the environmental implications of road culvert repair ......pipe repair •in the u.s., $23 trillion...

The Environmental

Implications of Road

Culvert Repair

Technologies

Bridget Donaldson

Senior Research Scientist

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Presentation Overview

• Culvert repair technologies

• Past and ongoing research by VCTIR

– Cured-in-Place Pipe repair study and resulting

specifications

– Other lining technologies being

evaluated

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Pipe Repair

• In the U.S., $23 trillion in water and sewer

infrastructure needs to be spent in next

20 yrs

• Pipe/culvert repair

technology has grown rapidly

• Repair technologies originated

for underground pipes

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Culvert Repair

Deterioration of culverts is an increasing

problem for transportation agencies

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Open cut

Trenchless

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Trenchless Technologies

Six Main Categories:

• Slipliners

• Spiral wound liners

• Fold and form liners

• Spray-on liners

• Cured-in-place pipe liner

• Pneumatically applied concrete (Shotcrete)

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Slipliners

PVC or steel inserted into host pipe, annular space

is grouted

- Benefits: no chemicals or resins

- Disadvantages: reduction in flow capacity

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Spiral Wound Liners

Sections of PVC wound and

welded around spiraling

machine, annular space

grouted

- reduction in flow capacity

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Fold and Form Liners

Folded liner, unfolds and expands to

fit shape of damaged pipe

- minimal reduction in flow capacity

- 18”-21” max diameter

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Spray-on Liner Epoxy spray, solidifies immediately

- Disadvantages: pipe must be completely dry,

environmental issues?

- Advantages: cures quickly, no reduction in flow capacity

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Cured-in-place (CIPP) Liners Flexible liner coated with resin, expands to fit shape of

damaged pipe,

- minimal reduction in flow capacity

- environmental issues

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Pneumatically Applied Concrete Concrete application along culvert bottom

- Raises bottom elevation (at least 4 in)

Costs

Longevity

Highest $

Varies greatly depending on pipe and site

conditions

Lowest $

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VCTIR study: Are there any environmental

implications of these pipe repair methods?

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Trenchless Technologies

Six Main Categories:

• Slipliners

• Spiral wound liners

• Concrete (Shotcrete)

• Spray-on liners

• Cured-in-place pipe liner

• Fold and form liners

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Trenchless Technologies

Six Main Categories:

Slipliners

Spiral wound liners

Concrete (Shotcrete)

• Fold and form liners

• Spray-on liners

• Cured-in-place pipe liner

Steel, PVC, HDPE + grout

Entail a chemical

transformation

Increased enforcement of

permitting regulations

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Trenchless Technologies

Six Main Categories:

Slipliners

Spiral wound liners

Concrete (Shotcrete)

• Fold and form liners

• Spray-on liners

• Cured-in-place pipe liner

Steel, PVC, HDPE + grout

Entail a chemical

transformation

Increased enforcement of

permitting regulations

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Trenchless Technologies

• Fold and form liners

• Spray-on liners

• Cured-in-place pipe liner

Will be evaluated this year

Lab study (2009) found no env

effects, would like to evaluate in field

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Cured-in-place Pipe Repair

• CIPP operations span the U.S. and 40

other countries

• Most common repair method for

underground pipes

• Repair method used by nearly all U.S.

DOTs, and for approx 1/2 of VDOT’s

culvert repair projects before 2007

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CIPP (conventional)

• A resin-saturated felt liner is pulled or inverted through host

pipe

• Water or steam inflates the liner, conforms to shape of host

pipe

• Heated water or steam re-circulates and cures the resin

• Cool-down period, then ends of cured liner are cut open

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CIPP (conventional) Resin is 30-50% styrene

• Styrene is an EPA priority pollutant, potentially carcinogenic

- Max Contaminant Level (MCL) for drinking water: 0.1 mg/L

• Styrene from uncured resin from CIPP installations has

caused fish kills (FL, Canada) and damaged water treatment

plants

- Toxicity level for rainbow trout: 2.2 mg/L

• Vapor from styrene in CIPP installations has entered buildings

and homes and exceeded allowable exposure levels

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CIPP study (VCTIR)

• Monitored 7 CIPP installations in VA

• Collected water samples before, during,

and after installations

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CIPP

Observations:

• Discharge of hot cure water

• Uncured extruded resin

• Algal blooms

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CIPP

Water Sampling Test Results

• Styrene concentrations were as high as 77 mg/l and were detected up to 88 days post installation

- 770 times the MCL for drinking water

- 31 times toxicity values for rainbow trout and water flea

• Styrene concentrations exceeded the toxicity values of the rainbow trout and water flea at four of the seven monitored project sites (for up to 24 days post installation)

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CIPP Styrene concentrations detected in water samples

resulted from one or a combination of the following:

• Installation practices that did not capture condensate

containing styrene

• Uncured resin that escaped from the liner during

installation

• Insufficient curing of the resin

• Some degree of permeability in the felt lining material

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CIPP: VDOT Response

• VDOT immediately placed a stop work order on all

styrene-based CIPP repair projects contracted by VDOT

(2007)

• A VDOT task group led by VDOT’s Environmental

Division was formed to evaluate further the use of

steam- and water-CIPP repair projects containing

styrene

• VDOT developed new specifications for CIPP repair

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VDOT’s CIPP Specifications

• VDOT project inspector must provide oversight

• Thermocouples required during installation

• Additional lining materials are required to ensure capture of extruded uncured resin

• Finished liner must be rinsed before reinstating water flow

• Cure water and rinse water must be captured and disposed

• Contractors must hire independent labs to test water before and after each project

California has reduced its use of CIPP

New York State DOT has also issued new CIPP specifications

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Other CIPP Methods being

Evaluated Epoxy (styrene-free) CIPP

- small amount of uncured, extruded

resin observed

- some samples exceeded aquatic

species toxicity thresholds

- water volume and

dilution have important

effect on chemical

concentrations

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UV-CIPP

(styrene)

- Uses 1/3 of the resin as compared to conventional method

- Fiberglass liner, inner and outer impermeable foil

- Produces no effluent

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UV-CIPP

Preliminary test results: Many samples were non-detect, but some exceeded aquatic species toxicity thresholds

Recommended Considerations for

New Lining Products

• Field-test and monitor new products before

approval

• Detailed specifications for projects requiring

resin or spray

- rinse liner, capture and dispose of effluent

and rinse water, test water samples after

installation

• Installation oversight with trained inspectors

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Final VCTIR report will be available 2012

Will include information to assist with pipe

repair product selection and specification

development