Bio Remediation

On sites where there is poor soil quality and other problems such as lack of water exit, ESI utilises Bioremediation techniques to improve soil quality and establish vegetation with minimal watering.

Firstly, soil tests are taken to determine soil quality.

Then a specialised range of machinery is used to carry out soil treatments, including deep ripping and spreading of soil amendments.

Specially selected vegetation is planted followed by the spreading of mulch to protect the seed and prevent evaporation from the soil. This mulch layer also protects the area from erosion by breaking up the raindrops and increasing infiltration by slowing runoff.

Bioremediation is the ideal technique to re-establish vegetation on severely degraded sites such as landfills and extractive industry sites. ESI has the experience and the equipment to carry out this work in a timely and cost effective manner.

Case Study

Details

Following the closure of the landfill, the cells where covered and capped with clay. Local site soil was then spread over the site with a number of contour berms installed to arrest sheet flow.

Soil tests were then taken to determine soil quality and a vegetation study was carried out to determine the mix of seed required.

Deep ripping was carried out to break up the interface between the clay capping and the topsoil. In this situation, the control of depth is vital in order to key the two layers together without disturbing the integrity of the clay capping. Following ripping, the soil amendments were spread. Gypsum was spread at 2 tonne per ha and composted organic fertiliser at 4 tonne per ha. A light cultivation was carried out to mix in the soil amendments, before the area was seeded.

The final treatment was to spread a layer of hardwood mulch over the seeded area. This area was spread at a rate of 200 cubic metres per ha.

Results

The location of this site was such that post seeding maintenance was to be minimal. The Bioremediation process chosen allowed for the seed to lay dormant in the soil until sufficient rainfall bought about germination. Following germination the mulch would assist in holding enough moisture in the seed bed to ensure growth. A cover crop of annual grass was planted to give some cover. The selection of grass variety and the sowing rate was important so that this crop did not compete with the permanent native species.