Please tell me what these "whole heap of other factors" are ?
Here's a few for starters:
1. Gross retail area, which obviously has a significant bearing on takings. The Hibbert lane is likely to have more net space, and therefore a higher projected turnover.
2. Access and construction issues. Hibbert Lane is a level site and should be easy (and therefore cheap) to build on - plenty of space for plant and site cabins, easy access for lorries. Chadwick/Trinity Street is on a slope and is a more constricted site - less room for access, cabins, tower crane etc. Therefore likely to be a more costly build.
3. Hibbert Lane will have a fuel forecourt, unlike Chadwick Street. Therefore significantly more revenue.
4. Geology/decontamination. Chadwick Street may have an industrial past (I don't know, just guessing), which may mean decontamination costs.
So Chadwick Street may be a more economic option for Asda than Hibbert Lane - or it may not. Without detailed and expert analysis, we really can't know.
Meanwhile, this is very interesting:
ASDA have undertaken to do the College refurbishment themselves or at least with their own contractors
What's your source for that, Simone?