SOCOTEC Delivers Time and Cost Savings for Newhaven Port Access Road Project

Pre-Construction Services

A number of pre-construction services have been delivered by SOCOTEC in order to identify the existing conditions of the site and areas adjacent to the site, starting with first establishing the risk of any unexploded ordnance (UXO).

Establishing the Risk of Unexploded Ordnance

The area of Newhaven Docks had been exposed to various forms of ordnance during the Second World War and, as such, the risk of unexploded ordnance (UXO) was identified.  The contract required BAM Nuttall to undertake magnetometer surveys across the site prior to any construction works in order to mitigate the risk of UXO.

SOCOTEC worked closely with BAM Nuttall during the preconstruction phase to establish if an alternative solution could be considered. Those conversations resulted in a more detailed UXO risk assessment being carried out and established that the prevailing UXO risk was within acceptable limits, i.e. low/very low, and that magnetometer surveys were no longer required.

As a consequence of the detailed risk assessment, cost and time benefits for the project were realised, whilst still retaining a high level of health and safety. Once the risk from UXO had been established as low, ground investigation works could be carried out to help inform the design of the foundations.

Ground Investigation Works to Inform Foundation Design

Due to the site’s coastal location at the mouth of the River Ouse, the site is underlain by various layers of alluvial deposits that extend to a typical depth of about 35m below ground level, whereupon chalk is encountered. Given these expected ground conditions, a targeted ground investigation (GI) was undertaken at the locations of the southern and northern abutments to prove the exact depth and composition of the alluvium and to inform the design of the deep foundations.

The GI comprised the construction of boreholes by cable percussion and rotary methods to depths of up to 60m, and the subsequent laboratory analysis of the recovered samples. At the location of the proposed northern abutment, Cone Penetration Tests (CPTs) were also undertaken to establish additional engineering properties of the soils at these locations.

In addition to the ground investigation, ‘T-Bar’ penetration tests were undertaken at an interim stage of the embankment construction to establish the insitu shear strength of the alluvial soils. Utilising a cable percussion method of drilling, SOCOTEC pre-bored through the granular embankment fill and installed casing to provide temporary support. The ‘T-Bar’ penetration tests were undertaken at those locations to establish if the soils had achieved the required gain in strength to confirm the design assumptions and verify that the placement of additional fill could resume without risk of instability.

Monitoring Embankment Stability and Network Rail Assets

As well as carrying out GI works to understand ground conditions across the site, SOCOTEC’s specialist geotechnical monitoring team – SOCOTEC Monitoring – installed in-ground and surface geotechnical instrumentation to the north and south of Mill Creek to provide BAM Nuttall with information on the soil settlement profiles and the stability of the embankments during and immediately after their construction. 

Track monitoring sensors have also been installed to monitor Network Rail’s asset during the construction works, especially during pile foundations, to provide assurance that any ground movement is within Network Rail’s safety criteria.  The automated and manual monitoring instrumentation is being used to establish the extent of any settlement, the change in porewater pressures, the horizontal displacement within the embankments and the twist and cant of the adjacent rail tracks.

All of the automated instruments are connected to a wireless network on site, with data being automatically uploaded to SOCOTEC Monitoring’s web-based data visualisation platform, Calyx OMS. Data from the manual instrumentation is recovered by the Contractor and manually uploaded to the same platform. Where applicable, trigger levels are set and, if breached, alerts are immediately sent by text to the Contractor’s management team.

Locating Buried Structures

As well as understanding the composition and stability of the ground prior to works beginning, mapping and identification of the existing buried structures beneath the proposed route of the access road formed a vital part of BAM Nuttall’s management plan and, as such, a range of utility and geophysical surveys were conducted to do exactly this.

As the surveys department within SOCOTEC amalgamates both utility and geophysical services, the Contractor had access to a wide range of bespoke utility detection solutions, where standard PAS-128 methods would otherwise be ineffective.

A utility detection survey was carried out comprising industry standard PAS-128 GPR methods to detect power and foul sewer systems. And, as the site consisted partly of steep gradients, was overgrown and had the potential for deep cables, an electro-magnetic mapping survey was also undertaken to detect deeper services, as this method is better suited to these challenging topographic conditions.

Correlated with service records, the surveys served to determine the position, size and type of utilities located below the site to inform the road design, indicating which, if any of the buried structures, may require diverting.

With ground composition, stability and the location of any existing buried structures understood, attention turned to the possible impact of construction works above ground.

Understanding the Impact of Noise

Several residential and commercial areas are located in close proximity to the development site, so it was important to understand how any noise generated by the construction works will impact these adjacent receptors.

SOCOTEC’s environmental team undertook a baseline noise survey at two noise sensitive receptor locations to monitor the existing background levels prior to commencement of the construction works. The surveys were undertaken in accordance with BS5228-1 (2009) and, based on the results, allow BAM Nuttall to ensure that noise levels are limited to within acceptable levels and compliant with the recommendations set by the World Health Organisation (WHO). You can read more about environmental noise monitoring in this blog.

With pre-construction services in place to test and monitor a range of existing below and above ground conditions, the final service being delivered by SOCOTEC ensures that materials such as concrete and aggregates are compliant with the project’s earthworks specification.   

Ensuring Compliance with Earthworks Specifications

The construction of the Newhaven Port Access Road requires approximately 1000m3 of insitu concrete, 5,000m3 of Class 6 granular material and 60,0000m3 of Class 1 Ballast as Dredged (BaD) material. Over the next 18 months, SOCOTEC is providing a range of insitu and laboratory tests to demonstrate that these materials and their placement comply with the project’s earthworks specification.

All sampling and testing is undertaken by SOCOTEC’s technicians in accordance with UKAS accreditation, which is based upon the current European and British Standards. Nuclear density gauges are utilised to provide insitu results of the moisture and density of the compacted soils so that the degree of compaction can be assessed immediately and compliance confirmed. In addition, an on-site, temperature-controlled, concrete sample curing facility is provided to ensure that sample storage fully complies with the stringent requirements of the UKAS accreditation.

Results from the insitu and laboratory tests are uploaded onto SOCOTEC’s web based digital management system, MiPortal, allowing the Contractor to immediately access all of the test data and trend analysis reports. Project specific documents, such as risk assessments and method statements, are also made available via this reporting platform.

Delivering Time and Cost Savings

Working with SOCOTEC as a single sub-contractor across multiple specialist preconstruction and construction services has provided a number of benefits to the Contractor, including time efficiencies and cost savings.

Michael Astley-Heilbronn, Senior Site Agent for BAM Nuttall Ltd, has been working closely with SOCOTEC on this project and comments:

The Newhaven Port Access Road project is an excellent example of how working with a single contractor to deliver multiple specialists services can deliver time efficiencies and cost savings for a client.