Site Characterization of a Vehicle Maintenance Garage

Survey Summary

Location: Northeastern US
Property: Vehicle Maintenance Garage
Objective: Optimize placement of monitoring wells

• USTs supsected of leaking fuels
• BTEX and MtBE impact delineated
• GORE™ Survey and groundwater data compared well

Survey Objective

Located within a residential area, this commercial site was a suspected source of groundwater contamination, possibly the result of leaking fuels from USTs. The objective of this survey was to delineate a suspected BTEX plume from two 5,000 gal. USTs, and to identify the optimum placement of monitoring wells.

Site Background & Geology

• Vehicle maintenance garage, Northeastern US
• 18,000 sq. ft. L-shaped survey
• Silty clays
• Groundwater depth: 10 - 20 ft.; apparent southerly flow

GORE™ Survey

• 27 GORE™ Modules
• Random grid, avg. 20 ft. spacing; 3 – 4 ft. install deep
• 14-day exposure
• Modified EPA method 8260/8270 GC/MS analysis at Gore labs

Survey Results

The GORE™ Survey revealed the presence of two BTEX plumes (Fig. 1): one in an area of known USTs; the other, a less intense BTEX plume, in an area where an older UST was later identified. MtBE was also observed in the soil gas (Fig. 2), and appeared to “lead” the BTEX plume, as elevated levels were located away from the source at the time of the survey.

As a result of the GORE™ Survey, optimized installations sites were identified for five monitoring wells. Soil borings analyzed for BTEX yielded non-detectable levels. However, water quality data from the monitoring wells compared favorably with the GORE™ Survey (Fig. 1).

Survey Conclusions

The GORE™ Survey delineated the nature and extent of the subsurface impact by BTEX and other fuel-related compounds, efficiently and accurately. Placement of monitoring wells was optimized.

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