DIFFICULTIES AT MARSHFIELD

DIFFICULTIES AT MARSHFIELD

Marshfield, Wis., has for sonic time suffered from an inadequate supply of water, and in October last the daily pumpage was 198,000 gals, for a city of some 6,000 inhabitants, even after the original system installed some fourteen years ago had been increased in the summer of 1904 by putting down thirty 2-in. well-points into the sandbed containing the water. This bed is about 14 ft; thick and lies about 12 ft. below the surface. When first tapped, the water was received in a large, round, brick well, with which were connected wooden galleries. The new Cook wellpoints were put down into the bed about 500 ft. from the pumping station; but the supply kept decreasing to such an extent that last summer a bond issue of $35,000 was voted to increase it and purchase a new equipment for the electric light plant at the same time. To increase the water supply was a work of difficulty, owing to the peculiar situation of Marshfield (high and dry on a terminal moraine of an earlier glacial period), with no appearance of any appreciably large stream within seven miles of the city. The ground supply, therefore, must be further developed or recourse must he had to the Yellow river, flowing seven miles to the south. Tt being determined to adopt the first alternative, special test wells were put down about 70 ft. to granite on a line crossing the valley near the pumping station. At one of these wells an underflow test was made by means of the Slichter electrical method to determine the direction and velocity of the water. The latter was only 8 in. per day. and the former about 1 65° F. T he lower sandbed was selected as a source of supply. Sixteen tubular packed wells will he put down into it, with screens as long as the depth of the sand at that place. These screens will he of 35’5-in. wrought iron pipe, with of No. 4 sheet-brass. In putting down the wells a 12 in easing is used till rock is reached and the connecting pipe is lowered in the well and the space filled with t-to-in. to J-in. screened gravel, fter this gravel is in place, and the 12-in. casing has been removed, there is left a screen, with .⅛in. holes, surrounded with gravel of the size already mentioned. The space between the wells will he from 35 to 40 ft,, and the horizontal section-pipe will lie 12 ft. 6 in. below the surface, just above the surface of the ground water. The pump will he of the high-lift centrifugal type of the vertical type, with an electrical induction motor and a capacity, when both pumps have been installed of 1.200 gals, per minute. There will also be an artificial ground supply, in addition to the natural ground-water supply. An earth dam will be built across the little valley at the pumping station, to store the surface water which flows from an area of 417 acres. Inside of this reservoir wells will he laid to the granite intersecting the sandlied that supplies the packed walls from which the water is to he pumped, and these will he put down iust as those that supply water to the pump, with the exception of having no screens and of having the entire hole from the rock to the surface of the ground filled with coarse, screened gravel. A small filter will he built over the wells, the object of which is to remove any sediment front the water and to provide an intake to control the water flowing into them. It is exnected that at least cjo.ooo.ooo gals, of water will be furnished every vear, and, including the per eolation on the drainage-area, the average daily supply will be 556,000 gals , instead of only 167.000. as at present, to say nothing of what may be drawn directly from the lower sandbed. The whole cost is Set down as being likely to be $2.35 per ft.

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