Haul Road Decommissioning through soil regenerative process
All regenerative systems start by measuring and understanding the existing soil conditions.
The measurements taken will cover aspects of the Physical, Chemical and Biological functionality of the soil and interpreting these aspects to find out the limiting factor to soil functionality. These principles are used in the following Decommission strategy.
The more we know about the subsoil before we start the better, therefore we should test the soil and then try and balance it back post treatments.
Understanding the effect of the stabilisation process on soils through the Pulverisation, Binder addition and Compaction is essential for compiling the Decommissioning Strategy DECOMSTRAT.
The Decomstrat will require a full suite of tests to be carried out prior and post soil stabilisation. Allowing for correct reinstatement.
Soil knowledge leads to the correct remedial activity, resulting in a fully functional soil.
Ground Stabilisation Strategy Workstream
Soil testing pre-construction work
TerraMap scanned and Gold soil tested, soil scanner detects 4 isotopes which informs the sampler where to collect soil samples for wet chemical testing.
Scan and test results uploaded onto digital, interactive mapping platform Omnia, generate reports digitally on physical printouts
This will show the state ond functionality of the soil, so there is a target to aim for when soil is reinstated.
Roadways put in
Roadways are put in by normal practice after soil has been baseline assessed
Test the roadway again, once stabilised by hydrated lime and cement
Compare in to the original soil, allowing regenerative reinstatement plans to be made before roadway removal is considered
Regenerative reinstament plan
Will cover physical, chemical and biological aspects of the soil, how to balance these to maximise soil functionality post-reinstatement and bring them as close (or better in some cases) to the original.
Parameters include pH, organic matter, bulk density, microbial populations and diversity. Actions include chemical amendments, growing plans to stabilise soil and additions of native microbial consortiums
A clear, ordered programme of work will be issued, including a timeline, before reinstatement. Will include nutrients, seed rates, plant species and biological inoculants to be applied. This will allow for successful development of plans and microbial communities over time (minimum of weeks post application).
Soil inspections post-reinstatement
Carry out physical inspection of the soil profile and visual soil assessment
This is to ensure the regenerative reinstatement plan is working and the soils natural functionality has been either restored or further enhanced.
Soil Tests: using the TerraMap Gold test
Tests are required to be carried out at each stage of the Decommissioning Process.
Testing of the Natural Untreated Soil
Testing of the Binder Treated Soil
Testing of the Regenerated Soil
TerraMap Gold Analysis
An examination of the chemical, biological and physical aspects of the soil. Extensive understanding of how and why the soil performs. Presented on digital maps and paper reports.
The 42 parameters TerraMap Gold test includes amongst others:
Active (water) pH
Buffer pH
Soil texture
Organic matter
Organic carbon
TerraMap Scanning
TerraMap is the best soil mapping service with the most detailed soil analysis, all results are uploaded onto the best digital precision farming platform. No comparable service is available elsewhere on the UK market.
TerraMap scanning vehicles have a sensor on the back which picks up four isotopes from the soil. This informs the driver where to take soil samples for wet chemical testing using the interactive screen in the vehicle cab.
Terra Map Scan Data at Folkingham
The Ca:Mag ratio is very different in topsoil and subsoil: topsoil more free draining than
subsoil due to a chemical imbalance in Calcium and Magnesium in the subsoil.
Whole Field Analysis of Ca:Mag
Haul Road Strip Analysis of Ca:Mag
Carbon:Clay highlighting lower Organic Matter/high Clay leading to different water and
structure dynamics which can be clearly seen on the scan below.
Soil pH
The Stabilisation has increased the pH because of the Ca in the cement.
