USA > Massachusetts > Norfolk County > Norwood > Norwood annual report 1900-1903 > Part 20
Note: The text from this book was generated using artificial intelligence so there may be some errors. The full pages can be found on Archive.org (link on the Part 1 page).
Part 1 | Part 2 | Part 3 | Part 4 | Part 5 | Part 6 | Part 7 | Part 8 | Part 9 | Part 10 | Part 11 | Part 12 | Part 13 | Part 14 | Part 15 | Part 16 | Part 17 | Part 18 | Part 19 | Part 20 | Part 21 | Part 22 | Part 23 | Part 24 | Part 25 | Part 26 | Part 27 | Part 28 | Part 29 | Part 30 | Part 31 | Part 32 | Part 33 | Part 34 | Part 35 | Part 36 | Part 37 | Part 38 | Part 39 | Part 40 | Part 41 | Part 42 | Part 43 | Part 44 | Part 45 | Part 46 | Part 47 | Part 48 | Part 49 | Part 50 | Part 51 | Part 52 | Part 53 | Part 54 | Part 55
The district on the north side of the above line (which may be
8
referred to as the Central District) contains about all of the territory in which sewerage is required at the present time.
The sewage of this district will be collected by an intercepting sewer laid from the corner of Clark and Williams Streets through the valley lying between Monroe and Lenox Streets to Dean Street, just east of the Walpole Branch Railroad, and from this point will flow through a main sewer to be constructed parallel with the railroad across the Neponset River to the filter beds.
The district on the south of the above line, which may be called the Hawes Brook District, has little or no need of sewer- age at present, except to provide for the wastes of Winslow's tannery upon Endicott Street. The sewage from that part of this district which is west of Walpole Street will be collected at the junction of Walpole and Endicott Streets and flow through a main sewer, through the latter street, past the tannery, across the railroad, through the field, crossing Washington Street 350 feet south of Hawes Brook, to Morse Street, thence following Morse Street to a point east of the Walpole Branch Railroad, thence running to the main sewer from the Central District and joining the same at a point near Pleasant Street.
PUMPING SECTIONS.
The remainder of the area of the town is situated at an eleva- tion so low that the sewage from it cannot be delivered by gravity to the filtration area, but must be pumped.
The area from which the sewage must be pumped is also divided into two districts. One of these, which may be desig- nated as the Pleasant Street Pumping District, comprises sub- stantially the area north of Hawes Brook, east of the Midland Railroad, the intercepting sewer of the gravity section, and south of Cross Street.
It is proposed to collect the sewage from this district in an underground reservoir on Pleasant Street near the Neponset River. From this reservoir it will be pumped into the nearest manhole in the main sewer of the gravity system. The pumping station, reservoir and pumping main will be located about as shown on the map. If this section of the sewerage system were
9
to be installed at the present time, the following pumping plant would be recommended : Two vertical submerged centrifugal pumps, with a capacity of 200 gallons per minute, each driven by a 5 H. P. gasoline or oil engine.
The estimate of cost of this station is based upon the above described plant.
It is not certain, however, that if the construction of this sec- tion is postponed for several years, as it seems likely to be, the plant described above will be the most available or economical at that time. The town may then have a municipal lighting plant, in which case electrically driven pumping machinery may prove to be the best.
At the present time and under the present conditions this plant is recommended as combining the lowest first cost with the least annual expenditure for fuel and attendance.
The pumping for many years to come will probably require but a short time each day, and, as the station is near the filter beds, the man in charge of the latter can operate the pumps. An oil or gas engine does not require a skilled engineer. It can be started in a few minutes, and may be left to run without attendance, and stopped automatically. As soon as stopped the consumption of fuel ceases. It is, therefore, a desirable type of power where the amount of work to be done is small and intermittent.
The other low lying district is in the valley of Purgatory Brook and may be called the Purgatory Brook District.
There is little or no need of sewerage in this section at pres- ent, and the following plan may be modified by existing condi- tions when the sewers are constructed. It is proposed to collect the sewage in an underground reservoir on or near Neponset Street at the low point between Pleasant and Cross Streets.
From this reservoir it is proposed to pump it through a cast iron force main to a manhole in the intercepting sewer of the Gravity Section. The pumping plant may be driven by a gas, gasoline or oil engine, by an electric motor, or that form of power which is most available and economical at the time the works for this section are installed.
