Designing for a OneBox® controlled smart low pressure sewer network in Europe
Residents in many rural areas in Ireland, like many other countries, rely on individual septic tank systems to provide treatment of wastewater. Gweedore is such an area located in a truly scenic area of County Donegal and characterised by dispersed development, along either side of a regional road. The surface geology of the area is dominated by blanket bog overlying shallow granite with protruding rock, and sands in the coastal area leading to a high water table. Not great territory for effective wastewater treatment with septic tanks, as was indicated by emerging water quality issues in the adjacent bay.
A commitment to deliver a sewerage system in Gweedore, Co Donegal was given as part of Water Services Investment program in 2013 predating the formation of Irish Water. Failure to address this and provide a collection system and associated treatment facility for Gweedore would have resulted in Ireland being prosecuted for non-compliance with Urban Wastewater Directive (UWWD).
Due to topography, ground conditions and the nature of the development, a conventional gravity collection system was impractical from an economic and technical perspective. Deep excavation in both rock and bog would present significant construction challenges and introduce a high level of programme and cost uncertainty. Maintaining pipeline integrity in these ground conditions is extremely difficult; and would pose risk of pipe settlement and water ingress with potential significant impact on ongoing operational costs. All of the above, in conjunction with the complex land ownership patterns in the area, would also have precluded the connection of many properties to the network.
As such a challenge was issued, to identify a practical and implementable solution that could resolve the issue and was economically viable.
“We want to provide the highest quality service to our customers. The low pressure sewer system will allow delivery of a comprehensive collection system in Gweedore that was simply not practicable using a conventional drainage solution.” Said Mark O’Callaghan, Business Lead – Innovation, Standards and Technology at Irish Water
A utility-to-utility conversation between Irish Water and South East Water, facilitated by Iota, highlighted details of South East Water’s PeninsulaEco (PenEco) project – globally the single biggest smart low pressure sewer scheme.
The benefits achieved by this project captured the interest of Irish Water’s executive team who saw it a novel way to meet the challenges of the Gweedore Scheme, whilst also having the potential to address:
- Servicing of dispersed properties on the periphery of existing networks;
- Where conventional networks are not considered viable; and,
- Providing a very effective system that could be deployed to service dispersed communities and properties.
“We have a culture within Iota – and more widely throughout our parent company, South East Water – to share learnings, insights and technology with our industry peers. Details of the PenEco pressure sewer system were highlighted and the alternative sewering method, along with the near real-time monitoring and control capabilities of OneBox® posed a potential solution to many of the challenges being faced by Irish Water.” said Eamon Casey, Technical Director at Iota.
“The proposed project in Gweedore hadn’t progressed any further than the feasibility stage at that point, due to the very difficult terrain and the prohibitive cost of a gravity sewer system. The option of a smart low pressure sewer, similar to the PenEco installation opened up an opportunity for us that we hadn’t investigated previously. We also saw the attractiveness of having a smart system that could be remotely controlled and managed.” Said Mark O’Callaghan, Business Lead – Innovation, Standards and Technology at Irish Water
Irish Water engaged Nicolas O’Dwyer (NOD) Consulting Engineers to provide design and project management services on its capital delivery program, which included the Gweedore sewerage system.
NOD engaged Iota to deliver the detailed hydraulic design of a smart pressure sewer scheme for the township of Gweedore consisting of approximately 700 individual connections.
“We saw the appeal of Iota’s smart pressure system, not only due to its simplicity and cost-effectiveness, but also because of cost estimates for a gravity sewer solution, that proved uneconomic due to the difficult ground conditions.” Stated John Flavin, Associate Director at Nicolas O’Dwyer
Iota designed the smart hydraulic sewer network, based on South East Water’s learnings from the PenEco project, which is monitored and controlled by OneBox®.
The proven benefits of a OneBox® controlled low pressure sewer network
The feasibility study confirmed the appropriateness of smart low pressure sewer for the project. Environment One Corporation (E/One), was awarded a tender to install and connect the initial 700 grinder pump units in Gweedore. Amongst the benefits recognised by Irish Water in deploying E/One’s pumps with Iota’s OneBox® control system were:
The capacity to identify and address issues before they impacted on the customer service; Infiltration alarms through monitoring of run time;
Controlled flushing of the network to prevent solids deposition; and
The ability to balance flows to treatment facilities
All of which have potential to impact favourably on both capital and operational costs, whilst assuring a quality service to Irish Water customers and good environmental outcomes.
“Irish Water wanted to maximise the functionality of the system. E/One’s industry-leading reliability and ruggedness coupled with OneBox® for command, control, and communication will drive extreme customer satisfaction and ensure success of the scheme. The E/One and Iota solution is set to deliver this.” Stated Derek Lachut, Director of Engineering at Environment One Corporation
The solution which provides remote monitoring and control of individual sites and the network as a whole will support Irish Water to provide a better customer experience; reduce operational expenditure by reducing the need for emergency on-site maintenance outside normal working hours; and avoid the risk of spills into the environment through near-real time alarms.
Irish Water expects to realise a reduction in the project capital expenditure due to an optimised network. It is designed to manage flows and utilise individual units across the network as additional storage capacity in high flow events, for example post power outages or storm events. This ultimately allows for smaller diameter pipes throughout the system.
“Further capital savings are realised through reduced construction costs due to shallow trenches or trenchless installations and no requirement for major pump stations.“ Continued Derek Lachut, Director of Engineering at Environment One Corporation
The Gweedore project has now commenced, with the first 42 homes and two commercial properties in the rollout due to be completed in the coming months.