Sustainable sanitation provision is challenging developing countries, especially sub-Saharan countries. Among those low-income sub-Saharan countries, Ethiopian towns and cities struggles with poor sanitation problems. The main objective of this research was to assess and select appropriate sanitation options for urban context of the town of Kombolcha, based on a comprehensive analysis of technical, environmental, social, economic, and institutional criteria. A multi-criteria decision analysis was used to assess and rank technology options to determine the most suitable solution for Kombolcha City. To gather information on the state of urban sanitation, a variety of methods has been employed, such as surveys, interviews, focus groups, observations, and document analysis. In this study, 243 households were approached which was a 97.94% response rate. Based on the result of our survey there were mostly five types of household toilets technologies in Kombolcha Town. These technologies included simple pit latrine with a slab which is 38.6%, cistern flush toilet (1.5%), pour/manual flush toilet (6.5%), VIP latrine (33.2%), and pit latrine without slab (20.2%). Similar ketenas or Kebeles (the smallest administrative unit within a town or city, typically functioning as a local government or community division) form were merged into groups. Consequently, 4 clusters of Kebeles were identified for the study with similar characteristics for sanitation technology option adaptation or intervention. The final weights of the selected criteria during pairwise comparison were environmental (37.3%), health (38.7%), technical (11.6%), economic (8.1%) and socio-culture (4.3%). Based on those main criteria the selected possible technology option for cluster 1 was “Pour Flush toilet connected to Twin Pits”, for cluster 2 “Pour flush toilet + sink and shower + watertight septic tank”, for cluster 3 “Flush toilet + sink and shower + simplified sewerage system” and for cluster 4 “Flush toilet + sink and shower + septic tank + solid free sewer system”. Moving forward, we recommend implementing pilot projects to test the selected sanitation technologies in the identified clusters. This will help evaluate their feasibility and effectiveness in improving urban sanitation. Collaboration with local government, sanitation experts, and community stakeholders will be crucial for successful implementation.

Stability analysis on underground excavation is crucially helps to reduce collapse risks and optimize resource extractions. In this study numerical method was employed for stability analysis on the selected opal mine drift. Intensive field investigation of rock mass characterization, geometry of current mine drift, discontinuity measurements, and insitu rock mass characterizations were done. The Delanta mining site opalized rock layer is naturally weak and unwelded to moderately welded, which is not easy for bolting and steel reinforcements. The Delanta opal resource is found in the deep cliffy gorge greater than 200 m depth from surface. To obtain compressive strength of intact rock properties, laboratory tests of rock samples were conducted. The insitu parameters and laboratory tested parameters were utilized for numerical stability analysis. The study shows stress conditions, deformation behavior and determine pillar dimensions based on the selected rock mass behavior which has critical importance on the safe mining operations. Stress–strain simulations were conducted on 1-m, 2-m and 3-m cross-section of natural rock pillar with 2 m height and 1.5 m width of mine excavation. The evaluated mine drifts have high deformability at the mine gate and less deformable inside the mine drift. Compressive strength of rock samples was low, and the generated deformation behavior of rock pillars is less while excavation move inside 100 m at MinchWuha mining drift. Based on the existing rock mass properties, the mine drift pillars are unstable in 1-m, and 2-m rock pillar dimensions. The mine excavation was more stable while the natural rock pilar dimensions increased to 3-m. The Delanta district mining system should design in room and pillar methods to reduce the risk vulnerability of miners and to increase the opal resource extraction efficiently. Natural rock support system would be better by creating rock pillar than man-made supports. Thus, mining system in the Delanta mine sites should be customized by implementing room and pillar mine systems, which increases the mining safety and resource extraction optimizations with sustainable mining.