ENV4203 Public Health Engineering Assessment 1 Task | UniSQ

ENV4203 Special instructions: 

Information provided is generally adequate; if any assumptions are made, these should be clearly stated giving your reasons/justifications. 

A small coastal town in Queensland is subject to an increasing permanent population and also a transient influx of tourists during the summer period. Council already receives frequent complaints of restricted water supply. The water supply system comprises a rising trunk main from the treatment plant A to the service reservoir B, the service reservoir, and service mains to the consumption areas. Two consumption areas C and D at different elevations are gravity supplied from the service reservoir. The service reservoir has a capacity (total storage) of 15ML and is fed through the rising trunk main from the water treatment plant located 5 km away. The static lift between the water treatment plant and reservoir is 40 m. Other relevant information is shown in the sketch below.

You are provided with data on the population and consumption as follows: 

A.The present rising main is unable to meet the water demand and frequently breaks down. Council proposes to quickly replace the rising main. Select a suitable pipe diameter that will meet present and the future maximum population demand. Assume MDMM=1.5 x AD. The pumps for the rising main are restricted to operate not more than 20 hours a day. Once designed, estimate the pump power required for the present and future population for both scenarios of flow rate. It is assumed that minor losses between the water treatment plant clear-water tank outlet and service reservoir are negligible and may be ignored. The design lifetime of the rising main is considered to be 30 years.

B. The ground elevations at area C vary between 15 RL and 30 RL, and that in area D vary between 12 m RL and 20 m RL. The Queensland Guidelines for planning and Design of Urban Water Supply Schemes require the minimum allowable pressure in reticulation or service mains to be 22 m head. Other provisions of the Guidelines referred to in the study material are also to be considered. Minor loss in the service mains is estimated to be 1.5 times the velocity head. You are required to investigate and report to the Council what population is adequately served by the existing service trunk mains. Then calculate and comment on the immediate and future shortfall of population served (if any). 

C. Assume that the service reservoir operating storage is 30% of the peak day demand; the required fire storage is 20 L/s for 4 hours and the breakdown provision is 1 peak day demand. Find out what population can be adequately served by the existing service reservoir and comment on the immediate and future shortfall of population served (if any).

ENV4203 Assignment 1: Design of a water Supply Scheme Marking scheme: