Altereo in Namibia
Feasibility study and detailed design to secure the drinking water production and transfer system for the Naute-Keetmanshoop area
The project took shape in 2016 following the visit to France of Namibia’s President, Dr. Hage Geingob, which brought together the Namibian authorities, the French Embassy in Namibia and Altereo to discuss the urgent water-related issues in the country including the networks ageing and the resurgence of leaks.
Thus, in January 2017, Altereo undertook a first mission in Namibia. The aim was to carry out a diagnosis of the main city’s water supply system, which turned out to be in very good condition. Altereo then carried out the diagnosis of another supply pipe in the Karas region, in the south of the country, which revealed, this time, significant intervention needs.
Water in Namibia
At the time of project design (in 2016), Namibia faces serious water problems. The country is experiencing its worst drought in 90 years with almost all the dams empty, except for the study area targeted by Altereo (in the South) precisely to preserve and optimise the resources that can still be mobilised.
To address this, Namibia is undertaking projects such as the creation of a second desalination plant on the coast, pulling a 350 km pipeline to Windhoek with more than 700 m of gradient to bring drinking water to Windhoek. These projects are colossal because of the state of emergency announced since February 2019. Residents must respect a number of instructions, such as not watering their garden or washing their car.
The price of water is also very high for the country: €2.50 per m³. This is not far from the French rates, knowing that the Namibian minimum wage is around 50 €/month.
Mission objectives
Several prospective missions were conducted by Altereo in Namibia in order to identify high-priority areas namely the Karas region and its capital, Keetmanshoop.
It was therefore decided to include in the Keetmanshoop municipality project:
- the technical rehabilitation studies of the conveyance pipeline from Naute dam
- the diagnosis of the distribution system involving significative improvement of the network, creation of a geographic information system (GIS), leak detection campaigns and an asset replacement program
- a master plan defining the works to be implemented up to year 2040
Mission description
Mission A: Diagnosis of the conveyance system
Replacement of the conveyance pipeline
Data collection was carried out through GPS and drone surveys to locate the 109 manholes and produce a high precision aerial photographic report (100 m wide) along the 45 km of existing pipeline as well as a Digital Terrain Model.
Since 2009, 68 leaks have been recorded on this pipeline.
A leak record form was created with the KIS® Collect mobile application. A tender was prepared and delivered to the client to renew the pipeline : technical drawings, phasing of works, costs, etc.
Diagnosis of the conveyance facilities: treatment plant, pumping stations and reservoirs
A panel of experts was involved in auditing the existing facilities, establishing detailed diagnoses and providing suggestions through costed rehabilitation works taking into consideration the 2040 master plan for the municipality.
Characteristics of the pipe
The pipeline runs 45 km between the dam and the town of Keetmanshoop. The route includes 3 pumping stations, a dam, a treatment plant and some reservoirs. The pipeline is made of 400 mm diameter steel and dates from 1971. It was a very well laid pipe at the time, but with a few errors in the route where some sections were not buried but laid on the ground.
Optimisation of remote management of conveyance structures
A global analysis was undertaken on the existing monitoring equipment: SCADA (Supervisory Control and Data Acquisition), level sensors, pressure gauge, flowmeters, etc.
Costed suggestions were provided to upgrade and ease the management of the existing facilities.
Mission B: Diagnosis of the distribution system and preparation of a Master Plan
Installation of an asset management unit
Original drawings of the water network were converted and transfered to KIS, Altereo’s geographical information system before being updated with the field investigations. A leak form was also created on the KIS Collect application and implemented within the municipality.
Diagnosis of the water distribution system: metrology, hydraulic modeling, night flow
A measurement campaign was perfomed on the Keetmanshoop water network via the analysis of bulk meters, pressure loggers and level sensors.
Night flow follow up enabled the estimation of the leaks and orientate localized and precise leak detection campaigns.
A hydraulic model was also constructed and calibrated to support the diagnosis and test the envisaged developments.
Pressure loggers have been installed throughout the network. Leaks and pressures were thus recorded.
The graph below shows a leak. The pressure drops completely and abruptly in a few hours.
Master plan 2040
The 2040 drinkable water master plan was established with the help of the diagnosis, the hydraulic model results and the optimized renewal program. It integrates the demographic growth and future water demand and aims to sustainably improve the service to the subscribers and preserve the water resource for the next 20 years.
Conclusions
Mission A: Diagnosis of the conveyance system
Overall, at least 6,994,000.00 € ex. VAT (~$N 112,839,000 ex. VAT) will be necessary for the renewal of the coveyance pipeline between Naute dam and the Keetmanshoop municipality. And 1,857,000 € ex. VAT (~ $N 29,950,000 Ex. VAT) for the rehabilitation of the treatment plant and the different reservoirs on the conveyance scheme (treatment plant reservoir, pumping stations reservoirs and Terminal resevoirs).
Mission B: Diagnosis of the distribution system and preparation of a Master Plan
State of the network at the beginning of the study
The yield was estimated to 50% on the municipal network. Taking into consideration the water purchases from NamWater, it represented in 2018, 120m³/h of leaks and a net loss of 1 million € ex. VAT ($N 16,000,000 ex. VAT) for the municipality.
Improvement of the network knowledge and Non-Revenue Water
Before Altereo’s intervention, about 22 km of pipes were unknown from the water services (material, diameter, depth, etc.) Today, the entire network is known and integrated in the GIS KIS®.
Moreover, following the installation of district meters on the water network and the execution of different measurement campaigns with the municipal teams, a reduction of more than 16% of the minimal night flow was observed between the beginning and the end of the study. It represents about 300,000 m3/year and therefore an annual economy of 280,000.00 € ex. VAT ($N 4,500,000.00 ex. VAT).
The master plan complements the operational improvement via better organisation of the services, training and assets replacement plan, etc.
Network replacement optimisation though targeting with the HpO® AI and 2040 master plan
HpO® analysed 260 leaks (881 pipes, 150 km). The HpO® IA was calibrated with leaks data over 4 year (2014-2017) and validated with 2 years of leaks data (2018-2019).
The failure risk forecast curve created by HpO®, shows that replacing 15% of the pipes would avoid almost 70% of the failures. This strategic replacement will save hundreds of thousands of euros to the municipality by 2040.
Overall, at least 6,500,000,00 € ex. VAT will be necessary to implement the master plan: current and future network consolidation, replacement program and training programs.