Brian Barton
Road construction, maintenance, and use can generate a significant amount of pollution to our nation's waterways. Poor planning and construction of roads, highways, and bridges can result in the deposition of sediment that can smother aquatic habitats and clog waterways. Runoff pollution, or nonpoint source pollution, is created when chemicals, debris, fertilizers, automotive oils, debris from wearing parts, and litter are washed off roadways and bridges during rainstorms and carried as runoff to streams, rivers, lakes, and bays. This can be prevented by applying management measures and best management practices during the planning, construction, and operation and maintenance of highway systems.
| Characteristics | Values |
|---|---|
| Construction Site BMPs | Straw bale barriers, filter fabrics, silt fences, erosion control mats |
| Permanent Control BMPs | Straw bale barriers, filter fabrics, silt fences |
| Runoff Pollution | Deposition of sediment, heavy metals, oils, toxic substances, debris, litter, pesticides, fertilizers, antifreeze, engine oil, rubber and metal deposits, discarded cups, plastic bags, cigarette butts, pet waste |
| Pollution Prevention Techniques | Evaluate alternatives for incorporating a road system or bridge into the natural characteristics of the site, analyze environmental features, develop erosion and sediment control plans |
| Management Measures | Best management practices (BMPs), inspection and maintenance, runoff controls, slope protection, grass strips, temporary sediment traps, silt fences, diversion trenches |
| Regulations | Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991, Coastal Zone Act Reauthorization Amendments (CZARA) of 1990, National Pollutant Discharge Elimination System (NPDES) |
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What You'll Learn
Sedimentation and erosion
Road construction, maintenance, and use can generate a significant amount of pollution, including sedimentation and erosion. Sedimentation refers to the deposition of sediment that can smother aquatic habitats and clog waterways. Erosion, on the other hand, is the process by which soil and rock are worn away and transported by wind or water.
Causes of Sedimentation and Erosion
Several factors contribute to sedimentation and erosion during road construction:
- Poor Planning and Construction Practices: Inadequate planning and construction techniques can increase the risk of sedimentation and erosion. For example, constructing roads perpendicular to slopes instead of parallel can disrupt natural drainage patterns, leading to increased earth disturbance.
- Disturbance of Vegetated Areas: Wetlands and vegetated areas near water bodies provide natural filtration and help maintain water quality. However, construction activities can damage these areas, reducing their water quality benefits and increasing sedimentation and erosion.
- Road Density and Skid Trails: The density of roads and the presence of skid trails and spur roads contribute to surface erosion. These pathways can become routes for sediment to enter watercourses directly.
- Road Location and Slope: Roads constructed on steep slopes or unstable soils can experience failures and landslides, leading to increased sedimentation and erosion.
- Winter Logging: During winter, truck wheels can pump fine sediment from the road bed to the surface, exacerbating the issue of sedimentation in nearby water bodies.
Prevention and Mitigation
To prevent and mitigate the impacts of sedimentation and erosion during road construction, the following measures can be implemented:
- Advance Planning and Pollution Prevention: Proper planning and incorporation of pollution prevention techniques are crucial. This includes evaluating alternatives that work with the natural characteristics of the site, such as topography, drainage patterns, and existing land use.
- Erosion and Sediment Control (ESC) Plans: Develop comprehensive ESC plans prior to construction. These plans should include best management practices (BMPs) suitable for the regional climate and natural features.
- Runoff Control: Implement runoff control measures to prevent sediment-laden runoff from reaching water bodies. This includes using sediment and runoff barriers, stabilizing disturbed areas, and controlling runoff velocities.
- Vegetative Practices: Maximize vegetative cover during construction to prevent soil erosion. Techniques such as seeding, mulching, and using erosion control blankets can help stabilize exposed soil.
- Inspection and Maintenance: Regular inspection and maintenance of BMPs are essential to ensure their effectiveness during and after construction. Educate personnel about ESC plan requirements and enforce compliance with adopted practices.
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Heavy metals
Plants near busy roads, for example, have been shown to accumulate heavy metals from vehicle emissions. The mobility of heavy metals in the soil is influenced by redox conditions and acidity, with many heavy metals being more mobile under acidic conditions. This can have detrimental effects on biological processes in plants, animals, microorganisms, and other organisms.
Runoff pollution from road construction can have significant ecological impacts. It can lead to the deterioration of water quality and contribute to fish kills. Additionally, heavy metals can be toxic to other aquatic organisms and disrupt the natural balance of the ecosystem. Implementing effective erosion and sediment control (ESC) plans and best management practices (BMPs) can help mitigate these issues.
ESC plans involve developing site-specific strategies to minimize the impacts of runoff waters on construction activities. This includes utilizing structural and non-structural measures, such as straw bale barriers, filter fabrics, silt fences, and erosion control mats. BMPs, on the other hand, are practices used to contain and manage polluted runoff. Regular inspection and maintenance of BMPs are crucial to ensure their effectiveness during and after construction.
