PHYTOREMEDIATION RESEARCH CASE STUDY
Project Name: Pinehurst Hotel Dry Cleaners (ATC 2013) (Sand Creek 2013)
Location: Pinehurst, North Carolina
Consultants/ Scientists: Sand Creek Consultants, Wisconsin and ATC Associates, North Carolina
Date installed: 2010
Species Installed: Hybrid Poplars (Poplar spp.) and Willows (Salix spp.) were installed downgradient of the source area to prevent migration of the contaminant plume.
Area A – Hybrid poplars planted on 3.2 x 2.4 meter (8 x 6 foot) grid spacing
Area B – Hybrid poplars and willows planted between existing Magnolia trees
Amendments: Iron (Zero Valent) was injected into the source area to help breakdown pollutants in the most contaminated areas. Phytoremediation was not used in the source area: only downgradient to control the migrating contaminant plume. Pine straw and turf grass were utilized for weed control within the phytoremediation planting.
Contaminants: PCE, TCE, Benzene, Xylenes
Target Media & Depth: Groundwater at 4 meters (13.5 foot) depth
Pinehurst Hotel Cleaners was a dry cleaning and laundry facility for the former Pinehurst Hotel and operated from the 1930’s until the 1970’s. Contamination was identified during a due diligence assessment on an adjacent property. The property owner registered the site with North Carolina’s Dry-cleaning Solvent Cleanup Act (DSCA) Program in 2001.
Beginning in 2008, 750 tons of contaminated soil were excavated at the plume source and treated on site using a mobile steam distillation unit. Additionally, zero valent iron was added near the plume source to help breakdown contaminants. A phytotechnology installation consisting of hybrid Poplar and Willow plantings was installed on two sites in 2010 further down gradient on the plume, a deep-planted zone where groundwater was 18 feet below grade, and a shallow-planted zone where groundwater was less than 3 feet below grade.
These phytotechnology plantings provided hydraulic control of the plume and prevented discharge of dry cleaning solvents to a nearby surface water stream. The deep planting species were hybrid poplar, installed between the source area and the stream, and required planting the 20-foot trees into deep boreholes to access groundwater. The shallow plantings were hybrid willow, and were installed as buffers along the banks of the surface water stream. Phytotechnology approaches were utilized due to their low cost and to comply with stakeholder desires for a green and environmentally friendly remediation solution. Today the plume is stable and surface water impacts have been successfully mitigated.