Remedial Action required
Natural State pH range 7.2 – 7.4
Treated State pH elevated 7.9 – 8.1
Gold Soil Reports
Natural State Untreated
Subsoil Stabilised with Cement Binder
Decommissioned Soil
Organic Matter and pH
The cement stabilisation has oxidised the organic matter seen by a reduction from 8.3 to 7.2 and an increase in Active Carbon %,
the big rise in pH will increase bacterial content and Co2 release. The 3rd result here shows the soil 5 weeks post treatment
showing that the pH is dropping back to the original pH 7.9 , and the organic matter has also increased showing that we are moving
in the right direction. (5 weeks post treatment is not long for remedial action to work)
This soil test was taken 5 weeks after the remedial action and we can see a good direction in travel.
The pH is dropping the organic matter is rising, the C:N ratio is stabilizing. Sulphur is still high but this will drop as the pH drops.
Other nutrients are good which will encourage good plant growth and rooting throughout the profile.
Testing the soil biology: PLFA analysis
Phospholipid Fatty Acid analysis. PLFAs are an essential structural component of all microbial cellular membranes. PLFA analysis is a technique widely used for estimation of the total biomass and to observe broad changes in the community composition of the living microbiota of soil and aqueous environments.
Soil biological testing gives a representation of living soil microbial biomass and allows us to identify the presence or absence of various functional groups of interest through known PLFA biomarkers.
PLFA test measures microbial activity in the soil, ground stabilisation has a very negative effect on soil biology:
Untreated Stabilised Soil
PLFA Treated Soil
Here we can see the reduction in biological activity following soil treatment.
If no biological remedial work is undertaken, soil functionality will be compromised.
Microbial Activity
The cement stabilisation has caused a major decrease in microbial activity and change in C:N ratios due to the death of the microbes. The Cement Stabilisation has effectively killed all biology in the soil.
Natural State subsoil prior to Stabilisation
Cement Stabilised Subsoil
Treatment Plan - DECOMSTRAT
Effects of Cement Stabilisation on Subsoil:
Raises pH
Reduces Organic Matter
Reduces Microbial Activity
De-structures the Soil
Actions Required:
Reduce pH to Buffer level
Increase Organic Matter in the soil
Introduce Micro Biology
Re-structure the soil
All actions in the DECONSTRAT
are determined by the GOLD Test Analysis
Folkingham Stabilisation Decommission Field Trial
Stabilisation of Haul Road Track with 3% CEMI
Haul Road Compaction to >30% CBR
Pulverisation using Stabilisation Mixer to re-structure the stabilised layer and Samples for Gold Testing
pH re-balancing
Ammonium Sulphate and Liquid Nitrogen were delivered in a managed way to achieve the PH and fertility levels of the subsoil.
Nutrients can leach through the profile, this is why we are addressing this through growing a cover crop.
Good topsoil management is the key to successful decommissioning of stabilised works. All the nutrients and structure will allow successful crop growth to take place within the topsoil.
Cover Crop Seeding
Early seeding trials in dishes showed very promising results in the Cement Stabilised soil with early establishment of seed growth
Regenerative Process
Seeding was carried out on the pulverised soil to introduce organic matter and in turn reintroduce microbial activity
Seed mix contained Linseed, Buckwheat, Phacelia, Radish, Mustard, Hairy Vetch and Clover.
Six week established growth in the pH balanced and pulverised subsoil.
Fully established root systems and increased organic matter in the pulverised subsoil.
Cover crop can capture (stop diffuse pollution) of potential environmentally harmful nutrients such as nitrogen and phosphate.
In summary: The soil is measured to ascertain its physical, chemical and bilogical status, all reinestatement works are designed to return this soil back to its native state
These treatments include: Chemical intervention: pH and humic acids, Physical: Pulverisation, Biological: Plant roots and biological inoculants. Organical: Wild Flower Planting
All targeted via Terra map digital mapping system, Gold Standard Analysis and PLFA Analysis.
Haul Road Decommissioned and topsoil fully reinstated after six weeks.
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This soil test was taken 5 weeks after the remedial action and we can see a good direction in travel.
Six week established growth in the pH balanced and pulverised subsoil.
