The public works department (PWD) does not want the forest department to be involved in setting up a garden on the roof of the underground parking plaza at Laldighi, fearing the structure would be damaged through careless execution of the project.

The forest department, ready with designs and sketches for the garden, has expressed surprise over the PWD’s stand.

“The parking plaza will be an underground structure. Hence, special care has to be taken while planting trees on the roof. We have to be careful in selecting the saplings, so the structure does not get damaged by the roots,” said P.K. Deb, chief engineer, PWD.

According to the plan, the garden will be spread across one lakh sq ft and comprise ornamental plants, Australian grass and fountains. The estimated cost has been pegged at Rs 20 lakh.

Engineers of the PWD feel the task should be left to the department, as several technical aspects need to be taken into account while planning a garden on the roof of an underground structure like the parking plaza.

“Not that we are ruling out completely the forest department’s involvement. We would certainly encourage suggestions from them, but would prefer to execute the project ourselves,” said a senior official in the department.

Reacting to PWD’s decision, deputy conservator of forests (urban forestry) Somnath Mukherjee said: “It’s unfortunate that we have been considered incompetent for the project. Had we been given the responsibility, we would have paid more attention to it.”

Forest department sources said the plans and primary sketches of the garden are ready. The department was even planning to make a presentation before the PWD engineers. “We had taken into account the sensitivity of the structure while preparing the design,” Mukherjee added.

The two-storeyed plaza will have space for 700 cars, half reserved for state vehicles.