The state’s largest utility company hampered regulators’ ability to review its response to a 2011 storm that left more than 800,000 customers in the dark and cold, Attorney General George Jepsen alleged Tuesday in a petition to regulators.

Jepsen asked the Public Utility Regulatory Authority to penalize Connecticut Light & Power for failing to hand over internal documents, handwritten notes, and emails related to restoration estimates for the October 2011 Nor’easter.

Regulators already concluded their review of the response to that storm last summer, but Jepsen’s investigation later turned up handwritten notes from senior personnel showing that the utility ignored observations from its employees in the field, telling executives it would take 11 days to restore service to most of the hardest hit portions of the state.

Now, CL&P wants permission to recover the $175 million it spent on the storm through a rate hike. Jepsen wants to make sure ratepayers aren’t on the hook for all of the costs related to that storm.

The October 2011 Nor’easter left a large portion of the state without power for more than a week and in some cases up to 11 days. The outage and the utility’s response led to the resignation of then-Chief Operating Officer Jeffrey Butler and prompted legislation that would allow regulators to hold utility companies accountable for timely restoration efforts.

“As the restoration from the October Nor’easter proceeded, CL&P committed to the governor, municipal officials and its customers that it would restore 99 percent of all homes and businesses in each town it served by midnight on Nov. 6,” Jepsen said. “The documents produced are relevant to whether the Nov. 6 restoration projection was reasonable and whether CL&P knew that estimate was attainable.”

But PURA already completed its review of Connecticut Light & Power’s response to the storm last summer.

In its final decision last August, PURA concluded that CL&P’s performance in the aftermath of the 2011 storm was “deficient and inadequate” in a number of areas, including “development and communication of restoration times to customers.” PURA retained the authority to determine the appropriate amount of CL&P’s storm recovery for the 2011 events in a future proceeding.

In the petition he filed Tuesday, Jepsen asked regulators to penalize the utility for failing to disclose this information during the initial review.

Connecticut Light & Power issued a statement Tuesday saying it disagrees with Jepsen’s position.

“Connecticut has a thorough regulatory process and the Attorney General’s filing is part of that, however, we disagree with his position,” the utility said in a statement. “All of the information in the AG’s filing refers to the 2011 storms, which CL&P voluntarily provided to his office. We will address these claims during the course of this proceeding.”

According to Jepsen these are excerpts from some of the documents CL&P failed to disclose to regulators:

—A handwritten note by CL&P’s senior official in charge of restoration in the hard-hit Central Division, dated Nov. 1, saying she provided a 99 percent restoration estimate of Nov. 9 at 6:00 p.m. if she received 20 additional crews.

—Handwritten notes dated Nov. 1, made by another senior CL&P official who surveyed area commanders for their 99 percent restoration estimates. The notes indicate many commanders projected restoration dates beyond Nov. 6 for the towns in their area, and as late at Nov. 9 for Hartford.

—An email, dated Nov. 3 at 11:59 p.m., from a CL&P day shift commander for the Simsbury area work center providing revised restoration estimates for a few towns in the Farmington Valley that were requested by superiors, while noting that they are “Quite the work of fiction…I took a swag [scientific wild-assed guess]…I don’t think this should be shared with any town official as it is not really a good picture of what we are doing.”

—An entry log of the CL&P Emergency Operations Center, from the morning of Nov. 4, saying, “Do not promise by community…some communities may be over 1% [unrestored] by midnight Sunday making us unable to reach our goal the way it is currently stated.”

—Handwritten notes of the CL&P Central Division Commander from a 6:00 a.m. call on Nov. 6 noting that she had reported to her superiors that even if she received expected additional crews, many towns would still have 50 percent outages by midnight Nov. 6 and would not be 99 percent restored until as late as Tuesday, Nov. 8.

—A requested report from CL&P to the Governor’s Office of expected restoration times, sent at 8:49 a.m. on Nov. 6, which appears to completely ignore the projections reported at 6:00 a.m. that morning by the Central Division Commander and containing no restoration projections beyond Nov. 7.

—Handwritten notes of a senior CL&P commander working in the Simsbury area work center entitled, “Storm Alfred Restoration Observations,” which included the following: “[m]ore severe damage, widespread,” “[n]o acknowledgement of damage extent when providing restoration projections (mgmt. v. public goals)” and “99% for ea. town@ same time unrealistic.”