East Lyme — The Zoning Commission on Thursday conditionally approved Landmark Development's preliminary plan for an affordable housing development in the Oswegatchie Hills. 

Landmark has applied to rezone 123 acres in the hills as an affordable housing district, reserving 36 acres for development and 87 for open space. 

The Middletown-based company, under developer Glenn Russo, also submitted a preliminary site plan to build 840 housing units within 24 buildings.

The commission decided Thursday that only the acreage that falls within the town's sewer service district will be rezoned as an affordable housing district. 

The commission also said the developer must incorporate several modifications while, or before, moving to the next step of submitting a final site plan.

Landmark must show the proposed development has a second means of exit, obtain a permit from the Inland Wetlands Agency and provide information on the development's potential environmental and coastal effects, among other stipulations in the resolution. 

The development also must have public water and sewers, or state-approved community septic or water for portions not served by the public systems.

The development's stormwater management report also should address several concerns, which were raised in a report previously submitted by the Friends of the Oswegatchie Hills Nature Preserve.

The resolution further stipulates that the developer should address the effect pollutants generated from the development would have on wetlands, as well as concerns over the impact of drainage along the development's driveway.

Commission Chairman Matthew Walker said the conditions "are very, very stringent, and they need to be to address the very serious environmental concerns that we have with this site."

The commission unanimously voted in favor of rezoning with modifications, but 4 to 1 in approving the preliminary site plan with modifications.

Commission member George McPherson said he had concerns about how complete the information was in the preliminary plan.

Over more than 15 years, Landmark has submitted a series of applications for the hills and also filed several appeals.

Landmark's latest step follows a 2011 remand order issued by New Britain Superior Court Judge Stephen F. Frazzini. The order is part of an appeal case from Landmark over the commission's ruling on a 2005 application. 

"Some of the conditions are ones that we will comply with, and others that we feel are in conflict with the affordable housing law, and we will challenge as being illegal and not enforceable," Russo said after the meeting in response to the commission's decision. "But we are happy to move forward with an approval, and we look forward to moving to the next stage of development."

Three groups — the Friends, Save the River-Save the Hills and the Connecticut Fund for the Environment — have intervened in the application.

Roger Reynolds, legal director for CFE and Save the Sound, called the proposal "premature."

"Without crucial information about wetlands and how sewage will be handled, the application is so preliminary as to be virtually meaningless," he said in a statement. "We will review the decision in detail to do what is necessary to protect the statewide environmental treasures that are the Oswegatchie Hills and the Niantic River."

Mike Dunn, land acquisition director for the Friends, said the decision has "significant teeth" because it says that only part of the site is eligible for development and that the project must meet a strict environmental threshold.

In deliberations during several meetings, the commission noted Judge Frazzini's decision, as well as concerns from residents and groups at public hearings.

Meanwhile, Landmark has been seeking 118,000 gallons of daily sewage capacity and appealing the Water and Sewer Commission's decision to allocate 14,434 gallons to the development.

Landmark and the town signed a memorandum of understanding this spring to see if they could find a mutually agreeable parcel of land to trade for Landmark's 236-acre property in the hills.

k.drelich@theday.com

Twitter: @KimberlyDrelich