The eight border-wall prototypes President Donald Trump inspected during a visit to California in March are going to be torn down to make way for a second barrier separating California and Mexico, the U.S. Department of Customs and Border Protection said Friday.

Construction crews have replaced one layer of fencing along a 14-mile (23-kilometer) stretch of the border separating Mexico and California. Crews recently started work on replacing and extending secondary fence as well.

Border Patrol Agent Theron Francisco said Friday it isn't clear when the prototypes will come down. But he added money has already been set aside for their removal.

The San Diego Union-Tribune reported Friday they cost between $300,000 and $500,000 apiece to build.

"There is money already allocated to either take them down or build infrastructure around them. But the decision has been made at the national level to take them down, and the secondary replacement project will take their place," Francisco said.

Trump declared an emergency last week to shift billions of dollars to fund border wall construction.

The Democrat-controlled House of Representatives is set to vote next week on whether to block that declaration. Some members of the Republican-controlled Senate have indicated it could pass that body as well.

If it does, Trump has promised to veto the measure.