Research on novel highway filter drain designs for the protection of downstream environments Stephen J. Coupe, Luis A. Sañudo-Fontaneda, Susanne Charlesworth, Gordon Rowlands Coventry (Warwickshire), UK SUDSnet International Conference 2015 Session 3. Performance Testing

Introduction Highway filter drains are stone-filled roadside drainage trenches of approximately 1 metre depth and 1 metre width and run parallel to significant parts of the UK high speed road network. They are a relatively unknown drainage asset, but with over 7,000 kilometres of filter drain in the UK, they make a significant contribution to the functioning of the national economy as a key piece of the transport infrastructure.

Refurbishment in action

Hypotheses The inclusion of a geotextile within the structure of a filter drain produces an improvement in the discharged water quality and does not lead to a drainage failure. The position of the geotextile within the filter drain structure can modify the attenuation power of a filter drain and the quality of its outflow.

Rigs setup No geotextile (1 rig) No geotextile (3 rigs) Bottom geotextile (3 rigs) Top geotextile (3 rigs) Description of the rigs Volume: m 3 (0.21 m x 0.21 m x 0.65 m). Surface: m 2 (0.21 m x 0.21 m). Methodology 10 rigs

Hydraulic tests 100 mm/h5 minutes10 minutes15 minutes200 mm/h5 minutes10 minutes15 minutes400 mm/h5 minutes10 minutes15 minutes Methodology

Rainmaker  Volume of water: 4.2 L/test (7 tests achieve 700 mm/year). This volume of water was obtained by using the rainfall simulator under the following conditions after the addition of sediments:  Rainfall intensity: 400 mm/hr.  Storm duration: 15 minutes.  Amount of sediments: g/test to simulate 1,000 g/m  year (7 tests achieve one year of addition of sediments).  Amount of oil: g to simulate extreme conditions of 100 times 9.27 g/year·m 2. Simulated conditions  Intensity range: mm/h.  Temperature: 16-20ºC.  Drop size: 3.5 mm of diameter.  Energy: 1.12  10-4 J/droplet.

Methodology Relationship between the lab simulation and the field Direct rainfall Surface runoff I = 400 mm/h. t = 15 minutes. Filter drain Hard shoulder Carriageway Q = L/minute o I = mm/h (2 carriageways). o I = 7.14 mm/h (3 carriageways).  t = 15 minutes.

Validation of hydraulics (before sediments) Rainfall intensity

Validation of hydraulics (before sediments) Storm event duration Geotextile

Sediment contaminants

Oil contaminants Many of the pollutants in both the sediment and oil are BOTH biocidal agents and nutrients. All the hydrocarbons are biodegradable, the speed of degradation depends upon presence of nutrients (NPK and trace nutrients) temperature, time, moisture etc

Sediments in effluent Before sediments After sediments

Oil and Zinc in effluent Methodology for Oil extraction Oil extracted with solvent (S 316) and automated extraction and measurement system. Results for Oil extraction Non geotextile concentration in effluent mg/L (n=12). Bottom geotextile concentration in effluent < mg/L (n=12). Top geotextile concentration effluent < mg/L (n=12). Limit of detection (LOD) mg/L. Metals in effluent analysed by Inductively Coupled Plasma (ICP) Total mass of Zinc per treatment No geotextile2.666 g Bottom geotextile1.790 g Top geotextile2.583 g

New cell growth (microbial population increases) OIL Cell Biomass Solubilising and Emulsifying agents Oxygen Oxygenase enzymes Biosynthesis Degradation Pathways (Enzymes) Energy From Carbon Carbon Dioxide Nutrients in polluted Sediment Nitrates Phosphates Iron Sulphates Respiration Biodegradation processes

Evolution of CO 2 from biodegradation Highest evolved CO 2 recorded at the top sampling ports, 5000 ppm in rig atmosphere. This correlates with the accumulation of sediment and oil, showing biodegradation is taking place. Ambient air CO 2 concentration in the lab is typically 400 ppm. Sediment washed down

Bacterial densities

Protist counts Image from

Protist species recorded Rig type Maximum taxa recorded Maximum protist size (μm) Key species Control14Bodo saltans No geotextile11300Actinophrys Bottom geotextile 11500Caenorhabditis Top geotextile12250Vorticella ora/Vorticella/convallaria/convallaria_2.html

Hydraulics after addition of sediments Hydrographs and attenuation levels

Conclusions The inclusion of a geotextile within the structure of a filter drain does not produce a failure in FDs hydraulic performance. The position of the geotextile within the filter drain structure affects the attenuation of a filter drain for water quality and quantity. Biological activity and microbial numbers indicate a vigorous response to contamination and show that the retain contaminants are being degraded.

Discussion and short list for the optimum geotextile for filter drains. Laboratory performance test of geotextiles? On-site investigation of filter drains and analysis of life sized models to improve water quality at priority outfalls. Future prospects and work

Future work- lab study

QiQi Chamber for the collection of water quality samples and sediments General collection pipe (runs under the entire sections of FD’s) Collection pipe for each FD section Gradient direction 10 m Pipe Control chambers Collection pipe Experimental setup Field study

Research on novel highway filter drain designs for the protection of downstream environments Stephen J. Coupe, Luis A. Sañudo-Fontaneda, Susanne Charlesworth, Gordon Rowlands Coventry (Warwickshire), UK SUDSnet International Conference 2015 Session 3. Performance Testing