Please show us for the whole document attach to the contract as I know the used coolant water was not mentioned in the contract (I remember that the last time, we made contract for water contaminated with oil; not for used coolant water). I cannot found any problem if we utilize service from other company and I also cannot find we promise them to provide the used coolant water for them to disposal (the volume of used coolant water).
For Siam material Company, now, Ministry of Industry already approved them to be the used coolant water disposer.
I do not know what is your problem now, why you cannot negotiate the price from Siam Material Company and use the service from them for used coolant disposal as soon as possible.
Note: the type of disposal of used coolant water (burning or recycle) for FCM, has no problem if Thai government is accept and approve.
Please do the best way for our company, now, we would like to get more and more for cost saving.