Answer found on ways to calculate per gallon sewage treatment costs

A rough number for tertiary treatment is $5 per gallon of treated sewage, according to response.

Given the complexity of the operation that goes into treating raw sewage for a muncipality, it is not surprising that the question of how to calculate costs per person or per gallon of treated sewage is one that surfaces frequently.

Most recently, Tony Metzner posed such a question to members of the American Public Works Association newslist.

"Could you direct me to estimating guidelines for rough costs to construct a municipal treatment plan as it relates to population?" he asked. "I would also like to estimate infrastructure and operating costs."

Tim Faas, with the Western Townships Utility Authority in Michigan, provided an answer saying, "A rough number for a plant constructed with a tertiary level of treatment is $5 per gallon per day of treatment. We recently used this figure in estimating the cost for a 30 mgd plant in Michigan."

He added that "You can back into the per person number using 100-120 gallons per day per person, or what ever figure your area uses typically."

As far as operation and maintenance costs, Faas recommended that Metzner, or anyone else attempting to calculate such costs, refer to the Water Environment Federation Benchmarking Report (1997). It lists rates for various sized systems across the United States. For more information, go to WEF's website at www.wef.org.

Anyone with additional information to share may contact Public Works Online at mail:jeverhart@vertical.net or Metzner at AVMetzner@att.net.

Edited by Joyce Everhart
Managing Editor, Public Works Online