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What is Stormwater Management and Why is it Important?

Stormwater management is a crucial practice designed to handle excess runoff from rain and melting snow that flows over streets, parking lots, roofs, and other impermeable surfaces. Without proper management, this runoff can overwhelm storm drains, pollute waters, and cause erosion and flooding. Effective stormwater design protects our environment by reducing the spread of pollutants…

Frank Cuffaro

February 15, 2024

10 mins read

Mashomuck image civil engineering

Stormwater management is a crucial practice designed to handle excess runoff from rain and melting snow that flows over streets, parking lots, roofs, and other impermeable surfaces. Without proper management, this runoff can overwhelm storm drains, pollute waters, and cause erosion and flooding.

Effective stormwater design protects our environment by reducing the spread of pollutants into rivers and oceans. It also safeguards communities from flood risks by managing heavy rainfall in urban areas where natural absorption is limited due to concrete and asphalt surfaces.

Significance of Stormwater Management to Residential & Commercial Construction

Efficient stormwater management reduces or eliminates erosion and sediment loading to water bodies during construction while controlling the impact of runoff on water quality. And it’s not just good practice—it’s a legal requirement. Projects must comply with various local codes and regulations that dictate how they handle rainwater harvesting and surface runoffs on-site.

Why Do We Need Stormwater Systems?

Unchecked stormwater can wreak havoc on our environment, and communities rely on effective management for public health and safety. Understanding the significance of proper stormwater management is key to seeing the risk of improper practice. Let’s examine what’s at stake.

Environmental Impact

Stormwater management plays a crucial role in safeguarding water quality and protecting natural ecosystems. Excessive stormwater runoff can lead to polluted water that causes erosion, flooding, and even a loss of biodiversity. Introducing effective strategies is vital in mitigating these adverse environmental impacts and ensuring polluted stormwater is treated effectively before it reaches natural water bodies.

Cities and towns must also prioritize managing runoff to prevent long-term harmful effects, such as eutrophication in local lakes, rivers, and bays caused by excess nutrients from urban areas.

Rising concerns about the impact of stormwater systems on urban infrastructure stems from increasing precipitation intensity and prevalence of impervious surfaces due to development. This reality requires sustainable solutions that balance development needs with ecological preservation.

Community Well-Being

Stormwater management solutions like green roofs, rain gardens, and rain harvesting systems add value to properties by blending functionality and sustainability. They also prevent floods and infrastructure damage in residential areas, creating a safer and healthier living environment for community residents. 

National and Local Legal Requirements 

Government bodies like the Environmental Protection Agency mandate regulations at both national and local levels to manage and control the release of hazardous materials into the environment through stormwater. Developers must consider the effects of stormwater before, during, and after a project to comply.

State Pollutant Discharge Elimination System (SPDES)

One example of this type of regulation is a State Pollutant Discharge Elimination System (SPDES). This New York state-level program is designed to limit pollutants discharged from a site via process water, processed wastewater, or stormwater. Construction projects that require this permit must actively mitigate the level of pollutants that could potentially affect surrounding areas in the event of stormwater runoff.

Stormwater Pollution Prevention Plan (SWPPP) 

A Stormwater Pollution Prevention Plan (SWPPP) is the resource used by SPDES-permitted construction projects to reduce runoff and sedimentation by containing stormwater on-site. By doing so, an SWPPP helps control the impact of runoff on surrounding bodies of water and prevent pollution.  

Stormwater Management During Residential and Commercial Construction

Managing stormwater during construction is a critical measure. Proactive regulatory research and environmental consideration ensure compliance and alleviate the impact of construction on surrounding bodies of water.

Regulatory Considerations

Residential and commercial properties are often required to follow local and national stormwater regulations. Legislation seeks to promote responsible practices, protecting water quality and ecosystems in surrounding areas both during construction and long after.

Erosion and Sediment Control Measures

As stormwater flows through a construction site, it picks up pollutants such as sediment, debris, chemicals, and nutrients. Increased flow rates result in increased erosion and sedimentation downstream, which can damage or destroy aquatic habitats. Minimizing this impact requires erosion and sediment control measures, many of which we outline below.

Silt Fences

One of the most widely used erosion control measures, silt fences are made of permeable fabric stretched between metal or wooden poles. This creates a barrier that water can pass through while trapping sediment, preventing any contamination.

Silt fences are often used in pre-construction and demolition for coastal sites to protect waterways and aquatic ecosystems from pollutants that may travel in runoff. 

Sediment Basins

Catch basin diagram

Sediment basins capture and remove sediment from stormwater runoff. They temporarily store stormwater, allowing the sediments to settle out before discharge. Around 80% effective in removing sediment from stormwater, these basins are crucial in helping keep pollutants out of water bodies.

Soil Stockpile Areas

Soil stockpile diagram

A soil stockpile is formed from topsoil excavated throughout the course of construction. When these areas are improperly managed, sediment and pollutants may wash off into nearby bodies of water via runoff. Handling stockpiles appropriately is essential to minimizing environmental impact during and after land development.

Hay Bales

Hay bale diagram

Hay bales are majorly effective in capturing sediment and slowing down stormwater runoff, helping to prevent both soil erosion and water pollution.

