I used to work for a company that mainly designed refinery units, specializing in the heavy oil end but also did complete refineries for places like Brazil and other countries.
The cost of adding 250 MBPD to an existing refinery of the same size was about 40% the total cost of building a 250 MBPD refinery on a completely empty location. The infrastructure to support the increased output is so much cheaper than building it from scratch.
Roger that. I worked at KSC and we constantly had to mod and upgrade the LOX and LH2 storage/supply facilities. Sure beat the cost of building new ones. Especially the dewars for storage. Saturn program era builds. But they worked.