a laboratory study to assess the hydraulic and water treatment performance of geotextiles within...
TRANSCRIPT
A laboratory study to assess the hydraulic and water treatment performance of
geotextiles within simulated filter drains
Anne-Marie McLaughlin, Dr. Stephen Coupe, Dr. Luis Sañudo-Fontaneda, Daniel Castro-Fresno and Elena Blanco-Fernandez
Structure
1. Introduction
1.1. Definition and Characteristics
1.2. Aims and applications
1.3. Applications in SuDs
1.4. Research history
1.5. Current research at CU
2. Project aim
3. Methodology
3.1. Materials
3.2. Methods
4. Results
4.1. Hydraulic behaviour
4.2. Sediment attenuation
5. Future Work
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1.1. Definition and Characteristics
• The term ‘geotextile’ was introduced by Jean-Pierre Giroud in 1977.
• Geosynthetic:
“Generic term describing a product, at least one of whose components is made from a synthetic or natural polymer, in the form of a sheet, a strip or a three dimensional structure, used in contact with soil and/or other materials in geotechnical and civil engineering”
ISO 10318-1 (2006) 3
Geosynthetic barrier
GeogridGeotextile
Geocomposite
1.2. Aims and Applications• Geotextiles are an emerging environmental technology that has been successfully researched.
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1.3. Application in SuDs
• Porous structure and permanence is an essential property in SuDs.
• Research on the use of geotextiles in PPS has been extensive and has proven to be advantageous.
• Geotextiles are made of plastic polymer fibres or threads Fig. (Lee and Borudeau 2006)
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1.3. Application in SuDs
Diagram of a highway filter drain
• In a filter drain geotextiles are used as a wrapping layer
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1.3. Application in SuDs
• Micro-organisms (including bacteria, fungi and protists) form a mature self-regulating biofilm.
Fig. (a) SEM biofilm (b) TEM bacteria from effluent (c) Cilliate of genus Colpoda (d) Testate amoeba genus Euglypha (e) Rotifer (Coupe, 2004) 7
1.4. Research history
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1.5. Current research at CU
• Research on novel highway filter drains
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Structure
1. Introduction
1.1. Definition and Characteristics
1.2. Aims and applications
1.3. Applications in SuDs
1.4. Research history
1.5. Current research at CU
2. Project aim
3. Methodology
3.1. Materials
3.2. Methods
4. Results
4.1. Hydraulic behaviour
4.2. Sediment attenuation
5. Future Work
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Project aim
Overall project aim:
To test the hydraulic and water quality performance of new geotextile
designs in simulated filter drains
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Project aim
Preliminary study aim:
To identify two suitable geotextiles from the range of new designs in terms of hydraulic behaviour and
water quality performance.
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Structure
1. Introduction
1.1. Definition and Characteristics
1.2. Aims and applications
1.3. Applications in SuDs
1.4. Research history
1.5. Current research at CU
2. Project aim
3. Methodology
3.1. Materials
3.2. Methods
4. Results
4.1. Hydraulic behaviour
4.2. Sediment attenuation
5. Future Work
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3.1. Materials
Rig number Description
1.1 Oleophobic material
1.2 Oleophobic material (reversed side up)
2.1 Hydrophilic material
2.2 Hydrophilic material (reversed side up)
3 Hydrophobic material
4 Needle punch material
5 Thin needle punched material
Table 1. Description of the candidate materials and the control rigs.
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3.2. Methods
• Laboratory recreation of a storm event to test the ability of the geotextiles to retain sediments
• Separate additions of sediment in 10g, 50g and 100g were made to the surface of the buckets
• Washed through with 2000ml (200ml/min) of tap water and the effluent collected in bottles
• A 500ml subsample was filtered to determine the mass of sediment deposited
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3.2. Methods
The second stage of the testing programme:• Hydraulic performance: Prior to contamination, 4 rainfall intensities of 50, 100, 200 and 400mm/hr at increasing durations of 5, 10 and 15minutes in filter drain structures.•Water quality and clogging: pollutants will be added together with a rainfall intensity of 400mm/hr for 15mins duration.
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3.2. Methods
The second stage of the testing programme for water quality:• Oil retention by Horiba and heavy metal concentrations by ICP-OES. • CO2-O2 balance will be measured to assess the treatment of organic pollution. •Microbiological variables will be determined by plate counts and phase contrast microscopy.
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Structure
1. Introduction
1.1. Definition and Characteristics
1.2. Aims and applications
1.3. Applications in SuDs
1.4. Research history
1.5. Current research at CU
2. Project aim
3. Methodology
3.1. Materials
3.2. Methods
4. Results
4.1. Hydraulic behaviour
4.2. Sediment attenuation
5. Further work
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4.1. Hydraulic behaviour
Fig. Cumulative discharge volume registered for all the candidate materials used in the experiments and the control rig with no geotextile during the 10 minutes storm event simulated in the laboratory.
0 1 2 3 4 5 6 7 8 9 10 11 120
200
400
600
800
1000
1200
1400
1600
1800
2000
Geotextile 1.1Geotextile 1.2Geotextile 2.1Geotextile 2.2Geotextile 3Geotextile 4Geotextile 5CONTROL
Time (minutes)
Cum
ulati
ve D
ischa
rge
(ml)
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Fig. Discharge rates registered for all the candidate materials used in the experiments and the control rig with no geotextile during the 10 minutes storm event simulated in the laboratory.
0 1 2 3 4 5 6 7 8 9 10 11 120
50
100
150
200
250
300
350
Geotextile 1.1Geotextile 1.2Geotextile 2.1Geotextile 2.2Geotextile 3Geotextile 4Geotextile 5CONTROL
Time (minutes)
Disc
harg
e Ra
te (m
l/m
in)
4.1. Hydraulic behaviour
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4.2. Sediment attenuation
• None of the buckets released more than 1g/l of sediment following any single sediment application.• Final cumulative sediment mass discharged was significantly less than 1% of the total sediment applied to the surface.
Fig. Visual water quality of water collected after passing through the buckets.
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10 g silt added 50 g silt added 100 g silt added0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
1.11.22.12.2345con
Mass of silt added
gram
s per
litr
e se
dim
ent d
ischr
ged
Fig. The mass of sediment discharged from buckets containing the geotextiles with 3 masses of added sediment to the surface.
4.2. Sediment attenuation
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Structure
1. Introduction
1.1. Definition and Characteristics
1.2. Aims and applications
1.3. Applications in SuDs
1.4. Research history
1.5. Current research at CU
2. Project aim
3. Methodology
3.1. Materials
3.2. Methods
4. Results
4.1. Hydraulic behaviour
4.2. Sediment attenuation
5. Further work
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5. Further work
• Geotextile 3 (thick hydrophobic) performed the best in terms of sediment removal
• Geotextile 1.2 (hydrophilic reverse side up) presented the best hydraulic performance in terms of the attenuation levels and infiltration rates.
• These two geotextile materials have been chosen for the second stage of this project.
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5. Further work
Geotextile 1 Geotextile 2 Terram Control
Geotextile 1.2 Geotextile 3 A control and industry standard
(Terram)
No geotextile
3 rigs 3 rigs 3 rigs 1 rig
Table 1. Treatment rig numbers and components
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