Habitat Management to Deter Wildlife at Airports (2014)

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29 chapter eight WATER RESOURCES Water is an essential resource for all wildlife, and hence a major attractant even in seemingly small quantities. Wildlife will seek water not only for consumption, but for the edible plants and animals bodies of water contain. Areas of open water can also be a safe zone for birds such as ducks and geese that are more vulnerable to predators when on land. One of the greatest challenges facing airport designers and operators is controlling and removing stormwater/standing water from airport sur- faces. Local, state, and federal regulations often limit how wetlands can be altered or eliminated; and airport operators need to be prepared for a possibly complicated permitting process when attempting to remove a wetland area from their landscape (Cleary and Dickey 2010). Restricting access to open water resources, minimizing standing water in the AOA, and reducing the attractiveness of water bodies may all be necessary to minimize wildlife attraction to water resources on and around airports (Blackwell et al. 2013). WETLANDS AND MARSHES Wetlands and marshes are natural enticements to wildlife. Even small wetland areas can provide food, water, and sometimes shelter to potentially hazardous species such as geese, ducks, and wading birds. Removal of wetlands and marshes in the United States requires a federal permit from the U.S. Corps Water Resources: Logan International (BOS) Boston’s Logan Airport is nearly surrounded by water, much of which is shallow tidal marsh. These areas are extremely attractive to many types of wildlife, especially waterfowl, gulls, raptors, and shorebirds. In addition, many people frequent these areas, and can attract wild- life through intentional feeding or unintentional provision of food through exposure of natural food sources such as clams. Removing or mitigating this habitat is not possible, so other means of reducing wildlife-airstrike hazards must be used. Further, some of the species that use Logan property are considered threatened by the state of Massachusetts [e.g., upland sandpiper (Bartramia longicauda)] and protected from many habitat manipulations and removals. On-site mitigation of habitat may be one of the few options in such cases. Boston Logan is an example of why developing a wildlife hazard management plan is so important. The wildlife management staff at the Massachusetts Port Authority (Massport) has worked with local, state, and federal agencies to develop safe and effective methods of addressing a variety of wildlife hazard issues at a very busy airport. Its WHMP identifies potentially hazardous wildlife—seven mammal and 35 avian species—that use Logan property and surrounding areas, as well as the habitats they are attracted to. Understanding the source of potential hazards is key to reducing risk. The WHMP also includes standard methods for deterrence and control of wildlife, necessary equipment, required permits, personnel responsibilities, and contact information. Wildlife control staff patrols Logan property 16 hours each day, at an annual budgeted cost of $750,000. View of coastal Boston, MA area showing Logan International Airport (BOS) nearly surrounded by water (Source: NASA).

30 of Engineers as well as local and state permits; and may necessitate mitigation of removed wetlands on other property within the same watershed and maintenance of the newly constructed wetland for several years (Dolbeer 2013). The allure of wetlands and marshes can be lessened by reducing available food (e.g., fish, insects, vegetation) and shelter (e.g., tall vegetation) resources in accordance with regulations. LAKES AND PONDS Like wetlands and marshes, naturally occurring lakes and ponds can be very attractive to a variety of wildlife including waterfowl, wading birds, fish-eating raptors, and others. Lakes and ponds may also be protected by regulations similar to those for wetlands and marshes. In a study of lake systems, Suter (1994) linked abundance and richness of various bird populations to area, food availability, and shoreline vegetation complexity. RIVERS AND STREAMS While rivers and streams tend to attract wildlife in less density than lakes or ponds because of their linear shapes and constant flow, they can still serve as sources of food, water, and shelter. Just as many cities are located near rivers and streams, so too are many airports, which can increase possible Water Resources—Natural: Spirit of St. Louis (KSUS) In the late 1980s, the Spirit of St. Louis Airport began an 11-year plan and federal permitting process to mitigate wetlands and stormwater drainage on the south side of the airport, which had become an attractant for waterfowl and other wildlife. Shortly before completion of the $2.5-million stormwater detention and drainage system in 1999, KSUS developed a plan for incorporating the system into a revenue-generating golf course specifically designed to help the drainage and alleviate the tendency for waterfowl to gather. As part of the wetland mitigation project, the airport was required to establish an alternative, larger wetland off-site, to maintain it for five years, and then to turn it over to the state as a conservation area. KSUS purchased a parcel of more than 200 acres many miles away, and relocated each species of plant to the site. An 18-hole USGA golf course was constructed in place of the original wetlands, with a series of meandering ditches that could handle the runoff from the airport and drain within 48 hours. Special techniques were used to create the course to ensure another wildlife attractant was not created. The course has no water features on it (i.e., no lakes), and the well water used to irrigate the course is stored in a large, 220,000-gallon underground bladder system to prevent attracting more wildlife. The golf course is one of the largest land-leasing tenants at the airport, producing steady revenue now and for years to come. Its lease also requires the golf course to maintain the drainage ditches, and does not allow it to add any features that will attract wildlife. For example, geese are often drawn to turfgrass and the open water commonly found on golf courses (Ayers et al. 2010); but if drainage is contained underground and undesirable turf is selected, their attractions may be minimized. Aerial view of KSUS with wetland present left of AOA in the 1980s (left) replaced by specially drained and irrigated golf course (right) (Source: KSUS).

