A Complete History of The Great Flood at Sheffield
by Samuel Harrison
Web Page 30

(120 contd.)

Mr. GUNSON, on re opening, was recalled and examined by the Coroner: The parliamentary plans are not here, only the working ones. The former can be given by Mr. Rawlinson. The plans carried out were not precisely the same as the parliamentary plans. We discovered that the ground where we first intended to put the embankment was faulty;--there had been what we call a land slip. I should say that land slip was some hundred years old. I did not observe it at first. After I discovered it would not be safe, I saw Mr. Leather, and he directed it should be made where it is. We had not begun the work at the first embankment, but the contracts were let. The rainfall of that district from 1859 was as follows:-

Year. Inches.
1859 ... ... ..
1860 ... ... ...
1861 ... ... ...
1862 ... .. ...
1863 ... ... ...

The smallest flow of water in the summer is half a cubic foot per second for each thousand acres of the water shed, and the maximum 150 cubic feet per second per thousand acres. The gauge was placed in the Rivelin valley before we want to Parliament, and when we got the Act, I had it reconstructed. It was 18 feet wide. The heaviest flood we have had occurred in August, 1856. The overflow was sixty inches, and it took away the gauge. The gauge was kept at Redmires, about twelve hundred feet above the level of the sea. On the south side of the dam we have an artificial cutting. That was to divert the stream during the construction of the reservoir, and we used it till about a year ago. The embankment was finished before then, with the exception of where the weiring is at the south end, which is not finished yet. Some of the materials got out of the cutting might be brought into the embankment, others washed away. In August, 1856, we had nine inches of rain--the largest quantity in any month. It would take fourteen or fifteen inches to fill the reservoir, so no flood could materially affect it. When we bared the rocks we had no apprehension that mischief could arise: and I was perfectly satisfied that no water coming from the rocks could injure the embankment, because we sunk the puddle trench far down into the rock below any excavations in the reservoir. It was put down into measures quite impervious to water. The water seen coming out of the rocks where the reservoir has been flows into the river. It is possible it might drain into the embankment, but it would be stopped by our puddle. It was not at all a hazardous proceeding to bare those rocks. We might have got material elsewhere to make the embankment if we had bought 100 acres of land for the purpose. There are about 400,000 cubic yards in the embankment. We should not have required 100 acres if the material was anything like. I cannot say how many acres of the rock we have bared; eight or ten, I should guess. We did not find all the material of the embankment in the baring of the rock.

Mr. RAWLINSON asked if it was not a mistake that they had laid bare so much of the rock, because the larger portion of the bottom of the reservoir was covered with a pervious shale ?..... Witness said there was very little which they had bared which was not rock in some form or other, though parts might be covered by shale.

Examination continued: Some of the puddle was got close to the embankment---some was brought from nearly a mile above. We first let water into the reservoir last June, and the water rose in the dam in two days upwards of 50 feet. The pipes were then closed. Some water came out of the rocks and got behind the embankment. The water coming into the reservoir by the flood was quite thick. The water from the rocks was clear as any crystal, but strongly impregnated with iron and sulphur. The water came from the rocks, but could not come out of the reservoir. He was confident that no part of the water came through the puddle wall. When there were fifty feet of water in the reservoir, many of those rocks visible now were not visible.

The CORONER pressed the question still further as to the water coming from the reservoir and getting behind the embankment, and there were several attempts to explain ....... Mr. Leather said the misunderstanding arose from Mr. Gunson speaking of rocks outside the embankment, and the Coroner thinking he meant those within.

The CORONER said he was satisfied with the note he had taken, and should draw his own inferences.

Examination of Mr. GUNSON continued: We are making the Agden reservoir on the same principle, except that the puddle trench is not below the outlet pipe trench ...... The pipe is placed on a puddle trench in the solid rock ...... I suppose the principle of construction is the same ? --- I hope not ........ Supposing it does burst, what will be the effect?--The same as we have seen .......... You don't anticipate that it will burst ? --- No ....... The Coroner: But I do.

By the JURY: The excavations were not made to any great depth. I thought the embankment perfect up to the time of its giving way ....... Your work at Bradfield not being perfect, have you not reason to think that the Agden work will not be perfect ? --- No ........ Suppose a pipe is fractured, how are you to discover and reach it ? -- - That would be a difficult thing, but it is not impossible ........ Would it not be better to provide in the original plan for getting at a fracture ? --- Yes, if we had assumed there would be a fracture, but we did not.

The CORONER said the engineers ought to have assumed that a fracture would take place, and to have taken precautions accordingly. It would have been much better to have so constructed the dam originally as to have enabled them to get at any fracture in the pipes rather than to wait until an accident compelled them to devise means to get at it. The witness said he did not apprehend any danger.

The CORONER said that was the fault Mr. Leather and the witness had committed. Neither of them would look before him.

The WITNESS: We have made eight reservoirs.

The CORONER: Then you have made eight mistakes.

Mr. THOMPSON thought these were observations which ought not to be made in the present? of the jury.

The CORONER said he should make them at some other time if he did not make them now. He only wished to get the engineers to speak like rational men. It was not a question of criminality or liability in any way, but the engineers ought to have devised some means of avoiding the danger before they made the reservoirs. Here nothing of the kind had been done, although everybody else could see that the method of construction was full of danger. This was a most serious matter, for they had lost 250 of their fellow townsmen from an accident that ought not to have happened, and which might have been avoided. No man who had looked at the place could say that the accident might not have been avoided. The company were constructing another dam on the same principle, and there would be the same mischief.

