Annual program keeps Louisville faucets flowing

The Louisville Water Company, a municipal utility, commits nearly $10 million a year to replacing and rehabilitating the Kentucky city’s water distribution system.

The Louisville, Ky. Water Company’s Main Replacement and Rehabilitation Program (MRRP) is an annual program that addresses the replacement or rehabilitation of water main facilities in the distribution system.

Initiated on a small scale in 1976 with a capital budget of approximately $50,000, the program initially addressed only isolated areas of the system.

But, by 1983, the budget had expanded to $3 million, and the program involved the replacement of eight miles of failing water mains within the system.

Today, the water company commits approximately $10 million annually toward the replacement or rehabilitation of water main facilities in its distribution system.

This dollar commitment allows the Louisville Water Company to renew or rehabilitate approximately 1 percent of its system on an annual basis.

The water company currently maintains more than 2,900 miles of water main and provides service to more than 240,000 households and businesses in the Metropolitan Louisville Area.

Originally, the MRRP addressed only the abandonment of undersized and failing water facilities within the distribution system.

In 1985-1986, the Louisville Water Company introduced a rehabilitation component to the MRRP, which offered the opportunity to clean and cement mortar line the interior wall of unlined cast iron water mains.

The process, termed “cleaning and lining,” provides the water company with an economical alternative to replacing water mains.

This method is only used on water facilities that are still structurally sound yet experiencing internal corrosion due to the lack of a cement-mortar lining.

Every two years, the water company publishes a report identifying the capital expenditures for the MRRP over the next two-year construction cycle.

In order to develop this report, the distribution system is monitored through a computer model known as the Pipe Evaluation Model (PEM). The PEM, subdivided into 22 geographical areas, aids in the identification of water main facilities by the size, type and age of the facility, as well as the number of main breaks or joint leaks that have occurred on the facility.

Water main facilities are numerically evaluated based on 23 criteria that fall into four broad categories: geographical, hydraulic, maintenance and quality of service.

The results of the evaluation process will produce a list of candidates focusing primarily on four types of replacement and rehabilitation:

* replacement of high maintenance water mains;

* rehabilitation of structurally sound water mains by cleaning and cement-mortar lining;

* installation of grid connections on dead-ended or poorly circulating mains; and

* abandonment of unlined cast iron water mains that parallel existing water mains designated to be replaced or rehabilitated.

The MRRP’s $10 million annual budget comes from three different sources: depreciation of the existing water main distribution system, the MRRP Reserve Fund and reinvestment of profits from sales.

The Louisville Water Company uses straight-line depreciation of its existing fixed assets, and each year, the cost of depreciation of the existing water mains in the distribution system is recovered through water rates that have been established for that year.

Approximately 40 percent of the profits from the sale of water is reinvested back into the infrastructure of the Louisville Water Company’s distribution system.

The MRRP program can be adopted by any agency faced with the problem of infrastructure failure.

The process involves identifying the infrastructure facilities that would be under consideration.

The Louisville Water Company maintains an accounting-based database identifying every pipeline installed within the system.

This database includes such information as the size, location and type of material of the pipeline, along with the joint material type for each facility. The information is then transferred into the PEM for use by the engineering staff in developing the MRRP.

Additionally, the Louisville Water Company continues to strive to maintain the MRRP as a sound program, environmentally.

Louisville Water staff continually seek out new construction techniques and technologies for replacing and rehabilitating existing water mains that have the least effect on the surrounding environment.

Before a construction technique is adopted into the MRRP, pilot projects are used to survey the effects on the environment and affected customers.

Water main replacement which usually involves extensive trenching continues to be the most disruptive form of construction for the MRRP.

The staff continues to review new techniques for trenchless main replacement and private service line renewals, with a goal of allowing Louisville Water to install new water main facilities without disrupting the environment.