Technical Construction Supervision Hydrogeology
Gruner AG's environment division planned the construction project "Securing of the Steinenweg Railway Crossing and Removal of the Wella/Schützenhaus Railway Crossings" in Hölstein BL and provided site supervision. The groundwater protection zone Helgenweid/Tiefenmatt, from which the drinking water for the municipality of Hölstein and the city of Liestal is sourced, was located in the immediate vicinity of the construction site. Considering these challenging conditions, the client arranged for the construction and the completion of the access road to be fully supervised by a hydrogeologist as well as a soil specialist to ensure correct soil handling. Both areas of expertise were covered by Gruner AG’s Environment Division.
As a basis for the groundwater protection, a groundwater-monitoring plan as well as an incident action plan were prepared in advance. To ensure that the construction work did not jeopardize the groundwater capture, the construction site was regularly inspected by the two expert site supervisors. Once a month as well as before the start and after the completion of the construction work, the groundwater within the project perimeter was sampled at two monitoring sites. Since the groundwater was only 3 to 5 m deep, a newly acquired 12 V submersible pump that could be connected to the power supply of the company vehicle was used for the sampling. This allowed for the omission of a heavy diesel generator when collecting the samples in the field.
The supervision was provided over a total of 11 months. No groundwater issues that were attributable to the construction site were found. The preservation of clean drinking water was ensured at all times.