Operation and Maintenance Manual for Malankara Dam
(KL07HH0049) Water Resources Department Government of Kerala
O&M Manual of Malankara Dam August 2020
Operation and Maintenance Manual for Malankara Dam
(Prepared By) KERALA WATER RESOURCES DEPARTMENT STATE OF KERALA August 2020
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O&M Manual of Malankara Dam August 2020
Government of Kerala Operation and Maintenance Manual Malankara Dam
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O&M Manual of Malankara Dam August 2020
KERALA WATER RESOURCES DEPARTMENT
Disclaimer
This Operation and Maintenance Manual for Malankara Dam in no way restricts the dam operators in digressing from her/his responsibilities. The Dam Operators must exercise appropriate discretion and good judgment based on actual site condition when implementing and using the operation and maintenance manual for managing the workings of the dams and appurtenant structures.
The manual was developed for the purpose of organising and managing the operation, inspection and maintenance of the dams for reducing risk and optimizing performance of the dams as a general guide.
For any information, please contact:
THE CHIEF ENGINEER PROJECT II KERALA STATE WATER RESOURCE DEPARTMENT THIRUVANANTHAPURAM, KERALA Email: [email protected]
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O&M Manual of Malankara Dam August 2020
FOREWARD
Globally, the Operation and Maintenance (O&M) Manual of a dam/barrage is one of the most important documents which is supposed to be put in practice right from the initial filling of reservoirs. In order to address the operation and maintenance aspects, ongoing Dam Rehabilitation and Improvement Project (DRIP) has requisite scope to prepare new or update existing O&M manuals for all DRIP dams, which will become very helpful to Dam/Barrage Owners in addressing the dam specific issues comprehensively in future.
This Operation and Maintenance (O & M) Manual developed is a detailed set of written descriptions with step-by-step procedures for ensuring that the dam is safely operated, frequently inspected and properly maintained. Timely inspection and preventative maintenance is necessary for the safe functioning of the dam and continued productive use of the dam and reservoir.
The format of this manual is prepared following the principles published in 2018 CWC Guidelines for Operation and Maintenance of dams for the use by all Dam/Barrage Owners in developing their own site-specific manuals. Each section of the document provides the necessary instructions to operate inspect and maintain their dams.
It is recommended that all dam officials in charge to use this manual for ensuring that the dam is operated and maintained in a sustainable manner and will continue to derive benefits.
Chief Engineer
Projects – II
Thiruvananthapuram
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O&M Manual of Malankara Dam August 2020
PREFACE
Malankara Dam and Reservoir are owned and operated by Irrigation Department, Kerala. The Malankara dam is an earth cum masonry dam across Thodupuzha river, a tributary of Muvattupuzha river. It is located at Muttom in Idukki district near Thodupuzha- Moolamattom road and was constructed for the Muvattupuzha Valley Irrigation Project (MVIP). The dam site is about 27 Km from Muvattupuzha town and 8 Km from Thodupuzha town. There is a network of canal system consisting of two main canals on either banks, its branches and distributaries. It utilizes the tailrace discharge of Idukki Hydroelectric project by inter basin transfer and the runoff from the catchment area of Thodupuzha river up to Malankara. The Project was started in 1974 and completed in 1994 and the project envisages an ayacut of 18173 Ha of land in Kottayam, Ernakulam & Idukki Districts. The project also caters to the water needs of the Hindustan News Print factory at Velloor, near Piravom and providing drinking water facility to KWA Schemes and production of 10.5 MW of electricity at mini Hydro Electric station at Malankara.
Malankara Dam acts as a diversion structure and fully opened in rainy season and inflow into dam is not predictable as it mainly depends on KSEB power generation at Moolamattom. The out flowing water from KSEB Power house at Moolamattom after power generation is stored in this dam for irrigation and small scale power generation purposes at Malankara. However in rainy seasons 2 rivers namely Nachar and Vadakkanar in the catchment area also contributes to the inflowing water to this dam. Since the storage capacity of dam is low, dam shutters are opened in a controlled manner in order to control the inflowing huge amount of water from above mentioned 3 areas. Also if the power generation at KSEB Moolamattom is at its maximum its tail discharge is enough to take the dam to its full storage level. The O&M Manual is prepared based on the available data from existing DPR and from mechanical department as per the framework of CWC on ‘Guidelines for preparing Operation and Maintenance Manual for Dams dated Jan 2018.
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CONTENTS
Sl.no Details Page 1 General Information 1 1.1 Purpose, Location, Description of dam 1 1.2 Assignment of responsibility 11 1.3 Collection & Reporting of Dam and Reservoir Data 16 1.4 Public Utilities and Safety 17 1.5 Restricted Areas 17 1.6 Staff position, Communication & Warning System 18 1.7 Distribution of Operation & Maintenance Manuals 18 1.8 Supporting Documents & Reference Material 20 1.9 Typical Schedule of Duties 20 1.10 Hydro mechanical Inspections/ checks 24 2 Project Operation 25 2.1 Operation Plan 25 2.2 Normal Operation 25 2.2.1 Instructions for Operating Control Mechanisms 25 2.2.2 Operation of the Reservoir 29 2.2.3 Safety Aspects 30 2.2.4 Flood Release Procedure 31 2.2.5 Reservoir Capacities 31 2.2.6 Inflow forecasting 33 2.3 Emergency Operation 35 2.3.1 Flood communication system 35 2.4 Drawdown Facility 36 2.5 Record Keeping 36 3 Project Inspection 38 3.1 Types of Inspections 38 3.2 Informal Inspections 38 3.3 Scheduled Inspections 39 3.4 Special (Unscheduled) Inspections 40 3.5 Comprehensive Evaluation Inspections 41 3.5.1 General. 41 3.5.2 Details to be provided to DSRP before inspection 42 3.5.3 Field Inspection – Observations & Recommendations 43 regarding Remedial Measures 3.5.4 Components involved 45 4 Project Maintenance 47 4.1 Maintenance Plan 47 4.2 Maintenance Priorities 47 4.2.1 Immediate Maintenance 48 4.2.2 Preventive Maintenance 48 4.3 Maintenance Items 50 4.3.1 Earthwork 50 vi
O&M Manual of Malankara Dam August 2020
4.3.2 Upstream Riprap 52 4.3.3 Controlling Vegetation 53 4.3.4 Controlling Animal Damage 54 4.3.5 Controlling Ants and Termites (White Ants) 54 4.3.6 Controlling Damage from Vehicular Traffic 55 4.3.7 Masonry/Concrete dams & Spillways 55 4.3.8 Outlet Works 56 4.3.9 Trash Racks 57 4.3.10 Gates & Hoisting Equipment 57 4.3.11 Electrical System 74 4.3.12 Metal Component Maintenance 75 4.3.13 Access Roads 75 4.3.14 General Cleaning 75 4.4 Materials requirements for maintenance during monsoon period 76 4.5 Establishment Requirements 76 4.6 Preparation of O&M budget 77 4.7 Maintenance Records 80 5 Instrumentation and Monitoring 82 5.1 General Instrument Type 83 5.2 Instrumentation at Malankara Dam 83 5.3 Frequency of Monitoring 83 5.4 Data Processing and Evaluation 83 5.4.1 Data Collection 83 5.4.2 Data Presentation 83 5.4.3 Data Interpretation 83 5.4.4 Dam Performance Evaluation 84 5.4.5 Methods of Behavior Prediction 85 5.5 Visual Observations 85 6 Previous Rehabilitation reports 86 7 Updating the Manual 93 Annexure A-Basic Drawing 94 Annexure B-Hydrologic Review Report 96 Annexure C- Gate Manufacturer’s Manual 110 Annexure D- Check list for Inspection 110 Annexure E- DSRP Inspection Report 147 Annexure F- Pre monsoon Inspection Report 240 Annexure G-notification for strengthening of alarm and warning system 276 for safety of people from sudden release of water from dams issued by National Disaster Management Authority (October 2015) Annexure H-Glossary 280
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LIST OF FIGURES
Figure 1. 1. Location Map of Malnakara Dam ...... 3
Figure 1. 2. Vicinity Map ...... 4
Figure 1. 3. Catchment area of Malankara dam ...... 5
Figure 1. 4. Google Map ...... 6
Figure 1. 5. View from river side with all shutters open ...... 7
Figure 1. 6. Platform for shutter operations ...... 8
Figure 1. 7. Spillway gate ...... 8
Figure 1. 8. Stilling basin ( View from dam top ) ...... 9
Figure 1. 9. Toe Drain ...... 9
Figure 1. 10. View inside Gallery ( V notch and drain ) ...... 10
Figure 6. 1. OFFICE BUILDING ...... 87
Figure 6. 2.FENCING ...... 88
Figure 6. 3.GALLERY ...... 89
Figure 6. 4. MAIN GATE AND SECURITY ROOM ...... 90
Figure 6. 5.LIGHTING ...... 91
Figure 6. 6. River training wall ...... 92
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LIST OF TABLES
Table 1. 1. Overall Responsibilities for Malankara Dam ...... 12
Table 1. 2. Organization Chart ...... 18
Table 1. 3. Distribution of O&M Manual and Revisions ...... 19
Table 1. 4. Schedule of duties / inspections: ...... 20
Table 3. 1. Schedule of inspections ...... 40
Table 4. 1. LUBRICATION CHART ...... 67
Table 4. 2. O&M BUDGET COSTS (ANNUAL) ...... 78
Table 5. 1 Instrumentation proposed in Malankara dam ...... 85
Table 6. 1. Details of DRIP works ...... 86
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O&M Manual of Malankara Dam August 2020
ABBREVIATIONS
BIS Bureau of Indian Standards
CDSO Central Dam Safety Organisation CWC Central Water Commission SDSO State Dam Safety Organisation O & M Operation and Maintenance DRIP Dam Rehabilitation and Improvement Project DSRP Dam Safety Review Panel DTM Digital Terrain Model EAP Emergency Action Plan FMIS Flood Management Information System GPS Global Positioning System (uses GPRS for data transmission like browsing the web) FRL Full Reservoir Level MWL Maximum Water Level MDDL Minimum Draw Down Level DSL Dead Storage Level RT-DAS Real Time Data Acquisition system SCADA Supervisory Control and Data Acquisition DDMS Dam Deformation Monitoring System EDA Energy Dissipation Arrangement HM works Hydro-Mechanical works DG set Diesel Generator set ADAS Automated Data Acquisition System RMU Remote Monitoring Unit PC Personal Computer
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O&M Manual of Malankara Dam August 2020
CHAPTER1- GENERAL INFORMATION
This document represents a detailed Operation and Maintenance (O&M) Manual for Malankara Dam, Kerala, providing written descriptions of procedures for ensuring that the dam operates safely and is kept in a good condition by periodic inspections, repairs, and maintenance in a sustainable manner. Timely maintenance is important for the continued safe functioning and productive use of the dam and reservoir.
The Manual has been prepared primarily for the dam operation’s staff and their supervisors who are assigned the responsibility for the physical operations and maintenance of the dam. It contains, as a minimum, all information and instructions necessary for them to perform their allotted tasks in a safe manner. In addition to instructions for dam operations staff, the Manual includes all necessary instructions for other staff directly or indirectly involved in operating and maintaining the dam.
It is essential that the Manual or a copy of the Manual along with supporting data including the atlas of all drawings and manufacturer’s technical documents is available at site for ready reference.
1.1 Purpose, Location & Description of Malankara Dam Malankara Dam and Reservoir are owned and operated by Irrigation Department, Kerala. It utilizes the tailrace discharge of Idukki Hydroelectric project by inter basin transfer and the runoff from the catchment area of Thodupuzha river up to Malankara. The Malankara dam is an earth cum masonry dam across ThodupuzhaRiver, a tributary of MuvattupuzhaRiver. It is located at Muttom in Idukki district near Thodupuzha- Moolamattom road and was constructed for the Muvattupuzha Valley Irrigation Project (MVIP). The dam site is about 27 Km from Muvattupuzha town and 8 Km from Thodupuzha town. There is a network of canal system consisting of two main canals on either banks, its branches and distributaries. The Project was started in 1974 and completed in 1994 and the project envisages an ayacut of 18173 Ha of land in Kottayam, Ernakulam & Idukki Districts. The project also caters to the water needs of the Hindustan News Print factory at Velloor, near Piravom and providing
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drinking water facility to KWA Schemes and production of 10.5 MW of electricity at mini Hydro Electric station at Malankara.
Reservoir Features:
FRL : +42.00 m
MWL : +43.00 m
TBL : +45.00 m
MDDL : +28 m (river sluice level) Crest of Spillway : +36.90 m Dead storage Capacity : 27 Mm3 Live storage : 10Mm3 Gross storage Capacity : 37 Mm3
Revised Peak Flood : 2963 Cumec (SPF)
Type of Spillway : Ogee Spillway
Type of Gate : Radial
No of Bays : 6 Gates of 7.60 m (W) X 6.40 m (H)
Spillway Capacity : 1444.32 m3/s
Background Details of the Project
Muvattupuzha valley Irrigation project comprises of a storage reservoir across river Thodupuzha,a tributary of Muvattupuzha at Muttom, 8km from Thodupuzha town in Idukki district of Kerala state and two canal systems taking off from both flanks of the dam to irrigate areas in Idukki, Kottayam and Ernakulamdistricts.The original CCA of 17737 ha has been increased to 19237 ha by the addition of two lift Irrigation canals. Accordingly the original ultimate irrigation potential of 34737 ha has been increased to 37737 ha.The intensity of irrigation is 196%. The project also envisages drinking water supply to villages on both banks of the river and industrial water supply to the Hindustan Newsprint factory at Mulakulam.The Kerala state Electricity Board (KSEB) had constructed a hydel power station at
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the toe of the dam with an installed capacity of 10.5MW for generating power using surplus water after irrigation diversions.
Dam site Location: Malankara dam is situated Between Latitude 9° 37’& 100 4 north and between Longitude 76° 26’& 76 0 49’ east, in the village Muttom of Thodupuzhataluk inIdukki District of Kerala State.
Figure 1. 1. Location Map of Malnakara Dam
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Vicinity map
Figure 1. 2. Vicinity Map
Malankara Reservoir Planning: i). Catchment: Malankara dam utilizes the tailrace discharge of Idukki Hydroelectric project by inter basin transfer and the run off from the catchment area of Thodupuzha river up to Malankara. The catchment area of the Malankara dam is 153.5 sq.km. 4
O&M Manual of Malankara Dam August 2020
Figure 1. 3. Catchment area of Malankara dam ii) Storage: The dam is designed to pass a Probable Maximum flood (Standard Project Flood) of 2963 cumecs. The gross storage capacity at FRL of 42.00m is 37.00 Mm3 and live storage of 10.00 Mm3 and a dead storage of 27.00Mm3. The crest level is at R.L +36.90 m. iii) Water Spread: The water spread area at FRL of the dam is 5.66 sq.km
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Figure 1. 4. Google Map
Main Design Features and Components of Malankara Dam:
i) Components: The dam consists of a straight gravity dam of R. R Masonry on the right bank and in the river portion and earth fill in the left bank. The total length of the dam is 460m. The Earthen dam on the left 206m long has a maximum height of 12m. Masonry dam has a total length of 254 m of which 191.90m is non- overflow section and the balance 62.10 m is the overflow section. The spillway crest level is 36.90m and the top level of dam is +45.00 with a spillway section having 6 vents.
ii) Earthen Dam: The earthen dam has a maximum height of 12 m from the foundation and the top width is 6 m.
iii) Masonry non overflow section: This portion is constructed in Random rubble masonry in cement mortar 6
O&M Manual of Malankara Dam August 2020
iv) Spillway Dam Section: The spillway section is constructed in masonry portion of the dam where the construction is of cement concrete. The Shape of spillway is Ogee and the total length of spillway is 62.10 m. The spillway consists of six (6) nos. of radial type gates of size 7.6m x 6.4m and two (2) numbers of river sluice gates of size 1.5m x 2m
v) River Sluice Gates: Two (2) River Sluice Gates of size 1.5 m wide by2.0 m high are provided for Malankara dam to operate when the water level recedes below the crest level of 36.90m. Periodical maintenance such as lubrication, filling of gear oil, etc., are being done annually on a tender basis. Replacements of wire ropes and replacements of rubber seals and painting of river sluice gates are being taken up whenever required on tender basis.
vi) Irrigation Sluices: Two (2) irrigation sluices are provided of size 2.0m wide by 1.6m high and one is 0.8m wide by 1.0m high. The sluices release water for the LBMC and RBMC canals. Periodical maintenance of these gates is taken up annually on tender basis.
The photographs of Malankara dam detailing various sections are shown below:-
Figure 1. 5. View from river side with all shutters open
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Figure 1. 6. Platform for shutter operations
Figure 1. 7. Spillway gate
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Figure 1. 8. Stilling basin ( View from dam top )
Figure 1. 9. Toe Drain
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Figure 1. 10. View inside Gallery ( V notch and drain )
Salient Features of Malankara Dam Dam : Malankara Project : Moovattupuzha Valley Irrigation Project Tributary/River : Thodupuzha / Moovattupuzha Type of structure : Earth cum Masonry dam Location : Between Latitude 9° 37’& 100 4 north Between Longitude 76° 26’& 76 0 49’ east Place situated : Muttom Village/Taluk/District : Muttom / Thodupuzha / Idukki Year of completion : 1994 Classification : Major Irrigation Project Length : Masonry -254 m, Earthen - 206m Width at top : 5 m Maximum height from foundation : 23m Gross storage : 37 Mm3 Live storage : 10.00 Mm3 10
O&M Manual of Malankara Dam August 2020
Dead storage : 27.00 Mm3 Dam top level : +45 m Maximum Water Level : +43 m Full Reservoir Level : +42 m Minimum Draw Down Level : +39m (canal bed level at offtake ) Catchment area : 153.5 sq.km Water spread area at FRL : 5.66 sq.km Probable Maximum flood (Standard Project Flood) : 2963 cumec Spillway details Shape : Ogee Length : 62.10 m Type, No & size of gates : Radial type 6 nos of size 7.6mx6.4m Capacity : 1444.32 cumec Crest level : +36.9 m Sluices : River sluice 2 nos of size 1.5mx2m Canal LBMC-37.1 km& RBMC-28.337 km Utility Irrigation, power generation & water Supply to KWA Schemes Ayacut area : 18173 ha Installed capacity for power : 10.5 MW Reservoir level upto which power Production is allowed : +36 m
1.2 Assignment of Responsibility The Kerala Water Resources department is the owner and has the final authority and responsibility for the operation and maintenance of the dam. Identification of all areas of responsibilities connected with the operation and maintenance of the dam are covered in this section. The officer’s responsibilities for the various functions are identified by their designation and in particular, the responsibilities of operating personnel are specifically
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identified in below and includes regularly scheduled duties which staff personnel are required to perform as outlined in the following tables: Table 1. 1. Overall Responsibilities for Malankara Dam
Sl No Particulars Remarks
1 Implementing Agency Water Recourses Department, Kerala 2 Operations of Equipment at the Dam Chief Engineer, IDRB, Trivandrum, Kerala 3 Reservoir inflow and Flood Executive Engineer, MVIP Division No III, Forecasting Muvattupuzha 4 Authorizing spillway flood releases Chief Engineer, IDRB, Trivandrum, Kerala 5 Authorizing releases for various Chief Engineer, IDRB, Trivandrum, Kerala purposes like irrigation, water supply hydro-power, etc. 6 Recording reservoir Data Executive Engineer, MVIP Division No III, Muvattupuzha 7 Routine inspection Executive Engineer, MVIP Division No III, Muvattupuzha 8 Maintenance Executive Engineer, MVIP Division No III, Muvattupuzha 9 Instrumentation Executive Engineer, MVIP Division No III, Muvattupuzha
1.2.1 Roles and Responsibilities of the AEE and AE during Monsoon. Step Flood condition assessment, warning, flood mitigation, and other responsibilities 1 Coordinate with the Engineers of the KSEBL Idukki to get the information in email on the tailrace discharge during power generation in Idukki Hydroelectric project and with Engineers of the State of Kerala to get rainfall information in the catchment and inflow status at the state and to bring it to the notice of the EE/SE/CE 2 Assist the EE/SE/CE to issue notification to the villagers downstream in Newspapers, Radio, TV News channel to be alert regarding the flood situation 12
O&M Manual of Malankara Dam August 2020
3 Assist the EE/SE/CE to coordinate with the Revenue authorities (District Administration) to alert the downstream villagers to evacuate the flood zone to prevent loss of life and livestock 4 Assist the EE/SE/CE to coordinate with the CWC flood monitoring authorities on the flood condition 5 Maintain the reservoir water level register and to update on hourly basis during floods. and to bring to the notice of EE/SE/CE 6 Assess the inflows in the reservoir as per the approved reservoir operation and to prepare proforma consisting of the status of the reservoir capacity and releases from the reservoiras per the standard Performa and to submit to the EE/SE/CE 7 Submit to the EE/SE/CE on the inflows and releases from the reservoir and status of the reservoir twice in the day 8 Maintain the spillway crest gate operation log book 9 Operate the Spillway crest gates for flood mitigation as per the instructions of the EE/SE/CE and to update the Gate operation Log book 10 Observe the seepages in the drainage Gallery with respect to the reservoir head and record the seepages in the infiltration gallery and to immediately bring to the notice of the EE/SE/CE in case of excessive seepage, leakage in any specific blocks and porous drains 11 Maintain the pump operation log books for the dewatering pumps in the drainage gallery and to submit to EE/SE/CE 12 Observe the gates and to see that the drain holes are not clogged and floating debris is not deposited in the gate components 13 Monitor the condition of the Welding transformers, gas cutting sets, umbrellas, tool kits torches chain blocks ropes etc. on daily basis and to see that things are in place to handle any emergency situation 14 Observe the Gates, hoists and handling equipment during operation for the smooth movements and to immediately report any untoward excessive sounds in the motors, pumps or vibrations in the gate
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O&M Manual of Malankara Dam August 2020
15 Observe the dam top, embankment, catwalk, approach roads are well maintained by housekeeping Personnel 16 Observe the performance of the Dam and its appurtenant structures / Gates and Hoists during flood water releases and to report to the EE/SE/CE in case of any untoward incidents or malfunctioning of the gates of excessive seepages, leakages etc. 17 Assist EE/SE/CE to coordinate with the downstream Malankara Hydroelectric Project to get the power generation details 18 Assist EE/SE/CE to share the flow data and the reservoir storage details to the Media on day to day basis
1.2.2 Roles and Responsibilities of the SE and EE during Monsoon Step Flood condition assessment, warning, flood mitigation and other responsibilities 1 Coordinate with the Engineers of the KSEBL Idukki to get the information in email on the tailrace discharge during power generation in Idukki Hydroelectric project and with Engineers of the State of Kerala to get rainfall information in the catchment and inflow status at the state and to bring it to the notice of the CE 2 To issue notification to the villagers downstream in Newspapers, Radio, TV News channel to be alert regarding the flood situation 3 Assist the CE to coordinate with the Revenue authorities (District Administration) to alert the downstream villagers to evacuate the flood zone to prevent loss of life and live stock 4 Assist the CE to coordinate with the CWC flood monitoring authorities on the flood condition 5 Submit to the CE on the inflows and releases from the reservoir and status of the reservoir twice in the day 6 Operate the Spillway crest gates for flood mitigation as per the instructions of the CE and to update the Gate operation Log book 7 Observe the seepages in the drainage Gallery with respect to the reservoir head and record the seepages in the infiltration gallery and to immediately bring to the
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notice of the CE in case of excessive seepage, leakage in any specific blocks and porous drains 8 Observe the Gates, hoists and handling equipment during operation for the smooth movements and to immediately report any untoward excessive sounds in the motors, pumps or vibrations in the gate 9 Observe the dam top, embankment, catwalk, approach roads are well maintained by housekeeping personnel 10 Observe the performance of the Dam and its appurtenant structures / Gates and Hoists during flood water releases and to report to the CE in case of any untoward incidents or malfunctioning of the gates of excessive seepages, leakages etc. 11 Assist CE to share the flow data and the reservoir storage details to the Media on day to day basis
1.2.3 Roles and Responsibilities of the Chief Engineer during Monsoon Step Flood condition assessment, warning and flood mitigation 1 To issue notification to the villagers downstream in Newspapers, Radio, TV News channel to be alert regarding the flood situation based on the input by Project Engineers of the State of Kerala, to the information on the rainfall in the catchment and inflow status at the state and also to Coordinate with the Revenue authorities (District Administration) 2 Coordinate with the CWC flood monitoring authorities on the flood condition 3 Issue necessary instructions to the engineers to Operate the reservoir based on the inflows, rainfall data, releases from the upstream reservoirs and status of the reservoir 4 Observe the performance of the Dam and its appurtenant structures / Gates and Hoists during flood water releases and to issue necessary instructions to the AEE/EE/SE 5 Coordinate with the downstream Dam Project Engineers 6 Conduct Pre and Post Monsoon inspections of the Dam
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1.3 Collection &Reporting of Dam and Reservoir Data
A proforma is provided to ensure that dates and times for the collection and reporting of vital information is recorded and documented for the record.
. Reservoir water surface elevation.
. Reservoir inflow. . Spillway outflow. . River releases. . Irrigation, water supply and hydropower releases . Weather related data . Instrumentation data . Water quality
Records_[Logbooks]of the following operations at Malankara Dam are maintained in a
Chronological manner for reference. These records are helpful for identifying preventative maintenance measures that may need to be taken up, troubleshooting the cause of potential equipment failure and documenting development of any unusual conditions.
. Date and Time Attendance statement during normal operations–both during monsoon and non- monsoon periods. Operations of the spillway gates and outlet works. . Operating hours of mechanical equipment. . Testing/Operation of spillway gates, stop-logs and associated controls. . Testing/operation of Outlet gates, valves and associated controls, . Maintenance activities carried out. . Reservoir and dam inspections. . Unusual conditions or occurrences, including acts of vandalism. . Attendance statement at the dam during emergency operations. 16
O&M Manual of Malankara Dam August 2020
. Changes to normal operating procedures.
. Communication network checks.
. Safety and special instructions. . Names of officers and staff carrying out inspections and maintenance. . Any other item pertaining to the operation and maintenance of the dam.
1.4 Public Utilities and Safety
As safety of Project Staff is of prime concern, safety instructions & protection measures at the dam are carried out by all staff/project personnel. Security kiosks/cabins are located at various entrances of dam to keep an eye on the safety of staff and public in downstream. Following public utilities, with approximate distances involved, are: Medical dispensary- 1.20 km Police station- 1.00km Safety equipment Centre 1.5 Restricted Areas
The entire premises of Malankara dam area is restricted for entry of the general public as of now. Once the tourism projects are established the entry of public to dam premises will be permitted but not to these high risk areas as detailed below: - Confined spaces such as audits, inspection gallery etc. Spillway approach areas, stilling basin. Canal sluice areas, near hydro mechanical equipment etc.
The purpose of restrictions is for security of the dam, public safety and uninterrupted safe operation of the dam. Details of the Security arrangements at Malankara Dam Site.
The security arrangements of Malankara Dam are entrusted to the Kerala State Police Force inclusive of:-
One Security Officer of the rank of police inspector is in charge of the overall security arrangements
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Security personnel / Police constables (2nos) (Both armed ) are deployed 24/7 at the critical location viz., dam main entrances, control room etc. 1.6 Staff Position, Communication &Warning System
Staff positions vary according to requirement during monsoon/non-monsoon periods.
The means of communications both in normal and emergency situations are identified in the Communication Directory. Available communication includes landline, internet and mobile phones in and around dam premises. Table 1. 2. Organization Chart
ChiefEngineer , (I & D ), Trivandrum Chief Engineer, Projects – II , Trivandrum Ph : 0471 -2734001 Mob: 9497173007 Mob : 9447780159
SuperintendingEngineer, Project Circle Moovatupuzha Ph : 9744137357
Executive Engineer, MVIP Division No III , Moovatupuzha Ph : 9744137357
Asst. Executive Engineer, MVIP Sub Division I , Muttom Ph : 9447149212
Asst. Engineer, MVIP Section 2/1 , Muttom Ph :9495061339
1.7 Distribution of Operation and Maintenance Manuals The list of unit officers to whom the O&M Manual is required to be distributed is shown in the table below.
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Table 1. 3. Distribution of O&M Manual and Revisions
Sl Unit Officers Number of Manual No Distribution
1 Secretary to Govt, Water Resources Department, 3 Thiruvanathapuram 2 Chief Engineer, (I&A), Thiruvanathapuram 1 3 Chief Engineer, P2, Thiruvanathapuram 1 4 Chief Engineer , IDRB , Thiruvananthapuram 1 5 Central Dam Safety Organisation 1
6 State Dam Safety Organisation 1
7 National Disaster Management Authority 1
8 State Emergency Operation Center, Kerala Disaster 1 Management Authority
9 District Collector, Idukki 1
10 District Collector, Ernakulam 1 11 District Collector, Kottayam 1 12 District Police Chief, Idukki 1
13 District Police Chief, Ernakulam 1 14 District Police Chief, Kottayam 1 15 Superintending Engineer, Project Circle Moovatupuzha 1 16 Executive Engineer, MVIP Div III , Moovatupuzha 1 17 JD , IDRB, Thiruvanathapuram 1 18 Assistant Executive Engineer,MVIP Subdivision No 1 1,Muttom 19 Assistant Executive Engineer, Mechanical 1 Subdivision,Thodupuzha 20 Assistant Engineer, MVIP Section2/1 , Muttom 1
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1.8 Supporting documents and Reference Manual
This O&M Manual is the key instruction document. Supporting documents and necessary instructions for all phases of the operation, inspection and maintenance of the dam, reservoir and appurtenant works shown below are available at the dam control room: Emergency Action Plan (EAP).
Flood forecasting and operating criteria.
Basin or river operating plan.
Irrigation operating instructions.
Administrative procedures.
Dam site security plan
Maintenance Schedules
Manufacturer s instructions & drawings.
Guideline for Safety Inspection of dams
Regional communications directory for dams
1.9 Typical schedule of duties
Schedules of duties being performed by the staff assigned to various locations and components of Malankara Dam are provided in this section. All activities are to be recorded daily in the Log book and site registers. Table 1. 4. Schedule of duties / inspections:
SL Component / Duty Frequency Personnel NO 1 Visual inspection of dam including Crest Daily Assistant Engineer of dam (Dam top), Upstream and / Dam operators downstream faces, visible portions of on contract
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foundation and abutments, Galleries, Spillway and its energy dissipation arrangements, sluices etc. 2 Record water surface elevation, reservoir Daily ( Hourly basis Assistant Engineer inflow and spillway discharge. during monsoon) / Dam operators on contract 3 Record meteorological data, Record Daily Assistant Engineer releases from canal sluices / Dam operators on contract. 4 Check security and safety devices, Daily Assistant Engineer Complete log book / site register which include the above information 5 Record seepage from drainage systems, Weekly Assistant Engineer Gallery drains etc. and record / Dam operators in meteorological date contract 6 Visual inspection of dam including Crest Weekly Assistant Engineer of dam ( Dam top, Upstream and down stream faces visible potions of foundation and abutments, Galleries, Spillway and its energy dissipation arrangements, canal sluices etc. 7 Check stand by generator (DG Sets), Weekly Assistant Executive Drainage systems, Gallery drains etc. Engineer
8 Visual inspection of dam including crest Fort nightly Assistant Executive of dam (Dam top), Upstream and down Engineer stream faces, visible portions of foundation and abutments, Galleries, Spillway and its energy dissipation arrangements, canal sluices etc.
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9 Check security and safety devices, log Fort nightly Assistant Executive book and site register which include the Engineer above information 10 Check standby generator (DG Sets), Fort nightly Assistant Executive Drainage systems, Toe drains and Gallery Engineer drains 11 Measuring devices, communication Fort nightly Assistant Executive devices, status of instruments, Engineer vegetation growth 12 Check Sign / Warning display boards near Fort nightly Executive Engineer vulnerable locations 13 Visual inspection of dam including crest Monthly Executive Engineer of dam (Dam top), Upstream and down stream faces, visible portions of foundation and abutments, Galleries, Spillway and its energy dissipation arrangements, canal sluices etc. 14 Check measuring devices / Instruments, Monthly Executive Engineer Security and safety devices, Communication Devices, Status of Vegetation growth, rectification, if needed 15 Check Sign / Warning display boards near Monthly Executive Engineer vulnerable locations 16 Replace fuse light bulbs, Inspect to Monthly Assistant Engineer Maintain ventilation system, cleaning of control panel boards. 17 Check outlet works, updating operating Quarterly Executive Engineer instruction, check gate air vents, clean gate control switchboxes, check
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operation of gates, grease gate hanger / dogging 18 Check condition of canal sluice works and Quarterly Executive Engineer its d/s structure, Check operation of Emergency gate and regulation gates for canal sluices 19 Check condition of spillway structure, Quarterly Executive Engineer Check for debris in inlet channel, Check operation of spillway gates, check for damages in spillway glacis, energy dissipation arrangement, d/s area etc., Check and clear spillway bridge drains, check various operations being conducted from control room etc. 20 Check for adherence to instrumentation Quarterly Executive Engineer schedule, Record pertinent information in operation of Gates, Check condition of V notch / seepage measuring devices, Check hydro mechanical components. 21 Inspection of Spillway and outer works, Half Yearly ( pre Superintending hydro mechanical components, Check and post Monsoon) Engineer along paint on gates, Check lubrication of wire with Executive ropes etc. and application of cardamom Engineer in charge compound, Check mechanical hoist of dam bearings and flexible coupling bearings, Check gear systems, Exercise gates, Check lubrication of gate rollers, Check rubber seals and seal clamp bar. 22 Submission of Inspection report to state Half Yearly Chief Engineer / DSO, CWC and uploading into DHARMA Superintending
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Engineer 23 Comprehensive inspections Annually Dam Safety Authority along with Dam Owners 24 Inspect dam and gate structures, energy Five Yearly Chief Engineer / dissipation arrangement, which normally Superintending are underwater ( by dewatering or by Engineer divers). Review Dam operation procedures and EAP and update as necessary 25 Comprehensive inspection of Ten Yearly DSRP performance of the dam and gate structures and reservoirs, energy dissipation arrangement and allied structures including dam operating systems
1.10 Hydro-Mechanical Inspections / Checks Frequent inspections / checks for hydro-mechanical components are to be conducted and necessary action to be taken up during maintenance. Routine maintenance is carried out for spillway gates, intake gates and outlet valve as pare of routine maintenance before the onset of monsoon. Details are given under the chapter-Project Maintenance
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CHAPTER2- PROJECT OPERATION
The Malankara operation plan consists of step-by-step instructions for operating the dam and reservoir during routine (normal) and emergency conditions. The operating procedures for normal operations are discussed in this chapter including operating criteria for the reservoir, spillway & outlets. The operation of a dam involves regulation of its reservoir as per project specific requirements. This includes the use of area capacity curves and design flood; both are described below.
2.1 Operation Plan Operation plan consists of step-by-step instructions for operating the dam and reservoir. Operating procedures are developed based on:
Reservoir operation studies, relevant design documents, hydraulic model studies etc. Equipment Operating and Maintenance Instructions (Manufacturers' Instructions) Operating procedures are to be developed for both normal operations and emergency operations.
2.2 Normal operations
The operating procedures developed for normal or day to day operation of a dam shall include the following. 2.2.1 Instructions for operating control mechanisms
The Gates are operated by rope and winch mechanism hoists having a lifting capacity of 15 T. The hoists are capable of fully opening or fully closing the gates holding them fully opened or in any intermediate position, during either the opening or closing operation. The limits witches mounted on each hoist unit are set to stop the hoist automatically when the units reach the fully opened or fully closed position. Each hoist can be operated from the unit control cabinet locatedin the hoist operating unit fitted on the operating platform. Each control panel contains the
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necessary maininter-locking arrangement is provided to dis-engage the hoist machinery from electric circuit when manual operation is in progress. 2.2.1.1 Recommended Gate Operation Procedures for Normal Flow Conditions Malankara dam act as a diversion structure and fully opened in rainy season and inflow into dam is not predictable as it mainly depends on KSEB power generation at Moolamattom. Also if the power generation at KSEB Moolamattom is at its maximum its tail discharge is enough to take the dam to its full storage level.
The procedure of shutter opening will be done only after giving proper intimations to Disaster Management Cell at Idukki Collectorate, Disaster Management Cell at Ernakulam Collectorate, Taluk office at Thodupuzha & Muvattupuzha, police stations at Thodupuzha & Muttom, higher officers of Irrigation Department, concerned LSGD Institutions, local visual and new medias and only in the presence of concerned Assistant Executive Engineer, Assistant Engineer, as per the order from Executive Engineer. 2.2.1.2 Operation of spillway Radial Gates of Malankara Dam
Radial Gates· of Malankara Dam have been designed with spillway crest of 36.90m and FRL of 42m. The basic principal of the design is that. The water pressure is transferred to piers and abutmentsthrough skin plates, stiffeners horizontal girders, arms, trunion, tie flats and anchor girders. The skin plates between bottom and top horizontal girders is designed as supported on the girders. The portion below the bottom horizontal girder up to sill beam and above top horizontal girder and up to FRL is designed as cantilever. Spillway Radial Gates–Technical Data
1.The spillway Radial Gate consist of an upstream curved skin plate of varying thickness 10mm, stiffened by suitably spaced vertical 600 ISMB stiffeners. 2.Thesill beam, wall plates are provided with suitable anchorage for a rigid connection to the spillway crest and the piers Suitable stainless steel plates are welded on the wall plate to match with the rubber seals. The sill beam embedded in the spillway crest are provided sealing surfaces of stainless steel to match with the rubber seal on the bottom of the gates
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3.The gate consists of structural steel frame formed by two (2) main horizontal girders supported by radial arms at each end. These inclined radial arms in turn transmit the load to trunnion brackets installed on trunnion girder spanning between the piers. The water load is transferred through girders to end arms, trunnion brackets, to concrete beam and is finally transferred to pier concrete. 4.Gate Assembly The skin plate of the gate consists of a 10mm-thick stainless steel on the u/s side. The skin plate is stiffened by radial shaped vertical stiffenersresting on horizontal girders. The- vertical stiffeners rest on horizontal girders which are mounted on suitably braced inclined arms fixed to the trunnion assembly. The skin plate is supported on 2 main horizontal girders which are in turn, supported on a frame of inclined arms. The end arms pivot on trunnion pins mounted on trunnion brackets fixed to the Yoke girder and resting on rest beam (chair) plate. The water load is transferred to pier concrete through Anchor bars welded to anchor girder embedded in pier concrete. The horizontal force due to arm inclination is taken by stiffened D/s flange of horizontal girder at the junction level. This force is taken by the trunnion tie connecting the two trunnion hub limbs. 5.Guide Roller Assembly Each gate has been provided with 2 guide rollers of size dia150-mm O.D.x70mmI.D.x 50mm width on each side, to check side sway. In fully open position of the gate, two no. guide rollers on each side rest on the wall plate. The rollers are provided with copper bronze bushings turning on fixed pins. The roller pin is 50-mm-dia and 90mm length and is hard chromium-plated with thickness of 40 microns. The rollers are fixed with keeper plate and washers. 6.Trunnion Assembly The trunnion assembly consists of a single piece cast steel trunnion hub having 270 mm and 320mm, to which the arms of the gates are rigidly connected to ensure full transfer of load. 580-dia. stainless steel trunnion pins with bush bearings of size 180I.D. x 220O.D and length 320mm. are used. The trunnion pins are hard chromium plated to 40 micron. The trunnion pin connect trunnion hub to radial arms.
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7.Seal Arrangement The radial gate is seated at the bottom by contact of bottom edge of skin plate and flat type bottom seal of 12-mm-thickness and side seals of thickness 15mm,100mm width and radius 22mm (musical note Type).
Hoisting Arrangements for Radial Gates The main component of hoisting system for operation of the radial gates of spillway consists of rope and winch mechanism driven by 5HP AC induction motor through reduction gear box with electromagnetic break system mounted on top of the pier downstream of the spillway hosting Platform Bridge. The hoisting system is provided with dial indicator assembly with limit switches to cut off power supply when the gate reaches the specified position.
