TYPOLOGY: ISCO with Direct Push
In an urban setting surrounded by residential buildings there was a need to decontaminate the soil of a location where plans for a large urbanisation project are underway. Preliminary investigations identified pollution associated chiefly with past manufacturing activities (de-greasing) in an old factory.
The contamination consisted primarily of chlorinated volatile organic compounds (CVOC); mainly tetrachloroethene (PCE) and its secondary degradation products, trichloroethene (TCE) and dichloroethene (DCE). High concentrations of contaminants were found during the studies in the soil’s less permeable layers.
ISCO con Direct Push
The technology chosen for the treatment was chemical oxidation with sodium permanganate (5 and 20%) injected by direct push.
The treatment area was roughly 1,500 m2, in which 37 injection wells were drilled to a depth of up to 10 m and nine existing wells were used to inject a total of 52,000 l of 20% NaMnO₄ and 36,000 l of 5% NaMnO₄.
Having an urban environment with numerous stakeholders where the soil (clayey-silt) has low permeability made this project somewhat unique, sensitive and complicated. Geostream, thanks to previous experience, has therefore come up with a plan of action that includes: injection equipment to act simultaneously at four points with specific control at each one; two fully waterproofed areas fenced off for temporary storage and preparation of the reagent; liquid-concrete equipment to seal the wells; areas for safety showers and equipment washing, and an area for storing contaminated materials.
Project data, preliminary estimates:
Injection ratio: 1,800 – 2,400 l/day, over the project’s duration (including installation/deinstallation of equipment): 40 – 55 days (8 – 11 weeks)
Final project execution data:
Injection ratio: 2,200 l/day, over the project’s duration (including installation/deinstallation of equipment): 50 days (10 weeks)