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Contractors began replacing border fencing along a two-mile stretch of the Organ Pipe Cactus National Monument this week, the first of three projects that will add 30-foot high "bollard" walls along three of Southern Arizona's wildlife refuges.

In photos shared with TucsonSentinel.com, construction vehicles and staged piles of steel beams were sitting along a recently bladed 60-foot-wide stretch of earth on the wildlife refuge near Lukeville, Ariz., about 110 miles southwest of Tucson.

The contractors began at the east end of the pedestrian fence that runs along Organ Pipe Cactus National Monument, and worked west using construction equipment to scrape a roadway along the federally owned easement known as the Roosevelt Reservation.

Environmentalists said the presence of heavy construction equipment elsewhere in the Organ Pipe wildlife refuge was "extremely concerning."

TucsonSentinel.com reported last week that construction was to begin Monday, despite headlines in other news outlets that the work had been "delayed."

The project is a further sign that Trump administration officials are pushing forward on a long-made promise to build a border wall, despite congressional refusal to appropriate the funds, and a lawsuit launched by three environmental groups, including the Tucson-based Center for Biological Diversity.

The border construction work, known as Tucson Sector Project 2, began this week with plans to remove of two miles of existing pedestrian fence.

While officials have often remained closed-mouth about the project, a timeline of the project was included in the government's response to the lawsuit launched by the Center for Biological Diversity, and joined by the Defenders of Wildlife and the Animal Defense Fund on August 6.

Last Tuesday, lawyers for the Trump administration responded and argued that the preliminary injunction "should be denied," and submitted a declaration, written by Paul Enriquez, the director of the Border Wall Program Management Office with U.S. Customs and Border Protection.

Enriquez's description of the projects provides some of the most filled-in details about the planned work, including a timetable of construction in Southern Arizona. Enriquez also said that the agency wants to build a "bridge" over the San Pedro River.

In his declaration, Enriquez described three projects in the "Arizona Project Area," known as Tucson Sector Project 1, 2 and 3.

Tucson Sector Projects 1 and 2 will begin west of Lukeville, southwest of Tucson, while Tucson Sector Project 3 will include chunks of public land just southeast of Sierra Vista, as well as near the Arizona-New Mexico border.

In his declaration, Enriquez wrote that Tucson Sector Project 2 would start this week, and take approximately 45 days as the project begins east of Lukeville, and moves west toward the small Arizona border town. Contractors will install new 30-foot tall "bollard" fencing along the southern edge of the Organ Pipe Cactus monument, and each "bollard" will be a steel post six-inches wide, spaced approximately four-inches apart, and filled with concrete, he said. Along with the bollards, the fence will include a "linear ground detection" system, as well as lighting systems on towers up to 40 feet high.

"The existing vehicle barrier and outmoded pedestrian barrier with the Challenged Project Areas not longer meet Border Patrol's operational needs," he wrote. "They will be replaced with new bollard wall that will be 30-feet tall and includes a linear ground detection system."

Work on the other areas will begin after Project 2, in the Organ Pipe monument, is finished, Enriquez said.

Two other projects were slated to begin this month, but were delayed 45 days because, "the final barrier designs are not yet complete," Enriquez said.

"According to DHS's timeline in their opposition brief to our injunction, no construction activity is supposed to occur until tomorrow," wrote Laiken Jordahl, a spokesman for the Center for Biological Diversity. "And all of that activity should be confined to the two-mile stretch where they plan to replace existing walls east of Lukeville."

Jordahl said that there was also heavy construction machinery near Quitobaquito Spring, a natural spring in Organ Pipe that is home to a few unique species, and that this was "extremely concerning."

"DHS committed to us and the judge that they wouldn't break ground near Quitobaquito until October. But this would be far from the first time they've broken a promise," he said.

On May 15, the Defense Department announced that it had awarded $646,000 to Southwest Valley Constructors based in Albuquerque, New Mexico to design and replace the pedestrian border wall near Lukeville, Ariz., under a project funded by the U.S. Army Corps of Engineers.

That same day, Defense Department officials also announced that BFBC LLC, out of Bozeman, Montana would receive more than $141 million to design and build similar projects in the El Centro Sector near El Centro, California, and in the Yuma Sector, which straddles the Colorado River and includes parts of California and Yuma County.

The project is expected to be completed by Jan. 31, 2020.

Enriquez's statements appear to buttress an argument made by the Center for Biological Diversity, that "there is no current impediment to border wall construction" unless the court intervenes.

In a 46-page document filed on August 6, the groups argued that the proposed construction, "consisting of the erection of impenetrable steel bollard walls reaching 30-feet high and several feet deep" will "result in significant, irreversible impacts to these lands," which serve as "refuges to some of the last remaining populations of endangered species whose continued existence and recovery rely on the freedom of cross-border migration."

