THE MODULAR WATER

WATER TREATMENT

LOCHALINE WTW TTU

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CASE STUDY

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Project Title: Lochaline WTW (TTU)Client: ESD ESD (a JV Alliance between B&V, Stantec and Galliford Try) for Scottish WaterProject Value: £3.1MDesign Start: 8th July 2016Manufacture Start: 18th July 2016Delivery to Site: 1st March 2017Commissioned / WIS: 31st March 2017Works Address: Lochaline, Oban, PA80 5UY

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.

Project Overview:

Fig 1 - Works location map

Lochaline WTW

Isle of Mull Oban

Lochaline - The existing Water Treatment Works site prior to the construction of the new works.

Case Study / Lochaline WTW TTU

RSE’s modular TTU product range allows us to facilitate a quick turnaround of our Client’s scope requirements, in to a detailed BIM design and through manufacture within our state of the art off-site modular assembly facilities.

An innovative design approach was required due to site topography and access constraints, this allowed for the incorporation of a modularised welfare unit to accommodate all of Scottish Water’s operational requirements and has been well received by our clients.

Utilising our group manufacturing capability ensures a collaborative approach for our clients. As Principal Contractor, RSE also manufactured and produced the TTU. Ross-shire Engineering’s specialist chemical dosing company PSI were engaged to design and manufacture a modular solution for Sodium Hypochlorite disinfection. PSI adopted a pioneering approach which

Project Overview:


Lochaline TTU Floor plan

led to them bringing the main process line within the dosing unit, negating the need for extensive pipework runs and reduced the installation and maintenance requirements.

The TTU was designed and assembled at Ross-shire Engineering’s Modular Facility of Excellence base in Muir of Ord, before undergoing comprehensive testing.

We offer a unique and unrivalled service for our clients with design, manufacturing, assembly and off-site testing all delivered within our Muir of Ord Modular facility of excellence. As our company has grown so has our facilities and our innovative thinking challenging convention of what

can be delivered off-site. What would have been traditionally delivered as an in-situ civil solution - like the chemical contact pipe and bulk waste tank, have now been incorporated in to our off-site modular package. This enables the complete water treatment works to be manufactured and assembled in a controlled environment. Once off-site testing and commissioning is complete we separate the units, mobilise to site and complete final site testing and commissioning comfortable in the knowledge that the turn key solution will work first time and provide maximum customer satisfaction.


Lochaline WTW – 3D Elevation

Lochaline WTW – 3D Section

Lochaline WTW – 3D model


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.

Water Quality Tables


Parameter Unit No. Samples Maximum Mean Minimum 95%ile

Colour Deg Hazen 53 90 11.1 2 29.9

Conductivity μS/cm at 20°C 4 89 82.3 78 88.1

Hydrogen Ion pH value 32 7.8 7.5 7.2 7.7

Suspended Solids Mg/l 4 4.0 3.3 2 4.0

Total Organic Carbon Mg C/l 29 4.5 1.6 <0.5 3.8

Turbidity NTU 48 2.4 0.4 0.2 1.4

UV Transmittance % 29 96.4 85.7 55.2 95.7

Bromide μg Br/l 2 48 43.3 38.6 47.5

Aluminium μg Al/l 29 121 51.3 11 97.2

Dissolved Iron μg Fe/l 2 93 63.5 34 90.1

Iron μg Fe/l 49 299 55.9 <7 164

Manganese μgMn/l 51 11.7 1.9 0.7 5.6

Presumptive E. Coli CFU in 100ml 32 220 18.1 0 102

Presumptive Coliforms CFU in 100ml 32 1600 235 6 632

Raw Water Quality Envelope (Alt Achad Forsa – raw water source)

The raw water treatment plant and in particular pre-treatment, NF membranes, CIP and post treatment re-mineralisation were selected based on suitability for operation to treat the following raw water quality envelope.

Note:- ‘<’ denotes laboratory detection limit.

Parameter Unit RSE Target The Public Water Supplies The Water Supply (Scotland) (Water Quality) (England & Wales) Regs 2014 No. 364 Regs 2016 No. 614

Colour Deg Hazen 5 20 20

Total Iron μgFe/l 50 200 200

Total Manganese μgMg/l 10 50 50

Total Aluminium μgAl/l 50 200 200

Total Organic Carbon mgC/l 2 No abnormal change No abnormal change

Total THM μg/l 40 100 100

Turbidity NTU 0.4 4 4

Free Chlorine mg/l 0.2–2.0 - -

Hydrogen Ion pH Value 7.8-9.2 6.5-9.5 6.5-9.5

Water to Supply – Treated Water Quality Targets

Parameter Unit Minimum Maximum Mean 95th Percentile Count

Colour Deg Hazen <2 2 <2 <2 36

Hydrogen ion pH value 7.8 7.9 7.8 7.9 7

Turbidity NTU <0.2 0.2 <0.2 <0.2 36

THM: Total mg/l <3.2 10.7 6 9.2 34

Aluminium μgAl/l 9 20 13.5 18.5 36

Iron μgFe/l <7 13 <7 <7 36

Manganese μgMn/l <1 <1 <1 <1 36

Coliform bacteria cfu/100 ml 0 0 0 0 30

E. coli cfu/100 ml 0 0 0 0 30

Treated Water – Performance Test Results



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

Membrane Cleaning

Chlorine Contact PipeThe 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

Laboratory and Welfare Facilities

Sodium Hypochlorite dosingPSI adopted a pioneering approach which led to them bringing

the main process line within the dosing unit, negating the need

for extensive pipework runs and reduced the installation and

maintenance requirements.

Waste Water TankThe 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.


Quotes

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 reduces, management of traffic is reduced to a minimum and there is less disruption to the local community, this is very important as it allows then 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.”

Jeff Forrester - ESD, Delivery Project Manager

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.


Quotes

The Lochaline WTW was awarded to EDS 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”

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

Paul Gerard – ESD – Design Lead & Process Engineer

Gavin Steel, Scottish Water’s Regional Communities Manager for the Highlands, said:

• Membrane Plant building including laboratory and welfare facilities • Membrane Filter Feed Pumps • Raw Water Feed Pumps• Strainers • Membrane Filtration Modules • Membrane Clean In Place (CIP) and Neutralisation facility • Permeate Tank • Membrane Filter Recirculation Pumps• Disinfection (Sodium Hypochlorite dosing and Chlorine Contact Pipe (CCP)) • pH Correction (Limestone Contact Tank) • Re-lift Pumps • Final Water Flow Monitoring • Water Quality Sampling for control and Regulatory purposes • Waste Water Tank • Motor Control Centres • Local Control Panels • Telemetry

Addition Site scope included:

• Dechlorination Chamber• Standby Generator• Septic Tank• Civil Groundworks & Drainage• TTU Building Foundations• Services• Clean Water Tank• Treated Water Pumping Station


Scope SummaryAn effective cryptosporidium barrier was installed at Lochaline WTW. To achieve this a Nanofiltration Membrane based process deployable output of up to 195m³/day. Also included are provision for Welfare Facilities, Membrane Feed and Recirculation Pumps, new Clear Water Tank (CWT-1) of capacity 146.3m³, Re-mineralisation Tank, Chlorine Contact Pipe, Dechlorination Chamber, Standby Generator, Site Control System, Telemetry and new domestic waste Septic Tank.

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