Two months after Angela and Matthew Cibelli moved into their family's dream home in Uwchlan Township in 2016, a representative of Sunoco Pipeline LP stopped by their house to outline upcoming construction plans for the Mariner East project.

"What construction?" replied Angela, unaware that the previous owner had signed an easement allowing Sunoco to occupy their backyard to build two new underground pipelines across their Marchwood property.

Shannon Healey experienced a similar sinking feeling when she learned Sunoco planned to dig up the property that she and fiance Kevin Bullman bought last year on Lenni Road in Middletown Township. Sunoco had paid the previous owner for the easement.

"We wouldn't have bought here if we had known," said Healy.

The $5.1 billion Mariner East project, which aims to deliver 675,000 barrels a day of propane and other highly volatile gas liquids across Pennsylvania to Marcus Hook through three pipelines, has produced considerable anxiety in some neighborhoods in Chester and Delaware Counties, the most densely populated areas along its 350-mile route.

The project has unsettled the residential real estate market, as some fearful homeowners sold out ahead of construction, and some buyers moved in unaware of the forthcoming disruption. Many who remained are basically stuck until the dust settles, uncertain of the value of their homes.

"I'm scared of it," said Kate White, 57, whose house on Lenni Road in Middletown is less than 10 feet from the pipelines. "I would love to move, but who would buy my house now?"

Many homeowners said they were aware their property contained an easement for an 87-year-old Sunoco fuel pipeline, but did not know that it was refurbished in 2014 as the Mariner East 1 to transport gas liquids from the booming Marcellus Shale region.

And others said they had no clue that Sunoco planned to build two new Mariner East pipelines to expand the system's capacity from 75,000 barrels a day to 675,000 barrels a day, though the project had received media coverage, and some opposition groups formed to challenge it.

"When I found this house, I thought it was perfect," said Ray Magliano, who paid $300,000 at the end of 2015 for a three-bedroom house on Wildwood Avenue in Glen Riddle, not knowing that Sunoco had paid the previous owner to expand its easement. The new pipelines run 36 feet from his front door.

"At the end of the day, I don't want to live here anymore," said Magliano. He said a lawyer advised him it would cost more than it was worth to challenge the sale. Zillow, the real estate website, now estimates his home is worth 10 percent less than what he paid for it.

Real estate professionals say it is impossible to measure the pipelines' impact on home values until the project is completed and the physical scars on the landscape heal.

"After the grass grows back and things settle down, then I'd think you'd have a better sense of the impact on property values," said Noelle Barbone, an agent for Weichert Realtors.

But the project's completion is indefinite.

The Mariner East 2, the first of the two new pipelines, is nearing completion, though the project has been interrupted and pushed back several times because of regulatory and legal challenges. The Pennsylvania Public Utility Commission in 2014 affirmed the project as a public utility, allowing it to obtain easements by eminent domain.

The PUC is currently reviewing the latest stoppage, which affects construction in West Whiteland Township in Chester County, but also halts operations on the existing Mariner East 1 pipeline. Sunoco is owned by Energy Transfer Partners LP of Dallas.

When the Mariner East 2 is completed, Sunoco plans to begin work on its parallel expansion pipeline, called the Mariner East 2X. The company has not announced an expected completion date for the ME2X.

With much of Mariner East's pathway currently heaped with pipe and dirt, and shrouded by 25-foot high sound barriers, brokers say it is generally not a good time to sell.

"The sites are pretty ugly and invasive," said Clark Kendus, a broker with Patrick Welsh Real Estate in Swarthmore. "If you were backed up against it and tried to sell it while it's going on, that would be a detriment."

Brokers cited conflicting anecdotes about recent pipeline sales. Some say the market is so strong for sellers that the short-term visual impact has barely impacted prices.

"Currently, there is a shortage of inventory, and I don't think it will affect values significantly," said Joe McArdle, a sales associate at Keller Williams Realty Group in Limerick.

He said his firm recently worked with a buyer who expressed concern about a pipeline in the front yard of a property. "The buyer went ahead, and in the market we're in now, there was still a bidding war," said McArdle.

"There will be some people who would never purchase property near a pipeline, and there will be others who are perfectly comfortable with it," said Kathy McQuilkin, a RE/Max broker in Exton. "The key is to disclose."

Mary Reish spent much of 2015 in a state of anxiety and sleeplessness over the Mariner East project before she and her husband, Robert, decided to sell their Colonial Drive house in Marchwood and retire to Florida. Reish said the real estate agent disclosed Sunoco's pending easement offer to potential buyers, but instructed Reish to keep her fears to herself.

