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The Building Of Bolton Dam
The following history of the Bolton Dam project is adapted from an article by Jerry Chase.
Used with permission.

The idea of harnessing the power of the water at Bolton Falls was not neglected by early Vermonters, but the site was somewhat difficult and situated away from the town of Waterbury. Actual construction of a dam was delayed for many years, as the costs and labor involved were too great for construction of any small sawmill or mill. The possibility of selling or using electric power finally seemed the key to a profitable dam.

The original dam at Bolton Falls was constructed in 1898 and 1899 by the Consolidated Lighting Company, a utility, largely as a response to a monopoly of electric power that existed in Montpelier. Lack of a competitor allowed Vermont Power and Lighting to charge rates that were deemed unacceptable by a young growing insurance company in Montpelier, National Life.

When the Consolidated Lighting Company approached National Life for the financial backing of a new dam at Bolton Falls, the insurance company agreed, realizing this would be a plan that would cut its own power costs, as well as allow it to remain the major investor in a property that could continue to generate both power and money for many years.

Dam building was not a strict engineering science at the time of construction, but many dams had previously been built in New England to harness the water power of streams for various mills, and the principles of construction were well known. A lack of heavy equipment and concrete, and gracious abundance of rocks and forests made the preferred method of building "crib construction." Cutting and squaring large trees, then stacking them in squares like huge matchsticks, the builders would form a "crib," similar to a common corn crib but stronger. The corners of the crib were pinned with a metal rod inserted into drilled holes to keep the beams of the crib from spreading. Loose rock and rubble was then placed in the crib, forming a more or less solid heavy mass.

There were two primary styles of cribbing. The first style tilted the cribs so the tops of the cribs tilted upstream. This style was very stable, as the dammed water pressed the rocks downward as well as downstream. The second style was made with straight vertical cribs. These dams depended on the weight of the stones in the crib and sheer mass of the structure to hold the water back. This second method of construction was less costly and simpler to build, since it used less material and had standard shapes. However, the pressure of the water coming only from one side dictated that the structure had to be both massive and rigid, which is a requirement that loose rocks in a wooden structure find difficult to fulfill unless the structure is oversized or the rocks cemented together with some sort of mortar. It must be understood that concrete was not a common building material, and had indeed only been recently reinvented in England.

In the cases of both styles of crib dams, the waterproofing consisted of a wooden sheathing on the upstream side of the structure. The relatively thin wood layer pressed against the structure and transmitted the pressure to it, while holding back the actual water. Further finishing sheathing like roofing materials were also used to extend the life of the underlying structure. While such dams may seem permanent, they in fact have a finite lifespan unless renewed.

The builders of Bolton Dam elected to use the less expensive vertical cribbing and lay rock into the cribs.

The river was not diverted to construct the dam, but the bottom of the dam has been built as a bridge, with the river allowed to flow underneath it. This does not allow the bottom of the dam to form a contiguous seal with the underlying rock, but causes it to depend heavily on whatever points of contact it has to resist any downstream push. This is practical if the forces can be safely vectored through those supports to solid ground and the structure on top is rigid.

The structure was a relatively thin dam, narrower than it was be tall. Also, there was no attempt to use the timbers in such a way as to transfer the downstream thrust of the river to the rock canyon or base of the dam. There is also no attempt to form triangular sections of cribbing, which would have had much greater lateral strength. The structural integrity of this structure was based on whatever was used to pin the cribs together and the tight fit of the rocks. Without the rocks, the rectangular cribs could be easily deformed.

The first tragedy connected with the dam is related here as told by Brian Lindner:

On February 18, 1899, Charles Doherty shot Fred Murphy in Waterbury at the J.E. Pixley farm near Bolton Falls. Both men were workers on the project to build a hydro-electric dam across the Winooski River. It had been well known that Doherty and Murphy had been in conflict for several weeks prior to the shooting. It would appear that Julia Rock’s relationship with Murphy was at least one of the major causes of Doherty’s intense dislike of Murphy.

On the day of the shooting, Doherty made it obvious that he was carrying a gun. He made threatening statements both to Murphy and others at the job site. When both men returned to the J.E. Pixley boarding house where several dam workers lived, they became embroiled in an argument. It would appear that Doherty taunted Murphy to meet him in the adjacent barn to settle matters.

According to witnesses, as Murphy followed, Doherty suddenly spun around. Murphy tried to duck and move to the right but was hit by a single .32 caliber gunshot wound in the left side. Witnesses stated that the gun was so close as to have the muzzle flash touch Murphy’s clothing. Murphy was helped inside and operated on that evening by Dr. Henry Janes and Dr. D.D. Grout as they removed the bullet. Murphy was in extreme pain despite the nursing efforts of Julia Rock who tended to him until March 13, when he was taken to the Mary Fletcher Hospital in Burlington. Murphy was unable to eat and lost up to 25% of his body weight. On April 1, 1899 he died in the hospital. Upon autopsy, Dr. Janes and others concluded that the cause of death was infection from the gunshot wound.

After shooting Murphy, Doherty boasted of his deed to fellow workers then jumped a southbound train at the North Duxbury station. Later that evening, he was spotted walking along the tracks in Montpelier Junction. When summoned to stop by policemen, he ran. He soon tripped and was immediately captured. The officers found a .32 caliber pistol in his possession.

Within days, Doherty’s initial hearing was held in Waterbury at “the old high school.” (Probably in the building that now stands at 6 Elm Street but which once stood next to the Congregational Church.) When Sheriff Graves brought Doherty to the first day of the hearing, their sleigh was met by Randall Blodgett and a small mob, apparently at the top of Bank Hill. Blodgett attempted to take Doherty at gunpoint with the intention of having a mob lynching. While the Sheriff stood his ground, Doherty’s attorney jumped forward and grabbed Blodgett’s gun as Doherty huddled in terror behind the Sheriff.

