Environmental Science and Engineering

Performance and Costs for Decentralized Unit Processes

Publication Date: November 2010
Cooperating Institution: University of Tennessee
Principal Investigator: John Buchanan
Project Budget: $180,089
Project Identifier: DEC2R08


Small community leaders and planners have a critical need for information and tools to help make good decisions concerning local wastewater management. Community leaders and planners can use the resources from this project to help evaluate the performance, cost, and other factors of various technologies and decide which are the most appropriate for their particular needs.

This project includes a several interconnected products. The products consist of three components: a primer on wastewater basics; a series of fact sheets on decentralized wastewater collection, treatment and dispersal; and a decentralized wastewater cost estimation tool and accompanying user’s guide.

The primer, Wastewater Basics for Small Community Leaders and Planners, is the best place for users to get started. This document provides an overview of and context for the fact sheets and cost tool that were developed as part of this project.

A series of nineteen fact sheets give basic information on the full range of currently available collection, treatment and dispersal technologies for wastewater management and how they may be used individually or in combination. The fact sheets include the following:

Collection Fact Sheets
C1: Gravity Sewer Systems
C2: Pressure Sewer Systems
C3: Effluent Sewer Systems
C4: Vacuum sewer Systems

Treatment Fact Sheets
T1: Liquid-Solid Separation
T2: Suspended Growth Aerobic Treatment
T3: Fixed Growth Aerobic Treatment
T4: Constructed Wetland Systems
T5: Lagoons
T6: Nutrient Reduction
T7: Disinfection
T8: Residuals Management

Dispersal Fact Sheets
D1: Gravity Distribution
D2: Low Pressure Distribution
D3: Drip Distribution
D4: Spray Distribution
D5: Evapotranspiration System
D6: Surface Water Discharge
D7: Wastewater Reuse

A spreadsheet tool provides planning level cost estimations of different decentralized wastewater management scenarios commonly used in small communities. Initial capital costs as well as long-term maintenance and energy costs are included. Users can take advantage of the default unit cost values provided based on national data or use better, local information when available. A Wastewater Planning Model User’s Guide accompanies the cost spreadsheet tool.

The information from this project is not intended for detailed design, but rather to provide small community decision-makers the information necessary to work with engineers, soils professionals, construction managers and financial personnel to get the best wastewater solution for their community.

All of the products are available for download from a specially designed project website: www.werf.org/decentralizedcost. Alternatively, users can download the final compendium report which contains all the products in one document with the exception of the spreadsheet cost tool, which can only be downloaded from the website.

Associated Documents:
Project Website
Final Report