Salient Features
Sl.No. Feature Description i. Type of gate Spillway Radial gate ii. Size of Gate 7.6m x6.4m iii. No. of Gates 6Nos(Gate1to6) iv. Clear width of opening 7.67m
2.2.1.3 Check list before operation The following steps are to be taken before operation of the gates to ensure these eight critical functions are in good working condition. Step 1 Seal Clamp The seal clamp fixing should be such as to ensure that the side seals are flexible enough Step 2 Limit Switch Limit Switches shall be checked for satisfactory operation (function) to stop the hoist automatically, when the gate reaches the fully opened or fully closed position Step 3 Nut & Bolts All nuts, bolts and screws shall be checked for wear, 28
O&M Manual of Malankara Dam August 2020
tear and tightness Step 4 Pins Gate pin, connecting pin and all other pins should be in proper position and ensure that the nuts and split pins are tight and proper Step 5 Trunnion Lubrication To check and apply the high pressure lubricating grease in trunnion bushing from the hole provided in trunnion hub Step 6 Control Panel Control Panel shall be checked for its suitability for the purpose envisaged. The check may include items such as weather proofing, conducting wires, etc. In case of any contact chatter, clean the magnet surface and try again. If the chattering continues, check the coil voltage and replace the contact / coil, if necessary
2.2.2 Operation of the Reservoir The general operation of the reservoir, including monitoring and regulation of inflow and outflow are included in this section. Inflow includes upstream dam release, flood water, etc. Out flow includes the releases from the dam for specific release and the date and duration of such releases. Gate operation sequence, maximum release that can be made, various reservoir levels, etc. affect the operation of reservoir. Operation of reservoir should include reservoir capacities at different levels, monsoon yields, and proposed reservoir levels during monsoon months, release of surplus water, etc. With the experience and past records, the reservoir operation rules should be so formulated by the field officers so that reservoir levels are so maintained that the incoming flood water can be stored at FRL. The release pattern of flood water is to be maintained so that no harm to the downside area occurs and should be done after giving due warning. The rainfall pattern is to be closely monitored so as to modify the rules accordingly.
2.2.2.1 Rule curve Malankara dam act as a diversion structure and and inflow into dam is not predictable as it mainly depends on KSEB power generation at Moolamattom. The out flowing water from
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KSEB Power house at Moolamattom after power generation is stored in this dam for irrigation and small scale power generation purposes at Malankara. However, in rainy seasons 2 rivers namely Nachar and Vadakkanar in the catchment area also contributes to the inflowing water to this dam. Since the storage capacity of dam is low, dam shutters are opened in a controlled manner in order to control the inflowing huge amount of water from above mentioned 3 areas. Also if the power generation at KSEB Moolamattom is at its maximum its tail discharge is enough to take the dam to its full storage level. Malankara dam is operated mainly for 3m water level. Since the Inflow to this dam is not predictable as it mainly depends on KSEB power generation, rule curve for this dam also has no importance. (Minutes on the Discussion and Presentation on Rule Curve on 16-10-2018 in the Board Room, IDRB, Trivandrum)
2.2.3 Safety aspects The public safety is of paramount importance at Malankara dam and reservoir. The general instructions in this regard are as under: State procedures to be followed for restricting access to the dam or confining traffic to designated areas. Indicate the procedures to be followed when tourists visit the facility. Designate speed limits to keep the traffic within acceptable and safe limits. Establish standards for maintaining sanitary conditions. Prevent contamination or pollution of water for human consumption and/or re- creational use. Eliminate safety hazards by: - Posting warning signs. - Removing unsafe conditions where possible. - Restricting public access to chutes, stilling basins, and control rooms. - Posting safety instructions at visible and key locations. - Providing adequate security. Ensure provision of all downstream warning systems like sirens, hooters etc. An adequate system of giving information into downstream areas regarding release of flood outflows from spillway should be there. 30
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At the same time instructions regarding operations, inspection and maintenance need to be strictly followed for ensuring safe operation of the dam.
2.2.4 Flood release procedures
The first warning level of dam is at 40.70 m, second warning level is at 41.00 m and third warning level is at 41.30 m. The opening of shutters at each warning level will be informed to the concerned authorities. Due to small storage capacity the three warning levels is attained at very short intervals. Total number of shutters are six and will be opened in the order as shown below. The 4th shutter will be opened first, followed by 3rd shutter, followed by 5th shutter followed by 2nd, 6th and 1st from left abutment facing downstream. The flood regulation procedures at dam can be summarized in the following 5 steps: · Observe the reservoir level at 1 hour intervals. Determine the total outflow occurring at all outlets (including river sluices, canals, spillway, turbines) Estimate the inflow Determine the gate opening Open all 6 gates to the extent required by step in the proper sequence as described. The gates are operated to maintain constant reservoir level +39.50m Discharge through spillway at different shutter opening and warning levels are shown below
Design Flood and Moderated Flood The existing spillway for Muvattupuzha vally Irrigation Project was designed for original flood of 1444.32 m3/s. The revised design flood (SPF) has been worked out to be 1948 m3/s as per the design flood review study by CWC on June 2020. The flood routing studies for revised value of design flood is to be conducted.
2.2.5 Reservoir capacities
The capacity of reservoir at FRL (+42m) is 37 Mm3. Live storage is 10 Mm3 and Dead storage is 27 Mm3 2.2.5.1 Area Capacity curves.
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The area capacity curves for Malankara Dam areshownbelow
Elevation (m) Surface Area (Ha)
38.00 320
39.00 360
40.00 380
41.00 420
42.00 460
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2.2.6 Inflow forecasting
The gross storage of Malankara Dam at FRL 42m is 38Mm3. The Malankara have been designed for a SPF of 2963 cumecs. It acts as a diversion structure and fully opened in rainy season and inflow into dam is not predictable as it mainly depends on KSEB power generation at Moolamattom. The out flowing water from KSEB Power house at Moolamattom after power generation is stored in this dam for irrigation and small scale power generation purposes at Malankara. However in rainy seasons 2 rivers namely Nachar and Vadakkanar in the catchment area also contributes to the inflowing water to this dam. Since the storage capacity of dam is low, dam shutters are opened in a controlled manner in order to control the inflowing huge amount of water from above mentioned 3 areas. Also if the power generation at KSEB Moolamattom is at its maximum its tail discharge is enough to take the dam to its full storage level.
During monsoon, incident rains in the catchment area and also the power generation at KSEB Moolamattom causesthe flash floods in Thodupuzha River. These floods may lead to problems like people getting displaced from their homes, huge damage to crops and other assets. The floods can have disastrous impact on the environment also. Adequate
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measures are required to be taken up in advance to control and regulate the flow of water in the river.
The following measures are essential for effective management of floods in River during the monsoons.
1. Nomination of liaising officers for respective reservoirs.
2. Sharing of Sub-basin wise directory of concerned officers responsible for flood management.
3. Exchange of data regarding rainfall, releases from dams, and reservoirwater levels for projects located u/s of this dam. 4. Reservoir operation schedules for u/ s projects. The Muvattupuzha Valley Irrigation Project has established office at Malankara during 1994. Based on the tailrace discharge from Moolamattom Power house, rainfall in the catchment and flow in the river and tributaries, Malankara office will furnish flood forecasting reports.
The list of rain gauges in the catchment Muvattupuzha river basin and daily rainfall is to be collected from hydrology department. It will helpful for prediction of probable floods in the river.
During monsoon daily water releases from the Dams/Barrages at 24 hrs in normal situation and hourly data exchange during heavy floods is necessary. In this regard, the data is required to be established. The data regarding floods is made available to Disaster Management Cell at Idukki collectorate, Disaster Management Cell at Ernakulam collectorate, Taluk offices at Thodupuzha & Moovatupuzha , Police stations at Thodupuzha and Muttom , higher offices of irrigation department , concerned LSGD offices and local visual and news medias.
Inflow Computation The rate of increase (ordecrease) in storage can be determined from the observed rate of increase (or decrease) in reservoir level and the elevation capacity tables.
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Examples of Inflow Computation Let the reservoir level be at 40.82 m at 06:00 PM, Storage= 32.62Mm3 and at 40.86 m at 07:00PM, Storage =32.84Mm3 Change in Storage= 32.84Mm3-32.62Mm3=0.22Mm3 Time interval=1.00Hrs=60min. Rate of change in storage=(0.22x1000000)/ (60*60 )=61.11m3/sec If the outflow is zero, The inflow is same as above. But If any outflow is there like spillway shutter opening, canal shutter opening etc. then the net inflow= out flow + the difference in storage difference 2.3 Emergency operations 2.3.1 Flood communication systems The widely time tested Communication to reach every corner of the flood affected zones have been radio and television and private media for the people to move to safer places by themselves in an emergency. Communication is very important in such occasions. Now a days due to revolution in the telecommunication system, availability of network of mobile phones is there. Advantage of this facility will be taken. Mobile numbers of all such staff will be listed and made available to all the personnel who have been assigned duty of disaster management. Following liaising officers for flood co-ordination of Malankara Dam are as listed below: CHIEF ENGINEER , (I & D ), TRIVANDRUM CHIEF ENGINEER , PROJECTS – II , Ph : 0471 -2734001 TRIVANDRUM Mob : 9447780159 Mob : 9497173007
SUPERINTENDING ENGINEER, PROJECT CIRCLE MOOVATUPUZHA Ph : 9744137357
EXECUTIVE ENGINEER , MVIP DIVISION NO III , MOOVATUPUZHA Ph : 9744137357
ASST. EXECUTIVE ENGINEER , MVIP SUB DIVISION I , MUTTOM
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Ph : 9447149212
ASST. ENGINEER , MVIP SECTION 2/1 , MUTTOM Ph :9495061339
2.4 Drawdown facility All water release facilities, including outlet works, sluices, gated spillways, and power penstocks should be considered available for evacuation to the extent that their reliability in an emergency situation can be reasonably certain. In the case of canal outlet works, there must be a bypass or waste way in order for such outlet works to be considered available for emergency releases. Otherwise releases through them will be considered equal to the design capacity of the canal. Reservoir level may be required to be lower level, if a critical/emergency condition occurs or for carrying out repairs to the dam on its upstream slope/face in dry condition. For general guidance the ACER Technical Memorandum no. 3 - Criteria and Guideline for evacuating storage reservoirs and sizing low level outlet works & IS: 15472 – Guidelines for planning of low level outlets for evacuating storage reservoirs may be referred to. Care is to be taken to restrict the reservoir draw down rates to prevent failure of upstream slope of the Embankment/ landslides along reservoir periphery etc. This will vary from dam to dam and project to project. The actual drawdown rates both under normal and emergency conditions have to be decided by the Dam Designers.
2.5 Record Keeping
Operating a dam includes keeping accurate records of items pertaining to project operation. These include but not limited to the following:-
1.Rainfall and Reservoir Levels–On daily basis during non-monsoon and on hourly basis during monsoon.
2.Release through outlet/sluices on daily basis for irrigation, water supply, hydropower etc. 36
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3.Outflows through spillway during monsoon on hourly basis. 4.Records of drawdown with reservoir levels, quantity of water released, drawdown rates, reason for drawdown.
5.Other Procedures–Maintain a complete record of all operating procedures for gates, sluices and remote control operating system.
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CHAPTER 3 - PROJECT INSPECTIONS
The current practice of Inspection at Malankara dam envisages the Subdivision Officers to carry out pre-monsoon and post-monsoon inspections.Detailed description on project inspections is available in the guidelines for safety inspection of dams (Doc No, CDSO GUD DS 07v1.0), CWC2018 (https://damsafety.in/ecm-includes/PDFs/Guidelines for safety Inspection of Dams. Pdf). Inspection check list for dams and allied works is enclosed as one of the annexure in the document. An overview of the various types of inspections to be carried out at Malankara dam is given below. 3.1Types of Inspections Four different types of dam safety inspections are available which can be carried out at Malankara Dam. These include, but not limited, to the following: 1. Comprehensive evaluation inspections 2. Scheduled inspections (Pre & Post monsoon inspections & other scheduled inspections) 3. Special (unscheduled) inspections 4. Informal inspections The frequency of each type of inspection depends on the condition of the dam and State DSO Regulations, etc. Typical inspection elements and the detail of the safety inspections are provided below. More detailed descriptions are given in the ‘Guideline for Safety Inspection of Dams’ (CWC 2018). 3.2 Informal Inspections An informal inspection, is a continuing effort by on-site personnel (dam owners/operators and maintenance personnel) performed during their routine duties. Informal inspections are critical to the proper operation and maintenance of the dam. They consist of frequent observations of the general appearance and functioning of the dam and appurtenant structures. Operators, maintenance crews, or other staffs who are posted at dam site conduct informal inspections. These people are the “first-line of defense” in assuring safe dam conditions, and
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it is their responsibility to be familiar with all aspects of the dam. Their vigilance in walking across the dam, checking the operating equipment, and noting changes in conditions may prevent serious mishaps or even dam failures. Informal inspections are important and are performed at every available opportunity. These inspections may only cover one or two dam components as the occasion presents itself, or they may cover the entire dam and its appurtenant structures. The informal inspections are not as detailed as comprehensive evaluation, scheduled, and special inspections and will only require that a formal report is submitted to the dam owner’s project files if a condition is detected that might endanger the dam. Report is to be submitted detailing the condition observed along with photographs, time and reservoir water level (RWL), etc. 3.3 Scheduled Inspections Scheduled inspections shall consist of Pre-monsoon & Post-monsoon inspection and any other inspections carried out by the State Dam Safety Organisation / any Expert panels constituted by the dam owner. These inspections are performed to gather information on the current condition of the dam and its appurtenant works. This information is then used to establish needed repairs and repair schedules, and to assess the safety and operational adequacy of the dam. Scheduled inspections are also performed to evaluate previous repairs. The purpose of scheduled inspections is to keep the dam and its appurtenant structures in good operating condition and to maintain a safe structure. As such, these inspections and timely maintenance will minimize long-term costs and will extend the life of the dam. Scheduled inspections are performed more frequently than comprehensive evaluation inspections to detect at an early stage any developments that may be detrimental to the dam. These inspections involve assessing operational capability as well as structural stability and detection of any problems and to correct them before the conditions worsen. The field examinations should be made by the personnel assigned responsibility for monitoring the safety of the dam. If the dam or appurtenant works have instrumentation, the individual responsible for monitoring should analyze measurements as they are received and include an evaluation of that data. Dam Inspection Report or an inspection brief should be prepared following the field visit (Dam Inspection Report is recommended).
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Scheduled inspections would include the following components as a minimum: . File review of past inspection reports, monitoring data, photographs, maintenance records, or other pertinent data as may be required; . Visual inspection of the dam and its appurtenant works; . Preparation of a report or inspection brief, with relevant documentation and photo graphs. The report should be filed in the dam owner’s project files. 3.3.1 Pre-and post-Monsoon checklist and Example of Report proforma Detailed checklists are required to ensure the health of the dam and to ensure that it continues to operate in satisfactory and safe condition. The proforma to be used for inspection should be the one enclosed in the Doc No. CDSO GUD DS 07 v1.0, CWC 2018 on the Guidelines for safety inspection of Dams and also enclosed as one of the annexures.
Table 3. 1. Schedule of inspections
Pre-monsoon Inspection to be : April - May carried out during Post-monsoon Inspection to be : December - January carried out during Submission of Pre-monsoon : Before June 30th Inspection Report
Submission of Post-monsoon : Before January 15th Inspection Report
Checking and approval of report : Deputy Chief Engineer, SPMU
Uploading corrected document in : Executive Engineer, Field(Dam Health DHARMA Engineer)
3.4 Special (Unscheduled) Inspections Special inspections may need to be performed to resolve specific concerns or conditions at the site on an unscheduled basis. Special inspections are not regularly scheduled activities, but are usually made before or immediately after the dam or appurtenant works have been subjected to unusual events or conditions, such as an unusually high flood or a significant earthquake. These inspections are to be carried out after an initial assessment based on informal inspection carried out by project personnel reveal dam safety related concerns like
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cracking in the dam, damages, erosion/ scour, undermining/ piping/ sink holes/ liquefaction or any such undesirable feature. A special inspection may also be performed during an emergency, such as an impending dam breach, to evaluate specific areas or concerns. They are also made when the ongoing surveillance program identifies a condition or a trend that appears to warrant a special evaluation. Special inspections should focus on those dam components that are affected by the unusual event and should include at least three elements: . 1) Review of relevant files or data, 2) visual inspection, and 3) report preparation. . More detailed site investigations / studies may be required (such as drilling, surveys, or seepage flow estimates) if the special inspection reveals the need for the same. Photographic documentation is to be included as part of the inspection.
3.5 Comprehensive Evaluation Inspections 3.5.1 General For comprehensive dam safety evaluation for each dam an independent panel of experts known as Dam Safety Review Panel (DSRP) needs to be constituted for determining the condition of the dam and appurtenant works. The panel will undertake evaluation of the dam once in 10 years or on occurrence of any extreme hydrological or seismic event or any unusual condition of the dam or in the reservoir rim. The terms of reference of the comprehensive dam safety evaluation shall include but not be limited to; 1. General assessment of hydrologic and hydraulic conditions, review of design flood, flood routing for revised design flood and mitigation measures. General assessment of hydrologic and hydraulic conditions, review of design flood, flood routing for revised design flood and mitigation measures. . Review and analysis of available data of dam design including seismic safety, construction, operation maintenance and performance of dam structure and appurtenant works. . Evaluation of procedures for operation, maintenance and inspection of dam and to suggest improvements / modifications.
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. Evaluation of any possible hazardous threat to the dam structure such as dam abutment slope stability failure or slope failures along the reservoir periphery. 3.5.2 Details to be provided to DSRP before inspection All relevant details/data/drawings for the dam project to be inspected by the Panel of Experts shall be provided at least 3 months in advance of the proposed visit. This will include:- (a) General Information 1. Scope of project 2. Basic data and salient features 3. Issues related to safety of dam 4. Details of key personnel 5. Emergency preparedness – Communications, Auxiliary Power, Downstream Warning system & Security of site. (b) Hydrology 1. Description of drainage basin 2. Original inflow design flood 3. Spillway capacity at FRL &originalMWL 4. Surface area & storage capacity ofthe reservoir 5. Flood routing criteria & results (c) Geology 1. Dam site geology including geological reports 2. Quality and sufficiency of the geological investigations. 3. Special problems and their treatment 4. Reservoir competency as per geological report. 5. Slope stability issues along reservoir. (d) Layout including Drawings 1. Dam 2. Spillway 3. Concrete/Masonry dams 4. River/Canal outlets 5. Instrumentation
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(e) Dam and Spillway Geology Special problems Foundation treatment including treatment of faults/shear zones/weak zones, curtain/consolidation grouting, drainage provisions, any other special treatment, cut off trench, diaphragm walls etc. Design criteria and result of stability analysis Special studies (Finite element/Dynamic Analysis etc.) Adequacy of design – from dam safety considerations Hydraulic design of Spillway and Energy Dissipation Arrangements including past model study reports Instrumentation – analysis and interpretation of instrumentation data including structural behaviour reports. Pre-construction material testing reports including adequacy of field and laboratory investigations, appropriateness of materials selected etc. Post-construction testing reports, if any. Seismicity (Seismic Parameters approved by the National Committee for Recommending Seismic Design Parameters for Dams) f) Construction history g) Dam incidents/failures, remedial measures/modifications undertaken h) Reservoir Operation & Regulation Plan 1. General 2. Reservoir filling 3. Water releases – normal and during floods. 3.5.3 Field inspection- Observations and recommendations regarding Remedial Measures Each component of the project is to be inspected; evaluated and specific problems are to be brought out. Recommendations for necessary remedial measures need to be included in the panel‘s report. Various project components to be inspected shall include but will not be limited to; (a) Dam
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1. Upstream face 2. Downstream face 3. Top of dam 4. Structural behaviour as observed visually and as per evaluation of instrumentation data (any visible cracking, deflections etc.) 5. Seepage assessment 6. Condition of natural/excavated slopes in the abutments, both on u/sand d/s of the dam. 7. Any specific problems/deficiencies (b) Spillway 1. Civil structure 2. Energy Dissipation Arrangements (EDA) 3. Spill channel, drop structures etc. If any. 4. Condition of EDA and its performance 5. Spillway Gates & Hoists 6. Downstream safe carrying capacity of river / channel. (c) River / Canal Outlets 1. Civil structures 2. Outlet Gates, Hoists & Controls 3. Conduits / Outlets through Embankment dams and sluices through Masonry / Concrete dams (Condition, problems etc.) 4. Trash racks, if any 5. Separate energy dissipation arrangements, if any. (d) Review of Sedimentation of the Reservoir. Assessment of sedimentation and its effects on flood routing, operation/life of reservoir. (e) Flood Hydrology 1. Extent & sufficiency of data available 2. Method used for estimating the design flood. 3. Design flood review study.
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4. Flood routing studies with the revised flood 5. Adequacy of free board available (f) Miscellaneous services /facilities 1. Access Roads / Bridges / Culverts 2. Elevators 3. Stand by power arrangements 4. Flood forecasting arrangements, if any 5. Communication facilities (Telephone, Satellite, Wireless, Mobile etc.) (g) Hydraulic Model studies, if any new studies carried out. (h) Earlier reports of experts / DSRP etc., if any, as annexure. (i) Photographs of dam project showing problem areas. 3.5.4 Components involved A comprehensive evaluation inspection of a dam will typically consist of five components: 1. Project records review (i.e. study of all design / construction records/drawings, history of the dam‘s performance, past inspection notes/reports, notes on distress observed/ any rehabilitation measures undertaken earlier etc.). 2. Visual inspection or field examination of the dam and its appurtenant works. 3. Preparation of a detailed report of the inspection. 4. Education and training of the dam owner on the issues observed during dam inspection, identification of potential dam failure modes & to carryout addition al field investigations & laboratory testing as required. Dam owners should be made part of the inspection process so that they take ownership of the results and are committed to implementing there commended remedial measures. 5. Design studies e.g. review of design flood, checking of the adequacy of spillway capacity, freeboard requirements, dam stability, any special study as required & submission of the report. A comprehensive evaluation inspection of dam consists of five major parts: 1. Review of project records (i.e. study of all design / construction records/drawings, history of the dam’s performance, past inspection notes/reports, notes on distress observed/ any rehabilitation measures undertaken earlier, instrumentation data and
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its interpretation including 2. Inspection of the dam and its appurtenant works. 3. To review the results and reports of additional field investigations & laboratory testing as required. 4. Review of design studies e.g. review of design flood, checking of the adequacy of spillwayCapacity, freeboard requirements, dam stability, any special study as required. 5. Preparation of a detailed report of the inspection.
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CHAPTER 4 - PROJECT MAINTENANCE
4.1 Maintenance Plan Nearly all the components of Malankara Dam including masonry portion and earthern portion and its materials are susceptible to damage and deterioration if not well maintained. Hence an ideal maintenance program has been implemented that takes care of Malankara Dam from deterioration, prolongs its life, and greatly reduce the chance of failure. Moreover, as per the principle of ‘Prevention is better than cure’ the cost of a proper maintenance program is minimal compared to the costs of major repairs, loss of life and property and litigation. Preventative maintenance not only protects the dam and its owner but the public as well. If maintenance of a dam is neglected the consequences and costs will multiply exponentially. Individual maintenance tasks are noted, with a description of the area where the maintenance is to be performed, the schedule for performing the tasks, and reporting procedures. Typical routine maintenance tasks performed includes mowing grass, removing vegetation, bushes and trees, removing litter and other debris, re-grading the crest and/or access roads, repairing fencing to keep livestock off the dam, etc. Other maintenance works that need to be performed on the embankment includes restoration of embankment to its design section, seepage problems, erosion, displaced riprap, cracking in embankment etc. In masonry dam there may be issues like cracking and disintegration in concrete, choking of drainage holes in dam body/ foundation, damages to spillway glacis/piers/energy dissipaters due to abrasion/ cavitations/unsymmetrical flows, damages to pointing on upstream & downstream faces of masonry dams, heavy seepages through some drains in foundation/inspection galleries etc. Any piping issues formed in earthen portion of dam also may be taken care of. A basic maintenance program has been arrived primarily based on systematic and frequent inspections by the higher authorities and expert panels. 4.2 Maintenance Priorities For Malankara Dam, maintenance activities require to be classified as immediate maintenance or preventative maintenance.
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4.2.1 Immediate Maintenance The below mentioned conditions are critical and require immediate attention & reservoir lowering, if warranted. These conditions may include, but are not limited to: The dam is about to be overtopped or being overtopped during high flood inflow The dam is about to be breached by erosion, slope failure etc. The dam showing signs of piping or internal erosion indicated by increasingly cloudy seepage or other symptoms. The spillway being blocked or with some inoperable gates or any obstructed materials in shutter Evidence of excessive seepage appearing anywhere on the dam site ,e.g., the Embankment becomes saturated, defective water stops, etc., and seepage exiting on the downstream face is increasing in volume.
The remedies for the above mentioned issues may be undertaken as per the Emergency action Plan (EAP) of the dam under the guidance of experts or experienced engineers in the field to avoid further damage to the dam structure. 4.2.2 Preventive Maintenance This can be further classified as Condition based Maintenance and Routine Maintenance. 4.2.2.1 Condition Based Maintenance The following maintenance should be completed as soon as possible after the defective condition is noted. These include but are not limited to: Remove all vegetation and bushes from the dam especially in earthern portion and restoring any eroded areas and to establish a good grass cover. Fill animal burrows if any Restore and reseed eroded areas and gullies on embankment. Repair of defective gates, valves, and other hydro-mechanical equipment. Repair any concrete or metal components that have deteriorated. Cleaning of the choked drainage holes in the dam body/ foundations in masonry dams.
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Repair any damages on spillway glacis, piers, energy dissipaters, training/divide walls, downstream areas etc. Repairs on the upstream face of masonry dams, in case the pointing is damaged, due to which there is increased seepage. Controlling any heavy seepage in the foundation/ inspection galleries in Masonry dams from drainage holes. Repairs of any cracks/cavities/joints in concrete/masonry dams/structures. However many of these works will require the services of experienced engineers/expert panels. 4.2.2.2 Routine Maintenance Several tasks should be performed on a continuous basis. These include but are not limited to the following: Routine mowing, restore and reseed eroded areas and gullies on downstream face of the left flank embankment and general maintenance including repairs/cleaning of surface drains on downstream face and in the downstream area. Maintenance and treatment of any cracks/joints/ cavities in Concrete/Masonry dams and spillways based on the recommendations of experienced engineers / expert panels. Observation of any springs or seepage areas, comparing quantity and quality (clarity) with prior observations in the embankment. Monitoring of downstream development which could have an impact on the dam and its hazard category. Maintenance of Electrical & Hydro-Mechanical equipment and systems e. g. Servicing of spillway gates & stop logs, hoisting arrangements, gates/hoist of outlet works/sluices & stand by generator. Maintaining proper lighting at dam top, galleries, etc. Monitoring of seepage in galleries. Monitoring/ cleaning & removal of leached deposits in porous concrete / formed drains in dam body and foundation drainage holes. Maintenance of all dam roads & access roads.
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Operation of electrical and mechanical equipment and systems including exercising gates and valves. To keep the gate slots clear of silt/debris. Testing of communication systems Maintenance / testing of monitoring equipment and safety alarms. Testing of security equipment 4.3Maintenance Items The O&M Manual includes detailed instructions and schedules for performing periodic maintenance works at the site. This includes maintenance of the dam, the appurtenant works, and the reservoir areas. Methodology / Specifications for carrying out maintenance works of general & recurring nature should be included in the Manual. Dam repairs are scheduled based on severity of the problem, available resources, and weather conditions. For example, if a severe settlement problem (more than envisaged in designs) or cracking is detected on the crest of the dam, it should have a high priority since further degradation could lead to dam breaching. The causes of all major issues / problems should be identified and evaluated by experienced engineers/ Expert Panels so that appropriate remedial measures can be finalized. Correcting minor rill erosion on the downstream slope could be assigned a low priority since it is not a dam safety concern. This type of repair will also be weather dependent, since grass can only be planted during specific times of the year, and the embankment should be dry so that more damage is not inflicted to the embankment slopes. 4.3.1 Earthwork The surfaces of an earthen dam may deteriorate due to several reasons. For example, wave action may cut into the upstream slope, vehicles may cause ruts in the crest or slopes, trails left by livestock can result in erosion, or runoff waters may leave erosion gullies on the downstream slope. Other special problems, such as shrinkage cracks or rodent damage, may also occur. Damage of this nature must be repaired constantly. The maintenance procedures described here are effective in repairing minor earthwork problems. However, this section is not intended to be a technical guide, and the methods discussed should not be used to solve serious problems. Conditions such as embankment slides, structural cracking, and sinkholes threaten the
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immediate safety of a dam and require immediate repair under the directions of experienced engineers/Expert panels. The material selected for repairing embankments should be free from vegetation, organic materials, trash, and large rocks. If flow-resistant portions such as the core of an embankment dam are being repaired, materials that are high in clay or silt content should be used. If the area is to be free draining or highly permeable (such as pervious shell of an embankment dam) the material should have a higher percentage of sand and gravel. It is usually satisfactory to replace or repair damaged areas with soils like those originally in place. An important soil property affecting compaction is moisture content. Soils that are too dry or too wet do not compact well. One may test repair material by squeezing it into a tight ball. If the sample keeps its shape without cracking and falling apart (which means it is too dry), and without depositing excess water onto the hand (which means it is too wet), the moisture content is near the proper level. Before placement of earth, the repair area needs to be prepared by removing all inappropriate material. All vegetation, such as bushes, roots, and tree stumps, along with any large rocks or trash need to be removed. Also, unsuitable earth, such as organic or loose soils, should be removed, so that the work surface consists of exposed, firm, clean embankment material. Following cleanup, shape and dress the affected area so that the new fill can be placed and compacted in horizontal lifts to the level specified in the technical specifications. Also it must be properly keyed (benched) with the existing material for which proper construction practices ae carried out to “knit” the new fill in to the existing soils to ensure proper bonding. This can be accomplished by using the following simple procedures 1. Scarify the existing soil layer 2. Place new moisturized soils in loose layers up to 20 centimeters thick 3. Compact to required density at optimum moisture content (OMC) 4. Scarify compacted layer 10 centimeters 5. Moisturize the layer before placement of soils 6. Compact 7. Continue process until lines and grades are accomplished. Overbuild can be trimmed back
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to design lines and grades 8. Seed of turf the fill to minimize erosion processes 9. Water routinely to ensure turf root system is fully developed. Erosion is one of the most common maintenance problems at embankment structures. Erosion is a natural process and its continuous forces will eventually wear down almost any surface or structure. Periodic and prompt maintenance is essential to prevent continuous deterioration and possible failure. Turfing, free from weeds and deleterious materials, is an effective means of preventing erosion. Rills and gullies should be filled with suitable soil, compacted, and then seeded or turfed as necessary. Large eroded gullies can be slowed by stacking bales of hay or straw across the gully until permanent repairs can be made. Erosion is also common at the point where an embankment and the concrete walls of a spillwayor other structure meet. Poor compaction adjacent to such walls during construction and later settlement can result in an area along the wall that is lower than the grade of the embankment. People often walk along these walls, wearing down the vegetative cover. Workable solutions include re-grading the area so that it slopes away from the wall, adding more resistant surface protection, or constructing steps. Steps can be provided / constructed at regular intervals along the length of the dam for going from downstream toe to the dam top. All vehicular traffic, except for maintenance, should be restricted from the dam. Paths due to pedestrian, livestock, or vehicular traffic (two and four-wheeled) are a problem on many embankments. If a path has become established, vegetation will not provide adequate protection and more durable cover will be required unless traffic is eliminated. Stones may be used effectively to cover such footpaths. Runoff often concentrates along embankment slopes where the hinge point on the crest is lower than the surrounding crest and runoff ponds in these low areas. The concentrated runoff flows downs the slope cutting the soils and forming rills and gullies resulting in loss of design lines and grades and affecting stability of the structure.
4.3.2 Upstream Riprap The upstream face is protected against wave erosion. Rip-rap is provided for the purpose with filter layers below. Nonetheless, erosion can still occur in existing riprap. Water running
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down the slope under the riprap can erode the finer filter materials under the riprap and soils leaving voids and loss of grade. Wave runup will also undermine the filter layer especially along the full reservoir level and over time wash out finer material. This can be checked through observance of linear embankment settlement. Sections of riprap that have slumped downward are often signs of this kind of erosion. When erosion occurs on the upstream slope of a dam, repairs should be made as soon as possible. Repairs can be made following the same design details asprovided in the embankment section. proper preparation of the surfaces of the existing embankment as described in the earlier paragraph for placement and compaction of embankment. Please refer to IS 8237- Code of practice for protection of Slopes for Reservoir Embankments is recommended to be reviewed and followed for carrying out this repair work
4.3.3 Controlling Vegetation Keep the entire dam clear of unwanted vegetation such as bushes or trees. Excessive growth may cause several problems: It can obscure the surface of an embankment and not allow proper inspection of the dam. Large trees can be uprooted by high wind or erosion and leave large voids that can lead to breaching of the dam. Some root systems can decay and rot, creating passageways for water, leading to piping erosion. Growing root systems can lift concrete slabs or structures. Rodent habitats can develop undetected. All bushes/trees should be as far as possible removed by root to prevent regrowth. The resulting voids must be backfilled with suitable, well-compacted soils. It is recommended to remove the plants/vegetation at their early stage to prevent or minimize their growing into big trees/bushes, etc. In cases where trees and bushes cannot be removed, the root systems should be treated with environmentally-friendly herbicides (properly selected and applied) to retard further
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growth. Concerned Government Agencies must be consulted for selection of appropriate herbicides & their use for control of vegetation on dam structures or any water bodies.
4.3.4 Controlling Animal Damage Livestock are not allowed to graze on the embankment section of the dam. When soil is wet, livestock can damage vegetation and disrupt the uniformity of the surface. Moreover, livestock tend to walk in established paths and thus can promote erosion. The burrows and tunnels of burrowing animals (beaver, muskrat, groundhogs and others) weaken earthen embankments and serve as pathways for seepage from the reservoir. Large burrows found on the embankment should be filled by mud packing. This method involves placing vent pipe in a vertical position over the entrance of the den. Making sure that the pipe connection to the den does not leak, the mud-pack mixture is poured into the pipe until the burrow and pipe are filled with the soil-water mixture. The pipe is removed and more dry earth is tamped into the entrance. As per some US publications, the mud pack is generally made by adding water to 90% earth & 10% cement mixture until slurry or thin cement consistency is attained. For bigger holes, bentonite coated stones can also be used. All entrances should be plugged with well-compacted earth and grassy vegetation re-established. Dens should be eliminated without delay. Different repair measures will be necessary if a dam has been damaged by extensive small or large rodent tunneling activity. The area around the entrance can be excavated and then backfilled with impervious material. This will plug the passage entrance to prevent water entry and saturation of the embankment.
4.3.5 Controlling Ants and Termites (White Ants) Ants and termites have become one of the most serious pests for Embankment dams. They both need water to survive and have been found on most of the embankment dams in India. These insects can create problems in the dam itself and with any of its electrical components. In some habitats, ants and termites can move as much or more soil as earthworms, thereby reducing soil compaction. Nest galleries can penetrate in a V-shaped pattern below the nest,
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penetrating as much as more than one meter deep in the soil. These galleries can create pathways for surface water to penetrate in the dam, resulting in internal erosion and collapse of the surface. Ants and termites left undisturbed can build mounds that can become quite large. These can create problems for mowing. However, frequent mowing can induce the colonies to migrate to neighboring, undisturbed areas. There are many options for managing ants and termites. Use only pesticides labeled as suitable for the location you want to treat. Make every effort to avoid contaminating water with pesticides and ensure. 4.3.6 Controlling Damage from Vehicular Traffic As mentioned earlier, vehicles driving across an embankment dam can create ruts in the crest if it is not surfaced with roadway material and sometimes even when sealed with flexible pavement, especially when the embankment is saturated and overweight trucks use theroad. The ruts can then collect water and cause saturation and softening of the dam. Other ruts may be formed by tractors or other off-road vehicles such as motorbikes are allowed to drive up and down the embankment face; these can direct runoff resulting in severe erosion. Vehicles, except for maintenance, are restricted on the dam top and kept out by fences or barricades. Any ruts should be repaired as soon as possible. 4.3.7 Masonry / Concrete Dams & Spillways
Various issues/problems that may require maintenance/ repairs on the Concrete/Masonry Dam and Spillway include but not limited to: Damages on spillway glacis, spillway piers, training/divide walls, energy dissipaters, downstream areas (probable causes are cavitation, abrasion, un-symmetrical flows, unfavorable downstream conditions) Vegetation growth in unattended areas such as spillway, spillway channel, etc. Seepage in the galleries and on the downstream face of the dam. Cleaning and removal of leached deposits from choked porous and foundation drains. Repair to upstream face of masonry dams in case the pointing is damaged, leading to increased seepage. Ensuring safe access to and within the gallery, lighting is also required as well as all outside areas during the evening hours.
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Ensuring the dam is behaving as designed based on instrumentation programs. Periodic maintenance should be performed of all concrete surfaces which are approachable to repair deteriorated areas.
4.3.8 Outlet works Outlet conduits should be inspected thoroughly once a year. Circular conduits that are one and a half meter or more in diameter can be entered and visually inspected. Common problems are improper alignment (sagging), separation and displacement at joints, cracks, leaks, surface wear, loss of protective coatings, corrosion, and blockage. Problems with conduits occur most often at the joints. Further collars at joints used to also lead to inadequate compaction. Hence, special attention should be given to them during the inspection. The joints should be checked for gaps caused by elongation or settlement and loss of joint-filler material. Open joints can permit erosion of embankment material or cause leakage of water into the embankment during pressure flow. The outlet should be checked for signs of water seeping along the exterior surface of the pipe. A depression in the soil surface over the pipe may be a sign that soil is being removed from around the pipe.
Listed below are common concerns regarding repairs to outlet works:
● Asphalt mastic is not recommended for other than temporary repairs. Asphalt mastic used as joint filler becomes hard and brittle, is easily eroded, and as per literature survey it may provide a satisfactory seal for only about five years. Mastic should not be used if the conduit is expected to flow under pressure. ● The instructions on the label should be followed when using thermosetting plastics (epoxy). Most of these products must be applied to a clean and dry surface to set up an effective bond. However cementations materials are to be preferred in view of their UV resistance & longer life. ● Material used as joint filler should be impervious to water and should be flexible throughout the range of expected air and water temperatures.
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● The internal surfaces of the conduit should be made as smooth as possible when repairs are made so that high-velocity flow will not damage the repair material. ● Minor cracks in concrete are not considered a dangerous problem. Repair is not necessary unless the cracks widen or leak. The general practice now is not to go in for pre-cast concrete/MS pipe conduits with collars but to construct RCC conduits at site without any collars and joints. PVC water stops are provided at joints and the exterior collars but to construct RCC conduits at site without any collars and joints. PVC water stops are provided at joints and the exterior faces of the conduits are given a slope to enable better contact at the interface with earth.
4.3.9 Trash racks Trash racks is provide in the u/s in front of penstock pipes. If it becomes clogged with debris or trash reduce their discharging capacity. The head losses through clogged trash racks also increase. Maintenance of trash racks includes periodic inspections for rusted and broken sections and repairs are made as needed. 4.3.10 Gates and hoisting equipment The safe and satisfactory operation of Malankara Dam depends on proper operation of its Gates & Hoisting Equipment. Maintaining spillway gates in working condition is critical for dam safety and is to be assigned the highest priority. If routine inspection of the Hydro- Mechanical Equipment shows the need for maintenance, the work should be completed as soon as possible. The simplest procedure to ensure smooth operation of gates is to operate them through their full range at least once, and preferably twice annually (before monsoon & after monsoon keeping a gap of at least six months). Because operating gates under full reservoir pressure can result in large discharges, exercising of gates should preferably be carried out during dry conditions or lean times of the year using the stop-logs/ emergency gates.
4.3.10.1 Vertical lift fixed wheel and slide gates.
Commonly used Gates and Hoists including their inspection / maintenance requirements are discussed below. 57
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The aspects to be inspected and maintained periodically for ensuring proper operation of these gates are as under: i) The gate slot and bottom platform/sill beam should be cleaned periodically. Scales formed over the embedded parts should be removed. Second-stage concrete should be checked for any development of cracks / leakages and repairs should be attended to immediately. ii) The gate leaf should be thoroughly cleaned and repainted as and when necessary according to the procedure or guidelines- indicated in IS: 14177 or as per the recommendations of the paint manufacturer. All drain holes provided in the gate assembly should be cleaned. iii) Rubber seals should be smoothed, if required, for proper alignment. All nuts and bolts fixing the seal to the gate should be tightened uniformly to required torques. Seals, if found damaged or found leaking excessively should be adjusted, repaired or replaced as considered necessary. iv) The wheel shall be rotated to check their free movement. Gate roller bearings and guide roller bushes should be properly lubricated. Whenever necessary these should be openedfor rectifications of defects, cleaning and lubrication and should thereafter be refitted. Thesemay be replaced if repairs are not possible. v) Hoisting connection of the gate leaf should be lubricated where necessary and defects if any should be rectified. vi) All nuts, bolts, check nuts and cotter pins of the lifting devices should be checked periodically. vii) All components should be greased and lubricated. Recommended and approved oils and grease only should be used. viii) Roller assembly should be adjusted by the eccentricity arrangement to ensure all rollers rest uniformly on the track plates particularly in the closed position of the gate. ix) Where filling valves are provided as part of the gate structure, all the nuts, bolts, check nuts etc. should be tightened. x) All welds shall be checked for cracks/ damages. Any weld that might have become defective should be chipped out and redone following the relevant codal provisions. Damagednuts, bolts, rivets, screws etc. should be replaced without delay.
