top of page
  • Rob Furness

Petroleum Brownfield Site Remediation

Updated: Apr 4

The Petrol/Gas Station Big Picture

Currently, in the USA, there are approximately 450,000 brownfield sites, of which half are estimated to be caused by petroleum contamination due to storage tanks leaking underground (USTs) [1]. These sites cause health problems for the local community and contaminate groundwater and drinking water. As of February 2020, there are approximately 115,000 gas stations in operation in the USA [2].

This is a similar story reflected in Canadian towns and cities where there are an estimated 30,000 contaminated brownfield sites that were formerly gas stations. Cleaning up these sites is a costly affair, and the use of on-site remediation using naturally occurring bacteria and fungi to break down hydrocarbons could lead to savings of 30% of the total clean-up cost [3]. In Kalibrate’s 2020 census, there were 11,908 retail gas stations in Canada, or 3.1 per 10,000 Canadians [4].

It is estimated that within 30 years petrol stations will be a thing of the past, maybe not 30 years but certainly 50 years for most of the world, and this will leave the entire planet with a lot of brownfield contaminated sites to deal with. In the UK, the government are planning to ban the sale or registration of new diesel and petrol cars from 2040 as part of ‘The UK Plan for Tackling Roadside Nitrogen Dioxide Concentrations´, in a report delivered by The Department for Environment, Food and Rural Affairs (DEFRA) with the Department for Transport, any cars that are sold must be zero emissions, and the ban excludes hybrid vehicles [5].

In the UK alone there are currently 8,380 petrol stations [6] that could be facing the end of their time. This will leave several sites that are still creating a hazard and will need to be remediated. In the 1950s there were around 40,000 sites across the UK. These have been in decline as in 2000 the number of gas stations was 13,107 sites. This is mainly due to oil company consolidation. Between 2000 and 2010 there were another 5000 cases of gas stations closing their doors, due to the aggressive pricing strategy of cheap, unbranded fuel by hypermarkets [7].

If we move to a wider view of Europe then as of the end of 2019 Italy led Europe in the number of petrol stations in the country with 21,700, followed by Germany with 14,449 and Turkey in third place with 13,178. The total amount of service stations throughout Europe totalled 138,309, although for some of these figures only the numbers from 2016 and 2017 were available [8]. We can easily see that with the current trend and new European laws many of these sites will become decommissioned and in need of brownfield site remediation.

Without a doubt the world is changing to electric vehicles, GM estimates that by 2023 it will have 20 models of electric vehicles in dealerships around the world. Ford goes further to say they will have 40 models of electric and hybrid vehicles in the world by the middle of the decade. Since the USA is the second-largest car market in the world after China [9] we will see a larger amount of brownfield sites in the USA than most other countries in the world. Current forecasts in the USA suggest that if large car manufacturers have their way, then a decade from now the number of gas stations could be cut by half [10].

Brownfield Sites? What are they?

We have established some numbers now, the scale of the problem that exists now and how it is possibly going to look in ten years, so, what do we do about it? Many companies already work in this specialist field remediating petroleum brownfield sites, with many newer environmentally friendly technologies and new companies entering it, firstly though…

What is a brownfield site? “Brownfield is a term applied to a property where its expansion, redevelopment, or reuse may be complicated by the presence or potential presence of a hazardous substance. A petroleum brownfield is a type of brownfield where the contaminant is petroleum.

Of the estimated 450,000 brownfield sites in the U.S., approximately one-half are thought to be impacted by petroleum, much of it from leaking USTs at old gas stations. These sites blight the surrounding neighbourhoods and threaten human health and the environment. Petroleum can contaminate groundwater, the source of drinking water for nearly half of the U.S. population.” [11]

Let us focus on the USA for the moment and look towards where potentially the largest single market will be for this, although with all the different states having their own budgets it can sometimes be like working with 50 different countries thankfully the US Environment Protection Agency (EPA) being an independent body can apply their guidelines to all states, theoretically.

The EPA has two offices that work jointly on the problems commonly faced in these areas, the Office of Underground Storage Tanks (OUST) and the Office of Brownfields and Land Revitalization (OLBR) work together to focus on the remediation and re-use of petroleum contaminated sites, OUST mainly focuses on the clean-up of leaking underground storage sites prioritising high-risk leaks and sites on federally regulated tanks. OLBR meanwhile awards brownfield grants that go towards assessing and cleaning up petroleum brownfield sites, keeping its focus towards low-risk areas.

“Since its inception in 1995, EPA's Brownfields Program has grown into a results-oriented program that has changed the way contaminated property is perceived, addressed, and managed. Initially, EPA provided small amounts of seed money to local governments that launched hundreds of two-year brownfield pilot projects.”

