI Feasibility for Airports

evaluating GSI Feasibility for Airports 61 Introductory Information for Stakeholders When beginning discussions with airport department and staff who are not familiar with the proposed project, airport managers may find brief introductory materials (e.g., a fact sheet or presentation) will help to orient them on the goals of the proposed GSI project. Examples of suggested content are as follows: • Where on the airport is GSI implementation being considered. • Types of GSI BMP under consideration. • Whether this is a stand-alone project or if it is being incorporated as part of a larger infra- structure project. • The airport’s primary stormwater management concerns. – Pollutants of concern for the airport. – Aspects of the airport’s stormwater management that are not performing optimally in terms of flood control. – Aspects of the airport’s stormwater management that are performing well in terms of flood control. • Types of stormwater issues the airport is addressing with the proposed project. • Initial cost estimates. • Current status of project considerations and decision making. • Input or information the airport is seeking to get from colleagues/stakeholders. Categories of Questions to Consider Questions to consider in discussions to evaluate the feasibility of implementing GSI fall into four categories: (1) overall facility planning, (2) BMP design and performance, (3) capital and O&M costs, and (4) management of wildlife hazards (Figure 23). By using the questions associated with each category in the context of the information gathered in the earlier sections of this guidebook, airport managers can conduct the appropriate discussions among their staff and other stakeholders. To highlight how to use the questions and gathered information to evaluate possible GSI projects, an example airport scenario is provided. In the following subsections, an explanation of Category 1: Facility Planning Category 2: Design and Performance Category 3 Capital and O&M Costs Category 4: Wildlife Hazard Management GSI Implementation Figure 23. Four categories to consider in GSI implementation.

62 Green Stormwater Infrastructure the category, including which stakeholders to have discussions with, is followed by a narrative of the example airport’s evaluation and a question table containing the example airport’s answers. Blank copies of the question tables can be found in Appendix B. Background information on the example airport scenario follows. Choosing potential GSI BMPs and deciding whether to implement them is airport specific, and the outcomes will vary among airports. This example will show how airport staff can use the guiding questions in this step to support decision making for implementing the appropriate GSI approach at their airport. Example Scenario: City General Aviation Airport Airport Characteristics City General Aviation Airport is a GA airport located several miles outside a large urban area in the Northeast United States. It is situated on a peninsula surrounded by two rivers that discharge into a large estuary. The airport serves as a reliever airport for the major commercial airport located in the nearby city and has fewer than 2,500 scheduled passengers per year. It also serves as a base for local news helicopters, medical transport services, and police aircraft. The airport property is approximately 650 acres (of which one-third is impervious). Approximately 66,000 takeoffs and landings occur per year at City General Aviation Airport. The airport has a single 5,500-foot-long runway and a helicopter landing pad. Potential Project The airport’s terminal is long overdue for a renovation. As a result, the airport is planning to ren- ovate and expand its terminal and parking lot to attract additional vendors and business. The town also hopes the expansion will attract and encourage more tourism in the area. Part of the planning for this project has entailed an evaluation of its potential effects on stormwater management. City General Aviation Airport particularly needs to consider the increase in volume of airport runoff due to increased impervious area. In addition, water quality of site runoff is a consideration, given the airport’s location near the estuary and the region’s ongoing efforts to curb nutrient loadings to the estuary. City General Aviation Airport’s existing stormwater management currently includes conventional retention/detention basins with outfalls that drain to one of the rivers surrounding the airport property. A portion of the stormwater runoff is directed to a municipal storm sewer system. City General Aviation Airport is exploring options to not only handle the additional site runoff anticipated but also to minimize site runoff from across the airport. Because City General Aviation Airport is essentially surrounded by an estuary, there are strict water quality regulations in place. First of all, the airport must comply with limitations on volume and certain pollutants (including nutrients) specified in its NPDES permit. The county in which the City General Aviation Airport is located also recently instituted a stormwater fee in an effort to reduce nutrient and sediment loading to the estuary. The fee is calculated based on the total square footage of impervious area, or ground cover that does not absorb water. The airport is subject to this fee, which is likely to increase with the terminal and parking lot expansion. The airport could potentially receive some financial relief if credits are received for the installation of GSI BMPs. GSI BMPs to be Evaluated To offset the expansion of the terminal and associated increase in impervious surface, the airport staff used Steps 1 through 4 to help them develop two potential GSI projects. They used the screen- ing matrices in Step 3 and the BMP information in Step 4 to identify and learn about BMPs that might suit the needs of their airport. Several BMPs such as green roofs, permeable pavement, and infiltration trenches were eliminated based on factors such as capital costs, compatibility with their maintenance capabilities, and other site-specific characteristics and concerns. The airport staff

