Default unit cost estimates are provided for each state and the Chesapeake Bay Watershed. The Chesapeake Bay Watershed is an average of all states. Costs are provided as a starting point to use for creating your own cost estimates of various BMP scenarios. Costs are estimated in 2010 dollars. Capital and opportunity costs are amortized over the BMP lifespan and added to annual operations and maintenance (O&M) costs for a total annualized cost.
Costs are annualized average costs per unit of BMP (e.g.: $/acre treated/year). The formula is:
- annual costs = (capital * annualization factor) + O&M costs + (land * annualization rate)
- annualization factor = i/((1+i)^n - 1) + i
- i = annualization rate, which is always 5%
- n = period of annualization (also called lifespan)