Improved devices, systems and methods for measuring in situ saturations of non-aqueous phase liquids and/or petroleum in media such as soil. A clear or otherwise UV-transparent well for detecting fluorescence in a soil column having a transparent casing and an oil sensing device positioned in the well configured to monitor the soil column. A method for real-time estimation of LNAPL saturations in media, including emplacing a UV-transparent well in the media and recording fluorescence in the media via an oil sensing device.