Slike strani

limits their number and extent, which for this estimate I will confine to one for each six miles of the canal; the length of the waste to be equal to the width of the water surface in the canal opposite to it.

Generally, ridges or elevations of ground through which the canal passes may with advantage be selected as the sites of the wastes. For safety in the estimates they will be calculated at the cost of placing them on banks twelve feet high.

These overfalls will not be required until the demand for water causes the full depth of two feet to be run in the canal. Time will therefore be allowed to collect the materials for their construction and for its transportation upon the canal at the lowest rates.

[blocks in formation]

Ways of passing over the canal must be provided. They are not a part of the canal, but are rendered necessary by it. The more numerous they may be, the greater will be the convenience to the public. But the cost of their maintenance, as well as the interest upon the cost of construction, must be paid in the rates of tolls and water rents by the people who employ the canal. The convenience of numerous bridges will, therefore, he weighed with the cost to themselves, until the wealth and population of the country will distribute the expense amongst a great number. At present, I estimate one for each six miles in length of the canal.

To establish and maintain a ferry where the travel is great or the canal narrow, will cost more than the interest upon the cost of construction and the wear and tear of a bridge. Where the canal is very wide, the population scanty, and the passing unfrequent, a ferry may serve for a time. I have, however, thought it best to estimate bridges of cheap construction, and admitting of repair and renewal without interruption to the use of the canal.

To allow free passage to boats plying upon the canal there should be a space of twelve feet between the surface of the highest water in the canal and the bottom of the bridge. They must, therefore, be twentytwo feet bigh, and the earth approaches to them must rise to the same elevation.

The team towing the boat must pass under the same span of the bridge with the boat. This requires that the towing path, and a width of the canal sufficient for the passage of a loaded boat, with the minimum depth of five feet of water in the canal, be embraced in a space larger than is necessary for other spans of the bridge. By means of a wall, a track for the team is made to occupy a part of the slope of the bank under the bridge, and the top of the bank of tbe canal is occupied by the slope of the earth approaches, and by a bent, upon which one end of the long span rests. On account of the great size of agricultural implements used in the valley, and the great weight moved by wagons, the bridge must be of greater width and strength than is usual upon ordi- .

nary roads.

11. Branch Canal from Station No. 341, on the forty-fourth mile to Sacra

mento River, and along the river to the head of Sycamore Slough.

At the time of making the survey in the field, this auxiliary was not thought of, and was not surveyed. It was afterwards adopted in the office, as a means of reducing the width of the main trunk of the canal, in the side hill work in Colusa County, and its capacity by a quantity equal to that of the branch. Three lines of levels across the country enable me to make an approximate estimate of the quantity of land irrigable from it, of the grade required, and of its size and cost. It will be a canal of the cheapest kind, of only two and a half feet maximum depth of water, made in part within, and in part above the ground, by an excavation scraped into banks rising one foot above the water line. It will be fordable at any point, but seven fords covered with stone, and as many bridges for footmen are estimated. No culverts will be needed. Sluices for the distribution of water for irrigation will be small, and of wood; made of the proper size and adjusted to the proper level, they will require no attention except for occasional repairs.

The construction of this branch may be made in such manner as to prevent overflow from the river of lands between the point of its intersection with it and and the head of Sycamore Slough. A few miles of canal inland of the branch, and west from Colusa, will relieve and drain a large scope of flat country at present occasionally overflowed by drainage from the foot-hills. The overflowed area has an average fall of three and a half feet to the mile.

12. Right of way- Acquisition of lands.

At and near the head of the canal there may be a small area of land which will sustain more damage than benefit from the canal, for which compensation in money would be required. But along the route the advantages to the lands resulting from the canal will be so great that nothing more than the marketable value of the land taken would be awarded to the owner, if demanded by him. A large proportion of the lands upon the route are uncultivated and unfenced, and of a part tho title is in the Federal Government, which is liberal in donations for such purposes. Making special allowance for the damage at the head, I estimated the average price of other lands at two dollars per acre.

Restricting the quantity of land to be acquired to the mere strip embraced between and covered by its banks, is always attended with inconvenience and often with loss to the proprietors of the canal. They should exercise the rights of ownership for some distance on each side. I advise tbat a width of ten chains be acquired, from end to end of the canal. This may be taken at eighty acres for each mile in length of the canal.

Branch canal.

A strip of land three chains wide at the head and two at the lower end, is necessary upon the branch. The average width is two and a half chains, and the quantity, twenty acres to each mile in length of the branch.

Extension to Suisun.

The excess of distance of this extension over the line to Cache Creek Slough, is twelve and one eighth miles. The average price of two dollars is applied to the branch and extension.

Plans and specifications.

A requisition is made in the Act for plans and specifications. I do not understand it as requiring, in a survey merely preliminary and experimental, elaborate drawings of the various structures which will be estimated as part of its cost. A written description, which will precede and be combined with the specification, will give the plan of each, from which drawings can readily be made whenever needed. Any plan that I can now present would probably be subject to some modification, required by peculiarity, location, etc. The plans can, therefore, be only general. În like manner, the specifications will be brief and only general, and much of detail will be omitted which would have entered into them if they had been prepared for a letting of the work for construction by contract.

The term "excavation,” used in the following descriptions, plans, and specifications, means the removal of earth from the trunk of the canal and its branches, and all mucking and puddle ditches, side drains, and the inlets and outlets of culverts; pits for the foundations of culverts, aqueducts, locks, flumes, and sluices; the preparation for overfalls, and the opening of channels for streams; the slope of any excavation to be made, and trimmed to the slope and form which may be found necessary for it.

The term "embankment” includes the earth filling over or against all culverts, aqueducts, locks, flumes, sluices, etc.; the filling up to bottom of canal, and the formation of the banks of the canal and its branches; also, the construction of the guard bank of the basin at Red Bluffs. It means eafth, free from stones, sticks, stumps, grass, leaves, and vegetable mould, to be scraped or carted into a bed or foundation prepared for it, and to be spread in horizontal layers not exceeding six inches in depth.

The term “puddle” means earth like that for "embankment,” spread in layers not exceeding ten inches in depth, made wet with water, and cut or worked with the shovel until it becomes cohesive and stiff enough to bear the weight of a man.

Ву “mortared masonry " is meant a compact mass of stone, or of brick, or both, of durable quality, well shaped, with fair beds and joints, and mortar made of best hydraulic cement and clean sharp sand. Every joint between two stones must be broken by the stone above it. Head. ers must be frequent. In a thin wall they must bind the two faces together, and in a thick wall, each face with the heart of the wall. No two stones in the work should touch each other, but be interlaid with mortar, the smallest quantity of which that will fulfil these conditions is the best. Each stone should be laid in a full bed of mortar, and be pressed into it. In all cases where embankment or puddle is to rest against a wall, it will have a batter, and will be made smooth and be plastered with mortar, if necessary. The same conditions apply to brick work, which will in all cases be of the best quality, and hard burnt.

Dry walling and paying imply, stone of as good quality as that last described and as well laid, but without dressing the beds and joints, and without mortar; the paving to be always placed on edge. Rock dike, rip-rap, or rock protection, is rough stone thrown in at the foot of a bank to prevent slides, or upon its face to prevent abrasions by water.

Timber and lumber entering into the foundations, especially of masonry and of the sluices, to be of the best quality and perfectly sound; to be square on the ends, and to be hewed or sawed so as to have true faces and joints, and when laid in the work to be water tight. Sheet piling will always be driven with close joints, and so deep that no vater can pass through or under it.








From January, 1864, to February 1st, 1868.


« PrejšnjaNaprej »