CASE STUDY WHALSAY TTU

THE MODULAR

WATER EXPERTS TREATMENT

Project Title: Whalsay WTW – Nanofi ltration Membrane Plant Project Manager: Jon O’Neill Client: Scottish Water Project Value: £4.3M Design Start: 5th October 2015 Manufacture Start: 27th May 2016 Delivery to Site: 13th October 2016 Commissioned / WIS: 30th March 2017 Works Address: 2 Bothies, BU Water , Whalsay, Isle

www.ross-eng.com Case Study / Whalsay TTU

Project Overview:

Construction of the new multi-million pound Water The project uses Nanofi ltration (NF) and Reverse Osmosis (RO) technology Treatment Works in the Eastern Shetland Island of to ensure customers on the island can Whalsay was delivered ahead of time and within continue to enjoy fresh, clean drinking water long into the future with this budget by Ross-Shire Engineering’s, Water Technology new treatment process. The works department. incorporate a new intake from Loch and associated raw water pump station (RWPS) and raw water main (circa 700m), 452m3/d NF modular membrane plant with reverse osmosis process, operating at a combined recovery of 90% on the Whalsay site.

The Transportable Treatment Unit (TTU) was constructed in Ross-Shire’s workshop. The footprint of the modules were increased to 18m × 4.1m to give the operators more clear access around the equipment, whilst still ensuring that they were suitable for road transportation. The six modules were shipped to Symbister and delivered onto site on the banks of Loch Whalsay WTW Huxter, in October 2016.

Fig 1 - Works location map

Whalsay - Site before the new works were carried out Case Study / Whalsay TTU

Project Overview:

Whalsay WTW - TTU Floor plan

Whalsay WTW – 3D model Case Study / Whalsay TTU

Water Quality Tables

Raw Water Quality Envelope (Loch Huxter) April 2014 – January 2015

Parameter Units Min. Max. Mean 95%ile Mean + 2SD Count

Alkalinity mgHCO3/l 9.0 17.0 11.2 13.5 14.2 38

Chloride mgCl/l 73.0 102.0 89.8 100.0 103.2 40

Colour Deg Hazen 32.0 104.0 68.3 96.2 103.9 39

Conductivity µS/cm at 20°C 266 337 308 334 352 40

Hydrogen ion pH value 6.6 7.3 6.9 7.2 7.3 39

Suspended solids mg/l 3.0 6.0 3.2 4.1 4.3 40

Total organic carbon (fi ltered) mgC/l 6.5 11.8 9.2 11.6 12.6 34

Total organic carbon mgC/l 7.3 13.1 9.8 12.7 13.4 38

Turbidity NTU 0.4 2.0 0.7 1.4 1.3 40

Bromate µgBrO3/l 1.3 1.4 1.3 1.3 1.4 15

Bromide µg/l 209.4 369 265 305 332 35

Aluminium µgAl/l 32.0 114.0 63.3 99.1 103.5 38

Dissolved Aluminium µgAl/l 25.0 87.0 49.5 71.6 81.2 34

Dissolved Iron µgFe/l 66.0 241.0 131.4 195.4 216.3 37

Dissolved Manganese µgMn/l 1.6 58.0 6.5 23.0 27.5 36

Iron µgFe/l 102.0 408.0 196.5 314.1 338.9 38

Manganese µgMn/l 12.0 73.0 27.6 55.3 54.9 35

Total hardness mgCa/l 12.7 17.8 15.9 17.4 18.6 36 Case Study / Whalsay TTU

Water Quality Tables

Raw Water Quality Envelope (Bu Water; alternative emergency raw water source) April 2014 – January 2015

Parameter Units Min. Max. Mean 95%ile Mean + 2SD Count

Alkalinity mgHCO3/l 4.0 13.0 5.5 8.1 8.7 40

Chloride mgCl/l 72.0 100.0 84.1 98.1 99.1 40

Colour Deg Hazen 38.0 165.0 118.9 150.9 170.8 43

Conductivity µS/cm at 20°C 243 343 283 311 327 40

Hydrogen ion pH value 5.6 7.0 6.2 6.8 6.8 41

Suspended solids mg/l 3.0 6.0 3.2 4.2 4.3 38

Total organic carbon (fi ltered) mgC/l 6.1 18.9 12.7 17.4 18.7 38

Total organic carbon mgC/l 8.6 21.4 14.1 19.1 20.2 42

Turbidity NTU 0.7 3.3 1.5 2.2 2.4 42

Bromate µgBrO3/l 1.3 1.4 1.3 1.3 1.3 20

Bromide µg/l 60.1 412.9 237.1 282.4 347.1 36

Aluminium µgAl/l 61.0 315.0 235.1 286.9 318.0 42

Dissolved Aluminium µgAl/l 55.0 264.0 207.0 237.3 276.1 38

Dissolved Iron µgFe/l 148.0 383.0 306.1 368.3 391.0 38

Dissolved Manganese µgMn/l 6.0 26.0 14.7 20.0 23.7 35

Iron µgFe/l 174.0 500.0 358.9 414.0 458.6 41

Manganese µgMn/l 11.0 37.0 17.5 25.0 28.7 41

Total hardness mgCa/l 11.3 19.0 14.0 15.8 17.0 38 Case Study / Whalsay TTU

Water to Supply – Water Quality Targets

Parameter Unit RSE Target The Public Water Supplies The Water Supply () (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

