Three of Deepwater Wind's turbines stand in the water off Block Island, R.I., in 2016. The company wants to build a wind farm off the coast of Maryland. (Michael Dwyer/AP)

Deepwater Wind, which operates a wind farm in waters off Rhode Island, wants to build another one off the Maryland coast. But before its proposal can go forward, the company needs to know what lies on the sea floor here — and within the ancient layers of sediment beneath it.

So geologists, marine biologists and archaeologists will spend the next couple of months seeking answers, scouting the potential footprint of a wind-energy project planned near the mouth of the Delaware Bay.

The survey, being launched this week, is a key step in advancing a proposal vying to be the nation’s second offshore wind farm.

“You can imagine, if you’re going to build a house, you want to know more than just what’s the geology in your town,” said Jeffrey Grybowski, chief executive of Deepwater Wind. “We need to have a very detailed picture of the ocean floor.”

That includes any hills or valleys, boulders or sand dunes, thriving habitats for aquatic life, and even any shipwrecks.

The project, known as the Skipjack Wind Farm, is one of more than a dozen offshore wind proposals considered the closest to becoming reality. But in the year and a half since the Block Island Wind Farm began operating off Rhode Island, none of those new projects has started construction. They all have to navigate a lengthy federal review process and, in some cases, opposition from concerned beach communities.

Grybowski said he is confident this summer’s surveying will allow the Skipjack project to jump forward on a timeline that calls for construction to begin in 2021 and operation in 2022. The work will determine exactly where — in measurements down to the foot — each of a fleet of 15 wind turbines will be built.

“This is not about finding sort of a fatal flaw for the whole site,” he said. “This is about understanding, with a lot of precision, where each foundation will go.”

Skipjack farm is proposed to be built northeast of Ocean City, closer to the Delaware coastline, at least 20 miles off the coast.

Deepwater officials say they have not selected a turbine model yet, so they can’t say what the precise height will be. However, the company has said it is considering models up to approximately 670 feet above the sea.

It is separate from a proposal by U.S. Wind, which would be located farther south with plans for 32 turbines at least 17 nautical miles from shore. The U.S. Wind project has drawn opposition from Ocean City leaders who are concerned that the wind farm could depress tourism and that U.S. Wind could eventually build twice that many turbines as close as 13 nautical miles from shore.

U.S. Wind conducted its ocean floor surveys in 2015 as it was performing other preliminary work on the project. The company does not plan to make additional surveys until after federal regulators approve its plans for construction and operations, a step officials expect next year, spokesman Greg Tucker said.

As Deepwater Wind finalizes its own construction plans, it is counting on collecting massive amounts of data this summer to guide the process. It is an undertaking that will cost more than $5 million and involve five vessels.

One vessel was recently docked at General Ship Repair in Baltimore’s harbor, receiving finishing touches that will allow it to spend weeks at a time using multiple types of sonar to scan the seabed 24 hours a day. The Danielle Miller is normally a work boat, ferrying supplies to larger ships or oil rigs, but it has been outfitted for its next assignment with three separate sonar systems and a command center to gather the data they observe.

One such system is contained in a yellow torpedo-like device that will be dragged behind the Danielle Miller; another extends from a pole that rests along the boat’s deck but swings downward into the water to scan the bottom. Each sends sound waves and measures reverberations to map the sea floor, which is about 100 feet deep in that part of the ocean.

The combination of sonar signals, some in chirps, others in thumps, gives the scientists aboard the ship a multilayered map of the texture, shape and content of the sea floor, as well as the properties of Earth’s crust below it, as much as 250 feet deeper, said Richard McGee, a marine geophysicist who is managing the project for Oceaneering, an engineering contractor working for Deepwater.

“This region has some very interesting geology,” McGee said.

Beneath the waters off the Delmarva Peninsula is a formation known as the Delaware River paleochannel, an ancient estuary and network of tributaries buried beneath the sandy coastal plain. Deepwater is looking for the older — and firmer — portions of that geologic formation as the perfect places to build the foundation of a towering wind turbine, said Zach Finucane, the company’s foundation package manager.

Joining Deepwater and Oceaneering’s crews will be half a dozen marine biologists. In addition to its radar technologies, the Danielle Miller has been outfitted with infrared cameras that the biologists will use to track any whales, dolphins or other ocean life, to ensure the surveying work, not to mention a wind farm, does not disrupt their habitats.

The survey’s observations will become public when Deepwater is ready to file plans with the federal Bureau of Ocean Energy Management, and Grybowski said they could be of interest to more than just his company. Deepwater plans to submit its construction operations plan in the first half of 2019.

“We’ll know a lot more about the ocean just off the Delmarva Peninsula,” he said.

— Baltimore Sun