After Murphy died in April, Doherty was charged with murder. His trial was held at the end of November and he was convicted of first degree murder.

In 1956, R.L. Duffus published a book entitled, The Waterbury Record in which he gives a largely fictitious version of this case.

As bad as the murder of a construction worker was, it was generally expected that a few men would be injured or killed in any large construction project, and work continued. As another side note, the Irish names above should not be taken as an indicator that the dam was built only with outside Irish labor. The heavy work at the dam was done with the substantial help of Italian laborers, and local citizens were also employed on the project.

When the cribbing had reached full height, the dam was sealed and filled with water. I have not discovered the exact method used to seal the dam, but I suspect that sheathing was applied to the upstream side and rocks or rubble used to block off the bulk of the flow underneath the dam. Skip Flanders has informed me that the original hemlock planking used in the dam came from the nearby Preston Farm.

It was at this time that there was a near disaster, and an event that must have forever haunted the designer of the dam. The pressure of the water caused the cribbing to shift downstream, with part of it reportedly bowing eight feet downstream, and the top center of the structure sagging three feet as the rocks and the cribbing resettled.

I believe a lot of the movement was caused by the rocks within the cribs being placed flat, as one would build a stone wall. This created a structure somewhat like a stack of coins, where side slippage is easy. Another factor may have been the type of rock used and its condition. If local fieldstone from surrounding stone walls was used, as was common practice, the rock fill could have been covered with a layer of moss and lichen that acted as a lubricant when it was turned into mush by the pressure and the moisture within the cribs. The narrowness of the dam was the third factor in the slippage. A wider, more conservative dam would have better resisted forces wanting to create movement through through the mass of the structure.

Near panic must have reigned as the structure began to bow. An eight foot bow in a structure thirty feet deep substantially weakens it, and instead of the mass of stones holding back the river, a lot of the water pressure was having to be restrained by tension on the pins in the wooden cribbing. Continued stress on those pins and the inevitable rotting of the wood would cause the dam to eventually fail.

It was decided that the solution to the problem would be to construct a masonry dam just downstream of the damaged structure. I am not sure of the thought process involved, but I imagine the idea was to create the masonry wall (at great expense) and then backfill between it and the existing cribbing to transfer some of the load to the masonry. Adding more cribbing and stone might have been an alternate less expensive solution, but the thought of attempting to tie into that cribbing already under tremendous stress must have seemed too dangerous.

The cost overruns of this structure were so great that the National Life Insurance Company was teetering on the edge of bankruptcy. It is said that if one of the major policies had demanded a payout at the time of the dam's completion, it would have destroyed the company completely.

In 1906, the power plant was modified and the owners increased the power output of the dam by 1,200 Kilowatts, building a new concrete turbine housing, adding an 1800 horsepower Allis Chalmers water wheel, a 1,200 Kw General Electric generator, and utilizing the sluiceways to feed a penstock to the new turbine.

There were changes of ownership in the early power companies. Consolodated Power had leased the Vermont Power and Lighting Company by 1910. Ownership of the dam was then transferred to the Barre and Montpelier Light and Power Company in 1913. One of the first things the new owners did was to add a concrete toe on the downstream face of the dam. This area of the masonry dam would have been under the greatest stress, especially if the original cribbing shifted more, or began to decay. Concrete construction was constantly gaining favor and the new toe was a prudent addition to the dam.

In January 1927, the dam was sold again, this time to the Peoples Hydroelectric Vermont Corporation, a company which changed its corporate name to Green Mountain Power the following year, probably in direct response to the negative connotation of water power after events in the fall. In November of 1927, Vermont had a true watershed event that changed the course of local history. Repeated rains in the fall saturated the ground until it could hold no water, and then the heavens opened in ernest, starting on November 2^nd, eventually creating a hundred year flood.

The Waterbury Duxbury area was perhaps the area in Vermont hardest hit by the flood of '27. In addition to the tremendous flow of the Winooski at flood stage, Allen's Rock at Bolton acted as a dam far greater than the puny crib structure, slowing the flow and allowing water to pile up further upstream. In Waterbury, the river backed up quickly. Early on in the flood, water rose a foot in fifteen minutes continuously for the space of two hours. The entire railroad station was eventually submerged and water rose to near the top of Bank Hill, almost reaching Stowe Street. At full crest, the Winooski was more than a mile wide in Waterbury, creating a lake with islands of the top floors of the Vermont State Hospital and the tops of some houses not washed away by the floodwaters.

The scene at the dam must have been positively frightening. Estimating the height of the flood waters flowing over the dam is difficult. Certainly ten to fifteen feet would be a conservative possibility. The destruction in Waterbury could have been much worse though, had it not been for the railroad cut to the south of the dam, which acted as a relief spillway of giant proportions.

When the Waterbury Dam was completed just upstream, on a tributary of the Winooski known alternately as the "Little River" to people of Waterbury and the "Waterbury River" to people of Stowe, the minimal power output of the dam didn't seem to justify continued operation.

The Waterbury dam opened officially on October 29, 1938, although according to Ralph Nading Hill the power generating capacities of that dam were not yet built as of 1949, probably both for the reasons described below and because of lack of funds during the late 1930s. Be that as it may, the Bolton Falls dam was decommissioned in 1938 and equipment removed. 1938 must also be remembered as the year of the Hurricane of '38 which caused great damage in Vermont. It is possible that the costs of continued repair and maintenance of the power facilities were too great for the little amount of power generated at the oft repaired dam site.