Project Overview

The Lochaline WTW was identified for replacement with a membrane treatment plant as part of the Scottish Water SR15 Water Quality Enhancement Intervention Programme due to the risk of water quality failures and growth in demand in the local supply zone.

An effective cryptosporidium barrier was required at Lochaline WTW. To achieve this a Nanofiltration (NF) Membrane based process was installed adjacent to the existing plant. The maximum raw water flow to the works was 90m³/day during Phase 1 of this project, however the NF plant delivered during this phase, was sized to deliver the full Phase 2 (Growth) deployable output of up to 195m³/day.

Through Scottish Water’s Non-infrastructure Alliance with ESD, Ross-shire Engineering (RSE) was engaged to design, manufacture and install a 195m³/day Nanofiltration modular and Transportable Treatment Unit (TTU) membrane plant operating at 85% recovery, on the Lochaline site.

Phase 1a of the project included Inlet Strainers, Membrane Feed Pumps, Recirculation Pumps, Nanofiltration Membranes, CIP facility, Sodium Hypochlorite dosing, Chlorine Contact Pipe, Re-mineralisation Tank, Chemical Waste Tank, Site Motor Control Centre, Software and System Integration, Instrumentation, Telemetry and Welfare Facilities, all housed within the TTU. Other work included a new raw water main, dechlorination chamber, standby generator with power auto-changer panel, a treated water pumping station and a new water main.

Phase 1b of the project included a new 146.3m³ capacity Clear Water Tank (CWT-1)

Phase 2 (Growth) will involve the construction of a new Service Reservoir and changes to the Treated Water Pumping Station installed under Phase 1b.

Ross-shire Engineering’s in-house design team transforms a Water Treatment Works concept in to a detailed BIM Level 2 design. Our Design for Manufacture & Assembly (DfMA) process enables a seamless transition from design in to fabrication and modular assembly within our specialist facilities.

We have control over every aspect of the modular plant delivery process with design, fabrication and assembly within walking distance. Having all our facilities in the same location saves time compared to a traditional in-situ construction of a new water treatment works.

Our in-house BIM design capability and DfMA approach to Modular Off-site construction allows us to support our client’s internationally.

The units can be closed, fully clad, sealed and ready to be shipped by road or boat to anywhere in the world. This philosophy is scalable and is something that RSE are continuously developing.

Following testing and commissioning the Lochaline plant is separated into its four modules and carefully prepared for the 118 mile journey by road to its permanent home via the A9, the A82 and the Corran ferry crossing.

Membrane Cleaning

• Foam Ball Cleaning - Yes
• Frequency - Daily (Every 4 hours; duration 10 minutes)
• Frequency of CIP Cleaning - Every 3 months
• Chemicals used for CIP cleaning - Citric Acid / Sodium Hypochlorite

Sodium Hypochlorite Dosing

PSI adopted a pioneering approach which led to bringing the main process line within the dosing unit, negating the need for extensive pipework runs and reduced the installation and maintenance requirements.

Chlorine Contact Pipe (CCP)

The Chlorinated Water flows through the Chlorine Contact Pipe (CCP) to ensure that there is the required contact time for disinfection. Incorporating the CCP within the modular construction has reduced the amount of civils work on site.

Waste Water Tank

The Waste Water Tank has been incorporated within the modular structure, which has allowed it to be constructed in steel and reduce the amount of civil work on site.

Laboratory and Welfare Facilities

Quotes

The project was successfully completed on time, defect free with acceptance from Scottish Water. Scottish Waters Customer Service Delivery (CSD) operatives are pleased with the new plant’s performance, see post below from Douglas Millican, Scottish Water CEO, following a recent visit to the site.

Jeff Forrester - ESD, Delivery Project Manager

Challenges to a project like Lochaline are disruption to the local community which we want to keep to a minimum. The advantages of a Transportable Treatment Unit (TTU) is that the programme is reduced, management of traffic is reduced to a minimum and there is less disruption to the local community, this is very important as it allows them to be engaged and on board with the project. This has been very successful on the Lochaline project. Residents live very close to the site, keeping them engaged allows them to see the time scale for disruptions has been vastly reduced due to the method of constriction that was chosen."

Paul Gerard – ESD – Design Lead & Process Engineer

The Lochaline WTW was awarded to ESD from SW in May 2016. With the assistance from RSE, the design was agreed, developed and a full working solution was delivered to site within 8 months in January 2017. The project rocketed along at a very high speed and worked first time. This was only through the strong collaboration between ESD, SW and RSE Design and Delivery teams. The early engagement with RSE has allowed the innovative modular approach to water treatment and has transformed the industry, especially in more remote locations. Lochaline is a successful example of supply chain collaboration, working together to provide a positive and successful outcome for SW and their customers. The challenges on this project were the time frames due to the water quality at Lochaline, the site size and location."

Gavin Steel - Scottish Water’s Regional Communities Manager for the Highlands

This project is a great example of Scottish Water, ESD and Ross-Shire Engineering working together to deliver a positive result for our customers."