Try using it this way: Water first thing inthe morning and then spray the areas you want to kill. The Garrett juice may knock out the effect some but no matter what happens you are improving the soil so take heart.
Don't think you have made the gallon useless. You haven't. If the way you have mixed it negates its weed killing ability, dilute it heavily and then just use it as a liquid soil amendment. You are still in our alkaline soil area so it shouldn't have anything but a beneficial effect. I'd spray it in the evening only, however, and only on turf so you have less chance of burning anything.
It ain't lemonade but it's not useless, either.
Kathe