Examination resumed: I visited the dam three or four times a week, and sometimes oftener. I generally went on a stormy day. I was there the day before the flood, and also on that day. I went on stormy days to see the effect of the wind on the water. On the day of the flood I went because I had seen Admiral Fitzroy's prediction of a gale. I also had noticed that the wind would be blowing down the valley. I think the wind would not have any effect on the embankment. I have seen the wind and the waves ten times worse at Redmires. I did not observe the least sinking of the embankment, though I was watching it all the afternoon. I stood so that I could see the water level all the way across the embankment, and should have seen any sinking if there had been any. I did not cross the embankment that day because of the spray. I saw nothing of the crack that was seen afterwards. I could not have saved the embankment if I had seen the crack; at least I think not. Opening the pipes would not have had any good effect; for that was done. I have no idea what caused the crack. When I first saw it, a little after eight o'clock in the evening, I thought the action of the wind and waves, which had been playing against it all the afternoon, might have loosened the material of which the inner slope at the top of the embankment was made, so as to withdraw to some extent the support of the puddle wall, which would thus lean forwards and cause a crack in the embankment. I had gone home that afternoon without doing anything, being perfectly convinced that all was safe ...... There is a rumour that you had said, during the day, something about the embankment giving way. Is that so ? --- no. I never said such a thing, and never expected it would burst. After returning home, I received a message from Bradfield that I and Mr. Craven were to go up, Mr Hammerton having observed a crack in passing over the embankment after the men had gone. When I got there the valves of the outlet pipes had been opened, and the water was running freely through them. I did not notice the slightest escape of water through the pipe trench.

By Mr. RAWLINSON: There were pipes at the end of the valve to carry out the water coming through the pipes. I believe all those pipes are there yet. To give the pipes a thorough examination would take from 6 to 12 months, because on the outer side of the puddle gutter the embankment is yet perfect, and there is a great deal of puddle on the other side. To expose the whole length of the pipes would probably cost £2,000. On reaching the embankment, after being sent for on the night of the flood, I found our foreman, Mr. Craven's partner, and the workmen waiting for me with lanterns. I examined the crack, which was ten or twelve feet from the top of the embankment measuring down the slope. I could just get my fingers edgeway into the crack, which was longitudinally on the embankment. I cannot say the length. It was where the breach is. The water was not coming over the top. I came to the conclusion that I had found a satisfactory explanation in the theory I explained. I came to the conclusion that if we could get the water a few feet down, we could so far relieve the pressure as to put a stop to all danger. I ordered the men to blow away the upper stones of the by wash, intending to make a broad opening for that purpose. I thought it was merely a surface crack and by getting the water below the surface of the level we should do away with all danger.

By Mr. RAWLINSON: I intended to make an opening sixty feet long in the by wash. There was a drop in the by wash which would have let all the water of that breadth go off. We were not able to make the breach in the by wash I heard the shot go off after the embankment had burst. The water lowered rapidly in the meantime, though I did not see how much. After setting the men to work I said to the foreman, we will go carefully over the crack and examine it again. We did so, measuring from the top of the embankment to the crack to see whether the rack was above or below the surface water in the reservoir. We walked carefully over the crack, I stooping with a lantern to examine it. All seemed to be right--just as when we walked over it half an hour before. When I got to the end of the crack I straightened my back. The moment I stood up I saw that the water was foaming like a white sheet over the embankment. It came down to my feet, and dropped down the crack. I crept down the slope of the embankment, and got into the valve house, thinking I could come to some idea as to quantity. Mr. Swinden, who had more foresight than I at the moment, would have me out, saying it was dangerous. I turned round and came out. I cast my eyes up and saw an opening thirty feet wide in the top of the embankment like a weir. I had no sooner put my foot on solid ground than another tremendous rush of water took place, and shook the ground under my feet. I knew then that all was up. As I got half way down the embankment I saw one of our men coming from a house near with a lantern. I said run to Joseph Empsall's as fast as you can, and get him out of his house. Empsall's was the first house down the side of the river. He did so. He told me afterwards that he ran himself out of breath, and then sent other men forward. I followed the messenger. When I got to Empsall's house he had just come out, and he told me that he had got away his family, his cows, and everything except his pig. Before he had told his tale, another tremendous rush of water came and swept his cottage away like chaff. I went forward to Lower Bradfield, and found the flood at its height. Some time afterwards I was informed that it had subsided. I learnt that the bridge, corn mill, and schoolhouse had been swept away; and that a child was lost. I stayed at Bradfield all night. We knew nothing more until next morning, when we went up to examine. I never knew that there was any danger until the water flooded over the embankment, and there was then no time to send and warn people below to any greater extent than I did warn them. We could give no warning, nor do I think the workmen apprehended danger before, so as to give the alarm. The embankment gave way about half past eleven. The accident was almost instantaneous. In the afternoon, at half past five, the water would be at least six feet from the top of the embankment. When I had got down the valley about a mile from the dam, the flood was at its height; but at half past twelve, I was told it had subsided within the banks of the river. The descent from Bradfield to Owlerton is at the rate of about ninety feet per mile. The water in the reservoir had risen very gradually before the accident. On the 10th of March it was two feet three inches below the weir; on the 11th it was one foot three inches below.

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