DISASTER PREPAREDNESS: A case of Masinga Flooding Presented by: Charles Ogugo 2017 4th COPI-EH FORUM, KSSC MATENDENI 16thMarch, 2017

Presentation Outline Introduction & Background Flooding: Causes and Effect Flooding: Improvement works/remedial actions Recommendation & Conclusion

Introduction & Background Masinga power station has two (2) Kaplan hydro turbine generators rated at 20Mw each. The station was commissioned in 1981 On 10th April 2013, the station was flooded as a result of entry of storm rain water into the power house, Generator area and Turbine floor The flooding was culmination of unprecedented torrential rains that lasted a approximately two-hours Entry of storm water into the power house was through holes drilled through the concrete wall for cable entry Turbine floor area was flooded with storm water getting through cable entry points on the generator floor

Introduction & Background Cont.-Photos Storm water run off upstream of the last culvert to Masinga Power Station Storm water run off upstream of the last culvert to Masinga Power Station

Introduction & Background Cont.-Photos Signs of erosion after heavy rains. Upstream of the last culvert to Masinga Power Station Directional indication of surface run off flow. Towards Masinga Power Station main gate

Flooding: Causes Blocked drainage channels along Kaewa-Masinga road. Runoff was not adequately directed through the culverts across the road. Blocked culverts by contractor who laid parallel KITWASCO water line Depressed drainage capacity of the drainage system around the power station area Blocked storm drains around the power station area

Flooding: Causes, photos Blocked drainage culverts along Masinga-Kaewa road Blocked drainage culverts along Masinga-Kaewa road

Flooding: Causes, photos Cont… Blocked drainage culverts along Masinga-Kaewa road. Note the new parallel water line laid by the contractor Blocked drainage culverts along Masinga-Kaewa road

Flooding: Causes, photos Cont… Blocked drainage culverts along Masinga-Kaewa road. Note deposits of eroded soil

Flooding: Effect………… Unit 1: Loss of generation: The unit was out for 74.96 hours Generator and electrical auxiliaries were affected: Cleaning, drying and other restoration works done. Tested and commissioned. Replacement of turbine bearing oil due to water ingress Staff costs incurred

Flooding: Effect Cont…… Unit 1: Stator IR Values at 2.5 kV after inspection and cleaning 15 sec 60 sec 3 min 10 min PI R-YBE 595 MΩ 2.12 GΩ Y-RBE 610 MΩ 2.26 GΩ B-YRE 605 MΩ 2.20 GΩ RYB-E 232 MΩ 820 MΩ 1.94 GΩ 3.98 GΩ 4.85 Stator temp was 30.3 degrees C

Flooding: Effect Cont…… Unit 2: Water ingress in unit 2 was higher than in unit 1 Loss of Generation: The unit was out for 317.42 hours Generator initial IR Value was 0 ohms after flooding Generator was thoroughly cleaned with special quick drying white spirit and dried with hot air blowers. IR Value measured after above restoration activities was unsatisfactory. The unit was rolled at speed no load condition to aid in further evacuation of any moisture

Flooding: Effect Cont…… Unit 2: Some damage occurred on the stator wedge stoppers at the windings overhang (Insulation had peeled off). This was noticed after the spinning operation Water ingress occurred in combined and turbine bearing oil. The oil was replaced Staff costs incurred

Flooding: Effect Cont…… Stator IR Values at 2.5 kV after inspection and cleaning with quick drying white spirit cleaning 15 sec 60 sec 3 min 10 min PI RYB-E 208 MΩ 640 MΩ 1.49 GΩ Stator temp was 25 degrees C Stator Final IR Values at 2.5 kV after unit spinning to further evacuate moisture and repair work 15 sec 60 sec 3 min 10 min PI R-YBE 628 MΩ 2.14 GΩ Y-RBE 614 MΩ 2.01 GΩ B-YRE 1.87 GΩ RYB-E 256 MΩ 737 MΩ 1.61 GΩ 3.88 GΩ 5.30 Stator temp was 26 degrees C

Flooding: Drainage System improvement JOH-KGN001-20071212-JvW-X1 Flooding: Drainage System improvement Opening up blocked culverts along Kaewa-Masinga road. This was meant to direct flow to the other side of the road. Re directing surface runoff away from the power station area. Construction of new drainage system Upgrading existing drainage system to accommodate increased flow Strengthening the walls of the open drainage channels. Blocking cable entry points through which storm water accessed the power house

Flooding: Drainage System improvement Storm water flow into the last drainage culvert before Power Station main gate Storm water flow exit the last drainage culvert before Power Station main gate

Flooding: Drainage System improvement Re directed flow of surface run off in the open chanel after initial construction stages. Surface run off exit culvert and flows through open chanel after initial construction stages.

Flooding: Drainage System improvement Re directed flow of surface run off along Masinga Kaewa road after the junction to the power station. New culvert constructed along Masinga-Kaewa road to direct flow across the road. Culver constructed using old penstock pipes from Tana.

Flooding: Drainage System improvement, reinforcement. Due to continued heavy rains and resultant runoff experienced, new open drainage channels could not contain increased flow volume hence damaging the walls. Gabion boxes (Rheno gabions) were used to reinforce culvert wings and back walls of open channels.

Flooding: Drainage System improvement, reinforcement-Photos Damaged walls of the new open channel before reinforcement with Gabion boxes. Start of reinforcement works

Flooding: Drainage System improvement, reinforcement-Photos Cont… Allowance for gradual overflow Reinforced walls of the open channel. Reinforced walls of the open channel. Note: Allowance for gradual over flow incase of increased volume of surface run off

Recommendation & Conclusion Drainage system around the power station still require further improvement works Existing old open drainage channels will have to be expanded, stone pitched and reinforced There was remarked improvement in the flow of storm water runoff along Kaewa-Masinga road Much of the runoff is currently diverted across the road before getting to the power station area Other stations can learn from Masinga experience

THANK YOU