Introduction

For decades, cities have relied on gray infrastructure — stormwater pipes, culverts, and treatment plants — to manage urban stormwater. While these systems serve an essential function, they are increasingly overburdened, expensive to maintain, and ill-equipped to handle modern climate challenges. Heavy rainfall overwhelms drainage systems, pollutants flow freely into watersheds, and aging pipes require costly repairs.

But there is a more sustainable approach: green infrastructure (GI), which works with natural systems to absorb, slow, and treat stormwater. When integrated effectively, GI relieves pressure on gray infrastructure, reducing maintenance costs and extending system lifespan; however, cities often face challenges in implementing green solutions, often due to space constraints. This is where innovative GI solutions like Marino Cell emerge to help solve these real-estate conundrums — the modular system seamlessly integrates green and gray infrastructure to create a more effective, resilient stormwater strategy.

Challenges of Gray Infrastructure

Traditional stormwater management relies on underground pipes that rapidly collect and convey runoff to treatment plants and nearby water bodies. The problem is that this approach presents several costly and unsustainable challenges.

• High Maintenance Costs: Pipes accumulate sediment, debris, and pollutants, requiring frequent cleaning and costly upkeep. Aging infrastructure requires expensive repairs or full replacement, which can cost cities millions.

• Increased Flooding and Overflows: During heavy storms, storm sewers struggle to handle excess runoff, leading to urban flooding. In cities with combined sewer systems (CSOs), stormwater mixes with sewage and, during major rain events, drains right into local watersheds.

• Water Quality Issues: Gray infrastructure transports, but does not treat, stormwater, allowing pollutants like oil, heavy metals, and fertilizers to reach waterways.

One strategy for preventing these gray infrastructure challenges is to give them some on-site assistance in the form of green infrastructure.

How GI Relieves Stormwater Stress

Green infrastructure helps address these challenges by slowing, absorbing, and filtering stormwater naturally, right at its source. Instead of funneling all runoff into underground pipes, GI allows cities to manage stormwater where it falls.

• Reduced Stormwater Volume: GI captures and absorbs rain where it falls, reducing the amount of runoff entering storm drains.
• Reduced Stormwater Flow Rate: Vegetation and engineered systems slow down water, preventing flash floods and sewer surges.
• Pollutant Removal: Plants, soil, and biofiltration media remove contaminants naturally, reducing treatment needs. By keeping debris and sediment out of pipes, GI reduces clogging and prolongs infrastructure lifespan.

Additionally, green infrastructure enhances climate resilience by mitigating heat island effects, improving air quality, and capturing excess rainfall for drier periods. Expanding tree canopies and increasing permeable landscapes help cities adapt to more extreme weather patterns while simultaneously providing aesthetic and recreational benefits.

GI is obviously a useful strategy in urban stormwater development — but traditional bioretention systems, like “daylighted” raingardens, are space prohibitive. Utilizing innovative solutions that fit within the design plans of tight built-environment projects is key.

Bridging Green and Gray with Marino Cell

While green infrastructure is highly effective, space constraints present challenges in most urban development. This is where DeepRoot’s Marino Cell plays a crucial role, acting as a versatile bridge between green and gray infrastructure to maximize stormwater management efficiency.

Marino Cell is a modular, below-ground stormwater management system designed to provide stormwater storage and infiltration. Unlike traditional underground retention systems, Marino Cell is engineered to integrate seamlessly in nearly any environment, without requiring any surface space.

So, in what ways does Marino Cell’s LID versatility help enhance the stormwater efficiency of urban areas and in turn relieve stress on the gray infrastructure system?

One of the most significant benefits of Marino Cell is its ability to reduce the burden on storm sewers. By retaining and gradually releasing stormwater, it prevents sudden influxes into underground pipes, reducing the risk of overloading the system. This controlled release decreases maintenance costs and minimizes the need for expensive pipe expansions. Additionally, the system fosters healthier urban tree canopies by providing on-site irrigation, which further enhances stormwater absorption while cooling cities and improving air quality.

Marino Cell is particularly valuable in space-constrained urban environments where traditional green infrastructure solutions are difficult to implement. Its underground design allows cities to integrate stormwater retention beneath sidewalks, plazas, and roads without compromising surface usability. This makes it an ideal solution for municipalities looking to incorporate more green infrastructure without sacrificing land availability.

Not only does Marino Cell help alleviate pressure on gray infrastructure, but it can actually work in tandem with raingardens for maximum efficiency. By installing beneath a “daylighted” raingarden, replacing traditional aggregate, Marino Cell increases the capacity of that raingarden — indeed, an independent study conducted by Geosyntec confirmed that a raingarden with a two-deep Marino Cell installed below can reduce its footprint by as much as 30% while managing the same amount of stormwater!

Conclusion: The Future of Stormwater Management is Hybrid

Gray infrastructure remains a necessary component of urban stormwater management, but relying on pipes alone is costly and unsustainable. Green infrastructure provides a natural, cost-effective way to reduce flooding, improve water quality, and extend the lifespan of existing drainage systems. And some of the most clever GI strategies, like Marino Cell, can be integrated in nearly any environment, supporting gray infrastructure by treating stormwater where it falls.