Ground Water and Low Permeability Soil Remediation: Huntsville, Alabama
Leggette, Brashears & Graham, Inc. (LBG) excels at working closely with our clients to meet both required environmental and business objectives associated with site remediation. LBG designed a combination multi-phase extraction (MPE) and soil-vapor extraction (SVE) system to remediate trichloroethane and dichloroethene impacted soil and groundwater beneath an operating electronics assembly facility. This system replaced an ineffective pump and treat system installed by others. Net client savings are estimated at $5 million.
Keeping an outdoor storage area used by the electronics facility accessible during installation and operation of the system.
Determining the location of more permeable soil layers in a complex inter-layered low permeability environment. Pilot test data indicated low pneumatic permeabilites of the soil ranging from 10-7 to 10-9 cm2.
The radius of influence of groundwater extraction measured during pilot testing was limited to 15 feet.
SCOPE OF WORK
LBG engineers and geologists, working with the client, developed an innovative design to remediate impacted soil and groundwater while minimizing the impact to facility operations.
These design tasks included:
Performing an electrical conductivity (EC) investigation to determine the location of more permeable soil layers.
Designing the MPE/SVE extraction points as 29 nested pairs with the screened intervals matched to the location of the more permeable soil zones as determined by the EC investigation.
Minimizing the impact of installation on the operation of the facility by plumbing the nested wells together at three separate locations. This design resulted in savings in piping costs and minimized disruption to plant operations.
With the new system in place, annual VOC removal rates increased approximately 250 percent.
The MPE/SVE system has reached asymptotic recovery levels and system shutdown and long-term monitoring is being pursued.