Soil Contamination and Brownfield Remediation: An Introduction

Soil contamination is common in urban areas and poses both a physical and economic problem for city planning and development. Soil contamination is the result of various human activities, including but not limited to construction, personal care products in sewage sludge, lead from traffic and highway runoff. A site with significant soil contamination is classified as a brownfield. The Environmental Protection Agency (EPA) estimates more than 450,000 brownfields exist in the United States. [1]

Compost is sometimes listed as part of the solution for contaminated soil, due to its ability to build soil, improve plant growth and potentially mitigate the impacts from pollutants.

Global Green is working on a project to assess strategies for incorporating compost use to address the soil contamination as part of urban planning.

Understanding how compost can be used for soil remediation must build from an understanding of how soil is contaminated in the first place, which existing methods are being used to remediate contaminated soil, and when off-site soil is used as a part of the project remediation.

Table.1 Common Sources of Soil Contamination[1]

Caption: Source: EPA Brownfields Program. Urban Agriculture and Soil Contamination[2]

Caption: Source: EPA Brownfields Program. Urban Agriculture and Soil Contamination[2]

What is brownfield?

Brownfield is a legal term for urban soil that is contaminated with hazardous waste or high levels of pollutants. The Environmental Protection Agency (EPA) defines a brownfield as a "real property, the expansion, redevelopment, or reuse of which may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant."[3] To clarify the standard and actual presence of contaminants on a "real property", the Columbia Center for New Media Teaching and Learning’s Brownfield Action explains that it must be “determined by a carefully planned investigation known as an environmental site assessment (ESA). The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980 made the purchaser of any real property liable for any contaminants on this property. CERCLA's retroactive liability has made the performance of an ESA a practical necessity for any potential buyer of property, who naturally does not want to assume liability for the cleanup of any contaminants found there.”[4] Following brownfield classification, an ESA determines the extent of actual or perceived contamination. Following the ESA, corrective actions are taken.

The brownfield clean-up and reinvestment process can increase local tax bases, facilitate job growth, utilize existing infrastructure, alleviate development pressures from undeveloped, open land, and both improve and protect the environment.[5] Therefore, brownfield remediation is an important endeavor for urban areas. To provide a more in-depth explanation, some common brownfield remediation methods are described below

Brownfield remediation methods

There are different types of soil remedies depending on the either contamination levels of a brownfield or the type of contaminations. The methods listed below are from McGill School of Environment and Green Building Alliance’s guide, which serves as a primer on soil contamination.

- Physical remediation techniques[6]

Point-source contamination removal: The removal of polluting pipes, tanks, or other objects.

Excavation: Physical removal of contaminated soil which is normally disposed of at a landfill. Excavation is accomplished with heavy machinery. New soil is needed after the excavation. There are cases where contaminated soil can be treated off-site, and returned to the project site, alleviating the need for new soil.

Immobilization:  For brownfields with heavy metal contamination in the groundwater, chemical processes are utilized to fix these metals to soil particles so that they cannot leach out.

Caption: Source: Wood et al (2016). Microorganisms in heavy metal bioremediation: strategies for applying microbial-community engineering to remediate soils.[7]

Caption: Source: Wood et al (2016). Microorganisms in heavy metal bioremediation: strategies for applying microbial-community engineering to remediate soils.[7]

Soil washing: Physical removal of contaminated soil, followed by treatment at a plant or off-site. After the contamination is removed through the treatment process, the soil can be deposited back into the ground.

Caption:  Source: Godheja et al (2017). Xenobiotic Compounds Present in Soil and Water: A Review on Remediation Strategies.[8]

Caption:  Source: Godheja et al (2017). Xenobiotic Compounds Present in Soil and Water: A Review on Remediation Strategies.[8]

Soil vapor extraction:  This method is used for soil contamination above the water table. It involves the installation of wells and pipes in the soil, through which soil contaminants are extracted in vapor form.

 Caption: Lockheed Soil Vapor Extraction.[9]

 Caption: Lockheed Soil Vapor Extraction.[9]

- Biological remediation techniques[10]

Microbial remediation: Utilizes microbes in degrading contaminants into a less toxic form. This technique can be very effective in the treatment of hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), pesticides, and polychlorinated biphenyls (PCBs).

Caption: Microbial Remediation[11]

Caption: Microbial Remediation[11]

Phytoremediation: A method of planting species that can degrade contaminants around their roots, or species that draw up contaminants from the soil into shoots and leaves, which must then be disposed of.

Phytoremediation. [12]

Phytoremediation. [12]

How can compost benefit brownfields?

Compost can be used in conjunction with some soil remediation methods. Since compost can help create new nutrient rich soil, it can be used to create a distance between the contaminated soil and the soil that is used on the surface. For example, the addition of compost can be used in a raised bed, in which the plant roots may not reach the contaminated soil. In soil contaminated with heavy metals, compost may dilute the absorption by plants However; compost cannot biodegrade inert materials such as metals, sand or concrete. Many brownfield remediation methods require using soil that is transported from an off-site location. Off-site soil becomes a “new soil” resource, and mixing compost with sediment or soil “fill” can create new soil. In looking for potential compost use applications, we first look at how soil is transported on and off-site and whether any off-site soil may fit for a blend containing compost.

We looked at a study conducted by: Contamination Land: Applications in Real Environments (CL:AIRE)*. They collaborated with the University of Surrey, University of Cambridge, Forest Research, The Waste Resource Application Program, and the Composting Association. The research tested plants’ growth in soils that have different compost application rate, and studied the leaching of metals from compost amended soils as well as performance and metal concentrations of other soil. While many soil clean up techniques remove contaminants, they also destroy other soil characteristics beneficial for plant growth. Soil amendment, including compost, is now an important characteristic in brownfield remediation.

