1. Background Research Summary
Ver1.4
Farm Biobed Systems -
to limit point source pollution from pesticide handling and washdown areas.
Background Research Summary
Developed for the Crop Protection Association and Agricultural Industries Confederation by ADAS. The assistance of the Environment Agency, SEPA & the Farming Unions is also acknowledged. This is part of the voluntary initiative to minimise the environmental impact of pesticides

2. Pesticides in water: sources of contamination
Diffuse
Point Source
Non-crop use
drift
tank filling
roads
drainflow
waste disposal
pavements
surface flow
washings
railways
interflow/base
faulty equipment
other hard
seepage
surfaces
leaching
spillages
amenity areas

3. Pesticide handling areas account for 40-70% of pesticide contamination of water
Swedish research
1000 biobeds in use
a significant reduction in pesticides found in surface water
Systems include a biobed directly under the sprayer, which stands on a grid or wheel support system.
UK studies
suggested inclusion of a ‘drive over or direct’ system and use of containment around a concrete surface of a sprayer filling area directing discharge to a biobed.
3 systems set up in Lincolnshire at commercial scale with full monitoring for 2 seasons.

4. Pesticide Handling? Loading Filling Mixing Moving Washdown Interior
Exterior
Small Quantities
High Concentration
Part of the Application Process
Large Quantities
Lower Concentration
Disposal Operation unless “applied” in the field

5. Pesticide Handling Area: Offset or Drive Over
Offset - the handling area separate from the biobed area
Drive Over - the handling area directly over the biobed area

6. What is a biobed used in the study?
A hole in the ground with an impermeable liner and coupled drain-The liner was necessary for controlling discharge and sampling outflow.
2 systems filled with composted mix 50% by volume straw, 25 % soil, 25% peat free compost (Biomix) and turfed over
1 system filled with friable sandy loam soil, not compacted with grass turf over

7. Biobeds challenged by commercial use plus pesticide contamination artificially TWICE in one season
The artificial treatments simulated maximum contamination losses from 16 tank mixes on one day with worse case practice on each load. This contamination would have needed a water volume equivalent to 60 Olympic size swimming pools to meet 0.1g/L
6 pesticides were used as artificial contaminantsas in previous experimental studies. These were sprayed or ‘spilt’ onto each system in addition to inadvertent chemical addition from commercial use
2 artificial applications June and September 2002, 55 days monitoring afterwards

8. Pesticides used as contaminants Source types, volumes and concentrations applied

9. Typical concentrations (g/L) after artificial application to concrete pad to biobed (Similar results were found on the soil based system)

10. Typical concentrations (g/L) after application to Drive-over Biobed
Note: No surface figures quoted as the grid did not retain any liquids. Types,volumes and concentrations applied as for other 2 systems

11. Max. concentrations measured (g/L)
Key Points - Over the two 3-month monitoring periods:
Input concentrations typically reduced by 10, ,000 fold
>1100 individual pesticide determinations from leachate samples
87% of leachate determinations had concentration <0.5g/L (<LOQ)

12. Operational Aspects Water Storage - Flow Management & Biobed Moisture
Drip Irrigation to Biobed and Disposal Area
Annual Biomix Top-up
Lining to Biobeds
Winterisation
Long Term Biomix Disposal - Residues

13. Water management - Storage, Distribution and Biobed Moisture
Offset systems
Receive rainfall from sprayer area and biobed.
Storage between bunded sprayer area and biobed beneficial - probably minimum 1 m3.
Gives flow control and dilution to biobed.
Pump from tank supplies liquid to biobed through drip irrigation
400 mm spacing in pipe and row width for even distribution.
Float switch and time control ‘manage’ system to apply 2-4mm/ day to biobed
In mm rainfall conditions, biobed moisture appears stable.
Biobed- if lined
Directs all water to secondary storage or direct to field disposal area via drip irrigation as per biobed.
Similar systems and controls manage application.

14. Is a lining to the Biobed needed?
Linings were used in the trials
these allowed study of the liquid flowing.
Site surveys considering soil types, watercourses and drains will suggest the need for a lining.
In theory pesticide Handling areas not being used for sprayer washdown may not require a lining
There is a reduced load
Disposal is not taking place
There will be natural dispersal of liquids to the soil strata.
BUT future regulatory uncertainties = if in doubt use a lining
A lining will be required where washdown is to be practised.
It may be beneficial anyway to control all liquid flow in order to manage the distribution to a disposal area.

15. Winterisation
All parts of any Biobed system must be protected against frost.
Maximise protection by below ground installation
No serious problems were found in the research study.
Above ground pipe runs should be laid to allow drainage as far as possible and can be insulated.
Turf cover may assist protection of drip lines on biobed.
Disposal area may benefit with a straw covering.

16. Biomix production and maintenance
The Biomix
50% by volume straw, 25 % soil, 25% peat free compost
Premixed and composted for 5-6 weeks prior to installation
When installed turfed over to increase biological activity.
Mixing is simple-layering on concrete-mixing with tractor loader and composting.
Natural activity in the mix causes the mix to shrink
Each year a topping up of the same mix is required-approx. 300 mm depth top up is needed.
Other organic materials may be appropriate, not trialled yet in UK.

17. Long term biomix issues
Swedish research suggests 6-8 year life of topped up biomix.
Disposal subsequently has been to land - AFTER ONE YEARS FURTHER COMPOSTING. No pesticides have been determined after that period
UK studies have not run for this time scale.
Disposal if Biomix in UK will be subject to Waste Disposal Legislation. Contact Environment Agency, SEPA, EHS NI for guidance.

18. Useful Scientific References

19. Practical Simple Solutions Protecting the Environment
Reductions of 10,000 to 100,000 fold in pesticide concentration on discharge
Practical Simple Solutions
Protecting the Environment
CAUTION
Seek Regulatory Advice Before Building a Biobed
Contact the Environment Agency's Agricultural Waste Line