That is on top of criminal charges that may likely be filed by the Office of the Ombudsman, which investigates and prosecutes cases of government corruption.
"We will leave it to the Ombudsman to act on the criminal cases of those involved," said the source, who spoke on condition of anonymity.
The 31 accused allegedly signed about 7,000 vouchers reimbursing bogus personal expenses for repairs of over 500 DPWH vehicles and heavy equipment and pocketed the money.
The 31 will be administratively charged with one count of grave dishonesty and misconduct for every voucher they signed, the source said.
A new five-member investigative panel will convene this week and question the 31 accused "to determine who among them would ultimately be held responsible," the source added.
The panel was formed by Public Works Secretary Simeon Datumanong and headed by National Irrigation Administration lawyer Gabriel Enriquez. The NIA is an attached agency of the DPWH.
"Secretary Datumanong deemed it better to tap people outside the central office to conduct the administrative proceedings to ensure objectivity," the DPWH source said.
The old panel was dissolved recently after it was discovered during the course of the investigation that three of its members — Abraham Divina, Oscar Abundo and Emily Tanquintic — were themselves allegedly involved in the scam.
The anomaly began sometime in the 1980s and was only discovered seven months ago. In some instances, investigators found that the bogus repairs cost much more than the value of the vehicle.
In one case, it was discovered that P900,000 was spent only last year on fictitious repairs of an old model Mercedes Benz car.
In previous surveys, the DPWH was seen as one of the most corrupt government agencies along with the Bureau of Internal Revenue, Bureau of Customs and the Philippine National Police.
Last month, US Ambassador Francis Ricciardone said in an interview that corruption is one of the country’s biggest problems that is driving away foreign investors, triggering a firestorm of criticism from some lawmakers.
Upon assuming office in 2001, President Arroyo pledged to root out corruption, a serious problem that hounded past administrations.
On January 2001, Mrs. Arroyo’s successor, Joseph Estrada, was ousted in a military-backed popular protest after he was accused by an estranged drinking buddy of taking bribes from illegal gambling bosses, misusing state funds and profitting from insider trading.
Arrested last year, Estrada is now detained in a military hospital and currently on trial for plunder, a capital offense.
In February 1986, the late dictator Ferdinand Marcos was forced into exile by a popular uprising after his 20-year regime collapsed under the weight of corruption and human rights violations.
He and his wife Imelda, as well dozens of their cronies, allegedly stole billions from government coffers and drove the country into bankruptcy and poverty.