The two large, pale red, landslide scars on a 100-foot hillside overlooking the Ohio River in Moon are bad enough to look at.

But for David Bundy, the developer of 68 luxury townhouses off Stoops Ferry Road on top of the hill, they're a daily reminder of his own potentially hazardous mistake.

"I don't argue with anyone. It was something I created," said Mr. Bundy, whose family-run company, Prestige Homes Inc., of Crescent, is building the Staunton Heights townhouse development on the hill.

He admits it was his decision to dump fill in order to extend the back yards of the riverfront townhouses, which cost from $350,000 to $450,000 each.

Over the winter, snow and rain added weight to the fill and, because it sat on a hillside of red clay known as "Pittsburgh red beds," it began to slide behind four of the townhouses, carrying dirt, rock and mature trees more than 40 feet tall down to the edge of the CSX railroad tracks.

The townhouses, with their deeply anchored foundations, are secure, officials believe.

Mr. Bundy admits he dumped the fill without consulting his project engineer and in violation of the plan the township approved for the site.

"I did not think four to five feet [of additional back yard] would be that big of a problem," Mr. Bundy said. "There's no question, it's been a nightmare for us. I've lost sleep because of this."

Mr. Bundy, who has spent the past four months trying to correct the problem, has built a concrete wall on the steep hillside. He hopes to be allowed to finish work on the area near the top of the hill in the next month, after additional testing and a plan to correct the problem is approved by the township.

"That scar will be there for decades, if not centuries," said Roy Kraynyk, executive director of the Allegheny Land Trust, a conservation group that led a hillside development study for Pittsburgh two years ago. "I just hope municipalities see this and do better to protect slopes over 25 percent [grade]."

During the past several months, the denuded 50- and 100-foot-wide swaths of hillside drew the attention of officials from Moon, the state Department of Environmental Protection, a local environmental group and CSX.

Such slides are exactly what Moon officials were trying to prevent when they passed hillside development restrictions four years ago. The restrictions, considered among the toughest in the county by Allegheny County officials, limit development on slopes steeper than a 15 percent grade and require additional engineering work to build on such areas.

The riverfront Staunton Heights property was not affected by the township's slope development restrictions because the project plans were filed in 2001, a year before the restrictions were adopted, said Lora Dombrowski, the township's assistant planning director. But the riverfront houses might not have been affected anyway, she said, because they sit on a relatively flat ridge on the hillside.

But even if they had, Mr. Kraynyk said, the ordinance falls short because it fails to limit development near slopes, such as the hillside below Staunton Heights, and does not prevent developers from taking down trees on hillsides, two factors Mr. Kraynyk believes played a role in the landslides.

"The developer may not have been on steep slopes," Mr. Kraynyk said, "but he may have disturbed the steep slopes and that led to the slides."

The township initially ordered all work to stop on the entire site, but it has withdrawn the order. It has banned any new building permits for the development until geological tests are finished and a remediation plan for the hillside is approved.

"This slide brings home the point that we have these regulations for a reason," said Alex Ropelewski, chairman of the board of supervisors, which has heard complaints recently about the Staunton Heights landslides.

"But unless you have someone on site 24 hours a day, you're just not going to notice" a developer placing fill outside approved boundaries, he said. "You have to place trust in the developer to some degree."

The state Department of Environmental Protection and the Allegheny County Conservation District monitored the landslide cleanup to make sure it didn't affect the river. Neither imposed any penalties on Mr. Bundy.

The township could have fined Mr. Bundy, but it didn't, said Scott Brilhart, the township's planning director.

"If we issued a fine, it wouldn't have helped the property owner," he said. "I don't think they'd do that with any other homes. They've learned a lesson there."

It took two mistakes for that lesson to be learned.

When some of the new homeowners said last year that they wanted slightly bigger back yards on the edge of the hill, "I thought it was a no-brainer; I'll just put some more fill behind the homes," Mr. Bundy said.

After Mr. Bundy noticed in August that the fill was starting to move, crews began to remove some of it, placing it in a vacant lot along the hillside. The pile of fill eventually created the same problem as the original site, and it caused the second, smaller landslide.

Mr. Bundy told the owners of the four houses immediately above the bigger landslide about his mistake and two of them say they're pleased with Mr. Bundy's response.

"I've got to tell you, from our point of view, we can't be more pleased with how quick they got in there and started fixing the problem," said Craig Koerpel, who bought one of the townhouses immediately above the larger slide area because he liked the river view. "I don't think these guys deserve a bad rap."

The township also is pleased with Mr. Bundy's response, even as it begins reviewing an addition to the Staunton Heights development, which would add even more houses along the hillside overlooking the river.

"Because of the landslide," Mr. Brilhart said, "I think there will be some closer scrutiny when [the additional development] is reviewed. We don't want this to happen again."