CITY OF BOSTON.

OFFICE OF CITY ENGINEER, CITY HALL.

To the Honorable City Council:

BOSTON, January 15, 1871.

I have the honor to present, in compliance with the sixth section of the ordinance relating to the City Engineer's Department, the following report, viz:

Statement of expenses of Department as paid from the department appropriation :

Balance of appropriation for 1869–70, ex

pended from January to May, 1870.

Amount of appropriation for 1870–71.

$3,452 88

15,000 00

The following statement shows the amounts paid since January 1, 1870, for engineering, from special appropriations :

The number of persons employed and paid from the department appropriation was on the 1st of January, 1870 (including the City Engineer)

The present number is

The Chestnut Hill party, on the 1st of January numbered

13

17

5

One of the assistants was transferred to the surveys for extension of the water works in Dorchester in May; but during a portion of the months of June, August, September and October, was recalled to Chestnut Hill.

On the 10th of November, the Chestnut Hill party was disbanded, — the last pay-roll being made up to that date. Two of the party remain connected with the department. The Resident Engineer, Henry M. Wightman, Esq., holds the position of Assistant City Engineer, and W. F. Learned, Esq., has the supervision of the extensions of the water works in Roxbury and Dorchester.

The following statement exhibits the operations of the department during the past year, and such general information relating to the various works and structures finished and in progress, as I have thought would be of interest, and comply with the provision of the ordinance relative to this report.

WATER WORKS.

Chestnut Hill Reservoir.

This great work, which has so largely exceeded in magnitude and cost the original designs and estimates, was so far completed on the 25th of October last as to be ready for the reception of water in the lower, or, as it is now called, the "Bradlee Basin." The engineering operations connected with this work, and extending over a period of seven years may, it seems to me, be appropriately recorded and described in this report, and be found of sufficient interest to warrant the occupation of the required space.

Surveys for a suitable site for this reservoir were made in 1863, and in November of that year three plans were submitted

to the Water Board. The first was a plan for a reservoir on the southerly side of the Woonsocket division of the Boston, Hartford and Erie railroad; the second was a plan of the site of the present Lawrence basin, and the third was a plan of the present Bradlee basin, but only included the portion on the northerly side of Beacon street, which then divided what is now the Bradlee basin. To this last plan was afterwards added the other portion of this basin, which was on the southerly side of Beacon street.

By the first plan a water area of but forty-one acres could be obtained, and that only by building a dam parallel to and adjoining the railroad, and this dam would, at the easterly end, have been twenty-four feet above the track, and the foundation for nearly the entire length of the dam was of the worst description, being of quicksand. By the second plan the water area was forty-four acres, but the depth of water would have been but twelve feet, which is not sufficient to prevent the growth of subaqueous vegetation. An excavation of five feet in depth, over nearly the whole extent of this reservoir, was necessary, and this was considered and afterwards proved to be a very expensive work.

By the third plan a water area of fifty-two and one-half acres could be obtained on the northerly side of Beacon street, and on the southerly side, an area of forty-one and one-half acres, the two forming a basin ninety-four acres in extent; this third plan was the one adopted by the Water Board upon my recommendation.

During the following year but little was done by this department in connection with the reservoir, with the exception of some further rough surveys and approximate estimates of the cost of doing the work.

In 1865, the City Council having made in 1864 an appropriation for the purchase of land for a site for the reservoir, and having procured an act of the legislature authorizing the