The Chisana Story

[Steve Herschbach]

One thing I always found fascinating at Chisana was the effort expended to bring water to bench locations - gold bearing areas far above the current stream area. The terrain is steep, and the bedrock is fractured to great depth. This made ditches a poor solutions for much of the area, and wooden boxes or "flumes" had to be constructed to carry water to the desired mining areas.

Just getting the lumber to the site was a major undertaking. The gold bearing creeks are well above treeline. That being the case the lumber was whipsawed in the valley below then pulled by horses to the valleys above. More impressive was the engineering feats involved. The flume would start far upstream at creek level and then follow a more gentle grade than the creek itself, eventually bringing water miles downstream and hundreds of feet above the current stream level. In the process gullies were bridged and the entire structure built across cliff faces. Most of the old flume system is gone or in serious disrepair, but sections remain to tell the tale.

Click on images for larger views....

View down lower Little Eldorado Creek - flume high on hill in distance

Closer look at flume above mouth of Little Eldorado Creek

And closer yet...

Upper Bonanza view of flume system - much of the wood has been scavenged over the years

Flume crossing cliff areas

Detail of flume construction

Flume winding around the terrain

The old flume system close up

To be continued...

[Jim_Alaska]

You are right Steve, the effort those old timers went to is nothing short of unbelievable. In Alaska's Interior where I lived I found a lot of evidence of mining in the old days. Not much for flumes like you pictured, but lots of old shafts, some as deep and 100 feet. Old wooden sluice boxes are common. And old boilers for thawing perma-frost and frozen winter ground.

I found a lot of this kind of evidence because I was a trapper in winter and had access to ground that was inaccessible in summer. Some of those old boilers were huge. And just thinking about how they got them into those remote locations made me weak and tired.

Of course some of that heavy stuff was hauled in by sled and mules/horses in winter along the frozen rivers.

Many times old mining areas could be discovered by extensive old tree cutting, with only the stumps remaining. They had to cut a lot of trees for boilers and heating cabins in winter, not to mention building of cabins and sluice boxes. 

At the turn of the century miners started using huge riveted pipe to bring water from distant locations. This was in place of wooden flumes and a lot of it was done by bigger mining companies. Some of the large companies around Fairbanks brought water from miles away like this for running the bucket line dredges. Some of that riveted pipe was so large a man could stand up in it stooped over a bit.

That reminds me, I think I have a picture of that pipe somewhere. Will post it if I can find it.

[flakmagnet]

That Alaskan flume building is crazy. I thought the ditches they built in the Sierra's for doing the same thing were pretty incredible...I take it back.

[WesD]

Flak, our California boys were no joke either!  I dont know what these guys were eating  to work that hard.

[jrbeatty]

We Aussies weren't shirkers either, Wes. 

The giant water flume Lightning creek, Omeo, VIC

[Jim_Alaska]

Wow, that is just amazing JR.

[flakmagnet]

Hi Wes, Yes I agree the 49'ers were beyond industrious. As you know just to drive along sections of rivers like the Yuba where they flumed long sections of it, took every rock out and stacked them beside on the banks so they could break open the cracks on the bottom, is eye-opening. It is hard to comprehend some of the work gold hunters everywhere put in.

[Steve Herschbach]

From Placer Mining Methods and Costs in Alaska by Norman L. Wimmler, U.S. Bureau of Mines, 1927

FLUMES AND SIPHONS

Flumes and sometimes pipes are used for conducting water across ravines or places below the grade line of the ditch, along the face of vertical cliffs, over ground containing shattered or porous material productive of large seepage and absorption losses, or over ground difficult and costly to excavate. Most ditches encounter some of these conditions and ordinarily some flume must be constructed. Many miles of flume have been built in Alaska, but because the cost of construction is generally high and they are difficult to maintain, flumes should be used as little as possible, especially where ditching can be done or where pipe is permissible.

Flumes are less permanent than ditches, for they are subject to exceptional deterioration as the waterway is not in use for the greater part of the year. Sand and gravel in the water cause deep scouring of the lining boards when in use, and during the winter the action of the ice and frost loosens and warps the boards. Snow and rock slides, floods, forest fires, and the weight of the deep snow may all cause damage. Where flumes are constructed over frozen ground special precautions are necessary to protect the ground from thawing; otherwise the foundations may settle, open the joints, loosen the boards, and make the flume break to pieces. Thawed ground expands on freezing, raising the flume and throwing it out of line and grade. On subsequent thawing, the flume will rarely return to its original position and after several of these successive periods will be so out of position as to be useless.

SUCCESSFUL FLUME CONSTRUCTION

Successful flumes have been built over frozen ground where the heavy sod covering is still intact by placing two heavy log stringers side by side on the sod parallel to the proposed flume; on these are placed the sills upon which the flume is constructed. Where there is no sod, the frozen ground is covered with a thick blanket of sod to keep in the frost. A thick covering of clay has also been used, but it is not a permanent protection. Satisfactory foundations have also been made by digging shallow holes, filling them with gravel, and placing on top a wide plank or timber to distribute the load. A notably successful flume over frozen ground was built on the Miocene ditch.²²

This flume is 1,100 feet long and has a width of 8 feet and a depth of 28 inches. It was constructed in 1901, and until 1906 or 1907 it retained practically perfect alignment, both horizontal and vertical. No extensive repairs were necessary on it until 1909. In putting in the foundations, trenches were dug 3 or 4 feet in the frozen ground, which was practically all ice. A sill was laid in the bottom of the trench and the uprights fastened to the sill. The excavated material was then replaced in the trenches and allowed to freeze again into its original condition. Sod was carefully placed over the trench, the

uprights were then sawed off to grade, and the flume constructed on them. Even with all these precautions, however, at the end of about eight years the flume was in such bad shape that extensive repairs had to be made.

The grade to be given a flume is generally governed by the topography. Although increasing the grade also increases the velocity of the water and thereby permits use of a small flume at less expense, this practice is not the rule in Alaska. Most Alaska flumes are set on the same grade as the ditch or at a slightly increased grade. There are a few places where the flume grade is twice that of the ditch.

The iron fluming which in recent years has been placed on the market has many advantages over the ordinary board flume and should be considered. in districts where lumber is expensive and long life with low maintenance is desired. Figure 8 shows a board flume in the Rampart district.

 

[Steve Herschbach]

I visited Chisana and Bonanza Creek specifically in the 1990's but my records are pretty thin for this time period. The White's Goldmaster II revolutionized metal detecting in Alaska with its hot 50 kHz circuit. Alaska is not the land of large gold nuggets like Australia. In fact, large nuggets are very rare in Alaska, with the bulk of the gold produced being very fine gold as found by the bucket line dredge fleets in the state. The generally small gold size, and relatively low ground mineralization means hot VLF detectors work well for Alaskan prospecting. The Goldmaster series were the first really successful nugget detectors in Alaska, followed by the Fisher Gold Bug 2. As you can see below, my small nugget finds really took off with the Goldmaster!

Every few years I would take the latest, newest model of metal detector to Chisana and find some more gold. Here are a few photos from the 1990's....

Steve with early White's Goldmaster hunting the bench workings at Bonanza Creek

Bonanza gold found...

And more Bonanza bench gold....

Put it in a pile with the fines and better light....

Steve at Chisana with Minelab XT17000 metal detector

To be continued....

[IdahoPeg]

That is some serious gold on that Bonanza bench!?