Project:

Liverpool Festival Gardens

Date:

2021-2023

Location:

Liverpool, UK

Client:

Vinci Construction/Liverpool City Council

Business Sectors:

Site Remediation

Services (Technical Disciplines):

A former  oil terminal was situated within part of the site which required careful removal of  underground pipe infrastructure and oil recovery from ground using skimmer systems and use of a water treatment plant prior to discharge to foul sewer under a Trade Effluent Discharge Consent.

Settlement risks were mitigated via a combination of rolling dynamic compaction to improve the wastes and engineering of general fill materials (including the use of lime to improve moisture content of the fill) to construct a development platform.

VertaseFLI operated under a number of Environmental Permitting regimes.s. Suitable materials were reused under CL:AIRE DoWCoP Materials Management Plan as agreed with the regulators.

By virtue of its thickness and poorly characterised composition, it was recognised early in the project that earlier fill posed a potential risk of long-term creep settlement, even after improvement by rolling dynamic compaction. To better characterise this risk, VertaseFLI developed a long-term settlement model for the material and an innovative method of verifying the input parameters using rod-type borehole extensometers. The innovative verification method provided evidence to stakeholders that unacceptable magnitudes of settlement over the design lifetime were unlikely.

Following removal of waste materials from the site area Rolling Dynamic Compaction was undertaken to an effective depth of approximately 3m prior to filling works commencing. Filling operations were undertaken in accordance with a stringent specification and overseen by the client’s consultant throughout the works.

Approximately 700m of 2.4m diameter deep attention drainage was  installed throughout the course of the project alongside shallow drainage.

Project Objectives/Outcomes:

To implement an outline remediation strategy developed by Arup to prepare the 10-hectare development zone of the former Liverpool Festival Gardens site for mixed residential and commercial development.

The Site had been historically reclaimed from the estuary of the river Mersey by progressive land raising above the tidal flat deposits via the deposition of various waste materials. Wastes tipped pre-1962 comprised sandstone rubble and dock waste. Wastes placed between 1978 and 1981 comprised commercial, industrial and domestic waste before landscaping the site using surplus soils from nearby developments termed the International Garden Festival Fill.

Our Role:

Excavation of landfilled commercial and industrial waste, Processing of the waste to separate undesirable materials for disposal, Oil recovery, Installation of deep drainage, Earthworks to construct landscape features and construct a development platform, Lime improvement, Dynamic compaction, Settlement modelling and model verification using extensometers, Regulatory consultation, Ground gas monitoring, Geochemical and Geotechnical verification.

Geoscience Ireland Contact: Alex Flynn aflynn@fli-group.com