16 16 16 1.8 98 06: 2.11 0.0 10-1 104 C 83 85 83 84 86 86 46 x6 87 88 88 qt $NNEL LINE EXISTING PROJECT -7-༡མ་ PANY ANNUAL REPORT FOR 1893. By submitted: t. of Engrs S.A. to recover the loose blocks remaining. Cross-sections made at this time, taking the depth at intervals of 10 feet in each direction, developed but two shoal soundings, loose blocks since removed. On drifting a sweep over the section, however, other loose blocks were detected and the section could not be reported as finished at the close of the year. Of the facts worthy of note concerning this half-year's work were, first, the increased hardness of the rock. The amount of explosive used per cubic yard of rock removed was three times that required on the preceding section. With this increased expenditure of power the average daily cube removed was maintained. This was accomplished, however, largely by reason of a reduction of 35 per cent in the amount of time lost, due to the strengthening of weak parts that had been going on, and by improvements giving increased efficiency, that had been suggested by previous work. It was found that better results were obtained, with the same amount of explosive by using heavier charges at longer intervals; and 50-pound charges spaced from 10 to 15 feet apart became the practice. Durable dipper teeth were secured. The set described at length in the Report of last year more than fulfilled their promise and have been in use the entire year. To test the efficiency of cast-steel teeth, a set of exactly the same pattern, made at one of the best-known foundries, and of a quality of steel as seemed, in their experience, best adapted to the work, were tried. All of the set were fractured after a few hours' work. A place measurement of this section was made from surveys after completion of the work, showing a ratio of 1 to 2 as compared with the scow measurement reported. This is the same result as found last year. A place measurement was computed, also, as the work progressed, by calculating the water displacement of each scow. As a portion of the load is submerged in the scow-wells this method was considered uncertain until the surveys were made and a close agreement found in the two methods. The displacement measurements have been continued as being more reliable than an estimate of the rock in irregular masses. When the plant came out of winter quarters it was in better condition than ever before for performing this work. The hull of the dredge had been strengthened under the turntable, dippers repaired, worn-out chain renewed, machinery overhauled, all rivets tested, and extra spuds, dipper teeth, etc., provided. The tug having been out of commission for a year required extensive repairs, including new stern bearing, lead sleeve, increased steering power, new bits, roof covering, etc. Two of the dump-scows were decked over and adapted to the new order of the work proposed. Much of this work was performed by the crews employed upon the plant. The approved plan of work for the year 1893 involved two radical changes; one in the method of placing the charges upon the river bed, and another in the disposal of the rock removed. Hitherto most of the rock had been deposited with the gravel at the shoal water dumping ground in the Lower Raritan. The construction of a riprap dike of the Raritan shale was begun along the line of the proposed earth dike C. After the timber dikes were built in the Raritan it was found that the channel dredged between the north shore and the line of dikes was shoaling at a locality where it had been impracticable to secure a uniform section by a single line of dikes. This shoaling continued and in 1888 a dike to be built along the north shore with the material dredged from year to year was planned to remedy this defect. Its construction was discontinued in 1890, after two years trial, because of the light nature of the material, readily wasted, and of the uncertainty in the delivery of protecting riprap. For three years dredged material has been deposited on the flats back of the dikes. Last year the amount of gravel removed was small and promised less for this year. The rock is durable under water, and it is believed that a substantial and permanent dike can be constructed at little or no cost to the work and of permanent benefit to the river channel at this point. This disposal of the rock dispenses with the hired light-draft tug and puts into commission the tug belonging to the plant. The difference between the cost of running the one and the hire of the other is more than enough to pay for unloading the stone into the dike, so that it is being built at no additional cost to the work. One thousand two hundred and seventy-one cubic yards have already been placed in the dike. The stone that has been purchased for this dike heretofore has cost $1.25 per yard. A simple method of accurately and quickly placing charges of explosive upon the river bed independent from the dredge was desirable. A uniform spacing of 6 feet, lengthwise and across, was adopted. A scow 6 feet wide by 30 feet long was employed. Four poles on either side, 6 feet apart, are free to rest upon the river bottom. Eight charges are weighted, connected and wired in the usual manner, and, by an arrangement, lowered simultaneously and left, one at the foot of each pole. A single blast, then, extends over a space the width of cutting made by the dredge and 12 feet in length. The scow is easily handled by oars and two such blasts made during the period of high water. Charges of 25 pounds weight, or a total of 200 pounds to each blast have been employed. Ranges for locating the position of the scow were established. The advantage of systematically placing the charges was at once apparent. The rock was broken more uniformly and seldom was a second blast over the same area required. The first cut of the new section has been completed and shows a gain of 40 per cent in