31 Water Resources—Lakes and Ponds: Orlando International (MCO) Abundant and productive aquatic habitats on airport property, including the AOA, attract many species of potentially hazardous birds, as well as alligators and otters, especially during naturally occurring fish kills (die-offs). Minimizing aquatic biomass through fish removals, sediment dredging, and aquatic plant removal lessens the severity and duration of these events, consequently reducing strike potential. At Orlando International, fish are removed through electrofishing; and sport fish are relocated to public waters in other parts of the city and state. Dredging is conducted by the airport’s maintenance department, using heavy equipment including dozers, hydraulic excavator, and long reach excavator, among others. Aquatic weed control is conducted by herbicide applications and grass carp. Initial investment for fish removal equipment was ~$15,000, and annual aquatic herbicide use is ~$270,000. These biotic removals are a part of the airport’s WHMP. State fish and game permits were required for scientific collection and grass carp introduction, and an aquatic applicator license was issued from the Florida Department of Agriculture. Clockwise: Osprey feeding on fish at MCO; removing fish using electrofishing; releasing grass carp (Ctenopharyngodon idella) for vegetation control; and dredging to reduce shallow-growing aquatic vegetation (Source: MCO).

32 conflicts with wildlife using these waterways (Figure 9). Streams commonly attract waterfowl and shorebirds, but often birds will remain over or near the water. Streams are protected by federal and state environmental regulations that may limit management strategies. Reducing the attractiveness of vegetation adjacent to streams may be an effective approach to reducing the attractiveness of streams themselves. STORMWATER IMPOUNDMENTS Aircraft safety is the number one concern at an airport, and FAA guidance on controlling stormwater aims to remove water from hard surfaces quickly (within 48 hours) to reduce risk to aircraft. However, stormwater can often be detained or retained to reduce erosion and allow settlement and management Water Resources—Lakes and Ponds: Linn State Technical College (1H3) The Missouri Department of Transportation (MODOT) uses funds from the FAA to initiate airport improvement projects in Missouri. Each airport must be identified by the FAA National Plan of Integrated Airport Systems, and MODOT is required to do a wildlife habitat assessment and mitigation plan. For example, MODOT has worked with Linn State Technical Col- lege in Linn on a plan to remove ponds adjacent to a small airport owned by the college that attract potentially hazardous water- fowl. While MODOT does not do the actual modifications itself, it uses funding from FAA grants to pay for the work, and helps plan and organize the projects. MODOT will often pro- vide such funding for installation of fencing to exclude wildlife from airport property as well. Pond adjacent to Linn State Technical College Airport (1H3) planned to be removed (Credit: MODOT). FIGURE 9 PDX is located along the Columbia River near the confluence with the Willamette River (Source: Port of Portland).

33 of potential pollutants, according to the U.S. Clean Water Act (FAA 2006) and various local and state regulations. Standing bodies of water are major lures to potentially hazardous wildlife, including ducks and geese. Human-made ponds and other detention and retention water control structures often require modifications, such as restrictive fencing, overhead wiring, sloped banks, or complete surface covers (e.g., netting or floating balls; Figure 10) to eliminate attraction of waterfowl and other wildlife (Blackwell et al. 2013). However, such remedies may require frequent maintenance or replacement to remain effective. Tenant facilities on property surrounding airports can be a potential hazard if wildlife are induced to enter or cross over the AOA. Birds flying toward or away from a tenant stormwater facility adja- cent to an airport can be serious hazards to aircraft safety. While the FAA (2007) recommends maintaining a five-mile buffer between the AOA and a wildlife attractant, this is often not the case. Airport officials may need to work with local officials to mitigate the risk of attracting wildlife across airport property. The appeal of these facilities can be reduced by using designs that limit the surface area and perimeter of the water, and reducing the vegetation and grass area that surrounds retention ponds that may attract geese (Blackwell et al. 2013; Fox 2013). PONDING Pavement Impermeable pavement can cause puddling after storm events, which may attract hazardous wildlife (e.g., gulls) to airport property including the AOA. Proper engineering and planning of imper- meable areas often includes creating sloping to allow stormwater to flow off pavement to well- drained areas. Depressions in pavement can allow puddling of water after storm events and may require repair to prevent attraction of hazardous wildlife. Earthworms often migrate to pavement FIGURE 10 Water retention pond at PDX before and after installation of floating cover (i.e., bird balls; Source: Port of Portland). An impervious membrane was installed to maintain a water depth of 5–6 ft.

