History
Sheffield Flood
«ReturnConstruction of Dale Dyke Reservoir
The Bradfield reservoir was probably one of the largest works of the kind in the country; and if it had been successful it would have been a monument of engineering skill of which the Water Company and the town might well have been proud.
It was no light work to attempt the construction of a dam which should intercept and contain the drainage of such a space as that which formed the water head of the Bradfield dam; and the progress of the works has been watched with the utmost care by the directors and every one of the officers of the company, who gave to it an amount of attention that its magnitude imperatively demanded.
The situation of the reservoir has been previously explained, and no doubt many thousands of our townsfolk have visited the spot during the week; but impressed as they might be by the stupendous character of the undertaking, they could not form even an approximate idea of the labour involved in its construction, and the enormous quantity of material that has been employed.
The reservoir was intended to provide the compensation water which the company was bound to supply to the mill owners on the Loxley, and the surplus would have been available to meet the requirements of the town. It was therefore made of vast capacity, and in addition to intercepting the waters of the stream called the Dale Dyke - which becomes what we call the Loxley at Low Bradfield - it was intended to hold the drainage from a gathering ground of not less than 4,300 acres.
The first sod was turned on New Year’s Day, 1859, Mr. Leather being the consulting engineer, Mr. Gunson, the resident, and Messrs. Craven, Cockayne, and Fountain severally undertaking the contracts.
Speaking of the dam as it existed on Friday morning, we may state that the area of the water it contained was 78 acres, - truly a splendid sheet of water, forming a lake which glistened in the bosom of the hills with all the picturesque beauty of a Highland Loch. From the dam head to the embankment the sheet of water spread out for more than a mile in length, and a quarter of a mile in width, and contained upwards of 700 millions of gallons. In the centre the depth was between 80 and 90 feet. It will be seen that an embankment of tremendous strength was necessary to resist the pressure of such a mighty volume of water; and the engineers constructed one which they believed would be strong enough to obviate the possibility of danger.
For more than three years a small army of navvies have been labouring incessantly at the erection of an earthwork which was worthy of the gigantic scale upon which modern engineering is carried on.
At its base the embankment was 500ft wide - owing to the peculiar fall of the hill sides, it exceeded that width in some places - 100ft high, and 12ft wide at the summit.
In order to secure a perfectly sound foundation, an excavation was made to the depth of not less than 60ft, so that there was as much of the embankment below the ground as above. This vast work stretched itself across the valley for a space of 400 yards. The water face was of course enamelled with masonry; and running lengthwise through the centre was a puddle trench 17ft in thickness, formed, as is usual, in puddle clay, which was thought to be perfectly impervious to water. The foundations of this wall of "puddle," upon which the safety of the embankment depended, were driven 60ft through the solid strata.
The weir that was provided to carry off the overflow was 60ft wide, and it conducted the water down a stone channel into the Loxley. All the other means for carrying off a large head of water rapidly were provided, as the engineer thought, on a sufficiently large scale.
It may not be uninteresting to state that the Bradfield dam was only one of a series of immense reservoirs which the company were constructing or intending to construct in that neighbourhood. One of them, the Agden reservoir, is situate a mile nearer Sheffield. It intercepts the Agden, and is intended besides to contain the drainage of an area of gathering ground about equal to that which supplied the Bradfield dam. The embankment is even larger than that which has given way, and it is fast approaching completion.
Higher up the valley, beyond Bradfield, the company was already "prospecting" for the site of another reservoir, which would be, if it is made, on a scale equal to the others.
