API 4668 : 1998

DELINEATION AND CHARACTERIZATION OF THE BORDEN MTBE PLUME: AN EVALUATION OF EIGHT YEARS OF NATURAL ATTENUATION PROCESSES

American Petroleum Institute

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Executive Summary
1. Introduction
2. The MTBE Field Experiment at CFB Borden, Ontario
3. Methods of Groundwater Sampling and Analysis
4. Sampling Strategy for the 1995-96 Sampling Rounds
5. The 1996 Sampling Results
     5.1.MTBE
        5.1.1 MTBE Coarse Grid Sampling Results
        5.1.2 MTBE Fine Grid Sampling Results
        5.1.3 Additional MTBE Sampling Results
     5.2.Tert-Butyl Alcohol (TBA) and Tert-Butyl Formate (TBF)
     5.3 Chloride
     5.4 BTEX
     5.5 Oxygen
     5.6 Sulfate
     5.7 Ammonia
6. Summary and Discussion
7. Future Work
References
Appendix A
Preliminary Modeling and Results of the 1995 Sampling Round
Appendix B
Two-Dimensional Modeling Using Random Hydraulic Conductivity Fields
Determination of the Optimal Grid Spacing Using Geostatistical Methods
List of Figures
2-1. Plan view position of the MTBE plume (upper) and the chloride plume
      (lower) 476 days after injection
2-2. Calculations of depth integrated concentrations using vertically
      distributed concentrations at a single sampling location
2-3. Mass of MTBE and C1 in the MTBE slug over the initial 476 days of
      snapshot monitoring
2-4. Mass of selected BTEX compounds in the MTBE slug over the initial
      476 days of snapshot monitoring
2-5. Corrected mass of MTBE and C1 in the MTBE slug over the initial 476
      days of snapshot monitoring
4-1. Cross section of the Borden field site with the injection area
      (source), the last sampling snapshot at 476 days and the
      anticipated plume location 7 years after injection
4-2. MTBE sampling results from the November 1995 sampling round with
      peak concentrations at each location in ug/L
4-3. Location of a conservative MTBE plume 2920 days after injection,
      based on modeling three separate realizations using Borden aquifer
      hydraulic properties
4-4. The anticipated MTBE plume 2920 days after injection with depth
      integrated concentrations in mg/m2
4-5. Sampling locations for the coarse grid sampling round in 1996
5-1. Sampling locations with depth integrated MTBE concentrations
      (mg/m2) for the coarse grid sampling round
5-2. Sampling locations with depth integrated MTBE concentrations
      (mg/m2) for the fine grid sampling round
5-3. Additional bundle piezometers installed along transect A-A'
      at locations B, C and D
5-4. Examples of MTBE depth profiles for the transect A-A'
List of Figures
5-5. Sampling locations with depth integrated total BTEX concentrations
      (mg/m2) for the fine grid sampling round
5-6. Dissolved oxygen concentrations (mg/L) at various depths at
      locations B, C and D using bundle piezometers
5-7. Examples of MTBE/Sulfate depth profiles for the transect A-A'
5-8. Sampling locations with depth integrated ammonia concentrations
      (g/m2) for the fine grid sampling round
6-1. Schematic cross section of the vertical MTBE concentration
      distribution from injection until 1996
6-2. Depth integrated and time corrected MTBE concentrations (mg/m2)
      for all sampling rounds
6-3. MTBE field mass estimates with the initial sampling rounds
      (up to 476 days) and the final sampling round about 8 years
      (3000 days) after injection
List of Tables
2-1. Mass and concentration of solutes initially injected and mass
      determined by snapshot sampling at later times
4-1. Minimum mass recovered from a simulated MTBE plume using different
      sampling grid designs

Abstract

A natural gradient tracer test was taken in 1988 in the Canada Forces Base Borden in shallow sand aquifer. This was to assess the fate of MTBE (methyl-tertiary-butyl ether) plume added to the aquifer. In 1995/96 a groundwater sampling program was performed to define the mass of MTBE still present in the acquifer.