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xi) The filling-in valves allow passage of water when it is lifted by lifting beam & crane due to creation of space between stem seat and exit passage liner. The springs and associated components should be checked periodically for damages and replaced if necessary. xii) The guide-assemblies, wheel-assemblies and sealing-assemblies shall be cleared off grit, sand or any other foreign material. xiii) The wheel pin shall be coated with corrosion resistant compound. xiv) All nuts and bolts shall be tightened.
4.3.10.2 Radial Gates. The aspects to be inspected and maintained periodically for ensuring proper operation of these gates are as under : a) Rubber Seals: i) Seals shall be inspected for leakages. Locations of excessive leakages shall be recorded for taking remedial measures. Weeping or slight flow in localized area will not require immediate remedial measures. However, measures like tightening of bolts are carried out. Further adjustment is carried out during annual maintenance. ii) If leakage is excessive & immediate repair is considered necessary, the stop log gates shall be dropped and seals repaired or replaced. NOTE: - During monsoon period, stop log gates shall NEVER be lowered in spite of heavy leakage through seals. b) Trunnion block assembly and anchorages: (i) All the nuts and bolts of Trunnion block assembly and its anchorages shall be checked for tightness. (ii) Check all the welds for soundness and rectify defects. (iii) Check whether the Yoke girder and thrust block is covered on not. If not, cover it with mild steel plates. (iv) Cover the trunnion pin with anti- corrosive jelly. (v) Remove all dirt, grit etc. from trunnion assembly and lubricate trunnion bearings of the gate with suitable water resisting grease as recommended by bearing manufacturers.
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c) Gate structures: i) Check all the welds for soundness and rectify defects. ii) Check welds between arms and horizontal girders as well as between latching bracket and skin plate with the help of magnifying glass for cracks/defects and rectify the defects. iii) Clean all drain holes including those in end arms and horizontal girders. iv) Check all the nuts and bolts and tighten them. Replace damaged ones. v) Check upstream face of skin plate for pitting, scaling and corrosion. Scaling may be filled with weld and grinded. Corroded surface shall be cleaned and painted. d) Embedded Parts: i) All the sill beams and wall plates shall be inspected for crack, pitting etc. and defects shall be rectified. ii) The guide roller pins shall be lubricated. e) General Maintenance: i) Defective welding should be chipped out and it should be re-welded duly following the relevant codal provision (IS: 10096, Part-3). ii) Damaged nuts, bolts, rivets, screws etc. should be replaced. iii) Any pitting should be filled up by welding and finished by grinding if necessary. iv) The gate leaf, exposed embedded metal parts, hoists and hoist supporting structure etc., should be thoroughly cleaned and repainted when required keeping in view the original painting system adopted and as per the guidelines contained in IS: 14177. v) Trunnion bearing should be greased as and when required. Keeping trunnion bearings in perfect working condition is very important. All other bolted connections should also be checked up for proper tightness. vi) Bolts and trunnion bearing housing should be tightened wherever required. vii) The seals of the gate should be checked for wear and tear and deterioration. These should be adjusted/replaced as and when necessary. viii) The wall plates, sill beams shall be checked and repaired if necessary. ix) Wire ropes should be properly lubricated.
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x) Oil level in the worm reduction unit should be maintained by suitable replenishment. Oil seals should also be replaced if required. Lubrication of other parts of hoists such as chains, position indicators and limit switches should also be done. xi) The stroke of the brake should be reset to compensate for lining wear. Worn out brake linings should be replaced in time. xii) Flexible couplings should be adjusted if required. xiii) Repairs and replacements of all electrical relays and controls should be attended to. xiv) Maintenance of alternative sources of Power such as Diesel Generating sets and alternative drives wherever provided should be carried out. xv) The list of essential spare parts to be kept available should be reviewed and updated periodically. The condition of spares should be checked periodically and protective coating given for use.
4.3.10.3 Electrically operated fixed hoists 1. General Instructions: a) Operation of fixed hoist without lifting the gate is not possible and need not therefore be attempted. It will be possible to operate the unit and observe operation of load carrying hoist component when gate is being lifted or lowered. b) Never open any bolt or nut on motor, gear boxes, rope drums and other load carrying hoist components when the gate is in raised position. The gate should be fully closed or rested on the gate latches before carrying out any work on hoist components including motor brake and other electrical equipment. c) The aspects to be inspected and maintained periodically for ensuring proper operation of Rope drum hoists are as under; i. Entrance to all hoist platforms shall be kept locked. All keys shall remain with the shift supervisor. ii. A cursory daily inspection shall be made of hoist and gate to ensure that there is no unusual happening. iii. Clean all hoisting equipment and hoist platform. iv. Check oil level in gearboxes and replenish as and when required with oil of
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proper grade. v. Apply grease of suitable grade by grease gun. vi. Lubricate all bearings, bushings, pins, linkages etc. vii. Check all the fuses on the power lines. viii. All bolts and nuts on gear boxes, hoist drum and shaft couplings should be checked for tightness. ix. Check the supply voltage. x. Drain sample gear oil from each of the gear boxes. If excessive foreign particles or sludge is found, the gear box shall be drained, flushed and filled with new oil. xi. All the geared couplings shall be greased. xiii. Raise and lower the gate by hoist motor and check for smooth, and trouble free operation of gate without excessive vibration. xiv. Observe current drawn by motor at the time of lifting and check if it is more than normal. If so, stop the hoist and investigate the cause and rectify. xv. Check the condition of painting of various components and remove rust wherever noticed and repaint the portion after proper cleaning as per painting schedule. xvi. All trash, sediments and any other foreign material shall be cleared off the lifting rope and lifting attachment. xvii. All ropes shall be checked for wear and tear and if broken wires are noticed, the rope shall be replaced. xviii. All the wire ropes shall be checked and all visible oxidation shall be removed. xix. All wire ropes shall be greased with cardium compound. xx. Check the overload relays for proper functioning. xxi. Check all the nuts, bolts, rivets, welds and structural components for hoisting platform and its supporting structure for wear, tear and damage. All damages shall be rectified. All bolts shall be tightened. The portion with damaged painting shall be touched up. xxii. Check the pulleys, sheaves and turn-buckles. xxiii. Raise and lower the gate for its full lift several time (at least three to four) and observe the following: a) Check the limit switches and adjust for design limits.
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b) The effectiveness and slip of the breaks shall be checked by stopping the gate in raising and lowering operations. The brakes shall be adjusted if needed. c) When the gate is operated, there should not be any noise or chatter in the gears. xxiv. Adjust the rope tension of wires if unequal. xxv. Check for all gears and pinions for uneven wear and adjust for proper contact. Grease the gears. xxvi. Repaint the hoist components, hoisting platform and its supporting structures as per requirement. xxvii. The periodic maintenance of commercial equipment like motors, brakes, thrusts etc. shall be carried out as per manufacturers operation and maintenance manual 4.3.10.3.1 Maintenance of Electrical components of Fixed Rope Drum Hoists: a). The electrical components to be inspected and maintained periodically are as under; i) Starters should be cleaned free of moisture and dust. ii) Each individual contactor should be tried by hand to make sure that it operates freely. iii) All wearing parts should be examined in order to take note of any wear which may have occurred during operation. iv) If the contactor hums, the contact faces should be cleaned. (v) Examine all connections to see that no wires are broken and no connections are loose. vi) Clean the surface of the moving armature and magnet core which comes together when the contactor closes, free of dust or grease of any kind. vii) Examine the mechanical interlocks between the reversing contactor and see when the contact tips of one of the contactor units are touching, it is impossible to get the contact tips of the other unit to touch. viii) The contact tips should be kept free from burns or pits by smoothening with fine sand paper or emery paper. ix) Replace the contact tips which have worn away half-way. x) Do not lubricate the contacts. xi) Blow out windings thoroughly by clean and dry air to clear air passage in the stator and the rotor of any accumulated dirt. The air pressure shall not be too high to damage the insulation.
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xii) Examine earth connections and motor leads. xiii) Examine motor windings for overheating xiv) Examine control equipment’s xv) Examine starting equipment for burnt contacts xvi) Check and tighten all nuts and bolts xvii) Clean and tighten all terminals and screw connections all contact surfaces shall be made clean and smooth. xviii) Lubricate the bearings xix) Overhaul the controllers xx) Inspect and clean circuit breakers. xxi) Wipe brush holders and check bedding of brushes. xxii) Blow out windings thoroughly by clean and dry air. The pressure shall not be so high that insulation may get damaged. xxiii) Check the insulation resistance of the motor between any terminal and the frame. If the measured resistance is less than the prescribed value, then steps shall be taken to dry- out the motors either by passing a low voltage current through the windings or by placing the stator and rotor only in a warm dry place for a day or so. WARNING: The complete motor shall never be put in an oven for drying as that may melt the grease out of bearings. xxiv) Coat the windings with an approved high temperature resisting insulation enamel or varnish. xxv) Over haul the motor, if required. xxvi) Check the switch fuse units and renew, if required. xxvii) Check resistance or earth connections. xxviii) Check air gap. b) Solenoid Operated Brakes i) All fixing bolts shall be checked and tightened at least once in three months. ii) The magnet stroke should be reset to compensate for wear. iii) Re-adjust the brake when the magnet stroke reaches the value given on the instruction plate.
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iv) Brake lining should be checked and replaced when required. v) Examine all electrical leads and connections. vi) Rubber bushes or couplings should be checked and replaced if defective. vii) The pins should be tightened. viii) Brake drum shall be cleaned to remove any dust or grease. Stop logs, lifting beam & gantry crane
A. MAINTENANCE OF SPILLWAY RADIAL GATES a. Regular Maintenance 1. For gear and pinion, grease or lubricating compound shall be frequently used for the smooth operation 2. Wire Rope should be kept lubricated on regular basis with cadmium compound. 3. Damaged nuts, bolts etc. should be replaced 4. Oil level in the gear box and worm reducer should maintained. 5. Electromagnetic brake should be checked regularly and plunger to be cleaned dry to ensure proper functioning. The break shop to be cleaned. b. Periodical Maintenance 1. Wire Rope should be examined for rusting, broken strands etc. and the wire rope at both the ends of the gate should have equal initial tension. 2. All nuts, bolts and screws shall be checked for wear, tear and tightness 3. Drain oil from gear box once in every 6 months and replace with relevant grade. 4. Ensure proper meshing of gear and pinion. 5. Location and adjustment of guide shoe should be checked. 6. Check E.M. Brake and thruster brake properly functioning. 7. All the moving parts should be properly lubricated. 8. The fuses are to be checked and replaced when they are worn-out. Replacements of fuses are necessary when they emit smell or get over heated. Care should be taken to select the correct size of fuses.
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B. MAINTENANCE OF MOTOR Motors shall be blown out at regularly intervals to keep its ventilating passage clear, particularly when operating in dirty atmosphere. Moisture, oil, dirt, grease and carbon or metallic dust are the principal causes of break down. The motor therefore be kept clean and dry and must be kept free from oil and greases, damp and dirt, periodical cleaning with dry compressed air with a brush is necessary. The motor required be examining and dismantling from time to time and frequency of service cleaning will depend upon the conditions under which the motor operates. During periodical cleaning care shall be taken to clean air passage in the starter and motor of any accumulated dirt. Terminals and screw connections shall be kept clean and tight. If they become dirty or corroded, they shall be disconnected and all contact surfaces made clean and smooth. Bad contact leads to sparking and ultimate breakdown. C. LUBRICATION AND MAINTENANCE OF REDUCTION GEAR UNIT 1. Satisfactory performance of grease required that the lubricating oil kept be clean, and free from dirt, grit, moisture and sludge. Depending upon operating conditions the oil eventually becomes contaminated and should be drained periodically. During operation the oil level should be periodically checked, too high level results loss of power and oil leakage, too low oil results in friction in bearings and on gear teeth causing overheating. Use proper graded oil. 2. Oil level should be checked with the help of dipstick or the oil indicator and should be topped up, if necessary. 3. Where the bearings of the unit are greases lubricated, the same should be filled with the top of grease gun. 4. Care should be taken that the breather holes are not clogged by any foreign materials, like dust, paint etc. 5. During cleaning gear casing should be flushed with the same sort oil that is used under working Conditions. If encasing is opened for cleaning all sealing compound must be removed.
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Table 4. 1. LUBRICATION CHART
Sl PART LUBRICATION FOR FREQUENCY no. 1 Hoist Brake Fulcrum pins Hand oiled points One in a month
2 Long travel Brake fulcrum Hand oiled points One in a month pins
3 Motors: Hoist Long travel End Bearing Replace once in six Months and renew Once in a year.
4 .Long travel Shaft Plummer Grease Nipples Repack once in Six Months Blocks and renew Once in a year .
5 Gear Boxes Gear Boxes Check oil level once A month and top up As necessary.
6 Pinion & Gear wheels Gears & Pinions Every 3 Months 7 Wire Rope Full wire (Cardium Every year preferably before compound) onset of Monsoon
F. MAINTENANCE OF BEARING Like all other important machine components ball and roller bearings must occasionally be cleaned and examined. In many cases it is permissible to let the bearing run for considerable / longer time before carrying out inspections, especially the conditions of the bearings can be ascertained, during service for example, by listening to the sound produced during running, checking the temperature of noting the colour of the lubricant. While spirit good quality paraffin, petrol or benzene may be recommended as suitable for cleaning roller bearings.
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Bearing should not be allowed to stand dry for any length of time after they have cleaned out, should be oiled and greased immediately when this is done, the bearings should be rotated several times to that oil or grease can reach all vital parts and thereby protect the bearings from rust. For sheaves, oiling the bearing at frequent interval and checking that they rotate freely must be done. A seized up sheaves may ruin a rope very speedily. Care should be taken to see that the rope does not foul in flat against any obstacle in its way.
G. MAINTENANCE OF WIRE ROPE Frequently the inspection of the entire length of rope is necessary. Watch constantly for broken wires, excessive wear and lubrication, see that the number of broken wires does not exceed as laid down in different regulation. Prompt attention must be given to a broken wire in a rope otherwise damage to other wires and serious accidents may results. Cleaning wire rope with brush or compressed air and giving it a light coating of special wire rope dressing is essential. This lubricant puts a protective film on each individual wire, repels water and stops corrosion. H. CHECK FOR THE TIGHTNESS OF THE BOLTS 1. Fixing bolts of motor and reduction gears. 2. Plummer Block base Bolts. 3. Bolts of all Coupling. 4. Inspect the keys in the Couplings for its correct position once in every six months. 5. The wire Rope and is fixed over the winding drum by weans of clamps and bolts. These are to be checked for its tightness periodically. ADDITIONAL MAINTENANCE ITEMS FOR RADIAL GATES The following aspects are to be considered and attended to during maintenance: 1. Defective / damaged / cracked welding should be cutout and re-welded. 2. Damaged nuts, bolts, screws etc. should be replaced. 3. The gate leaf should be thoroughly cleaned and repainted whenever necessary
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4. Rubber seals should be ground, if required to bring it in to alignment. All nuts and bolts for fixing seals to gate should be tightened uniformly. Seals when damaged or found leaking excessively should be adjusted or replaced as and when considered necessary. 5. All components should be greased and lubricated with the recommended oil and grease only. 6. The roller assembly should be adjusted by the eccentricity provision to ensure that all the rollers rest uniformly on track plates particularly in the closed position of the gate. 7. The drain holes in horizontal girders should be cleaned. 8. It should be ensured that no bearing is overheated. 9. The gate slots should be kept cleaned. The scaling over the embedded parts should be removed. Since normally the stop logs remain in hanging position, for any routine maintenance, these are required to be raised up to the top of pier or deck level to rest on the dogging beam with the help of the gantry crane and lifting beam. Thereafter, if required, it is further raised at a slow speed from safety point of view, it is to be ensured that these units do not foul or hit legs / columns of the gantry crane. Thereafter, the gate can be rested on the deck level for necessary maintenance, stop log units are shifted back to their original dogged position.
MAINTENANCE OF BEARING Like all other important machine components ball and roller bearings must occasionally be cleaned and examined. In many cases it is permissible to let the bearing run for considerable / longer time before carrying out inspections, especially the conditions of the bearings can be ascertained, during service for example, by listening to the sound produced during running, checking the temperature of noting the colour of the lubricant. While spirit good quality paraffin, petrol or benzene may be recommended as suitable for cleaning roller bearings. Bearing should not be allowed to stand dry for any length of time after they have cleaned out, should be oiled and greased immediately when this is done, the bearings should be rotated several times to that oil or grease can reach all vital parts and thereby protect the bearings from rust.
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For sheaves, oiling the bearing at frequent interval and checking that they rotate freely must bedone. A seized up sheaves may ruin a rope very speedily. Care should be taken to see that the ropedoes not foul in flat against any obstacle in its way.
4.3.10.4 Surface Preparation and Painting of HM Works i) Protection of painted surfaces is considered essential for protection & enhancement of service life. Gates, their embedded parts, gate leaf, hoists and its supporting structures need to be protected against corrosion due to climatic condition, weathering, biochemical reaction and abrasion etc. This equipment is likely to deteriorate or get damaged to any extent that the replacement of parts may become necessary and such replacement may become difficult and costly. ii) Surface preparation & Painting requirements: Painting for hydro-mechanical works is to be carried out as prescribed in IS 14177 for both newly manufactured as well as old & used gates, hoists and associated works after proper surface preparation. The preparation includes thorough cleaning, smoothing irregular surfaces, rusted surfaces, weld spatters, oil, grease, dirt, earlier applied damaged layers of primers/ paint by use of mechanical tools, by use of solvents, wire brush etc. The sand / grit blasting process is used for surface preparation to a level of Sa 2½ of the Swedish standard. iii) Surfaces not requiring painting & their protection during surface preparation, painting & transportation process: a) The following surfaces are not to be painted unless or otherwise specified: • Machine finished or similar surface • Surfaces which will be in contact with concrete • Stainless steel overlay surfaces. • Surfaces in sliding or rolling contact • Galvanized surfaces, brass and bronze surfaces. • Aluminum alloy surfaces b) The Surfaces of stainless steel, nickel, bronze and machined surface adjacent to metal work being cleaned or painted shall be protected by using sticky protective tape or by other suitable means over the surfaces not to be painted.
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c) All embedded parts which come in contact with concrete shall be cleaned as detailed above and given two coats of cement latex to prevent rusting during the shipment while awaiting installation. iv) Application of primer &finish coats on embedded parts and gates: a) EMBEDDED PARTS: • The prescribed primer shall be applied as soon as the surface preparation is complete and prior to the development of surface rusting and within the specified time prescribed by Indian Standards or the Paint Manufacturer. In case there is lapse of considerable time beyond the prescribed time limit, the surfaces shall be again cleaned prior to priming. • Two coats of zinc rich primer with epoxy resin shall be applied to all embedded parts surfaces which are not in contact with concrete and shall remain exposed to atmosphere or submerged in water to obtain a dry film thickness of 75 microns. • This shall be followed by three coats at an interval of 24hours of coal-tar blend epoxy resin so as to get a dry film thickness of 80 microns in each coat. Total dry film thickness of paint shall not be less than 300 microns. b) GATES: Primer Coat: • Over the prepared surface one coat of inorganic zinc silicate primer giving a dry film thickness of 70 ± 5 microns should be applied. Alternatively two coats of zinc rich primer, which should contain not less than 85% zinc on dry film should be applied to give a total dry film thickness of 75 ± 5 microns. Finished paint: • Two coats of solvent less coal tar epoxy paints. These shall be applied at an interval of about 24 hours. Each coat shall give a dry film thickness of 150±5 microns. The total dry film thickness of all the coats including primer coating shall not be less than 350 microns. v) Hoist and supporting structure: a) Structural components:
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Primer coats of zinc phosphate primer shall be applied to give a dry film thickness of 40±5 microns. Final Coats: One coat of alkalized based micaceous iron oxide paint to give a dry film thickness of 65 ± 5 microns followed by two coats of synthetic enamel paint confirming to IS 2932 – 1974 to give a dry film thickness of 25 ± 5 microns per coat. The interval between each coat shall be 24hours. The total dry thickness of all coats of paint including the primer coat shall not be less than 175 microns. b) Machinery: Except machined surfaces all surfaces of machinery including gearing, housing, shafting, bearing pedestals etc., shall be given: Primer coats: One coat of zinc phosphate primer paint to give minimum film thickness of 50 microns. Motors and other bought out items shall be painted if necessary. Finished coats: The finished paint shall consists of three coats of aluminum paint confirming to IS2339 – 1963 or synthetic enamel paint confirming to IS 2932 – 1977 to give a dry film thickness of 25±5 microns per coat to obtain a total minimum dry film thickness of 125 microns. c) Machined surfaces: All machined surfaces of ferrous metal including screw threads which will be exposed during shipment or installation shall be cleaned by suitable solvent and given a heavy uniform coating of gasoline soluble removable rust preventive compound or equivalent. Machined surfaces shall be protected with the adhesive tapes or other suitable means during the cleaning and painting operation of other components. vi) Application of paint: Mix the contents thoroughly as directed by paint manufacturer before and during use. Painting at shop can be done by any of the three methods namely Brush / roller, Conventional spray, Airless spray etc. The paint can be made to suit the adopted method. But once the gate and equipment is in erected position the general method adopted is only brush / roller. In case of spray lot of precautions are to be taken. For More details: Refer IS: 14177 Part (II) – 1971. Appendix A – Brushing of paint Appendix B – Spraying of paint
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Appendix C – Spray painting defects: Causes and remedies. Removal of old paint / rust and carrying out fresh painting: The carrying out of fresh painting is to be considered under the following conditions: • The rusting is noticed all over the surface or • Rusting is severe or Cracking and blistering has damaged the primer coat exposing the metal and is noticed all over the surface or • The paint film has eroded badly, the scrap of entire paint film to the base metal and carry out fresh painting. Note: In case of maintenance and renovation: Refer IS 14177 (Part II) – 1971 for checking and repainting. vii) Removal of old paint for repainting: Caution should be exercised while removing the old paint. The surfaces shall be de-rusted and descaled by either mechanically by one or more of the methods, namely: a) Wire brushing, Scraping, and chipping. Sand papering or cleaning with steel wool or abrasive paper b) Power tool cleaning c) Flame cleaning d) Sand blasting or shot blasting and e) Chemical rust removal. Note: The method of application shall be decided based on conditions existing. After cleaning painting is to be carried out as originally proposed. Some are painted without removal of old paint and rusting this will amounts to no painting and deteriorate faster than the original one. viii) Inspection and testing of painting of H. M works: a) The following steps are involved in inspection of painting: General inspection before and during painting Viscosity test of paints Paint thickness test – using Elco-meter. Inspection of general appearance of finished work.
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b) General: The aim of inspection and testing is to ascertain whether the recommended practice is being employed correctly during every stage of application and whether the final results fulfill the object of painting. Any test carried out should be of non – destructive nature or, if it is of destructive nature, it should be either restricted to areas which can be restored without marring the general appearances or be such that it is possible to restore easily without necessitating a complete repetition of the work. c) Inspection of surfaces prior to painting: Inspection methods will depend on whether it is to be painted for the first time or is to be repainted. d) New Works (Not previously painted): The following shall be decided by inspection: The method of pre cleaning feasible or recommended; The intermediate protective treatments to be applied, if found necessary; The final painting schedule and the specifications for the paint for ensuring the particular performance; The method of application, whether by brush, roller or spray. e) Old Work (Which requires repainting): The following shall be decided by inspection: Whether the entire existing paint requires removal; and/or Whether repainting without paint removal would be adequate. 4.3.11 Electrical System Electricity is typically used at a dam for lighting and to operate the gates, hoists, recording equipment, and other miscellaneous equipment. It is important that the Electrical system be well maintained, including a thorough check of fuses and a test of the system to ensure that all parts are properly functioning. The system should be free from moisture and dirt, and wiring should be checked for corrosion and mineral deposits. All necessary repairs should be carried out immediately and records of the works kept. Maintain generators used for auxiliary emergency power -- change the oil, check the batteries and antifreeze and make sure fuel is readily available.
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Monitoring devices usually do not need routine maintenance. Open areas are particularly susceptible to vandalism. As such all electrical fittings like bulbs, lights, loose wires etc. in open areas should be checked routinely and replaced / repaired where needed. The recommendations of the manufacturer should also be referred to.
4.3.12 Maintenance of Metal Gate Components All exposed, bare ferrous metal of an outlet installation, whether submerged or exposed to air, will tend to rust. To prevent corrosion, exposed ferrous metals must be either appropriately painted (following the paint manufacturer’s directions) or heavily greased in respect of moving parts & on surfaces like guides & track seats on which there is movement of gates. When areas are repainted, it should be ensured that paint is not applied to gate seats, wedges, or stems (where they pass through the stem guides), or on other friction surfaces where paint could cause binding. Heavy grease should be applied on friction surfaces to avoid binding. As rust is especially damaging to contact surfaces, existing rust is to be removed before periodic application of grease. 4.3.13 Access Roads For a dam to be operated and maintained, there must be a safe means of access to it at all times. Access road surfaces must be maintained to allow safe passage of automobiles and any required equipment for servicing the dam in any weather conditions. Routine observations of any cut and fill slopes along the sides of the road should be made. If unstable conditions develop assistance of experienced Engineers/Expert Panels should be obtained and remedial measures initiated. Drains are required to be provided and maintained along roads to remove surface and subsurface drainage. This will prolong the life of the road and help reduce deterioration from rutting. Road surfacing should be repaired or replaced as necessary to maintain the required traffic loadings. In most cases, specialized contractors will be required to perform this maintenance. 4.3.14 General Cleaning As already suggested, for proper operation of spillways, sluiceways, approach channels, inlet and outlet structures, stilling basin / energy dissipation arrangements, discharge conduit,
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dam slopes, trash racks, debris control devices etc., regular and thorough cleaning and removal of debris is necessary. Cleaning is especially important after large floods, which tend to send more debris into the reservoir. 4.4 Materials requirements for maintenance during Monsoon Period Materials required during monsoon period for both immediate maintenance and preventive maintenance must be stocked in adequate quantities for emergency situations that may arise. Materials required during monsoon period for both immediate maintenance and preventive maintenance must be stocked in adequate quantities for emergency situations that may arise. In Malankara dam, normally a 24x7 hour patrolling is carried out during monsoon period. The materials normally required to be stocked in sufficient quantity are: - Gunny Bags Sand Boulders/Wire crates Bamboos/Balli‘s Baskets Ropes Petromax Lamps with Spares Torches with spare cells Kerosene Oil Match Boxes Rain Coats Gum Boots Warning sign indicator Danger zone lights
4.5 Establishment requirements The requirements of annual and monsoon establishment for the operation and maintenance of a dam is to be decided by the Dam Owners on a case to case basis. A typical organization 76
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set up for dams as per its height covering supervision staff down to Assistant Engineer level as already explained in Chapter 2. In addition there will be other supporting staff (skilled/unskilled), regular/work charged staff/labours depending upon the requirements in monsoon& non-monsoon period. The following personals are required for the Annual and Monsoon establishment: Driver with vehicle- 1 No Electrician - 1 No Skilled Worker/ Lascar – 2 No Unskilled worker – 1 No 4.6 Preparation of O&M budget In order to prepare O&M budget for a dam project all possible costs associated with implementation of O&M Program need to be identified and considered. Typical O&M budget for a project should essentially include but not limited to the following items: i) Establishment Cost of Regular Staff - Salaries and allowances, Bonus, Medical Reimbursement,LTC, Leave Encashment, pension benefits, etc. (as applicable). ii) Establishment Cost of Work charged Staff - Salaries and allowances, Bonus, Medical Reimbursement, LTC, Leave Encashment, Pension benefits, TA and DA , etc. (as applicable). iii) Establishment Cost of Daily wage Staff - Salaries and allowances, TA and DA etc. (as applicable). iv)Office Expenses – Rent for office, Telephone/Mobile/any other Telecommunication bills, Electricity bills, water bills, Office stationery, Day to day office requirements. v) Motor Vehicles - Running and Maintenance cost of inspection vehicles, Cost of hiring ofvehicles as required vi)Maintenance of Colony - Maintenance of staff quarters, colony roads, Electricity, Sanitary and Water supply systems etc. vii) T&P - T&P requirements for offices, colony, works etc. as applicable. viii) Works -Painting, oiling, greasing, overhauling of HM equipment’s, Repair/replacement ofgates seals & wire ropes, POL for pumps & generator sets, Electricity charges and maintenance of Electric systems of dam site, specific requirements for all Civil, H.M & Electrical maintenance works, vegetation removal and mowing of turfing on earth dams,
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maintenance/ cleaning of drains in dam, maintenance of lift/elevators in dam (as applicable), maintenance of access roads & basic facilities, provision for flood contingency works during monsoon, unforeseen events/items (about 10% of the cost of works) etc. Table 4. 2. O&M BUDGET COSTS (ANNUAL)
PREVIO CURREN US YEAR T YEAR Sl.N BUDGET ITEM COST(Rs. BUDGET REMAR o. ) (YR)(RS. K )
A. ESTABLISHMENT
1 SALARY OF REGULAR STAFF INCLUDING ALL OTHER BENEFITS
2 TRAVEL EXPENSES
3 OFFICE EXPENSES
4 MOTOR VEHICLE EXPENSES
5 MAINTENANCE OF OFFICE & COLONY
SUB-TOTAL-A
B. WORKS
1 CIVIL
1.1 CONCRETE / MASONRY DAM
1.2 EARTHEN DAM
1.3 INTAKE / OUTLETS IN EARTHEN
1.4 SLUICES CONCRETE /
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MASONRY DAM
1.5 APPROCH / INSPECTIONROADS WITH IN DAM AREA
2 HYDRO-MECHANICAL
2.1 SPILLWAY GATES &HOISTS
2.2 SPILLWAY STOP-LOG & GANTRY CRANE
2.3 OUTLETS IN EARTHEN DAMS SERVICE / EMERGENCY GATES & HOISTS
2.4 SLUICES IN CONCRETE / MASNRY DAMS – SERVICE / EMERGENCY GATES & HOISTS
3 ELECTRICAL
3.1 ELECTRICAL FITTINGS, MOTORS, CONTROLS FOR GATE HOISTS
3.2 POWER SUPPLY LINES
3.3 ELECTRICAL FITTINGS ON DAM TOP DAM GALARIES, etc.
3.4 STANDBY POWER / DIESEAL GENERATOR
3.5 REMOTECONTROL / CC TV
4 INSTRUMENTATION
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5 MISCELLANEOUS WORKS
6 SALARY OF WORK CHARGED STAFF INCLUDING ALL BENEFITS
7 MATERIALS TO BE STORED BEFORE MONSOON
SUB-TOTTAL-B
8 CONTINGENCY (10%) ON SUB TOTAL OF A & B
9 TOOLS AND PLANTS
SUB-TOTAL-C
10 TOTAL ANNUAL COST
4.7 Maintenance Records Maintenance records are of utmost importance. A record shall be kept for all maintenance activities, both immediate and preventive maintenance works. Information that must be recorded includes, but not limited to, the following: date and time of maintenance, weather conditions, the type of maintenance, name of person or contractor performing maintenance, description of work performed, the length of time it took to complete the work with dates, equipment and materials used, and before and after photographs. The data should be recorded by the person responsible for maintenance.
General comment:
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i) Ensure that O&M manual for HM equipment should cover the following in sequence: - Description of Each gates, valves with their operating mechanism (Hoist etc.) at Both Dams - Salient Features of each gate, valves with their hoists/operation. - Operation of Each gate (precondition, lifting, lowering, other functions, operation from control panel, prepare control panel, Details of push buttons, indication lamps etc., Manual operation) - Inspection & Maintenance of Each Gate with their hoist with schedule, Inspection of paints with schedule, Maintenance for Electrical works) - List of approved / recommended lubricants for each gate / hoist with schedule - Testing of gates with hoist - Trouble shooting charts - Details & Make of bought out components - Storage of Equipment - Details of instruments under HM works / gate position sensors if any - List of spares to be available for each type of gates / hoist/ valves - All reference drawings and circuit diagram with complete list - Catalogues of procured machine parts used for gates, hoists, valves, controls etc. O&M manual shall also meet the requirement/ recommendation of manufacturer of HM equipment provided in Dams.
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CHAPTER5-INSTRUMENTATION AND MONITORING
The program must be based on prevailing geotechnical conditions at the dam, and must include consideration of the hydrologic and hydraulic factors present before and after the project is in operation. Instrumentation designed for monitoring potential deficiencies at dams must consider the threat to life and property that the dam presents. Thus, the extent and nature of the instrumentation depends not only on the complexity of the dam and the size of the reservoir, but also on the potential for threat to life and property losses downstream. Continued monitoring is important to monitor the efficacy of the remedial works carried out. The involvement of personnel with experience in the design, installation, regular monitoring and evaluation of an instrumentation system is of prime importance to the success of the program. Instruments installed at a dam can indicate occurrence of any anomalous or problematic behavior. They can show that whether the dam behavior is as per design or otherwise. Actual measurements of uplift pressure in a Gravity dam and comparison with the uplift pressure assumed in original design is an example. 5.1 General Instrument types The parameters often monitored by instruments include Movements ( horizontal, vertical, rotational and lateral) Pore pressure and uplift pressures Water level Seepage flow Water quality Temperature Crack width Seismic activity Weather and precipitation data Stress and strains
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5.2 Instrumentation at Malankara Dam The following instruments are installed at the dam and their staus is as under I. V Notches - working 5.2.1 Parameters monitored Provide here details of the parameters being measured actually i) Uplift Pressure –No instrument for measuring uplift pressure ii) Water level- Monitored hourly and entered in register iii) Seepage in the foundation gallery-Monitored daily and entered in register
5.3 Frequency of Monitoring i) Water level is monitored hourly.Seepage in the foundation gallery is Monitored daily Total seepage is measured using V-notch fitted in the foundation gallery. 5.4 Data Processing and Evaluation The steps required to process and evaluate data, whether collected manually or automatically, are the same. Instrument data should be processed and evaluated according to the procedures established by the monitoring program. Accumulation of instrument data by itself does not improve dam safety or protect the public. Monthly reports are prepared for evaluation in case of Malankara dam 5.4.1 Data Collection Data collected manually should be recorded on the data sheets prepared as part of the monitoring program. Other information or observations that may be important in evaluating the data should be noted on the data sheets. Data collection for the dam- water level is monitored on hourly 5.4.2 Data Presentation All data should be summarized in graphical form. All plots should include sufficient previous data to identify any long-term trends. Furthermore, the plots should be self-explanatory. 5.4.3 Data Interpretation Data should be reviewed for reasonableness, evidence of incorrectly functioning instruments, and transposed data. Several checks for reasonableness can be made on all data. The magnitude of data should be near the range of previous data. Data that are significantly
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different may be incorrect. All data will have scatter from instrument error, human error, and from changes in natural phenomena such as temperature, wind, and humidity. The true accuracy of data will not be apparent until a significant number of readings have been taken under a variety of conditions. All data will follow trends, such as decreasing with time or depth, increasing with time or depth, seasonal fluctuation, direct variation with reservoir or tail water level, direct variation with temperature, or a combination of such trends. Interpretation of data is carried out as per standard practice & on monthly / six monthly/ yearly basis or as decided by design authorities for this dam. Interpretation of data, so collected, needs to be carried out judiciously. Help of experience personnel from the concerned field from institutes / manufacturers / instrument suppliers could prove to be useful. 5.4.4 Dam Performance Evaluation The purpose of instrumentation and monitoring is to maintain and improve dam safety. The data should be used to evaluate whether the dam is performing as expected and whether it provides a warning of developing conditions that could endanger the safety of the dam. All data should be compared with expected behaviour based on the basic engineering concepts. Variations from expected behaviour may suggest development of conditions that should be evaluated. All data should be compared with design assumptions., If no unusual behaviour or evidence of problems is detected, the data should be filed for future reference, If data deviates from expected behaviour or design assumptions, action should be taken. The action to be taken depends on the nature of the problem, and should be determined on case-by-case basis. Possible actions include. Performing detailed visual inspection. Repeating measurements to confirm behaviour. Re-evaluating stability using new data Increasing frequency of measurements. Installing additional instrumentation. Designing and construction remedial measures. Operating the reservoir at a lower level. Emergency lowering of the reservoir.
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5.4.5 Methods of Behavior Prediction Each dam is a unique structure and has its own special conditions of siting, design, construction and operation. Rigorous methods of prediction have been developed over the years. These methods apply the laws of physics to problems of slope stability, Foundation stability and rock deformation. Modern solutions use finite element ore finite difference models urn on computers. Such numerical analyses are expensive and for that reason are generally used only for larger dams. Special analyses are made when investigations reveal weak materials or other anomalies. 5.5 Visual Observations Observations by on site personnel (dam owners / operators and maintenance personnel) may be the most important and effective means of monitoring the performance of a dam. An inspector, upon each visit to the dam site, should examine it visually -walking along the dam alignment and looking for any signs of distress or unusual conditions. Table 5. 1 Instrumentation proposed in Malankara dam
Sl.no Type of Instrument Nos
1 Automatic water level sensor 1
2 Automatic rain gauge 1 3 Standard rain gauge 1 4 Thermometers 3
5 Tiltmeters 2 6 12 Joint meters
7 Uplift gauge 31 8 V notches 5
9 Settlement plates/Survey markers 15 10 Data centre at dam site – data logger etc with 1 monitoring software
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CHAPTER 6 –PREVIOUS REHABILITATION REPORTS
Before DRIP, maintenance activities were limited to routine greasing, oiling and patch painting of hydro mechanical devices routine repairof electrical systems, gallery drainage, routine mowing, vegetation removal etc. Apart from these routine maintenance activities no major rehabilitation was carried before the involvement of DRIP. Under DRIP major Rehabilitation Works have been carried out at total cost of about INR 9.1 crores. The rehabilitation works under DRIP include: Table 6. 1. Details of DRIP works
Original Revised Costs (INR) Contract Agreement Name of Work Amount amount (in crores) (in crores) 1) DRIP-Rehabilitation and Improvements of 5.65 6.28 Basic facilities of Muvattupuzha Valley Irrigation Project - Malankara Dam 2) DRIP-Rehabilitation and Improvements of 2.66 2.69 Basic facilities of Muvattupuzha Valley Irrigation Project – Construction of rivertraining wall at left side downstream of Malankara Dam 3) DRIP- MVIP- Rehabilitation and 0.8324 Improvements to the Electrical Installation of Malankara Dam 4) DRIP-Rehabilitation and Improvements of 0.8292 Ongoing Basic facilities of Muvattupuzha Valley Irrigation Project- Construction of comfort station, jet washing of dam, providing hand rails at river training wall, Improvements of Perumattom to Dam
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Other nonstructural measures under DRIP include preparation of inundation maps and Emergency Action Plan(EAP). The photographs showing rehabilitation of Malankara dam is shown below: - BEFORE
AFTER
Figure 6. 1. OFFICE BUILDING
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BEFORE
AFTER
Figure 6. 2.FENCING
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BEFORE
AFTER
Figure 6. 3.GALLERY
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BEFORE
AFTER
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BEFORE
AFTER
Figure 6. 5.LIGHTING
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BEFORE
AFTER
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CHAPTER 7- UPDATING THE MANUAL
As features of the dam and appurtenant structures change occasionally, the O&M Manual must be edited and portions rewritten to reflect these changes. This important task is often ignored. Updating information in the O&M Manual should be done whenever major changes like construction of an additional spillway, construction of dam on the upstream etc. take place.
Aspects to be considered when updating include: Increase/decrease in the frequency of an inspection or the maintenance routine based on additional data/ experience acquired. Changes in the operation and/or maintenance procedures based on additional data/experience acquired. Alterations to the project data because of changes/modifications in the dam by way of additional spillway etc.
All up-dates/revisions of the O&M Manual need to be sent to all the locations/addresses to whom the copies of the original O&M Manual had been sent earlier. It is recommended that O&M Manuals be reviewed/ updated after every 10 years by the respective Dam Owners.
