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Lock No. 20, is at the head of this rapid descent in a parrow defile caused by the sudden approach of high rocky banks on either side of the creek. In passing this point, considerable rock excavation will occur, owing to the necessity of cutting the body of the canal into the steep side hill for about 20 chains on the north side of the creek. The embankment must be protected by a stone wall. The rock is principally gray sand stone, and easily quarried. It is fine building stone, and will be useful in the construction of locks.
Upon this rapid, Willard Bruce, the proprietor, has erected a saw-mill, fulling-mill and grist-mill, with two run of stones, which, together with 100 acres of land, is valued at $2,800.
He has 12 feet head and fall, and water sufficient in the dryest season to turn one run of stones. The mills will be injured by the canal, and be a subject of claim for damages; but the land will be enhanced in value.
Between the mouths of Black and Crawford creeks on the Genesee river, there are several slide banks of a serious character, which are entirely avoided in the present location. At the point of leaving Black creek, about one mile above its junction with the river, is a favorable valley putting through the high grounds, which bound Black creek valley on the north, through which we pass (2 miles,) in a very direct line, coming out upon the Genesee river one-fourth of a mile south of Ketchum's near Crawford's creek, by which we not only avoid the slides, but save nearly two miles in distance. Here, from a feeder of 20 chains in length, and a dam of small elevation, the whole of the Genesee river may be received into the canal.
The distance from the summit to this point is 94 miles—the descent 242 feet. To overcome this fall, it will be necessary to construct 27 locks of 8 feet lift, 2 of 7 feet and 2 of 6 feet.
There are 3 culverts, 5 waste-weirs, 9 road and 14 farm bridges required on this portion of the route. Estimated cost $223,052.35.
Following down the river from this to Portageville, 20 miles, the valley is often wide, free from high, precipitous, rocky shores and (with the exception of some obstructions by slip banks of clay,) presents unusual facilities for the construction of a canal, and (as will be seen by reference to the estimates for each section in detail,) bears a remarkable comparison with the same distance on the east side of the Genesee river from Mount Morris to Rochester, lockage excepted.
The principal and indeed the only serious slide bank we have to encounter, is on section No. 38. It is a high steep bank and embraces several acres of ground. At this point (as seen on the map,) the Genesee runs nearly at right angles from the east to the west side of the valley, and after washing the base of the slip bank, continually increasing its depth, (now 20 feet,) as well as increasing the tendency of the bank to slide, it makes off again across the valley, touching the eastern hill within 22 chains of the point of leaving it.
To secure against these slides is difficult-great disasters are of
ten occasioned by them, and in order to get by this point with safety to the canal, I propose changing the bed of the river and constructing the towing path on the opposite bank of the old channel.
Near the hill on the east side of the valley, is a natural ravine, through which, by the erection of a strong dam across the river, and cutting down a narrow ridge 5. chains in length, the Genesee river may be turned at comparatively a small expense, which is the most feasible plan of avoiding all danger from the slide.
The Genesee sends forwards 5,007 cubic feet of water per minute at the point proposed to take it into the canal, as a feeder above Crawford creek.
From Crawford creek to Portage we cross Caneadea, Cold and West Koy creeks, all fine permanent streams, discharging in the dryest season 2,800 cubic feet of water per minute, which may be received into the canal with facility.
The least expensive mode of crossing these streams would be by the construction of dams with wooden towing paths; but as the crossing of ponds of this description is often attended with great inconvenience from the strong current in the time of freshets, I prefer, and have adopted the more expensive plan of crossing in aqueducts, and introducing the several streams by short feeders with appropriate bulk-heads.
In case it should be deemed necessary hereafter, the Genesee river may be taken in at several points between Cold and West Koy creeks.
On this 21 miles and 30 chains, there will be 3 aqueducts with wooden trunks, 1 with stone arches in cement, 14 culverts, 3 wasteweirs, and 20 road and 35 farm bridges.
