You’ll want to rinse and scrub the clams from debris under cold running water. This will also give you a chance to check (and discard) clams that are cracked, feel hollow, or gaping open. All clams should be tightly closed. Soak the clams in a bowl of salt water - about 4 quarts cold water + 1/3 cup salt - for about 20 minutes to 1 hour. This will help filter out the sand and grit. Using a slotted spoon, drain the clams from the water and into a colander (pouring the water and clams together into a colander will add all that sand right back!), rinsing them thoroughly.