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Annexure -A ( Basic drawings)
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Annexure -B Hydrological Review Report
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Annexure –C Gate Manufacturer’s Manual – Not available Annexure -D Check List for Inspection
Composite Dam Checklist
SN Inspection Items Response Observations and Condition Recommendation s, (Unsatisfactory / if any, of the Poor/ Fair/ authorized Satisfactory Y N NA inspecting officer
A- Reservoir A-1.1 General condition
1.1.1 Is the reservoir water level unusually - - - - high or low?
1.1.2 Are there signs of decline in water - - - - quality?
1.1.3 Are there signs of recent sediment - - - - deposition?
1.1.4 Is floating debris present - - - -
1.1.5 Any indications of major active or - - - - inactive landslide area in the reservoir rim? If so, indicate their locations and extent.
1.1.6 Are there people or livestock in and - - - - around reservoir?
1.1.7 Any other issues? - - - -
B-Dam and Dam Reach (Embankment)
B-1.1 General Condition
1.1.1 Any major alterations or changes to the dam since the last inspection?
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1.1.2 Is there any new nearby development in the downstream floodplain?
1.1.3 Any misalignment of poles, fencing or walls due to dam movement?
B-1.2 Upstream Slope
1.2.1 Any signs of bulging or concavity (depressions)? If so, indicate their locations and extent. (Check up the cross-sections with tape and level at random locations at least two)
1.2.2 Does the section of the dam and upstream slope appear structurally sound and stable?
1.2.3 Presence of longitudinal or transvers cracks?
1.2.4 Any signs of distress to stability of slopes noticed at any time in any part of the dam? If so, give brief details of the incidents and location, the method of treatment adopted and its effectiveness. Indicate the general condition of upstream pitching.
1.2.5 Any degradation to slope protection (rip-rap)?
1.2.6 Is there any profuse growth of bushes or weeds over any portion of the dam? If so, indicate the locations
1.2.7 Does the upstream slope shows existence of crab holes or holes made by rodents or burrowing animals or ant hills? If so, indicate the locations.
1.2.8 Any other issues?
B-1.3 Crest of Dam
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1.3.1 Is the crest profile at proper elevation? ( To be test checked at random locations by taking level)
1.3.2 Does it show any signs of excessive and/ or uneven settlement? If so, indicate such locations and extent of settlement. ( Surface settlement points must be installed for observing this aspect)
1.3.3 Is the surface of the crest free from undulations and local depressions or heaving?
1.3.4 Does it provide an all -weather road surface?
1.3.5 Any degradation to access road ( sealed/ unsealed)?
1.3.6 Does it develop any visible cracks in transverse or longitudinal directions? If so, attach a map showing heir locations and extent. Depth of cracks must be ascertained by taking open trenches extending below the bottom of cracks.
1.3.7 Have the edges of the crest gotten eroded and cut up resulting in reduced effective width?
1.3.8 Is the crest free from local slops throughout its length on either sides?
1.3.9 Do the headers, guard stones and parapet wall provided at the edges of the crest appear in proper profile and plumb?
1.3.10 Any degradation to upstream parapet or downstream curb wall?
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1.3.11 Evidence of livestock on dam crest?
1.3.12 Trees or profuse growth of weeds/ bushes at any location?
1.3.13 Proper lighting arrangement at dam top?
1.3.14 Any other issues?
B-1.4 Downstream Slope
1.4.1 Any signs of bulging or concavity (depressions)?
1.4.2 Are there any wet or slushy patches or any concentrated leaks, spring or trickles observed on the downstream slopes or the toe? If so, indicate their locations and extent, Please look out for patches of extensive vegetation growth and examine them carefully and record the findings,
1.4.3 Presence of longitudinal or transvers cracks?
1.4.4 Any signs of distress to the stability of slopes?
1.4.5 Are rain cuts/ erosion channels present at any location?
1.4.6 Are all the rain cuts and erosion channels properly treated and made good? Please indicate location of recurring damages, if any.
1.4.7 Is there any profuse growth of bushes or weeds over any portion of the dam? If so, indicate the locations
1.4.8 Does the downstream slope show existence of crab holes or holes made by rodents or burrowing animals or ant hills? If so, indicate
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the locations.
1.4.9 Any other degradation to slope protecting ( turfing)? Indicate the general condition of downstream pitching/ turfing and rock toe.
1.4.10 Is the downstream area clear of debris and freely draining?
1.4.11 Any other issues?
B-1.5 Downstream Drainage
1.5.1 Are there any signs of water logging, slushy conditions or growth of aquatic weeds on the downstream of the dam? To be checked up to 300 m downstream of toe
1.5.2 Are there any standing pools of water in the downstream of dam? If so, give their locations and extent. To be checked up to 300 m downstream of toe
1.5.3 Are there any boils observed in the vicinity of the downstream toe of the dam? If so, give locations.
1.5.4 Is the downstream area sufficiently clear and freely draining?
1.5.5 What is the depth of ground water table on the downstream as evident from the existing wells in the vicinity of the dam? To be checked up to 300m downstream of toe.
1.5.6 Does the water table show any marked variation in accordance with the variations in reservoir water level?
1.5.7 Are all the exposed drains working satisfactorily?
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1.5.8 Toe drains and cross drains:
- i. Are the portions of longitudinal toe drain and exposed cross drains beyond the downstream toe of the dam in regular section and freely draining?
- ii. Is the pitching to these drains intact?
- iii. Is there any weed growth in these drains?
- iv. Any other defects noticed in the drains?
1.5.9 Outfall Drain:
1.5.12 (a) Is the outfall drain in proper shape and grade and freely draining?
1.5.13 (b) Is the outfall drain properly cleaned and maintained?
1.5.14 Does the outfall drain show any stagnant pools of water or weed growth?
B-1.6 Surface Drainage of Downstream Slope
1.6.1 Is the condition of the downstream slope drainage arrangements, If provided, satisfactory?
1.6.2 Is the paving to these drains intact?
1.6.3 Are all the drains properly maintained and free of vegetation growth and debris?
1.6.4 Does the slope have a tendency to develop severe rain cuts at any location?
1.6.5 Any Other defects noticed in the surface drainage of downstream
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slope?
B-1.7 Seepage Measurement
1.7.1 Is the quantity of seepage being daily or periodically measured and recorded? Please check the registers and record observations.
1.7.2 Does it show any abnormal rise or fall? If so, explain if it has any relation to a certain reservoir level elevation.
1.7.3 Does the seepage show a turbid colour at any stage? Indicate if such a phenomenon has been observed at any stage, at any location in the past.
1.7.4 What is the measured rate of seepage flow with date and reservoir level:
- i. On the day of present inspection
- ii. Maximum since last June
- iii. Minimum since last June
1.7.5 Is the portion upstream and downstream of measuring points of seepage easily accessible with proper steps and paths and free of vegetation growth?
1.7.6 Are the measuring points properly located. Constructed and maintained so as to give accurate and reliable measurements of seepage in accordance with the relevant IS codes?
1.7.7 Is the method of taking seepage measurements satisfactory?
B-1.8 Breaching Section (if provided)
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1.8.1 Is the breaching section easily accessible?
1.8.2 Is the condition of the breaching section satisfactory?
1.8.3 Is the note of instructions as to when and how to operate the breaching section available on record?
1.8.4 For reconstruction after the breach, are the following items decided in advance?
- (a) Quarry for embankment material
- (b) Suitable routes of access
1.8.5 Is the maintenance staff fully aware of the instruction related to operating of the beaching section and for reconstruction after the breach?
1.8.6 Ascertain and indicate the latest event of operation of breaching section and its performance.
1.8.7 Evidence of recent degradation?
1.8.8 Any other issues?
B-1.9 Junction of Earth work with Masonry/ Concrete dam sections and outlets
1.9.1 Is there any existence of leaks, springs or wet spots in the earth work in the vicinity of the junction between earth work and masonry works? If so, please indicate the approximate rate and colour of the leakage and if it turns turbid at any time., Please ascertain from enquiries and record the findings.
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vicinity of masonry or concrete? If so, indicate the locations and the exact nature of deficiency.
1.9.3 Is there any tendency for surface erosion or slope instability at the junction?
1.9.4 If the outlet conduit is located in the earth dam section, is the entire length of the conduit in perfect order and profile and free from offsets, open joints, cracks and leakage? Examine the conduit carefully from the downstream or from inside, if possible, and indicate the deficiencies observed, if any?
1.9.5 Any other issues?
B-1.10 Relief wells
1.10.1 Are the relief wells in good working condition and functioning well?
1.10.2 Are the relief walls properly surged and cleaned periodically?
1.10.3 Please indicate the dates of last surging and cleaning and the next surging due,
1.10.4 Are the necessary plant and equipment for cleaning the relief wells, available with the office?
1.10.5 Is the record of periodical measurements of discharge from each relief well maintained? If so, indicate total discharge and maximum discharge observed from a single well of the date of inspection.
B-1.11 Abutment Contacts
1.11.1 Any presence of leaks, springs or wet
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spots near the abutment?
1.11.2 Any presence of cracking, settlement or upheaval of earth work?
1.11.3 Any evidence of erosion or slope instability?
1.11.4 Trees or profuse growth of weeds/ bushes?
1.11.5 Any degradation to up/ downstream slope protection (rip-rap, turfing)?
1.11.6 Any other issues?
C Dam and Dam Block/ Reach (Concrete/ Masonry)
1.1 General Condition
1.1.1 Any major alterations or changes to the dam since the last inspection?
1.1.2 Is there any new nearby development in the downstream floodplain?
1.1.3 Any misalignment of poles, fencing or walls due to dam movement?
C1.2 Upstream Face
1.2.1 Evidence of surface defects (honey combing, staining, stratification)?
1.2.2 Concrete/ masonry deterioration (spalling, leaching, disintegration)?
1.2.3 Is cracking present (structural, thermal, along joints)?
1.2.4 Evidence of differential settlement (displaced/ offset/ open joints)?
1.2.5 Presence of vegetation (growth in joints between blocks)?
1.2.6 Evidence to any other damage to
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joints and/ water stops?
1.2.7 Any other issues?
C1.3 Crest of Dam
1.3.1 Evidence of differential settlement (displaced/ offset/ open joints)?
1.3.2 Presence of cracking (structural, thermal, along joints)?
1.3.3 Profuse growth of weeds/ grass/ plants at any location?
1.3.4 Any degradation to access road?
1.3.5 Any degradation to upstream parapet or downstream curb wall?
1.3.6 Any other issues?
C1.4 Downstream Face
1.4.1 Evidence of surface defects (honey- combing, staining, stratification)?
1.4.2 Concrete/ masonry deterioration (spalling, leaching, disintegration)?
1.4.3 Presence of cracking (structural, thermal, along joints)?
1.4.4 Evidence of differential settlement (displaced/ offset/ open joints)?
1.4.5 Presence of vegetation (growth in joints between blocks)?
1.4.6 Evidence of any other damage to joints and/ water stops?
1.4.7 Excessive seepage/ sweating at any location on downstream face?
1.4.8 Significant leakage at any location on downstream face?
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1.4.9 Any other issues?
C1.5 Abutment Contacts
1.5.1 Any presence of leaks, springs or wet spots in vicinity of abutment?
1.5.2 Any presence of cracking or settlement?
1.5.3 Profuse growth of weeds/ grass/ plants at any location?
1.5.4 Any other issues?
D Gallery/ Shaft and Drainage
D-1.1 General Condition
1.1.1 Slushy condition or water logging immediately downstream of dam?
1.1.2 Any evidence of boiling in vicinity of dam toe?
D-1.2 Gallery/ Shaft Condition
1.2.1 Any problems accessing or inspection gallery/ shaft (obstruction)?
1.2.2 Any safety issues (inadequate handrails, lighting or ventilation)?
1.2.3 Problems of inadequate drainage (slippery stairs, water logging of gallery, clogged porous or foundation drains)?
1.2.4 Evidence of differential settlement (displaced/ offset/ open joints)?
1.2.5 Excessive seepage/ sweating at any location along gallery/ shaft?
1.2.6 Significant or excessive leakage at any location along gallery/ shaft/ porous drain? If yes, provide
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location(s)
1.2.7 Are proper arrangements made for the measurement of seepage into the gallery?
1.2.8 Is the seepage measured separately from porous pipes, Foundation drains and Monolith Joints?
1.2.9 Are the above arrangements satisfactory?
1.2.10 Has there been substantial progressive reduction in the seepage through the foundations? Indicate if it is due to choking of the drain holes and if so, indicate the number of choked holes.
1.2.11 Are all the foundation and porous holes periodically cleaned with reaming tool and air water jetting? Indicate the last date of such cleaning and extent of variation observed in the seepage discharge before and after the cleaning.
1.2.12 Is the seepage water and the deposit, if any, from the seepage being regularly examined for chemical composition? If so, indicate the result and the probable source of dissolved salts, if any.
1.2.13 Are any seepage water springs observed in the downstream area any where? If so, indicate the locations and state the physical nature of this seepage. Look out for such seepage spots particularly near the dykes, fault Zone etc. Ascertain if chemical testings are made of water samples from such springs for
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dissolved salts.
1.2.14 Is there any leachate deposition? If yes provide location
1.2.15 Any other issues?
D-1.3 Drain Condition
1.3.1 Is the flow in the drain unusually high or low?
1.3.2 Presence of calcium or other deposits in drain?
1.3.3 Is the dewatering pumping station fully operational?
1.3.4 Any problem inspecting the pump?
1.3.5 Any obstruction preventing or impairing smooth operation?
1.3.6 Any deterioration of pump and associated equipment?
1.3.7 Is the sump well clean and maintained?
1.3.8 Is the V-notch before sump well cleaned and maintained?
1.3.9 Any other evidence of the drain being blocked/ Having reduced section?
1.3.10 Is the flow in the drain noticeably sporadic/ irregular?
1.3.11 Does the drainage water have unusual color (leachate)?
1.3.12 Any other issues?
D-1.4 Body Wall (masonry/ Concrete) of NOF Dam
1.4.1 What is the total seepage into gallery from porous pipes in the dam at lake
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full condition? Compare it with the seepage when the reservoir was first filled.(For the corresponding water level)
1.4.2 Has there been substantial reduction in this seepage? Ascertain and indicate the probable reasons therefore.
1.4.3 Has there been a tendency for gradual reduction of drainage through pipes and progressive appearance of sweating on the downstream face of the dam?
1.4.4 Has there been considerable leaching from the seepage water and deposition of lime near the seepage exit spots?
1.4.5 Are the samples of the seepage water and reservoir water being regularly tested for reactive and corrosive properties?
1.4.6 Is there excessive seepage, sweating at any locations on the downstream face of the dam? (Examine the monolith or construction joints for such seepage and leaching and indicate the findings).
1.4.7 Is there any swelling or cracking observed on the downstream face especially near the points of concentration of stresses like the toe or locations of abrupt change in geometry of the face of opening? If so, indicate the details of observations.
1.4.8 Is the pointing on upstream face of the dam in good condition? If not, indicate the nature and extent of
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deficiency.
1.4.9 Are the registers and graphs showing the periodical measurements of seepage discharge from the porous drains in the gallery and from the downstream face at various lake levels maintained at site?
E Spillway land Energy Dissipation Structure
E-1.1 Spillway
1.1.1 Any problems inspecting spillway (obstructed access, damaged catwalk)?
1.1.2 Any obstructions in or immediately downstream of the spillway?
1.1.3 Evidence of abrasion, cavitation or scour on glacis (e.g. exposed reinforcement)?
1.1.4 Presence of displaced, offset or open joints?
1.1.5 Presence of cracking (structural, thermal, along joints)?
1.1.6 Evidence of surface defects (honeycombing, staining, stratification)?
1.1.7 Concrete/ masonry deterioration (spalling, leaching, disintegration)?
1.1.8 Presence of vegetation (growth in joints between blocks)?
1.1.9 Evidence of any other damage to joints and/ water stops?
1.1.10 Excessive seepage/ sweating at any location on spillway glacis?
1.1.11 Significant leakage at any location on
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spillway glacis?
1.1.12 Any other issues?
E 1.2 Waste Weir Bar and Tail Channel
Is the Concrete/ masonry spillway bar in good condition? Indicate if there is any leakage through the masonry or from the foundation. If so, what remedial measures are proposed/ taken for minimizing the leakage? Is the record of leakage measurement maintained? What is the quantity of seepage/ Leakage on the date of inspection?
Is the coping over the spillway bar in good condition?
Does the upstream and downstream face of waste weir bar need pointing?
Is there any scouring on downstream side of the bar and/ or EDA? If so what remedial measures are proposed/ taken?
Are there any damages or undermining to guide wall and other appurtenants? If so, indicate what remedial measures are proposed/ taken.
E 1.3 Structural performance of the ‘NOF’ and ‘OF’ Portions of Dam Foundations
1.3.1 Are there any signs of structural distress noticed in the dam spillway and foundations in the form of-
- i. Excessive deflection with respect to permissible deflection at the time of design.
- ii. Tendency of gradual sliding
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- iii. Cracking and upheaval or settlement in any part of the body wall or foundations.
- iv. Excessive uplift.
- v. Excessive seepage and leaching through the body of the dam and the foundation.
1.3.2 Conspicuous weathering of materials or components in any portion of the body wall or the foundations.
E 1.4 Energy Dissipation Structure
1.4.1 Any problems inspecting energy dissipation structure?
1.4.2 Any obstructions in or immediately downstream of dissipation structure?
1.4.3 Evidence of abrasion, cavitation or scour on dissipation structure?
1.4.4 Presence of displaced, offste or open joints?
1.4.5 Presence of cracking (structural, thermal, along joints)?
1.4.6 Evidence of surface defect (honeycombing, staining, stratification)?
1.4.7 Concrete/ masonry deterioration 9spalling, leaching, disintegration)?
1.4.8 Presence of vegetation (growth in joints between blocks)?
1.4.9 Evidence of any other damage to joints?
1.4.10 Any problems with under drainage (blockage of open drain holes)?
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1.4.11 Can the tail pond be drained easily for inspection of the stilling basin or bucket? If not, indicate the alternatives available for dewatering. Please ascertain and indicate the last event of inspection of stilling basin(or bucket).
1.4.12 From the examination of the levels and contour plans and reference marks in tail channel; is there progressive erosion and retrogression in the tail channel? If so, indicate the extent and location of such erosion with reference to the various components of dam, spillway, outlet, power house etc.
1.4.13 Is the concrete surface of the stilling basin and apron (or bucket) in good condition?
1.4.14 Are there any indications of pitting, cracking, spalling or wearing of the surface of bedding concrete? If so, please give details of the nature and extent of the damage.
1.4.15 Is there any indication of abrasion and cavitation damage (pitting of concrete) especially at friction blocks, chute blocks and slotted roller teeth, the surface near the lower tangent point and the end sill? If so, please give the details of nature and extent of damage.
1.4.16 Is the under drainage of the stilling basin (or bucket) satisfactory? Are all the open drain holes clear and functioning well?
1.4.17 Any other issues?
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G 1.5 Wall; Guide wall/ Divide walls/ Junction walls/ Return walls/ Spray walls etc.
1.5.1 Are all the locations of such wall accessible for inspection, maintenance and repairs?
1.5.2 Is the drainage of back sides of the walls (wherever applicable) from the weep holes satisfactory? If not, indicate the nature of deficiencies.
1.5.3 Is there any tendency for the water to undercut the ends of the walls?
1.5.4 Is there any foundation erosion or scour noticed in the vicinity of such walls? If so, give the detains of nature and extent of such damage.
1.5.5 Is there any surface erosion/ damage caused, to face or body of such walls?
1.5.6 Do any of the walls show symptoms of unusual settlement, developments of cracks and tilting? If so, give details of the defects notice.
1.5.7 Is there any damage to guide bunds? If so, give details of the damage.
G 1.6 End Weir
Is it accessible?
Is there any erosion, pitting or spalling of the concrete or masonry surface? If so, give details
Is there any scour noticed on the immediate downstream of such weir? If so, give details of location and extent of such damage.
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damage to the surface of buckets baffle blocks. Apron and end sill?
Is the hydraulic performance in agreement with the results of model studies? (wherever applicable)
Ascertain the performance from observed tail water rating curves and deficient observation, if any, such as sweep outs and excessive erosion under plunge pools and locations of secondary rollers and retrogression
F Intake/ Outlet and Water conveyance Structure
F 1.1 Intake/ Outlet Structure
1.1.1 Any problems inspection intake/ outlet structure (obstructed/ unsafe access)?
1.1.2 Any obstructions in upstream or downstream of intake/ outlet structure?
1.1.3 Evidence of abrasion cavitation or scour on intake/ outlet structure?
1.1.4 Any evidence of structural distress (displaced/ offset/ open joints, cracking)?
1.1.5 Any evidence of surface defects and/ or concrete/ masonry deterioration?
1.1.6 Any other issues?
F 1.2 Water Conveyance Structure
1.2.1 Any problems inspecting intake/ outlet structure (obstructed/ unsafe access)?
1.2.2 Any obstructions in upstream or downstream of water conveyance
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structure?
1.2.3 Evidence of abrasion cavitation or scour on structure?
1.2.4 Any evidence of structural distress (displaced/ offset/ open joints, cracking)?
1.2.5 Any evidence of surface defects and. Or material deterioration?
1.2.6 Any evidence of seepage or leakage from water conveyance structure?
1.2.7 Any other issues?
G-1 Hydro-Mechanical Component and Pump
G 1.1 Spillway Gates (Radial gates, Vertical lift gates, Automatic gates)
1.1.1 Any problems inspecting gate/ Stop- logs (obstructed/ unsafe access)?
1.1.2 Is the condition of the steel surface and the surface paint deteriorated?
1.1.3 Are any connection bolts of rubber seals loosened or damaged? If so, indicate the details of defects.
1.1.4 Do any of the rubber seals show signs of weathering, hardening, cracking or tearing and damage?
1.1.5 Are the rubber seals of side and bottom touching uniformly all along the sealing surface?
1.1.6 Do the rollers (wherever applicable) touch the rack plates uniformly? Are the rollers well lubricated?
1.1.7 Are the embedded parts of spillway gates, emergency gates and stop-logs in sound condition and free from corrosion, uneven wear, cracking,
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chipping and dents? If not, state the nature of defects or deficiencies and observation, if any, regarding such defects.
1.1.8 Are the following members and welded, bolted and riveted connections structurally sound? If not, please give details of any uneven wear, uneven bearing, cracking, chipping and dents and indicate the findings:
(1) Gate leaf and stiffeners
(2) End arms
(3) Trunnion girders/ Yoke girder (4) Stop logs
(5) Lifting beams
(6) Gantry cranes
(7) Tracks
(8) Trunnion bracket
(9) Chains/ wire ropes
(10) Bridge structure
1.1.9 Are the trunnion bearings of radial gates properly lubricated?
1.1.10 Is there any damage or wear caused to the seal plates? If so, indicate the nature of damage noticed.
1.1.11 Are any of the mechanical or structural components and fastners or seals subjected to excessive wear? If so, please give details.
1.1.12 Is there any tendency for recurring damage to any particular
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component? If so, please give details.
1.1.13 Is sufficient stock of spares which need frequent replacement maintained at the site?
1.1.14 Any issues with storage of equipment (emergency stop logs, lifting beam and gate leaves)?
1.1.15 Any deterioration, corrosion? Scaling? Pitting? Or cracking? Of equipment (connecting bolts, welds?)
1.1.16 Any obstructions preventing or impairing smooth operation?
1.1.17 Any problems with the rollers (not touching tracks, inadequate lubrification)?
1.1.18 Any debris, etc., in the gate grooves?
1.1.19 Any damages to Radial Gate trunnion pins? Gate arms? Lubrication? etc.?
1.1.20 Any damage to embedded parts above waterline? Access structure?
1.1.21 Any damage to concrete grooves?
1.1.22 Is the staff posted at the site for maintenance and operation of gates, hoists, equipment’s and electrical installations, well experienced, fully trained and conversant with the job requirements and responsibilities?
1.1.23 Are the following documents maintained at the respective location of all the units?
- (1)Maintenance schedules specifying each operation, its frequency and ‘due’ and ‘done’ dates.
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- (2)Operating instructions with ‘dos’ and ‘don’t’ for all operational units.
1.1.24 Are the trunnion hub and the brackets well maintained?
1.1.25 Are the trunnions likely to get submerged during actual working of the spillway? If so, ascertain the causes for the same and specify, Please enquire for occurrence of such events, if any.
1.1.26 Are all the nuts of connecting bolts and anchorages properly tightened?
1.1.27 Any other issues?
G 1.2 Hoists, Cranes and Operating Mechanisms
1.2.1 Are the hoists working satisfactorily?
1.2.2 Any problems inspecting hoist/ crane/ operating mechanism?
1.2.3 Is sufficient stock of spares which need frequent replacement maintained at the sits?
1.2.4 Is the full length of the chains or wire rope of the hoist in sound condition and free from broken strands?
1.2.5 Is the electrical wiring in sound condition?
1.2.6 Is the alternative power system for gate operation working properly?
1.2.7 Is the alternate hand operation system of hoist working properly?
1.2.8 Any deterioration of equipment (connecting bolts, welds, surface paint work?
1.2.9 Any wear or damage to wire cables
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and other moving parts?
1.2.10 Any obstructions preventing or impairing smooth operation?
1.2.11 Any health and safety concerns (e.g. lack of “danger” sign during maintenance)?
1.2.12 Any other issues?
G 1.3 Spillway Bridge, Hoist Bridge, Trunnion Level Bridge Catwalks
1.3.1 Are the decking, girders and structural supports of spillway bridge, hoist bridge, trunnion level bridge and catwalks structurally sound?
1.3.2 Is the chequered platform of the bridge structurally sound and safe?
1.3.3 Is there satisfactory arrangement to prevent unauthorized entry in to the control structures and bridges?
1.3.4 Are the structural members and joint sound and free from corrosion?
1.3.5 When were the steel components painted last?
1.3.6 Is the surface of steel work and paints satisfactory?
1.3.7 Is the parapet or railing over the bridges sound, safe and painted?
1.3.8 Is the walkway properly anchored to the piers?
1.3.9 Are the track rails for gantry cranes structurally sound and intact?
G 1.4 Valves
1.4.1 Any problems inspecting valve?
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1.4.2 Any obstructions preventing or impairing smooth operation?
1.4.3 Any deterioration of valve and associated equipment?
1.4.4 Any other issues?
G1.8 Trash Racks
1.5.1 Is the trash rack fixed or movable?
1.5.2 What is the mode of cleaning? Is it manual or by TRCM?
1.5.3 Is the welding work on Trash Rack in sound health?
1.5.4 Any problems inspecting trash rack?
1.5.5 Problems of excessive debris and/ or inadequate cleaning?
1.5.6 Any deterioration of trash rack (rust, corrosion, and damaged blades)?
1.5.7 Any other issues?
G 1.9 Trash Rack Cleaning Machines
1.6.1 Any problems inspecting trash rack cleaning machine?
1.6.2 Missing or inadequate spare parts (particularly requiring regular replacement)?
1.6.3 Any deterioration of equipment (wheel trolleys, gantry structures, operating mechanism, connecting bolts, welds, surface, paint work?
1.6.4 Any wear or damage to wire cables and other moving parts?
1.6.5 Any obstructions preventing or impairing smooth operation?
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1.6.6 Missing or inadequate provision of back-up/ standby power supply?
1.6.7 Any health and safety concerns (e.g. lack of “danger” sign during maintenance)?
1.6.8 Any other issues?
G 1.10 Pumps
1.7.1 Any problems inspecting pump?
1.7.2 Any obstructions preventing or impairing smooth operation?
1.7.3 Any deterioration of pump and associated equipment?
1.7.4 Any other issues?
G 1.11 Approach bridge, operation platform and cabin (for outlets):
1.8.1 Are the decking, girders and structural supports of approach bridge structurally sound?
1.8.2 Is the floor of the operating platform structurally sound and safe?
1.8.3 Is there satisfactory arrangement to prevent unauthorized entry into the control structures of the outlet?
1.8.4 Are the structural members and joints sound and free from corrosion?
1.8.5 When were the steel components painted last?
1.8.6 Is the surface of steel work and paint satisfactory?
1.8.7 Is the parapet or railing over the control tower, operating platform and approach bridge sound and safe?
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G 1.12 Outlet
1.9.1 Is the air vent periodically cleaned?
1.9.2 Are there any structural damages to the intake well?
1.9.3 Is there any leakage observed through the well proper and the conduit concrete or masonry? If so, give details of its location and extent.
1.9.4 Is there any damage noticed to the conduit concrete, breast wall and gate slots?
1.9.5 Is the bye-pass valve/ filling in valve (wherever provided) operating satisfactory?
- Take operation trials of the following as provided and record the observations and defects noticed, if any.
- (1)Service gate(s)
- (2)Emergency gate(s)
- (3)Stop-log gate(s)
- (4)Sluice valves
- Note-
- (i)The operating trial for the emergency gate shall be taken with service gate in partially open position to test the capability of emergency gate for self-closing under these conditions. The trial for the operation of the emergency gate under balanced condition of water pressure also needs to be taken
- (ii)To guard against the possibility of outlet gate hoist being operated
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forcibly after closed position of gate a “Distinctive Mark” should be insisted or check the functioning of the limit switches.
1.9.6 Are there vibrations and noise noticed in operation of out-let gates at any time? If so, please indicate if periodical observations have been taken to ascertain their severity.
1.9.7 Is the energy dissipation arrangement working satisfactorily for all the discharges?
1.9.8 Is there any structural damage to the energy dissipation structure? If so, give details of nature and extent of damage.
1.9.9 Is the conduit structurally sound and reasonably leak proof? If not, give details of nature and extent of the defects.
1.9.10 Is there any seepage noticed around the conduit as ascertained from the observations of the downstream conditions? If so, please indicate if it is likely to cause erosion and piping (in case of earth dams).
G 1.13 Outlet Gates
1.10.1 Is the surface of gates and the paint deteriorated?
1.10.2 Are the connecting bolts of rubber seals properly tightened or damaged?
1.10.3 Do the rubber seals show signs of weathering and damage and need replacements?
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1.10.4 Are the rubber seals of sides and bottom touching the bearing surface uniformly?
1.10.5 Do all the rollers touch the track plates?
1.10.6 Are the rollers well lubricated?
1.10.7 Are the stem rods for lifting the gates perfectly straight?
1.10.8 Is the operation of outlet gates smooth?
1.10.9 Are the actual operations of lifting and lowering of the gates and hoist mechanisms adequate and smooth?
1.10.10 Are all the gears and hoist mechanisms well lubricated?
1.10.11 Is the storing arrangement for emergency gate leaves and the stop logs in satisfactory condition?
1.10.12 Are the seal plates/ seats in sound condition?
1.10.13 Is the full length of wire rope (wherever applicable) of the hoist in serviceable condition and free from any broken strands?
1.10.14 Are all the nuts of connecting bolt and anchors properly tightened?
1.10.15 Are all the lifting beams in proper working order and in levelled condition? If not, ascertain the nature and extent of problems.
1.10.16 Do any of the mechanical or structural parts of the gate, fasteners of hoist show signs of excessive wear? If so, please give details.
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1.10.17 Is there any tendency for recurring damage to any particular component or components? If so, please give details.
1.10.18 Is sufficient stock of spares, which need frequent replacement, maintained at the site?
G 1.14 River Outlet/ River Sluice
1.11.1 Is the overall condition of river outlet works/ river sluices satisfactory?
1.11.2 Is the operation of the gate (Service/ Emergency/ Stop-log) satisfactory as ascertained by taking operating trial? If not, indicate the defects noticed.
1.11.3 Are the trash racks (wherever provided) cleaned before monsoon?
1.11.4 Is there excessive silting on the upstream of the sluice?
1.11.5 When were the gates last opened for desilting, etc.?
1.11.6 Please indicate the approximate quantity of the leakage through the gates, if any.
1.11.7 Is there any seepage or leakage through the conduit surface?
1.11.8 Is there any damage to the upstream and downstream convergence of the conduit?
1.11.9 Is the condition of energy dissipation arrangement satisfactory? If not, indicate nature and extent of damage.
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damage.
H-1 Access Road
H 1.1 General Condition
1.1.1 Any problems ensuring security of dam site (including gates and fencing)?
1.1.2 Is there a properly constructed and well maintained all weather access road to the dam site?
1.1.3 What is the type of the pavement of the access road and its condition?
1.1.4 Are there properly constructed and well maintained access road arrangements to the following components for inspection, maintenance and repairs? Top of Dam Spillway Gates and hoisting arrangement Drainage gallery, adits and exits Bridge structure Downstream stilling basin Junction and abutments Outlet control tower Outlet gates Toe of earth dam, downstream drainage arrangements and berms. All saddle dams.
1.1.5 Are all the masonry structures on various access roads in good condition?
1.1.6 Are all the structures on the access roads adequately safe for allowing passage of plant machinery for emergent repairs?
1.1.7 Any obstructions along or at entrance to access road (temporary or long-term)?
1.1.8 Any solpe stability issues (road
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embankment or adjacent slopes)?
1.1.9 Profuse growth of weeds/ grass on or in vicinity of access road?
1.1.10 Any drainage problems (standing water on or adjacent to road)?
1.1.11 Any other degradation to road surface (ruts, potholes, cavities, cracking)?
1.1.12 Any other issues?
I-1 Instrumentation
I-1.1 General Condition
1.1.1 Are all the instruments installed accessible? (Attach separate list).
1.1.2 Are all the locations properly lighted, ventilated and adequately protected from possibilities of damage?
1.1.3 Any problems inspecting instrument (obstructed/ unsafe access)?
1.1.4 Is the instrument vulnerable to damage or theft (inadequate protection)?
1.1.5 Any problems ensuring correct functioning of instrument (lighting, ventilation)?
1.1.6 Any evidence of degradation to condition of instrument (rusting, vandalism)?
1.1.7 Are all the instruments inworking order? Ascertain the cases of instruments going out to order and indicate.
1.1.8 Are all the registers of observations posted up-to-date? Please take test
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observations and initial the register.
1.1.9 Are all the plotting of the instrumentation data completed up- to-date?
1.1.10 Are sufficient stocks of spares, gauges, master gauges, stationary items etc., maintained at the site for uninterrupted data collection?
1.1.11 Operator or public safety issues?
1.1.12 Any other issues?
I-1.2 Communication Facilities
1.2.1 Are following facilities available at dam site?
- (1)Wireless Telephone/ mobile/ Fax/ Internet
1.2.2 Any other issue (please indicate part, location, etc., as necessary)
K-1 Emergency Preparedness
K-1.1 Emergency Action Plan
1.1.1 Is the Emergency Action Plan (EAP) prepared for the dam as per the national guidelines? If not, the expected date of preparation of guidelines.
1.1.2 When EAP was last updated?
1.1.3 If not, are any dam staff unaware or insufficiently conversant with the EAP?
1.1.4 Any concerned authorities unaware or insufficiently conversant with the EAP?
1.1.5 Are communication directories/ contact details and other dynamic 144
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information are being updated annually?
1.1.6 Any problems accessing or operating the communication/ warning system?
1.1.7 Are inundation maps updated and available to concerned authorities?
1.1.8 Are the concerned authorities informed about the system of emergency reporting procedures and warning?
1.1.9 Are available safety spots on the downstream of the dam identified and made known to the concerned authorities?
1.1.10 Are adequate warning devices and facilities provided at the dam?
1.1.11 Are proper arrangements made for security of the dam and preventing cases of unauthorized trespass, vandalism and sabotage to the dam works?
1.1.12 Date of last annual stakeholder consultation meeting along with mock drill exercise conducted
1.1.13 Has the EAP been disseminated to all the concerned stakeholders?
1.1.14 Any other issues?
K-1.2 Inspection of Records
1.2.1 Have the following dam safety Documents been prepared and approved by the competent authority?
- I.As Built Drawings
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- II.EAP
- III. Completion Report
- IV. Data Book
- V. O and M manual
1.2.2 Are the relevant documents reviewed and updated from time to time?
1.2.3 Are all the members of the maintenance staff adequately trained and fully conversant with their responsibilities concerning.
- (a)Designer’s operation Criteria.
- (b)Standing Operating Procedures.
- (c)Maintenance and Vigilance Procedures of the dam.
- (d)Maintenance and operation of all control equipment’s.
- (e)Reservoir Operation Schedules, Gate Operation Schedule
- (f)Maintenance and Operation of all instruments.
- (g)Identification of signs of deficient behavior.
- (h)Reporting Procedures of emergency situations.
- (i)Emergency repairs.
L-1.1 Inspection Photo graphs
1.1.1 Information to be furnished as per Annexure -II
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Annexure- E- DSRP Inspection Report
147
Dam Safety Review Panel (DSRP) Inspection Report of Malankara Dam
JANUARY, 2020
State Dam Safety Organization Department of Water Resources Government of Kerala
148 ACKNOWLEDGEMENT
Dam Safety Review Panel thanks Sri. Joshy K.A, Chief Engineer (I&D), Irrigation Design and research Board, Government of Kerala for taking keen interest in initiating the constitution of DSRP.
The DSRP also acknowledges the Co-operation of all concerned officers of Dam safety organization, Kerala especially Shri Mohammed Basheer Joint Director IDRB Govt. of Kerala and his officers Sri. Shabu Roy, Deputy Director, Bindu L and Deepa K S for coordinating with the Project authorities and making all necessary arrangements and the stay of the members comfortable.
DSRP is also thankful to Sri. Shaji V.S. Chief Engineer, Mechanical, Smt. Jaya P. Nair, Superintending Engineer, Shri. C. S. Sinosh, Executive Engineer and other Engineers for facilitating the work of DSRP. The help rendered in preparation of the report by Sri. James P. John, Assistant Executive Engineer Mechanical is also appreciated. Special thanks to Sri. R Ajithkumar, Assistant Executive Engineer, MVIP Mechanical Sub Division, Thodupuzha, Sabarinath C L, Assistant Engineer, MVIP Section 4/1, Muttom, K Suresh kumar, Assistant Engineer, MVIP Mechanical Section, Thodupuzha, Biju Samuel, Assistant Engineer, MVIP Electrical Section, Muvattupuzha, and Deepa C, Assistant Engineer, MVIP Section 2/1, Muttom for help during field visits and providing the available documents.
The panel extends its appreciation and thanks to all the Field Engineers of this project who assisted in making the data available, taking around and providing inputs as regards to issues identified by them regarding the health of the dam.
149 REPORT OF THE DAM SAFETY REVIEW PANEL ON MUVATTUPUZHA VALLEY IRRIGATION PROJECT –MALANKARA DAM
The Government of Kerala has constituted DSRP vide its order No.G.O. (Rt) No. 293/2019/WRD Dated 27.04.2019. The order constituting DSRP is given at Enclosure – I (a) and I (b). The DSRP consists of the following members:
1) Shri Yogesh Kumar Handa, Chairman 2) Shri Rakesh Chandra Sharma, Member 3) Shri R. K. Gupta, Member 4) Shri Rustam Ali, Member 5) Shri T Sudhakar, Member 6) Shri Rajeev S, Member 7) Shri Shyam Lal Kapil,Member The Chief Engineer, Dam Safety, Kerala vide email dated 19.06.2019 requested the DSRP for visit of Neyyar, Kallada, Pamba and Malankara dam projects. The list of officers of Kerala Government who accompanied the team or participated in the discussion for Malankara Dam is at Enclosure -II. The programme of the visit was as follows; Date Work done 01.07.2019 Arrival of outstation members to Trivandrum. Pre discussion with Chief Engineer regarding format of the report and inputs received for inspection 02.07.2019 Neyyar dam - Inspection and Discussion with Dam Engineers
03.07.2019 Proceeding to Thenmalai – Kallada Dam Inspection and Discussion with Dam Engineer 04.07.2019 Maniyar Dam Pamba - Dam Inspection and Discussion with Dam Engineer 05.07.2019 Malankara Dam - Dam Inspection and Discussion with Dam Engineers 06.07.2019 Departure from Kochi Airport to respective destinations
The Chief Engineer, Dam Safety, Kerala circulated the “Memorandum for the Dam Safety Review Panel (DSRP) for their visit vide email dated 25-06-19. The memorandum, other papers prepared by the project officials and discussions held, formed the basis of this report.
