Costs to upgrade Marine Corps bases to house new aircraft and amphibious vehicles and to support modernization efforts are proving exceedingly expensive, with costs in the hundreds of millions of dollars.

The Senate’s version of the annual defense legislation approved $199,630,000 in funding for construction projects at Camp Pendleton, California, $133,860,000 at Marine Corps Air Station Cherry Point, North Carolina, and $326,845,000 for projects on Guam.

The soaring figures are partially the result of the Corps’ efforts to modernize its force and ongoing construction projects to house nearly 5,000 Marines on Guam.

“We have quite a bit of hangar and utilities work to support the first F-35 squadrons assigned to MCAS Cherry Point,” said Marine spokesman Rex Runyon.

At Camp Pendleton, the Corps is building a new maintenance facility to support Assault Amphibious Vehicles, or AAVs, and the Corps’ latest Amphibious Combat Vehicle, or ACV.

BAE was recently awarded a contract to build the Corps’ new eight-wheeled ACV 1.1 vehicle, which will ultimately replace the legacy AAVs.

The new AAV/ACV facility could cost as high as $49 million, according to the funds approved in the Senate version of defense budget.

The Senate also approved $10 million for a full motion trainer for Marines aboard Camp Pendleton and $71 million for a new mess hall and warehouse.

The Navy also has some projects at the sprawling southern California base to support Landing Craft Air Cushion ships, according to Runyon.

And the Corps is dishing out roughly $51 million for a new complex for 2nd Radio Battalion headquartered at Camp Lejeune, North Carolina. Radio battalions in the Corps provide tactical level signals intelligence and electronic warfare support.

Construction projects are still ongoing on Guam to house nearly 5,000 Marines. About 4,100 of those Marines will eventually be moved off Okinawa, Japan, to new facilities on Guam.

It is part of the Corps’ effort to decentralize Marines in the Pacific in the event of a major conflict with China or a near-peer competitor.

The Senate’s version of the defense bill approved more than $340 million for joint Navy/ Marine and Air Force construction projects on the Island.

Some of those projects include new ordnance storage, dining and housing facilities, and a machine gun range.

According to the Senate’s version, about $141 million was requested for a machine gun range on Guam, but the Senate only authorized $15 million.

Roughly $83 million was set aside for joint Navy and Marine Corps housing projects on the small Pacific island.

The Senate approved its version of the annual defense legislation on June 18.