Nope 1.5 billion is paid by the feds, so 6.7 is paid by the GET surcharge.  But a third of that is paid by tourists so 4.5 billion is paid by taxpayers. 

This is  paid off over 15 years or a cost 0.3 billion a year. 

In 15 years we can expect an increase of about 200,000 in population. A rough estimate based on the number of housing units built over the last 7 to 10 year. Besides other Oahu  condos, the Hoopili and the Kia Ridge developments which have added about 20,000 units or 80,000 residents. Using an average of 1.1 million residents we get $250 a year per resident. 

This comes to $21 a month. If we spend half of the 3 billion contingency, or 1.5 billion that's an extra $5 a person using similar reasoning. Very much less than you figure.