Ongoing Sub Projects

Contract No. : MCUDP/SLLRDC/W/19

Contractor : E & C Komuthi JV

Contract Value : Rs. 344.577,482.70

Date of Commencement : 11.01.2017

Anticipated Completion Date : 31.01.2021

It is proposed to construct bank protection works and remove bottle necks along the Madiwela East Diversion Canal at the tail end, in order to maintain required conveyance throughout the canal.

Main scope of this sub project includes ;

~Rehabilitation of the flap gates of the existing main flood gate structure.

~Construction of new flood gate structure, and fabrication of new gates for secondary canal.

~Bank protection works.

~O & M Road and side drains.

~Raising of water mains owned by NWS&DB and construction of new pipe supporting structure.

~Removal of gated structure owned by Irrigation Department, which acts as a major bottleneck to flow.

~Opening of an additional bay of Low Level Road Bridge.

Contract No. : MCUDP/SLLRDC/W/12

Contractor : China Geo Engineering Corporation

Contract Value : USD 9,766,653.08 + LKR 473,212,403.68

Date of Commencement : 01.06.2017

Anticipated Completion Date : 31.03.2021

It is proposed to construct a storm water pumping station at Nagalagam Street, across St. Sebastian North canal, in order to mitigate the floods by pumping flood water into Kelani River during periods of high water levels in Kelani River and high rainfall in Metro Colombo Basin.

The capacity of this pumping station is 30 m3/s, which comprises of 5 Nos. of 6m3/s pumps.

Main scope of this sub project includes ;

~Construction of gate structure and fixing of new vertical gates.

~Removal of existing structure which acts as a major bottle neck to flow.

~Construction of new pumping station and installation of pumps with screens and other mentioned equipment.

~Bank protection works.

~Dredging of canal.

Contract No. : MCUDP/SLLRDC/W/14

Contractor : M/s. China Petroleum Pipeline Engineering

  Company Ltd

Contract value : 32,098,189 USD & Rs. 246,060,603.00

Date of Commencement : 30.05.2018

Anticipated Completion Date : 31.08.2021

It is proposed to construct two underground tunnels, one is in Mutwal area and other one is in Torrington area in order to mitigate floods by introducing new outfalls to the sea.

New Mutwal Tunnel is 3 m in diameter and 700 m long, starts from the Main Drain and discharges the water to sea at Mutwal area. The capacity through the tunnel is 15 m3/s.

Torrington Tunnel, which collects water from Thummulla and surrounding area, discharges to the sea at Bambalapitiya. The diameter of Main Tunnel is 3 m and there is a network of spine and lateral tunnels (1.2 m – 2 m diameter) which collects water from surrounding area and feeds to the Main Tunnel.

Main scope of this sub project includes,

~Construction of inlet channel

~Construction of receiving shaft

~Construction of outlet channel

~Tunnel boring

~Construction of man holes

Contract No. : MCUDP/SLLRDC/W/24

Contractor : Salcon Engineering Berhad

Contract value : USD 5.85 Mn + LKR 1,181.53 Mn

Date of Commencement : 03.09.2018

Anticipated Completion Date : 31.03.2021

It is proposed to construct a storm water pumping station at Ambathale Flood Bund, across Madiwela East Diversion Canal, in order to mitigate the floods by pumping flood water into Kelani River during periods of high water level in Kelani River and high rainfall in Colombo basin.

The capacity of this pumping station is 20 m3/s, comprising of 5 Nos. of 4m3/s pumps.

Main scope of this sub project includes ;

~Fixing of new vertical gates to the existing gate structure.

~Construction of new pumping station and installation of pumps with screens and other electro-mechanical equipment.

~Bank protection works.

Contract No. : MCUDP/SLLRDC/W/16A

Contractor : E&C RR JV

Contract Value : Rs. 859,487,036.93

Date of Commencement : 01.02.2019

Anticipated Completion Date : 31.01.2021

Stage I of this scheme is the canal stretch parallel to Gothatuwa Flood bund and it has a length of 270m. It is proposed to improve the existing canal stretch to a bed width of 10m and bed level of -1.0m MSL. The proposed left bank (Gothatuwa bund side) will consist of an earthen section with a 1:1.5 side slope, up to 2.0m MSL top level. In the right bank, it is proposed to construct gabion wall having a +2.0m MSL top level. In addition, it is proposed to construct a 4.5m wide Operation & Maintenance (O&M) road at +2.0m MSL level, with side drain adjacent to right bank gabion wall. This road will start from the existing by-Road connecting Kolonnawa-Gothatuwa Road and Low-Level Road.

It is proposed to construct a connection box drain having a width of 15m and -1.0m MSL bed level, across Gothatuwa bund and underneath the existing Kolonnawa-Gothatuwa Main Road. Three vertical gates, each of 5.0m x 3.5m is proposed to be provided at Kittampahuwa Canal side. Under normal conditions, the flood gates will be kept closed, hence separating the catchments and allowing no trans-basin flow. During flood situations, the gates will be opened, allowing the flow of excess flood water from one side to the other, depending on the flood conditions. It is also proposed to have provisions to operate these floodgates as part of the upcoming Real-Time Control (RTC) System for flood mitigation in Colombo.

