Operation and Maintenance of Sewer Laterals

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Operation and Maintenance of Sewer Laterals
City of Saskatoon

• City of Saskatoon
• Public Works Branch

SPWA 2002
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Comparison of Service Cleaning Frequency
Number of Blocked Service Connections / 1000
Service Connections
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PRESENTATION OUTLINE

• Where do we get our mandate?
• Determining program demand for cleaning and
  rehabilitation programs
• Cleaning and rehabilitation strategies
• Questions

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(No Transcript)
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Infrastructure Maintenance Goal

• Maintain the infrastructure at a defined level
  of service at the minimum long term cost.

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Rules for the Road

• Urban Municipality Act (Section 188)
• Public Health Act
• Saskatchewan Plumbing and Drainage Regulations
• Canadian Plumbing Code
• Nuisance and Negligence Jurisprudence
• Local Bylaws and Policy

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Urban Municipalities Act

• The U.M. is responsible to maintain the sewer
  service from the main to the property line
  (188.2)
• The U.M. may direct the owner to undertake
  repairs from the property line to the building
  (188.3)
• The U.M. on expiration of the life may repair,
  maintain replace or reconstruct the sewer service
  at the expense of the municipality or owner
  (188.5)

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Public Health Act Plumbing Code and Regulations

• The U.M. may regulate the plumbing within the
  building and from the building to the property
  line
• The U.M. may direct the owner to make repairs,
  alterations or replace the plumbing

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Set Requirements Around Plumbing Layout

• Cleanout
• Cap Size
• Cleanout Location and Work Space
• Cleanout and Plumbing Alignment Layout
• Pipe Size

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Nuisance

• The U.M is responsible if a blockage originates
  on City Property or is due to an action by the
  City
• The owner is responsible if a blockage originates
  on private property or is due to an action by the
  property owner

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Legislated Policy Options

• Age of the Connection
• Physical Location of the Pipe
• Cause and Location of Obstructions
• Plumbing Access

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Other Policy Consideration

• Coordination with Mainline Rehabilitation
• Coordination with Water Service Replacement
• Replacement During Lot Redevelopment
• Emergency versus Planned

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Two General Approaches to Connection Programming

• The Municipality Provides Cleaning and
  Maintenance Programs
• The Owner is Responsible for Securing a Plumbing
  or Sewer Contractor

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Policy Should Consider

• Level of Service
• Response time
• Interruption Frequency
• Obstruction Location
• Property Side
• City Side
• Who Initiates /Undertakes the Work
• Property Owner
• Municipality
• Reimbursement and Service Fee Policy

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Policy Should Consider

• Cause of the Blockage
• Internal Plumbing
• Private Trees
• City Trees
• Both Private and City Trees
• Pipe Condition (alignment and structural defects)
• Foreign objects (sand soil, sanitary supplies,
  grease and other materials).
• Unknown (no City or private trees and no
  structural condition exists)

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Simple No!
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Factors Impacting Demand for Cleaning and
Rehabilitation Programs

• Pipe Condition
• Inventory
• Pipe Material, Jointing and Age
• CCTV Inspection
• Tree and Shrub Type
• Root System
• Tree Location/Proximity to Pipe
• Seasonal Growth Cycle

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Know Your Inventory Before You Set Policy

Inventory by Construction Period and Material Type
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Connection Inventory (City of Saskatoon)
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Sanitary Connection Pipe Material Type
25141
20616
8604
Total 55,870 connections
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Cleaning Services by Pipe Type
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Sewer Blockages by Cause
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External Site Assessment

• Location of Sewermain
• Location of Private Trees (site, adjacent,
  across)
• Distance (on top, 0-3m, 3-6m, over 6m)
• Tree type (Cedars, deciduous, Evergreen, hedge)

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Breakdown Of Tree Root Servicing
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Sewer Blockages Based On Nuisance
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Variance in Cleaning Service Demand

• Demand for cleaning service is highly variable
• Daily
• Weekly
• Monthly
• The time period between taping and Augering
  connections is highly variable.

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Seasonal Demand for Cleaning Services
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Cleaning Service Demand by Week
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Typical Failure on Tile Pipe

• Root mass at a joint

• Tap roots at a joint

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Structural Defects Tile Pipe

• Broken Pipe at
• the Elbow

Broken Pipe
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Structural Failures on Fibre Pipe

• Deformation
• Found in Fibre pipe connections

Fibre pipe in good shape
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Structural Failures Fibre Pipe

• Fibre Pipe in fair condition

Fibre Pipe in poor condition
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Alignment/Profile Problems

• Sagging or heaving connections
• Wide range of severity

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Alignment/Profile Problems

• Large Open Joint

Large Displaced Joint
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Cleaning Operations

• Cleaning Average Expected
• Method Cost Life
• Sewer Tape 50 7.5 Months
• Sewer Auger 100 15 Months
• High Pressure Flusher 62 15 Months
• (Harben)
  
• Herbiciding 170 24-48 Months

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Connection Preservation

• Treatment Average Expected
• Method Cost Life
• Spot Repairs 2000 Various
• Lining (Full) 3300 gt 50 years
• Less Trench Replacement 3200 gt 75 years
• Open Cut Replacement 4800 gt 75 years
• Note Replacement costs based on City portion
  only

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The Replacement Versus the Cleaning Decision

• Based on economics replace when
• Three of more auger treatments a year
• Six or more sewer tapings a year
• Requires spot repair at the elbow
• Will economics change?

