What we do Construction support

Construction phase support

Lithos are able to help with ground-related problems that sometimes arise during the construction phase of a project.

Where surplus arisings cannot be accommodated on sites, our engineers can sample stockpiles, schedule appropriate testing, and then provide advice with respect to waste classification or suitability for transfer to other development sites (see Materials Management Plans).

Disposal of surplus made ground, or contaminated natural soils, to landfill may be the only practicable solution if redistribution and retention on site is not feasible or earthworks generate a surplus. Characterisation, sampling and classification of soils arising from brownfield sites has been incorporated within the Environment Agency’s Technical Guidance WM3 (“Guidance on the classification and assessment of waste” version 1.1. Environment Agency 2018). Classification of soils in accordance with WM3 is quite a complex process, although it ultimately results in a simple classification as hazardous or non-hazardous.

If waste soil is classed as hazardous following classification under WM3, and destined for landfill, waste acceptance criteria (WAC) leachate testing will need to be undertaken.  Similarly, if waste soil destined for landfill is classed as non-hazardous under WM3, and suspected to be inert, WAC leachate testing will need to be undertaken.

It is critical that material to be exported from site is allocated an appropriate waste code, following the 7 steps within WM3.  Waste carriers transporting, and sites accepting, this material should have a corresponding code within their permits.  Under the Waste Duty of Care Code of Practice, it is the responsibility of those generating the waste (i.e. the site), to ensure that the waste is handled and disposed of appropriately.  However, Lithos are able to undertake the necessary assessment on the developer / contractor’s behalf and produce a comprehensive report that clearly shows each of the seven steps have been followed.

Lithos can review existing data (including previous site investigation reports) in order to highlight key ground-related issues that require pre-tender consideration.  We also provide telephone support and answer e-mailed queries during the tender period, and can attend meetings as required.

Our qualified geotechnical engineers can visit site to inspect and advise on a variety of issues including: suitable founding strata; foundation depths; highway formation etc.

Post-construction Lithos can provide advice relating to geotechnical failure for issues such as: general site subsidence; collapsed mine workings; and building subsidence.

Whilst each situation requires a bespoke approach, concise engineering reports are typically issued that provide an opinion on the cause of the problem, its severity and potential solutions.

Where required, Lithos can undertake ground monitoring to gain data on a specific problem, and can assist the Structural Engineer with the engineering design of the remedial solution.

Current guidance requires at least some degree of independent certification on all developments where gas protection measures are required.  The frequency of independent inspections required will vary depending on the level of risk, the type of construction and whether the protection is being installed by a specialist contractor.

Our engineers are fully conversant with the latest guidance on the design and installation of gas protection measures to all forms of building structure.

Typically, inspections are required at two key stages during construction:

  • Creation of the sub-floor void
  • Placement of the gas resistant membrane

Validation certificates, verifying that the required protective measures have been installed correctly, are issued as development proceeds to enable finalling of plots under the CML initiative.

Almost all residential redevelopment on brownfield land requires placement of a clean soil cover layer in garden and landscaped areas, usually to form a barrier between residents and residual contamination in the ground.

The Council of Mortgage Lenders requires house builders to submit a validation report to the warranty provider confirming the thickness and quality of the soil cover.  Lithos provides a proactive service with quick turnaround for validating the placement of soil cover.  We employ qualified geoenvironmental engineers who have extensive experience in the sampling of soil cover material to assess suitability.  We issue concise validation certificates to gain approval from warranty providers and regulators as efficiently as possible.

Where sites are located in areas of high environmental sensitivity, e.g. Groundwater Source Protection Zone 1 or adjacent to a surface watercourse, our qualified geoenvironmental engineers can undertake site audits to ensure that works are being undertaken in accordance with the Construction Environmental Management Strategy (CEMS) and Construction Environmental Management Plan (CEMP) and general best practice. Lithos can also prepare the CEMS, but the CEMP should be prepared by the Principal Contractor, taking account of the CEMS.

Lithos also prepare surface water management plans and undertake regular sampling and analysis of surface watercourses adjacent to and downstream of construction sites, to ensure that the watercourse is not being contaminated by site run-off.