150 CONTENTS
1. GENERAL 1
2. SALIENT FEATURES 3
3. GEOLOGY 3
4. HYDROLOGICAL SAFETY REVIEW 5
5. ISSUES IN DAM AND APPURTENANT STRUCTURES 6
6. MASONRY DAM AND SPILLWAY 8
7. HYDRO MECHANICAL ITEMS 10
8. INSTRUMENTATION 13
9. RECOMMENDED INVESTIGATIONS 13
10. NON-STRUCTURAL MEASURES 15
11. OPERATION & MAINTENANCE MANUAL 15
12. SECURITY ARRANGMENT FOR DAM AND DAM APPURTNENTENANCE 16
13. BASIC DAM FACILITIES 16
14. SOURCE OF SECONDARY REVENUE GENERATION 17
15. FINAL RECOMMENDATIONS 17
16. LIST OF IMPORTANT DOCUMENTS 20
17. PHOTOGRAPHS 43
18. REFERENCES 50
19. LIST OF DOCUMENTS ANNEXED 51
151 1. GENERAL
The Malankara Dam is an earth cum masonry dam across Thodupuzha river, a tributary of Muvattupuzha river. The project is located between Latitude 9° 37` N & 10° 4` N and Longitude 76° 26` E & 76° 49` E. It is located at Muttom in Idukki district near Thodupuzha - Moolamattom road and was constructed for the Muvattupuzha Valley Irrigation Project (MVIP). The dam site is about 27 Km from Muvattupuzha town and 8 Km from Thodupuzha town. There is a network of canal system consisting of two main canals, oneon each bank, its branches and distributaries. It utilizes the tailrace discharge of Idukki Hydroelectric project by inter basin transfer and the runoff from the catchment areaof Thodupuzha river up to Malankara. The project benefits irrigation facilities to 18173 Ha of land on Kottayam, Ernakulam& Idukki Districts. The project also caters to the water needs of the Hindustan News Print factory at Velloor, Kottayam District and providing drinking water facility to KWA schemes and production of 10.5 MW of electricity at Small Hydro Electric Power station at Malankara. The dam consists of a straight gravity dam of RR Masonry on the right bank and in the river portion and earth fill in the left bank. The total length of the dam is 460m and height of 23m. The dam is divided into 12 blocks. The Earthen dam on the left 206m long, has a maximum height of 12m. Masonry dam has a total length of 254m of which 191.90m is non- overflow section and the balance 62.10 m is the overflow section consisting of 6 overflow blocks. The spillway crest level is 36.9m and the top level of dam is EL. 45.00m.
The left bank head sluice is located in block I and right bank sluice is in block 9. The right bank main canal has a length of 28.337 km. with a gross command area of 5883 ha. The left bank main canal has a length of 37.10 km with a gross command area of 15917 ha.
1.1 Dam Safety Inspection Report
1.1.1 Previous Inspection report dated 03/10/2013 is enclosed as Enclosure III.
The following recommendations were made: - a) The studies carried out so far indicate that an SPF value of 2963 m3/sec appears to be reasonable and may be adopted for taking necessary measures for the safety of the dam. b) The DSRP recommends that immediate action may be taken for the preparation of an Emergency Action Plan (EAP) for the project by the project authority.
152 c) For the designed flood value 0f 2963 m3/sec the water level will go above the dam top level. The present spillway is inadequate for tackling the design flood. Further the augmentation of capacity by increasing the length has to ruled out from geological and construction considerations. Other unconventional alternatives are therefore need to be studied. d) The embankment dam should be allowed to overtop during the occurrence of flood by taking following precautions. i. The central impervious core should be raised up to top of dam level to avoid flow through the dam body. ii. Dismantle the parapet wall. Some waves may splash over the top. iii. Strengthen and extend the top road concrete slab to cover some length of u/s slopes. iv. D/s stream slope should be protected by concrete cover in steps to form cascades for energy dissipation in the event of overflow. v. Suitable toe protection is necessary and has to be provided. vi. Length of such provision could be decided after conducting flood routing studies. e) Vegetation on embankment slopes, masonry structures and in the vicinity should be removed. f) The defects in concrete surface in ogee, glacis, piers, contraction joints and other places should be treated with epoxy grout/epoxy mortar/epoxy concrete. g) Low pressure grouting of the dam body should be resorted to, to check the seepage through dam body. h) Also the u/s face of masonry dam should be gunited in two layers with wire mesh sandwiched in between. Alternatively, impervious geomembrane could be installed in place of guniting. Cost and ease in construction could decide the Alternative to be adopted. i) In addition, action to prepare dam break analysis and Emergency Action Plan (EAP) should be initialed. j) Stilling basin should be dewatered and treatment, if any, required in the concrete surface or the toe of end sill should be attended to. k) Drainage holes should be cleared periodically. l) Painting, greasing and oiling of gates and other mechanical equipment should be done periodically as was being done on the day of inspection. m) All measures should be taken to give aesthetic appearance to the dam and surrounding area.
153 n) Necessary security provisions should be made to check the entry of unauthorized persons. o) After finalizing the MWL, the upper nappe profile should be checked to ensure that it is not getting obstructed by gates in open position and trunnion. p) Seepage through the earth dam should be critically observed for migration of soil particles if any. The quantity should also be measured and recorded periodically.
1.2 Past Safety Recommendation/Rehabilitation Works/ Modification done in Chronology of Expert Investigation/ Testing etc.
Table showing works completed in DRIP Phase I
Sl. Description of work No 1 Low pressure grouting with earth slurry to Earthern dam. 2 Drilling, grouting and conducting permeability test of Masonry Dam. 3 Rectification of the damaged toe drain of Earthern dam. Improvements to all weather roads and approaches to Malankara Dam - BT Road from 4 Entrance to Dam top, Perumattom to Dam, Dam Premises & Entrance to camp shed. 5 Protection of Dam and premises. 6 Construction of office building at Dam site. 7 Construction of river training wall at the left side downstream of Malankara Dam Electrical works- Electrification of Police Aid Post, Rest Room and Site Office, Providing High Mast Lighting system, Diesel Generator, Standardization of panels and 8 Cabling, Supply and Replacement and repairs of Motors and Pumps, Repairs to Yard Lights Post Top Lamps and repairs to EI in existing buildings including Quarters, Solar system
2. SALIENT FEATURES
Enclosed as Enclosure IV
3. GEOLOGY
The geological information viz. drill hole logs, foundation grade geological map, test results on construction material test and results of tests conducted on rock samples are not available since the investigation/ construction works were carried out long back. As per
154 DISTRICT RESOURCE MAP
Photo: Map Showing District Resource Map indicating the Geology and Mineral Distribution in Idukki District.
155 available information, various geological formations present around project area are mainly classified as Crystalline rocks of Archaean group (i.e.Migmatite, Khondalite&Charnockite Group) and Residual laterite. The project area falls under migmatitic/ gneissic complex of Archaean era and comprises of biotite gneiss and hornblende – biotite gneiss (composite gneiss). Some exposure of hornblende biotite gneiss is observed near the Malankara dam. The rock mass is dark coloured, very hard-compact & foliated in nature. The Khondalite group is represented by calc- granulite and quartzite. These rocks are seen as linear bands, lenticular bodies mostly within the gneissic terrain. The lateritic soils are most prominent soils observed around the flanks of the project area. The slopes at dam are gentle to moderately steep. As per records and previous dam safety report of 2013, Masonry portion of the dam is founded on gneissic rocks and transition provided to join with the earth dam. Foundation details as well as geological map of foundation of earthen dam are not available with the project, accordingly it is difficult to ascertain the foundation characteristics of the medium over which the earthen structure is constructed. No major instability is visible from immediate upstream to the visible distance as mostly the area is covered with thick vegetation and occasional rock out crops.
4. HYDROLOGICAL SAFETY REVIEW
4.1 General
As per original DPR the Gross storage of the reservoir at FRL EL. 42m is 37Mm3 and dead storage is 10 Mm3. Though, the height of the dam exceeds 15 m, the design discharge at construction stage was 1444.32 cumecs. The deepest foundation EL of masonry dam is EL. 22.0m and Top of dam is at EL 45.0m. Accordingly, originally the dam which was considered in the category of “Intermediate”, and SPF (Standard Project Flood) needs to be revised considering new storm data. 4.2 Design Flood Review
As per DSRP report during 2013, the flood discharge has been evaluated as 2963 m3/sec. It is based on one day observed point rainfall of 660mm at Perumbavoor and has been adopted as candidate rainfall for computing SPF Storm. This value has the concurrence of CWC. The maximum water level achieved after routing 2963 m3/s reaches 48.01m which is about 3.01 m above the top of the dam. During the discussion it was informed by project
156 authorities, that the design flood is being reviewed by CWC and the anticipated final value will be around 2542 m3/s. With this the MWL achieved will be 44.63m with all gates open against top of dam as 45m. Efforts may be made to get the approved value of design flood from CWC considering the flood of 2018.
It has been reported by the Project Authorities that they follow the following procedure for flood management. The shutter opening will be done only after giving proper intimations to Disaster Management Cell at Idukki Collectorate, Disaster Management Cell at Ernakulam Collectorate, Taluk office at Thodupuzha & Muvattupuzha, police stations at Thodupuzha & Muttom, higher officers of Irrigation Department, concerned LSGD Institutions, local visual and news medias and only in the presence of concerned Assistant Executive Engineer, Assistant Engineer, as per the order from the District Collector, Idukki and Executive Engineer Dam in charge. The first warning level of dam is at 40.70 m, second warning level is at 41.00 m and third warning level is at 41.30 m. The opening of shutters at each warning level will be informed to the concerned authorities. Due to small storage capacity the three warning levels is attained at very short intervals. Total numbers of shutters are six and will be opened in the order as shown below. The 4th shutter will be opened first, followed by 3rd shutter, followed by 5th shutter followed by 2nd, 6th and 1st from left abutment facing downstream. The spillway rating curve is at Enclosure – V. 4.3 Reservoir Sedimentation Review
As per record no survey has been carried out for present day capacity of the reservoir. Currently report furnished by the Executive shows that, the dead storage and live storage of the reservoir, are 10 Mm3& 27 Mm3respectively. Fresh survey shall be carried out to know the present capacity. The revised area capacity curve may be used for operation and other technical requirements. 4.4 Water Quality Aspects
Quality of water is normally good as per the record. Water testing results enclosed as Enclosure VI.
5. ISSUES IN DAM AND APPURTENANT STRUCTURES
a) On the earth dam downstream slopes and berms, huge material in the form of heaps was lying and huge vegetation has grown on it. Upstream embankment slope also has
157 vegetation with deep roots. This needs to be removed and dam section restored with properly compacted soil and pitching. b) In the earth dam downstream toe drain area it was reported that some sound of water falling is heard below the rock toe. During inspection at one location where stones had been removed it was noticed that seepage water from the filters is going below the toe drain. The main reason for this is that the level of toe drain is higher than the bottom elevation of rock toe. No seepage water was coming into the toe drain. All the seepage water travels below the toe drain and ultimately discharges into the downstream channel through the left training wall. It was mentioned that no particle are noticed in the seepage water. Nowhere seepage water was seen except the out let where few pipes have been provided. It is suggested that a sump at suitable location shall be constructed and seepage water shall be measured. c) The Dam was inspected on 5th July, 2019 with water level of 39.9m. Very few design drawings were available for review. It was informed that since the dam was constructed long back hardly any information on the design, drawings, geology or other information is available. The revised design flood and revised seismic parameters have to be got approved from CWC. Once the revised hydrology, design flood and seismic parameters are finalised, all the designs will have to be checked and required modifications made. If required suitable measures may have to be taken to ensure the structural safety and stability of the dam. The present observations given below are mainly visual observations with limited data and designs supplied to the DSRP. d) Design flood needs to be got approved at an early date to finalise further remedial actions. Remedial measures such as raising of earth dam, installation of solid parapet wall or other measures could have to be thought of. If the same spillway arrangement is to be used, the discharge intensity will be considerably increased and the energy dissipation arrangement may have to be checked / modified. This would be major problem and involve major remedial work. e) Stability analysis for earth dam and masonry dam be carried out considering Seismic parameters as per BIS 1893 and revised MWL and tail water. f) No tail water curve (TWC) is available as per present condition of the downstream channel. Lot of changes might have taken place in the downstream channel since commissioning of the project and earlier Even the TWC prepared at the time of construction may not be valid today and more over must have been prepared for a
158 lower discharge. Tail water rating curve needs to be prepared for the final approval of the revised design discharge.
6. MASONRY DAM AND SPILLWAY
6.1 Exterior Surface of Dam
a) Under DRIP I, vertical drainage holes were cleaned and new drainage holes were drilled. Vertical drains as seen from the top of masonry dam were clean and clear of any hindrance. b) Honey combing was seen on the side of the piers and vegetation at some places. c) In the downstream right bank area around penstock, heavy water logging was seen due to leakage. The water logging keeps the non-overflow area saturated and weakens the dam material. Due to water logging heavy growth of vegetation like jungle has come up. The water logging source shall be plugged and all water logging should be removed along with jungle.
6.2 Drainage Gallery
The dam has been provided with one foundation gallery, which was inspected and the observations are made as under a) It was informed that under DRIP I, grouting has been carried out in the Masonry dam in three rows from the top as heavy seepage was taking place in the gallery and wet- ness on the downstream face. It is reported that the seepage has reduced by 65% after grouting. During inspection it was observed that still seepage is taking place from the interface of the earth dam and left non over flow block. The only V notch installed in the gallery covers only about 20 m length of the non over flow dam and interface seepage. Though it was informed that the seepage in other parts is also reduced as observed by project Engineers after grouting, it is equally important to measure the seepage in rest of the dam. The interface area should be monitored for the seepage for turbidity. If the seepage water is found turbid, necessary remedial measures may be initiated to check the seepage. Very less seepage was observed in right side of the gravity dam in block No. 7 onwards. b) In the entire gallery from block 2 to 6 and in the adit seepage was seen from the reamed drains as well as from the gallery walls downstream & upstream and roof. Heavy leaching is also taking place and it was informed that they have to remove this
159 leaching every four months. This will weaken the masonry. To take care of this, first the seepage shall be further reduced. Additional grouting from the top of dam needs to be carried out. For this immediately V notches to measure seepage in the different sections of the gallery shall be installed. Initially the grouting shall be carried out in 2 blocks and effect on the seepage quantity reduced shall be observed to decide the spacing and pattern of grouting. c) In the gallery, seepage was also taking place from block joints and construction lift joints. The upstream face of the dam or the area between upstream face and gallery is the most venerable area. Earlier guniting with wire mash and other treatments have been suggested and some work was done in 2015-16. The treatment from upstream face is difficult and for it water level has to be brought down substantially low. This effects power generation. One row of chemical grouting with addition of quick setting adhesives can be used for grouting the upstream face at close spacing and at low pressure. During grouting operations a close watch from the reservoir side shall be made to observe any leakages. The help of divers or under water videography can also be taken. d) Foundation drains have been provided close to the upstream face in the gallery. Most of the drains were chocked and very less water was oozing out from few of these drains. These drains need to be re-drilled to release uplift pressure. If heavy seepage is noticed from these drains after drilling it is suggested that these drains after drilling shall be grouted and new holes drilled close to downstream face of gallery to release uplift seepage pressure. This will be more important when we considered the revised design flood which will increase the MWL close to the top of dam. The stresses in the gravity dam at foundation with revised MWL and revised seismic loading will increase substantially. Proper functioning of the drains will reduce the stresses at the foundation level.
6.3 Spillway Crest & Energy Dissipation Arrangements
a) Vegetation and spaling, erosion of material from the glacis seen. This work was included in DRIP-I but could not be completed due to non-availability of good contractor for this short work. It is to mention that this type of work is also required in other dams ie. Neyyar, Kallada, and Pamba. State Govt. may be facing this type of problem in other dams also. It is suggested to club all the projects and call for tenders. This is a specialised work and shall be done by a good experienced agency.
160 b) The stilling basin was full of water on the day of the visit. The stilling basin needs to be dewatered and inspected for erosions and damages. Sediments deposited in the stilling basin should also be removed to inspect the stilling basin. The extent of scour in the downstream pool needs to be surveyed and its tendency to retrograde and undermine the bucket needs to be examined. c) Downstream left training wall / river training works were carried out under the DRIP –I. The works carried out were in good condition. d) In the spillway downstream area few residential buildings were seen on the left side. The level of these buildings is below the downstream water level and likely to get submerged. Also there are security issues if they continue to be in the dam area. These need to be shifted to the place away from the dam complex area.
7. HYDROMECHANICAL ITEMS
The existing condition of Hydro-Mechanical works were reviewed in terms of their physical state, performance quality, functional deficiencies, structural weakness and the necessary integrity tests for establishing the structural soundness.
Following points are proposed: -
a) There structural members of the gates do not match with the members shown in the drawing, It is recommended to check the designs and drawings and if required strengthening of gates may be carried out.
Photo 1 Showing insufficient angular stiffeners as per approved drawings
161
Photo 2 Vegetation growing on Girder / arms of radial gates b) Since the radial gates were Installed / commissioned in the year 1994, and have served 25 years, all structural parts of gates should be sand blasted and then if required extra strengthening of Arms / Horizontal girders, Skin plate T girders, welding & grinding should be done. Wherever welding deposits are rusted and corroded then painting with coal tar epoxy is to be arranged to regain its life and strength. The servicing of Hydro Mechanical parts is maintained and found satisfactory. Further it is suggested to follow the points mentioned below in addition to regular maintenance being followed. i. All Horizontal Girders and Arms are to be cleaned properly before monsoon to avoid the continuous storage of water / forest waste/ mud/ vegetation. Due to this, structural parts get more corrosion and its strength will also decrease resulting in ageing of gates at an early time. Drain holes are to be arranged where ever required. Blocked drain holes are to be cleaned.
Photo 3 Showing radial gate condition.
162 ii. The upstream and downstream structural parts and skin plates should be sand blasted and all welds should be inspected, if required go NDT inspection and all weld should be built up grinded and painting. This should be done every4-5 years once. iii. a) Servicing of Lubrication is found satisfactory. b) There is no stock of spare and tools and tackles. c) No Trained man power / operators are available at site. e) There is no historical data on maintenance. However there are some original construction drawings available. There are deficiencies in servicing, maintenance and operational skills, noted during inspection. There is a need for training requirements for regular maintenance and keeping check list, break down maintenance record, preventive maintenance record, essential spare planning / its availability for immediate procurement, replacement is required and safety of operation and security of Gates operation. f) There is no requirement of stoplogs.
Photo 4 Reduction gear box and motor attached to hoist system of radial shutters
163 8. INSTRUMENTATION
a) Instrumentation: No instrumentation has been in place in the earth dam, Gravity dam and the spillway except V notch in the extreme left part of the gallery. i. For the spillway gallery, arrangements should be made to measure pressures in selected foundation drain holes from time to time and measurement of seepage emerging from them. ii. In order to facilitate informed decision on operation of the spillway, a weather station should be installed at the dam site and a few rain gauges in the catchment area for providing real time information about the likely inflows into the reservoir during the monsoon and cyclone seasons. An inflow/ flood forecasting system may be developed so as to provide inputs to all the projects in series and around. iii. V-notches in the gallery drain at suitable locations be installed so that total seepage is measured for each section of dam. iv. Surface settlement markers on the dam top to measure the settlement. v. Instruments such as Surface settlement targets, Piezometers, accelerographs, joint meters, & gauge points may be installed. Record shall be maintained for all the data. All instrumentation data shall be analyzed regularly. b) Centralized Control: The dam does not have a centralized control room at the top of the dam. For centralized operation of the gates and to maintain surveillance on the dam top, a control room along with the generator should be provided on any one end of the spillway with sufficient height to make visual observation of the entire dam top.
9. RECOMMENDED INVESTIGATIONS
1) Geological and geotechnical investigations a) Seismic Review: The height of Malankara Dam is 23m, therefore comes under large dam category as per NCSDP guidelines. Malankara Dam was inspected on 29.09.2013 by Dam Safety Review Panel constituted by Kerala Government. The committee recommended that design adequacy based on the seismic coefficient corresponding to Seismic Zone III should be checked for dam structural safety. While reviewing the reply to DSRP, it was noticed that seismic factor of 0.05 is taken for
164 design of dam profile considering Seismic Zone IV and dam is safe. However, it may
be mentioned that dam area falls in Zone-III and the horizontal seismic coefficient αh with a value of 0.12 should be used for stability analysis of dam in seismic conditions. No instruments for seismic monitoring were recommended by the panel. As the dam is already constructed, initially the following recommendations are made: i) Dam lies in Seismic Zone III. Stability analysis of the dam should be checked
considering the seismic coefficient (αh = 0.12) for Zone-III. After conducting the stability analysis, results should be submitted to DSRP for further evaluation. ii) This project is lying about 25 km from Idukki dam where a seismic network is under operation for the last several decades and it is therefore suggested that data collected by network should be obtained which will be helpful in understanding seismicity of the project area. iii) Peak ground acceleration is a very important parameter for assessment of earthquake effects on a structure. Accordingly, three accelerographs one at dam top, one in gallery and one in free field area should be installed. The free field accelerograph should be installed at a distance of at least 100m away (preferably in the upstream area) of barrage site. Each accelerograph having GPS facility and online data transfer capability should work as standalone system. iv) Proper space and installation is also very important for proper functionality of the accelerograph. It is therefore suggested that each accelerographs should be installed in a small room having proper protection from moisture. b) Material properties: No past records are available regarding material properties of the masonry as well as earth dams. Since only the Maximum water level of the dam is going to be higher the normal loading conditions i.e. FRL condition will not have any effect. As far MWL condition is concerned as long as water is below the top of the dam some modifications like raising the clay core, providing solid parapet wall etc. will be required for earth dam. The earth dam has no stability issues, therefore investigation for earth dam material properties is not required at this stage. For Masonry dam material properties will be an issue because stresses are going to be increased.
Another factor is the increased seismic coefficient based on latest BIS 1893 code provisions. Once the revised stability analysis in seismic condition is carried out, the need
165 for material properties of masonry and earth dam will be looked into based on final stresses for all loading conditions.
10. NON-STRUCTURAL MEASURES
Dam break analysis carried out by CWC and Emergency Action Plan as per the guidelines was prepared and got approved by CWC. The coordination mechanisms with disaster management authorities are established. Inflow forecasting/ flood forecasting system may be developed.
11. OPERATION & MAINTENANCE MANUAL
Project authorities informed that Operation and Maintenance Manual is preparedas per the guidelines for preparing O&M manual for the dam by CWC and submitted for approval.
Annual O& M Expenditure: -
Sl.No Year Expenditure (in Lakhs) 1 2015‐2016 3.12 2 2016‐2017 60.35 3 2017‐2018 44.75 4 2018‐2019 32.56
Present Establishment Set-up For O & M of dam
ORGANIZATIONAL CHART
Malankara DamDam
Executive Engineer
Assistant Executive Engineer
Assistant Engineer
166 Overseer Grade II- 2Nos
Overseer Grade III- 3 Nos
Lascar-5 Nos
SLR Workers (Working arrangement from MVIP Mechanical subdivision, Thodupuzha)- 4 Nos
12. SECURITY ARRANGMENT FOR DAM AND DAM APPURTNENTENANCE
Alternative route for public should be developed d/s of the project and the public thoroughfare on dam top should be avoided. Public movement has to be minimized / arrested. Security arrangement has to be made after taking appropriate action. The residential buildings in the downstream area coming in the flood prone area shall be shifted
13. BASIC DAM FACILITIES
a) Lighting arrangements have been done on dam top and gallery under DRIP –I package. Hand rails shall be provided in the galley. The dam top lighting shall be kept functional especially during the monsoon season by standby power in view of power failures at the site. b) There is no control room or shed on the top of the dam. The same should be provided for surveillance and emergencies. Also Watch Towers at any one end of the dam may be provided. Police aid post and control room is provided at dam. c) Adequate maintenance persons posted who are trained for the upkeep of dam & appurtenant structures.. d) Emergency power supplies by proving Generator is done for safe operation of the gates in all weather conditions. e) Pre and post monsoon inspections are done by department officials and KDSA. It is suggested that the State engineers shall be specially trained for carrying out
167 inspections. Govt. is arranging special training for state engineers as part of Institutional strengthening and to handle the Dam safety issues. f) All bays should be properly numbered and labels regarding hoists and gates should be provided. In the gallery also block numbers, levels instrumentation details etc. shall also be indicated. The earth dam shall be marked with RD’s g) Salient water levels observed in the past may be marked for proper reference in future. h) Lightening arresters to be provided.
14. SOURCE OF SECONDARY REVENUE GENERATION
Tourism - Malankara Reservoir is an artificial lake, spread over an area of 153.50 square km, formed as a part of Muvattupuzha Valley Irrigation Project. It is located in Idukki District, on the Thodupuzha – Moolamattom road. Malankara is at a distance of 66 kms from Cochin City and 7 kms from Thodupuzha, which is the gateway to top tourist destinations like Munnar, Vagamon, Thekkadi, Idukki Dam, Peermade, Elaveezhapoonchira, Thommankuthu waterfalls etc. The proximity of these destinations will synergize the tourism potential of Malankara. Malankara Reservoir provides a calm and charming atmosphere with the greenery in the surroundings. The place is ideal for nature lovers. The reservoir area could combine the elements of tourism and natural beauty. Tourism by developing around/ along the Reservoir of Malankara Dam, mainly using the marginal land and Islands of the Reservoir is an income generation plan. There are about 135 hectors of land above the full Reservoir level of the project. Malankara dam and reservoir area is one of the most beautiful environments in the central Kerala which does have four different climatic experience during the year. The location is ideal for tourism in winter, summer, and rainy seasons.
15. RECOMMENDATIONS
i. The distresses noticed should be carefully monitored till permanent measures are evolved and put in place. ii. Civil and Hydro mechanical built up drawings shall be prepared from the existing field information and various documents & reports available. iii. Jungle clearance works have to be carried out properly at U/s and D/s of the dam area, spill way area and earth dam area by removing bushes / vegetation / tress.
168 iv. Spillway glacis where ever damaged, shall be repaired after removing the vegetation with its roots. v. The design flood may be revised and got approved as per Central Water Commission guidelines. vi. Latest area capacity curve and tail water rating curve shall be prepared after latest survey. The Reservoir routing using the latest capacity curve and tail water rating curve should be carried out and the freeboard checked. vii. The site specific seismic parameters for evaluating the safety of the dam be evaluated and stability analysis may be carried out considering revised MWL and tail water. viii. The formed drains shall be re-drilled or additional new holes shall be drilled in between old drain holes for release of seepage water. In the gallery deposited calcium / calcinations shall be removed. The chemical analysis of the seepage water in the gallery shall be carried out. ix. Vertical uplift pressure holes have to be re-drilled. x. The pumping from the foundation gallery shall be carried out regularly and at short interval. xi. The stilling basin needs to be dewatered and inspected for erosions and damages. The extent of scour in the downstream pool needs to be surveyed and its tendency to retrograde and undermine the stilling basin needs to be examined. xii. The design of the entire energy dissipation arrangements shall be checked with the revised parameters (design flood, MWL, Tail water etc.) for comprehensive safety assurance. xiii. To arrest the seepage from the abutment proper investigation shall be carried out and if required grouting of the area shall be done. xiv. In the earth dams, bushes need to be removed with roots and dam slope where huge deposition has taken place shall be restored to desired slope along with pitching with proper compaction. xv. In the earth dam, downstream toe drain area where water is oozing in the toe drain area, it is suggested that a sump at suitable location shall be constructed and seepage water shall be measured. xvi. If the water level of reservoir is increased (i) it is essential to check the strength of gates and its embedded anchorages for having adequate safety margin. (ii) The clearance of bottom of gate in fully raised position, clearance of trunnion from water profile and that of the trunnion shall be checked as per guidelines.
169 i) All radial gate structural stiffener angles/ bearing plates are not provided as per approved drawing. It is recommended to check the original drawings and designs and arrange the angles and bearings in gate structures. It is also proposed that if required, extra angle stiffeners along with original drawings be provided to get more strength regain. ii) The yoke girder structural plates are found weak due to rust/ ageing. It is proposed to do sand blasting. It is found top & bottom plates of yoke girder are very much damaged. These are to be removed and replaced with new plates and rebuild the welding and do DA test (weld test). iii) In all radial gate, H Girders are to be cleaned before monsoon every year to avoid deposit of waste/ water/ mud, else the H- Girders will loses strength and gates will be aged early. iv) These gates are having lifting arrangements in the upstream side. It is recommended to inspect the gate lifting arrangements of the dam. All weld joints are to be checked properly, if required, rebuild the welds and greasing is to be done. v) The awareness programmes are to be arranged to mechanical engineers for maintenance and safety of dam project and its operation, maintain schedule break down and preventive maintenance charts/ program. xvii. Rehabilitate the embedded parts of the side seal seats and bottom sill seats. In any case they need to be cleaned thoroughly as they may damage the rubber seals fixed on the gates by rubbing. xviii. It appears that the dam is not connected in real time with any centralized control room during the monsoon period. If such arrangements are not in position, the same should be implemented. xix. All data collected from the instruments installed should be analyzed regularly to assess the health and performance of the dam. xx. Inflow forecasting shall be explored and put in place. xxi. Water quality tests for reservoirs and water both physical and chemical parameters are to be carried out at regular intervals preferably monthly.
170 ENCLOSURES
171 ENCLOSURE I (A)
172 173 ENCLOSURE I (B)
174 175 ENCLOSURE 2
LIST OF OFFICERS OF STATE GOVT. WHO ACCOMPANIED THE DSRP TEAM
1. P G Harikumar, Director, IDRB 2. Jaya P Nair, Superintending Engineer Project Circle, Muvattupuzha 3. Muhammed Basheer, Joint Director, Dam Safety, IDRB 4. C S Sinosh, Executive Engineer, MVIP Division No III, Muvattupuzha 5. Sabarinath C L, Assistant Engineer, MVIP Section 4/1, Muttom 6. R Ajithkumar, Assistant Executive Engineer, MVIP Mechanical Sub Division, Thodupuzha 7. Shabu Roy, Assistant Director, Dam Safety, IDRB 8. Bindu L, Assistant Director, Dam Safety, IDRB 9. Deepa K S, Assistant Director, Dam Safety, IDRB 10. K Suresh kumar, Assistant Engineer, MVIP Mechanical Section, Thodupuzha 11. Biju Samuel, Assistant Engineer, MVIP Electrical Section, Muvattupuzha 12. Deepa C, Assistant Engineer, MVIP Section 2/1, Muttom 13. Siby Thomas, Assistant Engineer, MVIP Section, 1/1, Muttom
176 ENCLOSURE III
Section-I Introduction
Following members of DSRP assembled at Malankara dam site
Sri.R.C.Jha Chairman Sri.S.R Toley Member Sri.M.K.Parameswaran Nair Member Sri.B.M.Upadhyay Member Sri.G.Rajagopalan Member Smt.A.Komalavalli Amma Member
As programmed the project has been inspected on 29.9.2013 The document
presented to the panel, prior to inspection ,included the details of the project,
findings of the previous inspection carried out by the department and proposals for
safety measures and improvement. The panel kept in view the presented
information while preparing the report. Except for the design flood there are no
issues of immediate concern as regards to the structural safety. This report of
DSRP reviews the structural deficiencies and safety and recommends action to be
taken on safety related issues. Topics covered are Hydrology, Geology and Dam
and appurtenant works:-Design and Construction.
List of officers is appended.
The report was submitted to the Irrigation Department through Chief Engineer,
IDRB.
177 MALANKARA DAM
MUVATTUPUZHA VALLEY IRRIGATION PROJECT
DAM SAFETY REVIEW PANEL VISIT Report as on 03-10-2013 MVIP Division No: III Muvattupuzha
178 1.0 INTRODUCTION
Second visit of DSRP was organized to inspect the dams in Idukki district ,from 28th September 2013 to 5th October 2013. After inspecting the dams under Kerala State Electricity Board ,DSRP inspected Malankara Dam under Irrigation Department on 3rd October 2013 .The documents presented include general information of the project , reports of previous inspections by the Department and the issues on which the DSRP’s view need to be sought. The panel kept in view the above while formulating the report.
Except for many fold increase in design flood and related studies, there are no major issues of immediate concern ,as regards the structural safety.
GENERAL
The Moovattupuzha Valley Irrigation Project comprises of an earth-cum-masonry dam at Malankara across Thodupuzha River, one of the tributaries of the Moovattupuzha River, a Right Bank Canal and a Left Bank Canal with their distributaries and minors to irrigate an area of 17737 ha.
The head work at Malankara consists of a composite earth-cum-masonry dam of total length 460 m and is 23 m high from the deepest river bed. The dam is divided into 12 blocks. The block of 206 m on the left flank is an earth dam. The remaining blocks form a masonry dam of gravity type. 6 spillway gates are located in blocks IV, V, VI & VII. The Left Bank head sluice is located in Block I and Right Bank sluice in Block IX. The gross storage at MWL is 42 Mm3 and at FRL 37 Mm3. The Right Bank canal has a length of 28.337 km with a gross command area of 5883 ha. It has only one branch namely Moovattupuzha Branch. This is a lined canal with carrying capacity of 9.378 cumecs at the point of off-take.
The Left Bank Canal has a length of 37.10 km with a gross command area of 15917 ha. It has 5 branches. This is fully lined with a carrying capacity of 24.207 cumecs at the point of off- take. The total length of branch canals is 58.50 km and that of distributaries 184 km.
179 Section-2
Salient Features:
1. Name of project : Malankara Dam
2. Purpose of project : Power / Irrigation
3. State : Kerala
4. District : Idukki
5. Latitude : Between 90 37 and 100 4’ N
6. Longitude : Between 760 26’ and 760 49’ E
7. Name of River : Thodupuzha (Tribotory of
Moovattupuzha River)
8. Type of Dam : Earth-cum-Masonry
9. Year of completion : 1994
10. Maximum water level : +43.00 m
11. Full Reservoir Level : +42.00 m
12. Minimum Draw Down Level : +39.00 m
13. Dead storage capacity : 27 Mm3
14. Gross storage capacity : 42 Mm3
15. Maximum height of dam : Masonry 23 m, Earth 12 m
16. Catchment area of dam : 153.5 Sq km
17. Probable Maximum Flood : 1444.32 cumecs (Reassessed
as 2316 cumecs)
18. Water spread area : 17737 ha
19. Dam length : Masonry 254 m, Earth 206 m
20. Top width of dam : Masonry5.00 m, Eartg 6.90 m
180 21. Bottom width : 16.70 m ( for masonry dam)
22. Design capacity of spillway : 1442.30 cumec
23. Crest level of spillway : +36.90 m
24. Number, type & size of spillway gates : 6 Nos. Radial 7.60 m x 6.40 m
25. Top of dam : + 45.00 m
26. Free board above MWL : 2.00 m.
27. Deepest foundation level +22.00 m
Section-3
1.0 HYDROLOGY
2.0 Hydrology criteria for safety of the dam.
Malankara Dam is located in Thodupuzha River. It is a straight gravity dam having a total length of 420 m including 206 m of earthen dam. The catchment area at the dam site is 153.50 km2. The top level of the dam is +45 m, MWL 43 m and FRL 42 m. The gross storage of the dam is 42 mm3. The water spread area of the reservoir is 22 km2. The height of the dam from the deepest foundation is reported as 23 m. As per BIS -11223, the dam falls in the category of ‘intermediate dam’ and therefore qualifies for SPF (Standard Project Flood) as design flood.
2.1 Design flood studies carried out by the Department.
It is reported that the design flood of the dam is 1442.30 cumecs and the spillway capacity has been designed to accommodate this flood. A note on hydrological review of dam has been made available to DSRP. According to this report the SPF has been computed as 2963 m3/s. It is mentioned in the note that the one day observed point rainfall of 660 mm at Perumbavoor has been adopted as candidate rainfall for computing Standard Project Storm (SPS). This value has the concurrence of CWC. The details of the studies and routing of inflow hydrograph are not mentioned in the note. It is seen that the maximum water level after routing reaches 48.01 m, which is about 3.01 m above the top of the dam.
181 2.2 Observations
The SPF studies carried out are based on the candidate storm suggested by CWC. The SPF with a peak value of 2963 cumecs appears to be reasonable. However this value exceeds the existing design flood of 1442.30 m3/s by 105%, which is alarming. During the course of discussions, the project officers have informed the members of DSRP that IMD has been approached for the revised SPS value. The project authorities have to expedite the revised SPF studies on top priority basis.
2.3 Recommendations.
a) The studies carried out so far indicate that an SPF value of 2963 cumecs appears to be reasonable and may be adopted for taking necessary measures for the safety of the dam. b) The DSRP recommends that immediate action may be taken for the preparation of an Emergency Action Plan (EAP) for the project by the project authority.
3 GEOLOGY
The project area forms a part of the Southern granulitic terrain belonging to the Archaean age. Blanded gneisses, mica schists, charnockites and intrusive granites occur in the area.
3.1Observations
At the dam site where the composite dam is constructed, the river bed is wide almost as in a plain country with the hill slopes raising with low angles. Fresh and massive exposures of gneissic rock are exposed in the river bed. While the flanks on either side are occupied by soil, scree and laterite.
Masonry portion of the dam is founded over the gneissic rock and transition provided to join with the earth dam. Details of the foundation grade and geology of earthen dam stretch are not available to ascertain the foundation characters of the medium over which the earthen structure is made. However based on the observations, primafacie the bed rock is not likely to be available at a higher level than the present river bed level at the left earthen dam area for providing additional spill way arrangements and the same need confirmation.
182 The area falls in seismic zone III of the seismic zoning map of India. Based on the isoseismal map prepared based on the felt intensity due to the Coimbatore earth quake of 1900 suggest that the area falls in zone V/VI of damage intensity scale.
3.2 Recommendations
The design adequacy based on the seismic coefficient as per the BIS code has to be checked for the dam structural safety.
4. 0 DAMS AND APARTMENT WORKS:DESIGN AND CONSTRUCTION.
The dam was inspected on 03.10.2013 FN. Water level on the reservoir was at 11.00 am is 38.83 m.
4.1 Observations
For the designed flood values mentioned above, the routing studies have been carried out by the Irrigation Department. The studies indicate that the water level will go above the dam top level. Therefore the present spillway is inadequate for tackling the design flood. The rise in water level is so high that the conventional method of raising the dam height etc. to accommodate the flood cannot be adopted here. Further the augmentation of capacity by increasing the length has to be ruled out from geological and construction considerations. Power production will get affected. There is no suitable site on the reservoir fringe to locate additional spillway vents or breaching section. Other unconventional alternatives are therefore need to be studied.
Thick vegetation growth was noticed on the upstream and downstream slopes of the embankment. The top road has a concrete topping, Stone pitching was observed on u/s and d/s slopes, no disturbances were noticed on the slopes. The surface drains on the d/s slope were clean. Stagnant water was seen in the drain. The general condition of embankment was satisfactory. The quality of masonry / concrete work in spillway, piers and non overflow section was not satisfactory. Pitting, scouring and honey combing were noticed on concrete of spillway glacis and piers. Such defects in the second stage concrete of wall plates of spillway gates are causing leakage jets through the piers. Similar defects causing heavy leakage in the gallery through the block joints and side walls of gallery were also noticed.
183 The gates of spillway were partially open. The energy dissipation arrangement was full of water and could not be examined. However it was reported by the project officers that the the arrangement is functioning trouble free.
The river section, immediately d/s of stilling basin had widened more than its normal section. The platform adjacent to the left training wall of spillway which serves as an approach to the gallery adit and where the wrap around slope terminates, gets protected by the earthen wall. However beyond this, the left bank is protected by pitching, which was noticed to be disturbed. Strengthening of this stretch is necessary.
4.2 Recommendations
The embankment dam should be allowed to overtop during the occurrence of flood by taking following precautions.
- The central impervious core should be raised up to top of dam level to avoid flow through the dam body. - Dismantle the parapet wall. Some waves may splash over the top. - Strengthen and extend the top road concrete slab to cover some length of u/s slope. - D/s stream slope should be protected by concrete cover in steps to form cascades for energy dissipation in the event of overflow. - Suitable toe protection is necessary and has to be provided. - Length of such provision could be decided after conducting flood routing studies.
Vegetation on embankment slopes, masonry structures and in the vicinity should be removed. The defects in concrete surfaces in ogee, glacis, piers, contraction joints and other places should be treated with epoxy grout /epoxy mortar/epoxy concrete. Low pressure grouting of the dam body should be resorted to, to check the seepage through dam body. Also the u/s face of masonry dam should be gunited in two layers with wire mesh sandwiched in between. Alternatively, impervious geomembrane could be installed in place of guniting. Cost and ease in construction could decide the alternative to be adopted.\ In addition, action to prepare Dam break analysis and Emergency Action Plan (EAP) should be initiated. Stilling basin should be dewatered and treatment, if any, required in the concrete surface or the toe of end sill should be attended to. Drainage holes should be cleared periodically. Painting, greasing and oiling of gates and other mechanical equipments should be done periodically as was being done on the day of inspection. All measures should be taken to give aesthetic appearance to the dam and surrounding area.
184 Necessary security provisions should be made to check the entry of unauthorized persons. After finalizing the MWL, the upper nappe profile should be checked to ensure that it is not getting obstructed by gates in open position and trunions. Seepage through the earth dam should be critically observed for migration of soil particles if any, The quantity should also be measured and recorded periodically.