“Petroleum-contaminated sites were not eligible for traditional brownfields funding. Through the passage of the Small Business Liability Relief and Brownfields Revitalization Act in 2002, brownfields policies that the EPA developed over the years were passed into law. The 2018 Brownfields Utilization, Investment, and Local Development (BUILD) Act reauthorized EPA's liability provisions and state and tribal response programs.” [11]

Health around Brownfield sites.

It has been established from Geographical research that significantly more people are increasingly likely to suffer from poor health living near brownfield sites than those living in areas with little or no brownfield land around them. These findings come from the University of Durham in the UK and suggest that brownfield site remediation should be a policy priority for Local Authority public health teams.

This research carried out in 2014 was the first of its kind to examine the link between poor health in the local population and brownfield site location and recognised the previously overlooked link between brownfields and the environmental influence on health. The Homes and Communities Agency had an estimate then of around 62,000 hectares of brownfield land in England.

The excerpt of the paper goes on to say:

The research is published in the academic journal Environment and Planning A.

Professor Clare Bambra, lead author of the study from Durham’s Department of Geography, said: “Our study shows that local authorities and central government need to prioritise the remediation and regeneration of brownfield land to protect the health of communities.”

Co-author of the study Dr Karen Johnson, from Durham University’s School of Engineering and Computing Sciences and Institute of Hazard, Risk and Resilience said: “Brownfield has potential negative impacts on people’s sense of wellbeing, and this could be psychological or toxicological, or both.

The study used data on brownfield land from the 2009 National Land Use Database, which encompasses around 72 per cent of previously developed land across England. Health data for the study was taken from the 2001 English Census, and data on premature death was used from the Office for National Statistics from 1998-2003. [12]

The benefits of greenfield sites in urban developments

There are many ways to remediate petroleum brownfield sites but undoubtedly the best result would be to create greenfield sites, where the land is not only remediated but then converted into green open spaces, like parks and playgrounds. Perhaps one of the best examples of the benefit of a greenfield site is Central Park in Manhattan, New York. If one were to think of an urban greenfield site this is most likely the place many people think of.

There are many reasons for this, the park itself measures 341 hectares and the real estate around it is some of the most expensive in the world. In the original commissars’ plan of 1811, the park was not included, however, as the city started to grow from 1821 to 1855 and the metropolitan area of New York quadrupled its population the need was recognised for an open space where people go to unwind. Andrew Jackson Downing recognised this and as the first landscape artist in the USA wanted to emulate Hyde Park in London and the Bois de Boulogne in Paris. So in 1853, the New York legislature gave up the area between 59th and 110th streets, and one of the first ‘modern day’ inner-city parks was born [13].

Not every remediated site will reach this lofty status, however, it has been shown that remediating areas into greenfield sites is beneficial to inner-city areas. The New York / New Jersey (NY/NJ) Baykeeper position paper of April 2006 entitled “Brownfields to Greenfields” said it best:

Because most brownfields are found in densely populated urban areas, these properties have significant potential for redevelopment and Greenfields purposes. The benefits of Greenfields are many, particularly in densely populated areas. Greenfields can play a critical role in the human and environmental health of cities. Urban areas traditionally have a dire lack of open space, while shouldering a disproportionate share of industrial pollution. One of the poorest cities in the nation, Newark, New Jersey, suffers from an acute lack of recreational open space; just 5.3% of its land base is open space, which equates to 2.9 acres per 1,000 residents. Balanced Land Use Guidelines suggest that 10 acres per 1,000 people is the minimal amount of developable land that should be set aside as public open space.

The position paper goes on to list the commonly recognized benefits of Greenfields:

  1. Neighbourhood revitalization

  2. Community Health

  3. Environmental justice

  4. Environmental/ecosystem health

Economic benefits and cost savings are listed as quantifiable benefits from converting brownfields to Greenfields as well. The International Economic Development Council is reported to have found that projects that provide greenspace more than double the value of surrounding properties. That increased property value adjacent to Greenspace is reported to be more than four times the increase in citywide property values. In addition, a federal study is reported to have found that when quality of life issues, such as increased greenspace, are ignored or are a low priority, a municipality has a more difficult time attracting and retaining business and the rate of economic growth is lowered. [14]

Petroleum Brownfield Site Identification, Assessment and Remediation.

We now know what a Petroleum Brownfield site is, and how it can affect the health of the local populace, what next? Well, we need to find sites available for remediation, once we locate a site and find out it is suitable and on the market for remediation either with a government/EPA grant or private investments we need to think about what we will do with the land. This is something to consider before starting work.