"When I sold my house, I wasn't allowed to say anything to anybody," said Reish. "The real estate agent was very careful to do all the talking because she knew I would say the wrong thing." The buyers of her house, who paid the Reish's asking price of $330,000 in early 2016, did not respond to an interview request.

Like Reish, Jen Hollywood-Showell and her husband, Charles Showell, were so worried about the pipeline that they decided to move before construction began last year behind their Marchwood house. They disclosed Sunoco's pending offer to potential buyers, and still got the full asking price of $404,900.

The family moved within the Downingtown Area School District, but Hollywood-Showell still visits her old neighborhood, where her former house's backyard has been cleared of trees, and covered with a 50-foot wide swath of timber for construction vehicles.

"My heart aches for those people who stayed because the construction is just awful," she said. "But once that's done and gone, you've got this kind of bomb running through your backyard."

Some buyers, fearful about the long-term safety concerns, are unwilling to pay any price to live near the pipeline. McQuilkin said she represents a buyer who is moving back to the West Chester area from the Midwest and instructed her to steer clear of the Mariner East 2.

"It's influencing his consideration of property in that area," she said.

One area where the project may have had a measurable real estate impact is in the Middletown catchment area of Glenwood Elementary School, which has become the focus of a well-publicized campaign by fearful parents. A valve station is also located about 1,000 feet from the school, which opponents say puts children at undue risk.

Alec Schwartz, a broker with Coldwell Banker Preferred, said that home prices in the Glenwood catchment area have lagged by 7 percent over the last five years compared with prices in the three other elementary schools of the Rose Tree Media school district.

Schwartz said that houses in the Glenwood catchment also took two days longer to sell than houses in other parts of the Rose Tree Media district, a reversal from 2012-2013, when Glenwood homes sold seven days more quickly.

"There's no other reason than the pipeline to think there should be a difference," said Schwartz.

Tom and Diane Smith sold their Middletown house this year near the former Granite Run Mall to get their 8-year-old daughter out of the Glenwood school. "How could I live with sending my child to that school every day?" he said.

Though the Smiths lived well outside the half-mile zone on either side of the pipeline that would be evacuated during an emergency — opponents have dubbed it the "blast zone" — their house did not sell quickly. They knocked down the price from $340,000 to $330,000 and covered the buyer's closing costs, before concluding the sale in March. They moved elsewhere in the Rose Tree Media district, served by another school.

Allison Chabot and her husband, Michael, also decided this year to move away to get their two children out of Glenwood school. But they would be unable to recover their investment in their home on Pennell Road, adjacent to the pipeline path. So they left behind their home of nine years to foreclosure and moved into a rental.

"People are trapped in their homes until the grass grows back and people forget," said Chabot.

Chabot had become an active opponent of the pipeline, but the fight was exhausting and took a toll on her family and her private practice as a clinical psychologist.

Many neighbors were resigned to the inevitability of the pipeline's completion, she said. "They say, 'We didn't want the pipeline, either, but please stop protesting it.' "

A 2016 national report for the Interstate Natural Gas Association of America, a trade association, examined home sales over an eight-year period at five locations in separate states, including Pennsylvania and New Jersey, and concluded that "the presence of pipelines does not affect the value of a home or its insurability."

But the INGAA study looked only at large, federally permitted natural-gas pipelines, some of which had been in service for up to six decades. It also only compared prices of houses next to the pipeline with those of other houses in the same development, a few hundred feet from the pipeline, rather than with a broader market.

"I'm not sure these studies are apples-to-apples comparisons," said Eric Friedman, a resident of the Andover development in Thornbury Township, whose homeowner's association currently is fighting Sunoco's project before the Pennsylvania Supreme Court.

Critics say Mariner East is different from a natural-gas pipeline. The Sunoco pipelines are designed to carry natural-gas liquids, such as propane, ethane and butane, which turn into a heavier-than-air vapor when they leak, and collect near the ground. There are few comparable gas-liquid pipelines in operation, but a 2015 explosion of a similar pipeline in West Virginia scorched a house about 700 feet away.

"How do you put a price on the real estate negativity this is going to bring about?" said Michael Walsh, a mortgage consultant who bought a house in the Andover development in 2015, only to discover later that Sunoco planned to install the pipelines adjacent to his property.

Walsh advises potential buyers to look closely at a seller's disclosure statements, as well as title reports, which may casually mention the presence of easements.

"The buyer needs to take the time to look through a title commitment and then do research to find out what each of those easements entails," he said.