I'm guessing it's plumbing, not conduit. Unless you actually see wires running through the tubing, I'm not convinced it's conduit. In the US only certain types of conduit are listed for use, and I'm sure they are similar in Canada. Copper is not among those listed, so it's not likely it would be approved by an inspector.
In a comment you mentioned that the pipe was connected using "nuts", and therefore could not be used for water. However, I disagree. A union is a fairly common fitting in plumbing. In fact, you'll probably find some if you look at the plumbing for the water heater in your house.
Update:
After further searching National Electrical Code, I found this...
National Electrical Code 2014
Article 344 Rigid Metal Conduit: Type RMC
II. Installation
344.10 Uses Permitted.
(A) Atmospheric Conditions and Occupancies.
(2) Red Brass RMC. Red brass RMC shall be permitted to
be installed for direct burial and swimming pool applications.
(B) Corrosive Environments.
(1) Galvanized Steel, Stainless Steel, and Red Brass
RMC, Elbows, Couplings, and Fittings. Galvanized steel,
stainless steel, and red brass RMC elbows, couplings, and
fittings shall be permitted to be installed in concrete, in
direct contact with the earth, or in areas subject to severe
corrosive influences where protected by corrosion protection
and judged suitable for the condition.
(C) Cinder Fill. Galvanized steel, stainless steel, and red
brass RMC shall be permitted to be installed in or under
cinder fill where subject to permanent moisture where protected
on all sides by a layer of noncinder concrete not less
than 50 mm (2 in.) thick; where the conduit is not less than
450 mm (18 in.) under the fill; or where protected by corrosion
protection and judged suitable for the condition.
Which means it's possible the conduit is not copper, but red brass. According to wikipedia, red brass may be 85% copper, 5% tin, 5% lead, and 5% zinc.
I don't know what regulations allow, but I have never seen horizontal boring done without installing the HDPE flex conduit as part of the process.
They bore by pushing the bit forward until they hit the destination. Then they swap the boring bit for a pulling end, and pull the conduit back through the hole as they are removing the drill rod. There is no separate conduit installation from the boring; you can't realistically push conduit through the bored dirt afterward.
How are you planning on doing the boring? Is this something you are going to jerry-rig yourself, or hire a company to do? If you are hiring it out, they likely will have some leftover end spool. As you say, 30 feet is a small fraction of the 2000ft spool. It should not be hard to get that as leftovers from the boring company, I would think.
And if you are doing it yourself, perhaps you can still buy some end spool offcuts from a boring company.
Best Answer
The big home improvement stores have elaborate systems in place to determine what sells in each store and figure out what products will bring the best return with the finite space they have for inventory.
There are lots of products that are very good or necessary that won't get a spot just because they are slow sellers. Other retailers / wholesalers / distributors are set up to inventory more variety in specific categories. So a local electrical supply will have things that are not as big of a seller.