To further reduce the impact of road construction on waterways, it is essential to consider pollution prevention techniques during the planning stages of road projects. This includes evaluating alternatives that incorporate road systems into the natural characteristics of the site, analyzing environmental features such as topography, drainage patterns, and soils, and implementing runoff-control measures during construction. By taking proactive measures, the amount of pollutants, including heavy metals, entering waterways can be significantly reduced.
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Oils and toxic substances
Oils and other toxic substances are among the most common pollutants of waterways due to road construction. During construction, automotive oils, heavy metals, and other toxic substances can leak and spill, and construction traffic can cause spillage. These pollutants are then absorbed by the soil and carried with runoff water to nearby lakes, rivers, and bays.
To prevent this, runoff-control measures can be installed during road construction to reduce runoff pollution. This can be done by developing and implementing a comprehensive erosion and sediment control (ESC) plan, which includes best management practices (BMPs) such as regular inspection and maintenance of BMPs, and the use of straw bale barriers and filter fabrics to prevent the deterioration and spread of pollutants.
Planning for pollution prevention and control measures is essential to the success of erosion control. This includes evaluating alternatives for incorporating road systems into the natural characteristics of the site, analyzing environmental features such as drainage patterns and soils, and developing site-specific ESC plans prior to construction.
The EPA has developed regulations and programs to address runoff pollution, such as the National Pollutant Discharge Elimination System (NPDES) and the Coastal Zone Act Reauthorization Amendments (CZARA), which aim to protect coastal waters from runoff pollution by requiring construction sites to obtain permits and implement management measures to control the addition of pollutants to waterways.
By implementing these measures and practices, the impact of road construction on nearby waterways can be significantly reduced, protecting aquatic habitats, water quality, and public health.
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Pesticides and fertilizers
Indoor sewer drains collect wastewater from toilets, sinks, washing machines, and showers in homes, restaurants, businesses, and other buildings. This wastewater is treated at facilities before being released into waterways. However, wastewater treatment plants are unable to remove all pesticides, so these chemicals are released into the waterways with the treated water.
Applying pesticides to the soil as granules or drenches or spilling garden chemicals onto the soil can allow them to enter the groundwater below. Some pesticides can percolate with water through the soil and leach downward into underground aquifers, contaminating groundwater used for drinking.
To ensure that pesticides and fertilizers do not end up in waterways, it is important to apply them under the right weather conditions. It is recommended to apply them when the weather is calm, with wind speeds less than 10 mph, and no rain or snow forecast. Pyrethroids, organophosphates, and fipronil are highly toxic to aquatic organisms and are commonly found polluting waterways. Limiting the use of these pesticides or using them in ways that minimize their movement into water is essential.
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Litter and debris
Roads, highways, and bridges are a significant source of pollution to bodies of water. This pollution is generated during road construction, maintenance, and use. Poor planning can contribute to pollution problems. For example, building roads and bridges that impact riparian areas adjacent to surface waters and wetland areas can reduce water quality. This is because these vegetated areas naturally filter pollutants out of water passing through them.
To prevent and control this type of pollution, runoff-control measures can be installed at the time of road, highway, and bridge construction. For example, an erosion and sediment control (ESC) plan that incorporates best management practices (BMPs) can be effective. BMPs are economically achievable measures to control the addition of pollutants to coastal waters. They include permanent erosion and sediment control devices that are both structural and nonstructural. For instance, straw bale barriers can be used to slow down runoff flow and create a pond behind the barrier where sediment can settle. Filter fabrics are another BMP; they are engineering fabrics designed to retain sediment particles of a certain size while allowing water to pass through.
Applying management measures and best management practices during the planning, construction, operation, and maintenance of highway systems can also help to prevent and control runoff pollution. These practices should be incorporated into the project design and include evaluating alternatives for incorporating a road system or bridge into the natural characteristics of the site and analyzing environmental features such as topography, drainage patterns, soils, climate, and existing land use.
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Frequently asked questions
Runoff pollution is when rainwater or melting snow washes off roads, carrying dirt, debris, oils, litter, and other contaminants into nearby streams, rivers, and bays.
Sources of runoff pollution include road construction, maintenance, and use. Construction activities, such as earthmoving and soil disturbance, can increase sedimentation and erosion, leading to muddy waters and ecological problems.
Road construction can pollute waterways by releasing heavy metals, oils, toxic substances, and debris into the soil, which then gets carried by runoff water into nearby water bodies. Poor planning and construction near waterways can also impact water quality.
Waterway pollution from road construction can be prevented through proper planning, education, inspection, and maintenance. Implementing erosion and sediment control (ESC) plans, best management practices (BMPs), and runoff control measures can effectively reduce pollution during and after construction.
