Brown 2 Green Associates – from dirty old acres to healthy new homes

Brown 2 Green Associates – from dirty old acres to healthy new homes

The UK needs more development land. Turning tired brownfield sites into attractive and clean greenfield plots is good then? Yes … providing they are, literally, safe to swallow! Bioavailability defines how much of a contaminant is available that can be absorbed by a healthy human body. As I would like to explain, this is about to become a crucial regeneration metric.

It is widely recognised that in Britain, compared to other European countries, millions of much-needed homes that should be on the housing market are missing. Closing this bricks and mortar gap so that a new generation of young people can look forward to home-ownership is a national priority.

But there is another problem.

The UK is also short of pre-used brownfield land which can be recycled and reused for residential developments. Or more accurately, we are short of clean and safe sites that meet strict planning conditions.

Brown 2 Green Associates (

This is where – as a new member of the Enzygo ( nationwide group of businesses – we can help to make a difference. And this is why.

Brown 2 Green’s contaminated land, geotechnical engineering, environmental property and planning services are designed to identify, investigate, mitigate, restore and return land in poor condition to the marketplace. All projects are director-led from our base near Cambridge.

Enzygo, meanwhile, is a rapidly-growing independent UK multi-disciplinary environmental and planning consultancy group of companies based in Sheffield, Bristol, Manchester and Cardiff.

By combining our professional resources, we can support the urgent new drive to provide the homes and infrastructure the UK needs for a sustainable economic recovery and long-term prosperity.

Integrated strengths, goals, and solutions

To understand how these factors come together, I describe below why remediating brownfield land is important, its political and regulatory drivers – and why the knowledge of ‘bioavailability’ means more targeted, effective and less costly remediation.

I also show how the joined-up strengths of Brown 2 Green and Enzygo support this, include several brief case examples, summarise the services we offer, and end with some interesting statistics.

New plans for the North and South

In July 2023, levelling up secretary Michael Gove and the Prime Minister announced plans to regenerate brownfield sites for housing and more homes in cities (

The South East – where we work extensively – has the UK’s largest number of brownfield plots, followed by London. This region has many old commercial, business and industrial sites that need transforming for real homes.

However, we are also active in the North where levelling up is a new priority and we are working on a large-scale hydrogeological assessment for a residential development near Tadcaster and a contaminated land assessment of a site in Stoke-on-Trent.

A levelled up playing field?

The Department for Levelling Up, Housing and Communities said in January thousands of new homes will be built on ‘disused and unloved’ brownfield land with £60 million support from its Brownfield Land Release Fund 2 to ‘bring neglected urban areas back into use, support regeneration projects and boost local economies’.

This funding is meant to help deliver 5,800 new homes by March 2027, plus circa 18,000 new housing and construction sector jobs and support for thousands of first-time buyers (

In July 2022, the department also announced plans to create 17,000 new homes on recovered derelict sites through a new £180 million fund (

Regulatory framework

The regulatory driver for brown to green is the National Planning Policy Framework (NPPF)–2). This sets out government’s planning policies for England and how these should be applied by local authorities.

NPPF encourages the re-use of brownfield sites and says planning decisions should ensure sites are suitable for their proposed use, taking into account ground conditions and pollution. It requires site investigation by a competent person(s).

Bioavailability – making soils safer

Because soil pollution has historical been a problem, the detailed understanding of contaminants levels, and the assessment of bioavailability of these contaminants, now gives us a greater understanding of the level of risk posed, and provides a more cost-effective approach to remediation.

It might be helpful if I explain what bioavailability means. It refers to the percentage of a contaminant that is present which could enter the bloodstream from ingestion of contaminated soil. All generic assessment criteria that are currently used are based on 100% of the contaminant being taken up by the body. We now know this is not so. In fact, levels are much lower.

The new ‘ISO/DIS 8259: Soil quality – Bioaccessibility of organic and inorganic pollutants from contaminated soil and soil-like material’ ( standard to improve risk assessment, particularly for organic compounds, is undergoing its final  review.

New documentation now exists; however, the test methodology is still to be signed-off by an appropriate authoritative body. We are monitoring this closely.

Hard to swallow

Old combustion products like ash, coal and tarmac can be carcinogenic. But when swallowed, most pass straight through the body. Having a meaningful official metric will allow us to tailor site-specific risk assessment resulting in remediation much closer to contamination problems we identify.  In turn, this means we can achieve higher remediation targets while reducing unnecessary costly and disruptive interventions.

Brown 2 Green + Enzygo team strengths

As mentioned above, our strategic goal is expanding the group’s capabilities and geographical presence. Particularly important is Brown 2 Green’s expertise in environmental and contamination assessment. This bolsters Enzygo’s existing geotechnical assessment and design skills.

Immediate benefits to Brown 2 Green clients is access to Enzygo’s experience in planning, hydrology and drainage, permitting and regulation, plus landscape, ecology, transport, geo-environmental and hydrogeology, noise and vibration, air quality and arboriculture.

The result is that we can now provide the local knowledge needed for the best outcomes across the UK, plus creative, integrated and cost-effective solutions that maximise development site potential.

