The Board would advise that the work of designing the tanks and of preparing the areas for the disposal of the sludge be committed to an engineer of experience in matters relating to sewage disposal.

An examination of the condition of the mill pond and the character of the nuisance caused by it shows that the bottom and sides of the pond, especially near its upper end, are covered with organic matter from the sewage, and at times when these areas are uncovered the odor from them is very offensive. When the pond is full and these areas are covered with

water, it appears that the nuisance is much less serious.

In view of this condition, and of the probability that, even if the discharge of sewage into the pond should be wholly prevented at once, there would still, for a considerable time, be a serious odor from these areas when exposed, the Board would suggest that you consider the feasibility of obtaining control of the mill privilege at the outlet of the pond, and of keeping the pond full at all times.

The Board will again communicate with you with regard to this matter when the results of further investigations now being made are available.

DANVERS LUNATIC HOSPITAL. The trustees of the Danvers Lunatic Hospital applied to the Board for its advice, Sept. 27, 1895, relative to a plan for disposing of the sewage of the hospital by precipitation with chemicals, followed by filtration through a small area of coke. This application was withdrawn, Oct. 28, 1895, and afterward resubmitted, with modified plans. The Board replied to this application as follows:

BOSTON, May 7, 1896.

The State Board of Health has considered your application with reference to a proposed system of purification for the sewage of the Danvers Lunatic Hospital, the essential features of which are a precipitating tank, in which it is proposed to precipitate the solid matters of the sewage by the application of chemicals, and a filter bed composed of coke, having an area of about a quarter of an acre and a depth of three feet, through which it is proposed to filter the sewage after it passes through the precipitating tanks.

The quantity of water used for the supply of the hospital is from 100,000 to 125,000 gallons per day, and, assuming that this represents approximately the amount of sewage to be disposed of, the rate of filtration through the coke filter would be about 500,000 gallons per acre per day. The sewage from the hospital appears to be quite dilute, judging from the results of an analysis made by the Board, and if the usual percentage of organic matter should be removed by chemical precipitation, it is possible that for a time, with great care in the management of the filter,

a large percentage of the remaining organic matter would be removed from the sewage by the proposed filter; but it is probable that, in order to purify the sewage satisfactorily, the size of the filter would have to be considerably enlarged.

The disposal of the sewage of the hospital by this plan would involve a very great expense both for construction and maintenance, as compared with the disposal of the sewage on land if an area suitable for the purpose can be found within a reasonable distance of the hospital.

With a view to learning whether there is any such land in the vicinity of the hospital, the Board has caused a general examination of this territory to be made by one of its engineers, and finds that there is a considerable area of sandy land, situated on the south-westerly side of West Street, between the street and the Ipswich River, a little over half a mile from the hospital buildings, portions of which appear to be well adapted for the purification of sewage by intermittent filtration; moreover, the situation of this area is such that sewage can probably be conveyed to it by gravity at a small expense from your present sewage carriers, which are at present laid to within about 1,000 feet of this area.

In view of all the circumstances, the Board would advise that you have an investigation made, to determine the feasibility of disposing of the sewage of the institution upon this area by intermittent filtration; and the Board will, upon application, advise you further with regard to this matter when you have the results of further investigations to present.

METROPOLITAN SEWERAGE COMMISSION. An application was received from the Metropolitan Sewerage Commission, Oct. 9, 1895, under the provisions of chapter 406 of the Acts of 1895, for the approval of the Board of a system of sewage disposal for a district lying partly in the city of Boston and the towns of Milton, Hyde Park and Dedham, in the valley of the Neponset River, and for a portion of Newton and the town of Brookline lying in the valley of the Charles River. The Board replied to this application as follows:

BOSTON, Feb. 18, 1896.

The State Board of Health has considered your application with reference to a proposed system of sewage disposal for that portion of the city of Boston and the towns of Milton, Hyde Park and Dedham lying within the valley of the Neponset River, and portions of the city of Newton and the town of Brookline lying within the valley of the Charles River. The application is accompanied by a plan and profiles and a report of your engineer, giving details of the proposed scheme approved and adopted by

your Board, in accordance with a provision of chapter 406 of the Acts of 1895.

The plan provides for a main sewer from a point on Worley Street, near Weld Street, in the West Roxbury district of the city of Boston, through various streets and private lands to the bank of the Charles River, a short distance above the Brookline water works pumping station; thence in the vicinity of the right bank of the Charles River and along the left bank of Mother Brook and the Neponset River to the Dorchester intercepting sewer of the city of Boston at Central Avenue in Dorchester. The capacity of the latter sewer is limited by a section below Baker's Court in Dorchester, which has a capacity of only about 20 cubic feet per second; and it is estimated that the capacity of this sewer, if the sewage of the Neponset valley is discharged into it, will be attained about the year 1905. To provide for the disposal of the sewage after this date two methods are suggested, by either of which the sewage in the Neponset intercepting sewer would be diverted at a point on River Street, Hyde Park, about 500 feet below the Mattapan paper mill, and conveyed by gravity either to the Boston main drainage sewer at Squantum or an independent outlet at Nut Island in Quincy. With this end in view, the Neponset intercepting sewer has been designed with a capacity above the point of diversion estimated to be sufficient for the probable needs of the valley until 1930, while below this point the capacity is proportioned to that of the limiting section of the Dorchester intercepting sewer, estimated to be sufficient until 1905.

