1. CE 3372 Water Systems Design
Water Distribution Systems, Network Systems

2. Water Distribution Systems
Outline
Review of Lecture 3
Water Distribution Systems
Network Systems

3. review Define Hydraulics What is the Energy Equation
Name some assumptions of the Energy Equation
Difference in EGL and HGL
2 Main types of Head Loss
3 types of head loss models

4. Water distribution Water Supply System Includes water supply Treatment
Facilities
Pumping facilities
Transmission lines
Local distribution network
What is a water supply system?

5. Water Supply system
Distribution network - Consists of items designed to convey potable water at adequate pressures and discharges
Pipes
Fittings
Valves
Other appurtenances
Why are adequate discharges necessary? To cover the range of flows due to the fluctuation in demand
Pressures? Necessary for firefighting, general service to residents, and economic considerations such as leakage and energy losses
The pipes/fittings/etc. will be entered into the model. Valves as minor losses.

6. DESIGN Who? Design Requirements? Design parameters and regulations?
Personnel within the water company
Engineers / Consultants
Design Requirements?
Pressure
Fire Flow
Potable water
Cost Efficient $$
Design parameters and regulations?
State board of health
Local city/county health departments
EPA, AWWA, ANSI
As an engineer, design of wds includes:
Design requirements : Pressure and fire flow!
estimating amount of water needed for service area
estimating average and maximum daily demand
FIRE FLOW REQUIREMENTS! Usually controlling criteria in design of dist piping and storage
amount of water req to fight a fire (even if only a few hours) puts a strain on system

7. Pressure
Pressures
Must be high enough to..
overcome head losses in the system.
But not too high to...
prevent damage to fittings and other appurtenances.
Pressure Zones – Set pressurized areas (min and max) within the system by storage, boosters, or pressure control valves.
Can also be due to varying pipe size and topography
May be generated to ensure reliability in meeting fluctuation demands.
System pressures are adapted to requirements.
Hilly areas – booster pumping
Minimum pressures vary state to state
Established by the state’s Health Department / other agency
Fire Marshall may establish additional requirements.
Pressure zones – provide min and max pressures in the zone (could be a set force main)
Boosters are pump stations within the distribution network used to maintain a minimum pressure
The minimum pressure(20 psi) is a safety requirement to prevent potential back flows from house fixtures, and still have enough energy to push water up three stories.
Average for residential 40-60psi

8. Fire flow Fire Flow Parameters
Each municipality establishes own parameters based on local cond.
Insurance Services Offices (ISO) - Most used “Guide for Determination of Required Fire Flow”
Recommends criteria for
Establishing insurance rates
Classifying mun. with reference to their fire defenses and physical cond.
F = required fire flow in gpm
C = coefficient related to the type of construction
A = total floor area in ft2 (excludes basements)
Fire flow tests
Before new projects get approved for construction by the fire marshals office.
Flow tests are performed to determine fire flow capacity and adequacy of system

9. Water supply system Hydraulic Characteristics Service Characteristics
Pressures and discharges are a functions of HC
Length
Size
Condition of pipe
Service Characteristics
Demand as it relates to:
Present and projected population
Economic base
Fire flow
Climate
Q=VA
Pv=nrt
Driving in a car in traffic is high pressure
Service and hydraulic changes – design must incorporate allowances for changes
Changes can be relocating or replacing existing water line, increase pipe sizes, etc.

10. WATER utility Water utility company Companies exist in two forms
…who is responsible for the water quality and operation of the distribution system.
Companies exist in two forms
public entity that
..“exists for the health, safety, and welfare of the public”
privately owned utility that
..provides water for profit

11. Water supply system Gravity Pump Pump with Storage Dependable
Source of supply must be located well above the city
High-pressure demand for fire-fighting may require pumper trucks
Pump
Least Desirable
Pressures vary substantially with variations in flow
Provides no reserve if power failure
Pump with Storage
Most common
Water supplied at approximately uniform rate
Flow in excess of consumption stored in elevated tanks

12. Pipe System Primary Mains (Arterial Mains)
Form basic structure of the system
Carry flow from pumping station to elevated storage tanks
Carry flow from elevated storage tanks to service areas
Laid out in interlocking loops
Mains not more than 1 km (3000 ft) apart
Valved at intervals of not more than 1.5 km (1 mile)
Smaller lines connecting to them are valved

13. Pipe System Secondary Lines
Form smaller loops within the primary main system
Run from one primary line to another
Spacings of 2 to 4 blocks
Provide large amounts of water for fire fighting with out excessive pressure loss