185 ACKNOWLEDGEMENT
DSRP expresses its thanks to sri. V.K.Mahanudevan, Chief Engineer IDRB, sri K.M Ismail Chief Engineer (Mechanical)and their staff for making the necessary arrangements for inspection of the dam and for supplying the technical inputs during inspection and discussions. Our special appreciation and thanks are to sri. M.A.Babu, Executive Engineer for the help he extended in the preparation of report.
(S.R.Toley) (A.Komalavally Amma) (G.Rajagopalan)
Member Member Member
(M.K.P Nair) (R.C. Jha) (B.M Upadhyya)
Member Chairman Member
186 Officers of Kerala Irrigation Department.
Sri. V.K.Mahanudevan, Chief Engineer ,IDRB, Thiruvanmthapuram.
Smt. S.K Girija, Director IDRB Thiruvanamthapuram.
Smt. Leena George.Joint Director IDRB Thuvananthapuram.
Sri. M.A.Babu Executive Engineer MVIP Division No.III Muvattupuzha.
Sri. Lal Jayakumar Deputy Director IDRB Thiruvanamthapuram.
Sri. M.N Ramesan AEE,MVIP Sub Division No.1 Muttom
Smt. Aswathy Assistant Director IDRB Thiruvanamthapuram.
Sri. V.Mohanan AE MVIP Section No.2/1 Muttom
187 ENCLOSURE IV SALIENT FEATURES OF MALANKARA DAM MOOVATTUPUZHA IRRIGATION PROJECT Tributary/River Thodupuzha/ Moovattupuzha Type of structure Earth cum Masonry dam Location Between Latitude 90 37’ &100 4 North Between Longitude 760 26’ & 760 49’ East Place situated Muttom Village/Taluk/District Muttom/Thodupuzha/Idukki Year of completion 1994 Classification Major Irrigation Project Length Masonry-204m Earthen-206m Width at top 5 m Maximum height fromfoundation 23 m Gross storage atFRL 37 Mm3 Live storage at FRL 10 Mm3 Dead storage at FRL 27 Mm3 Dam top level EL. 45 m Maximum water level EL. 43 m Full Reservoir Level EL. 42 m Minimum Draw down Level EL. 39 m(river sluice level) Catchment area 153.5 sq.km Water spread area at FRL 5.66 sq.km Probable Maximum flood (Standard Project Flood) 2963 cumecs(the design flood is being reviewed by CWC and the anticipated final value will be around 2542 cumecs) Spillway details: Shape Ogee Length 62.10 m Type, No& Size of gates Radial type 6 nos of size 7.6m*6.4m Capacity 1444.32 m3/sec Crest level EL. 36.9 m Sluices River sluice 2 nos of size 1.5m*2m Canal LBMC-37.1km RBMC-28.337km Utility Irrigation, Power generation& Water Supply to KWA Schemes, Industries supply Ayacut area 18173 ha Installed capacity for power 10.5 MW Reservoir level up to which power production is allowed EL. 36 m
During the discussion it was informed by project authorities, that the design flood is being reviewed by CWC and the anticipated final value will be around 2542 m3/s. With this the MWL achieved will be 44.63 with all gates open against top of dam as 45m. Efforts may be made to get the approved value of design flood from CWC considering the flood of 2018.
188 l ENCLOSURE V i \ :r---
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To be rectified to its geometric profile. Photos 11 & 12 indicate the distress condition of the parapet wall. To be repaired and colour wash has to be made. 195 Photos 13 to 16 indicate the spillway, pier and body wall of the dam. Algae/Bushes has to be removed. Photos 17 to 20 indicate the u/s & d/s face of the dam the joints to be repaired with PICC mortar. Leakage has to be rectified at the junction of abutment and spillway with PICC special mortar. 196 Photos 21 indicate the old ring bund (structure) at the u/s of the dam. Photos 22 to 23 indicate the u/s side rip-rap. The disturbed portion of rip-rap has to be re-laid and slope has to be reconditioned to its original profile. Photos 24 & 25 indicate bulged portion of the embankment. It should be realigned to its original profile with proper compaction. 197 Photos 26 & 27 indicate that there is no Hand rail provision in the gallery. Photos 28 to 31 indicate the calcium deposit at the gallery walls and at junction points with abutment. 198 Photos 32 & 33 indicate the chocked/unchecked vertical shaft holes. Top cover has to be provided. Photos 34 indicate that, there is no 35 indicate the improper maintenance collection well. Pumped directly from of V-Notch. the seepage channel. Photos Photos 36 indicate that, there is full Photos 37 indicate that, berms of the of water in the stilling basin. canal shall be rehabilitated. 199 Photos 38 & 39 indicate that, at the top the dam road there is no rain drain provision. To be provided. Photos 40 & 41 indicate the repaired condition of the hoisting arrangement platform. Photos 42 indicate that, the Photos 43 indicate that, lightning electrical junction box has not arrester and siren has to be provided in the gallery. It should be provided. Lighting arrangement has provided. to be improved in the dam premises. 200 18. REFERENCES 1. Bathymetric survey report 2. GO no 4/92/Ir D dated 11/02/1992 – IDRB Expert committee report 3. GO no 25/93/Ir D dated 09/07/1993 - IDRB Expert committee report 201 ANNEXURES 202 ANNEXURE I SCHEDULED DAM SAFETY INSPECTION FORM Part 1a - Inspection Details: Dam Name: MALANKARA Project ID Code (PIC): KL 07 MH 0049 Dam Type: Large Dam Dam Purpose: Irrigation Dam Owner: Executive Engineer, MVIP Division No.III, Hazard Classification: - Muvattupuzha Dam Operator: Do - Type of Inspection: DSRP. Commissioning Date: 1994 Inspection by: DSRP – Team City/State/PIN: Thodupuzha/ Kerala/685587 Date of Inspection: 05.07.2019 Reservoir water level in metre on the District: EL. 39.90 M Idukki date of inspection: (i) Gross 37.00 Mm3 Latitude: Storage Capacity Between 90 37’& 100 4 North (ii) Live 10.00 Mm3 Longitude: Between 760 26’& 760 49’ East Weather Conditions: Drizzling / Sun shine a) TBL RL. EL. 45.00 m b) MWL RL. EL. 43.00 m c) FRL RL. EL. 42.00 m Minimum : - Important Controlling Level d) Spillway Crest RL. EL. 36.90 m Temperature : Maximum :- e) MDDL RL. EL. 28.00 m f) Lowest River bed RL. EL. 25.00 m g) Deepest foundation level RL. EL. 18.00 m 203 Part 1b - Inspection Remarks: The background of DRIP works mainly araised from DSRP panel recommendations after visit on 03.10.2013 and from the tomographic study at Malankara dam by M/s Parsons Overseas Pvt Ltd. The Geographical investigation study for analysis of heavy seepage in Malankara Dam was conducted by M/s Parsons Overseas Pvt Ltd. and as per scope of work, electrical resistivity tomography (ERT) & streaming potential (SP) were envisaged as primarily tools of investigation to detect anomalous zones and seepage locations, to be carried out throughout the length of dams (Masonry & Earthen) These recommendations were included in the DRIP work estimate to arrest the leakage in earthen and masonry portion of Malankara Dam After grouting the seepage value has been considerably reduced to an extent of around 65% 204 Part 2a Inspection Checklist Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory A-Reservoir A-1.1 General Condition 1.1.1 Is the reservoir water level unusually high or low? N 39.90m on 5/7/2019 1.1.2 Are there signs of decline in water quality? N Water quality report enclosed. 1.1.3 Are there signs of recent sediment deposition? N No survey carried out 1.1.4 Is floating debris present? Y Debris around intake of Power and both canals Fair Any indications of major active or inactive landslide area in the 1.1.5 N Not seen on the day of visit immediate U/S reservoir rim? If so, indicate their locations and extent. Families/people in dam reservoir area needs to 1.1.6 Are there people or livestock in and around reservoir? Y be shifted. 1.1.7 Any other issues? N B-Dam and Dam Reach (Embankment) B-1.1 General Condition 1.1.1 Any major alterations or changes to the dam since the last inspection? N Some families who were residing at the time of 1.1.2 Is there any new nearby development in the downstream floodplain? N Fair construction are still there. 1.1.3 Any misalignment of poles, fencing or walls due to dam movement? N B-1.2 Upstream Slope Any signs of bulging or concavity (depressions)? If so, indicate their 1.2.1 locations and extent. (Check up the cross-sections with tape and level N Details in report. at random locations, at least two) Does the section of the dam and upstream slope appear structurally 1.2.2 Y Details in report. sound and stable? 205 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory 1.2.3 Presence of longitudinal or transverse cracks? N Details in report. Whether any signs of distress to stability of slopes noticed at any time in any part of the dam? If so, give brief details of the incidents and 1.2.4 N Details in report. location, the method of treatment adopted and its effectiveness. Fair Indicate the general condition of upstream pitching. 1.2.5 Any degradation to slope protection (rip-rap)? Y Details and suggested measures in report. Is there any profuse growth of bushes or weeds over any portion of 1.2.6 Y Details and suggested measures in report. the dam? If so, indicate the locations. Does the upstream slope shows existence of crab holes or holes made Prima facie not seen 1.2.7 by rodents or burrowing animals or ant hills? If so, indicate the N during visit locations. 1.2.8 Any other issues? B-1.3 Crest of Dam Is the crest profile at proper elevation? (To be test checked at random 1.3.1 Y locations by taking level) Does it show any signs of excessive and/or uneven settlement? If so, 1.3.2 indicate such locations and extent of settlement. (Surface settlement N As given in report points must be installed for observing this aspect) Is the surface of the crest free from undulations and local depressions 1.3.3 Y or heaving? 1.3.4 Does it provide an all-weather road surface? Y 1.3.5 Any degradation to access road (sealed/unsealed)? N Does it develop any visible cracks in transverse or longitudinal directions? If so, attach a map showing their locations and extent. 1.3.6 N Depth of cracks must be ascertained by taking open trenches extending below the bottom of cracks. What is the condition of the edges of the crest/ Have got eroded and 1.3.7 N cut up resulting in reduced effective width? Satisfactory 1.3.8 Is the crest free from local slips throughout its length on either sides? Y 206 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Do the headers, guard stones and parapet wall provided at the edges 1.3.9 Y of the crest appear in proper profile and plumb? 1.3.10 Any degradation to upstream parapet or downstream curb wall? N 1.3.11 Evidence of livestock on dam crest? N 1.3.12 Trees or profuse growth of weeds/bushes at any location? N 1.3.13 Proper lighting arrangement at dam top? Y 1.3.14 Any other issues? N B-1.4 Downstream Slope Material dumped on D/S slope. Details and 1.4.1 Any signs of bulging or concavity (depressions)? N remedial measures given in report Are there any wet or slushy patches or any concentrated leaks, springs Leakage in and around or trickles observed on the downstream slopes or the toe? If so, toe drain. To be 1.4.2 indicate their locations and extent. Please look out for patches of Y monitored. Details extensive vegetation growth and examine them carefully and record given in report. the findings. 1.4.3 Presence of longitudinal or transverse cracks? N 1.4.4 Any signs of distress to the stability of slopes? N 1.4.5 Are rain cuts/erosion channels present at any location? N Are all the rain cuts and erosion channels properly treated and made 1.4.6 NA good? Please indicate location of recurring damages, if any. Fair Is there any profuse growth of bushes or weeds over any portion of 1.4.7 Y Details in report the dam? If so, indicate the locations. Does the downstream slope show existence of crab holes or holes 1.4.8 made by rodents or burrowing animals or ant hills? If so, indicate the N Prima facie not seen during visit locations. 207 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Any other degradation to slope protection (turfing)? Indicate the 1.4.9 N general condition of downstream pitching/ turfing and rock toe. 1.4.10 Is the downstream area clear of debris and freely draining? Y 1.4.11 Any other issues? N B-1.5 Downstream Drainage Are there any signs of water logging, slushy conditions or growth of 1.5.1 aquatic weeds on the downstream of the dam? To be checked upto N 300 m downstream of toe Are there any standing pools of water in the downstream of dam? If No pool but habitation just after about 150 m 1.5.2 so, give their locations and extent. To be checked upto 300 m N downstream of dam. downstream of toe Are there any boils observed in the vicinity of the downstream toe of 1.5.3 N the dam? If so, give locations. 1.5.4 Is the downstream area sufficiently clear and freely draining? Y a) Max. Ground water level not measured What is the depth of ground water table on the downstream as b) Location - 100m apart from d/s of dam 1.5.5 evident from the existing wells in the vicinity of the dam? To be c) Date 05.07.2019 checked upto 300 m downstream of toe. d) Corresponding Reservoir level 39.90m Does the water table show any marked variation in accordance with 1.5.6 Y the variations in reservoir water level? Poor 1.5.7 Are all the exposed drains working satisfactorily? Y 1.5.8 Toe drains and cross drains: i. Are the portions of longitudinal toe drain and exposed cross Toe drain is higher than downstream earth. drains beyond the downstream toe of the dam in regular section and dam toe elevation. Details given in report freely draining? ii. Is the pitching to these drains intact? Y iii. Is there any weed growth in these drains? Y iv. Any other defects noticed in the drains?. N 1.5.9 Outfall Drain: (a) Is the outfall drain in proper shape and grade and freely 1.5.10 Y draining? 208 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory 1.5.11 (b) Is the outfall drain properly cleaned and maintained? Y Does the outfall drain show any stagnant pools of water or weed 1.5.12 N growth? B-1.6 Surface Drainage of Downstream Slope Is the condition of the downstream slope drainage 1.6.1 Y arrangements, if provided, satisfactory? 1.6.2 Is the paving to these drains intact? Y Are all the drains properly maintained and free of vegetation 1.6.3 Y growth and debris? Fair Material deposition on Does the slope have a tendency to develop severe rain cuts at any 1.6.4 Y the downstream slope can cause rain cuts. location? Enumerate any other defects noticed in the surface drainage of 1.6.5 N downstream slope B-1.7 Seepage Measurement Is the quantity of seepage being daily or periodically measured and 1.7.1 N recorded? Please check the registers and record observations. No seepage data being Does it show any abnormal rise or fall? If so, explain if it has any 1.7.2 N measured. relation to a certain reservoir level elevation. Does the seepage show a turbid colour at any stage? Was such a No seepage data being 1.7.3 phenomenon has been observed at any stage, at any location in the N measured. past. What is the measured rate of seepage flow with date and reservoir 1.7.4 level: No seepage data being Poor i. On the day of present inspection measured. ii. Maximum since last June iii. Minimum since last June Is the portion upstream and downstream of measuring points of No seepage data being 1.7.5 seepage easily accessible with proper steps and paths and free of Y measured. vegetation growth? Are the measuring points properly located, constructed and No seepage data being 1.7.6 maintained so as to give accurate and reliable measurements of NA measured. seepage in accordance with the relevant IS Codes? 209 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory 1.7.7 Is the method of taking seepage measurements satisfactory? NA Same as B 1.7.6 Breaching Section (if provided B-1.8 NO BREACHING SECTION NOT PROVIDED 1.8.1 Is the breaching section easily accessible? 1.8.2 Is the condition of the breaching section satisfactory? Is the note of instructions as to when and how to operate the 1.8.3 breaching section available on record? For reconstruction after the breach, are the following items decided 1.8.4 in advance? a) Quarry for embankment material b) Suitable routes of access Is the maintenance staff fully aware of the instructions related to 1.8.5 operation of the beaching section and for reconstruction after the breach ? Ascertain and indicate the latest event of operation of breaching 1.8.6 section and its performance. 1.8.7 Evidence of recent degradation? 1.8.8 Any other issues? Junction of Earth work with Masonry/Concrete dam sections B-1.9 and outlets Is there any existence of leaks, springs or wet spots in the earth work in the vicinity of the junctions between earth work and masonry Details and remedial action in report. 1.9.1 works? If so, what is the approximate rate and colour of the leakage/ Y does it turn turbid at any time?. Please ascertain from enquiries and record the findings. Is there any tendency for separations, cracking, settlement or 1.9.2 upheaval of the earth work in the vicinity of masonry or concrete? If N so, indicate the locations and the exact nature of deficiency. Poor Is there any tendency for surface erosion or slope instability at the 1.9.3 N junction? 210 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory If the outlet conduit is located in the earth dam section, is the entire length of the conduit in perfect order and profile and free from 1.9.4 offsets, open joints, cracks and leakage? Examine the conduit NA carefully from the downstream or from inside, if possible, and indicate the deficiencies observed, if any. 1.9.5 Any other issues? N Relief Wells B-1.10 NO RELIEF WELLS No relief Well 1.10.1 Are the relief wells in good working condition and functioning well? 1.10.2 Are the relief wells properly surged and cleaned periodically? Please indicate the dates of last surging and cleaning and the next 1.10.3 surging due. Are the necessary plant and equipment for cleaning the relief wells, 1.10.4 available with the office? Is the record of periodical measurements of discharge from each 1.10.5 relief well maintained? If so, indicate total discharge and maximum discharge observed from a single well on the date of inspection. B-1.11 Abutment Contacts 1.11.1 Any presence of leaks, springs or wet spots near the abutment? N 1.11.2 Any presence of cracking, settlement or upheaval of earthwork? N 1.11.3 Any evidence of erosion or slope instability? N 1.11.4 Trees or profuse growth of weeds/bushes? Y Satisfactory Any degradation to up/downstream slope protection (rip-rap, 1.11.5 N turfing)? 1.11.6 Any other issues? N C-1 Dam and Dam Block/Reach (Concrete/Masonry) C-1.1 General Condition 1.1.1 Any major alterations or changes to the dam since the last inspection? N 211 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory 1.Training wall constructed in D/S 1.1.2 Is there any new nearby development in the downstream floodplain? Y 2. Two trash racks provided Satisfactory 1.1.3 Any misalignment of poles, fencing or walls due to dam movement? N C-1.2 Upstream Face 1.2.1 Evidence of surface defects (honeycombing, staining, stratification)? - 1.2.2 Concrete/masonry deterioration (spalling, leaching, disintegration)? Y 1.2.3 Is cracking present (structural, thermal, along joints)? N Mostly area not visible as water level at 39.9m against FRL of 42m.Upstream face to be inspected .When water level goes down 1.2.4 Evidence of differential settlement (displaced/offset/open joints)? N Fair Under water videography can also be done 1.2.5 Presence of vegetation (growth in joints between blocks)? N 1.2.6 Evidence of any other damage to joints and/or water stops? N 1.2.7 Any other issues? C-1.3 Crest of Dam 1.3.1 Evidence of differential settlement (displaced/offset/open joints)? N 1.3.2 Presence of cracking (structural, thermal, along joints)? N 1.3.3 Profuse growth of weeds/grass/plants at any location? Y Fair 1.3.4 Any degradation to access road? N 1.3.5 Any degradation to upstream parapet or downstream curb wall? N 1.3.6 Any other issues? C-1.4 Downstream Face 1.4.1 Evidence of surface defects (honey-combing, staining, stratification)? N 212 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory 1.4.2 Concrete/masonry deterioration (spalling, leaching, disintegration)? N 1.4.3 Presence of cracking (structural, thermal, along joints)? N 1.4.4 Evidence of differential settlement (displaced/offset/open joints)? N Fair 1.4.5 Presence of vegetation (growth in joints between blocks)? N 1.4.6 Evidence of any other damage to joints and/or water stops? N Gallery joint leaking 1.4.7 Excessive seepage/sweating at any location on downstream face? N 1.4.8 Significant leakage at any location on downstream face? N 1.4.9 Any other issues? C-1.5 Abutment Contacts 1.5.1 Any presence of leaks, springs or wet spots in vicinity of abutment? N 1.5.2 Any presence of cracking or settlement? N Satisfactory 1.5.3 Profuse growth of weeds/grass/plants at any location? N 1.5.4 Any other issues? N D Gallery/Shaft and Drainage (Concrete/Masonry) D-1.1 General Condition 1.1.1 Slushy condition or water logging immediately downstream of dam? N Satisfactory 1.1.2 Any evidence of boiling in vicinity of dam toe? N D-1.2 Gallery/Shaft Condition 1.2.1 Any problems accessing or inspecting gallery/shaft (obstruction)? N 1.2.2 Any safety issues (inadequate handrails, lighting or ventilation)? Y No hand rails provided. Capacity of Sump well to be increased.Regular Problems of inadequate drainage (slippery stairs, water logging of 1.2.3 Y pumping at short interval. gallery, clogged porous or foundation drains)? 1.2.4 Evidence of differential settlement (displaced/offset/open joints)? N 213 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory 1.2.5 Excessive seepage/sweating at any location along gallery/shaft? Y Joints leaking as seen in Gallery. Details in report. Significant or excessive leakage at any location along gallery/shaft / 1.2.6 N Joints leaking as seen in Gallery. Details in report porous drain? If yes, provide location(s). Are proper arrangements made for the measurement of seepage into Only one V notch the gallery? Is the seepage measured separately from 1. Porous provided for measuring seepage of 20 m length of 1.2.7 pipes, 2.Foundation Y gallery. Additional V notches required drains and 3.Monolith Joints?Are the above arrangements satisfactory? Has there been substantial progressive reduction in the seepage 1.2.8 through the foundations? Indicate if it is due to choking of the drain N holes and if so, indicate the number of choked holes. Poor Are all the foundation and porous holes periodically cleaned with reaming tool and air water jetting? Indicate the last date of such 1.2.9 N cleaning and extent of variation observed in the seepage discharge before and after the cleaning. Is the seepage water and the deposit, if any, from the seepage being 1.2.10 regularly examined for chemical composition? If so, indicate the N result and the probable source of dissolved salts, if any. Are any seepage water springs observed in the downstream area any where? If so, indicate the locations and state the physical nature of 1.2.11 this seepage. Look out for such seepage spots particularly near the N dykes, fault zone etc. Ascertain if chemical testings are made of water samples from such springs for dissolved salts. 1.2.12 Is there any leachate deposition? If yes provide location Y 1.2.13 Any other issues? N D-1.3 Drain Condition 1.3.1 Is the flow in the drain unusually high or low? Not measured fully 1.3.2 Presence of calcium or other deposits in drain? Y 214 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory 1.3.3 Is the dewatering pumping station fully operational? Y 1.3.4 Any problem inspecting the pump? N 1.3.5 Any obstruction preventing or impairing smooth operation? N 1.3.6 Any deterioration of pump and associated equipment? N Poor 1.3.7 Is the sump well clean and maintained? Y 1.3.8 Is the V-notch before sump well cleaned and maintained? N No V notch before sump. Lot of calcination and Any other evidence of the drain being blocked/having reduced 1.3.9 N silt deposited. section? 1.3.10 Is the flow in the drain noticeably sporadic/irregular? N Not measured. Fully 1.3.11 Does the drainage water have unusual color (leachate)? Y Details in report 1.3.12 Any other issues? D-1.4 Body Wall (Masonry/Concrete) of ‘NOF’ Dam and Spillway What is the total seepage into gallery from the porous pipes in the 1.4.1 dam at lake full condition? Compare it with the seepage when the N Not measured. fully reservoir was first filled. (For the corresponding water level) If there has been substantial reduction in this seepage? Ascertain and Reduction in one left 1.4.2 Y indicate the probable reasons therefore. section after grouting - DRIP Phase-I work. Has there been a tendency for gradual reduction of drainage through Reduced after grouting 1.4.3 pipes and progressive appearance of sweating on the downstream Y As per DRIP phase -I face of the dam? Has there been considerable leaching from the seepage water and 1.4.4 Y Details in report deposition of lime near the seepage exit spots? Testing report Are the samples of the seepage water and reservoir water being 1.4.5 Y Enclosed in Annexure X. regularly tested for reactive and corrosive properties? Fair 215 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Is there excessive seepage, sweating at any locations on the downstream face of the dam? ( Examine the monolith or 1.4.6 N construction joints for such seepage and leaching and indicate the findings) Is there any swelling or cracking observed on the downstream face especially near the points of concentration of stresses like the toe or 1.4.7 N locations of abrupt change in geometry of the face of the opening? If so, indicate the details of observations. Mostly area not visible as water level was at Is the pointing on upstream face of the dam in good condition? If 1.4.8 Y 39.9m against FRL of 42m. not, indicate the nature and extent of deficiency. Are the registers and graphs showing the periodical measurements of 1.4.9 seepage discharge from the porous drains in the gallery and from the Y Graph for last 5 years enclosed downstream face at various lake levels maintained at site? D-1.5 Waste Weir Bar and Tail Channel NO WASTE WEIR/TAIL CHANNEL Is the Concrete/masonry spillway bar in good condition? Indicate if there is any leakage through the masonry or from the foundation. If 1.5.1 so, what remedial measures are proposed/taken for minimizing the NA leakage? Is the record of leakage measurement maintained? What is the quantity of Seepage/Leakage on the date of inspection? 1.5.2 Is the coping over the spillway bar in good condition? NA Does the upstream and downstream face of waste weir bar need 1.5.3 NA pointing? Is there any scouring on downstream side of the bar and/or EDA? If 1.5.4 NA so what remedial measures are proposed/taken? Are there any damages or undermining to guide walls, divide wall and 1.5.5 other appurtenants? If so, indicate what remedial measures are NA proposed/taken. Structural performance of the ‘NOF’ and ‘OF’ Portions of D-1.6 Dam Foundations Are there any signs of structural distress noticed in the dam spillway 1.6.1 and foundations in the form of- 216 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory i. Excessive deflection with respect to permissible deflection at NA the time of design No instrumentation provided to measure ii. Tendency of gradual sliding NA these parameters. iii. Cracking and upheaval or settlement in any part of the body Poor NA wall or foundations, iv. Excessive uplift, NA v. Excessive seepage and leaching through the body of the dam NA and the foundation. Conspicuous weathering of materials or components in any portion 1.6.2 N of the body wall or the foundations. E Spillway and Energy Dissipation Structure E 1.1 Spillway Any problems inspecting spillway (obstructed access, damaged 1.1.1 N catwalk)? 1.1.2 Any obstructions in or immediately downstream of the spillway? N Evidence of abrasion, cavitation or scour on glacis (e.g. exposed 1.1.3 N reinforcement)? 1.1.4 Presence of displaced, offset or open joints? N 1.1.5 Presence of cracking (structural, thermal, along joints)? N Fair 1.1.6 Evidence of surface defects (honeycombing, staining, stratification)? Y 1.1.7 Concrete/masonry deterioration (spalling, leaching, disintegration)? N 1.1.8 Presence of vegetation (growth in joints between blocks)? N 1.1.9 Evidence of any other damage to joints and/or waterstops? N 1.1.10 Excessive seepage/sweating at any location on spillway glacis? N 1.1.11 Significant leakage at any location on spillway glacis? N 1.1.12 Any other issues? N 217 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory E-1.2 Energy Dissipation Structure 1.2.1 Any problems inspecting energy dissipation structure? Y Dewatering is to be done to identify the problems Any obstructions in or immediately downstream of dissipation 1.2.2 N structure? 1.2.3 Evidence of abrasion, cavitation or scour on dissipation structure? NA Dewatering is to be done to identify the problems 1.2.4 Presence of displaced, offset or open joints? NA -do- 1.2.5 Presence of cracking (structural, thermal, along joints)? NA -do- 1.2.6 Evidence of surface defects (honeycombing, staining, stratification)? NA -do- 1.2.7 Concrete/masonry deterioration (spalling, leaching, disintegration)? NA -do- 1.2.8 Presence of vegetation (growth in joints between blocks)? N -do- 1.2.9 Evidence of any other damage to joints? NA -do- 1.2.10 Any problems with under-drainage (blockage of open drain holes)? NA -do- Can the tail pond be drained easily for inspection of the stilling basin or bucket? If not, indicate the alternatives available for dewatering. Proposal for dewatering to be submitted 1.2.11 Please ascertain and indicate the last event of inspection of stilling Fair basin (or bucket). From the examination of the levels and contour plans and reference marks in tail channel; is there progressive erosion and retrogression in Survey needs to be carried out in downstream tail 1.2.12 the tail channel? If so, indicate the extent and location of such erosion NA channel area to have and introgression about with reference to the various components of dam, spillway, outlet, erosion. power house etc. Is the concrete surface of the stilling basin and apron (or bucket) in good condition? Are there any indications of pitting, cracking, 1.2.13 NA spalling or wearing of the surface of bedding concrete? If so, please give details of the nature and extent of the damage. 218 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Is there any indication of abrasion and cavitation damage (pitting of concrete) especially at friction blocks , chute blocks and slotted 1.2.14 NA roller teeth, the surface near the lower tangent point and the end sill? If so, please give the details of nature and extent of damage. Is the under drainage of the stilling basin (or bucket) satisfactory? Are 1.2.15 NA all the open drain holes clear and functioning well? 1.2.16 Any other issues? F Intake/Outlet and Water Conveyance Structure F-1.1 Intake/Outlet Structure Any problems inspecting intake/outlet structure (obstructed/unsafe 1.1.1 N access)? Any obstructions in, upstream or downstream of intake/outlet 1.1.2 N structure? 1.1.3 Evidence of abrasion, cavitation or scour on intake/outlet structure? N Satisfactory Any evidence of structural distress (displaced/offset/open joints, 1.1.4 N cracking)? Any evidence of surface defects and/or concrete/masonry 1.1.5 N deterioration? 1.1.6 Any other issues? F-1.2 Water Conveyance Structure Any problems inspecting intake/outlet structure (obstructed/unsafe 1.2.1 access)? Any obstructions in, upstream or downstream of water conveyance 1.2.2 structure? 1.2.3 Evidence of abrasion, cavitation or scour on structure? N 219 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Any evidence of structural distress (displaced/offset/open joints, Fair 1.2.4 N cracking)? The PCC lined canals in some stretch is in 1.2.5 Any evidence of surface defects and/or material deterioration? Y damaged condition and requires revamping. Seepage in areas where bed lining is damaged 1.2.6 Any evidence of seepage or leakage from water conveyance structure? Y 1.2.7 Any other issues? N G-1 Hydro-Mechanical Component and Pump Spillway Gates (Radial gates, Vertical lift gates, Automatic G-1.1 gates) 1.1.1 Any problems inspecting gate/Stop-logs (obstructed/unsafe access)? N Is the condition of the steel surface and the surface paint 1.1.2 Y Recommended for sand blasting, painting deteriorated? Replacement of rubber seals of radial gates - work Are any connection bolts of rubber seals loosened or damaged? If so, 1.1.3 Y tendered indicate the details of defects. Replacement of rubber seals of radial gates - Do any of the rubber seals show signs of weathering, hardening, 1.1.4 Y work tendered cracking or tearing and damage? Are the rubber seals of side and bottom touching uniformly all along 1.1.5 N Same as G1.1.4 the sealing surface? Rollers are well lubricated. But some rollers don’t Do the rollers (wherever applicable) touch the track plates 1.1.6 Y touch the track plates uniformly uniformly? Are the rollers well lubricated? Are the embeded parts of spillway gates, emergency gates and stop- logs in sound condition and free from corrosion, uneven wear, 1.1.7 Y cracking, chipping and dents? If not, state the nature of defects or deficiencies and observation, if any, regarding such defects. Are the following members and welded, bolted and riveted connections structually sound? If not, please give details of any 1.1.8 uneven wear, uneven bearing, cracking, chipping and dents and indicate the findings: 220 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory (1) Gate leaf and stiffeners In good condition (2) End arms In good condition (3) Trunnion girders / Yoke girder In good condition (4) Stop logs NA (5) Lifting beams NA (6) Gantry cranes NA (7) Tracks In good condition (8) Trunnion bracket In good condition (9) Chains/ wire ropes In good condition (10) Bridge structure In good condition 1.1.9 Are the trunnion bearings of radial gates properly lubricated? Y Is there any damage or wear caused to the seal plates? If so, indicate 1.1.10 the nature of damage noticed. Are any of the mechanical or structural components and fastners or During sand blasting all the weld/bolt joints are to seals subjected to excessive wear? If so, please give details. Is there 1.1.11 N be inspected properly if required. any tendency for recurring damage to any particular component? If so, please give details. Is sufficient stock of spares which need frequent replacement Recommended strictly to maintain in essential 1.1.12 N maintained at the site? spares at site 221 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Works are arranged on need to need basis & no Any issues with storage of equipment (emergency stop logs, lifting 1.1.13 NA equipments stored at dam site as of now beam and gate leaves)? Any deterioration, corrosion? scaling? pitting? or cracking? of 1.1.14 NA equipment (connecting bolts, welds?) 1.1.15 Any obstructions preventing or impairing smooth operation? NA Any problems with the rollers (not touching tracks, inadequate Rollers are well lubricated. But some rollers don't 1.1.16 Y lubrification)? touch the track plates uniformly 1.1.17 Any debris, etc., in the gate grooves? Y Any damages to Radial Gate trunion pins? gate arms? lubrication? 1.1.18 N etc.? 1.1.19 Any damage to embedded parts above waterline? access structure? N 1.1.20 Any damage to concrete grooves? Y Is the staff posted at the site for maintenance and operation of gates, Existing staffs are only for shutter operation 1.1.21 hoists, equipments and electrical installations, well experienced, fully N purpose and not for maintenance. trained and conversant with the job requirements and responsibilities? Are the following documents maintained at the respective location of N all the units? (1) Maintenance schedules specifying each operation, its frequency 1.1.22 N Not maintained and ‘due’ and’ done’ dates. (2) Operating instructions with ‘dos’ and ‘don’t’ for all operational N Not maintained units. 1.1.23 Are the trunnion hub and the brackets well maintained? Y Are the trunnions likely to get submerged during actual working of Regularly ensure trunnion bracket anchorage/ 1.1.24 the spillway? if so, ascertain the causes for the same and specify. N connecting bolts with yoke girders. Please enquire for occurrence of such events, if any. 222 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Are all the nuts of connecting bolts and anchorages properly 1.1.25 Y tightened? 1.1.26 Any other issues? Y Refer report G-1.2 Hoists, Cranes and Operating Mechanisms 1.2.1 Are the hoists working satisfactorily? Y 1.2.2 Any problems inspecting hoist/crane/operating mechanism? N Is sufficient stock of spares which need frequent replacement 1.2.3 N No spares are seen maintained maintained at the site? Is the full length of the chains or wire rope of the hoist in sound 1.2.4 Y condition and free from broken strands? 1.2.5 Is the electrical wiring in sound condition? Y 1.2.6 Is the alternative power system for gate operation working properly? Y New DG set installed as part of DRIP-I Fair 1.2.7 Is the alternate hand operation system of hoist working properly? Y Any deterioration of equipment (connecting bolts, welds, surface, 1.2.8 N paint work?) 1.2.9 Any wear or damage to wire cables and other moving parts? N 1.2.10 Any obstructions preventing or impairing smooth operation? N Any health and safety concerns (e.g. lack of "danger" sign during 1.2.11 N maintenance)? 1.2.12 Any other issues? Y 223 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Spillway Bridge, Hoist Bridge, Trunnion Level Bridge G 1.3. Catwalks Are the decking, girders and structural supports of spillway bridge, 1.3.1 Y hoist bridge, trunnion level bridge and catwalks structurally sound? 1.3.2 Is the chequered platform of the bridge structurally sound and safe? Y Is there satisfactory arrangement to prevent unauthorized entry into 1.3.3 Y the control structures and bridges? Are the structural members and joints sound and free from 1.3.4 Y corrosion? Fair 1.3.5 When were the steel components painted last? Y 04/2018 (Partial) 1.3.6 Is the surface of steel work and paints satisfactory? N 1.3.7 Is the parapet or railing over the bridges sound, safe and painted? Y 1.3.8 Is the walkway properly anchored to the piers? Y 1.3.9 Are the track rails for gantry cranes structurally sound and intact? NA G-1.4 Valves 1.4.1 Any problems inspecting valve? NA 1.4.2 Any obstructions preventing or impairing smooth operation? NA 1.4.3 Any deterioration of valve and associated equipment? NA 1.4.4 Any other issues? NA Walls: Guide walls/Divide walls/Junction walls/Return G-1.5 walls/Spray walls etc. 224 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Are all the locations of such wall accessible for inspection, 1.5.1 Y maintenance and repairs? Is the drainage of back sides of the walls (wherever applicable) from 1.5.2 Y the weep holes satisfactory? If not, indicate the nature of deficiencies. 1.5.3 Is there any tendency for the water to undercut the ends of the walls? N Is there any foundation erosion or scour noticed in the vicinity of 1.5.4 such walls? If so, give the details of nature and extent of such N Satisfactory damage. Is there any surface erosion/damage caused, to face or body of such 1.5.5 N walls? Do any of the walls show symptoms of unusual settlement, 1.5.6 developments of cracks and tilting? If so, give details of the defects N noticed. 1.5.7 Is there any damage to guide bunds? If so, give details of the damage. NA G-1.6 End Weir No end weir 1.6.1 Is it accessible? NA Is there any erosion, pitting or spalling of the concrete or 1.6.2 NA masonry surface? If so, give details Is there any scour noticed on the immediate downstream of such 1.6.3 NA weir? If so, give details of location and extent of such damage. G-1.7 Hydraulic Performance of Energy Dissipation Arrangements Do the flow conditions in the stilling basin (or bucket) have a tendency to draw material into the bucket and cause its churning and abrasion damage to the surface of buckets baffle blocks, apron and end sill? Is the hydraulic performance in agreement with the results of Tail water rating curves to be prepared for 1.7.1 N model studies? (wherever applicable) Ascertain the performance from checking the energy dissipation efficiency observed tail water rating curves and deficient observation, if any, such as sweep outs and excessive erosion under plunge pools and locations of secondary rollers and retrogression. 225 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory G-1.8 Trash Racks Fixed (one at penstock opening, other at 1.8.1 Is the trash rack fixed or movable? NA sluice opening) 1.8.2 What is the mode of cleaning? Is it manual or by TRCM? Manual 1.8.3 Is the welding work on Trash Rack in sound health? N Cannot inspect as the water level is above Trash 1.8.4 Any problems inspecting trash rack? N Fair rack 1.8.5 Problems of excessive debris and/or inadequate cleaning? Y 1.8.6 Any deterioration of trash rack (rust, corrosion, and damaged blades)? Can't inspect the water level above Trash rack 1.8.7 Any other issues? G-1.9 Trash Rack Cleaning Machines 1.9.1 Any problems inspecting trash rack cleaning machine? NA Trash Rack cleaning Machines not available Missing or inadequate spare parts (particularly requiring regular 1.9.2 NA replacement)? Any deterioration of equipment (wheel trolleys, gantry structures, 1.9.3 NA operating mechanism, connecting bolts, welds, surface, paint work?) 1.9.4 Any wear or damage to wire cables and other moving parts? NA 1.9.5 Any obstructions preventing or impairing smooth operation? NA 1.9.6 Missing or inadequate provision of back-up/standby power supply? NA Any health and safety concerns (e.g. lack of "danger" sign during 1.9.7 NA maintenance)? 226 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory 1.9.8 Any other issues? NA G-1.10 Pumps 1.10.1 Any problems inspecting pump? N 1.10.2 Any obstructions preventing or impairing smooth operation? N Satisfactory 1.10.3 Any deterioration of pump and associated equipment? N 1.10.4 Any other issues? N G-1.11 Approach bridge, operation platform and cabin (for outlets): Are the decking, girders and structural supports of approach bridge 1.11.1 structurally sound? 1.11.2 Is the floor of the operating platform structurally sound and safe? Y Is there satisfactory arrangement to prevent unauthorized entry into 1.11.3 N the control structures of the outlet? Fair Are the structural members and joints sound and free from 1.11.4 Y corrosion? 1.11.5 When were the steel components painted last? Y In 04/2018 1.11.6 Is the surface of steel work and paint satisfactory? Y Is the parapet or railing over the control tower, operating 1.11.7 Y platform and approach bridge sound and safe? G-1.12 Outlet No outlet 1.12.1 Is the air vent periodically cleaned? NA 1.12.2 Are there any structural damages to the intake well? NA Is there any leakage observed through the well proper and the 1.12.3 conduit concrete or masonry? If so, give details of its location and NA extent. Is there any damage noticed to the conduit concrete, breast wall and 1.12.4 NA gate slots? Is the bye-pass valve/filling-in-valve (wherever provided) 1.12.5 NA operating satisfactory? 227 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Take operation trials of the following as provided and record the observations and defects noticed, if any. (1) Service gate(s). Sluice valve operating properly (2) Emergency gate(s). (3) Stop-log gate(s). NA (4) Sluice valves. NA Fair Note- (i) The operating trial for the emergency gate shall be taken with service gate in partially open position to test the capability of emergency gate for self-closing under these conditions. The trial for the operation of the emergency gate under balanced condition of water pressure also needs to be taken (ii) To guard against the possibility of outlet gate hoist being operated forcibly after closed position of gate a “Distinctive Mark” should be insisted or check the functioning of the limit switches. Are there vibrations and noise noticed in operation of out- let gates at 1.12.6 any time? If so, please indicate if periodical observations have been N taken to ascertain their severity. Is the energy dissipation arrangement working satisfactorily for all the 1.12.7 discharges?Is there any structural damage to the energy dissipation NA Dewatering is to be done to identify the problems structure? If so, give details of nature and extent of damage. Is the conduit structurally sound and reasonably leak proof? If not, 1.12.8 NA give details of nature and extent of the defects. -do- Is there any seepage noticed around the conduit as ascertained from 1.12.9 the observations of the downstream conditions? If so, please indicate NA if it is likely to cause erosion and piping (In case of earth dams). -do- G-1.13 Outlet Gates Work tendered, water level has to be lowered 1.13.1 Is the surface of gates and the paint deteriorated? Y below sill level for executing the work 228 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Are the connecting bolts of rubber seals properly tightened or 1.13.2 Y damaged? Do the rubber seals show signs of weathering and damage and need 1.13.3 Y Same as G 1.13.1 replacements? Are the rubber seals of sides and bottom touching the bearing surface 1.13.4 Y uniformly? 