Little Stanney Filtered Water Pumping Station Mechanical Installation

The Galliford Try, Costain, Atkins (GCA) Joint Venture are currently working on behalf of United Utilities (UU) at Little Stanney WTW in Cheshire.  As part of this main contract Franklyn Yates Engineering have been awarded the mechanical works on the new Filtered Water Pumping Station.

Brief Outline of the Project

Since around 1996 United Utilities (UU) has had a contract to provide Intergen PLC with a supply of industrial grade water for use as cooling water at Rocksavage Power Station.

UU constructed a new treatment plant called Little Stanney WTW for this sole purpose, located on Ellesmere Port WWTW. Water was abstracted from the River Dee at Heronbridge Pumping Station, transferred via a pipeline for treatment at the new works and the treated water pumped on to Rocksavage Power Station.

The works is currently unable to provide water at a turbidity consistently below 5 NTU, leading to the customer using a potable water supply instead. As a result of this, the plant has been operated intermittently at reduced flows and performance levels. At present, the chemical dosing systems at the plant are not used and the plant does not operate during periods of poor raw water quality.

This scheme is to address the problem by the installation of a new treatment plant.

Scope of Works & Responsibilities

The works consist of the design, specification, manufacture, supply, witnessed works inspection & testing, delivery, off-loading, lifting, positioning, installation, equipment asset labelling, tagging, on-site testing and commissioning and 'as-built' drawings of all installed equipment to provide the Filtered Water Pumping Station Mechanical Installation at Little Stanney WTW.

Mechanical Installation Scope

The work is to be carried out in three phases. This is necessary due to the long delivery period of the replacement pumps and the subsequent need to have a temporary pumping system working.

Phase 1: Equipment removal and valve replacement

• Disconnect pipework between pumps 1 and 2 inlet and discharge isolation valves and remove to a designated area local to the pump slab. These pipes are to be refitted when the new pumps are installed
• Disconnect and remove to a local designated area the two 500nb and two 400nb gate and non-return valves in pumps 1 and 2 flow streams
• Disconnect and remove to a local designated area the 200nb gate valve and relief valve located in the pressure relief line
• Survey the flange position/elevation of the two pump sets and record the data. Unbolt from the concrete base the two pump sets and remove to a local designated area
• Receive and offload the replacement valves: two 500nb gate valves, two 400nb gate valves, two 400nb wafer pattern non-return valves, one 200nb gate valve, one 200nb relief valve, one 25nb ball valve and one 25nb air release valve
• Install all valves with the exception of the two 400nb non-return valves

Phase 2: Pump installation plus pump 1 pipework

• Receive, offload and install the two replacement pump sets. These must be shimmed, levelled, and positioned to the same datum as the existing pumps
• Reinstall the pipework to pump 1 stream, including the new 400nb non return valve

Phase 3: Pump 2 pipework installation

• Reinstall the pipework to pump 2 stream; including the new 400nb non-return valve

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