Preston ― The sound of silence should be coming soon to the former Norwich Hospital property in Preston as the environmental cleanup is completed, except for the need to spread clean fill over an area of buried contaminated soil.

“All the digging is done,” said Sean Nugent, chairman of the Preston Redevelopment Agency overseeing the town’s cleanup of the 393-acre former state hospital property on Route 12.

The town remains on track to complete all cleanup and paperwork to turn over the property to the Mohegan Tribe for redevelopment by Dec. 31 of this year, Nugent said. The property will be turned over to Mohegan, the tribe’s gaming and entertainment corporation.

The tribe has not announced an update of their plan to develop the site.

The cleanup plan called for a portion of the contaminated dirt to be consolidated in one area on the site that will be covered with clean fill and capped with four feet of topsoil. Contractors had been using clean fill excavated from the property to cap the consolidated areas, but Nugent said there is not enough available clean fill to finish covering the final consolidation area.

Finding the necessary 3,000 to 4,000 cubic yards of clean fill was difficult, but Nugent said the material has been ordered and now is being tested to make sure it complies with state regulations for clean fill before it is spread on the property.

The entire property has been divided into seven major parcels for the cleanup and future development purposes. As each parcel was cleaned, the redevelopment agency submitted paperwork to the state Department of Energy and Environmental Protection seeking certification that the cleanup met state standards.

The town and Mohegan tribe have received notification from DEEP that three parcels have met the state standards. The town and tribe submitted information for state review on a fourth parcel, and town and tribal officials are reviewing work on the final three parcels to be submitted for state approval.

DEEP spokesman Ethan Van Ness said the review process begins with Preston’s licensed environmental professional verifying that a certain parcel has been cleaned and that it meets the state Remediation Standard Regulations or RSRs.

DEEP officials have completed their verification of three of the former Norwich Hospital parcels and verified and issued a determination that no audit is required of the cleanup verification.

DEEP is reviewing the verification of a fourth parcel and expects to issue a determination soon, Van Ness wrote in an email to The Day.

Most of the dozens of institutional buildings, support buildings and the entire network of underground tunnels that once criss-crossed the campus have been demolished. The cleanup plan left five buildings standing in advance of conveying the property to Mohegan.

The historic Administration Building, the first hospital building, has been abated and received a state preservation grant. The Gallup, Mitchell and Ray buildings have been abated of contamination and stand as shells for Mohegan to demolish, Nugent said. The Chiller building also has been abated and will be used by Mohegan as a development staging area.

The Mitchell Building crosses the Preston-Norwich border. It is mostly in Preston, with about 5% of the building sits over the Norwich line. Preston officials placed notices on both the Preston and Norwich land records of the intent to demolish the Mitchell Building.

About 49 acres of the former Norwich Hospital property is in Norwich. Unlike Preston, Norwich never took ownership of its portion of the campus, and it is privately owned by Thames River Place LLC. It remains dominated by decaying buildings and overgrown vegetation.

Norwich has applied for a $250,000 state planning grant to help the owner assess the property.

Nugent said Preston officials have not had any contact with the owners of the Norwich portion of the former hospital campus.

The final cleanup was funded through a $7 million state grant and $2 million state loan to the town. Preston used $5 million of the grant to complete its work, and the remaining $4 million will be available to Mohegan for additional work to fit its development needs.

Mohegan has not announced any updates to a 2017 conceptual development plan for the Preston property, which cannot include gambling facilities.

In an interview with The Day in June, Ray Pineault, president and CEO of Mohegan, said the original plan for the property called for Mohegan to market it to developers interested in building such attractions as a theme park, an indoor waterpark and a hotel as well as a marina on the Thames River.

“We’re going to look at development opportunities,” Pineault said at the time, adding current interest rates and economic uncertainty could delay things.

c.bessette@theday.com