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Channel Upstream from Outlet Dam at Pawling.

For drawing reservoir to Grade 425.

The following estimate is based largely upon the United States Geological Survey Maps, which were checked by a stadia reconnaissance by G. A. Taber, C. E., over a part of the line. A survey was started and run for about a mile up over this line, when interrupted by bad weather; there has been no opportunity yet found to complete it, but the following estimate is believed liberal. The elevation of ground along Croton East Branch and Swamp rivers was also determined in part from line of bench marks and elevations kindly furnished through courtesy of Mr. Birdsall by Col. Meehan, Topographical Engineer of the New York Department of Water Supply.

A broad lawn is proposed to be filled in between the Pawling Cemetery and the new location for the railroad and the margin of the reservoir from material dredged from the canal above the sluices, and the eastern end of the East Dike is swung to the northward for that purpose.

Deep channel upstream from Pawling into main reservoir above Hurd's, as per section above, bottom at elevation 415;

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Channel up-stream from Pawling to Hurds Corner.

for drawing Reservoir down to Elev. 425. Size sufficient for Ten Mile plus Housatonic.

bottom width 40 feet-of size and depth suitable for addition of
Upper Housatonic river in future, as per Fig. 84.
Earth excavation on basis of above sketch, not far
from 400,000 cubic yards, at 25 cents....
Assume ledge, 5 per cent., 20,000 cubic yards, at $2..

$100,000

40,000

$140,000

Fig. 84

Or, to be safe, and to allow for depositing a portion of excavated. material in embankment between Pawling Cemetery and Reservoir, say....

(It is quite possible that detailed surveys and test pits will show that by modern methods of excavation by steam shovels or dredging this channel can be excavated for one-half of this sum.)

$200,000

Open Canal from Pawling Outlet Dam South to East Branch Reservoir. The natural features are remarkably well adapted for conveying the Ten Mile or Housatonic water from the outlet dam, southerly into the present East Branch Reservoirs. As shown in the photograph, Figure 78, there is a clearly defined ancient river bed, now a swamp, running southerly all the way from the outlet dam down to a point about half a mile or more below Pawling, where it gradually broadens into a wet, nearly level swamp. The topography and certain geological features strongly point to a river much larger in volume than the present Ten Mile at Webatuck, having thousands of years ago flowed southerly down past Wing, Pawling and Patterson, into the East Branch. of Croton river, along the line now proposed for this canal. The report of the geologist, Professor Crosby, on this subject, found in Appendix No. 16, page 583, is very interesting. Indications are strong that the excavation for this canal would all the way be in soft, wet sand, that could be excavated by a floating dredge of the centrifugal type or endless chain and bucket type, starting at either end and at a cost per cubic yard not more than half that at which this work is figured in the estimate below.

I made personally a brief reconnaissance over a portion of this line, and a line of levels and measurement was begun by Mr. Taber down along this proposed canal, over the frozen surface of the swamp, in order to more closely estimate the cost of excavation, but this stadia survey was interrupted by the sudden flood of February 5. The swamps were again flooded February 13 and remained impassable for survey for some weeks.

A reconnaissance was subsequently made by Horace Ropes, C. E., who tramped over or near to the proposed canal line for its entire length from Pawling to a short distance below Deforest Corners, armed with a steel sounding rod and probed the depth of the mud and examined the characteristics affecting cost of excavation. Substantially the whole appears to be material that could be handled by a dredge and deposited as in Fig. 85 at a cost of say 10 cents per cubic yard. Mr. Ropes' report of this exploration is as follows:

I examined the East Branch valley from Pawling south for 10 miles.

Through the Village of Pawling, for about 1⁄2 mile, the bottom of valley is only from 175 to 250 feet wide; rock shows at points in the bluffs on each side. In this first 1⁄2 mile south of the proposed outlet dam, 4 soundings showed from 3 to 6 feet of sand, overlying what felt like hard packed gravel.

