Project Introduction

Coleman Construction & Utilities Limited has completed a civil engineering sub-contract for Principal Contractor CMDP JV, on behalf of Southern Water. The works encompassed a new WTW Ferric Dosing package, which comprised of demolishing existing bases, bulk excavation for pile mat, pinpointing all services so we could coordinate trades and ensure that the piles would not interfere with existing services, a new interceptor chamber, pipework and drainage, extension of a roadway and provision of hardstanding’s, site wide ducting, draw pits and new reinforced concrete structures, including a new chemical dosing bund with 500mm base. The walls where formed by using a Peri duo lightweight system which is easily handled, there was also kiosk bases and a shower base plus a road bunded area and road widening.

The contract was underpinned throughout by a collaborative approach with CMDP JV and Southern Water, as well as other project stakeholders, providing the basis for proactive communication and highly coordinated activities, resulting in the safe and successful completion of this wastewater civil engineering project – meeting time and budget requirements.

Project Deliverables – Civil Engineering Scope

Chemical bunded tank with integral plinths works:

• A 16m x 6m x 1m deep stepped excavation to accommodate the pile mat and avoid temporary works whilst finding the services.
• 6.5 tonnes of rebar were fixed into position to reinforce the 350mm deep concrete base.
• 38m3 of concrete was poured for the base using a 24m concrete pump and then finished by hand.
• Construction of reinforced concrete walls using ‘Peri’ duo formwork.
• Plinths were cast in the bund for the storage tanks and pipe work.

Interception chamber works:

• 3m deep excavation works using a 14-tonne machine.
• Temporary works installation, using a manhole box.
• 1.2m diameter concrete rings lifted in position using a 14-tonne machine to create a 3m deep chamber.
• Groundwater management.

Tertiary area works:

• Installation of 70m of 150mm soil pipe.
• 2No cable draw pits installed.
• 165m of connecting ductwork.
• Concrete bases constructed for caustic dosing kiosk, fibre node box, shower base and tank filling cabinet.

Chemical road bund and road widening:

• A chemical road bund was formed for the containment of any future spills.

Challenges and Solutions

• The biggest challenge was a problematic pressurised wash water main that was very old and fragile. After repairing it several times, due to it failing somewhere else, it was decided to replace and re-route it.
• Congested areas of works within all new pipes, manholes, ducts, draw pits and chambers joining together, were managed through regular programme and sequencing reviews to enable all works to be carefully planned. 
• Deliveries were part of a co-ordinated plan of plant and equipment logistics to ensure works kept on track.
• Interface with other contractors/stakeholders included collaborative early engagement meetings, regular planning, and liaison through weekly project meetings.

Benefits

• Coleman Construction & Utilities Limited provide a non-confrontational approach to commercial and contractual matters, preferring to work collaboratively in the interests of the project. As a result, working relationships with the client at all levels and across all disciplines are at an all-time high.
• Collaborative working has become a daily norm for Coleman Construction & Utilities staff. We always offer a solution-based approach.
• We are always striving for best practice working especially where health, safety and wellbeing are concerned – we aim for zero harm every day.
• We take pride in our work and aim to leave our sites snag free. Our attention to detail is second to none.