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World War II Era Bunker To Be Demolished On New Navy Coastal Campus

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Posted: Friday, January 22, 2016 3:10 pm

Sitting high on a ridge overlooking the Pacific Ocean, located along the northern-most border of Imperial Beach is a concrete bunker that measures 300 feet wide, 600 feet long and 40 feet tall, made entirely of what is now well-aged concrete and scheduled for demolition. The genesis of this story occurred four months ago during an interview undertaken with Navy personnel regarding construction of the new $1 billion Coastal Campus on the site of the existing Silver Strand Training Complex. I was immediately intrigued by the presence of a World War II relic of that enormous size.

The Coastal Campus will be comprised of 24 projects totaling 1.5 million square feet and will eventually house 3,300 Naval Special Warfare Command (NSWC) personnel currently stationed at the Naval Amphibious Base. Coastal Campus Program Manager Jason Ashman said during our session that of the 548 acres on the current complex, only 167 acres are included in the project. Right smack dab in the middle of the project area is the concrete bunker, which is made of steel reinforced concrete, 13 to 17 feet thick, with an earthen covering 6-15 feet thick. Steel rebar is set into the concrete about every foot and additional stone is included for strength. As an added bonus, concrete gets harder the longer it sits.

For the first several years my family lived in Coronado, we lived in the Coronado Cays for a dozen years. Part of my subsequent fascination with the bunkers is that until three months ago, I didn’t know they existed, even though I drove past the area a couple of thousand times.

Some backstory is needed at this point for reference. The current training complex began its life in the 1920’s as the Navy Radio Compass Station. From 1942-1947 the U.S. Army took over the station which was located in what was then called Coronado Heights, and renamed the facility Fort Emory. A small battery of artillery was installed at Fort Emory, which was under the command of personnel at Fort Rosecrans. Two much smaller bunkers not in the construction zone will remain intact.

Construction on the larger bunker was completed by 1944 Had they been installed, the firepower would come from guns which weighed 146 tons each, were 69 feet long and could fire a 2,340 pound shell a distance of 30 miles. The effective range of the guns, similar to those found on Navy battleships, would be from south of Tijuana to Carlsbad. Imagine seeing an artillery shell the size of a Volkswagen Beetle flying through the air. 

Other bunker details as outlined by Ashman included, “On the eastern side there are three regularly-spaced entryways. The northern and southern doors provided access for equipment and ammunition while the central entry was primarily a personnel door. On the western side, facing the ocean, the two gun placements were located 500 feet apart. Each is a large poured concrete surface and the retaining wall is about 100 feet long and 40 feet high. On the surface, the guns themselves measured about 24 feet in diameter, but were surrounded by another 21 feet of concrete on each side. Each gun mount has a solid concrete conical deflector awning or casemate that extends over the gun.”

Fortunately, Naval Base Coronado Public Affairs Officer Sandra DeMunnik recognized my growing obsession with the subject and assembled a Dream Team of experts to take me on a tour of the bunker. Our travel squad included Coastal Campus Deputy Program Manager Bruce Shaffer, Historian and Cultural Resources Manager Alex Bethke and Naval Base Coronado Environmental Director Jason Golumbfskie-Jones and DeMunnik. 

To provide some additional perspective to the project at hand, Bethke estimated that 36 installations, with 150 total structures housing 16-inch guns were constructed throughout the world. When asked about the military strategy behind the bunker Bethke replied, “There was a huge military presence in San Diego (during World War II) and there was also a huge aircraft manufacturing presence which was consolidated around the airport. There definitely was a threat of San Diego being a target. You had to defend the facilities here.” Shaffer added, “There was a lot of investment in the project in time and effort. Four guns here (the two planned 16-inch guns and two six-inch guns that were actually installed) took the place of five guns at Battery Whistler at Ft. Rosecrans. It took fewer personnel, worked with greater efficiency and overall had a greater capability to defend the harbor. It absolutely made sense.”

In short, these bunkers were built to last. In the 1980’s, the attempted demolition of the Deer Island coastal bunker installation in the Boston area failed. In recent years the Coastal Campus bunker has been designated ‘Building 99’ by the U.S. Navy and was re-purposed as an instruction area for SEAL personnel. During our tour, SEALs were removing chairs, lockers and exercise equipment from the bunker in preparation for the demolition.

To me, the concepts of environmental protection and bunker demolition would seem to be mutually exclusive. Which makes the job of Jason Golumbfskie-Jones particularly challenging, as he explained. “During the whole planning phase, it was required that we take a step back and look at the environmental consequences. It’s our responsibility to follow all federal and state regulations and we have to make sure that our contractors are compliant with all of the regulations. We have looked at how and where people can build or demolish during the different breeding seasons. On the south end of the campus we have 100 acres of vernal pools where we won’t be developing, where there are fairy shrimp, snowy plover and least tern.”

And as an added feature, the project will attempt to remove ice plant, an invasive plant that has been growing in the area. Golumbfskie-Jones also explained the lack of trees on the campus. “Trees are a habitat for Raptors who attack and eat the snowy plover and least tern. And we are also doing a lot with storm water mitigation. The buildings will be designed to retain storm water so that it can be re-used or until the soil can retain the water.”

Which leads to the question of how to demolish an enormous amount of steel-reinforced concrete, much of it covered in earth, that has now been curing and getting stronger for roughly 71 years? Enter Baldi Brothers Construction which is headquartered in Beaumont. Golumbfskie-Jones said the demolition is expected to take a full year to complete and will start on the north end of the bunker and work south. One of the primary pieces of equipment for the job was described as, “North America’s largest hammer.”

DeMunnik said, “The hammer hits points in the concrete and taps it to create cracks. Then a calk is inserted into the crack which was created with the hammer and expands the crack. That makes the structure weaker and then they continue tapping with the hammer. Once you get a little bit of a break in the concrete, you expand the joints.”

Golumbfskie-Jones added, “One of the benefits of using the hammer versus explosives is dust and sound mitigation. There will be minimal noise, which allows us to be good neighbors to the Cays and Imperial Beach residents, with no explosions. A trench will be dug which will stop noise and vibrations from traveling through the ground. The trench acts as a dampener and dissipates everything.”

In a follow-up E-mail, DeMunnik specifically addressed the heavy equipment that would be employed for the demolition. “There will be large excavators with multiple attachments, such as hammers, grapples, shears and pulverizers. The make and models will vary, but include the Hitachi 1800 series, the Caterpillar 5110 and Volvo 92,000 pound excavators with miscellaneous attachments.”

Now what do you do with tons of rebar-enforced concrete? Deputy Program Manager Shaffer had the answer. “We actually have a stock pile area for the reusable concrete and the reusable soil, which can be used for construction base or on some foundation areas on campus where we do berming. We can use some of the concrete as riprap and for bank stabilization material, draining and storm water control.” Golumbfskie-Jones said, “The Navy’s goal is waste minimization.”

Historian Bethke has also been kept busy as the start of demolition looms large. “It’s important from an historical perspective that we have good documentation on the site. This is not going to disappear in the vapor. We will fully document the bunker in narrative and by photos. We will also have some demolition photos as well. We’ve documented the bunker to the best of our ability, which includes the Ft. Emory Historic District. We documented the Wullenweber Antenna Array as part of the Coastal Campus site. We did a digital model with laser scanning to create a mini-documentary that will be sent out to libraries soon and we will make it a point to include the Coronado and Imperial Beach Libraries and send a copy to the Coronado Historical Association. We want to make history accessible to the public and we are trying to do that the best way we can.”

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