evaluating GSI Feasibility for Airports 63 decided that bioswales and bioretention cells were likely to fit in well with their facility’s layout and land uses and would also be aesthetically pleasing. The following are the two options considered: 1. Bioretention cells throughout the parking lot (Figure 24a). 2. Bioretention cells throughout the parking lot in addition to bioswales along the sides of the renovated/expanded terminal building and along a portion of the runway (Figure 24b). To further weigh the merits and feasibility of these two options and move toward a final deci- sion, the staff at City General Aviation Airport used the guidance and question sets in Step 5. Category 1: Coordination with Overall Facility and Regional Planning and Stormwater Management Placing the proposed GSI in the context of overall facility planning during discussions with both internal and external stakeholders can have several benefits: • It may help spur additional ideas about areas where GSI might be placed. • It may be more cost and labor efficient to incorporate GSI into a larger infrastructure project than to implement it as a separate project. a. Option 1: Bioretention b. Option 2: Bioretention and Bioswales Figure 24. Terminal and parking lot expansion and renovation plans with green stormwater infrastructure for City General Aviation Airport.

64 Green Stormwater Infrastructure • It may help initiate discussions about GSI that may benefit longer-term planning by prompt- ing consideration of GSI strategies when future opportunities arise. Incorporating GSI into Facility Improvements and Planning More often than not, stormwater management practices are implemented in conjunction with some larger capital improvement plan. For example, Denver International Airport recently opened a new airport hotel, and a stormwater detention pond (a conventional stormwater BMP) was constructed along with it. Similarly, Los Angeles International Airport decided to incorporate a series of bioswales along the taxiway as part of a project to relocate the southernmost runway. San Diego International Airport has incorporated several GSI BMPs into larger airport projects: Bioswales and permeable pavers were included in the Green Build Expansion Project (2010–2013) and four large bioswales were con- structed as part of the new rental car center (2016). Currently, San Diego Inter- national Airport is looking into integrating rainwater capture and reuse into the design of a new parking plaza. Other airports are becoming interested in pursuing GSI, as described in their airport sustainability plans. Newark Liberty International Airport’s Sustainable Manage- ment Plan (2012) includes the objectives to “analyze all stormwater management options for new projects, including maximization of pervious surfaces,” and evalu- ate options for stormwater capture and reuse. As a potential sustainability initia- tive, Hartsfield–Jackson Atlanta International Airport plans to implement sustain- able stormwater management design for all buildings, according to its Sustainable Management Plan (2011). Evaluation for stormwater management and LEED design is particularly emphasized for new construction and renovation projects. Clarity on how GSI will serve larger organizational, regional sustainability goals may also help when interacting with stakeholders with environmental interests and concerns. Coordinate discussions with: Planning and engineering staff Environmental permitting staff Business management staff External stakeholders The following City General Aviation Airport example and guide questions will help in evalu- ating and discussing GSI in the context of overall facility and regional planning. Example Scenario: Category 1: Facility Planning and Stormwater Management Because the reduction of volume and nutrients in airport runoff and compliance with its NPDES permit requirements are important concerns for the airport, stormwater management has been included as a focus area in City General Aviation Airport’s sustainability management plan. Spe- cifically, the plan calls for City General Aviation Airport to consider the implementation of GSI not only as a supporting element of capital improvement projects for new airport facilities but also as the primary element of stand-alone stormwater management projects (apart from an associated structure or facility). In this case, City General Aviation Airport is considering GSI to mitigate the anticipated effects of the terminal and parking lot expansion on airport runoff and to take advan- tage of the opportunity to improve its overall stormwater management at the airport.

