USA > Massachusetts > Middlesex County > Newton > Town of Newton annual report 1879-1880 > Part 19
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APPLICATION TO LAND.
The application of water-carried sewage to land, by irriga- tion or filtration has never been made on a large scale in this country ; but sewage irrigation has been thoroughly tried for about twenty-five years in England, where it has been more extensively employed than the precipitation processes ; and the Craigentinny and other meadows near Edinburg have been irrigated with sewage from that city for about one hun- dred and twenty years.
Strenuous efforts have been made to secure the best sani- tary results by this process and at the same time to make it profitable, or at least self-supporting. It was believed that sewage contained fertilizing elements of great value which, instead of being made the means of dangerous pollution of rivers and harbors, might be utilized by applying the sewage to land.
But many of the difficulties were unforeseen or under- rated ; and although this process is capable of giving better sanitary results than the precipitation processes, extended trials by many cities and towns in England seem to show that, commercially, it is a failure.
In an agricultural view, however, considerable success has
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attended the application of sewage to some of the coarser grasses and vegetables which absorb large quantities of wa- ter. The English "Local Government Board" states that Italian rye-grass seems to be the most advantageous crop for this purpose, "as it absorbs the largest quantity of sewage, occupies the soil so as to choke down weeds, comes early into market in the spring, (February 12, in one instance,) con- tinues through the summer and autumn, bearing from five to seven cuttings in the year, and producing from thirty to fifty tons of wholesome grass upon each acre. The area placed under this crop must, however, have reference to local means of consumption, as the young grass will not keep nor bear long carriage. It is most profitable for feeding to milch cows. A dairy and sewage farm should, therefor, whenever practi- cable, be associated. In a dry and warm summer, good hay may be made which will be sweet and wholesome." In one instance, in 1876, forty-five tons of hay were made from one cutting of eighteen acres of rye-grass.
In India, Spain, Southern France, and Northern Italy, irri- gation on a large scale has proved successful, both financially and agriculturally. But great allowance must be made for difference of circumstances. These countries have torrid cli- mates and thirsty soils. In England and the United States the conditions are different. Hence there is great force in the statement of Prof. Way, as an argument for the system, agriculturally and commercially, in India, and against it in England and the United States: " Under given conditions the sewage is valuable merely as water, and under other con- ditions the water is so objectionable that you would rather lose the manure than be obliged to have the water."
For this system a suitable tract of land must be obtained by purchase or lease. The conditions to secure the best re- sults are numerous. It should lie so low that the sewage will reach it by gravitation, or the process of pumping must be resorted to. It should be of sufficient area for present and increasing future demands ; and it should have a light
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porous soil, either naturally or artificially under-drained. It should not be so near the town as to be a nuisance to the in- habitants, nor so distant as to greatly increase the expense of conveying the sewage-say one to two miles away - and the direction of the prevailing winds should also be consid- ered. It should be skillfully laid out for its intended pur- pose, and thereafter managed with unremitting skill and care.
Where the principal aim has been to get large agricultural results from the sewage, in the best English practice, it has been applied at the average rate of about three thousand United States gallons per day per acre.
As the effort to make sewage irrigation profitable has gen- erally failed, and it is difficult in many places to obtain a suf- ficient area of land for the purpose, a new plan for the puri- fication of sewage by its application to land, suggested by Dr. Frankland, and called "Intermittent Downward Filtra- tion," has been tried in several places.
This plan undertakes to purify the sewage of about one thousand persons on one acre of land, or ten times as much as is ordinarily provided for by an acre in broad irrigation. But so far as I know, it has not been tried alone at any place permanently. At Merthyr Tydfil, in the south of Wales, this plan was followed for a few months while the irrigation fields were preparing ; but there, as at Kendal and Abingdon, in England, the ordinary use of the filtration areas is in com- bination with broad irrigation. The three places above- named are the only prominent ones where the scheme is now in operation, Mr. Bailey Denton, the engineer who planned the works for each of these places, has recently presented the works at Abingdon, which were the last to be finished and which have now been in operation about a year, as a model for economy and "a favorable instance of intermittent filtra- tion combined with surface irrigation."
In intermittent downward filtration the successive filling of the soil with air and then with sewage, is relied upon to
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bring the particles of sewage into minute contact with parti- cles of air so that the putrescible matters shall be oxidized and destroyed. This, however, is but a systematic develop- ment of a process which goes on, to a considerable extent, in ordinary irrigation.
Abingdon " has a population of a little above six thousand, and a ratable value of about £14,750. The land selected for the cleansing of the sewage, and purchased by the urban authority, is distant half a mile from the town."
Mr. Denton says, " thirty-four acres of land have been pre- pared," by under-draining, grading, etc., "six and one-half for intermittent filtration, and twenty-seven and one-half for sur- face irrigation, and the total outlay, including delivering con- duit (pipes) as well as chambers and distributing earth car- riers, cart roads, barrow paths, and fencing, wages of clerk of works, and charges of engineer, has not exceeded £2,550, or an average of £75 per acre. The cost of preparing the land for intermittent downward filtration did not reach ££85 per acre, while that of preparing it for surface irrigation cost over £70 per acre, including in each case a proper proportion of attendant charges. The soil of Abingdon is not more suita- ble than that of Merthyr and Kendal, yet it will be seen that the actual cost is only about one-third of that represented in the report referred to as the case at Kendal."
If we assume that it is proper now to provide works for Newton which may in the future be readily extended so as to be suitable for a population of forty thousand, it would be needful to obtain an area of about four hundred acres on which to purify the sewage by broad irrigation. On this area some provision should be made to purify the sewage while it is not needed by the crops. For this purpose, filtration areas may be constructed, or " waste land " set apart, or reservoirs built to receive the flow when it cannot otherwise be dis- posed of.
If it were possible to dispose of the sewage by filtration areas alone, a much less area than that above given would
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suffice. The estimate that the sewage from one thousand persons can be disposed of upon one acre of land is made by the friends of this plan. The experience obtained at Mer- thyr Tydfil indicates that under ordinary circumstances the sewage of five hundred persons would be all that could be disposed of upon an acre, for a series of years, without chok- ing the land. To be on the safe side, therefore, it would be necessary to provide eighty acres for filtration per se.
I do not know of any suitable tract of even eighty acres, in or near Newton, whose use for this purpose would be allowa- ble, and where the sewage could be delivered without pumping.
Judging from the experience abroad, which has been very extensive and decisive, we must dismiss from our minds all idea of obtaining a profit from sewage farming.
In Newton the dry-weather sewage, including subsoil- water which will leak into the sewers, will probably amount to at least seventy-five gallons per day, or one hundred and fourteen tons per year, for each inhabitant in the sewered districts. The fertilizing elements in the total excreta of an average individual, per annum, have been estimated by European chemists as follows : -
Ammonia, 10 to 122 pounds, say 11 pounds.
Phosphoric acid, „, 25
Potash,
1}
The value, in Boston, of the above in a crude and impure condition fit for agricultural use only, as in guano or bone dust, may be a little over $2.00. Distributing this through one hundred and fourteen tons of sewage-water gives less than two cents' worth of manure to a ton of water ; and this is a maximum estimate, as the rate of dilution will probably be greater than here reckoned in dry weather, and certainly much larger in wet weather. This view is sustained by the analysis of the sewage of Boston and Worcester made for the State Board of Health. By these examinations it was found that the fertilizing matters in a ton of the dry-weather sewage of Boston, compared with fertilizers sold in the mar-
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ket, were worth about one cent, and in the sewage of Wor- cester about seven-eighths of a cent.
Small as the value of sewage is thus seen to be, it cannot all be made available to the growing crops. Under the care- ful and remarkably successful management of Mr. Hope at Romford, about one-third of the nitrogen combined in the ammonia of the sewage has been availed of by the crop, and under other circumstances nearly seventy per cent of the nitrogen has been found escaping in the effluent-water.
The utilization of sewage in this country, on a large scale, is quite untried, and under the different circumstances exist- ing here new difficulties are likely. to arise. It is quite clear that, for the sake of economy, the sewage for Newton should be discharged into the tidal portion of Charles River, if it is found to be practicable to do this without making a nuisance.
DISCHARGE DIRECTLY OR INDIRECTLY INTO THE SEA.
Probably forty-nine fiftieths of the water-carried sewage of the civilized world is disposed of in this way.
The objection often made that this method wastes valuable manures, is shown by the facts above quoted to have but little weight.
The objections on the score of the fouling of the waters and filling up the channels of rivers and harbors, are of more or less importance, depending on the circumstances in each particular case, and chiefly on the amount of sewage matter comparative to the volumn and strength of the current of water into which it is discharged.
It was supposed that arrangements might be made at some future time, for discharging our ordinary dry-weather sewage into an extension of the proposed Boston main drainage, at some point near the Watertown Arsenal, and discharging into Charles river only when the main sewer should be over- filled during storm. The Boston Sewerage Commissioners of 1875, proposed to start east from Cottage Farm, with a main
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drain nine feet in diameter, and having its crown at grade eight ; that is, eight feet above mean low tide.
