EXTRACT FROM REPORT ON THE SURVEY OF PAWTUCKET

RIVER.

Preliminary Examination of Pawtucket River, Rhode Island.

NEW LONDON, CONN.,

November 8, 1882.

This river was surveyed in 1870 and 1873, besides which partial examinations were made in 1872 in connection with improvements then in progress, and in 1879 very complete tidal observations were made, chiefly with the object of determining the influence of three bridges on the currents of the river. With the information obtainable from the maps and reports of these surveys and improvements a preliminary examination of the locality seems unnecessary.

Since 1867, $52,000 has been appropriated for this improvement, making the depth of channel 7 feet at mean low water, where the available depth had been 4 feet. The dredged channel is 75 feet wide. The mean rise of tide is about 5 feet.

The last appropriation made for the Pawtucket River was in 1873. Since its expenditure the business of Pawtucket has greatly increased, and there is a demand for a channel of greater depth and width.

It is to obtain a project with estimates for an enlarged channel that this survey is desired.

Pawtucket is a manufacturing place of about 30,000 population; the improvement desired would be of general benefit to the community, and is undoubtedly one worthy to be made, and the work a public necessity, if the cost be not unduly great. This latter can be satisfactorily determined only by survey.

In my judgment, the survey ought to be made, and I recommend an allotment of $500 from the general appropriation for surveys for this purpose. If the fieldwork is to be done this fall, the allotinent should be made by telegraph.

Respectfully submitted,

Brig. Gen. H. G. WRIGHT,

Chief of Engineers.

J. W. BARLOW,

Major of Engineers.

Survey of Pawtucket River, Rhode Island.

ENGINEER OFFICE, U. S. ARMY,

NEWPORT, R. I., November 8, 1383.

GENERAL: I have the honor to submit herewith a plat of the survey of Pawtucket River, Rhode Island, and estimates of cost of its improvement which were authorized by the river and harbor act of Congress of August 2, 1882, and placed in my charge by your instructions of April 24, 1883.

DESCRIPTION OF THE RIVER.

Pawtucket (or Seekonk) River, an arm of Providence River, extends from Providence to Pawtucket, a distance of about 4 miles, and forms a tidal basin of about 1 square miles. The mean rise and fall of the tide is about 5 feet. The continuation of the river above Pawtucket is called the Blackstone River, and is not navigable. At the mouth of the Pawtucket it is spanned by two bridges, parallel and about 250 feet apart. The upper, the old Washington Bridge, is a highway bridge, and the other is a railroad bridge belonging to the Boston and Providence Railroad Company. The draw of the Washington Bridge is close to the eastern shore, and is so narrow and illy located and constructed as to render navigation through it difficult and dangerous. By reason of this obstruction to the navigation of Pawtucket River, my predecessor, the late General Warren, declined for several years before his death, in August of last year, to estimate for further appropriations for its improvement; but the legislature of the State of Rhode Island, at its January session of this year, enacted a law by which a new drawbridge is to be built on or near the site of the present bridge. This law requires that the bridge shall be completed within two years from the appointment of a board of commissioners; that it shall have a swing draw with two openings of not less than 80 feet wide each, and that the channel of the river under and around the present bridge shall be cleared of all obstructions to the tidal flow to a depth of 15 feet below mean low water.

The railroad bridge does not seriously obstruct the tidal flow on which the maintenance of the channel of the Pawtucket depends, but the draw of this bridge is also badly located, and is too narrow. The draw openings are only 60 feet wide, and fender piles reduce the available width to about 47 feet. It is probable that when Washington Bridge is rebuilt the navigation interests and the town of Pawtucket will demand and effect an amelioration of the draw of

the railroad bridge.

About four-fifths of a mile above Washington Bridge is Red Bridge, with two draw openings of 80 feet wide each. These openings were dredged in 1875 to a depth of 12 feet at mean low water.

The natural channel of the Pawtucket before improvement had a ruling depth of about 5 feet at mean low water. From 1868 to 1875 this channel was dredged to a width of 75 feet, and to a ruling depth of 7 feet at mean low water, under several small appropriations, amounting in all to $52,000.

SURVEY OF 1883.

The recent survey was commenced in the latter part of August last by Mr. W. H. Lawton, jr., assistant engineer, and a party in the United States schooner Surveyor. The entire river from Red Bridge to Pawtucket Bridge was first covered by a system of triangulation. In the subsequent sounding operations, the location of each sounding was determined by two angles turned from the sides of the triangles which were used as bases.

After the completion of the soundings the Surveyor was again sent to the river with a boring party under the charge of Mr. John S. Engs, jr. Mr. Engs, with the assistance of Captain Case and the crew of the schooner, made a large number of borings in the bed of the river, the results of which will be found in tabular form on the plat of the survey. Each boring was located in the same manner as the soundings, and was driven to a depth of 12 feet below mean low water except when stopped by ledge rock. In such cases, a few of which occurred in the upper part of the survey, the table of borings shows the depth to the ledge. In connection with the soundings the borings enable us to form a very close estimate of the quantities of materials of various kinds necessary to be removed in the improvement of the river, and in case of further appropriations for the work they will be of service to ourselves and to bidders in estimating the cost of dredging the sections into which the channel may be divided for contract. The river having been carefully surveyed in 1873 by Mr. H. A. Bentley, assistant engineer, under the direction of the late General Warren, I deemed it unnecessary to run the shore lines again, or to sound out the broad areas of shallow water which occupy a large portion of the river between Pawtucket and its mouth. The shore lines on the plat herewith, except above the gas company's wharf, have, therefore, been taken from the plat of the former survey.

