The city of Oakmont is interested in developing some lake front property into a sports park (picnic facilities, boat docks, swimming area, etc.). A consultant has estimated that the city would need to invest $3 million in this project. In return, the developed property would return $500,000 per year to the city through increased tax revenues and recreational benefits to the public. What would the life of this project need to be in order to be cost-beneficial to the city? The interest rate on municipal bonds is 6% per year.