Commission approves Norwich site changes to cap contaminated soils, add parking at Panema South Mill
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Summary
The commission approved a site modification at 555 Norwich Avenue that adds a 320-foot retaining wall, paved parking above an engineered control to cap contaminated soils from a former manufactured gas plant, and raised planter boxes; DEP approval and an environmental use restriction on the deed were discussed.
The Norwich Planning Commission on March 17 approved a site modification for the Panema South Mill complex at 555 Norwich Avenue that calls for a 320-foot retaining wall, paving above that wall to cap contaminated soils and an additional parking bay.
Brandon Hanfield, a licensed professional engineer with Yantic River Consultants, said the proposal eliminates a green embankment along the public pathway and replaces it with a retaining wall to create more room to place and cap soils on-site. The change creates pavement above the wall and space for an added parallel parking bay; Hanfield said the configuration gains about 23 parking spaces to serve the project's 148 units and the recently approved Panema Landing restaurant.
Brian McCann, a licensed environmental professional with BGT Environmental, explained the environmental rationale: the engineer control area contains soils with contamination levels above the pollutant mobility criteria and is associated with a former manufactured gas plant on the site. He said a hybrid approach — a composite asphalt barrier on the building side of the wall combined with a liner riverside of the wall — is being discussed with the Connecticut Department of Energy and Environmental Protection (DEP). "Our plan was to try to cap as much of the existing soil on-site beneath the cap, to keep the project financially viable," McCann said.
McCann told the commission that if DEP does not approve the proposed hybrid composite barrier, the project would implement the impermeable liner design that already has conditional approval. He also said the project will record an environmental use restriction on the deed after the engineered control is installed and will submit as-built documentation and financial assurance for long-term maintenance.
Commissioners asked about fall-protection and barrier design atop the retaining wall; Hanfield said the structural contractor will design a traffic barrier or railing and the building official will review fall protection as part of the building-permit process. Planning staff recommended approval and noted the original erosion-and-sediment bond from the prior approval is sufficient to cover this modification.
A motion to approve the modification with conditions in staff's memo and to require the plan to return to the commission if the engineered-control area is significantly changed passed by voice vote.
The commission's approval includes a condition that large changes to the engineered control area must return to the commission; DEP review and recording of an environmental use restriction will be required as part of state oversight.