:
10
The location of the sewer lines, reservoir, pumping station and. force main are indicated upon the map. ..
SEWERS.
The street sewers will be constructed with vitrified clay pipe. with "wide and deep sockets." The intercepting and main sewers will be of the same, or, if found to be cheaper, may be- . constructed of concrete. This can be ascertained when bids are received.
PUMPING MAINS.
The pumping mains which are proposed in the pumping dis- tricts will be of coated cast iron water pipe.
INVERTED SIPHON.
There will be but one inverted siphon in the entire system. This will be in Morse Street upon the main line from the Hawes Brook District, where it crosses the valley of the Neponset River .. It will be laid of coated cast iron water pipe. This inverted siphon is unavoidable. No trouble need be apprehended from it, however, as they are invariably successful when properly laid, and are in common use.
SIZES AND GRADES OF SEWERS.
In a separate system of sewerage the flow of sewage in the. " laterals," or the sewers which serve only the street in which they are laid, is small, and the size of the sewers is not designed with reference to their capacity to carry the sewage.
Their size is largely fixed by the grade at which they are laid. To secure economy of construction this grade should be approx- imately the same as that of the street surface. It has been found by experience that it is not advisable tu lay any street sewer smaller than six inches in diameter on account of stoppages, which are more liable to occur in smaller pipes. It is necessary to lay the sewers 'at so-called self-cleansing grades, that is, at. such grades that when flowing half full or more the velocity will be sufficient to carry along any substance which may enter.
The method of securing a flow of that volume in lateral sewers. will be alluded to under the head of flushing.
11
In this system no six inch sewer is proposed where the grade is less than one foot fall in one hundred feet.
Where the grade of any sewer is flatter than this, an eight inch sewer is used, except where the estimated flow is greater than its capacity.
In estimating the amount of the sewage, the future must be considered, as well as the present. As may be inferred from the preceding statement, the lateral sewers will have sufficient capac- ity for any flow which will come to them when designed to be self-cleansing.
In sewers which receive the flow from larger area, however, the amount of the flow must be carefully considered.
Three elements enter into the consideration of the amount of flow, the population, water supply and leakage into the sewers of ground water.
POPULATION.
The population of Norwood since 1875 has been as follows :
Year.
Population. 1749
Increase in 5 years.
Increase in 10 years.
1875
1880
2345
34 per cent.
1885
2922
27 4
58 per cent.
1890
3733
25 “ 66
1895
4574
23 4
1900
5480
20 "
The increase in population in the last two decades has been 58 and 47 per cent. respectively. Mr. X. H. Goodnough, the Chief Engineer of the Massachusetts State Board of Health, in a report in 1897 upon the Discharge of Sewage into Boston Harbor, esti- mated the future growth of Norwood as follows :
Year.
Population.
Percentage of Increase in 10 Years.
1900
5,540
1910
8,000
44 per cent.
1920
11,450
43 «
1930
16,250
42 “
1940
22,590
39 «
47 4 .
This estimate is, I believe, as accurate a forecast as can be made of the future population of Norwood.
12
CONSUMPTION OF WATER.
The average daily consumption of water in Norwood has been as follows since 1886 :
., Year.
Total.
Per Capita.
1886
66,600 gallons
1887
133,000
66
1889
161,000
66
1890
169,000
46 gallons
1892
169,000
66
42
1893
208,000
66
49
66
1894
220,000
50
66
1895
268,000
59
66
1896
308,000
65
66
1897
354,000
72
66
1898
405,000
66
80
1899
424,000
81
66
1900
400,000
66
73
66
The above is a large and increasing per capita consumption of water. It is possible that it may be reduced, but that this would require some radical change in the policy of the works (such as the .general introduction of meters, for instance,) is shown by the history of other works, which, with unchanged conditions, show a continually increasing per capita consumption.
Estimating the future consumption of Norwood from the past it does not seem safe to use a smaller per capita rate than 100 gallons per day for the future.
In estimating the average flow of sewage 100 gallons per day will be taken as the per capita consumption of water, and 75 per cent. of this amount as the proportion of the water supply which will find its way into the sewers.
The flow of sewage is not uniform throughout the day, nor throughout the year by months. It corresponds approximately to the draft from the water supply.
In thirteen cities and towns the average rate of draft in the different months of the year was found to be as follows, calling the average rate for the year 100 :
1888
150,000
1891
178,000
13
Month.
Per Cent. of Average Rate.
