Engineering services, including construction supervision (SIA 41–53), for the development of Seewenweg, 4146 Hochwald SO

Initial Situation

For the most part, Seewenweg has a width of between 3.5 and 4.5 meters and is in poor condition. There are only sporadic edge restraints, and the drainage system is inadequate. Existing lighting is outdated. Assessments indicate that the current road’s foundation lacks sufficient load-bearing capacity and is not frost-resistant.

According to the development plan dated November 28, 1997, Seewenweg is classified as a collector road. The plan specifies a road width of 5.0 meters, and the land has already been designated as a dedicated road parcel in the land register.

Due to the poor structural condition, insufficient cross-sectional width, and the need to realign the road in certain sections, a complete replacement and expansion of Seewenweg are required.

Road Construction

In accordance with the development plan, the new road—spanning approximately 910 meters—will be constructed with a constant width of 5.00 meters between Baselweg and Nettenbergweg. In the two sections between Rüteliweg and Höfliweg (north) and between Höfliweg (south) and Nettenbergweg, the existing road lies partially outside the designated road parcel; consequently, the expansion in these areas effectively amounts to a realignment.

The project includes a new foundation layer and pavement, as well as continuous edge restraints, a drainage system, and new lighting.

Water Main – Seewenweg

The water mains in the sections between Bürenweg and parcel 3574, as well as between Nettenbergweg and Passwangstrasse, must be replaced or supplemented. The new water mains will consist of PE (polyethylene) plastic pipes with a nominal diameter (NW) of 125/102.2 mm. ...with a nominal diameter (DN) of 160/130.8 mm. Existing hydrants will be replaced, and a new hydrant will be installed near the junction with Passwangstrasse.

All service connections to individual properties will be connected to the new main and replaced within the road area (extending up to 1 meter beyond the property boundary).

Rüteliweg Water Main

To ensure the water main in Rüteliweg functions as a looped system, the existing line must be extended and connected to the water main in Seewenweg.

Nettenbergweg Water Main

In the section between Nettenbergweg and Radackerweg, the existing water main runs outside the public road area, crossing private property. This line will be decommissioned and relocated to Seewenweg. A new water main will be installed along Nettenbergweg to provide service to the properties. This new main will consist of PE (polyethylene) pipes with a nominal diameter (DN) of 125/102.2 mm. Two new hydrants will also be installed.

All service connections to individual properties will be connected to the new main.

Water Main – Plot 2700

To ensure adequate water pressure for the properties located on plots 2698, 2699, 2700, and 2702, a new water main is planned for the private road branching off from Seewenweg. All service connections will be connected to this new main and replaced within the road area.

Seewenweg Sewer Lines

To ensure the required flow capacity, the two sewer sections between manholes KS 101 and KS 103 must be replaced with larger-diameter PE pipes (DN 400 mm).

The remaining sewer sections will be rehabilitated using an inliner (trenchless lining) method. Stockenweg Sewer Pipeline

The planned sewer diversion via Stockenweg will allow for the decommissioning of existing sewage pumping stations, thereby preventing the undesirable discharge of combined sewage into the groundwater protection zone.

Since a large portion of this pipeline route passes through the "Sm" groundwater protection zone, the necessary measures have been established in coordination with the Office for the Environment of the Canton of Solothurn. To ensure watertight integrity, the pipeline (pipes and manholes) within the "Sm" groundwater protection zone must be constructed using plastic (welded PE). The number of inspection manholes is to be kept to a minimum.

The pipeline will be constructed using PE pipes with a nominal diameter (DN) of 400 mm. To facilitate future maintenance as well as the required CCTV inspections and leak testing, individual pipeline sections will have a maximum length of 125 meters. The depth of the pipeline will be kept constant throughout at 1.40 meters. This approach allows for the use of milling techniques during construction while minimizing the need for rock excavation.