intro_distr_class_4 - Water Solutions, Inc.

siennatearfulUrban and Civil

Nov 25, 2013 (3 years and 10 months ago)

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Introduction to
Water Distribution

Water Solutions

January 2007

Class #4


46 Slides


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Distributions System Operation


Pipe materials, size, C factor, Capacities


Tuberculation


causes & effects


Valves


types, uses, operation


Pipe handling & trenching


Pipe joining and fitting


Tamping and Backfilling


Pressure and leak testing


Flushing and disinfection


Static & dynamic head, grade line



Corrosion

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Piping Materials

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Piping Materials


There are 4 types of piping systems used:

1.
Transmission Lines

2.
In
-
Plant Piping

3.
Distribution Mains

4.
Service Lines

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Piping Materials


Early pipe consisted of:


Cast
-
iron


Wrought steel


Riveted steel


Wood stave


Pipe today falls into the following
categories:


Gray cast
-
iron pipe


Ductile
-
iron pipe


Steel pipe


Asbestos
-
cement pipe


Polyvinyl chloride pipe


Other (plastic and fiberglass)


PCP or Pre
-
stressed concrete pressure pipe


Pretension concrete pressure pipe


Reinforced concrete pressure pipe


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Piping Materials


Concrete Pipe


Pre
-
stressed Concrete Cylinder Pipe
(PCCP) (Embedded
-
cylinder pipe)


Welded steel pipe


Concrete core placed inside


Concrete coating applied to exterior


Steel wire is helically wrapped around exterior
of steel cylinder


Concrete coating and mortar slurry is added
to the exterior


Typically large diameter pipe


Can withstand up to 400psi and 100’ of cover

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Piping Materials


Concrete Pipe


Pre
-
tensioned Concrete Cylinder Pipe


Welded steel pipe


Concrete core placed inside


Concrete coating applied to exterior


Smooth Hot Rolled Steel
Rod

is helically
wrapped around exterior of steel cylinder


Concrete coating and mortar slurry is added
to the exterior


Typically large diameter pipe


Can withstand up to 400psi and 100’ of cover

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Piping Materials


Cement Pipe


Cement Pipe has Advantages


Inexpensive at larger sizes


High internal and external load capabilities


Resistant to internal and external corrosion


Long Life


Minimal bedding requirements (backfill after install)


Disadvantages include


Heavy


Layout must be precise because of weight and sizes of
piping. (expensive to just add a foot here or there)

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Polyethylene


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C900 pipe

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Ductile Iron

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Steel Pipe


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Valves

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Valves


Valves are used to:


Start and stop flow


Regulate pressure and flow


Prevent Backflow


Relieve pressure


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Valves


Classification of Valves


Gate Valves


Globe Valves


Needle Valves


Pressure
-
Relief Valves


Air
-
and
-
Vacuum Relief Valves


Diaphragm Valves


Pinch Valves


Rotary Valves


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System Appurtenances


Valve classification

1.
Diaphragm (pinch, sleeve).

2.
Rotary (ball, plug, butterfly).

3.
Slide (gate, sluice).

4.
Globe (check, altitude, common household
faucet).


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Gate Valve

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Gate Valve / Slide

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Gate Valve


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Valves


Globe Valve


Household Plumbing


Needle Valve


Small sizes / precise throttling of flow


Pressure
-
Relief Valves


Disk is kept against seat by spring. Pressure exceeding
spring setting will open valve


Air
-
and
-
Vacuum Relief Valves


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Needle Valve

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Control (Globe) Valve

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Ball Valve

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Plug Valve

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Butterfly Valve

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Check Valve

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Main Installation

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Main Installation


Pipe Shipment


Inspection


Unloading


Stacking


Stringing


Inspection


Inspection of pipe for damage in transit & to ensure completed list


Unloading


Care when unloading


unload pipe by type


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Main Installation


Pipe Shipment



Stacking


Pipe should be stacked on flat surface and off of the
ground


Do not allow bells of pipe to touch ground


Place blocks at each end and between layers of heavier
pipe


Pipe with belled ends should be stacked with bells
overhanging barrels and be alternated (to protect bells)


Pipe should be stacked by size and class (type)


PVC pipe should not be stacked over 3 bundles high. If
loose not over 3’ high (Protect PVC from UV damage!)

