JJMac | Decommission

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. Soil knowledge leads to correct remedial activity.

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

A service which incorporates all aspects of the Silver and Bronze tests along with: An examination of the soils' chemical, biological and physical aspects. Extensive understanding of how and why the soil performs.

Terra Map Gold test includes:

Active (water) pH
Buffer pH
Soil texture
Organic matter
Organic carbon

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 treatment will increase Organic and Microbial levels in the soil

Untreated Stabilised Soil

PLFA Treated Soil

Terra Map is currently the best soil mapping service with the most detailed soil analysis service available linked with the best digital precision farming system.

No comparable service available elsewhere in the UK market
The TerraMap has been scaled down to suit roadways. 3.5M2 not 12M2 for field work

The Ca:Mag ratio is very different in topsoil and subsoil: top soil more free draining than subsoil

Whole Field Analysis of Ca:Mag

Haul Road Strip Analysis of Ca:Mag

C:Clay highlighting lower Organic Matter/high Clay leading to different water and structure dynamics which can be clearly seen on the scan below

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

Natural State Untreated

Subsoil Stabilised with Cement Binder

Organic Matter

The cement stabilisation has Oxidised the Organic Matter

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

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.

The nutrients, mainly Potassium and Sodium will be replenished through the natural Topsoil leachate into the subsoil.

Good Topsoil management is the key to successful decommissioning of stabilised works. All the nutrients and structure to allow successful crop growth takes place within the topsoil.

Pulverisation using Stabilisation Mixer to re-structure the stabilised layer and Samples for Gold Testing

Seeding Early seeding trials in dishes showed very promising results in the Cement Stabilised soil with early establishment of seed growth Seeding

Seeding was carried out on the pulverised soil to introduce Organic Matter and in turn re-introduce Microbial activity.

Seed mix contained Lacy Phacelia, Water Cress, Small-flowered Milk Vetch and Fingered Willow Herb Seeding