Month. Per Cent. of Average Rate.
January
87.2 per cent.
July. 123 per cent.
February
89
66 August 113.5
March 88.6
September 109.4
April 89.7
October 103
May
99.8
November
92.1
Junc
114 66
December
88.7
66
The maximum rate of draft in some water works reaches over 300 per cent. of the average rate for the year for periods of an hour or more at a time.
The records of one system that I have studied showed for several days in August that the average rate from 10 A. M. to 3 P. M. was 230 per cent. of the yearly average rate.
It is, therefore, probable that the maximum flow of sewage is at least two and one-half times the average flow. That ratio is used in estimating the maximum flow.
To repeat : The basis upon which the estimates of the required capacity of these sewers is made is an average water consumption' of 100 gallons per capita, 75 per cent. of which reaches the sewers, with the maximum flow equal to two and one-half times the average.
GROUND WATER.
The amount of ground water which will find its way into the sewers is dependent upon the nature of the ground and the con- struction of the sewers.
In clayey or impervious ground very little water will come in contact with the sewer, whereas in sandy or gravelly ground, in which the water stands above the level of the sewer, only the best of construction of the joints and manholes will prevent large quantities from entering. Freely discharging underdrains will also reduce the amount of ground water entering the sewer.
Careful construction, however, must in the main be relied upon to keep the entrance of ground water within reasonable limits. The economic importance of this matter relates more to the dis- posal of the sewage than to the size of the sewers, although its effect upon the latter is not unimportant.
14
That it is a matter of importance is shown by the fact that in some systems the flow of ground water alone is 70,000 gallons per day per mile of sewers, and that a leakage of 40,000 gallons is not at all uncommon. In fact, there are a number of systems in which the flow of ground water equals that of the sewage.
It is possible, however, to keep this flow as low as 5000 gallons per mile per day, as shown by recent experience of the works where under unfavorable conditions the measured flow of ground water did not exceed 2000 gallons per mile per day. The conditions in Norwood are such that a large flow of ground water may be expected in wet seasons unless the joints of the sewers are well made. In the construction of the sewers, there- fore, especial attention should be given to this matter.
It is believed, however, that a liberal allowance has been made in designing the sewers for ground water.
CAPACITY OF SEWERS IN THE CENTRAL DISTRICT.
The 15 inch main sewer, which is laid across the railroad from the extension of Nahatan Street to Lenox Street, receives the flow from all of the Gravity Section north of Winter Street and west of the railroad. This sewer at its flattest grade has a capacity sufficient to discharge the maximum flow from a popu- lation of 11,500 people using an average of 100 gallons of water per day per capita. It also provides for a flow of ground water in addition of 225 gallons per minute, or 300,000 gallons per day.
This 15 inch sewer is continued through Lenox Street to Plimp- ton Avenue with the same capacity.
This line and the 10 inch sewer line, which crosses the railroad at the Guild Street subway, unite in a sewer at Plimpton Avenue and flow through it to the intercepting sewer.
This intercepting sewer is 15 inches in diameter from Plimpton Avenue to Hillside Avenue, and 20 inches in diameter from there to Dean Street.
The two sections are laid at such grade that they have practi- cally the same capacity, which is sufficient to discharge the max- imum flow of sewage from a population of 17,000 people, and a flow of ground water equal to nearly 500.000 gallons per day.
15
The area tributary to this sewer comprises all of the Central Gravity Section, with the exception of the area about Chapel and Cedar Streets, and Washington Street from Dean to Cross Street, which is discharged through Dean Street into the main sewer where the latter crosses Dean Street.
From this point the main sewer from the entire Central Gravity District and the two pumping districts is 24 inches in diameter, and has a capacity equal to the maximum flow from a population of 20,000 people, and 700,000 gallons per day of ground water. This quantity of ground water is no doubt an excessive estimate, even with the whole territory laid out in streets and fully sew- ered. With the present mileage of streets it amounts to 40,000 gallons per mile per day, while it is possible to keep the leakage of ground water down to 5000 gallons per day with careful work.
It is probable that the sewers described above have an ample capacity for the next forty years at least.
On account of the uncertainties of the future it is probably unwise to provide for a greater population at the present time. On the other hand, taking into consideration the present rate of growth and the conditions of Norwood, it would be short-sighted to provide for less, especially as the sum saved by reducing the sewers one size of pipe, or from 24 to 20, and from 20 to 18 respectively, would be only about $2500.00, while the capacity as measured by the population served would be reduced from 20,000 to 12,000 people. One thousand dollars more would be saved by reducing the 15 inch sewer to 12 inch, but the popula- tion provided for would be reduced to 8500.
