Washington (CNN) The Defense Department is scouting sites along the US-Mexico border to erect new physical barriers, according to two department officials.

Small teams of engineers and experts, comprised of about 10 personnel, are on the ground in Yuma, Arizona, and the New Mexico part of the El Paso sector, which also includes Texas, looking at sites, the officials said.

Jay Field, a spokesperson for the US Army Corps of Engineers, later confirmed the teams' presence on the ground, telling CNN that the eventual plan is to install 11 miles of fencing at Yuma and 46 miles at El Paso.

Each assessment should take about seven days. Formal engineering surveys are expected to follow in late April following the award of contracts to builders, which is expected to happen in mid-April.

Actual construction could begin by late May, depending on whether the Department of Homeland Security issues environmental waivers, which is sometimes done to expedite construction. The new construction will be funded by the $1 billion recently transferred by the Pentagon.

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