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The retention of rainwater runoff through green roofs provides a number of positive effects in achieving resilient urban infrastructure. The most significant benefits include adaptation to climate changes, such as alternating between intense rainfall and droughts, as well as reduced capital and operational expenditures for sewer systems. The primary objective of this research is to analyze the mitigation effect on the run-off from an extensive green roof in the Sofia (Bulgaria) area for the first time. To accompli...

At present moment, Bulgarian regulatory documents lack rainfall hyetographs that can be used in computer models of sewer networks. In the conditions of climate change and the occurrence of extreme precipitation phenomena, this leads to difficulties in the application of sewer network modeling in solving engineering problems. It is not possible to perform a normatively defined determination of hydraulically overloaded sections of the sewer network, as well as to determine the expected frequency of flooding and floo...

Passive acid mine drainage (AMD) treatment technologies are technically simplified systems that allow easy control, low capital and operational expenditures, and operating regime that is resilient to varying conditions. Classical technologies for the treatment of AMD with high metal content are based on the process of chemical neutralization. The most commonly used materials or reagents to induce passive neutralization are lime (slaked or quicklime), limestone, soda ash, magnesium hydroxide as well as industrial w...

The design of urban drainage systems in the European Union generally follows the requirements of the EN 752 standard. Nevertheless, it uses a classical approach that aims only to convey stormwater runoff away from the settlement boundaries, thus preventing local problems. On the other hand, global tendencies are oriented towards a more sustainable approach for climate-adaptive metropolitan infrastructure. To address problems like urban expansion, expected future heavy rainfall events, sewer overloading, flooding, ...

Acid mine drainage (AMD) is a significant environmental issue especially in countries like Bulgaria that currently has 486 closed and abandoned mining waste facilities including tailings, dumps and heaps. Some of them are thoroughly investigated and known for their low pH levels and high metal and metalloid concentrations. The most conventional active treatment method for AMD involves neutralization through the use of different reagents. However, a significant limitation in the application of this method is the la...