Guiding questions for Category 1 with scenario answers. Questions Airport Answers How would implementation of GSI fit in with the overall planning goals of your facility, municipality, and region/state? Sustainability management plan, facility planning, stormwater remediation fees . Would the GSI strategies under consideration be consistent with your facility’s master plan, sustainability plans, and/or stormwater management plans? Yes. GSI would be installed with the planned terminal and parking lot expansion in our facility’s master plan. The master plan also calls for continued maintenance and improvement of site stormwater management. This project would fit into our sustainability plan, as the plan promotes GSI. The BMPs in the project are among several listed in the sustainability plan for consideration. The plan also calls for reducing runoff from our facility and reducing our overall impact on the estuary. How would the GSI strategies under consideration mesh with municipal, regional, and/or state environmental and sustainability goals and plans? We’ve been reviewing the water quality goals for the estuary and rivers laid out by the Riverkeeper NGO, the Interstate River Basin Commission , and the state’s Department of Environmental Quality. Regional goals include controlling inputs of nutrients and other pollutants into the estuary so that the surrounding rivers and the estuary will maintain water quality for their designated uses . For stormwater fees, we’re currently paying $22,500 per year based on our current impervious footprint of 190 acres. If impervious surface is reduced by implementing a GSI BMP, then the fee would be reduced and pollution would also be reduced. How would the proposed BMPs increase climate resilience? When the time comes to finalize BMP designs for flow control features , we will work with the consulting engineer to include a margin in th e design storm to accommodate potential future increases in the number of large storm events. How would your proposed stormwater project fit in with proposed or ongoing infrastructure projects? Terminal renovation and expansio n. Would this be a retrofit or new BMPs incorporated into a larger infrastructure project? New BMPs incorporated as part of larger infrastructure project. If there are larger infrastructure projects ongoing or planned, what parts of the airport will be affected and what are the possible effects on your facility’s stormwater management? The target time frame for completion of the renovation and expansion of the terminal and parking lot is late 2017/early 2018. Due to the expansion, the facility impervious area will increase by an estimated 10 acres, or 435,600 square feet. We will need to manage runoff from the larger terminal building and parking lot and would like to also build in some additional capacity for management of runoff from the airside if possible. How would GSI help with stormwater management? The GSI would help compensate for the increase in impervious area from the expansion, by (1) reducing the overall site runoff, which, in turn, will reduce pollutant loads to the estuary, and (2) reducing the peak runoff rate that flows into the rivers feeding the estuary. It is also expected to reduce the hydraulic load on existing storm sewers. (continued on next page)

66 Green Stormwater Infrastructure Questions Airport Answers How would your proposed stormwater project fit in with existing or planned conventional stormwater BMPs? Existing BMPs: retention/detention basins How will your proposed GSI BMPs work in concert with your existing stormwater management program (e.g., will your GSI connect to or enhance the performance of existing conventional stormwater BMPs)? The existing detention basin on the southwest side will still be in use, but the GSI BMPs will infiltrate runoff closer to the source, reducing the amount that is directed to the detention basin. The GSI should also reduce the amount of runoff going to the MS4 drains on the east side of the facility. Will GSI BMPs be connected to other types of BMPs (e.g., filter strip in front of a retention pond)? Option 1 (bioretention in the parking lot) will not be connected to other conventional or GSI BMPs. In Option 2 (bioretention in parking lot plus bioswales along sides of building and part of runway), the bioswales should infiltrate runoff from the terminal building and tarmac for