1.13.5 Do all the rollers touch the track plates? NA No rollers attached 1.13.6 Are the rollers well lubricated? NA No rollers attached 1.13.7 Are the stem rods for lifting the gates perfectly straight? Y Is the operation of outlet gates smooth?Are the actual operations of 1.13.8 lifting and lowering of the gates and hoist mechanisms adequate and Y smooth? Fair 1.13.9 Are all the gears and hoist mechanisms well lubricated? Y Is the storing arrangement for emergency gate leaves and the stop 1.13.10 NA logs in satisfactory condition? 1.13.11 Are the seal plates/seats in sound condition? Y Is the full length of wire rope (wherever applicable) of the hoist in 1.13.12 NA No wire ropes system attached serviceable condition and free from any broken strands? 1.13.13 Are all the nuts of connecting bolt and anchors properly tightened? Y Are all the lifting beams in proper working order and in levelled condition? If not, ascertain the nature and extent of problems. Do 1.13.14 NA any of the mechanical or structural parts of the gate, fasteners of hoist show signs of excessive wear? If so, please give details. Is there any tendency for recurring damage to any particular 1.13.15 N component or components? If so, please give details. Is sufficient stock of spares, which need frequent replacement, Recommended strictly essential spares and tools at 1.13.16 N maintained at the site? site G-1.14 River Outlet/River Sluice 229 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Is the overall condition of river outlet works/river sluices 1.14.1 NA satisfactory? Is the operation of the gate (Service/Emergency/Stop-log) 1.14.2 satisfactory as ascertained by taking operating trial? If not, indicate the NA defects noticed. Are the trash racks (wherever provided) cleaned before 1.14.3 NA monsoon? Cannot inspect as the water level is 39.90m against 1.14.4 Is there excessive silting on the upstream of the sluice? NA FRL 42m 1.14.5 When were the gates last opened for desilting, etc.? NA Not opened for desilting Fair Please indicate the approximate quantity of the leakage through the 1.14.6 NA Not ascertained gates, if any. 1.14.7 Is there any seepage or leakage through the conduit surface? NA Is there any damage to the upstream and downstream Cannot inspect as the water level is 39.90m against 1.14.8 NA convergence of the conduit? FRL 42m Is the condition of energy dissipation arrangement satisfactory? If 1.14.9 NA Dewatering required for inspection not, indicate nature and extent of damage. Is there any retrogression noticed in the downstream channel? If so, 1.14.10 NA give details of nature and extent of damage. H-1 Access Road H-1.1 General Condition Any problems ensuring security of dam site (including gates and 1.1.1 N fencing)? Is there a properly constructed and well maintained all weather access 1.1.2 Y road to the dam site? What is the type of the pavement of the access road and its Bituminous and concrete roads and are in good 1.1.3 condition? condition 230 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Are there properly constructed and well maintained access road arrangements to the following components for inspection, maintenance and repairs? Top of Dam Spillway Gates and hoisting 1.1.4 arrangement Drainage gallery, adits and exits Bridge structure Y Downstream stilling basin Junction and abutments Outet control tower Outlet gates Toe of earth dam, downstream drainage arrangements and berms. All saddle dams. Fair Are all the masonry structures on various access roads in good 1.1.5 Good condition condition? Are all the structures on the access roads adequately safe for allowing 1.1.6 Y passage of plant machinery for emergent repairs? Any obstructions along or at entrance to access road (temporary or 1.1.7 N long-term)? 1.1.8 Any slope stability issues (road embankment or adjacent slopes)? N 1.1.9 Profuse growth of weeds/grass on or in vicinity of access road? N 1.1.10 Any drainage problems (standing water on or adjacent to road)? N Any other degradation to road surface (ruts, potholes, cavities, 1.1.11 N cracking)? 1.1.12 Any other issues? N I-1 Instrumentation I-1.1 General Condition Are all the instruments installed accessible? (Attach separate list).Are 1.1.1 all the locations properly lighted, ventilated and adequately protected NA No instrumentation provided from possibilities of damage? 1.1.2 Any problems inspecting instrument (obstructed/unsafe access)? NA Is the instrument vulnerable to damage or theft (inadequate 1.1.3 NA protection)? Any problems ensuring correct functioning of instrument (lighting, 1.1.4 NA ventilation)? Any evidence of degradation to condition of instrument (rusting, 1.1.5 NA vandalism)? Are all the instruments in working order? Ascertain the cases of Poor 1.1.6 NA instruments going out of order and indicate. Are all the registers of observations posted up-to-date? Please take 1.1.7 NA test observations and initial the register. 231 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Are all the plotting of the instrumentation data completed up-to-date? 1.1.8 Are sufficient stocks of spares, gauges, master gauges, stationary NA items etc., maintained at the site for uninterrupted data collection? 1.1.9 Operator or public safety issues? NA 1.1.10 Any other issues? NA I-1.2 Communication Facilities Are following facilities available at dam site? (1) 1.2.1 Y Mobile and Internet only Wireless Telephone / mobile/Fax/Internet Fair 1.2.2 Any other issue (please indicate part, location, etc., as necessary) NA K-1 Emergency Preparedness K-1.1. Emergency Action Plan Is the Emergency Action Plan (EAP) prepared for the dam as per the 1.1.1 national guidelines? If not, the expected date of preparation of Y guidelines 1.1.2 When EAP was last updated? EAP was prepared and finalized in July 2019 If not, are any dam staff unaware or insufficiently conversant with the 1.1.3 NA EAP? Any concerned authorities unaware or insufficiently conversant with 1.1.4 N the EAP? Are communication directories/contact details and other dynamic 1.1.5 YNA information are being updated annually? Any problems accessing or operating the communication/ warning 1.1.6 Y Siren needs to be provided to alert the people system? 1.1.7 Are inundation maps updated and available to concerned authorities? Y As mentioned in EAP Fair Are the concerned authorities informed about the system of 1.1.8 Y -do- emergency reporting procedures and warning? Are available safety spots on the downstream of the dam identified 1.1.9 and made known to the concerned authorities? Are adequate warning Y devices and facilities provided at the dam? Are proper arrangements made for security of the dam and 1.1.10 preventing cases of unauthorized trespass, vandalism and sabotage to Y the dam works? 232 Response Condition ( Observations and Recommendations, if any, Unsatisfactory/P Sl No Inspection Item of the authorized inspecting officer oor/Fair/Satisfa YNNA ctory Date of last annual stakeholder consultation meeting along with mock 1.1.11 NA yet to be conducted drill exercise conducted 1.1.12 Has the EAP been disseminated to all the concerned stakeholders? Y 1.1.13 Any other issues? K-1.2 Inspection of Records Have the following Dam Safety Documents been prepared and 1.2.1 approved by the competent authority? I. As Built Drawings N II. EAP Y Fair III. Completion Report N IV. Data Book Y V. O and M manual N Under preparation 1.2.2 Are the relevant documents reviewed and updated from time to time? Y Are all the members of the maintenance staff adequately trained 1.2.3 and fully conversant with their responsibilities concerning. (a) Designer’s Operation Criteria. (b) Standing Operating Procedures. Training required for (c) Maintenance and Vigilance Procedures of the dam. all the operation staff Poor (d) Maintenance and operation of all control equipments. (e) Reservoir Operation Schedules, Gate Operation Schedule N (f) Maintenance and Operation of all instruments. (g) Identification of signs of deficient behavior. (h) Reporting Procedures of emergency situations. (i) Emergency repairs L-1.1 Inspection Photographs Appended 1.1.1 Information to be furnished as per Annexure - II 233 234 ANNEXURE II CHECKLIST OF VARIOUS INSTRUMENTS INSTALLED ON LARGE DAMS Name of Dam: MUVATTUPUZHA VALLEY IRRIGATION PROJECT – MALANKARA DAM Location: IDDUKKI Date last Agency Analysis Since calibratio Data sent Whether responsibl of data when n Observation to DSO Sl. in working e for data done at Name of Instruments Nos. Location installed Date for s maintained regularly Remarks No. condition collection field (Month/ next (Yes/No) (Yes/No) and level ? Year) calibratio (Yes/No) processing (Yes/No) n (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) HYDRO‐METEOROLOGICAL INSTRUMENTS 1. Raingauge on Dam Raingauge in the 2. Catchment 3. Pan Evaporimeter To be fixed Wind Velocity 4. Recorder Wind Direction 5. Recorder 6. Wave Height Recorder Wet and dry bulb 7. Thermometer 8. Barometer 9. Thermometers for air 235 Date last Agency Analysis Whether calibratio Data sent Since when Observation responsibl of data in n to DSO Sl. installed s e for data done at Name of Instruments Nos. Location working Date for regularly Remarks No. (Month/ maintained collection field condition next ? Year) (Yes/No) and level (Yes/No) calibratio (Yes/No) processing (Yes/No) n (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) Temp. 10. Thermometers for reservoir water temp. 11. Automatic weather station 12. Reservoir level gate (i) Staff gate (ii) Automatic GEO-TECHNICAL INSTRUMENTS 1. Piezometers (i) Stand pipe (ii) Casagrande (iii) Twin tube 236 Date last Agency Analysis Since calibratio Data sent Whether responsibl of data when n Observation to DSO Sl. in working e for data done at Name of Instruments Nos. Location installed Date for s maintained regularly Remarks No. condition collection field (Month/ next (Yes/No) (Yes/No) and level ? Year) calibratio (Yes/No) processing (Yes/No) n (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (iv) Vibrating wire Uplift pressure cell (i) For permeable 2. foundation (ii) For Rock foundation Strain Gauge (i) Mechanical Strain 3. Gauge (ii) Electrical Strain Gauge Strain Meter 4. (i) Vibrating wire Thermometers 5. (i) Resistance (ii) Vibrating Wire Stress Meter 6. (i) Mechanical (ii) Electrical 7. Seepage Measurement 237 Date last Agency Analysis Since calibratio Data sent Whether responsibl of data when n Observation to DSO Sl. in working e for data done at Name of Instruments Nos. Location installed Date for s maintained regularly Remarks No. condition collection field (Month/ next (Yes/No) (Yes/No) and level ? Year) calibratio (Yes/No) processing (Yes/No) n (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (i) V‐Notch (ii) Other devices Automation (i) Data logger 8. (ii) Data Acquisition system (iii) Computers (i) Plumb Bob – Direct (ii) Plumb Bob – Inverted (iii) Detachable Gauges for Surface Displacement 9. (iv) Joint meter for internal joint movement (v) Tilt Meter (vi) Foundation Settlement Deformation Meter (vii) Inclinometer 238 Date last Agency Analysis Since calibratio Data sent Whether responsibl of data when n Observation to DSO Sl. in working e for data done at Name of Instruments Nos. Location installed Date for s maintained regularly Remarks No. condition collection field (Month/ next (Yes/No) (Yes/No) and level ? Year) calibratio (Yes/No) processing (Yes/No) n (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) Other Geotechnical Instruments, if any 10. (i) (ii) (iii) GEODETIC INSTRUMENTS 1. Total Station NA 2. Survey Markers NA 3. Settlement Plates NA SEISMIC INSTRUMENTS 1. Seismograph NA 2. Accelerograph NA 239 O&M Manual of Malankara Dam August 2020 Annexure- F Pre Monsoon Inspection Report PRE MONSOON INSPECTION REPORT Dam Name MALANKARA Project ID Code(PIC) KL 07 MH 0049 Dam Type Earth cum Masonry dam Dam purpose IRRIGATION Dam Owner Water Resource Department, Kerala Hazard classification II Significant Dam Operator Kerala Irrigation Department Type of inspection PRE MONSOON INSPECTION Executive Engineer, MVIP Division No III Commissioning Date 1994 Inspection By Muvattupuzha City/Date/PIN Thodupuzha/Kerala/685587 Date of Inspection 04.05.2020 Reservoir water level in District IDUKKI meter on the date of 41.42M inspection Lattitude between Latitude 9° 37’& 10 0 4 north Storage Capacity 34.92Mm3 33-32 Longitude Between Longitude 76° 26’& 76 0 49’ east Weather condition humidity 68% wind speed 25km /hr a)MWL +43.00m b)FRL +42.00m Important Controlling Level c)Spillway Crest +36.90m d)MDDL +28.00m e)Deepest foundation level +22.00m 240 O&M Manual of Malankara Dam August 2020 Embankment/Masonry Dam Checklist Condition ( Observations and Response Unsatisfacto Recommendations, if Sno Inspection Item ry/Poor/Fai any, of the authorized r/Satisfactor Y N NA inspecting officer y A-Reservoir A-1.1 General Condition Is the reservoir water level 1.1.1 N unusually high or low? Are there signs of decline 1.1.2 N in water quality? Are there signs of recent 1.1.3 N sediment deposition? Upstream face of 1.1.4 Is floating debris present? Y penstock Any indications of major active or inactive landslide 1.1.5 area in the reservoir rim? N If so, indicate their locations and extent. Eviction of encroachments near the dam body & reservoir boundary are in progress Are there people or based on GO(MS) 1.1.6 livestock in and around Y No.29/2018/wrd dtd reservoir? 29/06/2018. Fencing and compond wall are constructed around the dam premises in drip work. 1.1.7 Any other issues? N B-Dam and Dam Reach (Embankment) B-1.1 General Condition Any major alterations or 1.1.1 changes to the dam since N the last inspection? Rivertraining wall Is there any new nearby constructed at left side 1.1.2 development in the N downstream of downstream floodplain? dam(DRIP) Any misalignment of 1.1.3 poles, fencing or walls due N to dam movement? 241 O&M Manual of Malankara Dam August 2020 B-1.2 Upstream Slope Any signs of bulging or concavity (depressions)? If so, indicate their locations 1.2.1 and extent. (Check up the N cross-sections with tape and level at random locations, at least two) Does the section of the dam and upstream slope 1.2.2 Y appear structurally sound and stable? Presence of longitudinal or 1.2.3 N transverse cracks? Any signs of distress to stability of slopes noticed at any time in any part of the dam? If so, give brief details of the incidents and 1.2.4 N location, the method of treatment adopted and its effectiveness. Indicate the general condition of upstream pitching. Any degradation to slope 1.2.5 N protection (rip-rap)? Is there any profuse growth of bushes or weeds 1.2.6 over any portion of the N dam? If so, indicate the locations. Does the upstream slope shows existence of crab holes or holes made by 1.2.7 N rodents or burrowing animals or ant hills? If so, indicate the locations. 1.2.8 Any other issues? N B-1.3 Crest of Dam Is the crest profile at proper elevation? (To be 1.3.1 Y test checked at random locations by taking level) 242 O&M Manual of Malankara Dam August 2020 Does it show any signs of excessive and/or uneven settlement? If so, indicate such locations and extent 1.3.2 N of settlement. (Surface settlement points must be installed for observing this aspect) Is the surface of the crest free from undulations and 1.3.3 N local depressions or heaving? Does it provide an all- 1.3.4 Y weather road surface? Any degradation to access 1.3.5 N road (sealed/unsealed)? Does it develop any visible cracks in transverse or longitudinal directions? If so, attach a map showing 1.3.6 their locations and extent. N Depth of cracks must be ascertained by taking open trenches extending below the bottom of cracks. Have the edges of the crest gotten eroded and 1.3.7 N cut up resulting in reduced effective width? Is the crest free from local 1.3.8 slips throughout its length Y on either sides? Do the headers, guard stones and parapet wall 1.3.9 provided at the edges of Y the crest appear in proper profile and plumb? Any degradation to 1.3.10 upstream parapet or N downstream curb wall? Evidence of livestock on 1.3.11 N dam crest? Trees or profuse growth of 1.3.12 weeds/bushes at any N location? Proper lighting 1.3.13 Y arrangement at dam top? Done in Drip work. 243 O&M Manual of Malankara Dam August 2020 1.3.14 Any other issues? N B-1.4 Downstream Slope Any signs of bulging or 1.4.1 N concavity (depressions)? Are there any wet or lekage seen in down slushy patches or any stream of earthern dam concentrated leaks, springs portion. or trickles observed on the downstream slopes or the toe? If so, indicate their 1.4.2 Y locations and extent. Please look out for patches of extensive vegetation growth and examine them carefully and record the findings. Presence of longitudinal or 1.4.3 N transverse cracks? Any signs of distress to the 1.4.4 N stability of slopes? Are rain cuts/erosion 1.4.5 channels present at any N location? Are all the rain cuts and erosion channels properly 1.4.6 treated and made good? NA Please indicate location of recurring damages, if any. Is there any profuse growth of bushes or weeds 1.4.7 over any portion of the N dam? If so, indicate the locations. Does the downstream slope show existence of crab holes or holes made 1.4.8 N by rodents or burrowing animals or ant hills? If so, indicate the locations. Any other degradation to slope protection (turfing)? Indicate the general 1.4.9 N condition of downstream pitching/ turfing and rock toe. Is the downstream area 1.4.10 Y clear of debris and freely 244 O&M Manual of Malankara Dam August 2020 draining? 1.4.11 Any other issues? N B-1.5 Downstream Drainage Are there any signs of water logging, slushy conditions or growth of 1.5.1 aquatic weeds on the N downstream of the dam? To be checked upto 300 m downstream of toe Are there any standing pools of water in the downstream of dam? If so, 1.5.2 give their locations and N extent. To be checked upto 300 m downstream of toe Are there any boils observed in the vicinity of 1.5.3 N the downstream toe of the dam? If so, give locations. Is the downstream area 1.5.4 sufficiently clear and freely Y draining? What is the depth of a)Max.GWL- 30.85m ground water table on the b) length is-75m from toe downstream as evident drain. 1.5.5 from the existing wells in C) Location-D/s of dam. the vicinity of the dam? To d) Date-04.05.2020 be checked upto 300 m e)Corresponding downstream of toe. Reservoir level-41.42m Does the water table show any marked variation in 1.5.6 accordance with the Y variations in reservoir water level? Are all the exposed drains 1.5.7 Y working satisfactorily? Toe drains and cross 1.5.8 drains: i. Are the portions of longitudinal toe drain and exposed cross drains Y beyond the downstream toe of the dam in regular section and freely 245 O&M Manual of Malankara Dam August 2020 draining? ii. Is the pitching Y to these drains intact? iii. Is there any weed growth in these N drains? iv. Any other defects N noticed in the drains?. 1.5.9 Outfall Drain: (a) Is the outfall drain in 1.5.12 proper shape and grade Y and freely draining? (b) Is the outfall drain 1.5.13 properly cleaned and Y maintained? Does the outfall drain 1.5.14 show any stagnant pools N of water or weed growth? B-1.6 Surface Drainage of Downstream Slope Is the condition of the downstream slope 1.6.1 Y drainage arrangements, if provided, satisfactory? Is the paving to these 1.6.2 Y drains intact? Are all the drains properly maintained and 1.6.3 Y free of vegetation growth and debris? Does the slope have a 1.6.4 tendency to develop severe N rain cuts at any location? Any other defects noticed 1.6.5 in the surface drainage of N downstream slope? B-1.7 Seepage Measurement Is the quantity of seepage being daily or periodically 1.7.1 measured and recorded? Y Please check the registers and record observations. Does it show any abnormal rise or fall? If so, 1.7.2 N explain if it has any relation to a certain 246 O&M Manual of Malankara Dam August 2020 reservoir level elevation. Does the seepage show a turbid colour at any stage? Indicate if such a 1.7.3 N phenomenon has been observed at any stage, at any location in the past. What is the measured rate 1.7.4 of seepage flow with date and reservoir level: a)Date-04.05.2020 b)Rate of seepage i. On the day of flow(lpm)-39.0364lit/m present inspection c) Reservoir level(m)- 41.42m a)Date-08-01-2020 b)Rate of seepage ii. Maximum flow(lpm)- 51.005 lit/m since last June c) Reservoir level(m)- 41.20m a)Date-07-09-2019 b)Rate of seepage iii. Minimum flow(lpm)-26.096 lit/m since last June- c) Reservoir level(m)- 36.90m Is the portion upstream and downstream of measuring points of 1.7.5 seepage easily accessible with proper steps and paths and free of vegetation growth? Y Are the measuring points properly located, constructed and maintained so as to give 1.7.6 accurate and reliable measurements of seepage in accordance with the relevant IS Codes? Y Is the method of taking 1.7.7 seepage measurements satisfactory? Y B-1.8 Breaching Section (if provided) Is the breaching section 1.8.1 easily accessible? NA 247 O&M Manual of Malankara Dam August 2020 Is the condition of the 1.8.2 breaching section satisfactory? NA Is the note of instructions as to when and how to 1.8.3 operate the breaching section available on record? NA For reconstruction after the breach, are the 1.8.4 following items decided in advance? NA a) Quarry for embankment material NA b) Suitable routes of access NA Is the maintenance staff fully aware of the instructions related to 1.8.5 operation of the beaching section and for reconstruction after the breach ? NA Ascertain and indicate the latest event of operation of 1.8.6 breaching section and its performance. NA Evidence of recent 1.8.7 degradation? NA 1.8.8 Any other issues? NA B-1.9 Junction of Earth work with Masonry/Concrete dam sections and outlets Is there any existence of leaks, springs or wet spots in the earth work in the vicinity of the junctions between earth work and Main seepage water came masonry works? If so, to inspection gallery from 1.9.1 please indicate the Y junction of earthern and approximate rate and masonry portion. colour of the leakage and if it turns turbid at any time. Please ascertain from enquiries and record the findings. 248 O&M Manual of Malankara Dam August 2020 Is there any tendency for separations, cracking, settlement or upheaval of the earth work in the 1.9.2 vicinity of masonry or concrete? If so, indicate the locations and the exact nature of deficiency. N Is there any tendency for 1.9.3 surface erosion or slope instability at the junction? N If the outlet conduit is located in the earth dam section, is the entire length of the conduit in perfect order and profile and free from offsets, open joints, 1.9.4 cracks and leakage? Examine the conduit carefully from the downstream or from inside, if possible, and indicate the deficiencies observed, if any. NA 1.9.5 Any other issues? N B-1.10 Relief Wells Are the relief wells in 1.10.1 good working condition and functioning well? NA Are the relief wells 1.10.2 properly surged and cleaned periodically? NA Please indicate the dates of 1.10.3 last surging and cleaning and the next surging due. NA Are the necessary plant and equipment for 1.10.4 cleaning the relief wells, available with the office? NA Is the record of periodical measurements of discharge from each relief well maintained? If so, indicate 1.10.5 total discharge and maximum discharge observed from a single well on the date of inspection. NA 249 O&M Manual of Malankara Dam August 2020 B-1.11 Abutment Contacts Any presence of leaks, 1.11.1 springs or wet spots near the abutment? N Any presence of cracking, 1.11.2 settlement or upheaval of earthwork? N Any evidence of erosion or 1.11.3 slope instability? N Trees or profuse growth of 1.11.4 weeds/bushes? N Any degradation to up/downstream slope 1.11.5 protection (rip-rap, turfing)? N 1.11.6 Any other issues? N D Gallery/Shaft and Drainage D-1.1 General Condition Slushy condition or water 1.1.1 logging immediately downstream of dam? N Any evidence of boiling in 1.1.2 vicinity of dam toe? N D-1.2 Gallery/Shaft Condition Any problems accessing or 1.2.1 inspecting gallery/shaft (obstruction)? N Handrails are to be urgently provided on D/S Any safety issues of river training wall. 1.2.2 (inadequate handrails, Y Included in DRIPsavings lighting or ventilation)? amount work and work started Problems of inadequate drainage (slippery stairs, 1.2.3 water logging of gallery, clogged porous or foundation drains)? N Evidence of differential settlement 1.2.4 (displaced/offset/open joints)? N Excessive seepage/sweating at any 1.2.5 location along gallery/shaft? N 250 O&M Manual of Malankara Dam August 2020 Significant or excessive leakage at any location 1.2.6 along gallery/shaft / porous drain? If yes, provide location(s). N Are proper arrangements Seepage measured only 1.2.7 made for the measurement from foundation drains. of seepage into the gallery? Y Is the seepage measured Separate arrangement separately from Porous are to be provided for 1.2.8 pipes, Foundation drains porous pipes and and Monolith Joints? N monolith joints. More arrangements to be Are the above 1.2.9. required as above arrangements satisfactory? N required Has there been substantial progressive reduction in the seepage through the foundations? Indicate if it 1.2.10. NA is due to choking of the drain holes and if so, indicate the number of choked holes. Are all the foundation and Cleaning of foundation porous holes periodically and porous holes done in cleaned with reaming tool January 2016 and now and air water jetting? the work tendered Indicate the last date of 1.2.11. such cleaning and extent of variation observed in the seepage discharge before and after the cleaning. Y Is the seepage water and Seepage water tested on the deposit, if any, from 04.07.2019 the seepage being regularly examined for chemical 1.2.12 composition? If so, indicate the result and the probable source of dissolved salts, if any. Y 251 O&M Manual of Malankara Dam August 2020 Are any seepage water springs observed in the downstream area any where? If so, indicate the locations and state the physical nature of this 1.2.13. seepage. Look out for such seepage spots particularly near the dykes, fault zone etc. Ascertain if chemical testings are made of water samples from such springs for dissolved salts. N Is there any leachate 1.2.14 deposition? If yes provide location N 1.2.15 Any other issues? N D-1.3 Drain Condition Is the flow in the drain 1.3.1 unusually high or low? N Presence of calcium or 1.3.2 other deposits in drain? Y Is the dewatering pumping 1.3.3 station fully operational? Y Any problem inspecting 1.3.4 the pump? N Any obstruction 1.3.5 preventing or impairing smooth operation? N Any deterioration of pump 1.3.6 and associated equipment? N Is the sump well clean and 1.3.7 maintained? Y Is the V-notch before 1.3.8 sump well cleaned and maintained? Y Any other evidence of the drain being 1.3.9 blocked/having reduced section? N Is the flow in the drain 1.3.10 noticeably sporadic/irregular? N Does the drainage water 1.3.11 have unusual color (leachate)? N 1.3.12 Any other issues? N 252 O&M Manual of Malankara Dam August 2020 D-1.4 Body Wall (Masonry/Concrete) of ‘NOF’ Dam What is the total seepage into gallery from the porous pipes in the dam at lake full condition? 1.4.1 Compare it with the seepage when the reservoir was first filled. (For the corresponding water level) Y Has there been substantial reduction in this seepage? 1.4.2 Ascertain and indicate the probable reasons therefore. N Has there been a tendency for gradual reduction of drainage through pipes and 1.4.3 progressive appearance of sweating on the downstream face of the dam? N Has there been considerable leaching from 1.4.4 the seepage water and deposition of lime near the seepage exit spots? N Are the samples of the seepage water and 1.4.5 reservoir water being regularly tested for reactive and corrosive properties? Y Is there excessive seepage, sweating at any locations on the downstream face of the dam? ( Examine 1.4.6 the monolith or construction joints for such seepage and leaching and indicate the findings) N Is there any swelling or cracking observed on the downstream face especially near the points of concentration of stresses 1.4.7 like the toe or locations of abrupt change in geometry of the face of the opening? If so, indicate the details of observations. N 253 O&M Manual of Malankara Dam August 2020 Is the pointing on upstream face of the dam 1.4.8 in good condition? If not, indicate the nature and extent of deficiency. Y Are the registers and graphs showing the periodical measurements of seepage discharge from 1.4.9 the porous drains in the gallery and from the downstream face at various lake levels maintained at site? N E Spillway and Energy Dissipation Structure E 1.1 Spillway Any problems inspecting 1.1.1 spillway (obstructed access, damaged catwalk)? N Any obstructions in or 1.1.2 immediately downstream of the spillway? N Evidence of abrasion, cavitation or scour on 1.1.3 glacis (e.g. exposed reinforcement)? N Presence of displaced, 1.1.4 offset or open joints? N Presence of cracking 1.1.5 (structural, thermal, along joints)? N Evidence of surface 1.1.6 defects (honeycombing, staining, stratification)? N Concrete/masonry 1.1.7 deterioration (spalling, leaching, disintegration)? N Presence of vegetation 1.1.8 (growth in joints between blocks)? N Evidence of any other 1.1.9 damage to joints and/or waterstops? N Excessive 1.1.10 seepage/sweating at any location on spillway glacis? N Significant leakage at any 1.1.11 location on spillway glacis? N 254 O&M Manual of Malankara Dam August 2020 1.1.12 Any other issues? N E 1.2 Waste Weir Bar and Tail Channel Is the Concrete/masonry spillway bar in good condition? Indicate if there is any leakage through the masonry or from the foundation. If so, what remedial measures are 1.2.1 Y proposed/taken for minimizing the leakage? Is the record of leakage measurement maintained? What is the quantity of Seepage/Leakage on the date of inspection? Is the coping over the 1.2.2 spillway bar in good condition? Y Does the upstream and 1.2.3 downstream face of waste weir bar need pointing? N Is there any scouring on downstream side of the 1.2.4 bar and/or EDA? If so what remedial measures are proposed/taken? N Are there any damages or undermining to guide walls, divide wall and other 1.2.5 appurtenants? If so, indicate what remedial measures are proposed/taken. N E 1.3 Structural performance of the ‘NOF’ and ‘OF’ Portions of Dam Foundations Are there any signs of structural distress noticed 1.3.1 in the dam spillway and foundations in the form of- i. Excessive deflection with respect to permissible deflection at the time of design N ii. Tendency of gradual sliding N 255 O&M Manual of Malankara Dam August 2020 iii. Cracking and upheaval or settlement in any part of the body wall or foundations, N iv. Excessive uplift, N v. Excessive seepage and leaching through the body of the dam and the foundation. N Conspicuous weathering of materials or 1.3.2 components in any portion of the body wall or the foundations. N E-1.4 Energy Dissipation Structure Any problems inspecting 1.4.1 energy dissipation structure? N Any obstructions in or 1.4.2 immediately downstream of dissipation structure? N Evidence of abrasion, 1.4.3 cavitation or scour on Not visible due to the dissipation structure? presence of water Presence of displaced, 1.4.4 Not visible due to the offset or open joints? presence of water Presence of cracking 1.4.5 (structural, thermal, along Not visible due to the joints)? presence of water Evidence of surface 1.4.6 defects (honeycombing, Not visible due to the staining, stratification)? presence of water Concrete/masonry 1.4.7 deterioration (spalling, Not visible due to the leaching, disintegration)? presence of water Presence of vegetation 1.4.8 (growth in joints between blocks)? N Evidence of any other 1.4.9 damage to joints? N Any problems with under- 1.4.10 drainage (blockage of open drain holes)? N Can the tail pond be drained easily for 1.4.11 inspection of the stilling basin or bucket? If not, Only pumping is required indicate the alternatives N for dewatering 256 O&M Manual of Malankara Dam August 2020 available for dewatering. Please ascertain and indicate the last event of inspection of stilling basin (or bucket). From the examination of the levels and contour plans and reference marks in tail channel; is there progressive erosion and retrogression in the tail 1.4.12 channel? If so, indicate the extent and location of such erosion with reference to the various components of dam, spillway, outlet, Not examined due to the power house etc. presence of water Is the concrete surface of the stilling basin and apron 1.4.13 (or bucket) in good Not fully visible due to condition? the presence of water Are there any indications of pitting, cracking, spalling or wearing of the 1.4.14 surface of bedding concrete? If so, please give details of the nature and Not fully visible due to extent of the damage. the presence of water Is there any indication of abrasion and cavitation damage (pitting of concrete) especially at friction blocks , chute 1.4.15 blocks and slotted roller teeth, the surface near the lower tangent point and the end sill? If so, please give the details of nature Not examined due to and extent of damage. presence water Is the under drainage of the stilling basin (or 1.4.16 bucket) satisfactory? Are all the open drain holes Not examined due to clear and functioning well? presence water 1.4.17 Any other issues? N G-1.5 Walls: Guide walls/Divide walls/Junction walls/Return walls/Spray walls etc. 257 O&M Manual of Malankara Dam August 2020 Are all the locations of such wall accessible for 1.5.1 inspection, maintenance and repairs? NA Is the drainage of back sides of the walls (wherever applicable) from 1.5.2 the weep holes satisfactory? If not, indicate the nature of deficiencies. NA Is there any tendency for 1.5.3 the water to undercut the ends of the walls? NA Is there any foundation erosion or scour noticed in the vicinity of such walls? 1.5.4 If so, give the details of nature and extent of such damage. NA Is there any surface 1.5.5 erosion/damage caused, to face or body of such walls? NA Do any of the walls show symptoms of unusual settlement, developments 1.5.6 of cracks and tilting? If so, give details of the defects noticed. NA Is there any damage to 1.5.7 guide bunds? If so, give details of the damage. NA G-1.6 End Weir 1.6.1 Is it accessible? N Is there any erosion, pitting or spalling of the 1.6.2 concrete or masonry surface? If so, give details N Is there any scour noticed on the immediate downstream of such weir? 1.6.3 If so, give details of location and extent of such damage. N G-1.7 Hydraulic Performance of Energy Dissipation Arrangements 258 O&M Manual of Malankara Dam August 2020 Do the flow conditions in the stilling basin (or bucket) have a tendency to draw material into the 1.7.1 bucket and cause its churning and abrasion damage to the surface of buckets baffle blocks, Unable to examine due to apron and end sill? water Is the hydraulic performance in agreement 1.7.2 with the results of model studies? (wherever applicable) N Ascertain the performance from observed tail water rating curves and deficient observation, if any, such as 1.7.3 sweep outs and excessive Not examined erosion under plunge pools and locations of secondary rollers and retrogression. F Intake/Outlet and Water Conveyance Structure F-1.1 Intake/Outlet Structure Any problems inspecting intake/outlet structure 1.1.1 (obstructed/unsafe access)? N Any obstructions in, 1.1.2 upstream or downstream of intake/outlet structure? N Evidence of abrasion, 1.1.3 cavitation or scour on intake/outlet structure? N Any evidence of structural distress 1.1.4 (displaced/offset/open joints, cracking)? N Any evidence of surface defects and/or 1.1.5 concrete/masonry deterioration? N 1.1.6 Any other issues? F-1.2 Water Conveyance Structure Any problems inspecting 1.2.1 intake/outlet structure N 259 O&M Manual of Malankara Dam August 2020 (obstructed/unsafe access)? Any obstructions in, upstream or downstream 1.2.2 of water conveyance structure? N Evidence of abrasion, 1.2.3 cavitation or scour on structure? N Any evidence of structural distress 1.2.4 (displaced/offset/open joints, cracking)? N Any evidence of surface 1.2.5 defects and/or material deterioration? N Any evidence of seepage 1.2.6 or leakage from water conveyance structure? N 1.2.7 Any other issues? G-1 Hydro-Mechanical Component and Pump G-1.1 Spillway Gates (Radial gates, Vertical lift gates, Automatic gates) Any problems inspecting gate/Stop-logs 1.1.1 (obstructed/unsafe access)? N Is the condition of the 1.1.2 steel surface and the surface paint deteriorated? N Are any connection bolts of rubber seals loosened or 1.1.3 damaged? If so, indicate the details of defects. N Do any of the rubber seals show signs of 1.1.4 weathering, hardening, cracking or tearing and damage? N Are the rubber seals of side and bottom touching 1.1.5 uniformly all along the sealing surface? N Do the rollers (wherever applicable) touch the track 1.1.6 plates uniformly? Are the rollers well lubricated? Y 260 O&M Manual of Malankara Dam August 2020 Are the embeded parts of spillway gates, emergency gates and stop-logs in sound condition and free from corrosion, uneven 1.1.7 wear, cracking, chipping and dents? If not, state the nature of defects or deficiencies and observation, if any, regarding such defects. N Are the following members and welded, bolted and riveted connections structually 1.1.8 sound? If not, please give details of any uneven wear, uneven bearing, cracking, chipping and dents and indicate the findings: (1) Gate leaf and stiffeners Y (2) End arms Y (3) Trunnion girders / Yoke girder Y (4) Stop logs (5) Lifting beams (6) Gantry cranes (7) Tracks Y (8) Trunnion bracket Y (9) Chains/ wire ropes Y (10) Bridge structure Y Are the trunnion bearings 1.1.9 of radial gates properly lubricated? Y Is there any damage or wear caused to the seal 1.1.10 plates? If so, indicate the nature of damage noticed. N Are any of the mechanical or structural components 1.1.11 and fastners or seals subjected to excessive wear? If so, please give N 261 O&M Manual of Malankara Dam August 2020 details. Is there any tendency for recurring damage to any 1.1.12 particular component? If so, please give details. N Is sufficient stock of spares which need 1.1.13 frequent replacement maintained at the site? NA Any issues with storage of equipment (emergency 1.1.14 stop logs, lifting beam and gate leaves)? N Any deterioration, corrosion? scaling? pitting? 1.1.15 or cracking? of equipment (connecting bolts, welds?) N Any obstructions 1.1.16 preventing or impairing smooth operation? N Any problems with the rollers (not touching 1.1.17 tracks, inadequate lubrification)? N Any debris, etc., in the gate 1.1.18 grooves? N Any damages to Radial 1.1.19 Gate trunion pins? gate arms? lubrication? etc.? N Any damage to embedded 1.1.20 parts above waterline? access structure? N Any damage to concrete 1.1.21 grooves? Y Is the staff posted at the site for maintenance and operation of gates, hoists, equipments and electrical 1.1.22 installations, well experienced, fully trained and conversant with the job requirements and responsibilities? Y Are the following 1.1.23 documents maintained at the respective location of 262 O&M Manual of Malankara Dam August 2020 all the units? (1) Maintenance schedules specifying each operation, its frequency and ‘due’ and’ done’ dates. N (2) Operating instructions with ‘dos’ and ‘don’t’ for all operational units. N Are the trunnion hub and 1.1.24 the brackets well maintained? Y Are the trunnions likely to get submerged during actual working of the spillway? if so, ascertain 1.1.25 the causes for the same and specify. Please enquire for occurrence of such events, if any. N Are all the nuts of connecting bolts and 1.1.26 anchorages properly tightened? Y 1.1.27 Any other issues? N G-1.2 Hoists, Cranes and Operating Mechanisms Are the hoists working 1.2.1 satisfactorily? Y Any problems inspecting 1.2.2 hoist/crane/operating mechanism? Y Is sufficient stock of spares which need 1.2.3 frequent replacement maintained at the site? N Is the full length of the chains or wire rope of the 1.2.4 hoist in sound condition and free from broken strands? Y Is the electrical wiring in 1.2.5 sound condition? NA Is the alternative power 1.2.6 system for gate operation working properly? Y 263 O&M Manual of Malankara Dam August 2020 Is the alternate hand 1.2.7 operation system of hoist working properly? Y Any deterioration of equipment (connecting 1.2.8 bolts, welds, surface, paint work?) N Any wear or damage to 1.2.9 wire cables and other moving parts? NA Any obstructions 1.2.10 preventing or impairing smooth operation? N Any health and safety concerns (e.g. lack of 1.2.11 "danger" sign during maintenance)? Y 1.2.12 Any other issues? N G 1.3. Spillway Bridge, Hoist Bridge, Trunnion Level Bridge Catwalks Are the decking, girders and structural supports of spillway bridge, hoist 1.3.1 bridge, trunnion level bridge and catwalks structurally sound? Y Is the chequered platform 1.3.2 of the bridge structurally sound and safe? Y Is there satisfactory arrangement to prevent 1.3.3 unauthorized entry into the control structures and bridges? Y Are the structural members and joints 1.3.4 sound and free from corrosion? Y When were the steel 1.3.5 Painting work done components painted last? during 4/2018 Is the surface of steel work 1.3.6 and paints satisfactory? Y Is the parapet or railing 1.3.7 over the bridges sound, safe and painted? Y Is the walkway properly 1.3.8 anchored to the piers? Y 264 O&M Manual of Malankara Dam August 2020 Are the track rails for 1.3.9 gantry cranes structurally sound and intact? NA G-1.4 Valves Any problems inspecting 1.4.1 valve? NA Any obstructions 1.4.2 preventing or impairing smooth operation? NA Any deterioration of valve 1.4.3 and associated equipment? NA 1.4.4 Any other issues? NA G-1.8 Trash Racks Is the trash rack fixed or 1.5.1 movable? NA What is the mode of 1.5.2 cleaning? Is it manual or by TRCM? Is the welding work on 1.5.3 Trash Rack in sound health? Any problems inspecting 1.5.4 trash rack? N Problems of excessive 1.5.5 debris and/or inadequate cleaning? Any deterioration of trash 1.5.6 rack (rust, corrosion, and damaged blades)? 