When Gov. Dannel P. Malloy’s administration needed to refill 990 executive branch vacancies last month it decided it couldn’t do without the experience of 80 retirees.

Those 80 state employees, who will collect both a pension and a paycheck, are already back at work in many cases and will have 120 days to work before their contracts will need to be renewed by the administration.

According to administration documents, about 30 of the “temporary worker retirees” help plow Connecticut’s highways, repair vehicles, and fill the stockroom during the winter season. Several more are engineers at the Department of Transportation overseeing everything from bridges to highway design.

Five returned to the Department of Motor Vehicles and four were hired back by the Department of Emergency Services. Two, including a deputy commissioner and education bureau chief, were returned to the Education Department, while the Department of Developmental Services saw the return of 10 of its workers.

Office of Policy and Management Secretary Ben Barnes said in early October that with the rate of retirements, it was more than likely the state would look to hire back retirees.

“I anticipate there will be some use of TWRs, given that there were 650 retirements in one day and they were all senior people,” he said. “With a lot of people walking out the door at one time it sometimes make sense to keep somebody for a month or two while they work to find a replacement.”

The labor concessions agreement passed in August anticipated about 1,000 vacancies created by retirements to achieve $65 million of savings. But since the beginning of the year, more than 2,700 have retired. Barnes said there are currently about 3,500 vacancies in state government.

The flood of retirements was driven by concessions in the labor deal that made changes to the retirement benefits of state employees. The changes reduce their cost of living increases and increase the penalty for retiring early.

Former Gov. M. Jodi Rell, a Republican, authorized the rehiring of 509 executive branch retirees during her last year and a half in office. Most of the rehiring was necessary after the 2009 early retirement incentive, which saw 3,900 state workers retiree.

A 2009 executive order from Rell limits the use of retired workers to no more than two 120 day contracts. Barnes has said he imagines very few will be necessary beyond the first 120 days.

State employee unions are generally critical of the use of temporary retirees to fill permanent positions.

“It clearly makes more sense to fill vacancies with full-time public service workers,” Matt O’Connor, spokesman with CSEA/SEIU Local 2001, said in October.

However in the interest of maintaining service continuity in the midst of mass retirements the temporary workers policy may be practical so long as the arrangement is very brief, he added.