Zenshine Urban Soils Study

In 2023, Zenshine Community Garden volunteers began exploring garden expansion opportunities. In addition to plans for an apiary, pollinator gardens, and meadow restoration, Zenshine Community Garden aspires to add a community fruit orchard to the site. This expansion project, supported by Tree Pittsburgh’s Giving Grove program partnership, will allow for the planting of approximately 10 fruit trees at the garden site. Prior to this project, all growing at Zenshine Community Garden had been in raised beds. Because this orchard expansion would be the first in-ground growing at Zenshine Community Garden, garden volunteers reached out to ACCD’s Urban Soils Program for soil lead screening services to identify the presence of heavy metals in the native soil, learn more about risk associated with soil lead levels while gardening, and implement soil lead remediation strategies if necessary. 

In August 2023, ACCD staff visited the Zenshine Community garden to meet with garden volunteers, demonstrate soil sample procedure, and collect soil samples. The orchard planting site measured 40 ft x 50 ft. This site was broken down into 20 smaller 10 ft x 10 ft sample squares, with a representative sample taken from each. These samples were then processed at ACCD’s in-office laboratory space. Processing includes the drying, grinding, and sieving of each individual soil sample. Once processed, soil samples were ready for analysis with the XRF spectrometer. This elemental analysis revealed approximate lead content in terms of part per million (PPM). Each sample is analyzed, and results were mapped using satellite imagery of the Zenshine Community Garden site. A site average for lead content is also created by averaging the individual sample results together. 

Analysis of the Zenshine Community Garden orchard expansion site yielded an average site lead content of 141.15 PPM Pb. Interpreting soil lead results can be challenging and there is no single threshold that defines acceptable levels of lead in soil. ACCD utilizes a set of guidelines developed in consultation with industry experts to indicate the degree of risk associated with various soil lead concentrations. The average site lead content for Zenshine Community Garden’s future orchard planting falls within the threshold for “Very Low Risk," the range of lowest risk that does allow for in-ground gardening, but because lead contamination occurs on a continuum (depends on level frequency, and duration of exposure), it will be important to implement “clean hands policy” when working in the orchard space by washing hands throughly before and after gardening and always wearing fresh, clean gloves. This will futher minimize exposure to lead contamination through clothing and contact.  

The Urban Soils Program focuses on lead and contaminant research, soil testing outreach and technical assistance. ACCD’s expertise also extends to urban farm and garden resources, policy planning and networking.