1.5.7 Any other issues? G-1.9 Trash Rack Cleaning Machines Any problems inspecting 1.6.1 trash rack cleaning machine? NA Missing or inadequate spare parts (particularly 1.6.2 requiring regular replacement)? NA Any deterioration of equipment (wheel trolleys, gantry structures, 1.6.3 operating mechanism, connecting bolts, welds, surface, paint work?) NA Any wear or damage to 1.6.4 wire cables and other NA 265 O&M Manual of Malankara Dam August 2020 moving parts? Any obstructions 1.6.5 preventing or impairing smooth operation? NA Missing or inadequate 1.6.6 provision of back- up/standby power supply? NA Any health and safety concerns (e.g. lack of 1.6.7 "danger" sign during maintenance)? NA 1.6.8 Any other issues? NA G-1.10 Pumps Any problems inspecting 1.7.1 pump? N Any obstructions 1.7.2 preventing or impairing smooth operation? N Any deterioration of pump 1.7.3 and associated equipment? N 1.7.4 Any other issues? N G-1.11 Approach bridge, operation platform and cabin (for outlets): Are the decking, girders and structural supports of 1.8.1 approach bridge structurally sound? Y Is the floor of the operating platform 1.8.2 structurally sound and safe? Y Is there satisfactory arrangement to prevent 1.8.3 unauthorized entry into the control structures of the outlet? Y Are the structural members and joints 1.8.4 sound and free from corrosion? Y When were the steel Painting work done 1.8.5 components painted last? during 4/2018 Is the surface of steel work 1.8.6 and paint satisfactory? Y 266 O&M Manual of Malankara Dam August 2020 Is the parapet or railing over the control tower, 1.8.7 operating platform and approach bridge sound and safe? Y G-1.12 Outlet Is the air vent periodically 1.9.1 cleaned? Y Are there any structural 1.9.2 damages to the intake well? Y Is there any leakage observed through the well proper and the conduit 1.9.3 concrete or masonry? If so, give details of its location and extent. Y Is there any damage noticed to the conduit 1.9.4 concrete, breast wall and gate slots? Y Is the bye-pass valve/filling-in-valve 1.9.5 (wherever provided) operating satisfactory? Take operation trials of the following as provided and record the observations and defects noticed, if any. N (1) Service gate(s). (2) Emergency gate(s). (3) Stop-log gate(s). (4) Sluice valves. Note- (i) The operating trial for the emergency gate shall be taken with service gate in partially open position to test the capability of emergency gate for self- closing under these conditions. The trial for the operation of the emergency gate under balanced condition of water pressure also needs to be taken Y 267 O&M Manual of Malankara Dam August 2020 (ii) To guard against the possibility of outlet gate hoist being operated forcibly after closed position of gate a “Distinctive Mark” should be insisted or check the functioning of the limit switches. Are there vibrations and noise noticed in operation of out- let gates at any 1.9.6 time? If so, please indicate if periodical observations have been taken to ascertain their severity. N Is the energy dissipation arrangement working 1.9.7 satisfactorily for all the discharges? NA Is there any structural damage to the energy 1.9.8 dissipation structure? If so, give details of nature and extent of damage. N Is the conduit structurally sound and reasonably leak 1.9.9 proof? If not, give details of nature and extent of the defects. Is there any seepage noticed around the conduit as ascertained from the observations of the 1.9.10 downstream conditions? If so, please indicate if it is likely to cause erosion and piping (In case of earth dams). G-1.13 Outlet Gates Is the surface of gates and 1.10.1 the paint deteriorated? N Are the connecting bolts 1.10.2 of rubber seals properly tightened or damaged? Y Good condition Do the rubber seals show 1.10.3 signs of weathering and damage and need Y Good condition 268 O&M Manual of Malankara Dam August 2020 replacements? Are the rubber seals of sides and bottom touching 1.10.4 the bearing surface uniformly? Y Do all the rollers touch the 1.10.5 track plates? NA Are the rollers well 1.10.6 lubricated? NA Are the stem rods for 1.10.7 lifting the gates perfectly straight? Y Is the operation of outlet 1.10.8 gates smooth? Y Are the actual operations of lifting and lowering of 1.10.9 the gates and hoist mechanisms adequate and smooth? Y Are all the gears and hoist 1.10.10 mechanisms well lubricated? Y Is the storing arrangement for emergency gate leaves 1.10.11 and the stop logs in satisfactory condition? NA Are the seal plates/seats in 1.10.12 sound condition? Y Is the full length of wire rope (wherever applicable) 1.10.13 of the hoist in serviceable condition and free from any broken strands? NA Are all the nuts of connecting bolt and 1.10.14 anchors properly tightened? Are all the lifting beams in proper working order and 1.10.15 in levelled condition? If not, ascertain the nature and extent of problems. NA Do any of the mechanical or structural parts of the 1.10.16 gate, fasteners of hoist show signs of excessive NA 269 O&M Manual of Malankara Dam August 2020 wear? If so, please give details. Is there any tendency for recurring damage to any 1.10.17 particular component or components? If so, please give details. N Is sufficient stock of spares, which need 1.10.18 frequent replacement, maintained at the site? N G-1.14 River Outlet/River Sluice Is the overall condition of 1.11.1 river outlet works/river sluices satisfactory? Y Is the operation of the gate (Service/Emergency/Stop- log) satisfactory as 1.11.2 ascertained by taking operating trial? If not, indicate the defects noticed. N Are the trash racks 1.11.3 (wherever provided) cleaned before monsoon? NA Is there excessive silting 1.11.4 on the upstream of the sluice? NA When were the gates last 1.11.5 opened for desilting, etc.? NA Please indicate the Having small leakages approximate quantity of through the sluice 1.11.6 the leakage through the chamber gates, if any. Is there any seepage or 1.11.7 leakage through the conduit surface? NA Is there any damage to the upstream and 1.11.8 downstream convergence of the conduit? NA Is the condition of energy dissipation arrangement 1.11.9 satisfactory? If not, indicate nature and extent of damage. NA 270 O&M Manual of Malankara Dam August 2020 Is there any retrogression noticed in the downstream 1.11.10 channel? If so, give details of nature and extent of damage. NA H-1 Access Road H-1.1 General Condition Any problems ensuring security of dam site 1.1.1 (including gates and fencing)? N Is there a properly constructed and well 1.1.2 maintained all weather access road to the dam site? Y What is the type of the Bitumineous & concreate 1.1.3 pavement of the access roads are in good road and its condition? Y condition. Are there properly constructed and well maintained access road arrangements to the following components for inspection, maintenance and repairs? Top of Dam Spillway Gates and hoisting 1.1.4 arrangement Drainage gallery, adits and exits Bridge structure Downstream stilling basin Junction and abutments Outet control tower Outlet gates Toe of earth dam, downstream drainage arrangements and berms. All saddle dams. Y Are all the masonry structures on various 1.1.5 access roads in good condition? Y Are all the structures on the access roads adequately 1.1.6 safe for allowing passage of plant machinery for emergent repairs? Y 271 O&M Manual of Malankara Dam August 2020 Any obstructions along or 1.1.7 at entrance to access road (temporary or long-term)? N Any slope stability issues 1.1.8 (road embankment or adjacent slopes)? N Profuse growth of 1.1.9 weeds/grass on or in vicinity of access road? N Any drainage problems 1.1.10 (standing water on or adjacent to road)? N Any other degradation to road surface (ruts, 1.1.11 potholes, cavities, cracking)? 1.1.12 Any other issues? N I-1 Instrumentation I-1.1 General Condition Are all the instruments 1.1.1 installed accessible? (Attach separate list). NA Are all the locations properly lighted, ventilated 1.1.2 and adequately protected from possibilities of damage? NA Any problems inspecting instrument 1.1.3 (obstructed/unsafe access)? NA Is the instrument vulnerable to damage or 1.1.4 theft (inadequate protection)? NA Any problems ensuring correct functioning of 1.1.5 instrument (lighting, ventilation)? NA Any evidence of degradation to condition 1.1.6 of instrument (rusting, vandalism)? NA Are all the instruments in working order? Ascertain 1.1.7 the cases of instruments going out of order and NA 272 O&M Manual of Malankara Dam August 2020 indicate. Are all the registers of observations posted up-to- 1.1.8 date? Please take test observations and initial the register. NA Are all the plotting of the 1.1.9 instrumentation data completed up-to-date? NA Are sufficient stocks of spares, gauges, master gauges, stationary items 1.1.10 etc., maintained at the site for uninterrupted data collection? NA Operator or public safety 1.1.11 issues? NA 1.1.12 Any other issues? NA I-1.2 Communication Facilities Are following facilities available at dam site? 1.2.1 (1) Wireless Telephone / Mobile phone, Satellite mobile/Fax/Internet Phone and internet Any other issue (please 1.2.2 indicate part, location, etc., as necessary) K-1 Emergency Preparedness K-1.1. Emergency Action Plan Is the Emergency Action Plan (EAP) prepared for the dam as per the national 1.1.1 guidelines? If not, the expected date of preparation of guidelines Y When EAP was last 1.1.2 updated? Nov-18 If not, are any dam staff 1.1.3 unaware or insufficiently conversant with the EAP? NA Any concerned authorities 1.1.4 unaware or insufficiently conversant with the EAP? NA Are communication 1.1.5 directories/contact details and other dynamic Y 273 O&M Manual of Malankara Dam August 2020 information are being updated annually? Any problems accessing or operating the 1.1.6 communication/ warning system? N Are inundation maps 1.1.7 updated and available to concerned authorities? Y Are the concerned authorities informed about 1.1.8 the system of emergency reporting procedures and warning? Y Are available safety spots on the downstream of the 1.1.9 dam identified and made known to the concerned authorities? Y Are adequate warning 1.1.10 devices and facilities Mobile phone, Satellite provided at the dam? N Phone and internet Are proper arrangements made for security of the dam and preventing cases 1.1.11 of unauthorized trespass, vandalism and sabotage to the dam works? Y Date of last annual stakeholder consultation 1.1.12 meeting along with mock drill exercise conducted not conducted Has the EAP been to District Disaster 1.1.13 disseminated to all the Management Authority, concerned stakeholders? Idukki and Ernakulam 1.1.14 Any other issues? K-1.2 Inspection of Records Have the following Dam Safety Documents been 1.2.1 prepared and approved by the competent authority? I. As Built Drawings Y II. EAP Y III. Completion Report Y IV. Data Book Y V. O and M manual N submitted 274 O&M Manual of Malankara Dam August 2020 Are the relevant documents reviewed and 1.2.2 updated from time to time? Y Are all the members of the maintenance staff 1.2.3 adequately trained and fully conversant with their responsibilities concerning. (a) Designer’s Operation Criteria. (b) Standing Operating Procedures. (c) Maintenance and Vigilance Procedures of the dam. Y (d) Maintenance and operation of all control equipments. Y (e) Reservoir Operation Schedules, Gate Operation Schedule Y (f) Maintenance and Operation of all instruments. Y (g) Identification of signs of deficient behavior. Y (h) Reporting Procedures of emergency situations. Y (i) Emergency repairs Y L-1.1 Inspection Photographs Information to be 1.1.1 furnished as per Annexure - II 275 O&M Manual of Malankara Dam August 2020 Annexure-G NOTIFICATION FOR STRENGTHENING OF ALARM AND WARNINGSYSTEM FOR SAFETY OF PEOPLE FROM SUDDEN RELEASE OF WATERFROM DAMS ISSUED BY NATIONAL DISASTER MANAGEMENT AUTHORITY(OCTOBER 2015) Introduction Dams are delivering enormous benefits to the nation through flood risk mitigation, navigation, irrigation, hydropower, water supply, fisheries, wildlife conservation and recreation. Dams storelarge amount of water; and an uncontrolled or excessive outflow of water from dam reservoirmay pose unacceptable risks to the lives and property of people downstream of dam. Sometimes,unexpected release of even small quantum of water during day to day operation of dam reservoirscould also catch people unaware, and cause loss of lives - recent Larji dam incident (June, 2014) is the tragic example which resulted in drowning of 25 students in the river Beas inHimachal Pradesh. Strengthening of alarm and warning system linked with dam operations cango a long way in ensuring safety of people from sudden release of water through dam spillways. Scope This notification is intended to strengthen the alarm and warning system on India's dams forsafety of people from sudden release of water through dam spillways/river sluices. It is also expectedthat the notification will sensitize and guide the dam operating staff in identifying, monitoring,and responding to emergency situation that may arise at any downstream stretch of theriver due to sudden release of water from dam. Applicability This notification is applicable for enforcement by all dam authorities in charge of operation ofthe dams. This is particularly applicable to barrages and independent outlet works which are directlydischarging into the river. Measures for Strengthening of Alarm and Warning System 1. Reservoir Operation Manual, prescribing standard operating procedures for the day to day as well as emergency operations of dam, shall be prepared by the concerned project authorities/dam owners (State Governments, Public Sector Undertakings, other government or privateagencies). The Operation Manual shall spell out all possible scenarios of operation of spillwaygates and other outlet gates keeping in perspective the elevation-storage curve of thereservoir; the annual inflow pattern of the reservoir; the annual water demand pattern of theproject; and in case of hydropower projects, the power demand and impact of load rejectionon generating units. 276 O&M Manual of Malankara Dam August 2020 2. The concerned project authorities shall carry out hydraulic routing studies for the downstreamriver reaches for different dam-outflow conditions in order to identify vulnerable areasin terms of depth/level and velocity of flows. In such vulnerable areas, project authoritiesshall mark danger levels at appropriate places and set up permanent warning posts (in English,Hindi and the local language) visible with naked eyes from reasonable distances. Movablebarriers may be installed to prevent the entry of people and vehicles during passage offlood. 3. The purpose of a flood warning service is to detect and forecast threatening flood events sothat the public can be alerted in advance and undertake appropriate responses to minimizethe impact of flood. The components of a flood warning system can be aptly illustrated infigure below. 4. The vulnerable areas that pose very highrisk levels (e.g. river reaches very c se to dam locations)shall be fenced to bar free access of people. Development of river front from thepoint-of- viewof tourism shall be allowed only at safe places; and in all such places amplecare shall be taken to prominently notify risks associated with sudden release of wafer fromdam. 5. The concerned project authorities shall establish a Control Room to keep watch on probablewater inflows so as to have advance information and sufficient lead time for protectivemeasures. A proper coordinate ion regarding releases of water during both normal andemergent conditions shall be ensured with the immediate upstream and other cascading projects. The work of Control Room shall be entrusted to duly qualified persons. 6. A foolproof warning system to alert downstream habitants before release of water shall beput in place. The warning for release of water shall be given through Speakers, Sirens orHooters adequately in advance of dam releases (minimum 15 minutes); and all such instrumentsshall be directly connected to the Control Room eliminating dependence on watchstaffstationed at vulnerable areas. The warning system shall be backed up by alternate powersources in Control Room as well as vulnerable locations so as to avoid malfunctioning ofsystem in case of power failures. The Sirens/ Hooters shall be distinguishable from othercommon sounds like VIP vehicles, fire brigades, ambulance etc. Regular Inspection shall becarried out to ensure all time functioning of sirens, and periodical mock drills shall also beplanned for ensuring efficacy of the warning system. 7. Tourists entering the vulnerable zones shall be forewarned of dangers of sudden dam releases.A suitable mechanism shall be developed in consultation with pertinent telecom serviceproviders to send SMSs to such tourists whenever they enter vulnerable zones. Attemptsshall also be made to send SMSs related to extreme releases of water to all mobile phonesoperating in the downstream vicinity of the dam project. 277 O&M Manual of Malankara Dam August 2020 8. For dealing with extreme weather and flood conditions, accurate and reliable hydro meteorologicalnetwork, inflow forecasting and communication mechanism shall be established bythe State Governments. Releases from the storage dams associated with irrigation and floodmoderation shall be planned in advance with the help of telemetry data available on real timebasis, and advance warnings shall be issued to the people. Such information related to floodestimates and planned releases from dams shall be made available on Project website andthrough other means of public dissemination. 9. The concerned project authorities shall develop appropriate mechanism to keep local administrationinformed about the extreme inflows, sudden release of water and any other exigencyconditions. Directory of contact numbers of key persons of civil administration, police, ambulance,fire station etc. shall be available with the officials responsible for such communications,and a copy shall also be available in the Control Room. Regular revision/updating ofthe Directory shall be carried out for its meaningful intent. 10. Preparation of Emergency Action Plan (EAP) for each dam is crucial for minimizing the lossof life and property in the event of occurrence of any emergency situation. A typical EAPcontains procedures and information to assist the dam owner in taking necessary actions intime to moderate or alleviate the problems, in addition to issuing early warning and notificationmessages to responsible authorities, viz., District Magistrate/Collector, Armed forces,Paramilitary forces, Project Authorities and other Central/State Agencies. It also contains inundationmaps to identify critical areas for prioritization of relief and rescue actions in caseof an emergency. Project Authorities shall ensure preparation and up-dation of the EAPs oftheir dams as per Central Water Commission's guidelines available on CWC website athttp://www.cwc.gov.in/main/downloads/EAP chapter.pdf. 278 O&M Manual of Malankara Dam August 2020 279 O&M Manual of Malankara Dam August 2020 Annexure- H-- GLOSSARY Abutment ― that part of a valley side against which a dam is constructed. Right and left abutments are those on respective sides of an observer looking downstream. Air-Vent Pipe ― a pipe designed to provide air to the outlet conduit to reduce turbulence during release of water and safeguard against damages due to cavitation. Appurtenant Structures ― ancillary features of a dam, such as the outlet, spillway, energy dissipation arrangement powerhouse, tunnels, etc. Arch Dam ― a concrete or masonry dam that is curved to transmit the major part of the water pressure to the abutments. Auxiliary Spillway (Emergency Spillway)― a secondary spillway designed to operate only during exceptionally large floods. Backwater Curve ― the longitudinal profileof the water surface in an open channel where the depth of flow has been increased by an obstruction, an increase in channel roughness, a decrease in channel width, or a flattening of the bed slope. Base Width (Base Thickness) ― the maximum width or thickness of a dam measured horizontally between upstream and downstream faces and normal (perpendicular) to the axis of the dam but excluding projections for outlets, etc. Berm ― a horizontal step or bench in the sloping profile of an embankment dam. Bulkhead gate ― a gate used either for temporary closure of a channel or conduit to empty it for inspection or maintenance or for closure against flowing water when the head difference is small, e.g., for diversion tunnel closure. Although a bulkhead gate is usually opened and closed under nearly balanced pressures, it nevertheless may be capable of withstanding a high pressure differential when in the closed position. Buttress dam ― a dam consis ng of a water tight upstream face supported at intervals on the downstream side by a series of buttresses. Cofferdam ― a temporary structure enclosing all or part of a construction area so that construction can proceed in a dry area. Concrete Lift ― in concrete works the ver cal distance between successive horizontal construction joints. Conduit Outlet Works ― a closed conduit for conveying discharge through or under a dam for different project purposes. 280 O&M Manual of Malankara Dam August 2020 Consolida on Grou ng (Blanket Grou ng)― the injection of grout to consolidate a layer of the foundation, resulting in greater impermeability, strength, or both. Construction Joint ― the interface between two successive placings or pours of concrete where a bond, not permanent separation, is intended. Core Wall ― a wall built of impervious material, usually concrete or asphaltic concrete, in the body of an embankment dam to prevent leakage. Crest gate (spillway gate) ― a gate on the crest of a spillway to control overflow or reservoir water level. Crest Length ― the length of the dam at its crest (dam top) top of a dam, including the length of the spillway, powerhouse, navigation lock, fish pass, etc., where these structures form part of the length of a dam. If detached from a dam, these structures should not be included. Crest of dam ― Used to indicate the ―top of dam‖. To avoid confusion to indicate the crest of spillway and top of dam may be used. Culvert ― a drain or waterway built under a road, railway, or embankment, usually consisting of a pipe or covered conduits Cutoff― an impervious construc on or material which reduces seepage through the foundation material. Cutoff trench ― an excava on later to be filled with impervious material to form a cut off. Cutoff wall ― a wall of impervious material (e.g., concrete, asphal c concrete, steel-sheet piling) built into the foundation to reduce seepage under the dam. Dam – any artificial barrier including appurtenant works constructed across rivers or tributaries thereof with a view to impound or divert water; includes barrage, weir and similar water impounding structures but does not include water conveyance structures such as canal, aqueduct and navigation channel and flow regulation structures such as flood embankments, dikes, and guide bunds. Dam failure – failures in the structures or operation of a dam which may lead to the uncontrolled release of impounded water resulting in downstream flooding affecting the life and property of the people. Dam incident – all problems occurring to a dam that has not degraded into ‗dam failure‘ and including the following: a) Structural damage to the dam and appurtenant works; b) Unusual readings of instruments in the dam; c) Unusual seepage or leakage through the dam body; 281 O&M Manual of Malankara Dam August 2020 d) Change in the seepage or leakage regime; e) Boiling or artesian conditions noticed below an earth dam; f) Stoppage or reduction in seepage or leakage from the foundation or bodyof the dam into any of the galleries, for dams with such galleries; g) Malfunctioning or inappropriate operation of gates; h) Occurrence of any flood, the peak of which exceeds the available flood discharge capacity or 70% of the approved design flood; i) Occurrence of a flood, which resulted in encroachment on the available freeboard, or the adopted design freeboard; j) Erosion in the near vicinity, up to five hundred meters, downstream of the spillway, waste weir, etc.; and k) Any other event that prudence suggests would have a significant unfavorable impact on dam safety. Dam inspection – on-site visual examination of all components of dam and its appurtenances by one or more persons trained in this respect and includes investigation of the non-overflow portion, spillways, abutments, stilling basin, piers, bridge, downstream toe, drainage galleries, operation of mechanical systems (including gates and its components, drive units, cranes), interior of outlet conduits, instrumentation records, and record-keeping arrangements. Dam owner – the Central Government or a State Government or public sector undertaking or local authority or company and any or all of such persons or organizations, who own, control, operate or maintain a specified dam. Dam safety – the practice of ensuring the integrity and viability of dams such that they do not present unacceptable risks to the public, property, and the environment. It requires the collective application of engineering principles and experience, and a philosophy of risk management that recognizes that a dam is a structure whose safe function is not explicitly determined by its original design and construction. It also includes all actions taken to identify or predict deficiencies and consequences related to failure, and to document, publicize, and reduce, eliminate, or remediate to the extent reasonably possible, any unacceptable risks. Dead storage ― the storage that lies below the invert of the lowest outlet and that, therefore, cannot be withdrawn from the reservoir. Decommission ― Taking a dam out of service in an environmentally sound and safe manner, or converting it to another purpose. Design flood ― see spillway design flood. 282 O&M Manual of Malankara Dam August 2020 Design life ― the intended period that the dam will function successfully with onlyroutine maintenance; determined during design phase. Diaphragm ― see membrane. Dike (Levee) ― a long low embankment whose height is usually less than 5 m and whose length is more than 10 times the maximum height. Usually applied to embankments or structures built to protect land from flooding. If built of concrete or masonry, the structure is usually referred to as a flood wall. Also, used to describe embankments at block areas on a reservoir rim that are lower than the top of the main dam and that are quite long. In the Mississippi River basin, where the old French word levee has survived, the term now applies to flood-protecting embankments whose height can average up to 15 m. Distress condition – the occurrence or potential development of such conditions in the dam or appurtenance or its reservoir or reservoir rim, which if left unattended to, may impede the safe operation of dam for its intended benefits or may pose unacceptable risks to the life and property of people downstream. Diversion channel, canal, or tunnel ― a waterway used to divert water from its natural course. These terms are generally applied to temporary structures such as those designed to bypass water around a dam site during construc on. ―Channel‘ is normally used instead of ―canal‖ when the waterway is short. Occasionally these terms are applied to permanent structures. Documentation – all permanent records concerning investigation, design, construction, operation, performance, maintenance and safety of dams and includes design memorandum, construction drawings, geological reports, reports of specialized studies simulating structural and hydraulic response of the dam, changes made in design and drawings, quality control records, emergency action plan, operation and maintenance manual, instrumentation readings, inspection and testing reports, operational reports, and dam safety review reports; Drainage area ― an area that drains naturally to a point on a river. Drainage layer or blanket ― a layer of permeable material in a dam to relieve porepressure or to facilitate drainage of fill. Drawdown ― the lowering of water surface level due to release of water from a reservoir. Earth dam (Earth fill dam) ― An embankment dam in which more than 50 percent of the total volume is formed of compacted fine-grained material obtained from a borrow area. Earthen dam or earth fill dam ― see embankment dam. Embankment dam (Fill dam) ― any dam constructed of excavated natural materials. 283 O&M Manual of Malankara Dam August 2020 Emergency Action Plan (EAP) ― a plan of action to be taken to reduce the potential for damage to property and loss of life in the area affected by failure of a dam or other potentially hazardous practice. Emergency gate ― a standby or reserve gate which is lowers only for repairing/ servicing of the service gate. Emergency spillway ― see spillway. Face ― the external surface of a structure, e.g., the surface of a wall of a dam. Failure ― the uncontrolled release of water from a dam. Filter (filter zone) ― A band or zone of granular material that is incorporated into adam and is graded (either naturally or by selection) to allow seepage to flow across or down the filter without causing the migration of material from zones adjacent to it. Fixed wheel gate (fixed-roller gate fixed-axle gate) ― a gate having wheels or rollers mounted on the end posts of the gate. The wheels move against rails fixed inside grooves or gate guides. Flap gate ― a gate hinged along one edge, usually either the top or bottom edge. Examples of bottom-hinged flap gates are tilting gates and belly gates, so called due to their shape in cross- section. Flashboards ― a length of mber, concrete, or steel placed on the crest of a spillway to raise the retention water level but that may be quickly removed in the event of a flood, either by a tripping device or by deliberately designed failure of the flashboard or its supports. Flood gate ― a gate to control flood release from a reservoir. Flood routing ― the determination of the attenuating effect of storage on a flood passing through a valley, channel, or reservoir. Flood surcharge ― the volume or space in a reservoir between the controlled retention water level (Full Reservoir Level) and the maximum water level. Flood surcharge cannot retained in the reservoir but will flow over the spillway until the controlled retention water level is reached. Flood wall ― a concrete wall constructed adjacent to a stream to prevent flooding of property on the landward side of the wall, normally constructed in lieu of or to supplement a levee where the land required for levee construction is expensive or not available. Floodplain ― an area adjoining a body of water or natural stream that has been, or may be, covered by flood water. Floodplain management ― a management program to reduce the consequences of flooding, either by natural runoff or by dam failure, to existing and future properties in a floodplain. Foundation of dam ― the natural material on which the dam structure is placed. 284 O&M Manual of Malankara Dam August 2020 Freeboard ― the ver cal distance between a stated reservoir level and the top of a dam. Normal freeboard is the vertical distance between Full Reservoir Level (FRL) and the top of the dam. Minimum freeboard is the vertical distance between the Maximum Water Level (MWL) and the top of the dam. Full Reservoir Level (FRL)/Normal water level ― for a reservoir with un-gated spillway it is the spillway crest level. For a reservoir, whose outflow is controlled wholly or partly by movable gates, siphons or other means, it is the maximum level to which water can be stored under normal operating conditions, exclusive of any provision for flood surcharge. Fuse-Plug Spillway ― an auxiliary or emergency spillway comprising a low embankment or a natural saddle designed to be overtopped and eroded away during a rare and exceptionally large flood. Gallery ― (a) a passageway within the body of a dam or abutment, hence the terms grouting gallery, inspection gallery and drainage gallery (b) a long and rather narrow hall, hence the following terms for a power plant viz. valve gallery, transformer gallery and bus bar gallery. Gate ― a device in which a leaf or member is moved across the waterway from an external position to control or stop the flow. Gravity dam ― a dam constructed of concrete, masonry, or both that relies on its weight for stability. Grout cap ― a pad or wall constructed to facilitate pressure grou ng of the grout curtain beneath it. Grout curtain (grout cutoff) ― a barrier produced by injec ng grout into a ver cal zone, usually narrow horizontally, in the foundation to reduce seepage under a dam. Guard gate (guard valve) ― a gate or valve that operates fully open or closed. It may func on as a secondary device for shutting off the flow of water in case the primary closure device becomes inoperable, but is usually operated under conditions of balanced pressure and no flow. Hazard Classification ― a system that categorizes dams according to the degree of adverse incremental consequences of a failure or improper operation of the dam. CWC classifies dam hazards as low, significant, or high. Height above lowest foundation ― the maximum height from the lowest point of the general foundation to the top of the dam. Homogeneous earth fill dam ― an embankment dam constructed of similar earth material throughout, except internal drains or drainage blankets; distinguished from a zoned earth fill dam. Hydraulic fill dam ― an embankment dam constructed of materials, often dredged, thatare conveyed and placed by suspension in flowing water. 285 O&M Manual of Malankara Dam August 2020 Hydraulic height ― the height to which water rises behind a dam and the difference between the lowest point in the original streambed at the axis of the dam and the maximum controllable water surface. Hydrograph ― a graphic representa on of discharge, stage, or other hydraulic property with respect to time for a point on a stream.(At times the term is applied to the phenomenon the graphic representation describes; hence a flood hydrograph is the passage of a flood discharge past the observation point.) Inclinometer ― an instrument, usually consis ng of a metal or plas c tube inserted in a drill hole and a sensitized monitor either lowered into the tube or fixed within it. The monitor measures at different points the tube‘s inclination to the vertical. By integration, the lateral position at various levels of the tube may be found relative to a point, usually the top or bottom of the tube, assumed to be fixed. The system may be used to measure settlement. Intake ― any structure in a reservoir, dam, or river through which water can be drawn into an aqueduct. Internal Erosion ― see piping. Inundation map ― a map delinea ng the area that would be inundated in case of a failure. Leakage ― Uncontrolled loss of water by flow through a hole or crack. Lining ― a coa ng of asphal c concrete, reinforced or unreinforced concrete, shotcrete, rubber or plastic on a canal, tunnel etc. to provide water tightness, prevent erosion, reduce friction, or support the periphery of structure. May also refer to lining, such as steel or concrete, of outlet pipe or conduit. Low-level outlet (bottom outlet) ― an opening at a low level from a reservoir generally used for emptying or for scouring sediment and sometimes for irrigation releases. Maintenance ― the recurring ac vi es necessary to retain or restore a dam in a safe and functioning condition, including the management of vegetation, the repair or replacement of failed components, the prevention or treatment of deterioration, and the repair of damages caused by flooding or vandalism. Masonry dam ― a dam constructed mainly of stone, brick, or concrete blocks that may or may not be joined with mortar. A dam having only a masonry facing should not be referred to as a masonry dam. Maximum cross-section of dam ― across-section of a dam at the point of itsmaximum height. Maximum water level ― the maximum water level, including flood surcharge, the dam is designed to withstand. 286 O&M Manual of Malankara Dam August 2020 Membrane (Diaphragm) ― a sheet or thin zone or facing made of a flexible material, sometimes referred to as a diaphragm wall or diaphragm. Minimum operating level ― the lowest level to which the reservoir is drawn down under normal operating conditions. Morning glory spillway ― see spillway. One-Hundred Year (100-Year) Exceedance Interval ― the flood magnitude expected to be equaled or exceeded on the average of once in 100 years. It may also be expressed as an exceedance frequency, i.e. a percent chance of being exceeded in any given year. Operation ― the administra on, management, and performance of maintenance activities necessary to keep a dam safe and functioning as planned. Outlet ― an opening through which watercan be freely discharged from a reservoir. Outlet gate ― a gate controlling the ou low of water from a reservoir. Overflow dam ― a dam designed to be overtopped. Parapet Wall ― a solid wall built along the top of a dam for ornament, for the safety of vehicles and pedestrians, or to prevent overtopping. Peak Flow ― the maximum instantaneous discharge that occurs during a flood. It coincides with the peak of a flood hydrograph. Pervious Zone ― a part of the crosssec on of an embankment dam comprising material of high permeability. Phreatic Surface ― the top most flow line in an embankment dam. Piezometer ― an instrument for measuring pore water pressure within soil, rock, or concrete. Piping ― the progressive development of internal erosion by seepage, appearing downstream as a hole or seam discharging water that contains soil particles. Pore Pressure ― the inters al pressure of water within a mass of soil, rock, or concrete. Pressure Cell ― an instrument for measuring pressure within a mass of soil, rock, or concrete or at an interface between one and the other. Pressure Relief Pipes ― Pipes used to relieve upli or pore water pressure in a dam‘s foundation or structure. Primary Spillway (Principal Spillway) ― the principal or first-used spillway during flood flows. Probable Maximum Flood (PMF) ― a flood that would result from the most severe combina on of critical meteorologic and hydrologic conditions possible in the region. Probable Maximum Precipitation (PMP) ― the maximum amount and dura on of precipitation that can be expected to occur on a drainage basin. 287 O&M Manual of Malankara Dam August 2020 Program ― any authorized ac vity used to implement and carry out goals, ac ons, and objectives contained within the authorizing legislation. Program Life ― the period in a contract, conserva on plan, or plan during which the conserva on practice or conservation system shall be maintained and used for the intended purpose; determined by program requirements. Pumped storage reservoir ― a reservoir filled en rely or mainly with water pumped from outside its natural drainage area. Radial gate (Tainter gate) ― a gate with a curved upstream plate and radial arms hinged to piers or other supporting structures. Regulating dam ― a dam impounding a reservoir from which water is released to regulate Rehabilitation ― the comple on of all work necessary to extend the service life of the prac ce or component and meet applicable safety and performance standards. Relief well ― ver cal wells or boreholes, constructed downstream of an embankment dam to relieve the pressure from confined pervious layers in foundation overlaid by an impervious layer to arrest boiling. Repair ― ac ons to restore deteriorated, damaged, or failed dam or its component to an acceptable by meeting functional condition. Replacement ― the removal of a structure or component and installa on of a similar, func onal structure or component. Reservoir area ― the surface area of a reservoir when filled to controlled retention level. Reservoir routing ― the computa on by which the interrelated effects of the inflow hydrograph, reservoir storage, and discharge from the reservoir are evaluated. Reservoir surface ― the surface of a reservoir at any level. Riprap ― a layer of large stones, broken rock, or precast blocks placed randomly on the upstream slope of an embankment dam, on a reservoir shore, or on the sides of a channel as a protection against wave action. Large riprap is sometimes referred to as armoring. Risk assessment ― as applied to dam safety, the process of iden fying the likelihood and consequences of dam failure to provide the basis for informed decisions on a course of action. Rock fill dam ― an embankment dam in which more than 50 percent of the total volume comprises compacted or dumped pervious natural or crushed rock. Rock fill Dam ― see embankment dam. Roll Crete or Roller-Compacted Concrete - a no-slump concrete that can behauled in dump trucks, spread with a bulldozer or grader, and compacted with a vibratory roller. 288 O&M Manual of Malankara Dam August 2020 Rolled fill dam ― an embankment dam of earth or rock in which the material is placed in layers and compacted using rollers or rolling equipment. Seepage ― the inters al movement of water that may take place through a dam, its foundation, or its abutments. Service Life ― the actual period a er construc on of a dam, during which the prac ce func ons adequately and safely with only routine maintenance; determined by on-site review. Service/Regulating gate (regulating valve) ― a gate or valve that operates under full pressure and flow to throttle and vary the rate of discharge. Shaft Spillway (Morning Glory Spillway) ― a ver cal or inclined sha into which flood water spills and then is conducted through, under, or around a dam by means of a conduit or tunnel. If the upper part of the shaft is splayed out and terminates in a circular horizontal weir, it is termed a bell mouth‖ or morning glory‖ spillway. Side Channel Spillway ― a spillway whose crest is roughly parallel to the channel immediately downstream of the spillway. Sill ― (a) A submerged structure across a river to control the water level upstream. (b) The crest of a spillway. (c) A horizontal gate seating, made of wood, stone, concrete or metal at the invert of any opening or gap in a structure, hence the expressions gate silland stop log sill. Siphon Spillway ― a spillway with one or more siphons built at crest level. This type of spillway is sometimes used for providing automatic surface-level regulation within narrow limits or when considerable discharge capacity is necessary within a short period. Slide gate (sluice gate) ― a gate that can be opened or closed by sliding it in suppor ng guides. Slope ― (a) the side of a hill or mountain. (b) The inclined face of a cutting or canal or embankment. (c) Inclination from the horizontal. In the United States, it is measured as the ratio of the number of units of horizontal distance to the number of corresponding units of vertical distance. The term is used in English for any inclination and is expressed as a percentage when the slope is gentle, in which case the term gradient is also used. Slope Protection ― the protec on of a slope against wave ac on or erosion. Sluiceway ― see low-level outlet. Spillway ― a structure over or through which flood flows are discharged. If the flow is controlled by gates, it is a controlled spillway; if the elevation of the spillway crest is the only control, it is an uncontrolled spillway. 289 O&M Manual of Malankara Dam August 2020 Spillway Channel (Spillway Tunnel) ― a channel or tunnel conveying water from the spillway to the river downstream. Stilling Basin ― a basin constructed to dissipate the energy of fast-flowing water, e.g., from a spillway or bottom outlet, and to protect the riverbed from erosion. Stop logs ― large logs or mber or steel beams placed on top of each other with their ends held in guides on each side of a channel or conduit providing a cheaper or easily handled temporary closure than a bulkhead gate. Storage ― the reten on of water or delay of runoff either by planned operation, as in a reservoir, or by temporary filling of overflow areas, as in the progression of a flood crest through a natural stream channel. Tail water Level ― the level of water in the tailrace at the nearest free surface to the turbine or in the discharge channel immediately downstream of the dam. Tailrace ― the tunnel, channel or conduit that conveys the discharge from the turbine to the river, hence the terms tailrace tunnel and tailrace canal. Toe of Dam ― the junc on of the downstream face of a dam with the ground surface, referred to as the downstream toe. For an embankment dam the junction of upstream face with ground surface is called the upstream toe. Top of Dam ― the eleva on of the uppermost surface of a dam, usually a road or walkway, excluding any parapet wall, railings, etc. Top Thickness (Top Width) ― the thickness or width of a dam at the level of the top of the dam. In general, ―thickness‖ is used for gravity and arch dams, ―width‖ for other dams. Transition Zone (Semi-pervious Zone) ― a part of the cross-section of a zonedembankment dam comprising material ofintermediate size between that of an imperviouszone and that of a permeable zone. Trash rack ― a screen located at an intake to prevent the ingress of debris. Tunnel ― a long underground excava on usually having a uniform cross-section.Types of tunnel include: headrace tunnel, pressure tunnel, collecting tunnel, diversion tunnel, power tunnel, tailrace tunnel, navigation tunnel, access tunnel, scour tunnel, draw-off tunnel, and spillway tunnel. Under seepage ― the inters al movement of water through a foundation. Uplift ― the upward pressure in the pores of a material (inters al pressure) or on the base of a structure. Upstream Blanket ― an impervious layer placed on the reservoir floor upstream of a dam. In case of an embankment dam, the blanket may be connected to the impermeable element in a dam. 290 O&M Manual of Malankara Dam August 2020 Upstream Blanket ― see blanket. Valve ― a device fi ed to a pipeline or orifice in which the closure member is either rotated or moved transversely or longitudinally in the waterway to control or stop the flow. Water stop ― a strip of metal, rubber or other material used to prevent leakage through joints between adjacent sections of concrete. Weir ― (a) a low dam or wall built across a stream to raise the upstream water level, called fixed- crest weir when uncontrolled. (b) A structure built across a stream or channel for measuring flow, sometimes called a measuring weir or gauging weir. Types of weir include broad-crested weir, sharp- crested weir, drowned weir, and submerged weir. Zoned embankment dam ― an embankment dam composed of zones of materials selected for different degrees of porosity, permeability and density. 291