BOULDER’S WATERWORKS

producing 5,000 kilowatts (KW) of power, for a total capacity of 10,000 KW.
Building materials and supplies for the construction of the Boulder Hydro Plant also were
transported by the narrow-gauge railroad. Steel pipe sections, generators, shafts, turbines
and other necessary pieces of equipment were delivered by train to Orodell. The equipment
then was unloaded from the rail cars and transferred to wagons. The largest wagons,
capable of carrying turbines weighing 36,000 pounds, were pulled by 14-and-16-horse
teams. 91
Equipment then was hauled to a construction camp known as Headquarters Camp that
was established at the Hydro Plant site. The small village included living quarters, offices,
a stable, a blacksmith shop, and a dining hall––all fed with running water through a piped
water system diverting from Boulder Creek.
During construction, a tramway was built from Headquarters Camp to carry materials
up the steep mountainside to the site of Kossler Reservoir, on the ridgeline of Flagstaff
Mountain 1,828 feet above the Hydro Plant. The site was located in a natural depression
which required dams no more than 18 feet high. When completed, Kossler Reservoir was
connected to the Boulder Canyon Hydro Plant by a 9,647-foot-steel penstock, still in use
today. The upper section of the penstock is 50 inches in diameter and tapers to 44 inches. 92
The huge drop between Kossler Reservoir and the plant created the highest head of any
hydroelectric plant in the country, at the time.
One difficult construction problem was caused by the tremendous water pressure developed
due to the large elevation change in the penstock. The penstock was constructed
from steel plates held together with two-inch rivets, but it was not enough to seal the
joints against pressures reaching 840 pounds per square inch. A welder skilled in the new
process of acetylene welding was brought in to secure the rivets and joints, but the joints
cracked when they cooled. After experimentation, the crews discovered that hitting the
rivets with a ball peen hammer while still hot from welding prevented the cracking and
stopped the leaks. "Ball peen welding" was thereby invented. 93
As work continued on the dam at Barker Reservoir and also at the plant, the Barker Gravity
Line––a 36-inch diameter, reinforced-concrete pipeline––was built between Barker Dam
and Kossler Reservoir on Flagstaff Mountain. Most of the Barker Gravity Line was constructed
out of concrete pipe sections that were two feet in length to accommodate all of
the twists and turns the pipeline had to make through the rugged terrain. The pipe sections
were cast in place in a meadow on Magnolia Hill, then transported up the mountain
for placement. 94 It was estimated that the Gravity Line would cost $550,000 to build. 95
By October 1909, the three dams that formed Kossler Reservoir and the 11.7-mile Gravity
Line were completed, and the first water flowed through the pipeline to Kossler on September
1, 1909. 96
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