Pipes in Dutch bulb fields

It's quite a puzzle to get a water pipe into the ground between the flower bulb fields. The bulb fields may not be entered and salt water in the subsoil may absolutely not come to the surface. Nevertheless, the job was done according to plan. A credit to the entire team, including A.Hak’s own drilling specialists.

Those who have never seen the flower bulb fields with their own eyes may be familiar with the calendars that are sold at Schiphol. Not only a beautiful sight, the bulbs are also an important export product and as a country we do everything we can to protect them.

Harmful groundwater

The subsoil in this region contains salt water that can come to the surface when dug into certain soil layers. Building a new pipeline in such an area is therefore not easy. Nevertheless, the water company PWN wanted to adjust the water supply because the demand for drinking water in the Kop van Noord-Holland area has increased. The 400 mm diameter pipeline therefore had to be replaced by a 600 mm pipeline. A.Hak was commissioned to replace the pipeline over a total length of 5.9 km.

Drilling as a puzzle piece

PWN set two important conditions: the pipe had to be made of steel and the bulb fields were not allowed to be accessed at all. This was quite a puzzle for the team. ‘We started building last October, but we were already drawing in January’, says project leader Peter Hesselink.

From the years of experience of our own drilling specialists, it was immediately clear that horizontal drilling would form an important part of the puzzle's solution. ‘If no trenches can be dug, you go drilling’, says Peter. ‘This is logical for us, but it remains spectacular for the environment. That turned out to be the case again. The drilling under the village of Westwoud, at a maximum depth of 25 metres, was extensively covered in the newspapers.’

Stakeholder management

The fact that we have a lot of experience with directional drilling does not mean that it is simple. The integration in the route and the design of the individual drillings within the possibilities and limitations of the soil conditions are just a few examples of the different pieces of the puzzle. ‘The coordination with the stakeholders was also very important in this project’, says Peter. ‘It's one thing to come up with a plan, the practical execution is always different. Half a day's work can become a day if you suddenly come across a fence on the way that was not in the plans.’

Construction of a water pipeline in which groundwater management is crucial.