The frequency of severe rainfall is increasing. During severe downpours, the sewer system in the village of Amerongen is not always capable of coping with such large volumes of water. A limited rainwater drainage capacity, coupled with extreme precipitation, may cause streets, gardens, or basements to become waterlogged. The Amerongen Rainwater-proof project is aimed at minimising the future risk of waterlogging.
The project covers five sections, four of which are located on the east side of the village. The fifth section involves the old village. In some streets, the municipal authorities are replacing the highly outdated sewer systems. Within the Amerongen East area and the old village, facilities are being constructed to disconnect downspouts from the sewer system. This will reduce the burden on the sewer system, while allowing clean rainwater to directly infiltrate into the soil. This benefits both the sewer system, and nature.
At several locations in Amerongen East, infiltration pipes and wadis are being constructed to disconnect (clean) rainwater downspouts from the combined sewage system. Rainwater is thus collected and retained for a longer period of time. The pipes and wadis will release the water into the soil, thus preventing it from disappearing into the sewer. In addition, the highly outdated sewer systems at several locations in Amerongen are being replaced by new sewers.
The construction of the above facilities will immediately reduce the current combined sewage system overflow onto the floodplains. In the future, such overflow will only operate during extreme precipitation and will consist of rainwater only.
In the northern part of the village (along De Del in Amerongen), in the vicinity of the cemetery, the creation of a small waterfall will expose rainwater from the subsoil system. From this point onward, rainwater will flow into the newly constructed wadi. The wadi’s drop totals some three metres. Once the wadi fills up, a subsoil transport sewer will transfer the water flow towards the floodplains. Small benches will be placed by the wadi and the waterfall for an optimum overview of the water system. An information sign next to the benches will explain how the surface and subsoil water systems work. Elsewhere in the project area, a water storage reservoir will be created. During dry summer months, this water supply can be pumped up to water trees and shrubs.
The above solutions have been realised in collaboration with the municipality of Utrechtse Heuvelrug and BOOT engineers. Several meetings have been organised in Amerongen in order to involve the local residents in the process. During these meetings, the residents could actively weigh in on the climate-proofing process. At the first meetings, the provisional development plans were presented. Residents gave their views on the adaptations to the greenery that are necessitated by the construction of infiltration pipes and wadis. It goes without saying that the process raised a great many questions. What exactly is going to happen in my street? And how will this affect me? Alderman Gerrit Boonzaaijer, Kees van Zutphen (municipal project leader), and BOOT engineers William Hendriks, Bertrick van den Dikkenberg, and Maarten Baan answered these questions in concrete and univocal terms. During the last residents’ meeting, the final plans were presented.
The municipality of Utrechtse Heuvelrug is now going to elaborate the development plans. Work on the first section is scheduled to commence in early 2019. The other sections will be tackled successively.
William Hendriks (projectleider)