CONTAMINATED SEDIMENT REMOVAL
HURON RIVER – MGP SITE CLEAN UP
ANN ARBOR, MI
Great Lakes E&I performed the excavation of impacted soil at a former MGP site along the Huron River in downtown Ann Arbor, Michigan. Primary tasks involved clearing and grubbing of the site, dewatering, installing a trapping cap, and disposing of all impacted material from the site. Parties involved with this project included a major utility company, a local engineering firm, the City of Ann Arbor, and the Michigan DEQ. Given the close proximity of the site to the downtown area, crews had to manage odor control on a daily basis utilizing a Piian misting system. Prior to loaded trucks leaving the site with contaminated material, loads were sprayed with a foaming odor suppressant.
The removal and disposal of upland and river bank soil was required due to the potential source of pocket area concentrations of contaminants. These contaminants represented a potential future source of pollution to the Huron River. The area of sediment to be removed was from a 15 feet wide by 1,000 feet long section along the river.
The excavation phase of the project involved two excavators removing contaminated material in three, 400 feet sections. During excavation from the river, a 400 foot turbidity curtain was used along with a 50 foot carbon filter, sorbent oil boom to capture any contaminated material from flowing downstream. As the excavation progressed along the river, the booms were re-positioned three times throughout the project. Approximately twenty-five loads per day were transported daily and a total of 50,000 cy of coal-tar contaminated material were removed.
Once the excavation phase was concluded, the site was backfilled and capped. A NAPL (Non-Aqueous Phase Liquids) trapping cap and collection system were installed. Site restoration concluded with a six inch layer of top soil, seeding, and the placement of erosion protection shrubs and trees.