Officials broke ground on the new building in a Monday afternoon ceremony.
After its expected May 2013 completion, the headquarters will have 60,000 square feet in customer service and material and equipment storage located on 28.5 acres.
Currently, the utility has 21,000 combined square feet on 14.5 acres. Since that facility was completed in 1963, membership has grown from 13,000 to 41,500.
"For me, the most exciting part is to have adequate space," said Manager Bill Long. "We are bursting at the seams now to store equipment and material. We will have plenty of space and room to grow. This will be an adequate sized facility to serve our members."
The new facility will include a customer services building with three drive-through payment areas, an increase from the one drive-through currently being used. It will have a 300-person-capacity auditorium that will be available for members to use. Connected to the building will be the engineering and operations building.
An area on the back of the property will house the utility's trucks and equipment. The campus also will have a lake for public use. The branch office in Fulton will also remain open, Long said.
The facility has been in the planning stages for about seven years, Long said. It was designed by Pryor amp& Morrow architects and engineers, and construction will be done by Worsham Brothers from Corinth.
Long said the $8.7 million building will be funded by the existing rate base.
"We are not anticipating a rate hike to fund this building," he said.
Tombigbee mostly serves customers in Lee and Itawamba Counties but also has members in six adjoining counties. It currently has 135 full-time employees.
"I'm so excited to have this new facility for us," said board chairman Pat Carr. "We deserve it, and I'm proud to have it. Bill Long and all of the committees involved have done a fantastic job."