What are the best BMPs for reducing runoff and improving water quality in urban areas?

Urban areas face many challenges when it comes to managing stormwater runoff and protecting water quality. Impervious surfaces, such as roads, roofs, and parking lots, increase the volume and velocity of runoff, carrying pollutants and sediments into streams, lakes, and rivers. This can cause flooding, erosion, habitat loss, and health risks for humans and wildlife. To address these issues, land developers can implement best management practices (BMPs) that reduce runoff and improve water quality. BMPs are design features, techniques, or measures that prevent or minimize the impacts of stormwater runoff on the environment. In this article, we will discuss some of the best BMPs for urban areas and how they can benefit your project and the community.

1 Infiltration BMPs

One of the best ways to reduce runoff and improve water quality is to infiltrate stormwater into the ground, where it can replenish groundwater, filter pollutants, and moderate stream flows. Infiltration BMPs are designed to capture and store runoff and allow it to seep into the soil. Some examples of infiltration BMPs are rain gardens, bioretention basins, permeable pavements, dry wells, and infiltration trenches. These BMPs can enhance the aesthetics and functionality of your site, as well as provide habitat for plants and animals. However, they require careful site selection, design, and maintenance to avoid clogging, ponding, or contamination.

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Michelle Mausolf

Project Manager, RPBio, CPESC
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An important aspect to consider in addition to infiltration BMPs is the local area of impermeable surfaces, like asphalt and concrete, that prevent on-site infiltration and create run-off. By reducing impermeable surfaces where practical, and including green spaces, throughout a development project developers can better advantage of natural infiltration.

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David Roger Dyess

Property Management to Planned,Permitted and construction execution
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In ground storage is ok after filtration. Putting storm water runoff into the ground works but not everywhere. IE, some areas geology may not be suitable for this practice like South Florida etc. Retntion,Detention is better in my mind and experience. Treat it before putting it in the ground.

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2 Detention BMPs

Another way to reduce runoff and improve water quality is to detain stormwater temporarily and release it slowly to the downstream system. Detention BMPs are designed to collect and hold runoff for a short period of time, usually less than 24 hours, and then discharge it at a controlled rate. Some examples of detention BMPs are detention ponds, wet ponds, underground vaults, and hydrodynamic separators. These BMPs can reduce peak flows, prevent flooding, and remove some pollutants and sediments from runoff. However, they may not provide enough water quality treatment, especially for nutrients and bacteria, and may require frequent maintenance to remove accumulated solids and debris.

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Michelle Mausolf

Project Manager, RPBio, CPESC
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Detention BMPs in land development are also required during the construction phase for best management of soil erosion. Structures like check-dams, water bars, and biodegradable wattles direct and slow runoff to reduce erosion scour and sedimentation into local wetlands and watercourses. In my experience in the oil and gas and mining sectors, detention BMPs are effective at reducing sedimentation when combined with other erosion control mitigations and are regularly maintained.

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David Roger Dyess

Property Management to Planned,Permitted and construction execution
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Sound like the Florida Everglades. Retention,Detention in a large integrated system is effective treatment. Putting 10 pounds in a 2 ounce bag is not. Systems should be monitored in terms of pollutants in the system and action taken after sampling. My experience is with large scale development where this practice is land intensive but provides opportunities to sell waterfront views if water groundwater table allows. In some regions water is so scarce that runoff is captured and pumped underground hoping for pollutant removal. In my mind just puts pollution deeper.

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3 Filtration BMPs

A third way to reduce runoff and improve water quality is to filter stormwater through a medium that removes pollutants and sediments. Filtration BMPs are designed to pass runoff through a layer of sand, gravel, soil, or vegetation that traps and absorbs contaminants. Some examples of filtration BMPs are sand filters, vegetated swales, grassed filter strips, and green roofs. These BMPs can provide effective water quality treatment, especially for suspended solids, metals, and hydrocarbons, and can also reduce runoff volume and temperature. However, they may not be suitable for high-flow or high-load situations, and may require regular maintenance to replace or restore the filter media.

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Michelle Mausolf

Project Manager, RPBio, CPESC
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The BMPs listed in this article; sand, gravel, soil or vegetation, may be effective in a limited sense to slow runoff and allow pollutants like sediment or larger organic materials to settle out. Their effectiveness is usually limited to a low-flow, low velocity runoff situation. The information contained in this paragraph does not clarify how the listed BMPs would be effective to filter out metals or hydrocarbons, and caution should be used when choosing appropriate mitigations for these pollutants. As specialized system that contains metal and/or hydrocarbon contaminated runoff is necessary to prevent spills into wetlands or watercourses, well beyond a gravel or grass filter strip.

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4 Vegetation BMPs

A fourth way to reduce runoff and improve water quality is to use vegetation to intercept, retain, and transpire stormwater. Vegetation BMPs are designed to incorporate plants, trees, shrubs, or grasses into the landscape that can reduce runoff generation, increase infiltration, provide filtration, and stabilize soils. Some examples of vegetation BMPs are riparian buffers, tree box filters, vegetated roofs, and urban forestry. These BMPs can provide multiple benefits, such as improving air quality, enhancing biodiversity, reducing heat island effect, and creating recreational and educational opportunities. However, they may require careful selection of species, planting, irrigation, and pruning to ensure their survival and performance.

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5 Education BMPs

A fifth way to reduce runoff and improve water quality is to educate and engage the public and stakeholders about the sources and impacts of stormwater pollution and the benefits of BMPs. Education BMPs are designed to increase awareness, knowledge, and behavior change among the target audience through various methods, such as signage, brochures, workshops, demonstrations, or incentives. Some examples of education BMPs are storm drain stenciling, rain barrel programs, adopt-a-stream initiatives, and low-impact development guidelines. These BMPs can foster a sense of stewardship, responsibility, and participation among the community and can complement and enhance the effectiveness of other BMPs. However, they may require ongoing communication, evaluation, and feedback to ensure their relevance and impact.

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6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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David Roger Dyess

Property Management to Planned,Permitted and construction execution
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With development overcrowding the existing environment should be a helpful guide to responsible developers planning the environmental enhancement of what exist instead of building over it. Greed is an issue. Sites that are stripped of its environment are subject to a polluted site in terms of groundwater. Biology can be a guide. Actually is a must as well as an expert water quality design from the beginning.

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Michelle Mausolf

Project Manager, RPBio, CPESC
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A final consideration for runoff is management of runoff into your development site. Clean runoff needs to be directed away from exposed soils and active work areas to minimize the creation of sediment laden water. Intercept BMPs like silt fence, vegetated swales, and water bars are important components of a development project's erosion and sediment control plan.

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What are the best BMPs for reducing runoff and improving water quality in urban areas?

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1 Infiltration BMPs

2 Detention BMPs

3 Filtration BMPs

4 Vegetation BMPs

5 Education BMPs

6 Here’s what else to consider

Land Development

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