The firm building the Greenbush commuter rail line on the South Shore of Boston has been fined $150,000 for wetlands violations near the construction.

It is the second environmental fine for builder Cashman/Balfour Beatty and the Greenbush line in the past six months from the state Department of Environmental Protection.

The company was fined over permit violations that harmed wetlands and bodies of water adjacent to construction.

''To discover repeated violations involving actions that we know are preventable is regrettable," said Richard Chalpin, director of the state's Department of Environmental Protection's Northeast regional office.

In one incident, heavy rains last November overwhelmed a detention basin, causing sediment-laden storm water into an adjacent brook and wetlands.

In addition, state officials found Cashman/Balfour Beatty failed to contain storm water runoff into sensitive vernal pools. In another, state inspectors found water going directly into a brook without first going through a sedimentation tank, as required.

In addition to paying the two penalties, which total $245,000, the firm must repair the areas. State officials acknowledge that Cashman/Balfour Beatty has made significant progress on the repairs, including plugging outlets and revamping drainage.

''The T expects all of its contractors to operate within the parameters of approved environmental permits," said MBTA spokesman Joe Pesaturo. ''If they make a mistake, they have to pay for it, and that was the case here."

Source: EPA