Surveys of the Project Area
A number of surveys will take place from January 2020 as part of the preparatory work prior to construction of the GDD project.
The surveys will be taking place at the wastewater treatment plant site at Clonshaugh, at the Abbotstown pumping station site, and along the routes for the new orbital sewer and the outfall pipeline (land-based sections).
Conducting these surveys is necessary to ensure that as much information as possible is known about ground conditions within the project area in advance of the main construction. These surveys will provide valuable data to enable the construction phase to run smoothly and minimise the risk of potential delays.
Types of Surveys
The surveys include ground investigations comprising boreholes, trial pits, and slit trenches. Causeway Geotech will be carrying out the survey works on behalf of Uisce Éireann.
Boreholes:
Boreholes are used to assess the composition of rocks below our feet, using similar equipment as show below. One borehole takes two to three non-consecutive days to complete, as two different sets of machinery are required. Along the entire route of the project, 70 boreholes will be carried out. After each borehole is completed, the area will be reinstated.
Trial Pits:
Trial pits are used to assess the composition of soil below our feet. Each trial pit will take 1-1.5 hours to complete and the site will be reinstated following each investigation.
Slit Trenches:
Slit trenches are used to confirm the location of underground utilities. The slit trenches are primarily conducted alongside public roads. One slit trench takes, on average, half a day to complete.
Geophysical Surveys:
Geophysical surveys are a non-invasive means of characterising the soil and rocks far below the surface of the earth. To carry out these surveys an instrument trolley is pushed slowly across the area and measurements recorded. The trolley used is smaller than an average shopping trolley and takes one day to cover approximately 150 metres.
Where are the surveys taking place?
Surveys are planned to take place along the route of the orbital sewer pipeline, at the Abbotstown pumping, station location, at the wastewater treatment plant site location at Clonshaugh and on the land side route of the outfall pipeline. The surveys will commence at Abbotstown moving eastwards. Landowners will be contacted in advance of the surveys if their lands are affected.
What are the working hours?
Survey work will begin in early January and will only be operational 08:30hrs to 17:00hrs, Monday to Friday. As the daylight lengthens, the working hours will increase to a maximum of 08:00hrs-18:00hrs. Work affecting roads will be conducted during off-peak hours (i.e. outside of 07:00hrs-10:00hrs and 16:00hrs-19:00hrs).
When will the surveys be complete?
The ground investigation surveys will commence from mid-January 2020 and will be completed by end April 2020.