EPA Superfund Site, Columbus, Mississippi
USGS Technical Assistance to Support U.S. EPA Feasibility Studies, Remedial Designs, and Remedial Actions at Kerr-McGee Chemical Corporation Superfund Site, Columbus, MS
Background
The Kerr-McGee Chemical Corporation Site at Columbus, MS is an approximately 90-acre site located near Columbus, MS (Figure 1). The site was used from the 1920s to 2003 to treat wood with creosote. Soil and groundwater contamination from these activities comprise Operable Units (OU) OU-3 (Former Plant Area, Figure 1) and OU-4 (Pine Yard, Figure 1).
Since 2020, the USGS has provided technical assistance at the Columbus Superfund site to include the design, installation, and monitoring of a pilot-scale phytoremediation system to address OU-3 and OU-4 groundwater contamination. Phytoremediation is a cost-effective remedial alternative that can be used to address contaminated soil and groundwater at some sites (Landmeyer 2011; Landmeyer and Effinger 2016). In brief, the pilot-scale phytoremediation system to be tested will include:
- Passive system of hybrid poplar trees planted in the ground to tap the contaminated water table (OU-3)
- Active system of hybrid poplar trees planted in the ground and irrigated with deeper contaminated groundwater pumped from an existing monitoring or recovery well (OU-4).
The performance of the pilot-scale systems will be fully assessed using methods to quantify the effect of the phytoremediation systems of the water budget and contaminant fate at each OU.
Tasks Completed During FY2021
Monitoring Well Installation
Fifteen new monitoring wells were installed, using USGS direct-push technologies, in OU-3, and 3 wells were installed inOU-4, during March 2021 (Figure 2). The wells were instrumented in July 2021 with pressure transducers to record diurnal and seasonal changes in groundwater levels caused by the trees.
Tree Planting
More than 2,000 hybrid poplar tree cuttings were planted at OU-3 and OU-4 between March and April 2021. Prior to planting, trenches were made across the site (Figure 3).
The cuttings were planted in the trenches and backfilled with clean topsoil (Figure 4).
The cuttings came out of dormancy and leafed out in April, not long after planting (Figure 5).
By July, the cuttings had grown, in some cases almost 6 ft tall (Figure 6).
Tree Monitoring
The height and diameter of each tree was measured in November 2021, after leaf drop (Figure 7). Some trees had grown as much as 12 feet in one growing season.
Tasks Planned for FY2022
During 2022, representative trees will be monitored for uptake of groundwater contaminants using in situ passive samplers (Landmeyer and Effinger, 2016). The water budget for OU-3 and OU-4 will be calculated using locally measured rainfall amounts and site-specific measurement and calculation of potential evapotranspiration (PET). This data will be evaluated along with groundwater-level fluctuations measured in representative wells located within and adjacent to the pilot-scale system. Moreover, real-time transpiration (sap flow) will be measured on representative planted and native trees. Changes in offsite groundwater flow caused by groundwater uptake of the trees will be evaluated using the gages as described above.
USGS Technical Assistance to Support U.S. EPA Feasibility Studies, Remedial Designs, and Remedial Actions at Kerr-McGee Chemical Corporation Superfund Site, Columbus, MS
Background
The Kerr-McGee Chemical Corporation Site at Columbus, MS is an approximately 90-acre site located near Columbus, MS (Figure 1). The site was used from the 1920s to 2003 to treat wood with creosote. Soil and groundwater contamination from these activities comprise Operable Units (OU) OU-3 (Former Plant Area, Figure 1) and OU-4 (Pine Yard, Figure 1).
Since 2020, the USGS has provided technical assistance at the Columbus Superfund site to include the design, installation, and monitoring of a pilot-scale phytoremediation system to address OU-3 and OU-4 groundwater contamination. Phytoremediation is a cost-effective remedial alternative that can be used to address contaminated soil and groundwater at some sites (Landmeyer 2011; Landmeyer and Effinger 2016). In brief, the pilot-scale phytoremediation system to be tested will include:
- Passive system of hybrid poplar trees planted in the ground to tap the contaminated water table (OU-3)
- Active system of hybrid poplar trees planted in the ground and irrigated with deeper contaminated groundwater pumped from an existing monitoring or recovery well (OU-4).
The performance of the pilot-scale systems will be fully assessed using methods to quantify the effect of the phytoremediation systems of the water budget and contaminant fate at each OU.
Tasks Completed During FY2021
Monitoring Well Installation
Fifteen new monitoring wells were installed, using USGS direct-push technologies, in OU-3, and 3 wells were installed inOU-4, during March 2021 (Figure 2). The wells were instrumented in July 2021 with pressure transducers to record diurnal and seasonal changes in groundwater levels caused by the trees.
Tree Planting
More than 2,000 hybrid poplar tree cuttings were planted at OU-3 and OU-4 between March and April 2021. Prior to planting, trenches were made across the site (Figure 3).
The cuttings were planted in the trenches and backfilled with clean topsoil (Figure 4).
The cuttings came out of dormancy and leafed out in April, not long after planting (Figure 5).
By July, the cuttings had grown, in some cases almost 6 ft tall (Figure 6).
Tree Monitoring
The height and diameter of each tree was measured in November 2021, after leaf drop (Figure 7). Some trees had grown as much as 12 feet in one growing season.
Tasks Planned for FY2022
During 2022, representative trees will be monitored for uptake of groundwater contaminants using in situ passive samplers (Landmeyer and Effinger, 2016). The water budget for OU-3 and OU-4 will be calculated using locally measured rainfall amounts and site-specific measurement and calculation of potential evapotranspiration (PET). This data will be evaluated along with groundwater-level fluctuations measured in representative wells located within and adjacent to the pilot-scale system. Moreover, real-time transpiration (sap flow) will be measured on representative planted and native trees. Changes in offsite groundwater flow caused by groundwater uptake of the trees will be evaluated using the gages as described above.