A27 – East of Lewes Improvements

The A27 - East of Lewes improvements worked involved the collection of 3500 plus geotechnical and geo-environmental samples from over 150 different locations

Client: Highways England | Geoffrey Osborne Ltd | WSP (Engineer)

Site Investigation Value: £400,000

Site Investigation Overview:

The A27 east of Lewes improvements worked involved the collection of over 3500 geotechnical and geo-environmental samples from over 150 different locations from greenfield and carriageway locations to facilitate the detailed design of a new 16km long non-motorised vehicle route.

What Soils Limited brought to the table

Soils Limited were sub-contracted to provide Ground Investigation services to provide Highways England with information relating to ground conditions for the proposed Non-Motorised User route and junction improvements for 16km of the A27 between Lewes and Polegate.

Using our extensive in-house experience, Soils Limited was able to run multiple rig types on concurrent day and night shifts to improve on the client’s deadlines within restrictive road space allocation. This involved collaboration with WSP, the client’s engineer, to adapt and improve the proposed schedule of works.

Our in-house surveying team were utilised to provide PAS128 service clearance ahead of drilling and to provide “as built co-ordinates” upon completion. These co-ordinates where then incorporated into accurate as built CAD plans and AGS4 data.

Over 150 trial holes were drilled using a combination of windowless sampler boreholes with specialist UT70 sampling, dynamic sampling with rotary follow on and machine excavated trial pits. Extensive in-situ testing was undertaken and comprised:

  • BRE365 soakage testing
  • Hand shear vane
  • PID VOC testing
  • DCP-TRRL probing to 2.50m bgl, rising head tests, falling head tests, standard penetration testing
  • CTPu probing.

During site works over 3500 subsamples were taken, stored and sent for geoenvironmental and geotechnical laboratory testing. All trial holes were logged to BS5930 by Soils Limited experienced logging engineers. Specialist geotechnical testing included initial consumption of lime, consolidated peak / residual shear box and effective stress testing.

Following the completion of in-situ and laboratory testing all of the collected data was compiled into a single BIMS compatible AGS4 data format to allow the client’s engineer to fully interrogate the information and to construct detailed cross-sections along the proposed route.

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