In designing the Boston main drainage system it was anticipated that the sewage from the higher portions of the district bounded by the Charles River, Mother Brook and the Neponset River could be at some future time intercepted by a "high-level" sewer and conveyed to Squantum by gravity, thus affording relief to the pumping station and tunnel when the flow of sewage shall tax their capacity; and provision was made, in the construction of the works, for the connection of such a sewer with the outfall works at Squantum and Moon Island. Your investigations indicate that a feasible route for this sewer can be found, which would intercept the proposed Neponset valley sewer at the point where its size is reduced, on River Street in Hyde Park. Your investigations also indicate that a feasible route for an intercepting sewer from this point to Nut Island may also be found. With regard to disposing of the sewage in the future by either of these methods the Board can express no opinion, with the information available at the present time, and you have verbally requested that the consideration of these matters be omitted. The Board has accordingly considered only that portion of your application which refers to the disposal of the sewage of the Neponset valley by means of the proposed sewer shown on the plan contained in the seventh annual report of your

Board, opposite page 38, which provides for the discharge of the sewage into the Dorchester intercepting sewer at Central Avenue in Dorchester.

With regard to this portion of the scheme, the Board finds that the proposed sewer will provide a satisfactory means of disposal for the sewage of the territory in the Charles and Neponset valleys which it is estimated to serve, probably until about the year 1905, if care is taken in the construction of the main sewer and tributary systems to exclude surface and ground water from the sewers so far as possible, and if the amount of manufacturing sewage is restricted by preventing the discharge into the sewer of water from manufacturing establishments that can be properly discharged into natural water courses.

The size of the proposed sewer above the point where it is expected that the sewage will be diverted at some future time appears to be sufficient to make a reasonable provision for a population as great as may be expected to be connected with this portion of the system in 1930, so far as can be judged by present indications. The size of the sewer below the point where it is expected that the sewage of the Neponset intercepter may be diverted is such as to serve the low districts in Dorchester and Milton for many years after the sewage of the upper portion of the system is diverted. The Board approves the plan of disposing of the sewage of the Neponset valley by discharging it into the Dorchester intercepting sewer of the city of Boston, but expresses no opinion as to the most appropriate method of disposal to adopt after the capacity of this sewer is reached. The increase in the amount of sewage to be disposed of by the Boston main drainage system will necessitate before long the enlargement of the reservoir capacity at Moon Island, and the necessity for enlargement will be hastened by the addition of the Neponset valley sewage.

It is understood that the sewerage systems to be connected with the Neponset valley sewer shall be constructed upon the so-called "separate" plan, and that no sewage overflows will be used in connection with the main sewer or tributary systems.

On March 18, 1896, the Metropolitan Sewerage Commission. again wrote to the Board, as follows:

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110 BOYLSTON STREET, BOSTON, March 18, 1896.

GENTLEMEN: In your reply of Feb. 18, 1896, to our application for approval of plans for sewage disposal for Neponset River valley, at the close you say: "It is understood that the sewerage system to be connected with the Neponset valley sewer shall be constructed upon the so-called separate' plan, and that no sewage overflows will be used in connection with the main sewer or tributary systems." As we are

informed and understand, you do not, by the use of the words "no sewage overflows will be used," etc., intend to prohibit or prevent the construction of such provision for temporary overflows as it would seem necessary should be provided for use in case of accident or necessity of repair of trunk sewer. Unless we hear from you to the contrary, we shall proceed to construct the main trunk sewer and approve local connections therewith, making and requiring such provision for such overflows similar to those provided and required in the Charles River and north metropolitan systems, to be used only in case of emergency.

The Board of Health replied to this letter as follows:

BOSTON, March 26, 1896.

The State Board of Health received from you, on March 18, a communication with reference to the use of sewage overflows in connection with the proposed Neponset valley sewerage system, in which you state that unless you hear from the Board to the contrary you shall proceed to construct the main trunk sewer and approve local connections therewith, making and requiring such provisions for such overflows similar to those provided and required in the Charles River valley and north metropolitan systems, to be used only in case of emergency.

The plan presented by you for an intercepting sewer for Neponset River and Mother Brook basins, including a portion of the Charles River basin, which this Board approved in its communication dated Feb. 18, 1896, did not contain any provision for sewage overflows, and no mention of sewage overflows was made in the report of your engineer submitted with the application.

Before the Board can approve a plan providing for sewage overflows, it will be necessary that you submit a plan showing the location of the proposed overflows, with a description of the proposed method of constructing and operating them.

The Sewerage Commission again wrote to the Board, April 18, 1896, as follows:

110 BOYLSTON STREET, BOSTON, April 18, 1896. GENTLEMEN:- In response to your communication of March 26, 1896, stating that a plan will be required showing the proposed overflows from the Neponset valley intercepting sewer, with a description of method of