Contract No. : MCUDP/SLLRDC/W/16D

Contractor : E&C RR JV

Contract Value : Rs. 1,431,682,105.43

Date of Commencement : 01.02.2019

Anticipated Completion Date : 31.05.2021

Stage IV of this scheme is the canal stretch parallel to the Railway track and in proximity to Orugodawatte storage premises of Ceylon Petroleum Corporation (CPC). This section is having a length of 1,080m and confluences with Kelani River near Kalu Palama by crossing gate structure of Irrigation Department at Sedawatte – Ambatale Road.

It is proposed to improve the existing Kittampahuwa Canal in this section as a trapezoidal section of 18m bed width, keeping a constant bed level of -2.0m MSL. Right bank will be provided with steel sheet pile and gabion bank protection walls with an O & M road.

There are two existing gate structures, i.e. CPC gate near CPC premises and Irrigation Department gate near Kalu Palama. These structures have been identified as bottlenecks and they are proposed to be improved. The existing bridge at Sedawatte – Ambathale Road near Kalu Palama is proposed to be removed and replaced with a bridge of 18m span. A new gated structure protecting up to +5.0mMSL with three vertical gates (6.0m x 4.5m) will be constructed downstream of above bridge to prevent Kelani flood water entering to the canal. There are few secondary canals connections to the main canal at both banks of Kittampahuwa main canal. They are proposed to be connected to the main canal through drop structures.

Contract No. : MCUDP/SLLRDC/W/13

Contractor : China Geo-Engineering Corporation

Contract Value : USD 5,934,884.90 + LKR 165,833,566.49

Date of Commencement : 01.02.2019

Anticipated Completion Date : 31.05.2021

It is proposed to construct a storm water pumping station at Technical Junction, Maradana across St. Sebastian South Canal, in order to mitigate the floods by pumping flood water from the canal into Beira Lake during periods of high rainfall in Colombo Basin.

The capacity of this pumping station is 10 m3/s, comprising of 2 Nos. of 5m3/s pumps.

Main scope of this sub project includes ;

~Rehabilitation of existing gates.

~Construction of new pumping station and installation of pumps with screens and other mentioned equipment.

~Bank protection works.

~Dredging of canal.

Contract No. : MCUDP/SLLRDC/W/20

Contractor : DGES-RR-INDOEAST JV

Contract Value : LKR 609,618,238.99

Date of Commencement : 01.03.2019

Anticipated Completion Date : 31.12.2020

Most of the canals in the northern part of Colombo canal system are heavily polluted, especially during the dry season. Therefore, it is proposed to flush this part of the system during the dry season using fresh water pumped from Kelani River.

In order to isolate the polluted part of the system, three gates will be constructed at; (1) Yakbedda Bridge (Kolonnawa Canal), (2) Sri Jayawardenepura Mawatha Bridge (Heen Ela Canal), and (3) Port Access Road Culvert (Main Drain).

After closing the above gates and also the gate that is to be constructed under St. Sebastian North Lock Gates and Pumping Station (NLPST) Project (St. Sebastian North Canal), water will be pumped from the river using the reverse pumping facility of NLPST, and the system will be flushed by opening the gates at Main Drain and St. Sebastian North Canal.

Contract No. : MCUDP/SLLRDC/W/18

Engineers Estimate : Rs. 414 Mn

Expected Date of Commencement : July 2017

Anticipated Completion Date : June 2021

Background

In 2012 the World Bank and the Government of Sri Lanka (GoSL) agreed upon a loan to support the government to reduce flooding in the Colombo Water basin under project termed Metro Colombo Urban Development Project (MCUDP). Flood control measures include construction of two micro tunnels, establishment of three pumping stations to facilitate rapid discharge from the Colombo drainage canal system, widening of existing drainage canals and construction of control gates to compartmentalize flood prone areas to reduce flood risk. Under the project, establishment of a real time control center has been proposed to operate the flood control facilities considering the rainfall conditions and the flooding potential. With the new Megapolis Development Plan the scope of the RTC was revised in view of the need to assess short-term and long-term flood risks for Metro Colombo to safeguard investment and ensure sustainable urban development. In addition to assisting and managing flood control, the center will provide environmental services and information for integrated water management in the city.

Objectives

Thus the objectives of the Real Time Control Center are defined as,

1.Develop an integrated flood control and water management information system

2.Provide early warning support for the Metro Colombo area

3.Develop optimal operational rules for the flood control facilities such as pumps and storage facilities considering also the potential storage and use water to make a pleasant urban environment.

4.Assess current and evolving future water related risks to Megapolis from urban development as well as climate change.

The Scope and activities

The following is a description of scope and the activities planned to achieve the above objectives;

1.Development of a rainfall data integration system, using existing sources such as satellite rainfall observations, numerical weather forecasts and observations from rain gauges

2.Setting up rainfall monitoring stations for the metro Colombo area

3.Setting up water level monitoring gauges in canals/rivers/ponds and establishment of canal flow measurement system

4.Establishing communication links from the monitoring devices to the flood control and water management center

5.Developing a flood forecasting system comprising of rainfall integration, hydrological forecast model, hydro-dynamic model for inundation forecasting.