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SEWER TAPE

• Where
• Soft Blockages
• Root infiltration
• Used to get connection running
• Average Cost 50/con.
• Production
• Two Man Operation
• 12con. /day

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SEWER AUGER

• Where
• Soft Blockages
• Root infiltration
• Grease
• Long runs, bends, elbows
• Up to 125mm Diam.
• Average Cost 100/Con.
• Production
• Two Person Operation
• 5 con./day

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HIGH PRESURE SEWER FLUSHER

• Where
• Grease, root infiltration
• Long runs, bends,elbows
• Manhole access
• Can use on gt 125mm
• Limited use with fibre pipe
• Average Cost 62/Con.
• Production
• One or two person operation
• 15 to 20 con /day

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Connection Herbiciding

• Where
• Extensive Root Infiltration
• Cost 170/connection
• Production Up to 10 connections per day
• Effective 2-5 years??
• City of Saskatoon ran a test program in
  2001-2002, 100 connections

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Vaporooter Herbiciding

• Roots augered 4-6 weeks prior to treatment.
• 5 gallon mix water, Vaporooter (1quart).
• Mini-foamer pumps until solution container is
  empty (10-15min).

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Vaporooter Herbiciding

• Homeowner to refrain from using water for at
  least 2 hours after treatment.
• All foam washed out with commencing normal use of
  water.
• Restricted use- certification, training and
  licensing required of application personnel.

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Open Cut Replacement

• Where
• Extensive structural problems
• Alignment Sags and Heaves
• Where water services must also be upgraded
• Typical Cost 4,800 per connection
• Restoration
• Involves major restoration to road, boulevard,
  sidewalk, property

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Less Trench Replacement

• Where Extensive structural problems
• Cost 3,750 per connection
• Restoration
• minimized to one hole at the main and one hole at
  the house
• additional hole at the property line if water
  line is replaced at same time.

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Sewer Connection Lining

• A thermal resin impregnated flexible felt woven
  liner is inserted into the connection
• Inversion Process
• Winch in Process
• Liner is cured by circulating hot water, steam or
  ambient air at a regulated pressure.

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Sewer Connection Lining

• Where
• Minimal structural problems
• Extensive root infiltration
• Restoration charges would be expensive
• Cost 3300 /connection (130/l.m.)
• Production 4-5 connections/day
• Restoration
• Very little disruption to users and existing
  infrastructure

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Connection Lining (Winch-in Method)

• No digging.
• Able to line up to and including 90º long sweep
  bends.
• Spot repairs possible.
• 50-year design life.

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Pull in Connection Lining

• Wet out procedure- Pre-cut Liner is
  impregnated with resin.
• Inflatable air bladder exists within the liner.

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Pull In Connection Lining

• Liner is winched into thoroughly cleaned
  connection through cleanout, from nearby manhole.
• Air bladder is inflated and air pressure is
  regulated by an air compressor until liner is
  cured.

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Connection Lining

• Bladder is then deflated and removed from the
  connection.
• Connection is inspected with a small CCTV camera,
  pushed in through the cleanout.

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Completed Sewer Connection Lining
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Summary

• Sewer Lateral policy is not for faint of heart
• In this day and age of litigation it is probable
  a necessity

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Questions ?
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Types of Herbicide

• Copper Sulfate
• Only kill roots in the bottom of the pipe
  (transported in flowing water), and not
  acceptable at treatment plant.
• Corrosive Acids and Bases
• Only kill roots in the bottom of the pipe (react
  with water to create heat and burn the roots),
  and do not inhibit root growth.
• Diquat Bromide
• Not approved in Canada.
• Dichlobenil
• Kills the roots, but does not inhibit root
  growth.

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Metam Sodium / Dichlobenil Mix

• Kills all roots.
• Metam is a fumigant that gives the immediate root
  kill.
• The mix is transported by a foaming agent, such
  that roots in the entire pipe are contacted.
• Inhibits root growth.
• Dichlobenil is a herbicide that impregnates the
  surface of the pipe and creates a chemical
  barrier to root growth.
• Diluted quantities acceptable at treatment plant.
• Degradation process with metam and adsorption
  process with dichlobenil work to minimize adverse
  effects at WWTP.
• Non-systemic.
• Will not harm the tree(s) causing the root
  problem.