Part 9

This stream has been described in the report on the flood of 1902, already referred to. It contributes a large amount of water to the main artery of the Passaic below Dundee dam, and as the river channel at that point is overburdened under the present conditions because of lack of slope and numerous catchments, together with what is known as the Wallington Bend, it increases very materially the damage caused by floods.

The most effectual remedy in the case of Saddle River floods is that of construction of flood catchments. No studies have been made of the situation in the Saddle River drainage area, but a superficial inspection of the basin shows that opportunities for the construction of flood-catchment reservoirs are not numerous.

SUMMARY OF FLOOD-CATCHMENT PROJECTS.

By following the plans described in the preceding pages absolute flood catchments may be provided above Little Falls on the Passaic Basin for 551.7 square miles, leaving only 221.2 square miles from which flood run-off would flow immediately. The accomplishment of this would involve the construction of Pompton reservoir, which would withhold all flood waters from the northern tributaries. It would leave unprovided for 20.2 square miles on the Rockaway, 71.7 square miles on the Whippany, 46.2 square miles on the upper Passaic, and 83.7 square miles tributary to the Central Basin and not included above.

Leaving Pompton reservoir out of consideration, and conserving flood run-off on the Ramapo, Wanaque, and Pequanac rivers, there would be absolute flood catchment up to a 12-inch run-off over 494.8 square miles above Little Falls. This would leave 278.1 square miles unprovided for, the run-off from which would not overburden the channel in the lower valley, provided, of course, that channel were improved to a maximum carrying capacity.

PREFERABLE RESERVOIR SITES.

The following table and discussion of preferable sites for flood prevention are taken from the report of the engineering committee of the northern New Jersey flood commission:

Table showing detailed facts regarding possible reservoir sites on Passaic drainage basin.

KEY: A: Area of watershed. B: Area of reservoir. C: Height of dam. D: Length of dam. E: Elevation of flow line. F: Storage, watershed. G: Storage capacity. H: Total cost.

--------------+-----+------+-----+------+------+-------+-------+--------- Reservoir. | A | B | C | D | E | F | G | H --------------+-----+------+-----+------+------+-------+-------+--------- | Sq. | Sq. |Feet.| Feet.| Feet.|Inches.|Million| | mi. | mi. | | | | | c.f. | Ramapo | 140 | 2.8 | 65 | 1,700| 280 | 5.5 | 1,768 | $900,000 Wanaque | 83 | 2.1 | 60 | 1,200| 275 | 7.7 | 1,491 |1,000,000 Newfoundland | 52 | 1.8 | 40 | 430| 780 | 8 | 966 |1,800,000 Rockaway | 114 | 4.6 | 28 | 470| 520 | 6 | 1,565 | 600,000 Millington | 56 | 15.8 | 25 | 220| 245 | 31 | 4,060 | 370,000 Great Piece | 773 | 37 | 21 | 1,500| 178.5| 9| 8,950 |2,625,000 Mountain View | 380 | 13.4 | 42 | 2,150| 202 | 8 | 7,200 |3,340,000 Do. | 380 | 13.9 | 44 | 2,380| 204 | 9 | 7,900 |3,460,000 Do. | 380 | 14.3 | 46 | 2,470| 206 | 10 | 8,700 |3,590,000 Do. | 380 | 17.4 | 60 | 3,000| 220 | 17 |15,000 |5,260,000 --------------+-----+------+-----+------+------+-------+-------+---------

With the exception of the Millington reservoir site where the cost of the dam is a small factor, the elevation of flow line in the various reservoirs which determines the capacity was fixed so as to afford an approximate storage equal to a run-off of about 8 inches from the drainage area above each dam site. This amount is somewhat in excess of the run-off for the flood of October, 1903. It was found impracticable on the Rockaway reservoir site to provide for a storage greater than 6 inches. On the Wanaque the amount which can be stored falls slightly under 8 inches, while on the Ramapo it is possible to obtain only 5-1/2 inches, by reason of the fact that with a greater storage capacity the slack water would reach into New York State. The economical height for a dam at the lower end of the Great Piece Meadow, if such dam is provided with fixed discharge openings which will carry a maximum outflow of 12,000 cubic feet per second, will provide a reservoir which will dispose of a run-off of 9 inches on the drainage area above.

The following combinations of reservoir sites, with their respective drainage areas, proportional storage, and estimated costs, give the facts necessary for final deductions:

--------------+---------------+-----------+---------------+----------- | Drainage | Water | Equivalent | Site. | area. |collected. | area | Cost. | | | retarded. | --------------+---------------+-----------+---------------+----------- |Square miles.| Inches. |Square miles.| Ramapo | 140 | 5.5 | 96.25 | $900,000 Wanaque | 83 | 7.7 | 80 | 1,000,000 Pequanac | 52 | 8 | 52 | 1,800,000 Rockaway | 114 | 6 | 85.5 | 600,000 |---------------+-----------+----------------+---------- Total | 389 | | 313.75 | 4,300,000 |======================================================= Ramapo | 140 | 5.5 | 96.25 | 900,000 Wanaque | 83 | 7.7 | 80 | 1,000,000 Rockaway | 114 | 6 | 85.5 | 600,000 Millington | 56 | 31 | 56 | 370,000 Total | 393 | | 317.75 | 3,870,000 |======================================================= Great Piece | 773 | 4.5 | 435 | 2,625,000 Mountain View | 380 | 8 | 380 | 3,340,000 --------------+---------------+-----------+---------------+-----------

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.

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 Crushed stone, 150 cubic yards, at $1.50 225 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.

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 ---------- 2,994,800 Engineering and contingencies 325,200 ---------- 3,320,000 Protection of Newark pipe line 20,000 ---------- Total cost 3,340,000

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

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.