smaller storms and probably most of the runoff for medium size storms (to confirm with engineers about sizing if we decide to do the bioswales). For larger storms, the bioswales will infiltrate but would also convey excess runoff to existing storm sewers (to confirm with engineers). Will your GSI BMP be installed along with new conventional BMPs (e.g., retention ponds)? No. No new conventional stormwater BMPs are planned at this time. What other external stakeholders will you need to include in the decision-making process and what information will they need? We will be talking to the Riverkeeper NGO, the Interstate River Basin Commission, and the state Department of Environmental Quality to get their input on local water quality concerns associated with runoff. We have scheduled a meeting with FAA representatives to make sure both of our options would comply with all app licable FAA regulations, especially pertaining to wildlife management. We’ll be developing a 20-minute presentation and a 2-page fact sheet with diagrams to explain the project. When our engineers have completed their runoff estimates (with and without the GSI project), we’ll provide those to stakeholders. We’ll also make our engineers’ report available to stakeholders for review. Category 2: GSI BMP Design and Performance: Water Quality (Pollutant Removal) and Quantity (Runoff Peak Flow and Total Volume) In deciding whether to adopt GSI, airports will want to evaluate the feasibility of GSI practices they are considering in terms of stormwater management needs, site constraints, and BMP characteristics. After using the screening matrices in Step 3 and learning more specifics about BMPs of interest under Step 4, users may want to read suggested resources (e.g., reports, websites, and GSI guidance) for more details about BMP performance and the experiences of other airports or municipalities. It may also be beneficial at this point to talk to

evaluating GSI Feasibility for Airports 67 professionals at other airports or municipalities who have implemented GSI to ask questions or to learn about their experiences with GSI in general. Coordinate discussions with: Planning and engineering staff Environmental permitting staff Facilities and infrastructure staff The following City General Aviation Airport example and guide questions will help in prompt- ing discussions among internal stakeholders or outside professionals. Example Scenario: Category 2: GSI BMP Design and Performance When considering the appropriate stormwater management infrastructure for this project, the airport evaluated several BMPs. Infiltration basins and trenches were ruled out because of a seasonally high ground water table. The options were narrowed down to bioswales, a proprietary media filtration system, or bioretention. City General Aviation Airport saw bioretention cells as fitting into the new and expanded parking lot (Option 1). The cells would be able to capture the runoff from the increased impervious area of the parking lot. City General Aviation Airport saw additional benefit in also including bio- swales (Option 2), which would be placed along the sides of the new terminal building and along part of the runway. Although Option 2 would greatly reduce runoff volume, it would require larger initial costs compared to Option 1. Table 9 summarizes the two options under consideration. Option GSI BMP Location Purpose Benefits Cost for Installation 1 Bioretention cells Parking lot for terminal Capture runoff from parking area 1. Reduced stormwater fees 2. Compliance with NPDES permit standards Requires relatively low initial capital investment 2 Bioretention cells and bioswales Parking, for terminal, around sides of terminal building, airside Capture runoff from parking area, from terminal roof, and a portion of the runoff from tarmac/apron Same as above but greater overall benefit Requires somewhat higher initial capital investment Table 9. GSI BMP(s) options. Questions Airport Answers What are your proposed GSI BMP options? We are considering two options: 1. One BMP type: Bioretention cells in the terminal parking lot. 2. Two BMP types: Bioretention cells in the terminal parking lot and long bioswales on the sides of the terminal build ing area wrapping around toward the ends of the tarmac/apron on airside (see diagram). (continued on next page) Guiding questions for Category 2 with scenario answers.

