TPH Impacted Groundwater- SM/MNA
Location: North Central Indiana
Scope: Groundwater remediation through stability monitoring and monitored natural attenuation
The site is located within a designated sole surface aquifer area and further complicated by the presence of a nearby municipal well field. Although the published wellhead protection plan indicated the site is outside the 5-year capture zone of the well field, site specific hydrogeology clearly demonstrates that groundwater at the site is influenced by the pumping station.
The investigation results indicated petroleum related constituents present in the groundwater at maximum solubility concentrations, although no free phase petroleum product was observed. Delineation of the impairment indicated concentrations of chemicals of concern at levels exceeding industrial default closure concentrations in groundwater over a large aerial extent, yet not extending beyond the downgradient property boundary.
TecServ used groundwater contaminant fate and transport models applying conservative assumptions that demonstrated acceptable risk exposure in regard to impacting the municipal well field. Ongoing groundwater monitoring is being conducted to demonstrate that the impact is stable and not migrating toward the municipal well field. It is anticipated that no further remedial action will be required to close the incident.