Air Sparging at Fort Greely, Alaska

Presented by

Aung Syn & James Powell

Location

• The Texas Tower Site, U.S. Army’s Fort Greely military facility.

• Population 461 residents.

Background

• The Texas Tower Site consists of four buildings.

• While demolition of one of the buildings in 1990, a release of petroleum hydrocarbons was discovered.

• Originated from an underground fuel line which supplied heating oil to the demolished building from an aboveground storage tank.

Contaminant

• Soils consisted mainly of sand, gravel, cobble, and silt.

• Approximately 6,300 cubic yards of contaminated soil.

• Spread: vertically 50 feet deep and horizontally off an area of 5,655 square feet.

• Groundwater was encountered between 23 and 50 ft below ground surface.

Contaminant

• Diesel fuel (No. 2 fuel oil) consists of unbranched paraffin.

• Flammability: High

• Toxicity: High

• Two of the three monitoring wells where contaminated.

Technology Used• Method i) Air Sparging System

• Two air sparging wells drilled of depth 55 ft with 2-inch-diameter.

• Provided 23-60 cfm of air to the saturated zone.

• Operated for 18months.

• Method ii) Soil Vapour Extraction System

• Three SVE wells were drilled to 52 feet with 4-inch-diameter.

• Soil vapour was removed from the wells at a rate of 600 cfm.

• Operated for 18months.

• On 15 August, 1995, 4,000 gallons of nutrient solution was injected into the SVE Wells.

• Nutrient solution was a mixture of 50 lbs of fertilizer to 1,000 gallons of water.

• Use of micro organisms to degrade contaminants to obtaining harmless chemicals as end products.

• Method iii) In Situ Bioremediation

Timeline

Result

Conclusion• Treatment in soil and groundwater met the remedial

goals.

• Highly contaminated soil had been excavated and treated off site.

• The leaking fuel lines that had been the source of the release had been removed.

• No compounds for which maximum contaminant levels have been detected at the site for more than two years of monitoring after completion of cleanup.

• Total Cost of Cleanup: $295,760