This is just an idea I've been kicking around lately for my next system, a lot of people bury IBCs or other tanks for a sump which takes up space. I was thinking if you're building raised beds you could just put 55 gallon barrels on their sides under your GBs and link them together, burying 2" pipe as needed to tie them all together as your "distributed" sump using space that would be wasted anyway.
Benefits would be:
1. Less wasted floorspace / recovering space that would be wasted under the GBs.
2. Pump with less head rating can be used versus a buried IBC = electricity $$$ savings (probably not a lot though) or better for solar?
3. Just burying some pipe a few inches deep if needed versus digging a giant hole for IBC
Of course as with anything there are a couple of potential issues:
1. Probably would want to add lattice or skirting on the GBs to keep the barrels from being knocked around potentially causing leaks.
2. Would want a pump pulling water from and/or GB draining in to each barrel to avoid stagnant zones.
3. Depending on your local market, potential cost of multiple barrels vs an IBC.