Treated Water – Performance Test Results

Parameter Unit Minimum Maximum Mean 95th Percentile Count

Colour Deg Hazen <2 <2 <2 <2 29

Hydrogen ion pH value 8.1 9.5 8.7 9.2 29

Total organic carbon mg C/l 0.2 0.8 0.3 0.7 28

Turbidity NTU <0.2 <0.2 <0.2 <0.2 29

THM: Total mg/l <3.2 <3.2 <3.2 <3.2 22

Aluminium µgAl/l <9 17 11.1 14.8 29

Iron µgFe/l <7 <7 <7 <7 29

Manganese µgMn/l 1.5 1.5 1.5 1.5 29

Coliform bacteria cfu/100 ml 0 0 0 0 29

E. coli cfu/100 ml 0 0 0 0 29 Case Study / Whalsay TTU

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

The Nanofiltration (NF) membrane stacks, of which there are two, each consist of 56no. size C10 membrane modules with CA202 fi lter tubes, which have their primary inlet and outlets piped in parallel. Case Study / Whalsay TTU

Reverse Osmosis (RO) Modules Nanofi ltration (NF) Permeate passes into the Reverse Osmosis (RO) section of the treatment works. The fi rst RO stage is made up of two RO Stages operating in parallel. The RO Stage 1 Permeate is passed forward to the RO Permeate Tank. The RO Reject from stage one is then passed to a second stage of RO fi ltration. The Permeate from this second stage is also passed forward to the RO Permeate Tank. The Reject from the second stage of RO fi ltration is passed out of the building into the Burn.

Chlorine Contact Pipe (CCP) The Chlorinated Water flows through the CCP to ensure that there is the required contact time for disinfection. Incorporating the 23.9m, 500mm, CCP within the modular construction has reduced the amount of civils work on site, reducing time and work on site. Case Study / Whalsay TTU

Waste Water Tank The 30,000 litre 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.

Carbon Dioxide (CO ) Dosing Due to the nature of the existing mains distribution network a need was identified to alter the pH correction process to provide a greater degree of re- mineralisation of the Disinfected water. To achieve this CO is automatically dosed post the Limestone Contact Tank. Control is based on pH value.

Limestone Contact Tank The Disinfected Water feed fl ows up through the Limestone Bed within the Limestone Contact Tank to correct the pH and re-mineralise the water. If the Carbon Dioxide dosing is disabled, the pH control is achieved by an actuated blend valve which allows a proportion of the Permeate to bypass the limestone and blend the outlet pH to within acceptable levels. Trimming the amount of Permeate that is bypassed corrects the pH level. Case Study / Whalsay TTU

Client Commendation

Whalsay WTW – Site on completion

David Kitching, Senior Project Manager with Scottish Water, said:

“Scottish Water is pleased to announce construction works have now been completed to the new water treatment works in Whalsay”.

“The works have progressed as programmed and completion secured due to the off-site fabrication and commissioning of the modular membrane plant, reducing the site construction period signifi cantly, compared to contemporary construction.

“Final commissioning of the plant is complete and the plant started supplying water in late May 2017” “Customers will benefi t from fresher, cleaner water from the state of the art membrane treatment and reverse osmosis process, which provides advanced fi ltration and allows for a more effi cient treatment process.” Case Study / Whalsay TTU

Scope Summary

The works incorporate a new intake from Loch Huxter and associated raw water pump station (RWPS) and raw water main (circa 700m), 452m/d nanofi ltration modular membrane plant with reverse osmosis process, welfare facilities and standby generator.

The plant includes

• Membrane Plant building including welfare facilities

• Raw Water Tank

• Nanofi ltration Membrane Filter Feed Pumps, Strainers, Membrane Filtration Modules, Membrane Clean In Place (CIP) and Neutralisation facility and a Permeate Tank.

• Reverse Osmosis Feed Pumps, Membrane Filtration Modules, Membrane Clean In Place (CIP) and Neutralisation facility, Permeate Tank and Permeate Pumps.

• Disinfection (Sodium Hypochlorite dosing and Chlorine Contact Pipe (CCP))

• pH Correction (Carbon Dioxide Dosing and / or Limestone Contact Tank)

• Relift Pumps

• Final Water Flow Monitoring

• Water Quality Sampling for control and Regulatory purposes

• Chemical Waste Tank

• Motor Control Centres

• Local Control Panels

• Telemetry