For improved system performance to meet the ever-growing customer needs, GWCL bolstered its policy of decentralization through the creation of the ATMA Production Region in 2003, to primarily focus on water production. However, with the evolving challenges in the water supply industry and GWCL’s need to continually re-strategize and reorganize, the region has been assigned additional responsibilities in recent years. Hitherto its formation, the production and distribution of potable water in the ATMA area was conjunctively managed by one management system.
The ATMA Production Region is the axis of GWCL’s production. It has a total designed capacity of 160 million gallons/day (MGD), representing 78% of GWCL’s total designed capacity of 204.9MGD nationwide. It supplies water to the Accra West Region, the Accra East Region, the Tema Region and parts of the Eastern Region, to over three (3) million people and most of the biggest industries in the ATMA area. The region operates with a staff strength of about 215 persons.
The Region has been mandated to execute the following:
- Potable water production
- Bulk water Transmission
- Distribution water quality management
The composition of the region includes the Weija Treatment Plant, the Kpong Treatment Plant, the Keseve Treatment Plant, Booster Stations at Tema, Dodowa and Accra, The Pipeline Maintenance Team, the ATMA Control Room and the Central Laboratory.
Weija Treatment Plant
This treatment facility is located at about 4km off the Accra-Winneba road. It was the first treatment plant in Gold Coast, constructed in 1914 with an initial capacity of 1,000,000 gallons/day (1MGD). Due to the growing water demand in the ATMA Region, the plant has metamorphosed through multiple expansion phases to a current design capacity of 54.2 MGD.
The plant utilizes the Densu River, dammed at Weija, as its source water and has three independent treatment systems, namely the Candy, Bamag and Adam Clark. The Weija Dam has a depth of 50ft (15.2m), a surface area of 8,300 acres, a storage capacity of 115*106 m3 and five spillway gates for occasional spilling when water level rises beyond 47ft.
The Densu River is the most polluted river of economic importance in Ghana, mainly due to domestic and agricultural activities along the river basin. Thus, the nutrients from these anthropogenic activities have culminated in the source water being significantly eutrophic. In line with the company’s vision of producing potable water of high standard, treatment at Weija involves an extensive multiple barrier approach which spans through the unit processes of screening, aeration, coagulation/flocculation, clarification, powdered activated carbon adsorption (optional), filtration, disinfection and pH adjustment.
Despite its heavy treatment chemical usage, Weija is the most economical system in the ATMA Production Region, solely due to its distinctive location (situated over 100m above sea level) that allows gravity distribution of treated water. Areas supplied by Weija include the western part of Accra (e.g. Korle-Bu, Dansoman, Accra Central, Darkuman, Sowutuom, Achimota, Mallam, Bortianor) and Kasoa in the Central Region.
Kpong Treatment Plant
This plant was constructed in the 1950s. It is located 54 kilometers North-East of Tema, and consists of the Old Works (i.e. the Candy, Tahal and Siemens plants), the New Works, and the China-Gezhouba plants. Currently, it is the biggest treatment plant in Ghana with a collective design capacity of 101.2 MGD.
It gets its source water from the Volta Lake, about 17km downstream of the Akosombo Dam. Processes of treatment are similar to that of Weija, except for the conspicuous absence of the coagulation/flocculation stage due to the good physico-chemical properties of the raw water. However, with the advent of climate change and increased anthropogenic activities, the plant has occasionally employed alum coagulation when extensive run-offs deteriorate the raw water quality.
Typical areas of supply include the following: Tema Region, Accra East Region, and some rural parts of the Eastern Region.
Keseve Treatment Plant
This is a very small plant of a capacity of 0.3 MGD, located at Ada. Like Kpong, its raw water source is the Volta Lake, and thus employs same treatment mechanism as that of Kpong. Areas supplied by the plant includes Ada and some parts of the Volta Region.
The region has 3No. booster stations ¾ Tema Booster, Dodowa Booster and Accra Booster stations. The Tema Booster station is fed by high-lift pumps from the Kpong New Works via a 1,050 mm (42”) pipeline into three terminal reservoirs of capacities 0.75 MGD, 2.5 MGD and 10 MGD. Areas served by the Tema Booster station includes Tema township, Ashaiman, Kpone and its immediate surroundings, and the Accra Booster Station.
The Dodowa Booster station receives water from the China-Gezhouba plant at Kpong via a 1,200 mm pipeline into a reservoir of a capacity of 6.6 MGD. It serves the surrounding communities in the Accra East Region and feeds the Accra Booster station as well.
The Accra Booster station receives water from Tema Booster via 32” pipeline and a 36” pipeline from Dodowa Booster. It serves different pressure zones within the Accra East Region.
Pipeline Maintenance Team
This team is responsible for the maintenance of the bulk water transmission mains. They are a mobile team responsible for maintaining all bursts and leakages on major transmission mains in the region. Some of these include the 54 km 1,050 mm (42”) steel main which feeds the Tema Booster station from Kpong New works; the 22.5 km 800 mm diameter (32”) steel main interconnecting the Tema and Accra Booster stations; the 1,200mm (48”) from Kpong China-Gezhouba which feeds the Dodowa Terminal Reservoir; and the 48”/36” mains that feed the Accra Terminal Reservoir from that of Dodowa; the two 1,200mm (36”) steel mains that connect Weija and Western Accra; the 16”, 21” and 28” from the Weija Candy/Bamag plants, among many others.
Breaches in the hydraulic and physical integrity of pipelines can cause a significant deterioration of water quality. To help monitor distribution water quality in the distribution regions, the Central Laboratory conducts routine water quality sampling exercises to evaluate the status of the physico-chemical and bacteriological quality of the water to ensure conformity to set standards. The laboratory is also involved in some specialized consultancy services including pipeline and reservoir disinfection, chemical purity analysis, sieve analysis on filter media, water quality testing as well as treatability and simulation test for new projects.