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Main Installation


Stringing:



Place pipe as close as possible to trench to avoid
excess handling


Excavated trench should have pipe strung on opposite
side of spoil bank


Protect from traffic


Bells in the direction of installation progress


Secure pipe to prevent from rolling


Only enough pipe to complete day


Keep ends clear and prevent dirt from entering


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Main Installation


Trenching


Depth of trench is determined by:


Ground Frost


Ground Water


Traffic Load


Soil type


Size of pipe


Cost


Surface Restoration


Depth of crossing utilities

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Main Installation



Trenching


Minimum required cover for service mains is
typically 2.5 ft of cover (fill over top of pipe)


Minimum required cover for service lines is
typically 18” of cover

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Main Installation


Trench Width


Minimum width for assembly


Safety


Economics


Minimize external loading



Trench width should not be more than 1
-
2ft greater than the OD
of the pipe


48” pipe should have a trench approximately 60”
-
72” in width

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Main Installation


Trenching


When trenching, soils should be placed on traffic side of
trench & far enough from trench so that it will not fall into
trench.


2’ back for trenches less than four feet deep.


4’ back for deeper trenches.


Open trenches should be properly protected to minimize
hazards to the public


Flags, barricades etc.


Only trench enough to complete the days work


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Main Installation


Trenching


Preventing Trench Cave
-
in


All trenches 5ft in depth or greater must be effectively shored to
protect operators.


Less than 4ft in depth should be considered on case by case basis


Sloping


Excavation of walls of trench at an angle. “Angle of Repose” will
vary with soil type, moisture & external conditions


A 2:1 ratio or angle of repose means that there is 2’ of with for
every 1’ of depth to the trench



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Main Installation


Trenching


Preventing Trench Cave
-
in


Shielding
(protects workers from cave
-
in, does not stop cave in)


Box with solid sides but open on top, bottom, and ends.


Important that box extends above top of trench


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Main Installation


Trenching


Preventing Trench Cave
-
in


Shoring
(Prevents Cave
-
in)


Framework of material that applies pressure to trench walls


Uprights


Stringers


Trench Braces


Shoring should be installed from the top down and removed
from the bottom up for safety


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Main Installation


Trenching


Preventing Trench Cave
-
in


Sheeting
(Prevents Cave
-
in)


Framework of material that applies pressure to trench walls


Solid planks provides solid barrier to trench wall


Used in very poor soil conditions (sand) where excavation is
susceptible to vibration etc.


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Main Installation


Common Sense


Potable water mains/pipes should never be laid
in same trench as sewer.


If they must cross the water main should be at least
12”
above

the sewer line.


If water and sewer lines run parallel to each other the
distance between the two should be at least 10 ft


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Main Installation


Bedding of Pipe


Trench should have level bottom!


If soil conditions require special bedding, material
should consist of well graded granular material up to
1” in size. No more than 12 percent clay or silt that
can be sensitive to water (freezing).


Should be spread across entire width of trench


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Main Installation


Laying Pipe


Inspection


Check for damage


Cleaning


Inspect for dirt, oil, objects


Placement


Never rolled into trench.



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Main Installation


Laying Pipe


Installation under RR tracks, highways or other
obstructions


Water must be carried to one side of roadway


Must be capable of repair without damage or service
interruption of RR or highway


Must be protected from dead and impact loads


Most common method is to install casing pipe
(Protective Pipe)


Typically steel or concrete


Casing should be 2
-
8” larger than the OD of the water
main Bell


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Main Installation


Thrust Restraint


Water in Motion!


Fittings that stop or change direction of flow
should be considered candidates for thrust
blocking


Thrust acts perpendicular to the inside surface
it pushes against




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Main Installation


Thrust Restraint


Thrust Control


Thrust Blocks


Cast mass of concrete (must be cast against
undisturbed soil & spread thrust across entire fitting)


Thrust Anchors


Mass of concrete that utilizes steel rods or cables to
connect pipe to concrete


Tie Rods


Typical of mechanical joints


Restraining Fittings


Clamps and anchor screws




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Main Installation


Thrust Restraint


Thrust Control


Thrust Blocks


Cast mass of concrete (must be cast against
undisturbed soil & spread thrust across entire fitting)


Thrust Anchors


Mass of concrete that utilizes steel rods or cables to
connect pipe to concrete


Tie Rods


Typical of mechanical joints


Restraining Fittings


Clamps and anchor screws




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Distribution System Operation


Static Head


Corrosion


more next class


Flushing and Cleaning

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Backfilling & Main Testing


Tamping


Saturating


Water Jetting


Pressure and leak tests


more next class


Flushing


Disinfecting

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Distributions System Operation


Pipe materials, size, C factor, Capacities


Tuberculation


causes & effects


Valves


types, uses, operation


Pipe handling & trenching


Pipe joining and fitting


Tamping and Backfilling


Pressure and leak testing


Flushing and disinfection


Static & dynamic head, grade line



Corrosion

www.h2osolutions.com

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