Prince William County and the City of Manassas are expected to break ground on an estimated $50 million expansion of the regional jail in two months, said Col. Skip Land, jail superintendent.

The Prince William-Manassas Regional Adult Detention Center has two buildings and a work-release center behind the courthouse in Manassas, and is designed to hold 740 inmates daily.

"Last Sunday, we had 754 in-house," Land said.

That doesn't include at least 75 inmates transferred to Peumansend Creek Regional Jail in Bowling Green, which is more than an hour away in Caroline County, Va., and about 25 others transferred to other jails throughout the state. In addition, there were 18 inmates with electronic surveillance, or ankle bracelets, on home detention Tuesday, Land said.

According to projections, the jail will house 1,514 inmates daily by July 2013. That and current crowding prompted the expansion, which could be partially completed in two years under a five-year construction plan, Land said.

The expansion will add 400 beds, 110 employees, a new kitchen and medical facilities, among other improvements, Land said.

The rise in the number of inmates has followed the county's population boom, said Maj. George Murphy, who is in charge of the jail expansion.

The county's population has risen to 332,555 from 280,813 in 2000, according to the U.S. Census Bureau. In 2000, the jail had fewer than 500 inmates daily.

"Just a few years ago, we had too many beds," Board of County Supervisors Chairman Sean T. Connaughton (R) said.

That was after the county was sued in 1988 by Henry Perry-Bey, an inmate who wrote his lawsuit by hand, complaining of unbearable conditions at the jail.

"I remember when he handed me the letter to mail," said Sheriff Glendell Hill (R), former superintendent of the jail.

At the time, the jail housed inmates in one building, which was completed in 1982 and had a capacity of 175 prisoners. The number of inmates was double the capacity.

A federal judge sided with Perry-Bey, and the county and city responded by opening a work release center in 1988 and a additional modular jail in 1989, Hill said.

The extra beds, often used to house federal inmates for extra revenue, did not last long as new residents flooded the county and the number of inmates increase as well.

Peumansend Creek has been a relief for the jail, Hill said. Prince William often runs over its designated 75 inmates there. Land said 95 were there Tuesday.

"The concern is how long will those beds be available," Hill said.

The first phase of the jail expansion will add 200 beds and 60 employees, Land said. The jail hired 13 guards and support staff this month to help with transportation, booking and security of the hole that will be in the back of one building during construction, Land said.

The expansion is not only about adding beds but also about improving outdated services and facilities, Land said. The kitchen, originally built to make three meals a day for 175 inmates, handles nearly 1,500 meals plus bag lunches daily, he said.

In addition, mentally ill inmates need separate housing, which they will get under the expansion, Land said.