Who we work with

As a point of interest, we work frequently with: – residential and commercial developers, planners, structural engineers, highway engineers, architects, construction project managers, chartered surveyors, waste management companies, energy and utility companies and contractors.

We also liaise closely with: – regulatory authorities, legal and financial institutes, property investment companies, property management firms, and loss adjustors.

Leading the way with lead – case examples

Although the ‘polluter pays’ principle may apply, contamination often dates back not only tens but even hundreds of years, which means that the offender has long since disappeared.

The range of site types and sizes, plus the contaminants we are asked to deal with, are extensive. Meeting quality standards for metals is a key requirement. A current example is a large former horticultural property in East Anglia where high levels of lead were detected across the whole site.

We often find lead buckshot in the ground, or in this case it was suspected to be from lead-containing paint used on the glasshouses. Our goal is to ensure the site is made safe for residential use.  The use of bioavailability testing demonstrated that only 5% of the lead present was bioavailable.  The adoption of site-specific risk assessment resulted in a significant reduction in the remediation that was required, and a significant saving for the client.

Another challenge, particularly around the highly rural edge of London, is asbestos. A recent example was the remediation of a former stables which made ground containing refractory bricks, clinker and fibrous asbestos was originally brought in from a now closed foundry.

Asbestos removal is highly regulated, with asbestos being classified as Hazardous Waste.  Our responsibility was to verify complete treatment which consisted of sorting of the material to create a series of waste streams and reduce the volume of waste that would be classified as Hazardous.

Large-scale ex-industrial

Run-down industrial estates that cover extensive land-parcels are typical projects for us too. These types of sites may have a large number of commercial and industrial uses that are classified as contamination sources. The storage of old fluids associated with car repair workshops or solvents used for degreasing are common issue. We also deal with the legacies of other nefarious commercial activities that took place well away from the public eye!

These sites can be up to half a kilometer square (400m x 500m). In many cases, we are asked for full site investigations and remediation strategies.

Assessment of risk to controlled waters is frequently an issue. Based near London, where a significant proportion of the drinking water is sources from groundwater, protection of the quality is essential. We have also conducted investigations with associated risk assessment for hydrocarbon, agro-chemicals and solvent impact to controlled waters. Former filling stations with underground storage tanks, former laundries, derelict farm yards, and forgotten landfill sites, are bread and butter assignments too.

Our services – details are shown at

Before looking at some interesting brownfield statistics, I would like to quickly outline our specific services. They include: –

Contaminated land services – We provide assessments of geo-environmental conditions and the potential liabilities associated with contaminated land – all our service also include a full understanding of the data needed for risk assessments and remedial design.

Geotechnical engineering services – Our teams also assess geo-environmental conditions and provide professional advice and analysis for designing foundation solutions and earthworks.

Environmental property services  Britain’s industrial heritage has created environmental and geotechnical risks with financial or legal liabilities that can affect the value and viability of investments.

A permit or authorisation for redevelopment may be needed to show that a polluting process has stopped and the site poses no future risk to human health and the environment.

We can identify any potential liabilities inherited in purchasing a site, and review vendor pack information to pinpoint possible abnormal costs that could be incurred during site development.

Utility route geological feasibility studies – full details of this specialist area are on the website.

Environmental planning services – we work closely with other land developments consultants to provide project continuity and, through Enzygo, can help clients with other planning services.

These include:- ecology, air quality monitoring and modelling; noise assessments; project management of Japanese Knotweed eradication; highway, traffic, transportation assessment; flood risk and urban drainage; sustainability and renewable energy; and asbestos management.

Specific specialist services

Where we identify a specific need, we also carry out: – Phase 1 geo-environmental desk studies; Phase 2 intrusive site investigations; detailed quantitative risk assessments; remediation design, project management and validation; regulatory liaison and completion; plus CL:AIRE Definition of Waste: Development Industry Code of Practice and Material Management Plans (Dow: CoP).

Facts and figures footnote

It is worth noting that in 1800 only 10% of the English population lived in towns and cities. ( This has risen to 90% which makes England the world’s third most densely populated major country – the population is projected to rise to 62 million by 2035.

Studies as far back as 2011, warned of a housing black hole, with a 750,000 homes shortfall by 2025. This is what we now face (

Updated warning

However, the Campaign to Protect Rural England’s (CPRE) 2022 state of brownfield report says the availability of previously developed land is growing across England. It found that more than 1.2 million homes could be built on 23,000 sites over more than 27,000 brownfield hectares (

It adds that tens of thousands of hectares of prime brownfield sites are waiting to be redeveloped, with old industrial heartlands in the north of England the worst for unused brownfield sites.

An analysis of 344 brownfield registers by Environment Analyst released in January 2023 showed a 6% increase in available brownfield land covering 27,342ha (67,563 acres), compared to 21,500 sites on 26,250 ha in 2021, again with the capacity to provide 1.2 million homes (

Up and down

However, the proportion of new residential addresses created on previously developed land fell by 12% year-on-year in 2021-22 to 54%, after a 12% rise the year before, according to figures released in November 2022 ( Government figures in ‘Dataset: Brownfield land’ can be seen at

More help and information

Please feel free to contact me directly if you would like to discuss any of the issues above.

Philip Miles – Director at Brown 2 Green Associates (part of The Enzygo Group).

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