the rate of progress over that made on the first cut of the preceding section. The conditions are the same and the quality of the rock unaltered. About the same amount of rock was removed, and with little increase in the amount of explosive required. There is a promise of a further advance in the completed channel during this year than was made during the last. A comparison of the tables submitted, showing the work during this fiscal year and the last, shows a gain in the totals of time worked and lost; an increase of 50 per cent in the amount of rock removed; and a decrease in the cost of rock work of 15 per cent, assuming a uniform cost for gravel removed of 30 cents per cubic yard. The increase shown in operating expenses is due to amount of explosive employed; the increase in the total for repairs, to the refitting of the tug. During the year, 1,670 linear feet of wale along the dikes was renewed, and 890 cubic yards of rock from the river used in refilling, at a cost of 70 cents per linear foot. Respectfully submitted. Capt. THOS. L. CASEY, C. S. KELSEY, Corps of Engineers, U. S. A. COMMERCIAL STATISTICS. The following statistics relative to the commerce of the Raritan River, New Jersey, during the year ending December 31, 1892, were compiled from statements furnished by parties making shipments over this waterway: Before the improvement of this stream was undertaken by the United States the navigation of the lower 23 miles of its course had been abandoned, and a canal dredged at private expense from a short distance below Washington to Sayreville on the Raritan River. In 1880 the mouth of this canal, on account of its faulty location, had shoaled to a depth of 6.4 feet at mean low water, and the best depth in the canal, some distance above, had decreased to 3.3 feet. Above Washington a depth of 2.7 feet existed to Bissetts, 3ğ miles, and 2.5 feet to Old Bridge, the head of navigation, 64 miles above the mouth of the canal at Sayreville. The range of the tide was 5.3 feet at Sayreville. The town of Washington and numerous brickyards did a commerce on the river valued at $1,249,000. The project adopted in 1880 provided for closing the river below the head of the canal, correcting the direction of the mouth of the latter, and obtaining, by diking and dredging, a depth of 8 feet mean low water to Washington, 6 feet to Bissetts, and 4 feet to Old Bridge, straightening the channel at two points by cutting across the meadow, estimated to cost $194,695. This was modified July 30, 1892, by omitting the proposed dredging of the cut-off above Washington and in front of the brickyards; the construction of dikes H, I, J, K, and L, and substituting therefor the dredging of the section of the river between Washington and the Raritan River railroad bridge, removing about 39,000 cubic yards of material, estimated at 40 cents per cubic yard, reducing the original estimate to $176,975. The amount expended to June 30, 1892, was $69,552.87, with which the direction of the mouth of the canal has been changed, the dikes below Washington completed and maintained, a small amount of dredg ing done on a shoal above Washington, a shoal at the mouth of Washington Canal removed, and a channel dredged 60 feet wide through the canal and 50 feet wide across the shoal in the river below Washington. The channel below the draw of the Raritan River railroad bridge was given a depth of 4 feet at mean low water, with additional width of 25 feet for a distance of 350 feet, and for a like distance above the bridge the width was increased to 70 feet. At Rourke Reach the channel was given a depth of 6 feet at mean low water and width of 60 feet for a distance of 860 feet; in addition a bar opposite Whitehead's Brickyard was removed to a depth of 8 feet at mean low water and width of 60 feet for a distance of 450 feet, and at the junction of the canal and South River a channel was excavated 350 feet long, 60 feet wide, and 6 feet deep at mean low water. The river and harbor act of July 13, 1892, appropriated $7,000 for continuing the improvement, and a project for its expenditure, in dredging a section of the river between the Turnpike or County Bridge and Bissett's, was approved July 30, 1892, the work to be done by contract in accordance with regulations. Specifications were prepared and sealed proposals invited by advertisement, August 9, 1892, for dredging the reach between the bridges above Washington 6 feet deep at mean low water, and as wide as the funds available would admit. Bids were opened September 15, 1892, the lowest bidder being William H. Taylor, of Jersey City, N. J., at 29 cents per cubic yard, measured in scows (abstract herewith). This bid was approved and a contract entered into September 28, 1892, for the removal of about 19,000 cubic yards of material. Work was begun October 3, 1892, and continued without interruption to December 22, 1892, when the formation of ice in the river compelled the suspension of active operations for the winter months, and necessitated the granting of an extension of the contract from February 1 to April 30, 1893, upon the written request of the contractor dated January 23, 1893, approved by the Chief of Engineers, U. S. Army, January 27, 1893. Work was resumed March 29, 1893, and the contract completed April 30, 1893, the total amount of material removed having been 18,028 cubic yards, giving a channel 1,850 feet long, 50 to 100 feet wide, and 6 feet deep at mean low water, extending upstream from the Turnpike Bridge and connecting with a channel of similar depth existing as far as the Raritan River Railroad Bridge, a width of 100 feet being maintained for the first 200 feet of its length, 75 feet for an additional 585 feet, and 50 feet for the remainder. The present condition of the river is such that it may be navigated by vessels of 6 feet draft at all stages of the tide for a distance of about 3 miles above its mouth. ENG 93-71 |