--- title: "Feasibility Studies" description: "Ground, flood, drainage, water, access and structure checked before a site is bought or a design fixed, with abnormal costs named." updated: "2026-10-12" url: "https://www.petruf.ie/services/consulting-and-compliance/feasibility-studies" --- # Feasibility Studies > Ground, flood, drainage, water, access and structure checked before a site is bought or a design fixed, with abnormal costs named. A site is priced on the assumption that it can be founded, drained, serviced and reached at a normal cost. A feasibility study tests that assumption before the money is committed, and names the abnormals that would change the price. The architect tests what planning will allow on a site. The engineer tests whether it can be built, drained, accessed and serviced, and what that costs. Both answers are needed before a site is bought, and they are cheapest to get together. We specify the site investigation and read it, screen the flood risk, find the outfall, start the Uisce Éireann enquiry and check the access. For an existing building we check whether it can take an extra storey, a change of use or new openings. The result is a list of abnormals a quantity surveyor can price. ## What we check ### Ground A desk study of the GSI maps and nearby boreholes, then the site investigation it calls for, read for what it means for the foundations. ### Flood risk A Stage 1 screening against the OPW maps and the county SFRA, and a plain answer on whether a fuller assessment is needed. ### Drainage outfall Where surface water and foul can go, by gravity or pumped, and how much of the site attenuation will take. ### Water and wastewater capacity An Uisce Éireann pre connection enquiry started early, since the answer takes months. ### Access Sightlines, the junction onto the public road and swept paths, to DMURS or TII standards. ### Existing buildings Whether the walls, slabs and foundations can take an extra storey, a change of use or new openings. ### Structural options Frame type, grid, and precast or in situ, chosen while the layout can still follow. ### Abnormal costs Piling, made ground, pumping, retaining walls, network upgrades and diversions, listed for the quantity surveyor to price. ## What each check can turn up Each of these is a cost a normal price does not include. Found before the site is bought, it is a line in the negotiation; found after, it comes out of the margin. ### Ground: Made ground, soft alluvium or peat Piles or a raft instead of strip foundations, and the cost of disposing of what is dug out. ### Flood: Land in or beside Flood Zone A or B Raised floor levels, compensatory storage, or a use the site cannot take. ### Drainage: No gravity outfall within reach A pumping station, a long outfall, or more of the site given to attenuation. ### Water and wastewater: A network without the capacity Upgrades the development has to fund, and months added to the programme. ### Access: Sightlines the entrance cannot achieve Junction works, land from a neighbour, or a different entrance. ### Existing structure: Walls or foundations already at their limit Strengthening, new foundations, or a smaller scheme. ### Radon: A High Radon Area on the EPA map A radon barrier as well as the standby sump: a cost line rather than a reason to walk away. ## What you receive Each finding with what it means for the price and the programme. - A report on each check, with the risks ranked - A list of abnormal costs for the quantity surveyor to price, or for the land negotiation - The site investigation specification, and the results read for the foundations - The flood risk screening, and whether a fuller assessment is needed - The Uisce Éireann pre connection enquiry, submitted - For an existing building, what it can take and what would have to change - The surveys still needed, and the order to commission them in ## From our projects ### [Ardbrae Park](https://www.petruf.ie/projects/public-infrastructure/ardbrae-park) The Irish Water pre connection enquiries and diversion applications started alongside the drawings, because that correspondence is usually the long pole on a scheme this size. ### [Easra Court](https://www.petruf.ie/projects/residential/easra-court) Sixty seven apartments on 0.194 hectares: a site that tight settles the frame before anything else does. ## The questions that come first ### What does an engineering feasibility study include? The checks that decide whether a site can be built on at a normal cost: the ground, flood risk, the drainage outfall, water and wastewater capacity, access, and the structural options, with the abnormal costs each of them produces and what to do next. ### Should I get one before buying a site? Yes, wherever the sale allows the time. It shows whether the price assumes ground, drainage or access the site does not have, and an abnormal found before contracts is a line in the negotiation rather than a loss. ### How is it different from an architect's feasibility study? The architect tests what planning will allow: the massing, the density and the zoning. The engineer tests whether it can be founded, drained, reached and serviced, and what that costs. The two are best done together, because each changes the other. ### Do I need a site investigation at this stage? Not always. The desk study says whether one is needed and how much: sometimes the published ground information is enough to price the foundations, and sometimes two days of trial pits change the scheme. The report usually follows within a fortnight of the rig being on site. ### How long does a feasibility study take? The desk work takes weeks rather than months. What takes longer is outside anyone's control: a site investigation needs a contractor and a rig, and Uisce Éireann's answer to a pre connection enquiry averages about sixteen weeks, which is why that enquiry is made first. ### Can an existing building take an extra storey? Only a survey of the foundations, the walls and the stability system can say. Councils often ask for one with the planning application, and it is cheaper to know before the design is drawn around a storey the building cannot carry. ### Does a feasibility study commit me to the full design? No. It is a normal appointment on its own, priced on its own, and it does not commit you to anything that follows.