From the crossing of the road running south from Pawling to the end of mile 2 from the outlet dam, the valley grows wider. The bottom, varying from 600 to 1,500 feet wide, becomes swampy in character and seems to be a pocket of deep black muck. My 12-foot sounding rod failed to touch bottom at points which were generally nearer the edge than the centre of this swamp. Mr. J. B. Dutcher told me that when he reclaimed a small portion of this swamp, near its head, he drove a scantling 24 feet long down its full length without reaching hard bottom. For the next 11⁄2 miles, or to about 1⁄2 mile north of Patterson, the bottom still has the appearance of a timbered swamp, but this section is not boggy like the last, the soundings showing 3 to 5 feet of fine sand apparently overlying clay. Clay is exposed in creek bed.

At crossing of east and west road at Patterson, I found 5 feet of mud and then apparently coarse gravel. The United States Geological Survey Map is incorrect in showing a divide 1⁄2 mile north of this last point; the brook is continuous through this gap.

For the next 4 miles south the bottoms are from 1,500 to 2,500+ feet wide and generally

timbered and swampy in appearance. For 1 mile south of the Patterson road there seems to be generally from 3 to 4 feet of fine sand with clay bottom; for the next mile, or mile and a quarter, there is a pocket of 10+ feet of black mud.

For mile north and south of the road crossing near Haviland hollow, the bottoms are high (3 or 4 feet above water line), dry and open; sand and clay 10 feet deep, then coarse gravel. I mile south of this latter road crossing or about 71⁄2 miles from outlet dam, I again found 10+ feet of soft mud about 100 feet from east side of swamp.

At 11⁄2 miles south the formation was 5 feet of fine sand over rather soft clayey bottom, and this continued to a point 81⁄2 miles south of outlet dam, where the valley is narrowed to about 300 feet width by side hills of boulder drift. At this narrow place there may be some boulders found in the bottom, but the indications in bed of the creek pointed more to coarse gravel, with a good many cobbles, but not many boulders.

Southward from here nearly to the end of the tenth mile, it is open meadow, 2 or 3 feet higher than the river, and generally fine sand about 5 to 6 feet deep overlying clay, though I found 10+ feet of mud at one place about 1⁄2 mile north of the road.

At the road crossing, boulder drift encroaches on the valley again, and also again at the end of mile 10.

These intrusions of boulder drift would in each case not affect more than 400 to 500 feet in length of the canal, and are at no place of such nature as to prohibit the use of dredges.

It appears most improbable that ledge would be encountered anywhere along the line of this proposed canal, at any depth of less than 15 feet, unless it may be in the first 1⁄2 mile through Pawling, and even there I am strongly of the opinion that there is generally 10 feet or more of drift overlying it. The general character of the ground appears favorable for excavation by a dredge for substantially the entire length of the proposed canal."

In our estimates we were further guided by the height of ground shown by the contours of the Worthen Map of the Croton Watershed, and by a number of elevations of ground along the bed and banks of the East Branch of the Croton river, kindly given by Col. Meehan from the results of surveys made under his direction during the past season. The ground is so remarkably level that the resulting estimate of quantity of material to be moved cannot be far in error.

If this 150 million gallons of Ten Mile river water were simply let run from Pawling Outlet Dam without any new open canal being excavated, it would find its way along present watercourses into East Branch Reservoir, but there would be claims for damages in making certain meadows more wet, and the railroad culverts are insufficient to pass large volumes. Apart from these reasons I believe a deep open canal for all, or nearly all this distance, well worth its cost as a means of draining the swamp and improving quality of water, although only the Ten Mile river were taken; with the upper Housatonic added this canal becomes an absolute necessity.

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The form of channel proposed is shown in Figure 85. This form of section is designed more particularly for the portion through Pawling Village and for a mile or more below it. The excavated material is to be placed so as to form embankments or dikes on either side of the canal, and with channels for storm water outside these dikes, by which the street wash during a storm, and any chance surface drainage of Pawling Village would be excluded until it had run down a mile or more to a point where it could be ponded, and then let into the channel only by natural, slow, sand filtration. Where the canal

runs through muck it is proposed to cover the bed and banks with a thick

layer of gravel.

