Polishing of BTEX And MTBE Service Station Closure Effort - Case Study

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Courtesy of EN Rx

Aservice station in Montgomery County, Pa underwent a hydro- geologic re-assessment in March 2002. The contaminants at the site included BTEX constituents; MTBE, a fuel oxygenate; Isopropyl-benzene; and Napthalene. These Contaminants of Concern (COC’s) were not degrading rapidly through natural attenuation and direct oxidation in the form of Fenton’s Reagent.

Initially, several Fenton’s Reagent applications were applied through permanently installed injection points, with little effect due to minimal migration through clay matrix. Hydraulic conductivity at the site was in the range of 10-6 cm/sec. These non-effective Fenton’s applications prompted a different approach. Due to its attributes, EN Rx Reagent was selected for use.

EN Rx Reagent was applied to the sub-surface utilizing the same permanently installed injection points that were used for the Fenton’s injections. EN Rx Reagent was applied at very low pressure, less than 8 psig. The PA DEP required 8 consecutive quarterly sampling events to demonstrate attainment of this site. The attainment well was MW-4. The 8 sampling events are listed below. Site received closure status from PADEP.

The following table shows sustained results over time. No heat production, off-gassing or water agitation was observable in the field. Contaminants are listed in ug/L.

Parameter

Baseline

1st Quarter Attainment

2nd Quarter Attainment

3rd Quarter Attainment

4th Quarter Attainment

5th Quarter Attainment

6th Quarter Attainment

7th Quarter Attainment

8th Quarter Attainment

Benzene

170

1.1

ND

ND

5

3.2

ND

ND

ND

Toluene

18

ND

ND

ND

ND

2.5

ND

ND

ND

Ethylbenzene

7.3

ND

ND

ND

ND

ND

ND

ND

ND

Xylenes

7.9

ND

ND

ND

ND

ND

ND

ND

ND

MTBE

460

7.6

ND

ND

ND

9

ND

ND

ND

Isopropylbenzene

47

ND

ND

ND

2.2

ND

ND

ND

ND

Napthalene

7.8

ND

ND

ND

ND

ND

ND

ND

ND

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