Question

Data from field investigation:

• The survey conducted by getting information from various sources including the statistical records in the respective ministries, municipality and mukhtars has resulted in a population figure of 85,600 persons at present residing in the town under design. Review of the previous statistics has shown that the average yearly rate at which the population has been steadily increasing is 1.75%.
• Further investigations from neighboring communities that lead similar sociological conditions and considering the water demanded by the existing and possible future industrial and commercial organizations has indicated that a supply of 250 L/person/day would be ample to cover all the needs of the community.
• As for the available sources of supply, it was determined that the most suitable source is that of a lake formed of an impounding reservoir that is present within reasonable distance from the town.  This lake is located about 3km from the town at an elevation of 363m above seawater level while the town elevation is at 324m. Records show that the level of the water in the lake varies between the maximum winter level and the minimum summer level by 4m while maintaining a minimum water depth of 4 m.
• The quality of the water in the lake varies appreciably between the four seasons, whereby during the fall and winter seasons the turbidity of the water builds up to 275 mg/L, while during the spring and summer the turbidity drops down to less than 10 mg/L. No toxic impurities were detected in the water, besides the water is relatively soft with low concentrations of Ca and Mg. Limited concentration of microorganisms were detected but not of major importance.
• A survey on the site for the treatment plant resulted in selecting a site, with a reasonable cost, of an area of 3000 m2 that is located at about 1000 meters away from the lake at an elevation of 330 m.

• Determine the design period and design population.
• Determine the design quantity of water that is to be treated taking into consideration the water that could be lost under various operations in the treatment process to be estimated at 6%.
• Determine the type of treatment that to be adopted.
• Determine the components of the treatment plant
• Determine the design criteria for each component. The expected operating temperature is 25˚C.
• Determine a preliminary cost estimate for the plant (refer to the internet on cost estimate of (type) water treatment per cubic meter).

Answer 1