Selwyn District Council

SDC25/26-3 - Desludging Victoria Road Wastewater Ponds - RFP

Stratford District Council operates a Wastewater Treatment Plant at 47 Victoria Road, Stratford to service the Stratford township. This s a crucial component of the town’s infrastructure, primarily servicing a residential population of approximately 6,500 people.
The system also processes wastewater discharge from several local commercial and light industrial businesses and a dump station on Esk Road.
The plant's overall function is to convert raw influent into treated effluent using a multi-stage pond system.
The facility consists of one main wastewater stabilisation pond (Pond 1) and three smaller maturation ponds.
Pond 1 is intended to operate at a depth of 3 to 4 metres when free of biosolids.
Recent investigations have identified a significant build-up of biosolids that is affecting treatment performance. The four aerators within Pond 1 (two on each side) have contributed to uneven circulation, leading to biosolids accumulating around the pond edges and forming a central island. This has reduced
the effective depth in parts of the pond to around 1 metre or less.
Biosolids were last removed in 2004 by dredging and pumping into permeable geo-textile bags, which were then placed on an adjacent historic landfill site. After a drying period, the biosolids were spread over the landfill, capped, and returned to pasture.
Although Stratford District Council has obtained resource consents from the Taranaki Regional Council to repeat the previously used desludging method, Council is open to alternative methods that will achieve the same outcomes.
Accordingly, this Request for Proposal includes the following key components:
1. Preparatory the historic landfill site
2. Excavating biosolids from Pond 1
3. Dewatering the biosolids
4. Spreading the dewatered biosolids
5. Capping and reinstating the landfill site
The Contractor is responsible for planning, executing, and monitoring all aspects of this project in strict accordance with the issued resource consents.

Department/Business Unit: Assets