A lawsuit challenging improvement plans at Waimanalo Bay Beach Park contends the city is violating federal, state and even its own municipal laws by proceeding with the project.

The registered nonprofit group Save our Sherwoods filed the lawsuit in U.S. District Court on Thursday, the same day 28 project opponents were arrested by Honolulu police after they attempted to block construction equipment from entering the park grounds.

The group is slated to hold a news conference at the 75-acre park today providing details of the lawsuit. Maureen Harnisch, one of four Waimanalo residents filing the lawsuit, said members of the group agreed not to comment until then.

City spokesman Andrew Pereira said Honolulu officials typically don’t comment on pending lawsuits.

The 44-page filing states that in 1971, when the state owned the property, it was granted federal Land and Water Conservation Fund dollars that required “significant restrictions,” including that any new development would involve only “water- oriented recreational facilities in a beach park.”

The city’s March 2012 master plan therefore violates that agreement because it calls for a large sports complex and four ballfields, the lawsuit said. The 470 additional parking stalls in the plan far exceed what’s needed for public outdoor recreational use, the lawsuit said.

Mayor Kirk Caldwell reiterated Thursday that his plan is now to stop after the $1.43 million first phase of the project and then return to the community for further input, a stance he said is a compromise. City officials said halting the first phase, which involves grading and installing irrigation for a multipurpose sports field, parking lot and play apparatus, would cost the city $300,000.

The lawsuit said the park is on the National Register of Historic Places and therefore required Native Hawaiian organizations to be consulted before the city proceeded with its plan.

What’s more, a 2009 environmental assessment failed to adequately consider alternatives to the development, including the possibility of repairing damage at existing district parks in its vicinity, the lawsuit said.

The lawsuit said the city violated its own 2018 policy for new city projects that required its agencies to consider the impacts of global climate change before being undertaken.

The Special Management Area use permit for the project is “inadequate and based on bad information” by incorrectly characterizing the improvements “as enhancing coastal recreational facilities and scenic and open space in Waimanalo when in fact it does the opposite,” the lawsuit said.

Those bringing the lawsuit “have been left out of the critical stages of the required planning process for such a park conversion,” the filing said.

Even if the city does agree to halt at the first stage, there’s nothing to stop the city from advancing the other improvements later, the lawsuit said. “SOS members feel that the proposed development is simply a pretext for increased commercial development in the area.”

The lawsuit also brings up a point of contention: whether there are human remains within the development area. Opponents of the project say there are remains, while Caldwell said no one has found any remains but that he would stop the project if that happened.

More recently, the lawsuit said, the city failed to have an archaeologist on-site when trees on the site were knocked down and then later subsurface work commenced in April and May.

A scheduling conference for the lawsuit has been set for Nov. 25.

Save Our Sherwoods Lawsuit by Honolulu Star-Advertiser on Scribd