AWWA ACE61600

Three sources of contamination have resulted in groundwater qualityimpacts at the New Mexico Department of Transportation (NMDOT) Las Vegas ServiceCenter in Las Vegas, New Mexico. Leaking underground storage tanks, leakingdistribution piping, and formerly unlined, salted cinder storage have contaminatedgroundwater with petroleum hydrocarbons, 1,1,1-trichloroethane (TCA), and totaldissolved solids (TDS), respectively. The plumes are distinct at the source areas, butcommingle downgradient. The low permeability of the shallow water-bearing zonemakes groundwater extraction via wells impractical due to low production rates. Thenature of the commingled contaminants and low permeability of the subsurface, wereconsidered in the selection of an extraction and ex-situ treatment remedy forcontaminated groundwater. Because a trench has greater access to contaminant flowpathways (fractures and bedding planes) than a single, or multiple wells, trench-baseddual phase extraction (DPE) was piloted to evaluate its ability to dewater a significantlylarger volume of the subsurface, and to provide a higher groundwater production ratethan extraction wells. During a 2-week pilot test, the DPE trench achieved a steady stategroundwater extraction rate of approximately 2.5 gallons per minute (gpm). Thispumping rate represents an average groundwater extraction rate 10 times greater than wasattainable with the previous multi-well groundwater extraction system. Includes tables, figures.

Product Details

Edition:

Vol. - No.

Published:

06/17/2005

Number of Pages:

8

File Size:

1 file , 830 KB