Petroleum Hydrocarbons at a Former Gas Station in Tallahassee, FL

Petroleum Hydrocarbons at a Former Gas Station in Tallahassee, FL

Site Overview

Evidence of petroleum impacts was initially reported on May 26, 1988 based on elevated vapor concentrations from monitoring wells at a former Circle K retail gas station now operating as a used car dealer. A second discharge was reported on December 26, 1992, when approximately 100 gallons of unleaded fuel was released during a fuel delivery. The 1988 discharge was deemed eligible for the Florida Early Detection Incentive (EDI) Program and the 1992 discharge was granted eligibility in the Petroleum Liability Restoration Insurance Program (PLRIP). Phillips 66, ATC Group Services, Inc., and the Florida Department of Environmental Protection (FDEP) entered into a Performance Based Advanced Cleanup Program Agreement to achieve site closure for this site as part of a Preapproved Advanced Cleanup Bundle with 19 other sites (20 total).

A Remedial Action Plan (RAP) was submitted on January 15, 2016 and approved on February 5, 2016. The RAP outlined a Groundwater Recovery system with a BIOX® chemical injection component. Only the chemical injection portion of the approved design was implemented due to complications while drilling the proposed recovery wells. The BIOX® injection campaign included a total of approximately 1,610 gallons of amendment fluids distributed among 23 Direct Push injection points.

Project Specifications

  • Contaminants: BTEX, MTBE, Naphthalene, 1-Methylnaphthalene, 2-Methylnaphthalene
  • Contaminated Media: Soil and Groundwater
  • Treatment Area: 810 square feet
  • Soil Type: Sand and silty sand 

Project Results

Groundwater sampling in January 2017 indicated 33% to 99.9% reduction of the petroleum contaminates of concern for the key wells. Confirmation sampling is on-going.

Analytical Results (ug/L)


Well ID




Cleanup Target


Pre-injection (April 2016)


Post-injection (January 2017)


% Red.

MW-56 Benzene 1 4.2 1.7 78.1
MW-57 Benzene 1 13 3.6 78.3
MW-64 BTEX + MTBE Group 111 968.6 35.51 Goal Met
MW-64 Naphthalene 14 200 0.22 Goal Met
MW-64 1-Methylnaphthalene 28 33 0.22 Goal Met
MW-64 2-Methylnaphthalene 28 38 0.22 Goal Met
MW-65 BTEX + MTBE Group 111 154.41 103.3 Goal Met
MW-65 Naphthalene 14 17 11 Goal Met



COC = Contaminant of Concern (i.e., Benzene, Toluene, etc.)

% Red. = % Reduction (see formula)

BTEX+MTBE Group = Sum of Benzene, Toluene, Ethylbenzene, Total Xylenes, & Methyl Tert-Butyl Ether (MTBE)

Naphthalene Group = Sum of Naphthalene, 1-Methylnaphthalene, & 2-Methylnaphthalene

If the contaminant was not detected, the method detection limit was used for calculation purposes.

% Reduction (KWi) = {1-[(Cmli-Ctl)/(Cbli-Ctl)]}*100


KWi = key well number i

Cmli = milestone measurement concentration of contaminant group in key well i

Ctl = target level concentration for contaminant group, and

Cbli = baseline concentration of contaminant group in key well i

Goal Met = Concentration of COC (or Group) was less than Cleanup Goal (i.e. calculation output was >100% Reduction).