Overview
Since the early the 1990’s, Water & Air scientists have completed a variety of environmental tasks at the former phosphate mine turned municipal landfill. The tasks included a geophysical assessment of landfill cells and buried materials and a contamination assessment and remediation of soil and groundwater. The area was affected by arsenic, petroleum products, industrial solvents and degreasers, and a variety of chemicals used in the phosphate mining industry. Water & Air was focused on a 28-acre portion of the mine affected by the contamination.
Task Summary
- Conducted a geophysical survey to identify the location of the former municipal landfill cells and other buried items from the former mining operation.
- Excavated areas where subsurface anomalies were identified by the geophysical survey.
- Determined groundwater elevation and flow in different water bearing zones beneath the site and adjacent properties and defined the seasonal groundwater table fluctuations.
- Measured the horizontal and vertical extent of halogenated and aromatic volatile organic compounds, Total Recoverable Petroleum Hydrocarbons (TRPH), and arsenic impacts in soil and groundwater.
- Developed and implemented Remedial Action Plans and a Source Removal Plan for petroleum impacts.
- Performed in-situ chemical injection to reduce petroleum impacts underneath a rail spur.
- Installed monitoring well clusters and double-cased aquifer wells and conducted confirmatory soil testing.
Results
The groundwater test results indicated that the remaining concentrations of contaminants attenuated over time and did not require remediation. Quarterly groundwater monitoring at more than 40 surficial and intermediate aquifer monitoring wells was performed for five (5) years to assess the contamination concentrations and vertical and lateral extent of contamination impacts. As a result of the work, less than one (1) acre remains impacted due to secondary water standards for Total Dissolved Solids (TDS) and nitrates. This area is in the process of obtaining a Restrictive Covenant, while the remainder of the property will enter into a Site Rehabilitation Completion Order (SRCO). As a result, the client was able to develop most of the site for use as citrus groves and cattle pasture.
