The design and engineering of the extension was very similar to that for the first seawall, but with some modifications based on lessons learned during the 1915 storm.
In cross section, like its predecessor, the wall had a vertical back and a concave to vertical sea-facing front, 5 feet wide at the top and 16 feet at the base.
The top was designed to be set at an elevation of 17 feet above mean low tide. The concrete was reinforced with twisted 1.5 inch square, 10 feet long steel, set 6 inches from the faces of the wall.
The wall would sit on a wider concrete base, which itself was cast over four rows of 9-inch diameter green pine pilings, 30 feet long and a system of wood (later concrete) flat faced planks set beyond the front pilings, a slight change from 1902.
The toe of the wall would be protected with 27 feet of heavy rip rap.
The construction process, while seemingly crude now, was state-of-art engineering used at the time.
It was long on manpower and use of temporary rail systems delivering equipment and the materials to make the concrete on site.
A 250-foot wide right of way for the seawall was prepared, and more than 62,000 cubic yards of sand were excavated.
Tracks were run along the rear of the wall, and the round and sheet pilings were driven by steam hammers.
Flat-faced 26-feet-long wooden (later concrete) sheet pilings were driven in front of the pilings as protection from scour and borers.
A concrete base plate was created using wooden forms and more than 20,000 cubic yards poured over the exposed ends of the round pilings and sheet pilings.
Extensions beyond the width of the base of the wall permitted the use of a wheeled traveler to move steel molds past each other, essentially making the wall construction semi continuous.
Six 30-foot-long specially created foldable steel forms when filled with concrete created the curvilinear shape for the wall and the placement of reinforcing bars.
More than 42,000 cubic yards of cement and almost 550,000 pounds of steel were consumed. In front of the seaward toe, the ground was excavated and filled with more than 36,000 tons of rip rap, including granite blocks of 3 to 5 tons.
While the wall could progress at 60 feet per day, a shortage of labor and materials in 1918 caused delays and the wall construction. It was only opposite the entrance to the Atlantic Hole and about 45 percent finished when the September 1919 hurricane, with a max tide of almost 9 feet, hit.
The original channel draining the hole had been easily closed particularly since land had accreted to its south and the work to take the wall over it had commenced.
Now the scouring around the end of the wall damaged and destroyed equipment, causing the Gulf to reconnect, and created an immense hole and a wide channel across the line of the wall.
Just two months later, in November 1910, a mule-drawn carriage with a father, mother and small daughter and the military head of the garrison was returning along the beach from the military reserve when the carriage overturned in soft sand seaward of the Atlantic Hole. Trapped, an in-rushing tide drowned all but the father.
The wall itself (to its planned end at the first battery and 2860 feet shy of the South Jetty), was completed in 1920. All that remained to be done was to place and shape a 200 foot width of fill behind the wall, to create a sidewalk and brick-paved road and to soil and sod anything not covered.
A study in late 1919 again concerning the east end of Galveston Island, in a nutshell, having recommended in 1913 mot to extend the seawall all the way to the jetty, now proposed to complete the remaining 2,860 feet at a cost estimated at $670,000.
The case presented was that the remaining gap in the seawall defense was concentrating flow during storms, that battery fortifications would be damaged, the South Jetty could be breached and the Galveston channel could be silted up.
This last segment of the easterly extension of the seawall commenced in 1923 and was completed in 1925.
After the seawall structure was complete, there remained the need to support its landward side by elevating the land with fill material. A locomotive crane created a system of levees to hold the fill and gradually elevate it.
The first levee would hold fill extending a large distance from the wall; the second levee would be created on top of the first fill but closer to the wall, etc., gradually stair stepping up.
The fill for the county/city portion of the extension brought the land to specification above seawall height and was effected by dredging from the Gulf side, pumped over the wall using long pipes.
The fill for the government portion from the South Jetty westward was effected using the dredge ship Miller, first positioned in the ship channel then by opening up the South Jetty to allow the dredge and its servicing barge, to create a borrow pit in parallel to the new wall.
That pit, now a good bit wider than the original, is what we call the East End Lagoon.
At a hearing in 1922, the total cost of the first eastern extension was stated as $2,316,000 — with the county and city contributing more than $500,000 each and Maco Stewart deeding his 600 acres.
The cost of the last extension had been estimated at $670,000, so the total was around $3,000,000 — or about $54,990,000 in 2014 — certainly not trivial.
By 1925, the work was finished.
Seeing how the U.S. military were so keen to own and protect so much land at the north East End, that it might be interesting to know just what they used it for.