Options for Remediation of Petroleum Brownfield Sites

  1. Car Park or flat unused ground.

  2. Industrial Estates and shopping malls.

  3. Housing.

  4. Greenfield Site.

Depending on the new purpose for the site will determine the level of remediation required, and there is a lot to consider. Many factors will determine this, such as the level of funding, the space available, what a local community really need and how to go about it.

Traditional methods involve removing the contaminated soils to landfill sites where there is still a contamination risk of pollutants leaching into the surrounding areas and into the groundwater. It is costly and not always convenient on both timescale and budget. It is also not the best method because new soils and infill need to be brought into the area, however, what if there was a way to keep the original soils there and to remediate the entire pollution problem?

At Custom Enzymes we have developed an enzymatic solution that uses both enzymes and bacteria to digest oils, we currently use it for oil spills, and it is adaptable for brownfield sites, the theory is to drill equidistant holes in the soil and inject the solution so that it may spread within the soil digesting the hydrocarbon molecules wherever it finds them.

So how do enzymes work?

Infinita Biotech say it best:

  1. All Enzymes have unique characteristics. They can vary depending on their specification.

  2. Enzymes mostly are highly efficient, and they come up with great catalytic powers. This means they can transform almost 1000 and sometimes even up to 10,000 substrate particles into products every second. Enzymes can also easily proceed 108 times quicker as compared to the uncatalyzed reaction. Enzymes never impact the equilibrium constant even if there is a surge in the concentration of the substrate in the product. You will need only a small fraction of enzymes under normal situations for catalysing and speeding up the chemical reaction.

  3. Enzymes never change during a chemical reaction.

  4. Sometimes Amino acid residue of the enzyme can break, or it can sometimes even lead to the genesis of covalent bonds with the substrate. But enzymes can restructure those bonds that break and separate them with substrates.

  5. You can regulate enzymes in different ways. However, the functioning of catalysts cannot be controlled. Most of the time, activators, as well as coenzymes, are essential for enzyme catalysis.

This process is beneficial in increasing the potency and effectiveness of the enzymes because of the existence of any weak bond in the middle of the enzyme and the metal ion. In addition to this, certain molecules may inhibit the function of enzymes. They do so by modifying their regular shape and size. Usage of different drugs is closely related to their working as an enzyme inhibitor.

  1. The efficiency and impact of enzyme catalysts can be maximum when it is at its ideal temperature. An increase, as well as a decrease in the ideal optimum temperature, could lead to a reduction in the catalytic functioning.

  2. The catalysis of an enzyme can also differ depending upon the PH level of the mixture—enzyme functions at its maximum capability when the PH is in the middle range of 5 to 7.

  3. The catalytic functioning of the enzyme can be reduced by using competitive inhibitors, non-competitive inhibitors, as well as irreversible inhibitors. The competitive inhibitors are ones that are tied to the active place of the enzyme. The non-competitive inhibitors are those that can get attached to any other site of the enzyme rather than the active place. All of these enable the enzymes to be less active and sometimes even inactive. The irreversible inhibitors are those that bond with the enzyme itself to make it inactive.

  4. Most people do not know this, but the enzymes can sometimes also work reversely. This means that enzymes do not regulate the direction of the chemical reaction. Enzymes only work to accelerate the rate of reaction till it achieves equilibrium.

Since we understand the nature and characteristics of enzymes, it can become an easy task to understand the characteristics of enzyme catalysis. Enzyme catalysis is a simple process that leads to an increase in the rate of enzymes. Most enzymes are made up of proteins. But enzymes can also include non-protein components like metal ions and specialized organic molecules as a cofactor. Most cofactors are vitamins, and they are usually linked to their usage in the catalysis of biological processes at the time of metabolism. Catalysis of biochemical reactions is quite important as most metabolically essential reactions have a meagre rate when they do not have the catalysing capability.


  1. Transformation of glucose to ethanol in the presence of zymase enzymes

  2. The hydrolysis process of urea in the presence of urease enzyme is another major example of enzyme catalysis.

  3. The Hydrolysis process of starch to maltose in the presence of an enzyme called Maltase.

  4. In our stomach, pepsin converts proteins to peptides. [15]

So, with all this information at hand, you can see how the benefits of using enzymes far outweigh the costs of not using enzymes. For more information please contact.

We will be happy to talk through enzymatic solutions, applications, delivery methods and remediation with enzymes, thank you for reading I look forward to your responses and suggestions.

















Robert Furness 28th June 2021


bottom of page