Sewer systems for small cities and villages

Front matter

THE UNIVERSITY w

OF ILLINOIS LIBRARY ll

SEWER SYSTEMS FOR SMALL CITIES AND VILLAGES

Preface

Of necessity, villages, towns and small cities are giving ranch attention to municipal improvement and especially to the "betterment of sanitary conditions. