USA > Massachusetts > Middlesex County > Newton > Town of Newton annual report 1878-1879 > Part 20
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But the quantity of tide-water which comes above Old Cambridge, is about twice as much as the ordinary flow of fresh water in the river ; so that there is three times as much water for diluting sewage, in this part of the river, (to say nothing about the tide-water below,) as if this were a fresh- water stream only.
At present, Charles river above tide-water is not materially
Report State Board of Health, 1876, p. 84.
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affected by house sewage. The slight brown tinge every where found in its water is of vegetable origin, and similar to the coloring matter of tea. The impurities. noticeable at Watertown, come almost wholly from manufacturing refuse.
Considering all the facts, I am of the opinion that with skillful management the sewage of Newton can be discharged into the river, below low-water mark, near the Arsenal, for many years to come, without much objection or just ground for complaint, aud I have no hesitation in recommending this as the most feasible plan.
It is true that the sewers will carry down considerable quantities of street mud and other solid substances, some of which may possibly be deposited in the bed of the river. But it should be remembered that the storm-water from this ter- ritory, has been carrying solid matter into the river from time immemorial, and the current has carried part of it on to the marshes and the remainder out to sea, so that there is no proof of any general shoaling of the river, since the first settlement of the country.
If, however, part of the sewage matter should settle in the river, it can be dredged up by steam power and carried by water to some suitable dumping ground, much cheaper and with much less offence than would be involved in any plan for settling in reservoirs and removal by hand labor and carts.
We have now to consider the best method of collecting the sewage, and conveying it to the outfall.
In the early discussions upon the utilization of sewage, when it was generally supposed that a mine of wealth existed in human wastes, the difficulty of separating this wealth from the great volume of water in which it was diffused was recognized, and the cry of " The rain to the rivers, the sew- age to the land," arose among enthusiastic sewage economists. This, in its entirety, is impracticable. An attempt to accom- plish it involves a double system of sewers throughout.
That such double system is rarely attempted, even in cases where the advantage would be much greater than can possi-
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bly be the case in Newton, shows that the weight of expe- rience is against this plan. It is expensive and complicated and likely to give unsatisfactory results.
The first run of street-water during a shower, contains accumulations of horse excrement, etc., and ought to be taken in with the house sewage. Any effort to separate the rain- fall from other sewage after the first run, involves numerous connections and an arrangement of separating weirs between the two systems, by which a small run of water in the rain- water system, may be turned entirely into the house system, and a large run of water in the rain-water system, may be kept entirely out of the house system. According to this plan, two lines of sewers must be laid in every street, and connected with every house, unless it is arranged for the house system to take the rainfall from the roofs and yards, which, however, will not obviate the necessity for the second system to take street-water. This double system involves great expense, both in construction and in maintenance, and it has been found practically that with the most careful supervision it is almost impossible to prevent the tapping of house drains into the rain sewers, or the rain conductors into the house sewers, either by mistake or design, especially when the sewer into which the particular drain ought not to be entered, lies nearer to the premises than the proper sewer. To whatever extent these mistakes are made, the tendency is to defeat the effort to maintain separate systems.
If it is argued that the rainfall may go off as it has always done, we have to consider that individual owners of lands in growing places, are constantly changing and improving their property, and may at any time stop the ordinary surface flow of rain-water over their lands and turn it into the streets. Such action on the part of land owners cannot be prevented, and it often changes materially the conditions under which the city drainage is to be cared for. Once turned into the street in large volume, the rain-water must be taken care of
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by sewers, because the damage which would result to prop- erty by any other course would be unbearable.
It is only where there are brook channels which may be reached by the rainfall, without passing over improved lands that it is practicable to dispense with sewers for the convey- ance of rain-water.
It appears to mne that the effort to secure a separate collec- tion of house sewage will involve, eventually at least, a com- plete double system of sewers, and that this is too expensive and unsatisfactory, on the whole, to warrant its adoption.
We come then, to a consideration of the amount of sewage to be provided for in the single system of sewers.
The most important function of sewers being to remove filth, they should be so planned as to serve this purpose in the most effectual way, so far as is compatible with their other functions. At the best, a scheme of sewerage must be a compromise between somewhat conflicting requirements. To be self-cleansing during dry weather, when the flow in the sewers is comparatively insignificant, the channels must be narrow, so as to concentrate the streams. This tends to keep the sewers small. The effort to keep down the cost of works has the same tendency.
On the other hand, the proper provision for storm-water requires large sizes. In some localities, the sewers must be large enough to take all the water coming to them even in the greatest storms ; and we have seen, that as a general rule, water which once gets into much-travelled streets must be carried away by the sewers. But in places like Newton, the water from large tracts of unoccupied land, which can con- veniently be run into the brooks, and kept out of the sewers should be so treated. As far as practicable, the brooks should be kept separate from the sewers, except to avail of brook- water occasionally during droughts, to keep the sewers clean.
The most common rule, in the best practice in this country and in Europe, is to make lateral sewers of capacities to take
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care of a rainfall of about one inch per hour, on the assump- tion that about one-half of this rain-water, or thirty cubic feet per minute per acre, will reach the sewers from ordinary city territory which is nearly level. If the ground varies materially from level, or if it is very compactly built upon, the capacities of the sewers should be suitably increased.
The carrying capacity of large branches and mains is made less than the total capacity of their feeders, by amounts depending on the differences in character and distance of the different sub-districts, in consequence of which the tributaries will seldom all run full at the same time.
Experience indicates that some parts of a system of sewers so arranged may be overcharged for a short time, perhaps once in three or four years on an average, in consequence of heavy rains on ground frozen or already saturated, rain- falls exceeding one inch per hour, etc. At such times, dam- age will result from the washing of streets, flooding of low grounds, cellars, etc. In most cases, it seems better to take the risks of this, rather than to make the sewers lar- ger, -hence, more costly and less suitable for dry-weather flow.
By properly restricting the admission of storm-water, -- correcting if need be by experience of the working of the system, as it develops year after year, - this flooding may be almost wholly avoided.
The Providence system of sewers, which was designed and in large part built from three to five years ago, and which is sometimes quoted as one of the best in existence, is based on this theory, of providing for one inch of rainfall per hour,- its main peculiarity in this respect being that the additions for steepness of surface both ways, were carefully and scien- tifically worked out. Several of these sewers have been over- flowed once or more in unusual storms, and considerable com- plaint has followed, somewhat as anticipated.
Provision even to this extent requires very costly mains for large districts, especially if the slope is small or the out-
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fall is far distant, and in such cases it becomes very important to avail of every allowable way of reducing cost.
In some cases, sewers can be allowed to overflow when running full or nearly so, thus discharging part of their con- tents at suitable points short of the outfall. The extent to which this can judiciously be done depends on local circum- stances, such as the size and strength of the stream discharged into, its proximity to houses, etc.
The intercepting sewers built some fifteen years ago for the London Main Drainage System, were designed to carry only one-quarter inch of storm-water in twenty-four hours, or about five-eighths of a cubic foot of water per minute per acre, plus the house sewage. It was estimated that in an average year there would be twelve storms which would send water to the mains faster than this, and overflows were made for discharging the excess into the Thames by the easiest routes. In several instances since the completion of these works, the excess of storm-water above the capacity of the sewers has flooded many cellars and low-lying grounds, and great complaint has been made in consequence.
The capacities of the main sewers now in process of con- struction for Boston, were fixed on the same basis as the London system ; that is, to provide for the house sewage and one-quarter inch of storm-water in twenty-four hours. But heavy rainfalls are so much more frequent here than in Lon- don, that the Boston system, when all the lateral sewers are completed and connected, will probably be overcharged some thirty times per year. This number of overflows, at the cor- responding low rate of dilution, may be tolerated in Boston, where the discharges can be made directly into the large volume of water in the harbor.
One strong reason for keeping the capacity of the mains down to the smallest limit allowable, both in London and in Boston, is that all their contents have to be raised by pumping.
But it should be remembered, in this connection, that foul
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water becomes dangerous and otherwise offensive about in proportion to the degree of pollution. Hence one principal desideratum is to secure the highest practicable rate of dilution.
In view of the objections against turning sewage into Charles river above tide-water, it is obviously desirable to include as much as practicable of our territory in the district discharging at the proposed outfall. The area which can conveniently be included in this district, is estimated approxi- mately at five thousand five hundred acres, which is some- thing less than half the total area of the city. A small area of low land near Riverside, also Lower Falls Village, Upper Falls Village, and the southerly part of the Highlands cannot be brought into this district at any reasonable cost. I esti- mate the number of inhabitants in these places, together with those outside of all the villages, at about one-fifth of the whole population of the city, -leaving about four-fifths within the drainage district of five thousand five hundred acres.
To carry all the water of ordinary storms from this district would require sewers of enormous size. And as large parts of the district are now, and will long continue to be unoccu- pied by buildings, the drainage from them may safely be allowed to flow off through the natural brooks.
As a general rule, it seems reasonable to build main sewers of such sizes as will answer for about twenty-five years to come. Present outlay for anything not needed within that time is usually injudicious, because the cost will quadruple itself at compound interest ; and after all, the work may prove useless or nearly so, owing to the impossibility of fore- seeing what will be needed so far in the future.
It is difficult to estimate with much confidence, how fast the unoccupied areas will be built upon, but I judge from the past rate of growth of the city, that there will be nearly fifty thousand inhabitants within this drainage district
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twenty-five years hence, and that about three thousand four hundred acres will be occupied to such an extent, that its drainage will be unfit to run in the natural channels.
It will not be necessary, however, to provide sewers for carrying away all the water from this area in large storms. But it will be extremely desirable to take a large part of it, because, as previously mentioned, the first run will be mixed with foul matter to such an extent as to be about as objec- tionable in the open channels as house sewage would be ; in fact, gutter-water, often appears much fouler than ordi- nary dry-weather sewage. It is also desirable to get a good run of water through the sewers at every storm, for the pur- pose of flushing them out, - the ordinary dry-weather flow being too feeble and sluggish, in many cases.
The amount of storm-water which should be taken through the sewers, will depend upon the amount of refuse produced within the district, and hence upon the population, both as to refuse matters from buildings and filth caused by travel on the streets. It should be observed, however, that Newton is almost wholly a city of residences, so that the amount of refuse to be removed is much less than it would be if the inhabitants generally remained there and worked at trades and manufacturing.
On the whole, I believe it will be best to follow the com- mon practice as to lateral and small branch sewers, i. e., to make them with capacities for thirty cubic feet per minute per acre of flat territory, with suitable allowances for steep- ness. Also to make the larger branches of various less capac- ities down to five cubic feet per minute per acre, according to circumstances ; and to make a main sewer capable of carry- ing four and one-half cubic feet per minute per acre, includ- ing the house sewage, or about fourteen thousand five hun- dred cubic feet per minute, from the area of three thousand four hundred acres.
The scheme which I recommend is intended to fulfil these
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conditions, and is shown somewhat in detail by the accom- panying plans and profiles .*
It will be advisable to provide for the future drainage of the lower part of the valley of Cheese-cake brook, and the river slope east of it, by keeping the main sewer low enough to receive a branch from this territory. This branch may enter the main near the brook, a short distance east of Jeffer- son Street. At this point, the crown of the main should be at grade 14.36 ; and starting from this, it may fall one in 1,250; which, if continued so far, would bring the crown to about grade 9.00 at the outfall. But instead of this, a short piece of the sewer next the outfall should run down much more rapidly, so as to carry the discharge below low-water mark.
I estimate that the tide at the proposed outfall is below grade 9.00 about five-sixths of the time. Spring tides rise to about grade 11.00. A sewer of eight feet six inches in diam- eter, running full and at the proposed grade, will discharge about eleven thousand five hundred cubic feet per minute, when the tide is at grade 11.00 ; about fourteen thousand nine hundred cubic feet per minute, when the tide is at grade 9.00, and more at lower stages. Considering all the facts, I believe this size, or an equivalent about eight feet wide and nine feet high, is the best to adopt.
The principal branch sewer from West Newton down to Galen Street, cannot well have a fall of more than .065 per hundred, or one in 1,538; and it seems best to make it eight and one-half feet in diameter up as far as Crafts Street, where it will receive the drainage from the south part of Newton- ville, and probably in the future, from Newton Centre.
When a large part of the three thousand four hundred acres shall have been sewered on this basis, it may occa- sionally happen that the principal branch sewers will all run full at the same time. During the short and infrequent times
* The plans and profiles here referred to are on file in the office of the City Clerk, where they may be seen.
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when this occurs, the excess of flow from the branches should be discharged into the river, by an overflow at the head of the main, as indicated on one of the plans. At such times the house sewage will be less than one per cent of the whole flow. When the whole system shall be completed, there may be several storms per year which would overfill the principal branch and main sewers if all the water were admitted to them. When this time comes, many of the inlet openings may be reduced, so as to exclude more of the storm- water, and additional brook channels or " storm-sewers" may be made as found needful. Possibly storm overflows may also be made at other places besides the head of the main. Some relief may also be obtained incidentally by the con- struction of branches needed in new streets, etc.