The main sewer from Dean Street to Pleasant Street is laid partly in embankment. For one thousand feet in length, includ- ing the crossing of the Neponset River, it will be of wrought iron, . of steel, supported upon masonry piers and boxed. The condi- tions at the location at this point are unfavorable for an embank- ment.
The bottom of the sewer will be about ten feet above the ordi- nary water level where it crosses the Neponset River. The main sewer, from its crossing at Dean Street (or Willow Street). could
16
be laid as an inverted siphon of cast iron pipe through Pleasant Street and under the Neponset River to the filter bed.' The cost of this has been estimated, and it is ascertained that an inverted siphon line, with a capacity sufficient for the next ten years only, would cost practically the same as the proposed gravity line, and that a siphon line of equal capacity would cost $7000.00 more than the proposed line.
CAPACITY OF MAIN SEWER OF HAWES BROOK DISTRICT.
This sewer, starting at the junction of Walpole and Endicott Streets, is 10 inches in diameter to Winslow's tannery, and from that point 12 inches in diameter to its junction with the main sewer from the Central District near Pleasant Street. The capacity of this line, based upon its flatted grades, is sufficient to provide for the maximum flow from a population of 5000 persons. There is also a large flow from Winslow's tannery. In a report of the Massachusetts State Board of Health upon the improvement of the Neponset River, this flow is estimated at from 20,000 to 50,000 gallons per day. Assuming that it may be increased to 100,000 gallons per day, the proposed sewer will carry it and the sewage from a population of 4000 people in addition, with a ground water flow of 110,000 gallons per day.
This is believed to be an ample provision to make at this time for this district, which is sparsely inhabited, and aside from the tannery is not now in need of sewerage.
By increasing the 12 inch sewer to 15 inch, and the 10 inch to 12 inch, at an additional cost of about $1800.00, the tannery and a population of over 8000 would be provided for.
NOTE. - The size of the 12 inch sewer from the tannery should not be reduced, even if the capacity were considered excessive, as its grade is too flat for a 10 inch sewer.
The plan as proposed provides for a total population of 24,000, divided roughly as follows: 4000 in Hawes Brook District and 20,000 in the remainder of the town. This is equal to the esti- mated population between 1940 and 1945.
It also provides for a ground water flow of 800,000 gallons, or
17
from 25,000 to 30,000 gallons per mile, based upon the total mileage of streets in town at the present time.
HOUSE SEWERS.
It is recommended that the house sewers be 5 inches in diam- eter. Branches will be laid in the street sewers at proper point with the openings closed by stoppers until the connection is made.
MANHOLES.
Manholes will be provided at every ehange of line and grade of the sewer. These manholes will provide access to the sewer for inspection and give complete control of the system.
VENTILATION.
It is proposed to provide openings in the manhole covers for the admission of air to the sewers, and it is recommended that no traps be placed upon the house sewers, thus leaving a free opening through them and the soil pipes to the point above the roofs of the houses.
FLUSHING.
It is proposed to provide flushing manholes at the head of every lateral sewer. These are the ordinary manhole with a flop gate upon the outlet to the sewer. There is also a connection with the water main which is controlled by a valve. When the sewer is to be flushed, the flop gate is closed, the valve on the water pipe opened, and the manhole allowed to fill. When full the flop gate is suddenly opened, effectively flushing the sewer. Automatic flush tanks are not recommended for this system, as they are liable to use a great deal of water, which is undesirable in Norwood, and because it is believed that with the grades of these sewers entire satisfaction will be secured with occasional hand flushing, with only a fraction of the use of water and at a mueh smaller first eost.
UNDERDRAINAGE.
Underdrains or sub-drains are frequently laid under the sewer for the purpose of lowering the water in the ground and thus improving the sanitary conditions, and also to earry away the
18
ground water which would otherwise tend to enter the sewers at every imperfection in the joints. These drains are of vitrified clay pipe, laid with open joints and embedded in broken stone or clean gravel. The flow in these drains is finally discharged into some natural water course. There are localities in Norwood where the construction of underdrains will no doubt greatly improve the conditions.
