Kessler pit

Kesslergrube at OpenStreetMap

Kesslergrube is the name of a large mixed landfill and contaminated site in the Grenzach district of the Grenzach-Wyhlen community in Baden-Württemberg , which was created and operated as several gravel pits between 1913 and 1969. From the 1950s until 1976, it was replenished with excavated earth, building rubble, household and commercial waste and more than 15,000 tons of toxic waste from the chemical and pharmaceutical industries, which pose an ecological threat to the environment.

The pits were backfilled by local industrial companies, garbage collectors and the community. Since the individual pits are close together, they are all grouped under the collective term Kessler pit.

The pit covers an area of approx. 52,000 square meters and has a deposit volume of approx. 310,000 cubic meters. Around three quarters of the area is undeveloped wasteland, a quarter is overbuilt with industrial buildings and a sewage treatment plant. The Kesslergrube is located directly on the banks of the Rhine in the western area of the company premises of BASF Grenzach GmbH (around 2/3 of the area) and an adjacent area of Roche Deutschland Holding GmbH (around 1/3 of the area) and is only a few hundred meters away from the town center. The pit has been examined and explored by engineering firms since 1991. The reports showed that the groundwater below the pit is polluted by toxic substances such as chlorobenzenes, aromatic amines and ammonium, which, however, do not penetrate into drinking water wells. There are no other hazards from the pit either. Some of the more recent expert reports are available online on the Lörrach district administration's website, older reports can be viewed on site.

In order to rule out long-term environmental hazards, the responsible district office of Lörrach determined in July 2011 that the mine was in need of renovation based on the assessment of the contaminated site assessment commission of the state of Baden-Württemberg. As a result, the two companies Roche and BASF had redevelopment concepts drawn up, which were approved subject to conditions by the Lörrach district office in spring 2014 and have been implemented since then. The renovation of Roche (Perimeter 1) should be completed by 2021. Proceedings are in progress against the encapsulation concept of the BASF section (Perimeter 2).

Restructuring circumstances

According to an administrative regulation of the state of Baden-Württemberg , the aim of a remediation measure should be to create a condition in which pollutant concentrations in the (formerly) contaminated environmental media can only be measured to the extent that they correspond to or come close to the natural or anthropogenic background values . The administrative regulation also states that in a large number of cases it does not make sense to pursue this goal, if it can only be achieved with an economically or legally disproportionate effort and / or because of the negative secondary consequences of the redevelopment an unfavorable environmental balance would arise. It is therefore necessary to weigh up all the circumstances of the respective individual case when setting remediation goals.

Drinking water pollution

There is currently no drinking water pollution from the Kesslergrube, since drinking water is usually a purified end product and the current drinking water wells are not in the immediate catchment area of the Kesslergrube. Several reports and publications confirm the complex and communicating hydrogeological conditions in the Basel agglomeration .