14. Pipe System Small distribution lines
Form a grid over the entire service area
Supply water to every user and fire hydrants –Connected to primary, secondary, or other small mains at both ends
Valved so the system can be shut down for repairs
Size may be dictated by fire flow except in residential areas with very large lots

15. Water SUPPLY system Water source (Main Supply) Treatment Facility
Lake
River
Aquifer
Treatment Facility
Treats and disinfects water
Meet water quality standards
Potable water
Transmission Lines
Convey water from source – treatment facility facility – network
Pumping Facilities
Provide energy to move water
Intermediate Storage Facilities
Stabilize line pressures
Reserve for peak demand periods
Provide storage for fire flow req.
Distribution Lines
Convey water from storage – service areas
Looped(grid) and Branched Layouts
Appurtenances
Fire Hydrants. Valves, auxiliary pumps, fittings
Water Source – Larger may have multiple sources
Lakes and Res located in outlying areas – less pollution + hope of larger runoff from catchments
Rivers – water’s extracted upstream of civilization
Min supply volume of water source MUST serve present AND projected demand
Int Storage Facilities
In times of high demand, pressure in the network is decreased
Low demand, pressure is increased
Water volume fluctuates from 40-70% daily (discounting fire flow storage)
Distribution Lines
Service areas include residential/commericial/industrial areas
Appurt
Valves allow system to isolate small service areas when repairs are needed

16. Water Use Systems
Spatial and temporal distribution in support of human habitation
Water supply/treatment/distribution
Waste water collection/treatment/discharge
Capacity is based on POPULATION served
hydraulic dominated designs
We briefly went over water use systems

17. Water Use AND DEMAND Water Use Water Demand Consumptive
Municipal
Agricultural
Industrial
Mining
Non-consumptive
Hydropower
Transportation
Recreation
Water Demand
Quantity that consumers use per unit of time
Ex: Mgpd
Depends on population, climate, industry and economic factors
Water demand is what you have to estimate as an engineer include FUTURE development

18. Water DEMAND Residential Commercial Industrial
Single-family, multi-family (apartments)
Water for drinking, landscape, swimming, fires, street cleaning, etc.
Usually two demand peaks (morning and evening)
Commercial
Motels, hotels, offices, shopping centers
Usually less peak demand and less varied than residential
Industrial
Chemical plants, food processing plants, mines
Water for fabrication, cooling, petroleum refining, etc.
Water use depends on type of industr.
Also the 3 main developments

19. Assigning Demand Assign demand using network models (links and nodes)
Network models contain nodes that represent a multitude of actual connections.
While conceptually possible to model to every single connection, it is discouraged because
Model is hard to maintain
Small errors may go unnoticed
The operation of any single connection is not well known.

20. Network Types Branch No circulation Has terminals and dead-ends
Water in dead-ends is stagnant
Disinfection residual
Corrosion

21. Network Types Grid/Loop Furnishes supply from more than one direction
Water circulates
Disinfection is more effective.
Water “age” in system is younger (fresher).
In case of water main break, fewer people are inconvenienced
It’s cost that prohibits

22. Network Types Loop vs. Branch during network failure
Every link in a branch system is a single point of failure that isolates all downstream nodes.
Not with loop, only main supply line is failed

23. Branched System Distribution networks are multi-path pipelines Node
Inflow = Outflow
Energy is unique value
Links
Head loss occurs along line path
Classic 3 reservoir example
One topological structure is branching
EGL along paths must coincide (physics).
Can’t have 2 diff energies at same time and space and have equilibrium.
Gives you independence of path

24. Branched System
Continuity at the node

25. Branched System Head loss in each pipe Common head at the node
Red is head loss. Green is common head. Same at node. Z’s are elevation head.
Applying continuity to balance flows and energy losses along path with requirement that at the point MUST be same value

26. Branched System 4 Equations, 4 unknowns Non-linear – solve by
Newton-Raphson/Quasi-Linearization
Quadratic unknown – can find solution in iterations
EPA implements this non-linear equation solving method (newton)
If interested read readings in one of the previous modules

27. Branched system
TWO RESERVOIR EXAMPLE – Refer to spreadsheet

28. Looped System
Looped system is an extension of branching where one or more pipes rejoin at a different node.
Module 3 – Readings – Hydraulics notes for an example.
It is good to scan through.
Network of that complexity is fair in EPANET for exam
Hand-calcs are not required.

29. Looped System Nodes: Links Inflow = Outflow Energy Unique
Head loss along pipe
Head loss in any loop is zero
LOOP
Head loss at loop is zero.
Start at one node and go back, you have lost the head. It = 0
REVIEW – 6 Main functions in a water system
Design requirements
Diff in arterial, secondary, small