The necessity to retard the flow of or provide storage for approximately 380 square miles of highland drainage area has been determined after careful study, and there has been deduced an amount which may safely be expected to represent the maximum for the highest floods. When the highland tributaries are sufficiently checked the natural storage on Great Piece Meadow in its effect upon flood control becomes more apparent. Our investigations show that the holding back of the flood flow—that is, 8 inches run-off on approximately 380 square miles of flashy drainage area above Great Piece Meadow—is necessary to reduce the discharge in the river through the city of Paterson to 14,000 cubic feet per second for a flood similar to that of 1903.
From the foregoing table, in which different reservoir projects are compared, it is seen that only the reservoirs designated as Great Piece and Mountain View will fulfill the requirements within a reasonable limit of cost. It is also shown that a combination of any other available sites would involve the expenditure of more money for their construction and the control of less tributary drainage area than is fulfilled by the demands of the Passaic drainage basin. We are therefore brought to the conclusion that only two of the projects above set forth will be effective. First, the construction of a regulating dam on the main stream above Little Falls, which we have called the "Great Piece" Meadow Reservoir, and second, the building of a dam at Mountain View across Pompton River. The relative cost of these reservoirs, constructed for flood control exclusively, is $2,625,000 for that on Great Piece Meadow and $3,340,000 for the Mountain View site. Details of these estimates are as follows:
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.[D]]
| Earth excavation, 17,600 cubic yards, at 35 cents | $6,160 |
| Rock excavation, 8,800 cubic yards, at $2 | 17,600 |
| Rubble masonry, 29,100 cubic yards, at $5 | 145,500 |
| Ashlar masonry, 1,800 cubic yards, at $12 | 21,600 |
| Facework of rubble masonry, 2,850 square yards, at $1.50 | 4,275 |
| Concrete masonry, 250 cubic yards, at $6 | 1,500 |
| Slope paving, 300 cubic yards, at $2 | 600 |
| 60-inch cast-iron pipe in place, 360 tons, at $35 | 12,600 |
| Relocation of railroads, Erie, 5 miles, at $20,000; Delaware, Lackawanna and Western, 4.5 miles, at $40,000 | 280,000 |
| Relocation of highways | 170,000 |
| Real estate: | |
| Above Mountain View | 500,000 |
| Additional for village of Singac | 100,000 |
| 22,000 acres, at $50 | 1,100,000 |
| 2,360,000 | |
| Add for engineering and contingencies | 240,000 |
| 2,600,000 | |
| Protection of pipe lines, Newark and Jersey City | 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 cubic 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.
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 | $25,050 |
| Core wall trench, 24,900 cubic yards, at $1 | 24,900 |
| Rock excavation, 10,100 cubic yards, at $2 | 20,200 |
| Rock fill in dam, 197,000 cubic yards, at $1.25 | 246,250 |
| Rubble masonry, 23,200 cubic yards, at $5 | 116,000 |
| Concrete, 30,000 cubic yards, at $6 | 180,000 |
| Gate chambers and tunnels | 65,000 |
| Reconstruction of highways | 142,400 |
| Reconstruction of railroads | 815,000 |
| Real estate | 1,360,000 |
| 94,800 | |
| Engineering and contingencies | 325,200 |
| 3,320,000 | |
| Protection of Newark pipe line | 20,000 |
| Total cost | 3,340,000 |
| [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 | $25,560 |
| Core wall trench, 26,000 cubic yards, at $1 | 26,000 |
| Rock excavation, 10,600 cubic yards, at $2 | 21,200 |
| Rock fill in dam, 214,000 cubic yards, at $1.25 | 267,500 |
| Rubble masonry, 24,500 cubic yards, at $5 | 122,500 |
| Concrete, 30,500 cubic yards, at $6 | 183,000 |
| Gate chambers and tunnels | 65,000 |
| Reconstruction of highways | 142,400 |
| Reconstruction of railroads | 815,000 |
| Real estate | 1,435,000 |
| 3,103,160 | |
| Engineering and contingencies | 336,840 |
| 3,440,000 | |
| Protection of Newark pipe line | 20,000 |
| Total cost | 3,460,000 |