The details of carrying floods of the East Branch of the Croton river without wash of the banks of this canal can be arranged later without noteworthy addition to expense.

The brook now entering the head of Swamp river from the west, south of Pawling Dam, would be diverted to above the dam, aad the cost of this is covered in the estimate.

Eleven and five-tenth miles open canal of the general section shown in Figure 85, bottom slope 5 inches per mile, bottom width 10 feet for upper 2 miles, 20 feet bottom width for lower 10 miles, side slopes, 3 to 1, graveled. Estimated earth excavation, 2,200,000 cubic yards, at 25 cents,

including all rock, boulders and hard gravel..

Surface indications strongly indicate this material could be very cheaply excavated and deposited by a floating dredge, of either the centrifugal or endless chain and bucket type, at half this price.

The geological indications are that this channel, so far as line was reconnoitered, lies wholly in the bed of a broad ancient river of small declivity, which has become diverted and its bed deeply filled with water-borne deposits of fine sand, and that little or no ledge would be encountered.

This $550,000 for 11.5 miles averages $9 per lineal foot. A canal of same type, shown in Figure 58, and about the same size of cross-section 3 miles in length, in material probably more difficult, excavated by hand on the Massachusetts Metropolitan Works in 1897, actually cost about $10 per lineal foot.

Land damages along canal

Say 2,000 acres wet swamp, averaging at $25..... $50,000
66
200
grass land, at $100...

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20,000

The land through which this canal would run is mostly a wet swamp, averaging about mile wide, of almost no value in the middle half, but with some good grass land along the outer and drier portions. It would probably be best in the long run for the city to buy outright all of the swamp land at the outset and control it, and convert it by drainage into good grass land, which would improve quality of water collecting in Sodom Reservoir.

SUMMARY

Dam

$550,000

$70,000

TEN MILE WATER SUPPLY RESERVOIR AND CANAL. mile above Webatuck.... Land and dwellings on reservoir site..

Probable damages for taking of mills and all water-power sites in basin; possible damages for diversion of water-power from Housatonic; possible damages for impairment of established business

$1,605,000 2,307,000

900,000

Removal of cemeteries...

Removal and grubbing of trees, stumps and bushes; removing mud from mill ponds and clearing up portion of basin not stripped. Removal of turf, muck and loam from entire southeast arm of basin from Dover Furnace to Pawling, 10 miles in length, 3,100 acres. ..

Change in location of Harlem R. R., about 17 miles at $59,000.. 35 miles new highways and 3 new highway bridges across arms

of reservoirs....

Outlet dam and sluices at Pawling..

Deep channel for drawing reservoir low, sufficient for taking
Housatonic water also if wanted in future....

Storm water channels and filtration dam and diversion of two
brooks in Pawling....

New deep channel 11.5 miles long draining swamp and delivering water into Sodom Reservoir (not absolutely necessary for entire length, and can be extended 10 years hence as cheaply as now)....

Purchase of swamp lands along East Branch of Croton River (say)

Sewage disposal works for Pawling and Patterson (say)..

Total

$80,000

135,000

2,170,000 1,000,000

875,000 135,000

200,000

50,000

550,000

70,000 100,000

.$10,177,000

Add for engineering and contingencies at 15 per cent., instead of the ordinary 10 per cent., because of lack of precise surveys, 15 per cent. on $10,177,000...

Add for contingencies on real estate and other settlements, say..

Total estimated cost for supply of 150 million gallons per day delivered into Sodom Reservoir at 415 feet elevation above sea level, or into Croton Lake and Aqueducts without additional expense ($84,654 per million gallons)....

1,526,000

1,000,000

. $12,703,000

For comparison we note that the estimated expenditure for an additional supply of III million gallons per day to Massachusetts Metropolitan District, now under construction-for reservoir (including complete stripping of bottom), lands, buildings, water rights taken, cost of dams and aqueduct as far as Sudbury Reservoir, was

$11,883,000

This last amount corresponds closely to cost of works estimated above, and tends to show that the cost of Ten Mile supply is not unreasonable for the quantity of water to be obtained.

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