PP O’Connor has been appointed by Celtic Technologies to carry out the bulk earthworks, remediation and ground stabilisation required for the enabling works on the £170m Davyhulme wastewater treatment plant upgrade.
Celtic-Englobe was awarded the £5.5m enabling works package in March.
PP O’Connor’s role is to manage the asbestos risk and segregate soils that are geo-technically and chemically suitable for use without further treatment. It will treat otherwise unsuitable soils or other excavated materials to render them acceptable for reuse on site. All technical assistance, pre and post validation testing, monitoring, statutory licencing and gaining of permits etc will be undertaken by Celtic Technologies.
The main focus of the enabling works is to excavate, sort and remediate historic screenings and varied made ground, sludges and other arisings previously tipped from historical developments. Some soils may be treated by stabilisation. It is anticipated that some concrete/brick rubble will also be excavated as part of enabling works and some of these arisings will require crushing before they can be re-used within the works. T
he works generally involve sorting, processing and re-engineering in the region of 250,000m3 of the existing topography to provide three engineered piling platforms and an early surcharge mound in the region of 100,000m3 of processed material to ensure proper settlement of deep silts located in the area of an old river bed.
In conjunction with the earthworks, Celtic will also be carrying out additional works relating to the removal of several redundant deep digester tanks and the potential treatment of any resultant sludges. Finally, piling platforms are to be stabilised and imported aggregate piling mats placed prior to final handover for the actual construction works.
The Davyhulme treatment plant is the largest in the northwest and serves a population of more than a million people. The upgrade is expected to improve the quality of water entering the Manchester Ship Canal and take 36 months to complete.