The Department of Energy is fining CH2M Hill Hanford Group $302,500 for safety violations related to last summer's spill of radioactive waste at the Hanford tank farms.

"It was only mere chance that prevented personnel from being directly contaminated by significant quantities of tank waste during the course of the event," said a letter sent Thursday to the DOE contractor from the DOE Office of Health, Safety and Security.

On July 27, about 85 gallons of radioactive waste spilled onto the ground as workers were operating a pump to retrieve waste from Tank S-102 at the end of a night shift. The spill was not discovered for eight hours.

DOE said it was concerned about the delay in detecting the spill and also "long-standing engineering lapses" that led to the spill. The pumping system lacked back flow equipment that would have prevented waste from backing up into and breaking a rubber hose not designed to contain radioactive waste.

More than 10 months later, the spill continues to be a problem.

Work to pump waste from DOE's older leak-prone tanks into newer double-shell tanks stopped when the spill was discovered and has yet to resume.

CH2M Hill appeared close this week to beginning retrieval of waste from the first tank since the spill occurred.

But Wednesday a new robot lowered into the tank, C-109, lost its tread on one track that helps it crawl over the solid waste at the bottom of the tank. The robot is needed to break up and move the waste.

The robot was not designed to be taken out of the tank after it became contaminated with radioactive waste, and CH2M Hill was still considering Thursday what to do about the damaged equipment.

Work to clean up the spill is expected to continue through the end of September. CH2M Hill has excavated 60 drums of contaminated material so far.

The DOE fine covers nine violations, with $110,000 of the fine assessed for one violation -- CH2M Hill's failure to identify and correct a quality problem, according to DOE.

DOE is concerned "by the history of significant radiological events at the tank farms over the past three years, and (its) consequent inability to effectively resolve the underlying issues," said the letter to the contractor.

Problems included a 2005 incident in which workers were contaminated with radioactive waste when hoses were removed from Tank C-202.

"The underlying issues that led to this event are considered to be similar to those associated with the S-102 spill event," said DOE's preliminary notice of violation for the fine announced Thursday. In both events, an analysis of hazards did not identify the potential for a spill, according to DOE.

Other violations covered by the fine included inadequate worker training, inadequate procedures and failure to follow procedures before and after the spill.

The fine would have been greater, but DOE reduced it by $192,500 because of CH2M Hill's actions since the spill.

"DOE found your event investigation to be detailed and thorough and found your corrective actions to be appropriate," said the letter to CH2M Hill.

However, DOE remains concerned if corrections will be sustained in light of distractions caused by the end of CH2M Hill's contract.

CH2M Hill has operated Hanford's tank farms holding 53 million gallons of radioactive waste for 11 years, but DOE last week announced that Washington River Protection Solutions would take over the tank farms when CH2M Hill's contract expires this fall.

To make sure CH2M Hill stays focused, DOE is requiring it to report on the effectiveness of its corrections to DOE headquarters in six months.

"We have a talented and experienced work force and have involved them at every level to make sure we all understand what happened and why," John Fulton, president of CH2M Hill, said in a statement. "The corrective actions that we have taken since the incident have made us a stronger and safer operating company."

The fine announced Thursday comes under the authority of the Price Anderson Act Amendment, which indemnifies companies that do nuclear cleanup work for DOE but issues fines for violations of nuclear safety requirements.

Earlier DOE withheld $500,000 from CH2M Hill's pay because of the spill. In addition, the state of Washington fined DOE $500,000 because of the spill. Half of that fine may be forgiven and the rest will be paid by CH2M Hill through environmental protection and worker safety projects and a direct cash payment.

In addition, the Environmental Protection Agency is expected to issue a fine for problems in the response to the incident.