Shopping Mall – Georgia, USA

Site: Shopping Center – St. Albans, West Virginia
Constituents of Interest: Tetrachloroethylene, Trichloroethylene, 1,4-Dichlorobenzene, and Vinyl Chloride.
Lead Contractor: Innovative Environmental Technologies, Inc. (IET)

In August 2014, ERD-CH4 was added proximal to existing monitoring well MW-207s to treat groundwater at an active shopping mall in Georgia, USA that was impacted by PCE and its catabolites (TCE, DCE and VC) from a former dry cleaning operation. At the same time, the same amount of a standard ERD amendment (no methane inhibitors) was added proximal to existing monitoring well MW-4 which was located ca. 200 feet cross gradient.

Prior to amendment application, baseline groundwater analysis were conducted for dissolved methane and COIs.  Six weeks post application, groundwater samples were collected for similar analysis.  At that same time, analysis of the head space gases in MW-4 and MW-207s was conducted by Field Environmental Instruments (Pittsburgh, PA) using both a Thermo/Foxboro TVA-1000B PID/FID Analyzer (PID sensitive to 2,000 ppm CH4; FID sensitive to 50,000 ppm CH4) and a LandTec GEM5000 Landfill Gas (LFG) Meter (infrared detector calibrated to 15% methane). Well head space gases were analyzed from top of the well heads immediately upon opening the well caps with readings recorded every minute for 5 minutes.

As summarized in Table 2, the MW-4 (water depth 11.9 ft bgs; pressure 0.11 in)  treated with an ERD substrate only had over 30% CH4 in the headspace gas as measured by the GEM5000 LFG meter (note – TVA detectors exceeded their level of sensitivity and shut down).  By comparison, the well headspace gas in MW-207s (water depth 18 ft bgs; pressure 0.24 in) had only 0.5% CH4.

Table 2a.  Well Head Gas Analysis at a Former Dry Cleaner Site in Georgia (6 weeks post ERD application). 

Well

Location

CH4 PID (ppm)

CH4 FID

(ppm)

CH4 TGA

%

CO2

%

O2

%

Balance (N)

%

MW-4

 

 

 

 

 

 

0 min

297

>50,000

34.8

65.2

0.0

0.0

5 min

439

>50,000

35.6

61.0

0.2

3.2

MW-207s

 

 

 

 

 

 

0 min

82

Out of range

0.5

1.0

12.7

85.8

5 min

41

1,599

0.4

0.7

20.2

78.7

 

Table 2b.  Dissolved Gas Analysis at a Former Dry Cleaner Site in Georgia (Method RSK 175). 

Well

Location

Pre-injection

(ppm)

6 weeks Post-Injection

(ppm)

 

CH4

PCE

CH4

PCE

MW-4

13,700

170

 

 

MW-207s

 11.8

 1,200

 

 

 

 


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