68 Green Stormwater Infrastructure Questions Airport Answers Have you confirmed this through consultation with additional sources or through communication with GSI professionals? Yes. We have spoken to stormwater engineers, experts at our associated Large Commercial Airport, and professionals from other nearby airports (GA and commercial). Our Large Commercial Airport has had good luck with bioretention cells landside near their terminal building and had a lot of advice on maintenance. What is known about how the GSI BMPs you are considering affect the management of your pollutants of concern? The bioswales could potentially assist in nutrient and sediment removal, issues of concern in the estuary. Is there space available for your BMPs at the airport, and are other factors, such as soil infiltration rates, adequate to manage your design storm? Although space is at a bit of a premium at our facility, we do have adequate space in the expanded parking lot, along the sides of the terminal building, and along the runway. Are there design parameters that may be adjusted (e.g., media selection, and decisions regarding vegetation) if adequate space is a concern? (This may involve discussion with stormwater engineers with experience in designing GSI BMPs.) We are considering long bioswales, with simple grassy vegetation closer to the airside for easy mowing and wildlife hazard management, and more variable vegetation for a more “landscaped” appearance closer to the front edge of the terminal building. We’ll be discussing vegetation options with engineers, loca l wildlife experts, and FAA staff, as well as using guidance documents on vegetation selection for the final decisions. How will you assess performance of GSI once it has been implemented (e.g., visual inspections for standing water, or routine monitoring associated with regulatory compliance)? Primarily by visual inspections for standing water near the terminal building and on the airside. Per our NPDES permit, we are collecting quarterly stormwater samples at two outfalls . How do you expect the GSI to help you maintain regulatory compliance (e.g., NPDES permits)? We anticipate that the GSI could reduce nutrient loading to the estuary. Once installed, we would confirm how much by comparing the NPDES monitoring results before and after installation of the GSI BMPs. Climate and Geography Are there climate, geographic, or other factors that will need to be considered in planning your GSI strategy (e.g., vegetation selection, soil permeability)? The area in which the airport is located experiences annual precipitation of approximately 40 inches, but the region is prone to storm events during July and August. Our engineering consultants will account for this when sizing the BMPs. Our soils are moderately permeable and should be able to allow for good infi ltration rates. Are there aspects of the site history to consider (e.g., compacted soils due to previous construction at the site)? No. Construction history at the site has been minimal. Our engineering consultants say they would watch for areas where t he soil has been compacted when they install the BMPs and work with us to address it. Are there particular GSI BMPs that you think would be inappropriate for your facility? Infiltration ba sins.

evaluating GSI Feasibility for Airports 69 Category 3: Capital and O&M Costs and Implementation The costs of implementing and maintaining GSI practices is a crucial component of evaluat- ing the feasibility of adopting GSI and will vary widely by facility and by the nature of the GSI project. Capital costs may be handled as part of the budget of a larger infrastructure project or may be formulated separately for a stand-alone project. Similarly, certain types of O&M expenses may be readily accommodated as part of normal airport operations, but for some BMP types, specific types of maintenance may be needed (e.g., sweeping and vacuuming permeable pavement). For broad estimates, airport staff can look at: • The general estimates provided in the BMP descriptions under Step 4, • The data provided by airports in the case studies (Appendix A), and • Other GSI-related resources such as the Center for Neighborhood Technology’s Green Values Stormwater Toolbox (http://greenvalues.cnt.org/). O&M Activities: Costs and Convenience A common misconception is that GSI is too expensive to implement and main- tain. Some airports that have implemented GSI BMPs expressed frustration with estimating costs and providing adequate justification for those estimates. How- ever, evidence has shown that costs can be manageable. San Diego International Airport