One of the key components in our evaluation of treatment technologies is the long term O&M cost to operate and maintain the system. We have found that in some cases the O&M savings for utilizing a technology when evaluated over a 20 year period and evaluated on a Net Present Value Basis (NPV) can equal the cost of the system.

The following is an example to demonstrate the importance of O&M cost.

Treatment System
Technology A
Technology B

Initial Capital Cost
$1.2 mm
$900k

20 Year O&M NPV
$800k
$1.9 mm

Total Cost
$2.0 mm
$2.8 mm

If you were just comparing the initial capital cost, you might select Technology B, as it is $300k lower in capital cost. But when you look at the 20 year NPV, Technology A is $1.1mm less expensive than Technology B. Overall Technology A is $800k less than Technology B.

This example is not uncommon when evaluating onsite technologies so it pays to ask for a detailed analysis from your design-builder before selecting a treatment technology.