METHODS FOR MANHOLE RENEWAL

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METHODS FOR MANHOLE RENEWAL

• Michael Shepherd
• D S Contractors

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FREQUENTLY ASKED QUESTIONS

• Why should manholes be renewed?
• Where do manhole defects occur?
• What causes the defects?
• Which factors should be considered for selecting
  the best manhole solution?

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Why should Manholes be renewed?

• Control II
• Reduces treatment and transportation costs
• Extends the useful life of the system

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Why should manholes be renewed?

• Preventative maintenance

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Why should manholes be renewed?

• Keep small problems from becoming big ones!

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Why should manholes be renewed?

• To seal sewerage IN and seal groundwater OUT

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Where do manhole defects occur?

• Frame and Cover

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Where do manhole defects occur?

• The joint between the frame and chimney

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Where do manhole defects occur?

• The corbel and grade adjustment rings

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Where do manhole defects occur?

• Wall cone

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Where do manhole defects occur?

• Bench

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Where do manhole defects occur?

• Channel pipe penetrations

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What causes these problems?

• Erosion
• Ground water infiltration

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What causes these problems?

• Corrosion
• MIC microbiologically induced
• chemical

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What causes these problems?

• Dynamic traffic loads

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What causes these problems?

• Age - Beyond its useful life

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Engineer the solution to fit the problem.

• Do all that is necessary to overcome the defect.
• Select the best long term solution not just a
  temporary fix!
• Invest in proven and cost-effective solutions.

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Manhole Decision Matrix
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ENGINEERED SYSTEM

• Structural Reinforcement
• Water Tight Sealing
• Corrosion Protection

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Structural Reinforcement Hydrostatic Pressure
Resistance
Hydrostatic Pressure Acting on
PERMACAST Structural Shell Buckling of Shell
Pc 24 EI / D3 I t3 / 12
Pc Buckling collapse resistance E
Elastic modulus D Renewed manhole
diameter t Thickness of concrete
liner Manhole Pc of 1/2 shell
Pc of 1 shell 36 dia. 6.7 psi
53.6 psi 42 dia. 4.2
psi 33.4 psi 48 dia.
2.8 psi 22.2 psi Water
depth Hydrostatic pressure 10
ft 4.3 psi 15 ft 6.5 psi 20 ft 8.7
psi
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Corrosion Protection

• Which products provide the best protection in a
  given situation?
• Calcium Aluminate Cement resists early bacterial
  corrosion.
• ConShield prevents bacterial corrosion that
  produce acid.
• Epoxies provide a barrier against bacterial and
  chemical corrosion.

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ConShield

• ConShield is a concrete admixture for the
  prevention of hydrogen sulfide generated
  corrosion common to concrete pipe, manholes and
  similar structures in municipal sewer
  environments. As an additive, it permeates the
  concrete or repair mortar during the mixing phase
  and molecularly bonds to the cement particles to
  become an integral component of the hardened
  product and to create an environment incompatible
  to harmful bacterial growth.
• ConShield becomes an integrated component of the
  hardened binder. It cannot wash off, delaminate
  or lose its effectiveness from wear. Scraping or
  erosion of the concrete surface only serves to
  expose additional material to the environment
  that would otherwise foster bacterial growth. As
  bacterial growth is neutralized, hydrogen sulfide
  gases released from the raw sewerage cannot be
  metabolized and converted into sulfuric acid in
  concentrations sufficient to damage the
  impregnated concrete and mortar.

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The Rehab Process

• Pressure Wash the interior
• Solids collect on debris blanket over the bench

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The Rehab Process

• Plug leaks
• Patch voids
• Establish internal bypass of flows

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The Rehab Process

• Start pumping mortar
• Commence operation of the SpinCaster

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The Rehab Process

• Centrifugal application of mortar
• Radial impingement densely compacts the mortar

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The Rehab Process

• Continuation of application to achieve finished
  thickness

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The Rehab Process

• Verification of liner thickness

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The Rehab Process

• Finished mortar lining at prescribed thickness

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The Rehab Process

• Spin-on application of CorGard Epoxy over fresh
  Permacast mortar

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The Rehab Process

• Epoxy mortar applied uniformly and safely from
  above
• Hazardous entry unnecessary during application

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The Rehab Process

• Inspect CorGard and spark test for pinholes
  holidays

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The Rehab Process

• Fully lined protected

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Engineered System

• New manhole within a manhole
• Inbedded plastic for corrosion protection
• Liner to pipe seal

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The Cast in Place Process

• The process begins with removing loose material.
• Forms are then assembled with or without the
  plastic lining depending on the type and extent
  of corrosion.

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The Cast in Place Process

• Once the panels are in place a monolithic 4,000
  psi concrete wall is poured inside between the
  forms and the old wall.

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The Cast in Place Process

• After the concrete has hardened, the forms are
  removed and seams are welded and the liner is
  spark tested for pinholes and holidays.

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The Cast in Place Process

• The finished product provides an impermeable
  barrier to chemical and biogenic corrosion.

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Solutions Engineered to Fit the Need and Budget