The state plans to help the towns of Groton and Ledyard buy land around the Naval Submarine Base to prevent development from encroaching on base operations.

Three local legislators said the land deals are meant to enhance the military value of the base to help protect it during a future round of base closings.

"The base is boxed in on all sides. This added land would provide a buffer between the base facilities and neighboring properties, which is an important part of the scoring matrix used by the military to assess bases and make closure decisions," state Sen. Andrew Maynard, D-Stonington, said Wednesday in a joint statement with representatives Tom Reynolds, D-Ledyard, and Elissa Wright, D-Groton.

If the deals to fund the purchases to prevent development are approved by the State Bond Commission Friday, Groton would receive $455,000 to buy property at the intersection of Crystal Lake Road and Military Highway, and Ledyard would receive $225,000 to buy close to 20 acres of property alongside the base on Kings Highway (Route 12).

Across the street from the main entrance of the base, the Groton parcel is the site of a former dry cleaning business that has been closed for several years. The deteriorating property is an eyesore and security issue, Groton Town Manager Mark Oefinger said.

"This is a major entrance to a major military facility that desperately needs some enhancements," he said.

Acquiring the property should not cost the town, Oefinger said, adding that some of the funds would be used for environmental cleanup.

The town also now may be able to proceed with long-awaited improvements to the intersection that would improve traffic flow, Oefinger added.

The property in Ledyard is vacant land near the northern perimeter of the base.

"Preventing encroachment is much easier than trying to correct it," said Bob Ross, executive director of the state's Office of Military Affairs.

The base is home to 15 fast-attack submarines, more than 70 commands and roughly 22,000 active-duty service members and civilian workers.

Maintaining an undeveloped buffer is a high priority for the Navy, said Capt. Marc W. Denno, base commander.

"As populations grow surrounding bases, we have to be mindful of the fact that we need to maintain our security, access and safety of the general population," he said in a recent interview. "These are forward-thinking projects that will do that."

The Pentagon is calling for two new rounds of base closures, in 2013 and again in 2015. Influential members of Congress have promised not to let the plan move forward for 2013, but the secretary of defense has said he will try again next year.

Chastened by the base nearly closing during the 2005 Defense Base Closure and Realignment process, the state legislature authorized $40 million in 2007 for improvements at the base. Connecticut was the first state to fully fund a construction project on a military base.

Gov. Dannel P. Malloy said earlier this month at the base that $29 million remains of the $40 million and he's anxious to spend it. Denno said that after the properties are purchased, reducing energy costs likely will be the state's next big project to complement the Navy's investments in the base.