CBP would lead the construction efforts and the agency has repeatedly pushed for higher walls along Arizona's borders.

This argument was often repeated last fall and during the early summer when hundreds of people — largely Central American and Mexican families seeking asylum in the U.S. — began walking across the border, often ducking under or climbing over vehicle barriers, or in some cases, digging tunnels in the soft-sand under barriers east of Yuma, Ariz.

The Tucson Sector 262 mile-long border already maintains about 211 miles of "primary" fencing, including both modern pedestrian fencing like the barriers employed in the Nogales-area, officials have pushed hard for taller fencing across the sector's border. Similarly, while the Yuma Sector which has 107 miles of "primary" fencing along 126 miles of border, CBP continues to install newer, 30-foot tall fencing.

In Feb., the executive secretary of the Department of Homeland Security, Christina Bobb, wrote to Defense Department officials and requested their help in 11 separate projects along the U.S.-Mexico border, extending from California's El Centro Sector to the El Paso Sector in Texas. As part of this request, DHS asked the Pentagon for help in building border barriers, as well as roads, lighting systems, and ground sensors that would "alert Border Patrol agents when individuals attempt to damage, destroy, or otherwise harm the barrier."

Just months later, in May, CBP announced it wanted to build 43.6 miles of wall along the southern border of the 330,000-acre Organ Pipe Cactus National Monument, a protected wilderness that has been declared an International Biosphere Reserve by the United Nations, as well as the southern edge of the Cabeza Prieta National Wildlife Refuge west to the Yuma County line.

The Trump administration's plans would effectively split Organ Pipe and Cabeza Prieta from a sister refuge, Mexico's El Pinacate y Gran Desierto de Altar Biosphere Reserve, challenging several endangered species, including the Sonoran pronghorn, desert bighorn sheep and desert tortoises.

CBP would also said it would replace 19.2 miles of fencing in southeastern Arizona, including a section along the San Bernardino National Wildlife Refuge, a 2,369-acre refuge established to protect the wetlands of the Bernardino ciénega, a wetland that serves as a migratory corridor for wildlife moving between the mountain ranges of Mexico and the Rocky Mountains in Arizona and New Mexico.

"Our national parklands and the imperiled animals they safeguard will be protected from Trump’s destructive wall for at least a few more weeks, but they need permanent protection," said Jean Su, an attorney at the Center for Biological Diversity. "It’s ridiculous that it took legal action from us to get accurate information from the government about its plans to bulldoze the borderlands," she said. "But this kind of secrecy is the disturbing result of waiving dozens of environmental laws, including those requiring public notice. We’ll do everything in our power to shine a light on the government’s actions and to stop this disastrous wall."

Enriquez wrote that "no new roads" will be constructed," however, there will be "improvements to existing roads," as well as lighting and possibly cameras, and that all of the construction activity will occur in the 60-foot strip of land along the international border, that is "previously disturbed," Enriquez wrote.

While some construction will begin within days, the agency expects the project to continue through January 2021.

Meanwhile, the remain portions of the two projects will be delayed because "the final barrier designs are not yet complete," Enriquez said.

"Similarly, the designs for the proposed barrier in the San Pedro Project Area have also not been finalized," he said because the agency is continuing to survey "in and around the riverbed" through "mid-to-late September," which will be a "prerequisite to finalization of the contract and designs," Enriquez wrote. The agency said that the new 0.3-mile section across the San Pedro river would include the installation of a bridge over the river beginning in October.

"Given the remaining design work that is left to be done," the Defense Department expects to "conduct no other removal of existing barriers or construction of bollard wall in the Challenge Project Areas before October 1, 2019," he said.

"DoD's contracts for the Challenged Projects have an estimated completion date of January 2021," Enriquez wrote.

Enriquez said that CBP is relying not only on "prior environmental analyses," but that the agency was working on a consultation process that include a request for public input, and the agency sent 100 separate letters to other federal agencies, as well as state, tribal and local agencies.

On July 3, Scott Feldhausen, the district manager for the Bureau of Land Management's Gila District, responded to this request, writing in a letter to CBP that a proposed border wall across the San Pedro would be "an engineering challenge" and could affect how the river flows.

"This extreme flow regime, coupled with the seasonal variability associated with summer monsoons, make installation of permanent, yet permeable, barrier an engineering challenge," Feldhausen wrote.

He also wrote that plans to replace vehicle barriers with bollard walls along 20 miles of border, from the Douglas port of entry to the New Mexico state line could "cause backflow and erosion that could impact both natural resources and the border barrier itself." And, he questioned how these plans would affect five species, including the northern jaguar. "Impermeable barriers may block corridors of movement for these species," he wrote.

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