Developing an *engineering approach* to

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Transcript Developing an *engineering approach* to

Developing an “engineering approach” to design and selection of lining systems for irrigation canals.

Part 1 - Analysing results of long term trials to understand failure modes of canal lining systems.

2012 IAL Conference Adelaide

By Nick Kastoumis BEng Civil Geosynthetics Consultant

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

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Why do we need this presentation ?

• • • • The size of water conservation expenditure is huge A lot of systems on the market – how do we assess them?

Long service life requirements + 25yrs Conserving water is vital - getting it wrong - is very costly

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

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The objectives of this presentation – 5 goals

1. Educate decision makers on the body of knowledge available 2. Identify forces in canals and liner failure mechanisms - through analysis of these trials 3. Prompt designers and decision makers to consider these forces when selecting a lining system 4. Call out to other organisations to share experiences with canal lining 5. Find funding for research into quantifying the forces and developing an engineering approach to canal lining design

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

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The 2 main reports that were looked at

1. 1991 – Deschutes Canal Lining Demonstration Project; USBR 2. 1999 – Evaluation of canal lining projects Rio Grande; TWRI • Also considered 2004 – Open Channel Seepage and Control – Guidelines by ANCID o Done in Australia o 3 year period of trials o Installation procedures were assessed o Long term durability was not assessed – would like to follow up with these irrigators to get updates on performance !!

• 1984 - Performance of plastic canal liners – PVC and HDPE

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals 4.

1991 - Deschutes canal lining Demonstration Project

• Funded by USBR – United States Bureau of Reclamation • 34 different lining systems were trialled , installed from 1991 o exposed membranes (16) o Armour/covered systems (11) o Spray ons (7) • Lining systems were evaluated/followed up • During installation • 7yrs on in the 1999 7yr Report • 10yrs on in the 2002 10yr Report • 2011 I have emailed the irrigations districts for feedback on • performance Some 20yr old coupon samples have been taken and tested in 2011

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals 1991 - Deschutes canal lining Demonstration Project [email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals 5.

1999 – Evaluation of Canal Lining Projects in Rio Grande valley

• Conducted by TWRI – Texas Water Research Institute • Two stage of trials and reports were published • TR353 – 2009 Report o 6 different liners were installed in 1999 o PET, PVC, PP, EIA-R, EPDM, PU o Performance was evaluated after 10yrs • TR412 – 2011 Report o Follow up on previously evaluated liners from 2009 , now 12yrs old o New liners were trialled , TPO-R, EPDM-R, PP-R

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals 1999 – Evaluation of Canal Lining Projects in Rio Grande valley [email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

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Identifying forces on canal liners

1. Point out an anomaly • We are good at designing liquid containment o Dams, ponds, reservoirs , lagoons, even landfills o We usually get some leaks o Complete system failure is rare • When it comes to canal liners we have much more failures even complete removal • But its not some “aggressive liquid” •

Its ONLY WATER!!!!!

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

Question:

Why do we continue to design canal liners as if they are pond liners ?

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

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Forces acting on canal liners vs. pond liners

Forces to resist Liquid containment Liquid transportation

Dams, ponds, reservoirs, lagoons Canals , channels

UV and weathering

Exposed areas must resist UV and weathering Exposed areas must resist UV and weathering

Hydrostatic forces

Can be very deep, >3m so puncture is one of the main failure mechanism of containment liners Generally shallow < 3m so subgrade puncture resistance is not important to consider

Hydrokinetic forces

Generally only considered for the inlet and outlet structures , spillways The main failure mechanism of flexible canal liners

Mechanical damage

Can be avoided by fencing or armouring of the liner and or prompt repairs Can be avoided by fencing or armouring of the liner and or prompt repairs

Abrasion

Generally only considered for the inlet and outlet structures , spillways Must be considered for the life of the lining system, including any armour or coverings

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

The moment when the light bulb went on

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

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All of these Canal lining reports – support tearing and abrasion as the most important failure mechanisms of canal liners

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

How did the exposed liners go ?

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

How did the exposed liners go ?

