ALAMO -- Neighbors whose fences straddle county land at the Iron Horse Trail may find they have to remove them, pay rent or buy insurance for the right. Contra Costa County officials are taking action to deal with property owners who have built bridges, fences, and other structures on county property along the trail.

Carrie Ricci, the county's manager for the Iron Horse Corridor, said encroachments by homeowners into an easement where a high-pressure jet fuel pipeline runs underground conflict with state fire marshal regulations and are a safety concern for the county and pipeline owner Kinder Morgan Energy Partners.

Ricci and Kinder Morgan representatives attended an Alamo Municipal Advisory Committee meeting Tuesday to discuss the issue and answer questions from the committee and about 20 residents who attended.

Over the next few months, Ricci said county officials will contact homeowners who are encroaching into the trail corridor. She said there are about 50 to 75 homes in Alamo where structures have been built in the corridor on county property, with about 25 of encroaching onto the Kinder Morgan pipeline easement.

Encroachments onto the pipeline easement will have to be removed, she said. Those encroaching onto county property away from the pipeline will be dealt with on a case-by-case basis. Owners could be asked to remove the encroachments or pay a fee and buy insurance for using county property.

For those who don't comply, the county could begin abatement proceedings that could result in the county removing the encroachment at the homeowner's expense, she said.

The county bought the Iron Horse Corridor from the Southern Pacific Railroad Company in the 1980s. It is about 19 miles long and stretches from Concord to the Alameda County line. Today, it is known for its popular paved trail but it is also used by a number of utilities, including Kinder Morgan, whose pipeline carries gas, diesel and jet fuel from Concord to a terminal serving Mineta San Jose International Airport.

Questions about the age and fragility of the pipeline were raised during the meeting.

Murphy said the pipeline was built in 1965 and operates under a pressure of 1,300 pounds per square inch. "If we think the pipeline is fragile in any area, we dig it up and remove it," he said.

The Alamo committee asked the county to put permanent survey markers on the boundary of its property and for a list of properties deemed to be encroaching.

In 2010, a 90-foot oak tree just south of La Serena Avenue and parallel to the Iron Horse Trail was removed because it was thought to be a danger to the pipeline.

In 2004, five workers were killed and four injured when the pipeline exploded in Walnut Creek after being punctured by a backhoe.

Contact Jason Sweeney at 925-847-2123. Follow him at Twitter.com/Jason_Sweeney.