Daldowie Integrated Drainage Plan
The Daldowie Integrated Drainage Plan forms part of the Glasgow Strategic Study project to deliver a drainage plan for the Metropolitan Glasgow Strategic Drainage Partnership. The original brief covered the need for investment to address aesthetic failings in sixUIDs which discharge intermittently within the Glasgow Daldowie WwTW catchment. These assets were promoted for improvement as additional requirements of the mainUIDassessment programme within the Greater Glasgow area. Furthermore and additional six confirmed areas of internal and external flooding caused by the local sewerage system had been identified and had been promoted for improvement.
The purpose of the commission was to provide sufficient information and deliverables to take the outline solution for each of the six UIDs and flooding locations, which were identified as part of the Glasgow Strategic Studies (GSS), through to capital investment approval. Our role as drainage area planning engineers and hydraulic modellers was to develop solution options to flooding and aesthetic river pollution issues across the catchment. The scope of services we provided were as listed below;
- Review of existing data, needs report, catchment solutions report and indicative solutions
- Manage data collection by survey contractors.
- Confirm suitability of indicative solutions and where not suitable, propose alternatives
- Provide all the required deliverables required prior to Feasibility Review
- Attendance at Feasibility Review
- Liaison with Scottish Water Asset Planner and Operations
- Confirm that the solution is hydraulically robust using computer modelling
- Increase confidence in the model where necessary by site survey
- Prepare and submit estimating proformas to Scottish Water Estimating team
- Support Scottish Water’s Shared Services team
- Project progress reporting to Scottish Water
- Liaison with construction management team during the build stage
The Daldowie catchment is located to the east of central Glasgow and includes all areas that drain to the Daldowie, Hareshaw and Coursington WwTWs. Within the catchment there are three wastewater treatment works, 31 pumping stations, 185 intermittent discharges. There are a number of watercourses that run through the catchment. The larger of these are the River Clyde, North Calder Water and South Calder Water. Investigations as part of the overall GSS planning showed that strategic intervention was required to address the flooding and river pollution issues in the catchment.
Catchment needs that could feasibly be solved in an integrated manner were clustered into Work Packages. This was based on their proximity to each other and the hydraulics of the drainage system. There were six river pollution drivers and 11 flooding cluster drivers to be addressed.
The Craigneuk sub-project involved a complex interaction of 6 flooding clusters. The discrete solutions we developed resolved flooding close to their reported (and model predicted) locations but each solution also impacted on the solution downstream. We used a strategic combination of discrete solutions, comprising a combination of online upsizing, catchment transfer and storage to resolve the flooding issues for the design criteria of 1 in 20 (external flooding) or 1 in 30 (internal flooding) year return.
Some of the indicative solutions developed as part of the earlier ‘high level’ work proved to be impractical to construct when assessed in detail as part of our work. For example in Coatbridge an element of catchment transfer had been proposed, however this involved crossing a road bridge, which appeared fine in the model but on site the proposed pipe would have blocked the canal beneath.
The original brief was extended multiple times. What started off as a 6 month project evolved into a 3 year project as the client was very happy with our performance. As well as working to our own internal QA procedures our work was regularly audited internally at Scottish Water and at specific stages was externally peer reviewed to ensure compliance with current best practice.
Our involvement in the process extended to construction stage. We worked closely with the detailed design team and the site agent. Occasionally the construction team would propose a change to the design for practical reasons and we would model and optimise the change and feed the revised specification back to the site. These alternative scenarios demanded a fast turnaround as any delay to construction carried a heavy cost implication.