Successful hydraulic-biological in-situ remediation on a former air base

On the site of a former airbase in the Rhine-Main area, contamination of the soil and groundwater/seepage water was detected during exploratory investigations in the area of a former aviation petrol tank and in the outflow of an oil separator. The contamination of the subsoil consisted of aromatic hydrocarbons (BTEX), mineral oil hydrocarbons (MKW), polycyclic aromatic hydrocarbons (PAH) and volatile halogenated hydrocarbons (LHKW).

MuP Umwelttechnik Heidelberg (until 2019 still IBL Umwelt- und Biotechnik) then carried out a detailed investigation on the 24,500 m² site. A subsoil profile was created with around 80 percussion core soundings and groundwater measuring points.

Silt is present on the surface, which is partially overlaid by fillings. A layer of sand and gravel of varying degrees follows on top of the silt, which in turn is underlain by a tertiary clay layer with a channel structure. The groundwater or stratum water circulates in this channel structure, transporting the pollutants.

With this information, MuP Umwelttechnik planned, built and operated a remediation system for soil and groundwater purification. Due to the local conditions, the decision was made in favour of hydraulic-biological in-situ remediation with horizontal infiltration and extraction pipes as well as vertical wells. Four remediation wells and seven parallel extraction lines were connected to the plant and a total of around 1.5 km of pipework and 2.3 km of supply and communication lines were laid underground across the entire site. The refurbishment took a total of 17 years. From 2004 until the refurbishment target values were reached in 2021.

MuP Umwelttechnik was actively involved in the remediation from the beginning until the dismantling of the plant in February 2023 and has developed a groundwater monitoring concept for aftercare in order to be able to conclusively assess the success of the remediation.