The construction of this system, -if the city should decide to enter upon it, - would naturally be extended over some fifteen or twenty years. Within this time, many new streets will be laid out, and other changes will be made which can- not now be foreseen ; and doubtless, some of the details now suggested may need to be altered to suit the new conditions. Probably some of the details may also be changed to advan- tage, in consequence of more full and exact information which may be obtained prior to construction. In other words, the plans indicate what seems best according to our present knowledge and our best forecasts as to the future. The locations and sizes of some sewers which seem most likely to be changed, in consequence of lapse of time and change of circumstances, are indicated on the plans by broken lines, and some locations are indicated by pencil lines only.
The streets of Newton having been laid out without ref- erence to sewerage are much less convenient therefor than they might have been ; that is, a better system of sewers could be made at much less cost if the streets had been rightly located for it. In many cases we can secure shorter and straighter routes, less depth of cutting, less rock exca- vation, etc., by leaving the streets and running through
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private lands. Usually, however, small sewers will be required in the streets so abandoned. The differences in cost of con- struction and other advantages of one scheme over another can be estimated with confidence. But the cost of right of way is a very uncertain element, and in many cases the choice between different locations would depend upon the spirit, - whether fair or extortionate, - in which the landholders meet the city. Some of the alternative routes depending on the attitude of landholders are indicated by pencil lines on plans.
It would seem to be wise for the city to secure the routes which will soon be needed for sewers, before they shall be further obstructed by buildings, etc., and generally to use all legitimate means of controlling the locations of new streets, both for convenience of drainage and in the general interest of tax-payers and the travelling public, instead of leaving them to the short-sightedness and self-interest of men whose prin- cipal object is to sell the utmost possible number of house-lots out of a given piece of land, as has often been done.
Before proceeding to construction, the quality of materials and workmanship to be secured should be carefully considered. Much of the sewer work in this country is too poor for true economy, both as to the durability and the proper working of sewers. Irregular sags in the grades, and great roughness of interior surface are very common, and they contribute largely to the formation of deposits in sewers. Cities which build poor sewers are almost sure to neglect them afterwards, so that they become reservoirs of pestilential filth, producing great quantities of offensive and poisonous gases. Practically, but few houses are well protected from the entrance of sewer gases through their soil pipes, though it is possible to do it; but even then the inhabitants suffer from the general pollu- tion of the soil and air.
These dangerous nuisances are not uncommon in New England cities; but they can be wholly avoided by good plans, good construction, and subsequent good care.
These considerations are especially important in connection
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with the large areas of flat land in Newton, where the sewers can have but slight falls.
The discharge of sewage into Charles river, even tempo- rarily, at any place above the outfall herein proposed, would be somewhat objectionable, and would be strongly opposed ; so that it seems impracticable to begin on a small scale by constructing and using any of the lateral sewers first.
The cost of the main and principal branch sewers will be a very large part of the cost of the whole system. Consider- ing the delay which may result from this, and the probability that in any case, large parts of the system will not be built for several years, -during which time prices may vary considera- bly,-it seems useless to undertake to make close estimates of the cost; but I append approximate estimates for some of the principal lines of sewers which will be needed first, sep- arating them into divisions so as to indicate the cost of reaching some of the more important points. These estimates include land damages and engineering :
1st Division. - From outfall near the arsenal, westerly across the marsh, and along the foot of the steep river bank to junction of Ward 7 branch, near Lemon's brook, main sewer eight and one-half feet in diameter, or eight feet by nine feet oval
2nd Division. - From Ward 7 branch to and through Maple Street, thence via Galen and Boyd, or Galen and Morse Streets, to Boyd's pond ; thence along the shore of the pond to Pearl Street; diameter eight and one-half feet
$175,000
3rd Division. - From Pearl Street, across lands of J. Sturgis Potter and others, and through Middle Street, so called, to Adams Street; thence through a private street and across Crafts Street to the junction of the branch from the south part of Newtonville; diameter eight and one-half feet
4th Division. - From Newtonville south branch, across private lands to Central Avenue ; thence through Turner Street to Walnut Street; diameter six feet nine inches 30,000
100,000
61,000
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5th. Division. - From Turner Street via Walnut and Watertown Streets to Brookside Avenue; sewer six feet nine inches in diameter .
(Perhaps some saving can be made in this division by crossing private grounds.)
6th Division. - From Brookside Avenue, via Water- town and Washington Streets to Waltham Street ; sewer six feet three inches by six feet nine inches . 60,000
39,000
$465,000
Respectfully,
BOSTON, November 30, 1878.
EDWARD SAWYER.
8353
8353
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