Dewatering & Water Treatment Solution for an International Airport

Project Location: Austin, TX

Owner: Confidential

Engineer: Walter P. Moore & Associates

GC: Hensel Phelps Construction Company

Project Revenue: $1,200,000.00

Project Start and End Date: February 2016- March 2016

Summary:

Griffin Successfully Lowered Groundwater to 35 feet below ground surface & Pioneers Successful Treatment of EPA’s Contaminants of Emerging Concern

The Challenge:

Construction of a new deicing facility at the airport required lowering groundwater more than ±35 feet (ft.) for an excavation approximately ±250 x ±200 ft.

During the start of the dewatering project, the groundwater was found to contain perfluorinated alkyl acids (PFAAs) which are among EPA’s list of emerging contaminants. The PFAAs family of chemicals is made up of various long and short chain compounds, that are often difficult to treat. A sophisticated water treatment system was needed to discharge any water from the site.

The Solution:

To obtain the required drawdown, twenty (20) deep wells were installed approximately to 50 ft. surrounding the Soil Nail and Shotcrete shoring system. 1-2 horsepower (HP) submersible pumps were installed in each well. The entire system pumped approximately 500 gallons per minute (GPM) and provided water level drawdown to more than 35 ft. below ground surface for the duration of the project.

To treat the water for discharge, Griffin applied an innovative mix of filtration media to treat for both long and short chain PFAAs. The system continuously handled the 500 GPM flow from the dewatering wells. The treated water was comprehensively tested and the PFAAs were reduced to non-detectable levels at the end of the treatment train.

The Griffin Difference:

The deep excavation dewatering system was successfully completed in just over one (1) month andstayed in operation for the duration of the 9-month project. Due to the unexpected contamination, Griffin’s ability to quickly modify the scope of the project and provide water treatment was essential in keeping to the construction schedule. To ensure early detection of any media breakthrough, and to prevent any out of compliance discharges, Griffin incorporated the use of lead-lag series configuration in our treatment methodology.