While it is impossible to determine in advance just where they will be needed, or their exact size, an estimate has been made, after securing the best available information of conditions, and a study of the ground, which it is believed will provide for underdrainage wherever it may be needed.
ROCK EXCAVATION.
While Norwood is very fortunate in most of the conditions affecting the cost of a system of sewerage, especially as relates to the discharge and disposal of the sewage, there is one condition that will very materially increase its cost. I refer to the rock or ledge which is so generally distributed throughout the streets.
Mr. Bucknam, the Superintendent of the Water Works, who has by his experience with the piping acquired an intimate knowl- edge of the location of the rock, has kindly furnished the in- formation upon which the estimates of rock are based. It cannot, of course, be expected that these estimates are more than approx- imately correct, as the sewers will not be in exactly the same location as the water piping, and will generally be deeper than the latter. It is believed, however, that they will not be exceeded.
DISPOSAL.
As stated in the recommendations, it is proposed to dispose of the sewage by sand filtration upon an area south of the Nepon- set River and east of Pleasant Street, as shown upon the map. Before this method of disposal was deeided upon, the plan of discharging the sewage into the Metropolitan System was con- sidered. The State Board of Health made an investigation of this matter in 1897, and estimated that the annual cost to Nor- wood of discharging its sewage into the Metropolitan System
19
would be from $3366.00, if the towns of Canton, Norwood, Sha- ron, Stoughton, Walpole and Westwood all came into the arrange- ment and were admitted to the District upon the same terms of assessment as those now in it, to about $7000.00, if Norwood and Canton alone went into the arrangement.
The conclusions of the Board were that it would upon the whole be more desirable for each town to purify its sewage upon land. Therefore, there seems at present but little likelihood of the Metropolitan Sewer being extended to Norwood.
Even if it were possible to connect with this system at the lowest estimate of annual assessment, namely, $3366.00, the annual expenses of disposal would far exceed the annual expenses of maintaining and operating the proposed filter beds.
I estimate that the annual cost of the maintenance of the filter beds, including the interest on the cost of land and construction, as well as depreciation, repair and operation, will not exceed $2000.00 per year for many years.
It is unnecessary to compare at length the proposed system with " Bacterial Treatment," since it is well established that when sand or gravel can be found in place, the cost of construc- tion of a plant for bacterial treatment is very much in excess of that of the construction of sand filter beds, and unless their loca- tion will save in the cost of main sewers or of pumping, that nothing can be gained by the adoption of this system.
When placed in a location that would be satisfactory to the town and approved by the State Board of Health, the first cost of the main sewers would be fully as great as with the proposed system, and the conditions in regard to pumping would not be changed.
LOCATION OF FILTRATION AREA.
Other locations than the one proposed were considered. There is but one other, however, that would receive the sewage by gravity. This area is east of Pleasant Street and north of Dean Street, and appears promising from a superficial examination. An examination of the land was made by digging test pits. The water was found much nearer the surface than in the area pro-
20
posed, and it can be lowered very little by underdraining, unless the brook which runs around the north and east sides of the land is lowered as far as the Neponset River.
After the loam is removed there will be only a depth of gravel above the water of about four feet. It could perhaps be devel- oped into a satisfactory field, but at a much greater expense for construction than the proposed area. Besides this it is much nearer the thickly settled part of the town.
The area proposed is very favorable for the purpose. It is composed of coarse sand and gravel, the ground water is from 8 to 10 feet below the surface, and very little underdraining will be required. It is a comparatively level area which will not require much grading after the loam is removed to form it into beds.
There is an ample area for future needs. About thirty-five acres have been laid out on the plan, and more land is available if required.
AREA REQUIRED AT PRESENT.
The area which must be prepared will depend upon how large a part of the town is sewered. If sewers are to be laid in all of the streets in which water pipes are now laid, and if all of the houses were to be connected, the flow of sewage would prob- ably be equal to 75 per cent. of the water supply, or based upon tlie consumption of 1897, about 320,000 gallons per day, and a certain amount of ground water which, with careful construction, should not exceed 10,000 gallons per mile, or perhaps 200,000 gallons per day; in addition to this a possible 100,000 gallons from the tanneries, making a total of about 600,000 per day, wliich would require about eight acres for its disposal. This would be at the rate of 75,000 gallons per acre per day, which is a reason- able estimate for filter beds composed of material of the character found here.
Need help finding more records? Try our genealogical records directory which has more than 1 million sources to help you more easily locate the available records.