HYDRAULICS AND ENGINEERING APPLICATIONS Coursework Brief

Brief

Wessex Water is to supply the new development of 2000 houses in Poundbury with drinking

water. It has been determined that a pumping station (PS) at Burton will supply water from

the regional main to a service reservoir (SR) at Lambert’s Hill, which in turn will allow water to

flow by gravity to the urban development. There are therefore two pipes that need to be

designed, the pumped trunk main from Burton PS to Lambert’s Hill SR, and the gravity

distribution main from Lambert’s Hill SR to Poundbury. You are tasked with coming up with

different solutions, and outlining the most cost effective solutions; your designs will

encompass the route, pipe material, pipe diameter and, for the trunk main, the outline pump

arrangement. You will also advise on the need for pressure surge protection.

 

The pipeline’s route will be governed by several factors, amongst them system hydraulics

(ground elevation and slope), land use (landowners, road / rail and river crossings), sensitive

areas (AONB, CWS, SSSI, SAM) and access (construction and maintenance). The pipeline’s

diameter will be governed by system hydraulics (pressure, flow, friction, length) and the

material will be governed by ground conditions and costs. Relevant requirements from the

Wessex Water Design Standards are given below (for more information please refer to the

full document on the module website):

1. General

• Trunk mains shall not be used to provide local supplies.

2. Design capacity

• Trunk mains shall be sized for peak week or maximum daily demand.

• Distribution mains shall be sized for the peak hourly demand based on the

maximum daily demand.

3. Design velocities

• Both minimum and maximum velocities shall be considered.

• The diameter / velocity shall be optimized for pumping mains by calculating

the 60-year whole life cost.

• The minimum velocity shall be based on the 12-hour retention time. The

maximum velocity shall be < 2.0 m/s for trunk mains and < 1.5 m/s for

distribution mains.

4. Hydraulic design

• Colebrook White (HR Wallingford look-up tables).

• Roughness values to allow for future deterioration.

 

5. Minimum pressure

• 6m anywhere along the pipe.

• Distribution mains must be >15m (design for 20 m).

6. Maximum pressure

• Where pressures in the distribution system are more than 35m, consideration

shall be given to the installation of Pressure Relief Valves (PRVs) (see section

13).

• The maximum pressure is limited to 16 bar in pumped trunk mains [e-mail

from Wessex Water].

7. Material

• DI (Ductile Iron) or PVC or both.

8. Crossings

• Major crossings (at railway lines, rivers and main roads) will require twin

pipes.

• Buried crossings preferred.

9. Swabbing chambers

• Every 2.5km or less.

10. Thrust blocks

• Required on bends / branches where pipelines are not continuous, or pipe

material does not possess adequate tensile strength.

11. Valves

• In-line valves every 2km or less.

• Air valves at high points.

12. Hydrants and washouts

• Washout valves at low points.

13. Pressure Relief Valves

• Shall be installed as required.

 

In evaluating the options, your report must:

• Use outline design to size appropriate pipes of appropriate materials.

• Address the costs and relative benefits of each scheme.

• Make a recommendation as to which scheme should be taken forward to detailed

design.

• Use performance curves to select pumps for duty / standby / assist operation.

 

• Advise of the need for pressure surge protection.

 

Format

Using 11-point Calibri font with 1.5 line spacing and 3cm margins, the text within the report

must not exceed 3000 words (~9 pages) in length. This limit applies to the main body of the

report (introduction to conclusions), excluding figures, graphs and tables. Below is a suggested

format for the report; the UWE generic marking scheme will be used to grade your reports

(see below).

• Title page – suitable heading identifying the subject of the report, plus the author’s

student number and date it was completed.

• Summary – brief description (~100 words) of the work that was undertaken and the

outcome i.e. the recommended pipe diameter, material, length and cost for both the

pumped and gravity main; it should have sufficient detail to allow someone to

determine whether the report will contain the information they require. The

Summary is a simplified combination of the Introduction and Conclusions; it will be

read first but written last.

• Contents – include section numbers as well as page numbers; it must include the

details of the appendices. Section and page numbering should start at the

introduction

1. Introduction – brief explanation of the design problem (the purpose of the report) to

include the specification being used, plus the report’s structure.

2. Investigations of route – explanation, assumptions

3. Options considered

a. Justification for selection of preferred pumped and gravity pipe routes.

b. Pipe design – explanation (including pipeline ancillaries such as Pressure Relief

Valves (PRVs), washout chambers, crossings etc), table of diameters and head-

losses from pipe and fittings, assumptions.

c. Costs – explanation, justification for selection of preferred material / diameter.

d. Pump – explanation, justification for selection of chosen Armstrong pump

arrangement.

e. Pressure surge – justification for recommendation of pressure surge analysis by

an expert consultant

4. Conclusions – preferred options; further work may also be identified in this section.

 

5. References – UWE Harvard style referencing of every source used; a bibliography can

also be included to illustrate reading within the subject area.

• Appendices

A. Plans and long sections (including the Hydraulic Grade Line (HGL)) of all routes

considered.

B. Design calculations.

C. Cost spreadsheets.

D. Information relevant to pump selection.

E. Information relevant to pressure surge protection.

 

Generally

• Tables must be annotated with a number and title above, figures annotated with a

number and title below.

• Make reference to your figures, tables, and appendices within the text.

• Use an appropriate number of decimal places and always include units.

• Avoid the word ‘then’.

• Do not abbreviate words (e.g., don’t).

• Write in the 3rd person.

• Use MS Word’s spelling and grammar checking feature.

• Full page, landscape tables and figures must be rotated anticlockwise.

• Calculations must be neatly presented.

• Re-read everything to ensure it makes sense.