This is puncture

- Hypalon shows excellent puncture resistance. The puncture has NOT progressed for 4 yrs. pg. 94 Deschutes 7yr report

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

But, unable to resist tearing

Hypalon suffers severe Tear

Damage: 0.9mm Hypalon + geotextile 7yrs old – pg. 96 Deschutes 7yr report

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

This is NOT a PUNCTURE, this is a TEAR

- Severe Tear

Damage: 2mm textured HDPE after 6 ½ yrs. service – pg. 87 Deschutes 7yr report

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

This is NOT a PUNCTURE, this is a TEAR

Severe Tear

Damage: 1.14mm unreinforced EPDM rubber, less than 8yrs service – pg. 16 TWRI Report 2008

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

Life prediction of exposed liners – be careful !!

Table 13.-Coupon Testing of Exposed Geomembrane test sections

. From Deschutes 10yr Report pg 191

Section A~3 A-4 Material Age

80-mil Textured HOPE 10 years 30-mil PVC with Bonded Geotextile 10 years 45-mil Hypalon 10 years

Visual Assessment

Excellent Very Good

Physical Property Testing

Elongation down 90% OIT down 30% Tensile up 30% Modulus up 140% Elongation down 70% Tear strength down 60%

Service Life Prediction

20-25 years 10-15 years

A-5

Fair to Poor 10-15 years

A-6

36-mil Hypalon 10 years Fair Tear strength down 60% 10-15 years

0-3 0-4

45-mil EPDM 30-mil LLDPE 2 years 2 years Excellent Excellent Elongation down 30% Tear strength down 50% Tensile down 10% Tear Strength down 10% 15-20 years 10-15 years

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

Life prediction of exposed liners – be careful !!

Table of lining performance. TWRI Report TR412 pg 13 [email protected] - Geosynthetic Consulting - Third Party Geomembrane CQA

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

Life expectancy vs Tear , is there a correlation ?

Tear strength of some geomembranes used in Deschutes and TWRI canal lining trials

600 500 400 300 200 100 0

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

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How did the spray on liners go?

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

How did the spray on liners go?

• Some points on membranes spray applied to geotextile I have worked with some spray on membranes and even failed at developing my own • The main problem is LACK OF SATURATION • The liquid is made up of 2 parts o Solvent – the carrier o Solids – the final membrane • 2 main plains of failure o Bonding to substrate – does not occur o Solvent penetrates geotextile but solids remain on the top o No solids saturate the geotextile. The result is   Thin bonding interface between film and geotextile Porous surface of 3D geotextile •

Solids must saturate the geotextile to take advantage of its mechanical strength !!

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

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How did the covered liners go?

There were 4 types of cover 1. Unreinforced shotcrete 2. Reinforced shotcrete 3. Grout mattresses 4. Soil – we wont cover this here

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals Unreinforced shotcrete

main failure mechanism of unreinforced shotcrete was cracking – typical of local settlements and inconsistent thickness Photograph 122.— Importance of Tensile strength. Close up of 300mm diameter hole in shotcrete lining. Shotcrete is less than 25mm thick.

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals Reinforced shotcrete

main failure mechanism of fibre reinforced shotcrete was cracking – typical of shrinkage and inconsistent thickness Importance of flexibility. Transverse crack is running all the way across the channel

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals Grout Mattresses

main failure mechanism of grout mattresses is abrasion Photograph 103.— Severity of abrasion in canals. Geotextile is deteriorated by abrasion. Note that some of the grout bricks are also missing in this area.

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

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In summary

Next time you consider a lining system for a canal, past experience shows that to meet long term durability requirements 1. Exposed membranes – need to be assessed for o abrasion and tearing strength o UV and weathering o For the whole service life !!

2. Amor and cover systems have issues too • Shotcrete lacks flexibility so a designer must consider o subsurface drainage o Long term differential settlement • Grout mattresses must consider o long term abrasion 3. Spray on membranes – are yet to be proven as long term effective lining systems

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Developing an “engineering approach” to design and selection of lining systems for irrigation canals

Thank you

Any questions ?

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