Here is how the CL:AIRE study found that compost can benefit brownfield reclamation.[13]

●  Can be used as soil amendment; Improves growth for plants and vegetables.

●  Improves the vitality of soil through improving the soil fertility, increasing the water and nutrient holding capacity, stabilizing the soil pH, improving soil aeration and enhancing revegetation.

●  Immobilizes metals (even heavy metals) thereby breaking contaminant-receptor pathways and reducing the eco-toxicity of the contaminants.

* (CL:AIRE is a registered charity and resource that provides materials and services to all those involved in sustainable land reuse.)

Case Study

This case study of provides some evidence of the effectiveness of compost in the remediation of contaminated soil. Tooele Army Depot (TEAD) is an ammunition storage and manufacturing facility for the Army. Elevated levels (up to 20,000 mg/kg) of 2,4,6-TNT and RDX (a white solid chemical compound widely used as an explosive) have been detected in the surface and subsurface soils at this facility. The army has decided to undertake corrective action. Compost has been chosen by the Army as the remediation technology for TEAD. Treatability studies conducted several years ago concluded that each batch of contaminated soil could be composted to meet the corrective action goals (31 mg/kg for RDX and 86 mg/kg for 2,4,6-TNT) within 20 days, temperatures required by thermophilic bacteria for proper composting would be reached within three days and would remain so for more than 20 days.[14] High temperatures conducive to such bacteria have been shown to accelerate the degradation of some contaminants greatly. The compost, in this case, is used to build more soil, degrade contaminants, and dilute the overall amount of pollutants per unit of soil and thus meet the corrective action goals.

This example pertains to a military government application. As a next step, we are seeking to learn more about examples of state level brownfield programs and where compost is used in urban or suburban areas, including private properties.

Closure

Global Green is looking for case studies and technical advisors on if and how compost use can be part of the solution for brownfield remediation and reuse.

Please contact us at [email protected] to learn more and to get involved.


[1] Heinegg, A., Maragos, P., Mason, E., Rabinowicz, J., Straccini, G. and Walsh, H. (2000) Urban Agriculture and Soil Contamination, retrieved June 26 from http://alivebynature.com/pub/Louisville_UrbanAg_Soil_Contamination.pdf

[2] Heinegg, A., Maragos, P., Mason, E., Rabinowicz, J., Straccini, G. and Walsh, H. (2000) Urban Agriculture and Soil Contamination, retrieved June 26 from http://alivebynature.com/pub/Louisville_UrbanAg_Soil_Contamination.pdf

[3] EPA. (2017, Apr 28). Overview of the Brownfields Program. The United States Environmental Protection Agency Official Website. Retrieved June 18, 2017, from https://www.epa.gov/brownfields/overview-brownfields-program

[4] Columbia Center for New Media Teaching and Learning. What is a “brownfield”?. Columbia Center for New Media Teaching and Learning brownfields action simulation website. Retrieved June 26th, from

http://brownfieldaction.org/brownfieldaction/brownfield_basics

[5] EPA. (2017, Apr 28). Overview of the Brownfields Program. The United States Environmental Protection Agency Official Website. Retrieved June 18, 2017, from https://www.epa.gov/brownfields/overview-brownfields-program

[6]  McGill School of Environment. (2002). Introduction. McGill School of Environment Official Website.  Retrieved June 18, 2017, from http://mse-research.mcgill.ca/envr401_2002/brownfields/intro.html

[7] Jennifer L. Wood1, Wuxing Liu, Caixian Tang, Ashley E. Franks. (2016, June 7). Microorganisms in heavy metal bioremediation: strategies for applying microbial-community engineering to remediate soils.# Retrieved June 26, 2017 from http://www.aimspress.com/article/10.3934/bioeng.2016.2.211/fulltext.html

[8] Jai Godheja*, Shekhar SK, Sarfraj Ahmad Siddiqui and Modi DR. (2016, August 5). Xenobiotic Compounds Present in Soil and Water: A Review on Remediation Strategies.# Retrieved June 25, 2017 from https://www.omicsonline.org/open-access/xenobiotic-compounds-present-in-soil-and-water-a-review-onremediation-strategies-2161-0525-1000392.php?aid=77909

[9]  Murray Company Mechanical Contractors. Lockheed Soil Vapor Extraction.# Retrieved June 25, 2017 from http://murraycompany.com/lockheed-soil-vapor-extraction-system/

[10] Green Building Alliance. (2016). Brownfield Remediation.

Green Building Alliance Official Website. Retrieved June 18, 2017, from https://www.go-gba.org/resources/green-building-methods/brownfield-remediation/

[11] Konsep Bioremediasi (Gambar: hubpages.com)

[12] Retrieved June 26, 2017 from /www.biology-online.org/js/tiny_mce/plugins/imagemanager/files/boa001/phytoremediationf03.JPG

[13] R van Herwijnen, G Sellers, D Sinnett, AJ Moffat, TR Hutchings, A Al-Tabbaa and S Ouki. (2006, April). The Use of Compost in the Regeneration of Brownfield Land. CL:AIRE's SUBR:IM bulletin, 10. Retrieved June 16, 2017, from, https://www.forestry.gov.uk/pdf/subrim_bulletin_10.pdf/$FILE/subrim_bulletin_10.pdf

[14] Craig Coker. (2016, Dec. 14th). Environmental Remediation By Composting. BioCycle Website. Retrieved June 23, 2017, from

https://www.biocycle.net/2006/12/14/environmental-remediation-by-composting/