Whether used in urban, rural, or even agricultural areas, this simple yet effective measure can protect water quality by effectively mitigating stormwater.

Temporary Seeding & Mulching

By establishing quick ground cover, temporary seeding and mulching helps to stabilize disturbed soil areas, prevent erosion, and promote the infiltration of rainfall—protecting water quality and minimizing environmental impact.

Temporary seeding involves quickly establishing vegetation with fast-growing grasses or plants that provide immediate soil stabilization. Mulching complements this process by covering seeded areas with organic material like straw or wood chips to protect against erosion caused by wind and water.

In addition to preventing erosion, both practices facilitate the absorption of stormwater into the soil, contributing to sustainable water resources while maintaining site integrity during construction.

Construction Entrance Considerations

Implementing appropriate measures like stabilized construction entrances, gravel pads, or wheel wash systems prevents potential soil erosion and tracking of sediments onto public roads.

Post-Construction Residential and Commercial Stormwater Management

underground stormwater retention system diagram

Permanent Measures for Collecting Runoff from Impervious Surfaces

Sustainable stormwater management systems are crucial in maintaining community well-being and supporting sustainable urban development. Runoff from impervious surfaces such as paved roads, parking lots, sidewalks, rooftops, driveways, patios and more requires permanent solutions post-construction.

Systems like underground detention/retention systems, infiltration basins, green roofs, permeable surfaces, and rain gardens are commonly employed. Similarly, green roofs and permeable surfaces in residential areas reduce runoff by letting water infiltrate through soil rather than flowing over impervious areas.

Implementing these techniques reduces strain on traditional infrastructure while replenishing groundwater sources. Sufficient groundwater recharge enhances environmental sustainability by minimizing surface runoff pollution into natural waterways.  

Underground Detention/Retention 

Underground detention/retention is the capture and storage of stormwater runoff in large underground pipes or vaults. This approach to stormwater management may be especially relevant to construction projects dealing with size constraints—underground retention saves space, prevents flooding of local water sources, and helps development meet environmental regulations.

Underground retention is often practiced in residential and commercial construction through the use of drywells (underground structures lined with perforated casings that collect surface water), CULTEC chambers (dome-shaped, full open bottom corrugated chambers that allow water storage until runoff can be absorbed by soil), and gravel beds. 

Infiltration Basins

An infiltration basin is a shallow water confinement with a grass or sand base meant to hold excess runoff until it soaks into the ground. Some may drain quickly, while others act as permanent ponds that increase or decrease water level depending on stormwater collection.

This practice can be integral to stormwater management by decreasing peak runoff flow rates and volume, increasing natural groundwater recharge, and mitigating excess runoff.

Green Roofs

A green roof is a system that incorporates vegetation, soil, and other various layers to facilitate plant growth on a structure’s roof. This solution reduces the volume and velocity of runoff by slowing down, absorbing, and retaining rainwater. In turn, these positive effects alleviate strain on local stormwater management systems, reduce the risk of flooding, and support the natural hydrological water cycle.

Green roofs also play a role in enhancing water quality by preventing pollution and contributing to the conservation of stored water, a resource often used for irrigation in urban and rural areas. 

Substituting Permeable Surfaces

Substituting permeable surfaces where possible is a great long-term choice for urban stormwater management. This methodology helps mitigate flooding, recharge groundwater supplies, and reduce water pollution.

In urban construction, permeable surface adoption can be as simple as property owners choosing to substitute an asphalt driveway with a gravel driveway. Gravel will allow rainwater or melting snow to permeate the underlying soil, significantly reducing excess runoff and local water contamination.

Rain Gardens

A rain garden is a depressed area in the landscape that collects rain water from a roof, driveway, or street. After runoff is captured, it’s absorbed back into the ground, preventing contaminants from entering drains and waterways.
This method serves as natural drainage systems and is often planted with native vegetation that can tolerate wet and dry conditions, effectively removing pollutants such as sediment, nutrients, and heavy metals from stormwater.

Their integration into urban landscapes provides green spaces and improves aesthetic/visual property appeal with the advantage of versatility: they can be retrofitted into existing buildings and developments.

Stormwater Management + DiLandro Andrews Engineering

Mashomuck image civil engineering

The DiLandro Andrews Engineering team is well-versed in strategizing stormwater management before, during, and after any project that mandates the practice. Our expertise lends clients the confidence that any residential or commercial civil engineering project will adhere to relevant stormwater management practices and local municipal code compliance.

National and Local Regulation Expertise

National and local regulations often mandate how stormwater management is handled in residential and commercial construction projects. These types of legal requirements can be complicated and difficult to understand—does a SPDES always need a SWPPP? What’s the difference between the two?

Our firm is well-versed in guiding clientele through the process to ensure projects are not only managing stormwater efficiently and effectively, but are remaining compliant with local regulations while doing so.

Future Innovations in Stormwater Management

As urban areas continue to grow and climate concerns increase, increasingly innovative solutions will be necessary to face challenges posed by increased runoff and pollution. Thankfully, stormwater management advances rapidly as green infrastructure is further developed.

With innovative stormwater management on our side, we can build resilient and sustainable systems for the future of our communities and the environment.