At Portage the continued high grounds which come down from the east and west sides of the river and enclose the valley and fertile flats above the falls, are separated only by a deep chasm through which the river passes, with high perpendicular banks on both sides, descending 274 feet by 3 successive falls in the distance of 2 miles.
The perpendicular banks generally are of aluminous shale or gray wacke, with occasional strata of sand rock of a texture sufficiently hard for building purposes, and at some few points between the second and third falls, the banks are 400 feet above the level of the river.
Judge Geddes in his report of 1826, proposed passing this point by going round in the bed of the river. Mr. Jones' plan was to tunnel the hill at a favorable point. To pass this ridge, by either of those routes, appeared exceedingly difficult and expensive. Different plans were proposed, various routes suggested, any many examinations made on both sides of the river, with the view of finding some one more feasible, but without success,
Finding no alternative, but the adoption of one or the other of
those routes, and having some doubts which was the most favorable, I deemed it advisable to make a minute survey and estiinate of both, which has resulted in favor of the river route, although it increases the distance above the one through the tunnel, nearly 11 mile, the river at this place making a long circuit round the hill.
The estimated cost of the tunnel route upon the first plan, (which I would recommend) is a fraction less than that of the river route; but the hazard of encountering unforeseen difficulties in tunnelling through a hill where quicksand occurs, has induced me to give the preference to the latter route.
The canal across the river at Portage by an aqueduct 280 feet long, and to maintain the best elevation for passing the ridge on either route, it must be 36 feet above the bed of the stream. The trunk to be of wond on stone abutments, and piers 42 feet apart laid in hydraulic cement. The site for an aqueduct is a very favorable one. The bed of the river is a flat horizontal rock, with high banks, and stone in abundance may be quarried near the spot. (For plan see folio 33.)
In the village of Portageville, the line will run west of the main street, crossing it at a point where two buildings only obstruct the passage, if the line should be located on the river route; but should the tunnel route be adopted, it will be necessary to remove four buildings.
The lines diverge at Portageville--the one pursuing an easterly direction for 65 chains, over the upland slope near the foot of the hill, passes the ridge by a tunnel 26 chains in length-the other following round by the river, runs under a steep bank or precipitous hill, requiring a very high embankment, principally formed in the bed of the stream, and protected from the floods by a heavy stone wall, until it gains the table or upland slope at the end of section 52, immediately below the first falls.
About 50 chains further on, another spur of the hill, comes out abruptly to the deep defile, in which runs the Genesee river, not less than 380 feet below the top of the bank.
After passing this ridge, which rises above the bottom of the canal 98 feet to its summit, and is 22 chains through, the hill suddenly recedes to the east, and leaving the river's bank the line follows along the north slope of Portage ridge, over tables of very favorable elevation, to the north end of the tunnel, which is 2 miles and 681 chains from Portageville.
In making the survey with a view to a line through the hill, it was ascertained that the summit of the ridge was 204 feet above bottom, and that the tunnel would not exceed 26 chains in length.
The soil or upper covering of the hill is of clay and gravelly loam, the hill steep at each end of the tunnel, with a valley below offering great facilities for the deposite of surplus excavation. From the appearance of the rock upon the banks of the river, and in all the ledges of that vicinity, there were strong indications that the excavation for a large portion of the tunnel would be through rock, lying in horizontal strata, easily broken up, yet sufficiently hard to support the arch-way without the aid of masonry, and had it not
been proved by subsequent examination, that the contrary was the fact, the superiority of this route would have been unquestionable.
To determine this point, and to shew the character of the excavation in the interior, shafts were sunk on the slopes of the hill near the ends of the tunnel, where quicksand made its appearance in such quantities, as rendered it quite impracticable to sink the shafts to the level of the canal. It was still the opinion of some that rock would be found after passing the slopes of the hill. To put an end to all doubts that might arise upon the subject, I directed another shaft to be settled near the centre of the ridge, which was carried down through sand and gravel to within 20 feet of the bottom line of the canal, at which point we again encountered quicksands.
