The end of 2020 in fact has proven to be a brave start of a new innovative cooperation between Sofiyska Voda AD and The centre of competence “CLEAN and CIRCLE”.

Our company supported the scientific team of “CLEAN and CIRCLE”, involving specialists from the University of Architecture, Civil Engineering and Geodesy (UACEG) and Sofia University St. Kliment Ohridski, in a project for studying the dynamic relationship between rain and water runoff in the sewer system. For this purpose, we found the most suitable building of the company with a flat roof, which drains the stormwater separately from the domestic wastewater. The building of the pumping station for sludge recirculation on the territory of Kubratovo WWTP turned out to be perfect for that. First, the project includes the preparation of the building itself, then installation of measuring devices and a rain gauge station. Meanwhile, a team from UACEG won a project at the CENTER FOR RESEARCH AND DESIGN at UACEG to plant a part of the roof and to monitor the effect of landscaping and the quality of rainwater.

Only in the autumn of 2021 the “green” roof was completed and the project moved to the monitoring and analysis stage.

What are we doing?

In the preparation, the roof was divided into two halves, as one remained with the standard bituminous coating, while the other was prepared for landscaping. A separator was placed between the two halves, so that the rainwater did not run from one side to the other. Under the two rain gutters of the building, a team of UACEG installed flow meters, which already started reading the runoff from the roof. In parallel, our team mounted one of the rain gauge stations on the roof to measure rainwater quantities. Thus, we strive to achieve maximum accuracy of the results in aligning the measurements of the fallen rain on the roof and the rainwater runoff through the gutter.

The “green” moment

The mounting of the Green Roof took place in the fall of 2021 to coincide with the raining season and for the vegetation to sprout. Back in the first visit of the colleagues from UACEG on a moist and foggy day, the specialists noticed that the gutter from the “bare” roof was dripping, while that from the side with planted vegetation had remained dry. 

What’s next?

We are waiting for the spring and the new active raining period this year. The research continues with an analysis of the obtained data, measurement of the quality parameters of rainwater, and all of us are looking forward to seeing the mosses turn green.

*The work is carried out jointly with the Faculty/Department of UACEG through the project BG05M2OP001-1.002-0019: “Clean technologies for Sustainable Environment – Water, Waste, Energy for Circular Economy”, financed under the Operational Program "Science and Education for Smart Growth”, co-funded by the European Union through the European Structural and Investment Funds, as well as through the Research, Consultancy and Design Center at UACEG.