Brownfield Redevelopment

Greenfields, brownfields, greyfields... These all fall under the category of possible land used for building new construction. A lot of development has focused on greenfields, usually grassy, forested areas outside of cities. Unfortunately, this has resulted in leap-frog development and suburban sprawl. A new focus on growth within cities is now targeting previous industrial sites, in other words, brownfields. Brownfield remediation and redevelopment are a series of steps and processes to renew the land for future use. But how does it work? What are the benefits of this? Let's find out!

Brownfield Redevelopment Definition

A brownfield site is an underutilised or abandoned area with the "potential presence of a hazardous substance, pollutant, or contaminant."¹ This is because these sites may have previously hosted industrial factories, gas stations, or landfills. As a result, local soil, water, and even air quality are compromised and in need of cleaning or detoxing. The level of "clean-up" depends on the condition of the site and what it previously hosted. This clean-up is known as brownfield remediation. After remediation, brownfield redevelopment is then possible through the construction of new homes, parks, or businesses.

Several countries have promoted brownfield remediation and redevelopment programs. Canada, the US, and the UK have all funded programs to redevelop brownfield sites. This is because these countries underwent rapid industrialisation during a time of little environmental protection. As economies move into deindustrialisation, local and federal governments must contend with abandoned, unused, and contaminated sites. The US Environmental Protection Agency (EPA) has identified over 450,000 brownfield sites in the US alone.¹

Urban Sustainability

Due to historical land-use policies, locations within urban cores were zoned for industrial activity. With rising issues of housing affordability, suburban sprawl, and the negative environmental effects of car dependency, brownfield redevelopment has been promoted as a sustainable land use strategy. This is because the sites can be used for new housing, offices, or other use-sites, and can create new employment while, at the same time, cleaning up and re-using highly-desirable land.

Fig. 1 - Former twine factory on the 3 Suisses logistics wasteland in Wasquehal, France; An example of a brownfield site

Brownfield redevelopment is part of smart growth strategies to prevent suburban sprawl and leap-frog development.² Leap-frog development occurs because developers are incentivised to purchase cheaper land outside of cities, leaving large distances between areas that influence mobility and promote car use.

Brownfield Redevelopment Process

The brownfield redevelopment process varies by country, state, and project objective. Some sites are significantly more contaminated than others and require different levels of intervention. The EPA provides a comprehensive guide to brownfield redevelopment.

Risk-Based Clean Up

The remediation process depends on the future intended use of the land. The EPA refers to it as a risk-based clean-up. Risk-based clean-up takes into account specific populations (children, pregnant women, elderly, immuno-compromised) and the length of time they may spend on the land. For instance, brownfields planned for residential or green space redevelopment will require more time and resources to clean-up. Meanwhile, planned commercial and industrial development requires less time and resources.

Environmental site assessments are necessary to understand previous and current site conditions and potential contaminants. Environmental site assessments include site visits, historical site research, interviews with property owners and locals in the area, and multiple local agency involvements. The process can take months to years of time and investment, which can deter some developers and stakeholders.

Remediation Methods

If an area is considered contaminated, a series of remediation methods may be necessary. Remediation methods vary by site and depend on present contamination.

If soil is contaminated, excavation, capping, in-situ treatment or bioremediation may be performed. Excavation includes the removal of contaminants, and replacement with clean soil may be a solution. If contamination is deeper in the soil, capping can follow excavation by fitting a layer of geotextile or clean soil and preventing contamination from spreading.

In more extreme cases of contamination, in-situ treatment or on-site treatment may be required. In-situ treatment can include the injection of chemicals into contaminated soil to break down toxic compounds. Bioremediation is the injection of microbes, nutrients, or oxygen to increase microbial growth, which can further break down contaminants. Phytoremediation is the use of plant roots for microbial growth.

In some cases, the presence of lead and asbestos can be very challenging during remediation. The use of asbestos in construction materials was widespread until 1986.³ Exposure to asbestos has been linked to mesothelioma and lung cancer. Meanwhile, lead was a common ingredient in paint until 1979. Exposure to lead is especially concerning for children as it is linked to learning disorders and issues with memory. The removal and treatment of these chemicals require the coordination of several agencies and organisations and can take many years.

Fig. 2 - Superfund Sites in the US (2013); Red dots indicate high clean-up priority, yellow is proposed, and green means cleaned

Benefits of Brownfield Redevelopment

There are numerous benefits of brownfield remediation and redevelopment. Remediation through different clean-up methods reduces health risks linked to exposure to toxic contaminants. Although these projects should occur indiscriminately across the US, higher-income and visible areas are more likely to see brownfield redevelopment.

Brownfields tend to be connected to other existing infrastructure and may be strategically located in downtown areas. Redeveloping these areas for new use saves on costs, prevents the need to build on green spaces, and reduces the expansion of concrete surfaces.⁴ Additionally, because public transportation services may be readily available, there's a greater possibility for transit-oriented development, another major smart growth policy.

Redeveloped brownfield sites have the potential to become new homes, offices, and businesses. The location of these sites within downtown cores makes it an attractive option for job and housing growth by providing new purposes and increasing property values.⁴ Using mixed-use development methods in new construction also promotes walkability and decreases the need for private vehicle use.

Brownfield Redevelopment Examples

There are many cities in the US with designated industrial sites within their urban cores. As cities deindustrialised, these sites remain unused and abandoned. However, brownfield remediation and redevelopment options have brought new life to these areas and promoted smart growth policies.

Denver, Colorado

Denver, Colorado, is a rapidly growing mid-sized city in the US. Historically, Denver’s strategic location served as a major rail link to deliver goods across the US. It was the host of many manufacturing and industrial facilities, primarily around its downtown areas of Union Station and River North district (RiNo).

Fig. 3 - Street Art in River North, Denver, Colorado; RiNo hosts many brownfield redevelopment projects

The City of Denver has a brownfields program that assists local developers with site assistance and fund sourcing to clean-up and redevelop sites in Denver. Redeveloped sites usually include mixed-use development and even affordable housing options.⁵ For instance, the Denver Housing Authority redeveloped the Mariposa District, adding hundreds of new housing units while reserving some for low-income and elderly residents. The Mariposa District is one of many transit-oriented development projects in the city, with access to light rail and walkable designs.

Another example is the Central Platte Campus project which was used to house the General Chemical manufacturing facilities. Since the late 1800s, these manufacturing facilities have polluted much of the local area, requiring extensive soil cleaning. Excavation, capping, and in-situ treatments were all used with ongoing groundwater monitoring. As a result of massive coordination between different Denver agencies, including Denver's Department of Transportation & Infrastructure and the City's Wastewater authority, new City buildings and functions operate from the Central Platte Campus. The project has won several awards for its environmental clean-up and land redevelopment.