Locating Subsurface Utilities Inside Buildings
Tenant improvements and renovations are a huge sector of the construction industry. Contractors regularly acquire a space and then require finding and tieing into the existing services below the slab. Depending on the age of the building as built plans can be limited or even non-existent! Even in brand new buildings things aren’t always what they seem..
At Geoscan we regularly utilize Xradar ™ Concrete scanning to scan slab on grade in order for clients to safely trench for installing new plumbing below the slab. However finding the existing utilities below before trenching is paramount.
No point trenching in the wrong place!
Geoscan has scanned numerous proposed trenches for clients only to find that the pipe they are trying to tie into,
- Isn’t where it’s supposed to be.
- Isn’t deep enough for them to make the grade
- There is a conflicting utility or footing in their path to it.
In some situations clients have proposed trench lines for washrooms that tie into storm drains!
Therefore it is much better practice to know the existing layout of all the utilities then plan the floor trenching from that.
Sub-Slab Utility Plan
We combine Xradar ™ concrete scanning with our low frequency GPR (ground penetrating radar) and EM (electromagnetic) utility locating methods to identify the layout and route of all the utilities below the slab. We can then digitally overlay our findings on an existing floor plan, on site!
Using this, clients can plan and layout their trenches, avoid conflicts and then most importantly safely cut the slab to tie into them all in one service!
- Saving Cost and headaches!
-Perhaps there is a much shorter route for your line saving cutting costs.
-You certainly shouldn’t and don’t want to be cutting through footings or thickenings.
-Avoid embedded conduits as well as pipes and conduits below the slab when cutting and trenching.
– Avoid splitting rebar lengthways while cutting, this greatly improves cutting efficiency and cost.
Q – Why not only do a utility locate?
A – Utility locating GPRs operate at low frequencies meaning they can penetrate quite deep however the resolution is poorer. You are unable to accurately mark out rebar and embedded conduits in the slab using a utility GPR. A high frequency concrete scanner provides a much better resolution at shallow depths for finding things in the slab or just below. Combining the two gives you the best of both worlds.
Q- Why is it useful to locate the plumbing below the slab? If I have scanned and cleared the slab for cutting?
A- Often where you’re told the sanitary line is, isn’t always correct. People mistake storm drains for sanitary drains. People cut their trench only to realise there is a waterline or electrical in the way of their proposed sanitary line. Similarly the depth of the sanitary line where they had proposed to tie in isn’t enough for them to make the grade. Often the full route of the line isn’t known meaning there may be a much shorter route you can take to tie into saving you cutting that big trench across the room when you don’t need to.
Q – Does it cost extra to produce the sub-slab utility plan?
A- There is no specific extra cost for the utility plan sketch, it just adds a small bit of site time as we complete it onsite and include it in our report which we send upon leaving.
Q- Can you Locate footings?
A –If the footing is flush with the bottom of the slab then yes! If it isn’t it IS still possible just a little tricker.
Q – Is this a CAD drawing of the interior utilities?
A- This isn’t, but we can! We can produce a CAD drawing of the Utility Layout as well as 3D walkthrough that is priced separately. See this link for example (insert link here)