34 Water Resources—Human-Made: Dallas/Fort Worth International (DFW) Airports are not extricable from their surroundings, and operations on nearby private property or leased property often present risks. Like many airports, DFW must work with surrounding industries that may affect the safety in its AOA, which in its case include drilling for natural gas. These operations require retention of water used during rock fracturing that contains other sub- stances regulated for environmental quality. These open surface waters also attract potentially hazardous wildlife, mostly birds and mammals. The operators of the drilling operations have cooperated with the airport, and taken several measures to reduce wildlife use, including fencing, use of impermeable substrates to reduce vegetation growth, installation of overhead cables, and construction of steep slopes and walls to prevent wading near or out of the ponds. These combined efforts have been effective at reducing use by most species of concern. While retention or detention of water may be necessary for stormwater and wastewater management, proper planning, design, and cooperation can reduce risks of attracting hazardous wildlife. after heavy storms that drive them from saturated soils onto hard surfaces, and may then also attract worm-eating birds. Porous pavement is an open-graded mix placed in a manner that results in a substantial space between rocks, producing a high volume of absorption or storage within the voids, and infiltration to subsoils (Tokunaga and Wan 1997). The pavement might be permeable concrete or asphalt, a manufactured systems such as interlocking brick, or a combination of sand and brick lattice. At airports, porous pavement is suitable for passenger parking areas or infrequently-used service Techniques to reduce use of retention ponds by wildlife can include installing overhead cables (top left), fencing and impermeable substrates (top right), and steep walls and banks (bottom left) (Source: DFW).

35 roads. Concerns with weight-bearing capacity (FAA 2009) generally preclude its use where aircraft are maneuvering or parking, such as runways, taxiways, and clearways. In cold weather climates, the use of porous pavement in areas where grit is applied for traction, such as on parking lots, can result in pore clogging, standing water, or icy conditions. Permeable Surfaces Some airports use permeable materials such as gravel or asphalt millings for road surfaces. However, these surfaces can become clogged with dirt or grit over time, resulting in reduced permeability. Proper planning, engineering, and maintenance of roads with permeable surfaces can reduce forma- tion of depressions that retain stormwater. SLOPE When rain falls on impervious surfaces, it forms a layer of water that flows and becomes deeper as it approaches the edge and meets an outlet or permeable surface. Not only can this create an entice- ment to hazardous wildlife, it can also produce hazardous conditions for moving vehicles and may delay water removal from surfaces where puddles are likely to form. To prevent these hazards, the FAA recommends slopes for effective flow of water from the crown of a paved surface to the edge where an open permeable surface is located to then further drain the water (FAA AC 150/5320-5C). The adjacent permeable area can also allow surface flows with adequate slope leading to a drainage control system. Slope is also an important aspect of ditches and water holding bodies. Some airport operators have reported that ditches with steeper slopes are less attractive to wildlife because they present greater difficulty of walking up and down the slopes, and reduced visibility for awareness of predators (Figure 11). This is similarly effective in retention and detention ponds which, if constructed with a Water Resources—Human-Made: Port of Portland (PDX) Access to all parts of airport property is important for effective and efficient wildlife management. Airport operators in parts of the world where rain is common may have trouble accessing saturated parts of the AOA. At PDX, operators were limited by the lack of roads across saturated areas of turfgrass in parts of the AOA, preventing them from reaching areas necessary for aviation wildlife hazing. Planners and engineers decided to use asphalt millings to build roads through these often saturated areas. Proper design allowed these roads to shed water and avert ponding, while allowing access to more of the AOA for aviation wildlife management. Installing roads out of asphalt millings with impervious membrane at PDX (left) allowed greater access to the AOA for wildlife management operations (right) (Source: Port of Portland).