CHANGES SINCE THE SURVEY OF 1873.

At Red Bridge the eastern passage of the draw, which was dredged to 12 feet at mean low water in 1873, has more than kept its depth. The least depth now existing in that passage is 18.7 feet at mean low water. In the western passage the depth remains practically the same as in 1873.

From Red Bridge northward to opposite the north end of Sand Point the channel remains practically in its position of 1873, and carries the same depth

except at the red buoy southwest of Narragansett Boat Club house, where a slight shoaling of about five-tenths of a foot has taken place for about 400 feet.

Opposite the north end of Sand Point the 9-foot contour in the channel has moved down stream about 300 feet. The 6-foot contours remain about the same as in 1873.

Between Sand Point and Swan Point wharf the channel remains the same as in 1873, except that the 6-foot contours have moved slightly towards the right or west bank of the river, and a shoaling of from 1 to 2 feet for about 300 feet has occurred just north of Butler Asylum wharf.

Shoaling has occurred in the channel off Swan Point wharf. The portion of the channel southwest of Swan Point wharf, which was dredged to 9 feet at mean low water in 1873, has now a maximum depth of 7 feet at mean low water. Off the northwest corner of Swan Point wharf the channel, dredged to 9 feet at mean low water in 1873, has filled about 2 feet on the average.

From Bucklin's Island to the wharf of the Pawtucket Gas Company there has been a general shoaling of the channel from 1 to 2 feet. The most marked change in this part of the channel is shown between Bishop's Point and Dunnell's wharf, where the depths of water in the portions dredged in 1873 to 9 feet at mean low water now run from a least depth of 4 feet to a greatest depth of 74 feet at mean low water, although between 6 and 7 feet can still be carried through this part of the channel.

The most marked filling has taken place, for a short distance, opposite the north side of the Pawtucket Gas Company's wharf. Here the channel has been crowded over close to the western bank by the shoal formed by deposits brought down by a sewer on the east bank of the river. In 1873 a cut was dredged to 7 feet at mean low water; this has been filled from 2 to 3 feet.

Dredging has been done from time to time, by private individuals, between the gas company's wharf and Pawtucket Bridge, and no useful comparison can be made in this part of the river between the surveys of 1873 and 1883.

PRESENT CONDITION OF THE CHANNEL.

It will be observed from the above and from an inspection of the plat of the recent survey, that the deposits in the channel since 1873, or during an interval of ten years, are not excessive; that the channel which had been dredged from a ruling depth of 5 feet to one of 7 feet at mean low water has held its own as well as could be expected, and that a draught of from 6 to 7 feet can still be carried at mean low water from Pawtucket to the mouth of the river, although the channel is narrow and in some places tortuous.

MATERIAL OF THE BED OF THE CHANNEL TO A DEPTH OF 12 FEET BELOW MEAN LOW WATER.

The tabular statement found on the plat of the results of the borings in the bed of the channel shows that in going up river from the deep water near Red Bridge to Swan Point, a distance of about 6,500 feet, the material is almost entirely mud; from Swan Point to a point opposite Grant & Co.'s wharf, at Pawtucket, a distance of about 9,000 feet, the material is mainly gravel and sand, interspersed in the upper part of this distance with stones; thence to Pawtucket Bridge, a distance of 750 feet (from boring 82), we find ledge rock appearing at depths less than 12 feet at mean low water. Seal Rock, a part of this ledge, projects into the channel in front of Grant & Co.'s wharf. The top of this rock is 24 feet above mean low water, and a large part of it must be removed in carrying out any scheme for the improvement of the upper part of the river.

THE REASONS FOR THE DEMAND FOR FURTHER IMPROVEMENT OF THE RIVER AND THE AMOUNT OF COMMERCE INTERESTED.

The reasons for the demand for an increased width and depth of channel and the amount of commerce interested are fully set forth in the letters from the Business Men's Association of Pawtucket, which will be found appended to this report.

The statements contained in these letters are believed to be substantially correct.

ESTIMATES OF THE COST OF IMPROVEMENT.

It will be observed, that the business men of Pawtucket desire a channel with a minimum width of 150 feet and 12 feet deep at mean low water, and I have prepared an estimate of the cost of such a channel extending from the deep water just above Red Bridge to a point in the natural channel where the ledge rock appears at depths less than 12 feet below mean low water. This, as before stated, is opposite Grant & Co.'s wharf, and about 750 feet below the bridge at Pawtucket. From this point to the bridge I have estimated for a channel in rock cutting 40 feet wide and to a depth of 12 feet at mean low water.

The excavation, at the expense of General Government, of a wide channel through the rock which lies between the wharves on either side of the river is probably out of the question on account of the expense, and, in my judgment, is not necessary, since the river here is very narrow. The proposed rock cutting is short, and there are on the east side, as will be observed on the plat, two natural