Cromwell Geobag Removal and Pond Desludging

⁠⁠⁠Overview

The Central Otago District Council is inviting proposals from experienced and qualified contractors for desludging two oxidation ponds at the Cromwell Wastewater Treatment Plant (WWTP).

About

The Cromwell ponds were previously desludged in 2017. Further sludge surveys conducted in 2026 confirmed the need for intervention.

Purpose

Desludging is a routine but infrequent maintenance activity essential for maintaining the treatment process.

Scope

The scope includes:

• Removal of the existing sludge stored in Geotextile bags (Optional Separable Portion)
• Design of a sludge removal methodology, dewatering basin and monitoring programme
• Desludging of the two oxidation ponds
• Dewatering of the dredged sludge using suitable technology

This procurement specifically covers the desludging and dewatering components. Disposal of the dewatered sludge and the new geotextile bag are excluded from the contract works.

Instructions to Tenderers

Further information is provided in the RFP document.

Location

• Facility: Cromwell Wastewater Treatment Plant (WWTP)
• Map: View on Google Maps