A research and education garden to clean up contaminated soil at la Finca Del Sur, South Bronx (138th Street and Grand Concourse)

by Kaja Kühl, youarethecity.com

This project aims to increase citizen knowledge about soil contamination and how to remediate it in a slow but low-cost process. In a test garden in the South Bronx, visitors will be able to see phytoremediation plants at work together with an educational installation to explain and monitor the process.

In New York City, 7.1% of the land is currently vacant. This equals 11,000 acres of underutilized land, roughly the size of Manhattan. Much of it is possibly contaminated by previous industrial uses on the site or leftover building materials, especially lead-based paint. Utilizing this land for food production, recreation or housing is not safe unless, the soil and groundwater are free of toxins.

Remediation – typically in the form of excavation of contaminated soil- is costly. Instead, many of these properties lie vacant for years, underutilized and toxic; their value dampened by sights of abandonment and potential contamination.

La Finca del Sur is one such site, tugged between the Major Deegan Expressway and Metro North railway tracks. In 2009, a group of women began to transform this abandoned site into an urban farm. The soil is contaminated, so plants are grown in raised beds with plastic sheeting separating them from the contaminated soil below. A portion of the land, which showed the highest levels of contamination was left untouched.

In collaboration with the farmers at La Finca, we are proposing a research and education garden on this portion of the land, where selected plants will remove heavy metals from the soil through phytoremediation.

By harnessing the natural capabilities of plants you can remediate toxic soils, groundwater, surface water, and sediments. Phytoremediation is a low-cost alternative to traditional brownfield remediation. Instead of removing tons of toxic soil and filling the site with new clean soil, plants remove contaminants from the soil and store it within their plant tissue. Contaminants successfully removed in field studies have included heavy metals, radionuclides, chlorinated solvents, petroleum hydrocarbons, polychlorinated biphenyls (PCBs), pesticides and explosives.

In this particular site, high levels of lead, chromium, cadmium and arsenic are found in the soil. The test garden will contain Indian mustard, alpine pennycress, Chinese Brake Fern and sunflowers, all known to have the ability to accumulate these contaminants. In conjunction with these plants, we will design educational markers, to be placed throughout the garden. The markers explain the process of phytoremediation to visitors and visualize the test results at each of their location. They will be updated with each new test phase and allow farmers to track the progress of this experiment.

The project will be accompanied with a series of public tours / events at the farm during the summer months of 2011 and 2012 and a field guide that offers a step-by-step instruction, how to clean up your own lot.