Norwich — After 17 years of environmental studies and draft designs, the Chelsea Gardens Foundation submitted a master site development plan to the city planning office Monday and hopes to launch a major capital campaign if the plans are approved.

The project has been in the works since the early 1990s, when the private foundation sought and received approval from the City Council to lease 80 acres in Mohegan Park off Judd and Wilderness roads for a proposed botanical garden park.

“It’s been a slow process, but we have a volunteer board, a very active board,” Chelsea Gardens President Hugh Schnip said. “It’s hard to get people to get on board a project that’s been around as long as we have. We’ve done a lot of the non-glamorous work, environmental plans, engineering. Getting plans filed for approval is a great day.”

The foundation launched a capital campaign in 2011, but Schnip said it was difficult to apply for foundation grants and seek major donations without final design plans on paper.

He said some features have changed from earlier plans people have seen and will be on display at the foundation’s annual spring Butterfly Pavilion fundraiser, scheduled for June 6 to 9 at Hart’s Greenhouse & Florist, 43 Clinton Ave.

Schnip said construction of the buildings and related features for “Phase 1A” is estimated to cost $18 million to $20 million, plus about $2 million to develop the gardens and several more million for off-site work to bring utilities to the site and make improvements to Wilderness Road, where the main entrance would be located.

The 40-foot-wide entrance road would bring visitors to the 61-space parking lot and a pair of twin buildings, one housing the ticket office and the other the restrooms.

Through another gateway entrance would be the “Octagon” garden, a year-round 6,000-square-foot butterfly pavilion — a new feature not part of earlier plans, Schnip said — and an 11,800-square-foot dining emporium that could house catered events along with a cafeteria for garden visitors.

Schnip said Chelsea Gardens has been in discussions with a London-based English gardens school that hopes to make the proposed Norwich facility its U.S. base. A 5,660-square-foot garden school would be located near the Octagon garden.

The plans also show a native plantings garden and 8-foot wide trails with boardwalks snaking throughout the property.

The Commission on the City Plan will hold a public hearing on the special permit application at its May 21 meeting and also will review the site development plan.

c.bessette@theday.com