Recycling Treated Municipal Wastewater for Industrial Water Use

Introduction
Appendix B
Reclaimed Water Transmission Main Capital Cost and Pumping Cost Analysis
This technical memorandum presents the assumptions, methods, and results of a
transmission main capital cost and power cost analysis of a general water reuse system.
Piping Capital Cost
It is assumed that all reclaimed water transmission pipes will be force mains for this master
planning level of analysis. Typically, pipe materials for reclaimed water mains are polyvinyl
chloride pipe (PVC) , specified as DR 18, Class 150, meeting AWWA Specifications C-900
and C-905 with push-on joints, or ductile iron pipe (DIP), Class 51, with push-on joints and
cement lining on the inside and a bituminous coating (16 mils DFT) on the outside. For the
purposes of this analysis, it is assumed that all mains 24 inch or less in diameter will be PVC,
DR 18, Class 150; and for pipe larger than 24 inch, DIP class 51.
A pressure of 40 pound per square inch (psi) at the end of the transmission main was
assumed for developing this conceptual design. No storage facilities will be required within
the reclaimed water distribution network.
Pipe Sizing
The reclaimed water transmission piping is sized to convey the peak hour demand, which is
assumed to be 3.0 times the annual average day reclaimed water demand, and to maintain a
target velocity at the peak hour demand of 5.0 to 7.0 feet per second (ft/sec). The annual
average day reclaimed water demands evaluated ranges from 0.1 to 30 mgd. The resulting
peak hourly demands are in the range of 0.3 to 90 mgd.
Method
The unit costs for pipeline construction were estimated using a transmission main cost tool.
The transmission main cost tool is a set of spreadsheets developed to estimate pipe
construction costs. The tool includes: 1) spreadsheets for input parameters including pipe
material cost and installation rate, construction unit costs for items such as pavement
removal and replacement, sod, seed, and equipment costs for items such as an excavator,
vibratory hand compactor, and trench box; 2) a spreadsheet for developing the unit
construction cost of pipeline ($/ft), which incorporates all the costs in (1) and additional
input parameters such as depth of cover for pipes, trench width, restoration width by type
of restoration, and traffic control requirements. One cost tool was developed for PVC pipe
and a second was developed for DIP, both presented in Exhibit 1.
The unit costs for construction of various sizes of a transmission main were developed
separately for urban versus rural areas. Key assumptions used in the transmission main cost
tool for this unit cost analysis are:
• Average depth of cover for transmission mains is 8 ft.
B-2