1- INTRODUCTION2- DEFFINITION OF THE PROBLEM
The study area is situated on approximately 0.85 square km. of land located 6 km to the North of Ramallah City and is inhabited by 6400 inhabitants. In 1980 a water network was installed using galvanized pipes for diameters 2” and less and steel pipes with internal cement lining and external asphalt coating for diameters greater than 2”. The bad condition of the open sewage collection system resulted in increasing the corossivity of the soil and accelerated the deterioration of the network.
The crowded conditions in the study area, the large variations in the topography, the large inlet pressure and the condition of the sewage collection system all contributed to the following: -
I- Over 50% of the network is subjected to pressures ranging from10 bar to 16 bars.3- INVESTIGATIONS MADE
II- Over 60% of the galvanized network and house connections are badly coroded.
III- A large difference in the average daily water billed (322 m3) and what is registerd at the inlet connection (520 m3) indicated the existance of a serious problem, which need to be solved.
IV- Large number reported of bursts due to corroded pipes (20 in 1998) compared to the length of the network (6.56 Km.)
Using the BABE software, JWU conducted an investigation for the amount of leakage from the network. It consisted of measuring the inflow and pressure at the inlet connection and the pressure at the point of AZNP (average zone night pressure) and target point over 24 hours. All the data was incorporated into BABE software and results for the expected amount of leakage, usage, and total inflow were obtained.
4- RESULTS OF INVESTIGATION
The results of the investigation showed that the difference between the total amount of water, which entered the system, and the estimated use was 103.2 m3. This amount is associated mainly with leakage from the network and was purely theoretical.
In order to deal with the problem, the pressure at the inlet was reduced (using pressure control valve) by 23 meters and another set of readings were taken at the same points for the pressure and flow. This reduction resulted in reducing the leakage from 103.2 m3/day to 85.8 m3/day thus realizing a saving of 17.4 m3/day while maintaining the same amount of usage.
5- SOLUTIONS PROPOSED
In light of the water savings achieved at a reasonably low reduction of pressure at the inlet connection and without actual pressure management of the system, it was proposed to do the following: -
6- RESULTS OF IMPLEMENTATION AND LOSS REDUCTION
- To install a permanent pressure control valve at the inlet connection in order to reduce the inlet pressure to 130 meters (otherwise water will not reach the target point). The total cost of the proposed system was (USD) 6200.00
- To sector the study area into two zones in order to reduce the difference in elevation between low points and high points
The following is the result of installing the pressure control system at the inlet connection.
|The saving in water in one year is
|The marginal cost of 1m3 of water is
|Total value of water saved / year
|Costs of material & labor
||$ 6200 |
|Pay back period