If a sewer of something near this size should be extended up to North Beacon Street opposite the Arsenal, rising one in twenty-five hundred, it would be practicable for us to unite with it.
But the present plan, as set forth in the Report on Improved Sewerage, July, 1877, is materially different. It provides for sewage from places west of Cottage Farm, as follows :
From Waltham, 1.81 cubic feet per second= 108.6 cubic feet per minute.
Watertown, 1.81
" " ,, =108.6
= 484.8
" =1628.4 ",
" "
Newton, 8.08
"
Brighton, 27.14
A sewer thirty inches in diameter, will discharge the amount above allowed for from Waltham, Watertown, and Newton, viz., seven hundred and two cubic feet per minute, even at the low velocity of 2.4 feet per second, which is about the slowest that is sufficient to prevent the accumulation of deposits.
Sewers of the small sizes suitable for this scheme require so much fall in order to make them self-cleansing, that they could not drain any territory on the plain west of Newton- ville, nor any of the river slope in the vicinity of the North Village, unless the sewage were raised by pumping ; and the capacity proposed would be only a small fraction of what is desirable even for the limited territory which they could reach by gravitation in Wards 1, 2, and 7.
Further, the Boston sewer will probably not be extended up to the vicinity of the Arsenal for many years to come. In the distant future, arrangements may, perhaps, be made for discharging part of the dry-weather sewage of Newton into it. It is obvious then that the Boston system cannot offer any adequate provision for our wants, and is not entitled to any further notice or consideration.
We can estimate with confidence what effects will be pro- duced by the discharge of the sewage of Newton into Charles
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river opposite the Arsenal, from an examination of the actual effects in many similar cases in this country and in Europe.
The quantity of water flowing in a stream at different stages, can be estimated approximately from the area and character of the territory draining into it, the rainfall, etc.
Substantially all the pollutions of streams come from the inhabitants and businesses which send their refuse directly into them, either through sewers or by surface drainage. Hence, most rural and village populations should be left out of account in an enquiry of this kind, as not contributing appreciably to the pollution of any stream.
In this connection, it is important to observe that much the larger part of the sewage nuisances in the civilized world are produced by refuse from manufacturing operations. It is true that there are many local nuisances, at outfalls of ordi- nary sewage ; but most of them might have been prevented by better arrangements. There are also cases where small brooks are badly polluted in running through dirty villages. But the cases where rivers, even of the smallest size, receive domestic sewage enough to make any nuisance after it is once mixed with the whole volume of the stream, are rare. The Blackstone river below Worcester is probably the only one in this class in New England ; and this case is, perhaps, the most instructive one that can be referred to in considering the discharge of the Newton sewage into Charles river.
The drainage area of Blackstone river, down to the outfall of the Worcester sewers, is about fifty-four square miles. The city has about fifty thousand inhabitants, of whom about forty thousand live in houses connected with the sewers. There is also rather a large inflow of manufacturing refuse, especially from woolen mills.
The result is, that the stream is polluted to a highly- objectionable extent. As it flows down the valley towards Pawtucket, it furnishes power for an immense amount of manufacturing, and it receives large quantities of filth from the mills and houses ; but it receives good water from its trib-
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utaries at a much more rapid rate. At Farmunsville, about ten miles below Worcester, the water is still bad; but the dilu- tion and other natural purifying agencies render the water tolerably good before it reaches Blackstone village, some fif- teen miles further down-stream; so that chemical analysis fails to detect any evidence of impurity sufficient to condemn the water at that place as unfit for domestic or any other use .*
The drainage area down to Farmunsville, is estimated at one hundred and thirty-eight square miles, - down to Blackstone at two hundred and seventy-six square miles ; and the popula- tions of the cities, villages, etc., now sewering into the river above these places respectively, is estimated at fifty-one thou- sand and fifty-five thousand one hundred.
At Lonsdale, the river water has been used until recently, for all operations in the bleaching of the finest muslins.
Similar comparisons in regard to many other. streams give like results, - allowances being made as well as practicable for differences in manufacturing refuse, - but it would take too much space to report them here.
I estimate the drainage area of Charles river down to the Watertown Arsenal at two hundred and eighty nine square miles. But one-third of the water down to Newton Upper Falls is diverted through Mother brook. Deducting seventy- three square miles on this account, we have two hundred and sixteen square miles as the area, contributing fresh water at the Arsenal.
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 me 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.
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