First, the conclusion that only two of the projects above set forth will be effective. Estimate of cost of Great Piece Reservoir, dam at Little Falls. [Elevation of flow line, 178.5 feet. Storage and disposal of 9 inches collected.a] 60-inch cast-iron pipe in place, 360 tons, at $35 Facework of rubble masonry, 2,850 square yards, at $1.50.. 21,600 Concrete masonry, 250 cubic yards, at $6 4,275 1,500 Slope paving, 300 cubic yards, at $2 600 Crushed stone, 150 cubic yards, at $1.50 225 12, 600 280,000 170,000 500,000 100,000 1,100,000 2,360,000 Relocation of railroads, Erie, 5 miles, at $20,000; Delaware, Lackawanna and Western, 4.5 miles, at $40,000.. Relocation of highways. Real estate: Above Mountain View... Additional for village of Singac.. 22,000 acres, at $50 ... Add for engineering and contingencies... Protection of pipe lines, Newark and Jersey City. 240,000 2,600,000 25,000 2,625,000 The effectiveness of a reservoir built upon the lines proposed in the case of Great Piece Meadow depends upon the adjustment of outflow so that the channel below will not be overborne, while at the same time sufficient storage capacity is afforded to hold temporarily the water which enters above the dam in amount greater than the carrying capacity of the outflow apertures. The dam across Passaic River above Little Falls would be provided with apertures which would discharge 12,000 cubie feet per second under the maximum head in the storage basin. As the flood rises these apertures would discharge a constantly increasing amount of water to the maximum, and for a considerable time thereafter the maximum would be maintained, the discharge decreasing after the flood according to the height of water remaining in the reservoir. a Includes water discharged through fixed openings for a flood similar to that of October, 1903. Maximum flow, 12,000 cubic feet per second. i Estimated cost of Mountain View Reservoir. [Elevation of flow line, 202 feet. Storage of 8 inches on watershed.] Earth excavation: Stripping dam base, 83,500 cubic yards, at $0.30.. Core wall trench, 24,900 cubic yards, at $1 Rock excavation, 10,100 cubic yards, at $2.. Gate chambers and tunnels Reconstruction of highways.. Reconstruction of railroads. Real estate... Engineering and contingencies . Protection of Newark pipe line... Total cost.. [Same for elevation of flow line, 204 feet. Storage of 9 inches on watershed.] Earth excavation: Stripping dam base, 85,200 cubic yards, at $0.30. Core wall trench, 26,000 cubic yards, at $1 Rock excavation, 10,600 cubic yards, at $2 Concrete, 30,500 cubic yards, at $6.. Gate chambers and tunnels Reconstruction of highways.. Reconstruction of railroads. Real estate.... $25,050 24,900 20, 200 246, 250 116,000 180,000 65,000 142, 400 815,000 1,360,000 2, 994, 800 325, 200 3, 320, 000 20,000 3, 340,000 $25,560 26,000 21, 200 267,500 122,500 183,000 65,000 Engineering and contingencies Protection of Newark pipe line. Total cost.... 142, 400 815, 000 1,435, 000 3, 103, 160 336, 840 3,440,000 20,000 3, 460, 000 The final recommendation of the committee involves the consideration of two projects for flood storage, one on Great Piece Meadow and the other above Mountain View on the Pompton. In making such recommendations the committee is of the opinion that it must take into account matters of engineering policy with regard to future needs and contingencies, as well as the bare necessities of the present. If there were none other than the single problem of prevention the committee would advise the construction of the reservoir on Great Piece Meadow by reason of its smaller probable cost and its equal efficiency. It is plain, however, that there are many important features of public policy involved in the subject at hand. Population in the valley of the Passaic is developing so rapidly that in only a few years the present sources of water supply will be inadequate. The whole subject of water supply for northern New Jersey demands immediate consideration, and it would not be wise to take up the matter of prevention of flood damage in the Passaic without basing the value of every project upon its adaptability for use in future water-supply needs. By expending $2,600,000 a great reservoir could be constructed upon Great Piece Meadow which could not be adapted for any purposes except to regulate floods; it would stand in season and out of season a huge feature of the valley and entirely useless and inoperative save on the occasion of high water. However great might be the needs of the inhabitants of the Passaic Valley for a conserved water supply, the construction on the meadows, representing an enormous expenditure, would furnish no solution of the problem. It would admit of no enlargement for water-supply storage and would be available for no purpose except flood regulation. When we consider the Mountain View project, however, we find that as a measure for the prevention of flood damages it fulfills all the requirements and provides in addition all the possibilities and advantages demanded inevitably in the near future. The Mountain View site is an ideal one for the reservoir, and its initial development for flood catchment does not involve the expenditure of a dollar that would be lost in the development of the basin to greater capacities for water supply. From its lowest level, at 202 feet above tide, to its maximum capacity, at a level of 220, there would be no depreciation. Every dollar spent in the initial construction would be effective in the maximum development. The probable cost of Mountain View reservoir, estimated at $3,340,000, exceeds that of Great Piece by $700,000. It is realized that to many persons this margin may seem very wide. Let us consider briefly just what it really represents. Suppose, for example, that the Great Piece project is constructed at a cost of $2,600,000. After the elapse of a few years it will be necessary to provide additional storage in the Passaic highlands for water supply or the maintenance of water power. The Mountain View reservoir, or its equivalent in capacity and cost, will then be necessary. The situation will then be as follows: By constructing the Great Piece reservoir in preference to the Mountain View for flood catchment, $700,000 would be saved. We can consider that this amount might be expended to pay a part of the cost of additional conservation above referred to. If, on the other hand, Mountain View had been constructed, there would have been paid on the final cost of conservance the sum of $3,340,000, which, as stated in previous pages, would also have effected flood relief. There would then be the difference between $2,600,000 and $700,000, or $1,900,000, which represents the actual loss which would accrue by reason of the construction of Great Piece reservoir. The engineering committee, after presenting the merits of both Great Piece Meadow and Mountain View projects, therefore recommends the adoption of the latter in spite of its greater cost, because it is believed that in the end the construction of the Great Piece project would involve an expenditure not warranted by public economy or general expediency. GENERAL CONCLUSIONS. 1. Great floods in the Passaic Basin arise only after a specially violent precipitation. 2. Under present conditions floods may be expected at frequent intervals. 3. A part of the damage along the lower valley is the result of encroachments on the part of individuals and public and private corporations. 4. The channel in the lower valley may be improved at certain points by straightening it and judiciously making cut-offs. 5. Without the construction of numerous levees the lower valley channel can not be made to carry great flood waters without damage. 6. Immunity from floods can be effected only by the construction of catchment reservoirs in the highlands or levees in the lowlands. 7. Levee construction would involve more damage than is now caused by floods, and the cost thereof would be prohibitive. 8. Flood catchment reservoirs may be constructed economically and provide storage to compensate for the dry-season flow, thereby maintaining water power at Paterson, Passaic, and other points, and providing for municipal water supply in the future. |