The job was a burst main repair at Estuary Road Kings Lynn which was carried out with an excavation of approximately 6.2m long x 3.4m wide and 3.5m deep over the Bank Holiday weekend of 1st to 3rd May 2021.
Due to lack of availability of permanent reinstatement resource over that weekend (asphalt plants not open) the decision was taken to ‘make safe’ the excavation by partially backfilling to a safe level of 1.2m deep with sand fill to avoid the necessity, and allow for the safe removal of ‘temporary works’.
Due to a combination of heavy rain and water ingress into the open excavation over the weekend the sand fill had become saturated and flooded beyond the acceptable standard for use as backfill material.
Traditional options would be to remove all the saturated material, dispose at landfill and replace with dry material. Costly, time consuming and not very environmentally friendly.
On that basis we took the opportunity to try the Mud Dry soil stabiliser which to date had not been tested on such a large scale.
When we arrived on site the excavation looked like this:
We pumped to remove the excess water:
Which left a saturated excavation which looked like this. Oh Dear…
An extremely sloppy mess!
Sprinkle on the product:
Give it a stir with the digger bucket and keep mixing for 5 – 10 mins:
As the material dries out dig it onto the side of the excavation:
Now a full heap of dry material ready to be used as dry backfill:
We even managed to use the excavated material that had been left on the side of the excavation, mix it in with the treated material so that the only waste was the asphalt lumps removed when mixing which minimised waste volumes considerably.
Good old-fashioned soil test of the now treated material before re-use.
Backfill the hole with the now dry material.
Now ready for compaction:
Soil samples were taken for testing of the material treated only with mud-dry (bottom image) and a sample of the same material treated with hand mix SMR (top image).
The Samples were taken to allow us to continue to better understand the relationships of the 2 products, for example does the mud-dry effect the ability of the SMR to harden?
Initial trials have seen excellent results and we currently have cube testing samples under 7, 14- and 28-day tests for absorption and compaction.
Further results of ongoing testing to follow.