Construction of a secondary border wall replacement has begun in San Diego, according to U.S. Customs and Border Protection.

The secondary wall project will replace up to 14 miles of a steel-mesh barrier with a 30-foot tall steel bollard wall, CBP announced in a news release Tuesday.

"This project is directly north to the San Diego primary fence replacement project that is currently under construction funded with FY 2017 funding," the release said.

The first panels of the wall went into place Monday, according to officials. The steel bollards will replace a decade-old layer of barrier that can be easily breached using battery-operated saws, according to KSWB-TV.

Texas-based SLSCO, Ltd., was awarded the $101 million contract in December. The contract includes options for an additional $30 million.

There are two layers of barriers that run parallel along the U.S.-Mexico border in San Diego.

Did California try to block the construction?

The state of California, along with some environmental groups, attempted to stop the construction by filing a lawsuit against the Trump administration for waiving environmental reviews prior to construction.

Last week, a federal appeals court upheld a previous district court judge's decision to allow the construction to move forward, The Hill reported.

The court ruled that the U.S. Department of Homeland Security has broad authority under the Immigration Reform and Immigrant Responsibility Act of 1996 to construct and replace the border barriers near San Diego, as well as another section near Calexico, Calif.

What about the primary wall project?

The primary wall project is almost completed in San Diego. It has also been constructed with steel bollards of up to 30-feet tall and it also runs about 14 miles along the border.

The previous barrier, made of corrugated steel matting used to create temporary runways for the military, was built in the early 1990s, KSWB reported.

What else?

On Friday, President Donald Trump declared a national emergency at the U.S.-Mexico border to circumvent Congress and redirect billions of dollars to secure funding for a border wall.

The San Diego project is not connected to the emergency declaration.

The president's decision came after Congress failed to secure the full $5.7 billion requested for the border wall in its spending bill. The bill passed with $1.375 billion earmarked for border security.

Later this month, construction on a 14-mile border wall extension is expected to begin in the Rio Grande Valley in Texas.

