In a very large bowl, combine the cucumbers, chiles, garlic, horseradish, onion, dill, mustard seeds, coriander seeds, peppercorns, bay leaves, and grape leaves. Pack this mixture into a wide-mouth gallon crock or jar.
In a separate large, nonreactive bowl or pitcher, combine 12 cups water, vinegar, and salt to make the brine, stirring until the salt dissolves.
Cover the cucumber mixture with a plate, then weight the plate down with a clean stone, a brick, or whatever you have available; the idea is to keep the cucumbers submerged as they pickle. Add enough of the brine to cover the cucumbers by 2 inches or more.
Cover with a clean cloth, and store at room temperature for 4 to 7 days, taking care to keep the contents submerged at all times and to skim any foam that may form on the brine's surface every 1 to 2 days.
The pickles are done when their pale-green color is mostly the same inside and out. They will keep, covered and refrigerated, for 1 month, but they will start to soften unless you've included plenty of grape, cherry, or oak leaves. To freshen the flavor of the brine, you can strain the solids out of the liquid, bring the brine to a boil, cool it to room temperature, and re-immerse the cucumbers and other vegetables in it, discarding the original flavorings and freshening the flavor with more of those same flavorings.
They will keep, covered and refrigerated, for 1 month.