Sewage Treatment Works, Dorset

Aarsleff Ground Engineering were awarded the piling contract by Wessex Water, for the extension of Gillingham’s Sewage Treatment Works (STW) in Dorset.

Gillingham STW is located approximately 580m south west of the centre of Gillingham and 1.45km west of Ham common and serves a population of 15,100. An extension to Gillingham’s STW is required to provide additional plant and equipment to treat an increased volume of wastewater, and installation of phosphorous removal plant.

The site, which is triangular in shape, comprised a mixture of grassed areas, gravel, concrete hardstanding and STW infrastructure. The south eastern boundary of the site is defined by a row of trees beyond which lies a railway track. The site is located
on superficial deposits comprising both Alluvium and Head deposits, characterised by clay, silt with sand and gravel appearing in the Head Deposits. The underlying bedrock is shown to comprise Kimmeridge Clay Formation of Jurassic age, defined as calcareous
mudstone with occasional thin siltstone beds.

Aarsleff commenced on site in early September 2018, installing 303No. precast concrete piles with its Banut 300 rig, ideally suited for restricted access sites. The piles were 250mm square section and between 5-13m in length, designed to cater for up
to 455kN compressive working loads. All piles were manufactured in Aarsleff’s sister manufacturing facility Centrum Pile and were therefore tested and confirmed as structurally competent before delivery to site.

Aarsleff’s Simon Cottington commented, “This project went smoothly from beginning to end and we worked well with Wessex Water to ensure successful delivery on programme and within budget. Site preparation from Wessex Water meant that there were no delays
and we could carry out a thorough probing exercise across all areas far enough in advance. We look forward to working together again next time round. ” Aarsleff completed the pilings work on the 24th September 2018.