Plant Utilities worked example

Wastewater Surcharge Cost at 110% share of flow above surcharge threshold: a worked example

Push share of flow above surcharge threshold up to 110% and the picture changes. This example computes every intermediate figure at that operating point. Use it when reviewing wastewater surcharge cost for a utility budget, maintenance priority, capacity check, energy project, or production support plan.

The inputs for this scenario

  • Metered discharge volume: 650 kgal (unchanged)
  • Wastewater surcharge rate: 4.2 $ / kgal (unchanged)
  • Share of flow above surcharge threshold: 110 % (raised for this scenario; the documented default is 100)
  • Sampling and compliance adder: 300 $ (unchanged)

Working through the calculation

  • Applying the documented formula (Total wastewater surcharge cost = surcharge volume × wastewater surcharge rate × volume subject to surcharge + sampling and compliance adder) to the inputs above produces each figure below.
  • At this operating point the engine returns 3,303 $ for total wastewater surcharge cost, the number this scenario is built around.
  • At this operating point the engine returns 5.08 $ / item for cost per item or period.
  • At this operating point the engine returns 3,003 $ for variable wastewater surcharge cost.
  • At this operating point the engine returns 300 $ for fixed utility adder.

How this compares with the baseline

  • Against the tool's baseline example, where share of flow above surcharge threshold sits at 100% and the headline result is 3,030 $, this scenario comes in 9.01% above the baseline at 3,303 $.
  • It computes total monthly wastewater surcharge cost as surchargeable volume times the POTW surcharge rate plus a fixed sampling and compliance adder, and breaks out the variable and fixed pieces. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Total wastewater surcharge cost: 3,303 $ (headline result)
  • Cost per item or period: 5.08 $ / item
  • Variable wastewater surcharge cost: 3,003 $
  • Fixed utility adder: 300 $

Run it with your numbers

  • Every input above is editable in the live Wastewater Surcharge Cost calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.