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OWERRI WATER SCHEME

 

OWERRI WATER SCHEME


The Owerri Water Scheme draws its raw water from Otamiri River started to function in 1985 but was officially commissioned in May 1988. The Regional Water Scheme was designed to supply over 40,000 cubic meters of water to a population of over 300,000 residents by 1985.

Its main Objective was to improve the organoleptic (Limpidity, color, smell and taste), chemical and physical (PH, hardness, conductivity, solids in suspension, iron, manganese), bacteriological (fecal contamination) features of the water until it was made drinkable. The plant therefore was designed to subject the raw water to successive series of various treatments, each one made in a single plant section with specific and defined aim.

Intake Work

The river is dammed to house the intake works- An embankment or Earth dam to divert raw water from the river into the low lift pumping station.

Low Lift Pumping Station

Consists of an underground water sump of 19.5 x6.1x4.2 meters deep and provides 499 cubic meters of water divided in two sections intercommunicating but separable through sluice valves. There is a water level gauge that indicates the water level in the underground tank.

Aeration Basin

The objective in this section is to eliminate unpleasant flavors and smells, remove most of dissolved carbon (IV) oxide and oxidant iron and manganese constituents, equally aimed is the oxygenizing of the water.

Flocculation Basin

This is divided into 2 parts; 1. Rapid mixing in which an aluminum sulphate solution is added together with sodium carbonate solution. 2. The second section is for “slow mixing” of the chemical to achieve formation of flocks. This section requires rehabilitation to restore its objective.

Chemical Building

The building houses a warehouse for storage of chemicals and preparation of the solutions. The dosing pumps and dissolution tanks are equally housed here.

Sedimentation Basin

Sedimentation Basin aims at clarifying water

Chlorination Building

This houses tone chlorine cylinders with chlorinators. The section requires massive modernization to include the use of UV rays and chlorine dioxide.

Filtration Basins

There are four beds with four layers of filter media of different coefficient and sizes. They cover the nozzles. This section requires complete rehabilitation in order to achieve effective filtration and reduce turbidity to 0-1 NTU.

High Lift Pumping Station

There is an underground tank of 4370m3 capacity here. There are provisions for 5nos vertical centrifugal pumps with a nominal capacity of 880m3/hr which pumps water to the elevated storage tank of 50 meters high. Equally installed here are 2 vertical centrifugal pumps of 190m3/hr which pumps treated water to the back wash tank.

There are two power station located at the low high lift stations. These supply electrical energy for the operation of the treatment plant. The electric generators are supposed to serve as standby energy sources. However, due to inadequate public power supply the generators are always in use and diesel consumption is prohibitive. It is recommended that the construction of a small hydropower station fully dedicated to this plant will solve its energy problem and thus make water available to the capital city and its immediate environs.

Conclusion and Proposal

A. Complete overhaul of all sections including upgrading of the laboratory.
B. Upgrading and increasing the water piping network through which water is delivered to the inhabitants including metering with prepaid meters to households. This will include survey, design and construction.
C. Expansion of an entirely new water treatment plant to double the amount of portable water available to about a million people.