”Maveplan succeeded in every area of the project. I would definitely recommend working with them in the future.”Taru-Maaria Herttua-Suokko
City surveyor
City of Seinäjoki

More frequent heavy rains have increased the risk of urban flooding everywhere in Finland. When an extensive arterial drainage project needed to be carried out in the fields around the headwaters of the River Pajuluoma, the project team wanted to seize the opportunity to assess the adequacy of the coefficient of transmissibility of the lower course of the River Pajuluoma, which runs through the centre of Seinäjoki, in the event of a flood.

Due to the complexity and importance of the project, the project team paid extra attention to selecting the right project partner. According to city surveyor Taru-Maaria Herttua-Suokko, there are only a handful of reliable companies in the field with enough references to meet the selection criteria.

A phone call with Maveplan was enough to give the project team a clear idea of what methods and resources would be needed to carry out the project successfully. Maveplan prepared a written quotation covering the entire project, and work was ready to start after the quotation had been accepted.

The arterial drainage of the land around the headwaters went according to plan. To assess the adequacy of the coefficient of transmissibility of the lower course of the river, the project team relied heavily on Maveplan’s expertise in the modelling of the water systems. Due to the meandering nature of the stream bed, it has several recreation areas, including ponds, and up to 32 bridges or culverts with up to 30 metres of vertical difference, making the stream bed particularly challenging to model and survey. However, with modern technology, Maveplan’s experts succeeded in modelling and surveying the stream bed.

The surveying data of the stream bed network, locations of bridges and culverts and the lowest structures exposed to water were analysed using the MicroStation software. The data were used as the basis for creating and analysing a HEC-RAS water flow model using different flow rates for the lower course of the River Pajuluoma.

After analysing the results, the project team found that the flood levels would not cause significant harm to residential buildings, meaning that there was no need to start clearing vegetation and rocks away from the river or straightening the river. This helped save a significant amount of money when the unnecessary excavation work, which could have compromised the park-like vistas around the river, could be avoided.

Taru-Maaria Herttua-Suokko says that overall, Maveplan did a great job with the project and that Maveplan can also help others who might need similar services.