Irish Water Drainage Area Plan (DAP)

Provision of hydraulic wastewater models to support the delivery of Irish Water's Drainage Area Plan (DAP) Modelling and Surveying Framework


Irish Water is creating a library of hydraulic wastewater models under its programme of Drainage Area Plans, with the town of Portlaoise being prioritised after key drivers within the catchment were identified. These include hydraulic capacity of the network and WwTW; environmental compliance; operational and source control issues; and the town’s importance as a national transport node and the rate of population growth expected in the future. The investigation of these drivers resulted in the need for wastewater network performance assessments to be undertaken.



RPS delivered the Portlaoise Drainage Area Plan for Irish Water. This was one of the first projects delivered under their DAP modelling and surveying framework.  As part of the study, our team delivered all three stages of the DAP: Stage 1 (Data Collection and Scoping); Stage 2 (Survey Management, Model Build & Verification); and Stage 3 (Risk Assessment).



The project deliverables will be used by Irish Water to determine and prioritise risk associated with the urban drainage network, with a focus on wastewater and its impact on waterbody quality and the environment. The risks will determine current and future development scenarios and subsequently allow Irish Water to develop strategies and focus investment to serve this rapidly expanding town in a sustainable way.

The work has been well received by numerous stakeholders including Irish Water and the Local Authority (Laois County Council), with further follow up work being undertaken. Here our team of modellers and engineers utilised the DAP model to develop future system upgrade proposals to cater for catchment development growth while mitigating those risks previously identified.

"The outputs from Portlaoise DAP form the basis of some of IW’s Capital Investment Plans and are key to identifying the interventions required to address project drivers such as flooding, environmental compliance and catchment growth.  The DAP deliverables provide IW with the tools and data to support decision making in wastewater network asset management, helping IW to deliver improvements where they are most needed.  

Throughout the delivery of the DAP, the RPS team were hardworking, professional, and accommodating to our needs, at the same time meeting the requirements of IWs DAP standards and specifications."

Irish Water

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