Would pouring baking soda into my sand mound drainfield be helpful to remove buildup in the pipes?

I ume you are talking about your septic drainfield. No, nothing but water should be going into your drain field. Your septic tank should be capturing any solid waste and releasing only water that should be entering your drain field. I don't think baking soda is good for septic systems. baking soda kills germs and germs help break down waste in your septic.If a drainfield clogs up it must be rebuilt or replaced.