Deposit Control Additive (DCA) injection, at Terminal tanks or Trucks loading racks?

A more intricate injection system might be more expensive initially, but it's a one time expense, as opposed to a continual loss of product in perpetuity...so the breakeven point should be determined, or estimated, and justification can be presented....or not..

https://360.lubrizol.com/2019/Deposit-Control-Additives-Play-a-Critical-Role-in-Todays-Fuels

If you have a complex distribution system with multiple injection points, it is inherently less reliable, and provides no recovery in the event of failure during export loading. If your primary injection system fails, you have the option of adding it before shipping it out. You can perhaps evaluate the costs of shipping out unconditioned fuel vs. the cost of a failsafe injection system with flow checks on main & additive and production interruption in the case of instrument and additive equipment malfunction.

The value of the additive once dispersed should be evaluated, if you are considering the cost of lost additive with lost fuel. I have to believe that the cost of the fuel discarded is far more than the cost of the additive once diluted, so the argument to dose upon shipment seems contrived.

Polyisobutylene can be bought for $2.20 per kilogram, and, I'm guessing that other DCAs are similar: so if your worried about losses due to tank cleaning then I think you should be more concerned about loss of fuel.

I think that depends on how water soluble the additives are...

https://www.emersonautomationexperts.com/2022/measurement-instrumentation/flow/automating-tank-dewatering-operations/

The best thing to do is to bounce it back up to the Design Office, and ask there - just in case someone there scowls at the initiative and the commercial consequences of having been taken as an outcome of asking a bunch of anonymous strangers on the internet.

Surely there is/are (a) drawing(s)?