The Ashford Consent Compliance Scheme is the first of three projects at Southern Water’s Ashford Wastewater Treatment Works to reach completion according to leading engineering, consulting and construction company Black & Veatch.

Forming a part of 4Delivery’s East Kent Sludge Framework, the Ashford Consent Compliance Scheme is quality driven and produces effluent to a higher standard, thereby improving the overall quality of the water in the Great Stour River. The Ashford consent compliance scheme was driven by changes to consent levels for the Ashford Wastewater Treatment Works. The critical new summer consent levels of 20mg/l SS, 10mg/l BOD and 3mg/l NH3 were applicable from 1st October 2007, and the new Tertiary Treatment Plant had to be ready to meet the new requirements.

4Delivery augmented its delivery team by formulating packages of work and letting them to key subcontractors. These are referred to as Tier 1 contractors, where Tier 1 subcontractors replace the Costain construction team and run the projects using their own management systems. Tier 2 subcontractors work directly for 4Delivery and are managed by the Costain construction team. The Tier 1 contractors work closely with the design team as responsibility for design, excluding package plants, rests with 4Delivery.

Black & Veatch constructed and commissioned the project for client 4Delivery, a Special Purpose Vehicle set up by suppliers to Southern Water to assist in the delivery of Southern Water’s current capital programme. 4D is responsible for the project management, design and delivery of schemes including:·  

• Widespread improvements to sewage works to upgrade the quality of water released into rivers and the sea
• Refurbishing water supply works to improve the quality of tap water
• Schemes to help safeguard water supplies
• An £80 million programme to help protect homes from flooding from sewers
• Projects to control odours from treatment works
• Schemes to provide mains drainage to areas without public sewers Work to start addressing
• Government plans for new house building in the South-East.           

 Commenting on the scheme, Martin Charlton, Director for Black & Veatch Water Europe’s Southern Project Centre, said: “The East Kent Sludge Framework is the combination of projects at Ashford, Allington and Aylesford. It is a great achievement to obtain completion of one of the larger and key schemes, Ashford Consent Compliance. This scheme has been very challenging with aggressive timescales. Despite these challenges, the Black & Veatch team has completed this project to the agreed timescale and developed innovative and sustainable solutions to construction and commissioning issues.”

Geoff Joy, Southern Water’s Sludge Treatment Centre (STC) Section Leader at Ashford, remarked, “The whole project was conducted in a very professional manner with Black & Veatch providing continuous support and resolutions to problems as they arose. Teamwork between Southern Water, 4D and Black & Veatch was paramount to the successful outcome of this project with as little interruption to the operations on site as possible.”

Greg Mullett, Project Manager for 4D, said: “The Ashford Project team won 4D Team of The Month for November 2007 for successfully carrying out work to achieve consent. The team worked incredibly hard to secure the performance of the plant when the consent for ammonia had to be reduced significantly. This was an excellent example of teamwork between Southern Water Operations, 4Delivery and Black & Veatch. Performance of the plant since takeover has been excellent.”

Black & Veatch’s role in £5.8 million ($11 million) Ashford Consent Compliance Scheme involved providing:

• ·         Three new Nitrifying Tertiary Filters (NTF) – each 20m diameter with a retained height of 5.5m plastic media.
• ·         New six lane Deep Bed Sand Filter (DBSF) – each lane 13m long by 3m wide by 5m high, along with a dirty wash water tank and filtered effluent tank.
• ·         New combined NTF Feed, Re-circulation and DBSF Feed Pumping Station. The overall dimensions were 17m by 6.5m by 6.5m deep with 5.4m below ground level.
• ·         New high voltage power supply, electrical installation and control system. The scheme required a new 450m run of 11KV cable, a new 11KV switchboard, a new 800 Kilovolt-Amps (KVA) transformer and dedicated Motor Control Centres (MCC) for the pumping station and the DBSF.
• ·         New standby power supply generator and fuel storage – the generator is rated at 630KVA with a fuel tank sufficient to allow 80 hours running time.
• ·         Various elements of interconnecting pipework