To construct a work of this magnitude through such materials, would undoubtedly prove very expensive, and any estimate that can now be made of its cost, must in some degree be founded on conjecture, and of course liable to vary from the truth. However, for the purpose of comparison, I have estimated for a tunnel wide enough to pass two boats, the arch-way to be constructed of permanent stone masonry, with a wooden horse path, and in the following statement present the approximate cost, from the aqueduct to the north end of the tunnel. Cost from aqueduct to south end of tunnel,...... $4,474 45 Total cost of tunnel,...,
Aggregate, ..... 8144,580 97 To pass the point of rocks or deep cut of 98 feet by the river route on section 53, two plans were proposed, one a thorough cut, the other a short tunnel of 16 chains in length. The line here is far enough from the margin of the gulf to insure the safety of the canal, and yet so near that the surplus materials may be conveniently discharged into the bed of the river, which will tend very much to diminish the expense on either plan.
The estimate for the tunnel is $14,240 less than cutting down the bill, and should this plan be adopted, (which I would recommend,) the whole cost for the river route will be $163,232.49 being $18,651.52 more than via the long tunnel.
In the detailed estimate marked H, for the eastern or long tunnel, will also be found an estimate for a tunnel of less width, calculated to pass only one boat at a time, the cost of which is $56,228.57 less than the other; and should this mode of construction be deemed suitable for a work of such magnitude, this may possibly be the cheapest way of overcoming the obstacles at Portage.
From Portage tunnel to the Dansville side cut at Mount-Morris, the descent is 549 feet.
In selecting a line having in it this amount of lockage, particular regard was had to the facilities offered for the equal and proper distribution of the locks.
Several routes were suggested, two of which were minutely surveyed; one through the deep cut at colonel Williams', down the Cashaquo valley, via Nunda, to the Dansville line near Mount
Morris; the other following the same route for 11 miles over an undulating surface, (with some extra cutting through points of ridges,) which continues of like character for about 4 miles, then passes on to a smooth faced country of clay soil on a rocky base, gently declining towards the river, over which the line was continued down the hill at Mount Morris to the junction with the aforesaid Dansville route, and is 145 miles in length. Several er. aminations were made down the hill, which resulted in favor of the easterly line, a profile of which, together with one of the line down the ravine behind general Mills' house, will be found in the atlas, folio No. 171.
In descending this hill, there is a fall of 469 feet in the distance of 31 miles.
In locating the locks on this canal, I have endeavored in all cases to obtain a "pound reach” between them of sufficient length to fill a lock with water without depressing the level from which it is drawn more than six inches.* To keep within the rule, and overcome so large an amount of lockage as will be concentrated in the above distance by single locks, would be exceedingly difficult, and although combined locks are considered objectionable not only on account of the waste of water, but also from the loss of time occasioned when two boats arrive passing in opposite directions, the one arriving last being unavoidably detained until the first has passed all the locks forming the combination; yet in locations of rapid descent, and where the supply of water is abundant, it is deemed advantageous to construct combinations, inasmuch as there would be an important saving both in the expense of building the locks and in the diminution of the quantity of excavation and embankment necessary in forining the requisite “pound reach" for single locks; and there would also be a reduction in the number of lock-houses and tenders. I have therefore in the rapid descent to Mount Morris, located 11 combinations of 3 locks each, 6 combinations of 2 locks each, and 2 single locks. They are all 10 feet list except the two single locks, one of which is 8 and the other 11 feet list, equal in all to 469 feet.
The proper length of level is obtained throughout the line except in five cases which occur at the above point. These vary from 11.10 to 13.35 chains in length; the required surface may however be added by widening the levels, for which liberal provision is made in the estimate.
There is one other combination. It is formed of 3 locks of 10 feet lift each, and occurs about 74 miles above Portageville in the descent to Round Flat, (so named from its peculiar shape.) For length of levels, lift of locks, total distance of each from Olean, and the names of proprietors through whose land the canal passes, see statement L.
This distance of 174 miles is subdivided into 17 sections, on which are located 56 locks, (45 are combined) 7 culverts, 12
This requires that the distance between the locks should be as many chains as the lock below into which the water is drawn, has lift in feet.