costs for O&M are covered under the airport’s contract for landscaping. Austin–Bergstrom International Airport did not express concern over excessive O&M costs. Costs to maintain rain gardens at the airport so far have been similar to costs related to upkeep of flower beds at the airport. As learned from Seattle– Tacoma International Airport, O&M costs and activities can be minimized if O&M requirements are considered during the design process. For example, bird netting can be difficult to maintain, concrete-bottom basins are easy to maintain, and access to basins is difficult if access roads are not aligned correctly. O&M consid- eration in initial planning and designing of GSI BMPs can make O&M costs and activities more feasible in the long run. A more formal cost–benefit analysis may be warranted at some point during this process. Airport staff may also want to begin identifying stormwater engineering firms with experience installing GSI BMPs. Coordinate discussions with: Planning and engineering staff Operations staff Facilities and infrastructure staff Business management staff The following City General Aviation Airport example and guide questions will help frame discussions with internal stakeholders on the economic aspects of the proposed GSI project. Example Scenario: Category 3: Capital and O&M Costs Funding and available resources play an important part in the decision to implement GSI BMPs. City General Aviation Airport has established that Option 2 has greater initial cost than Option 1. On the other hand, Option 2 provides greater benefit in reducing runoff volume and could save the airport more money in the long run by reducing its stormwater fees. Regarding

70 Green Stormwater Infrastructure O&M costs, the airport anticipates that these costs will be minimal and can be subsumed under regular airport O&M costs and activities. Category 4: Management of Wildlife Hazards As a significant safety and regulatory consideration for stormwater management, handling of wildlife hazards will likely be an integral part of the discussions regarding design and overall fea- sibility. Airports, in concert with their own or external wildlife biologists, have adopted various strategies to manage wildlife hazards both with GSI and conventional stormwater BMPs. Airport staff may consider both established and innovative options to address this issue. Questions Airport Answers Will you be funding construction of your GSI as a stand-alone project or as part of a larger capital improvement project? Part of a larger capital improvement project. Have you identified potential funding sources? State grant or private funding. [Airport can add details on funding sources as needed.] How does the estimated cost of your GSI compare with available funds? The estimated cost of implementing Option 2 is roughly 20 percent more than the cost of implementing Option 1. The budget will allow for installation of at least Option 1 and possibly Option 2. Once estimates are further refined, we will know if we can afford both at this time. If not, we would include the bioswales in our longer-term capital planning. Has a cost–benefit analysis been done (or do you anticipate performing one) to include GSI? No, but we are considering performing one. How detailed are your cost estimates at this time? Range, ballpark, or more specific? Our cost estimates for BMP installation are currently based on costs for similar structures at municipal and commercial facilities within the state. These estimates are helping us get a ballpark idea of costs but will need to be refined for our facility. What other information will you need to obtain a more refined estimate or to begin requesting bids? We will need to finalize some costs for some remaining aspects of the terminal constructi on, after which we will have an updated estimate of funds available for GSI. We can then solicit initial bids from contractors for doing the GSI. How will O&M be handled for your GSI? See subsequent answers. Will O&M be done by airport staff or by contractors? Airport staff . Will O&M for your proposed GSI require specialized knowledge, or will it be similar to existing O&M (e.g., mowing and general landscaping)? Similar to existing O&M, including mowing and maintenance of landscaping. How can it be coordinated with existing O&M activities at your facility? Can be coordinated with general landscaping and mowing. What are the anticipated O&M costs for your GSI? O&M costs will fold easily into existing expenses. Operations staff say that these BMPs should cause zero to minimal increase in overall O&M costs. Guiding questions for Category 3.

