Retention & Detention

Dating back as early as 500 B.C. and modernized in Germany in the 1960s, Green Roofs have been around for longer than we think. They allow us to control and detain water for multiple purposes. Sustainablu systems have advanced with state-of-the-art stormwater detention and retention capabilities that go beyond all current Sustainable Urban Drainage System (SuDS - U.K.) requirements. This includes concepts that rely on sponging components or multiple layers of fabrics


 Stormwater &        
 The Water Cycle

The Water Cycle is nothing new. Working with rather than against, Sustainablu systems are developed to support the natural water cycle.

With the help from data collectors, soil biologists, and vegetation specialists, Sustainablu has been able to provide customized projects for over 40 years.

Every roof and its climate is different, and Sustainablu is easily able to make adjustments to components and system specifications for any given system. 

Stormwater Retention & Detention


Stormwater Retention

This is where water is retained without releasing it.

For example, you have a bucket without a hole in the bottom. When water is poured in and once the bucket is full, it will overflow in the same ratio as it is poured in.


Stormwater Detention

This is where stormwater is retained for a limited and/or defined time.

For example, you have a bucket with a hole on the bottom. This hole releases the water slower than the amount of water that was poured in. If the bucket is full (because the release is slower) it will overflow in the same amount as it is poured in.

Learn About Stormwater

Grey Infrastructure can also be identified as man-made structures. With their lack of consideration for the water cycle, stormwater is hardly slowed down. This causes the overloading of drainage capacity and sewer systems. As a results, flooding often occurs.

BlueGreen Infrastructure reintroduces natural landscapes and vegetation back into the built environment. They help to reduce runoff water when combined with Grey Infrastructure. In addition, it filters pollutants, protects water quality, and mitigates the risk of flooding.

Sustainablu addresses Grey Infrastructure issues and provides affordable smart controls at the source where precipitation hits an impervious surface. A carefully engineered combination of nature-based infrastructure with smart run-off controls allows an integrated approach to Blu-Green Stormwater Management to design resilient urban landscapes.

Grey Infrastructure Insight

Being aware of the consequences of Grey Infrustructure 


High Cost for Conventional Infrastructure

Grey Infrastructure is expensive. In 2010, New York City estimated that updating the city's stormwater system to control combined sewer overflows using Grey Infrustructure would cost approximately $6.8 billion over 20 years. By blending Grey and Blu-Green Systems, the city reduced its estimated cost by $1.5 billion.


Economic Losses from Flooding

In 2016, 4 flooding events and 8 severe storms have caused damages exceeding $1 billion across the United States.


"Once In A Century" Storm Surges

Climate change is causing increasing temperatures and rising sea levels. This is creating increasingly frequent and dramatic storm surges that threaten low-lying parts of cities. In many coastal cities, “once in a century” storm surges may occur once a decade in the future.


Public Health Risks

860 communities across the U.S. with a total population of 40 million people have combined sewer systems. During heavy rainfall events that overburden the Grey Infrastructure System, untreated stormwater and sewage flows directly into local bodies of water. This causes serious health risks and environmental pollution.


Urban Flooding

Storms of all magnitudes can cause flooding to homes and businesses, disrupt lives, and damage property. A study of Cook County, IL found that urban flooding is chronic and systemic. Property owners suffered an average of $6,000 in damages per flooding event, and 87% of homeowners surveyed had experienced multiple flooding events. In addition to damaging buildings, flooding can disrupt street operations and prevent safe transportation.


531 S. Water Street                     
Milwaukee, WI 53204