Aeration Basins for Chlorine Contact Tanks

Has anyone heard of WW packaged plants (1.5 MGD) utilizing a portion of its existing aeration basins (with course bubble diffusers) as chlorine contact tanks? It appears that the aeration system is used for mixing to achieve a 1.0 Baffling Factor in lieu of actual intra-basin baffles. We are in the process of re-locating a wastewater packaged plant and need to construct temporary chlorination contact basins/tanks for 20 minute Ct, while the permanent chlorine tanks are re-built, and would like to use as much existing equipment possible. Any input on designing chlorine contact tanks (from scratch) in general would be appreciated. We also have the option of using 8.5' wide x 42' long x 9' tall frac tanks, but of course these would require significant baffling to get a 20:1 length-to-width ratio to prevent having to use a 0.3 Baffling Factor. It appears that to use the 1.0 baffling factor there must be a "very high length to width ratio, perforated inlet, outlet, and intra-basin baffling" used. The design flow rate is 1.5 MGD, and peak flow is 6.0 MGD.

Thanks