Based on your conditions, here's what I would recommend doing:
1. Add baking soda for a TA target of 70
2. At the same time, add enough liquid chlorine to get the FC to 10 ppm. Re-test in 10 min. If it remained at 5 or above, go to next step. If not, repeat by adding chlorine to an FC of 10 and test again in 10 min until you are sure the FC is starting to hold between 5-10 ppm.
3. Now that is holding FC between 5-10 for at least 10 minutes, add granular stabilizer via the sock method with a CYA target of 30.
4. Lower the pH to 7.2
5. Increase the FC to "12", maintain as best as you can, and follow the
SLAM Process.
Be prepared to have lots of liquid chlorine available. One final thought - If the water is really bad, coupled with high chlorine prices, some people might elect to do a healthy water exchange if the cost of water is less expensive. It might also help accelerate the SLAM. Totally your call, but if you do exchange water, follow-up here with a new set of water test results and I'm sure that can change things.