36 steep hard edge above the water level, are difficult for wading birds to use for foraging; and hinder waterfowl in climbing out of the water (see previous case example). DRAINAGE Surface Materials Many airports are restricted as to the amount of impervious surface they have on their property, in an effort to reduce high-flow storm events washing nutrients, sediments, and pollutants into nearby waterways (AC 150/5300-13). Airport operators should therefore be creative and judicious about where impermeable surfaces are necessary and where they might instead use soil, turf, or other per- meable materials (DeVault et al. 2013). Each of these surface materials will create different potential attractants to various wildlife species. Some airports have had success in reusing the asphalt millings from resurfacing projects on runways for new roadways or to replace turf or vegetation that had been attracting potentially hazardous wildlife. To maximize drainage of surfaces, operators can consider soil type, slope, vegetation cover, etc. that will affect the rate of permeation or drainage of water (Fredlund et al. 1994). Drainage Systems Alternative control techniques are available for managing stormwater that may not require a deep standing body of surface water. Higgins and Liner (2007) describe subsurface flow wetlands (SSFW; Figure 12) as insulated, aerated, easy to operate, and relatively inexpensive compared to traditional ponding facilities. SSFW are areas where stormwater runoff is directed into vegetated areas of well-drained soil or gravel with a slight slope. These areas may be lined with an imperme- able liner to prevent chemicals in runoff from leaching into ground water. After biodegradation and sedimentation of the detained water, it may evaporate or flow out of the vegetated area on the down slope. And because SSFW are underground, they do not attract wildlife as a surface water facility would. However, SSFW facilities tend to be large, to allow quick infiltration of shallow areas, which can lead to problems in freezing conditions. An alternative that Higgins and Liner proposed was engineered wetlands—vegetated gravel beds that allow quick infiltration and insulation to prevent freezing. Additionally, the vegetation is expected to absorb nutrients and other pollutants from runoff. Additional drainage techniques include best management practices known as low impact devel- opment (Dietz 2007; Davis 2008; Dietz and Clausen 2008) or green infrastructure (Washington Department of Transportation 2009); Oregon Department of Environmental Quality 2011a). These FIGURE 11 Ditches with steep slopes are less attractive to many wildlife species (Credit: A. Johnson).

37 techniques focus on use of natural or manufactured systems that use infiltration, evaporation, and reuse of rainwater to remove or control stormwater. Some of the specific infiltration techniques include reducing impermeable surfaces and retaining natural areas that allow rainwater infiltration; and installing specially designed infiltration areas such as gardens, trenches, and porous pavement. Grass swales and filtration strips along impervious surfaces may also be alternatives to retention facilities. However, these more natural infiltration areas may attract wildlife if they harbor such attractants as insects, worms, and vegetation. An evaluation of airport drainage systems in North Carolina led to the replacement of most surface water ponds with filtration strips and vegetated areas. Barrels and cisterns can also be used to control stormwater, collecting water to be used later for washing, landscaping, etc., without allowing access by wildlife. Stormwater permits for airports now require incorporation of low-impact development and green infrastructure techniques (Oregon Department of Environmental Quality 2011b, ACRP 09-08). All drainage systems will require maintenance and eventual replacement. Sedimentary buildup or clogging require relatively routine maintenance, but eventual degradation of concrete and metal structures will lead to the need to replace systems if they are inadequate or fail to properly remove stormwater. FIGURE 12 Example of a subsurface flow wetland (SSFW; Credit: University of California). Water Resources—Drainage: North Carolina North Carolina has 72 publicly owned and operated airports across the state, each with a unique set of wildlife hazard issues. However, one common issue is stormwater retention and detention ponds near runways that attract waterfowl. Information from North Carolina airports suggested high use by Canada geese on and near airports in the state. As was described in the section on stormwater, open ponds or other forms of stormwater control devices are often required in construction projects. In 2011, the North Carolina Department of Transportation’s Division of Aviation, along with the stormwater permitting agency [North Carolina Department of Environment and Natural Resources-Division of Water Quality (DWQ)] and other state agency and university investigators began to examine the issue of stormwater devices attracting hazardous wildlife. Shortly after, a bill was passed ordering a formal investigation by DWQ of the stormwater management requirements for the state. This led to new legislation changing the require- ments for open surface stormwater retention or detention ponds, allowing alternative methods within five miles of an airport AOA, such as grassed buffers, shoulders, and grass swales. These areas are much less attractive to the target hazardous wildlife, especially resident Canada geese. This allowed a change in the DWQ best management practices and recommended stormwater management around airports. The permitting for the alternative methods will still be reviewed and issued by DWQ, but it now has a much more effective set of tools to address a common wildlife-hazards issue.

38 Water Resources—Drainage: North Carolina (Continued) Retention ponds near airports (left) can now be replaced by adequate infiltration areas (right) (Source: NCDOT).