Site Investigation, including Drone Deployment, for Property Redevelopment
The client, the Pennsylvania Department of Environmental Protection (PADEP), required an extensive site-wide soil investigation to develop a plan for site remediation to reuse this former landfill and scrap yard property as a public park. Constituents of concern included polychlorinated biphenyls (PCBs); metals, such as arsenic and lead; and petroleum compounds
PADEP contracted GES to complete site investigation activities, including surface-soil sampling/screening, aerial photography/mapping, vertical soil investigation, monitoring well installation, groundwater monitoring, and report preparation to assist in moving the site forward to remediation and reuse as a public park.
Prior to initiating the soil sampling activities, GES completed a small, unmanned aircraft system (sUAS or drone) flight to obtain current site features, baseline condition of the site, and to identify stressed vegetation. GES contracted a Professional Licensed Surveyor to survey ground control points to utilize for the aerial mapping and stake initial starting points for the surface-soil sampling grid.
During the initial surface-soil investigation activities, GES utilized Clor-N-Soil kits to complete field screening for PCBs. The use of these kits allowed for real-time field analysis to determine the most impacted locations, which dictated the soil samples submitted for laboratory analysis. In addition to screening/sampling for PCBs, GES also collected discrete soil samples from six-inch intervals within the first two feet of soil for semi-volatile organic compound (SVOC) analysis and homogenized composite samples for total metals. During the surface-soil investigation, 275 locations were screened/sampled for laboratory analysis, not including all quality assurance and duplicate samples.
GES evaluated the surface-soil analytical data and prepared tables for comparison of the results against the selected PA Act 2 Standards for the site. Additionally, several figures were generated to visually represent the spatial distribution of the PCB, metals, and SVOC impacts and PA Act 2 exceedances across the site.
GES and PADEP will be holding a meeting with the City of Nanticoke, PA, state government officials to discuss the path forward for the project site. Based on the initial surface-soil investigation results, the remediation of the site will be extensive and require significant capital expenditure for hazardous soil disposal.
During the preparation of the work plan, GES completed a cost analysis of utilizing hand tools and field personnel to conduct the surface-soil investigation versus mobilization of a subcontractor for installation of the soil borings via direct-push technologies. It was determined that GES’ labor, materials, and equipment costs would constitute a savings to the PADEP.
GES utilized Clor-N-Soil PCB screening kits to complete field screening and reduce the volume of samples submitted for laboratory analysis. GES completed a cost analysis and determined that the costs for laboratory analysis far exceeded the purchase of the screening kits. Additionally, GES completed field screening at six-inch intervals in each boring to determine the most likely location of SVOC impacts, thus submitting one sample from each boring versus multiple samples.
Via thorough and well-planned systematic surface-soil investigation efforts, GES developed an initial conceptual site model that aided the PADEP in assessing the magnitude and extent of the soil impacts at the site. The pre-planned, staged approach to the investigation helped to keep costs in check and allow time to discuss the next phase of the investigation.