Strategic West Coast Pumping Station Location Briefing

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Introduction

A planning application has been submitted by the Isle of Man Water & Sewerage Authority for a new potable water pumping station to be constructed on the land of Mr Pheric Curphey at Ballanea Farm, Ballaleigh, Kirk Michael. This briefing paper details the exercise undertaken to determine the optimum location of the pumping station in terms of operation and value for money.

Background

Independent risk studies have identified security of supply issues for the Southern Supply Zone in the event of problems at Douglas WTW and during peak water demand conditions forecasted in year 2021.

To alleviate these risks, a pumping facility is recommended to be constructed on the West Coast Trunk Main south of Kirk Michael, which in conjunction with the refurbished St John’s Pump Station will allow a 5 megalitre per day (mld) north to south transfer.

The benefits of the 5mld transfer are;

• Security of supply maintained to the Southern Zone in the event of supply difficulties at Douglas WTW.
• 5mld transfer to the Southern Zone when the Island reaches increased water demand conditions forecasted for year 2021
• Reduced use of the Beinn-Y-Phott rising main and pumps during drought conditions (as experienced this year)
• Increased flow through Sulby WTW to provide greater pay back from the energy recovery turbine

All key Authority stakeholders are in agreement that construction of the strategic pump station on the West Coast trunk main should proceed without delay.

Pump Station Location

Hydraulic modelling studies have identified a section of trunk main south of Kirk Michael approximately 2km in length that is suitable in terms of hydraulic profile for the position of the pump station.

Within this section of pipeline a number of possible pump station sites were identified. Of these possible sites one field in particular was selected due to its proximity to an MEA sub-station. All other sites would need a new sub-station at a cost of approximately £70,000.

Within the chosen field one particular location has the benefit of an existing access, being relatively flat and reasonably out of sight of the main road. The land is currently used to store what looks like waste building material. Initial discussions with the Planning Department have indicated that gaining planning approval should not be a significant issue for this site.

An alternate location within the same field was considered, but discounted due to the additional civil engineering works required due to the topography of the site and lack of existing access, which would cost approximately £50,000.

Decision	Appell	STRATEGIC WEST COAST PUMP TRANSFER SCHEME	LOCATION BRIEFING PAPER

Proposed pump station location

Alternative site location requiring deep & extensive civil engineering works

Proposed site location with existing access track, flat topography & close proximity to MEA sub-station

Conclusion

This pumping station is of critical importance for the future supply of potable water around the Isle of Man, and must be progressed.

As a Statutory Board of the Isle of Man Government the Isle of Man Water & Sewerage Authority has a responsibility to ensure best value is achieved on all Capital Projects, and hence the chosen location, being £50,000 less than any alternative is the preferred option.

The nature of the proposed installation is such that it is considered to have minimal impact on local residents. The land is not zoned for residential development and it is unlikely that planning permission would be granted in the future for any such development. The site's proximity to an MEA sub-station and gas facility has the advantage of keeping such apparatus in one area of this rural landscape.