evaluating GSI Feasibility for Airports 71 Coordinate discussions with: Planning and engineering staff Environmental permitting staff Wildlife management specialists The following City General Aviation Airport example and guide questions will help frame discussions on this topic. Scenario Example Category 4: Wildlife Hazard Management Preventing wildlife hazards is a priority at all airports. As a result, GSI BMPs must comply with FAA regulations regarding wildlife. During City General Aviation Airport’s evaluation of various BMPs, the airport identified BMPs that were least likely to attract wildlife. The two options under consideration would not create standing water and would be constructed with vegetation that does not attract wildlife. Guiding questions for Category 4. Questions Airport Answers What wildlife hazards (e.g., which species, migration patterns, nearby habitat) has your facility needed to manage? Various mammal and avian species. What wildlife hazard mitigation measures do you currently have in place? Landscape management to remove vegetation that attracts wildlife and to eliminate ponding and open water. Are you satisfied with the success of your wildlife hazard management? Yes. We have only 9 bird strikes per year, down from 12 in 2009, and below the national average of 19 strikes for every 100,000 flights. Would your existing wildlife hazard management measures apply to your proposed GSI? Yes – landscape management/mowing, minimize standing water. If not, have you consulted with wildlife management experts regarding possible solutions? N/A Have you learned of any new or innovative developments for wildlife hazard management? No, not at this time. How will your proposed wildlife hazard management plans enable you to comply with FAA regulations when you implement GSI? Since mowing and landscaping are already a part of our wildlife hazard management plan, these activities will be applied to the GSI BMP(s). We anticipate no problems maintaining compliance with FAA regulations. Next Steps After an initial round of information gathering, information sharing, and discussions with internal and possibly external stakeholders, airport staff may want to take stock, evaluate their current state of knowledge, and identify data gaps that need to be filled and concerns that need to be addressed before moving forward with plans. If there are no significant areas where more information is needed, the airport staff may be at a stage where they can begin their facility’s normal process of initiating an infrastructure project. The following City General Aviation Airport example and guide questions will help frame discussions about ongoing or final decision making regarding a GSI project.

72 Green Stormwater Infrastructure Scenario Example: Next Steps So far, City General Aviation Airport has decided that, at the very least, they plan on incorporat- ing bioretention systems into the expanded parking lot. However, the airport has not decided if they will go further and implement the additional GSI BMPs depicted in Option 2 at this time. Option 1 would provide a reduction in runoff from the parking area, which would count as a credit toward what the airport pays the local government in stormwater fees. Furthermore, Option 1 would provide regulatory benefit because the bioretention would help to maintain compliance with the NPDES permit. Option 2 would also provide these benefits in addition to capturing and treating runoff from the new terminal’s roof and partially from the runway on the airside. Option 2 would provide greater overall benefit over the long term but would require greater initial costs. If City General Aviation Airport is unable to fund Option 2, the airport will consider incorporating these additional GSI BMPs in the future, implementing one GSI BMP at a time. At this stage, City General Aviation Airport has weighed information in the four categories—facility planning and stormwater management; GSI BMP design and performance; costs, both capital and O&M; and wildlife hazard management. It will soon make its final decision as to whether to implement Option 1 or Option 2 as part of its plans to renovate and expand the terminal and parking lot. Questions Airport Answers For each of the four categories above (facility planning, design and performance, capital and O&M costs, and wildlife hazard management), what are the most challenging issues for your airport? 1. Stormwater fees. 2. Reducing airport runoff . 3. Calculating more precise cost estimates for GSI BMPs. 4. Maintaining good wildlife control. Are there remaining institutional or regulatory barriers? As long as we comply with FAA regulations, we see no regulatory barriers. What information gaps have emerged from your review and discussion? How can they be addressed? Our main information gaps at present are costs for the various components of the facility expansion and whether we will have funding to implement both the bioretention areas and the bioswales. This should resolve as we get refined bids for the terminal building construction. Are there additional airport staff you need to communicate with? No. We have coordinated among our fiscal, planning, engineering, and maintenance staff. Is there additional, outside input you need or want and have not yet solicited? We want to talk to more GSI experts to make sure we haven’t overlooked any potential costs or other issues. We have names of researchers with bioswale experience at a nearby university and the local municipal engineers who have overseen the GSI retrofitting downtown. Are you at the stage of coordination with federal, state, and local permitting authorities? We are still in the planning stages and deciding on the most appropriate GSI BMP option at this time . Are additional meetings with external stakeholders anticipated? Yes. If so, what questions and concerns do you expect from them and what information do you want to have on hand? Before we meet with external stakeholders, we plan to have more exact cost estimates. Guiding questions for the next steps for City General Aviation Airport.