A F Howland Associates has experience in investigation of sites contaminated with hydrocarbon products, specifically NAPLs (Non-Aqueous Phase Liquids) primarily of heating oil composition.

Where contamination is suspected, exploratory holes are carried out to confirm of disprove its presence and standpipes are installed to allow in-situ sampling and monitoring of groundwater.  An oil/water interface probe is used to determine thicknesses of NAPL residing in the standpipe.  This equipment utilises a specially designed float to accurately measure the surface of the NAPL and a conductive probe to identify the surface of the groundwater.

Click here for an animation of an oil water interface probe in action


An environmentally diligent and considerate landowner was concerned about the potential for on-going and historical groundwater contamination beneath a recently purchased former fuel transfer depot.  AFHA were commissioned to carry out a site investigation and subsequently identified hydrocarbons in the subsoil.  Later monitoring, utilising an oil/water interface probe, found NAPLs to reside in standpipes.  Small scale removal by way of pumping to an on-site interceptor successfully removed significant amounts of NAPL which after further monitoring with the interface probe were proven not to return, suggesting that localised historical contamination around the standpipes was the cause of NAPL presence and that on-going contamination was not occurring.  Consequently, commercial redevelopment of the site was allowed to proceed without hindrance of regulatory enforcement providing a considerable commercial benefit to AFHA’s client.

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