6.1

A water district that serves a suburban community needs a new water transmission main from an existing reservoir. The line will be 5.1 miles long. The reservoir elevation is +280 feet, and the elevation at the final discharge point a non-pressurized storage tank in town is +100 feet. No pumping will be provided. It is proposed to build a single line of new, smooth, clean, cast iron pipe. The Darcy friction factor is assumed to be 0.021. The present demand is 1 mgd.

1. The smallest appropriate commercially available pipe size for the line is

   1. 6 in.

   2. 8 in.

   3. 10 in.

   4. 12 in.

2. Is the initially assumed value for f appropriate?

   1. The initial value for f is too small.

   2. The initial value for f is appropriate.

   3. The initial value for f is too large.

   4. The appropriateness of f cannot be determined from the available data.

3. The Manning n which could apply to this new line is nearest to

   1. 0.010

   2. 0.012

   3. 0.014

   4. 0.016

6.2

The pipeline installation shown in Exhibit 6.2 is used to fill trucks with water. The 25-cm line is 30 m long; the 15-cm line, A, is 3 m long; the 15-cm line, B, is 15 m long. The Darcy-Wiesbach friction factor f is 0.02. Neglect minor losses.

Exhibit 6.2

When all gate valves are fully open, the total discharge that can be delivered by the system is most nearly

1. 0.35 m ³/sec

2. 0.40 m ³