Case Study Depots

Investigation and Testing of Highway Maintenance Depots

Client: Highways England and Local Councils

Location: Throughout the UK

Maintenance depots are a key asset for Highways England and Local Authorities strategically located throughout the UK and used predominantly for routine road maintenance operations including gritting and snow removal and provision and storm drain maintenance. Many depots have facilities for storing and maintaining plant and equipment along with fuel.

In addition many depots also store materials including road salts and also materials removed from the motorway for waste and recycling including asphalt, soils and drainage media.

Nicholls Colton Group provides a complete service for the upkeep of the depot assets and compliance with environmental management plans. Throughout the UK we routinely undertake a comprehensive range of investigations including: investigation into salt barn condition, investigation of buildings, monitoring of salt stock, monitoring of waste including run off water, asphalt planning’s, gully waste and settling ponds. More recently we have completed a number of site investigations to provide geotechnical characterisation of existing sites with historical data where historical data could not be found.


  Salt Barns

Chemical reaction between road salts and reinforcement in concrete is a common cause of corrosion and structural failure. Nicholls Colton undertake investigation and testing to salt barns throughout he UK identifying and quantifying defects, undertaking condition testing of the concrete and chemical analysis of samples in our UKAS* accredited laboratory.

The Service Provider must routinely perform strategic rock salt Stock monitoring during the winter period and report salt stock capability levels as part of the established daily winter service reporting procedures using the on-line electronic reporting system, WRF1. Daily reporting must commence on 1 October and end on 30 April.

Nicholls Colton provide analysis in compliance with BS EN 3247, testing for moisture, chloride, insoluble material, sulphate and anti-caking.


Building Maintenance

The structural assets of council depots are often aged and have historically been poorly maintained and were not designed for the requirements of 21st century maintenance. Nicholls Colton undertakes a series of investigations and tests to determine the structural design and condition by non destructive methodology wherever possible.

Nicholls Colton undertakes sampling and testing of water storage tanks and systems in accordance with BS 7592:2008 “Sampling for Legionella bacteria in water systems – Code of Practice and provide a detailed report to facilitate compliance with the Environment Management Plans.


Waste and recycling

The removal of materials from highway infrastructure and storage for recycling or waste disposal requires environmental management. Nicholls Colton undertakes comprehensive sampling and analysis of all waters, soil, aggregate, asphalt and recyclable materials including the following:

  • Monitoring storage tanks including discharge to foul sewer and surface waters
    • Screening and analysis for recycling or disposal
    • Monitoring against site specific utility company “Discharge Consent” requirements
  • Gulley waste
    • Screening and analysis for recycling or disposal
  • Material recycling planings / scalpings
    • Tar analysis compliant with ADEPT / County Surveyors Report
  • Waste Acceptance Criteria
    • WAC Analysis
    • Solids Suite
    • EWC classification
  • Asbestos screening of all recycled materials in our *UKAS accredited laboratory.
  • Technical Guidance WM3 significantly
    • C16 Assessment of Persistent Organic Pollutants
  • Environmental monitoring of dust, noise and vibration


Drainage Survey

Nicholls Colton’s teams are available to assist with all aspects of drainage at depots; from maintenance works to investigating and rectifying issues with drainage on site. Routine maintenance of the drainage at depots is important in ensuring there are no issues that could affect the day to day operation of the site.

Our team has recently investigated a surface water system at a depot in London, having been called in to assist with investigating flooding around the storage areas of the depot. Initially the local road gullies connecting into the system were pumped clear using a vacuum tanker as they were completely blocked. The system was then thoroughly jetted before being CCTV surveyed by our qualified Engineers, assessing both the layout and condition of the system through to its outfall into a local tributary.

The investigations showed the system had been poorly maintained, with aggregates and coarse debris washed into the system impeding the flow and causing the pipework to back-up; consequently, during periods of rainfall there was localised flooding. Nicholls Colton identified and rectified the issue through the investigation works, reporting to the client via our web based portal and giving our client access to a detailed report with recommendations and CCTV footage within 48 hours of completion of site works