6.Developing a decision support system using all inputs to calculate the best operation of gates and pumps and setting up a Scada control system for real time operation of the pumps

7.Establishment of a center for data integration, information dissemination and providing water management services for Metro Colombo

8.Setting up a system for continuous research and development to assess evolving risks due to urbanization and climate change and propose remedial measures.

System Implementation

The system consists of the following five components.

1.The Centre for Urban Water which is the physical infrastructure where monitoring and forecasting information is collected, analyzed and disseminated.

2.Modeling systems comprising of (a) Rainfall integration and forecasting (b) Hydrologic and Hydro-dynamic forecasting for the observed and forecasted rainfall and (c) Risk assessment and Operational procedures formulation.

3.Computational environment consisting of servers for modeling, information archiving and dissemination through a web based content management system. The computational environment is set up in a cloud platform.

4.Monitoring and control system consisting of rain gauges, water level gauges and Scada control units for facility operations which provide real time information to the center.

5.Stakeholder collaboration mechanism and outreach mechanisms.

Current Status

Monitoring

The first phase of real time monitoring sensor deployment has been started. Three types of devices, (a) weather stations that measure rainfall and other weather parameters (b) Rain gauges that measure only rainfalls and (c) water level sensors using both radar and ultra-sonic devices. The rain gauges are mainly placed at schools in the Kelani River basin and they will provide real time measurements to the RTC System. The schools will have priority access to RTC facilities for educational activities. The figure shows different installations that have already been done and the list of schools who have consented to become partners.

1.Urumewella School – Kegalle

2.Malabe Boys school – Malabe

3.Dikoya Sinhala school – Hatton

4.Vidya Pradeepa Junior School- Kithulgala

5.Waga Sri Rathanasara Maha Vidyalaya

6.Kottawa North Dharmapala School

7.Anula College –Colombo

8.Buwanekaba Maha Vidyalaya, Maharagama

9.Depanama Dharmapala Primary School

10.Kotuwila Gamini Vidyalaya

11.Ediriweera Sarathchandra School, Mulleriyawa

12.Sri Rahula Maha Vidyalaya, Madiwela

13.Somadevi Girls College, Kotikawatta

14.Joseph’s College, Colombo 01

15.Lawrence’s Convent, Colombo 06

16.Andrews College, Mutwall

17.Thurstan College, Colombo 07

Three inundation (flooding) simulation models are now available at RTC. They have spatial resolution of 250m x 250m, 150m x 150m and 30m x 30m. The coarse models (250m and 150m grid size) are extremely fast and are used to model whole lower Kelani basin from Glencourse station downwards. They are used for operational forecasts every day. The 30 m model covers only Colombo and use the boundary conditions from other models. It is used for forecasting when there is a threat of flooding in the city. Simulation results of 2017 May event from 250m, 150m and 30m grid resolutions are shown in the following figures and they are almost same as the observed flood map prepared by Survey Department.

Currently a total of 16 Rain gauges and Weather stations have been deployed within Kelani River Basin to capture the rainfall distribution inside Kelani catchment. These gauges require regular maintenance to avoid any obstruction in data acquisition or data transmission to CUrW (Center of Urban Water) Database. Hence, frequent field visits are being carried out by RTC Research Engineers in order to investigate any obstructions caused to rain gauges and weather stations in field conditions. This will enable RTC to understand any probable issues that may be encountered at field in relation to sensors and communication modules. Figure below shows the locations of rain gauges and weather stations that have been deployed.

Internet of Things (IOT) enabled Water Level Gauges were tested and installed in Colombo canal system. These devices will allow RTC to obtain high precision real time water level data which will be utilized in flood monitoring and improving the reliability of flood forecasting system. Figure below shows the water level gauges that have been installed in Colombo area and their locations.

The following modeling systems have been developed and are at various stages of calibration and finalization

1.Satellite rainfall data feeds at hourly intervals are received and integrated. The process is automated.

2.Weather forecast system for three-day forecasts at 3km resolution for the country is established and automated.

3.Real time data assimilation platform with both temporal and spatial databases completed.

4.Hydrological model has been established and verified

5.Operational hydro-dynamic models (250m and 150m resolution) have been established and verified. Detailed inundation modeling system (at 30m resolution) is now complete and used once alerts are triggered.

6.On risk assessment, building foot print of the city now completed and damage estimation for potential structural flood damage (pre-disaster damage estimation) is completed. Exposure mapping will be carried out in the near future to assess economic vulnerability. Possible evacuation locations and people at risk for different flood frequencies have been established.

The computational environment is already established in Google Cloud. Rainfall data integration to hydrological and hydrodynamic modeling and processes are linked and automated and the main workflow framework is now completed.

Pls. LINK with Metro Colombo Urban Development Project’s Web site – https://mcudp.lk