Detailed geotechnical investigation and engineering design for landslide mitigation under Phuentsholing Thromde and flood protection including hydrological modeling for Pasakha industrial area.
The project implementation unit (PIU), NAPA II project under Phuentsholing Thromde intended to hire the services of a competent consultancy firm through UNDP to carryout detailed geotechnical investigation of the four identified landslide areas in Rinchending and to west of Reldri School as well as the study for Barsa and Singye river watershed area with focus on flood hazard mitigation measure for landslides and flood along with detailed engineering design. For the purpose, international firm ISMRN in association with APECS consultant was selected as the most competent consultancy for this purpose who successfully accomplished the task. The mitigation measures were implemented following the approval of the modelling and structural design.
Following were the major scope of the assignment:
- Carryout detailed topographical survey and cross section survey for flood modelling.
- Carryout jointly the detailed geophysical survey to ascertained the subsurface geological stratum on landslide areas.
- Conducted rotatory drilling test for the entire area.
- Carryout field investigations-SPT/PPT, Pit excavation and sample collection for laboratory testing’s.
- Determine jointly the requirements for engineering structures such as retaining walls and complementary bioengineering applications
- Prepare of mitigation plan and detail mitigation measures needed to be adopted along with the cost estimates and timing for corrective measures and actions
- Preparation of BoQ and engineers’ cost estimate and technical specification for implementation of mitigation structures.
Geotechnical study of Takse (Trongsa), Buli(Zhemgang) and Gomtu(Samtse) proposed townships.
The assignment on geotechnical study involved thorough data collection encompassing geology, topography, hydrology, land use and geotechnical aspects that impose risk to developmental activity and environment. The study also included risk mitigation action plan to minimize the adverse effects of above factors to developmental activity and environment. The findings and recommendations of the geotechnical assessment was incorporated in the preparation of Development Plans.
Following were the major scope of the assignment:
- Carry out field surveys to confirm desk study interpretation and gathered supplementary data
- Identify, assessed and prepared instability inventory maps (landslides, erosion, debris flow, scouring, toe erosion, creep, subsidence, land degradation, rock fall, planner failure, wedge failure, toppling etc..) within the study area, and mapped the different level of hazards posed by different sources.
- Identify and assessed slope of the study area indicating the slope classification and level of hazards posed by topography including slope stability analysis of soil and rock slopes
- Identify and assessed the strength of geological materials by conducting necessary field and laboratory test and analysis.
- Carryout field investigations-SPT/PPT, Pit excavation and sample collection for laboratory testing’s.
- Identify, assessed and prepared geomorphologic maps for the instabilities
- To prepare of geological, geomorphological, geotechnical slope, multi-hazard and mitigation structure maps.
- Assist the risks to existing infrastructures
- Inspect high risk locations to define potentials solutions
- To determine requirements for engineering structures such as retaining walls and complementary bioengineering applications
- Preparation of mitigation plan and detail mitigation measures needed to be adopted along with the cost estimates and timing for corrective measures and actions
- Preparation of BoQ for proposed mitigation structures
- Description and technical specifications for each suggested mitigation measures including detailed cost estimates.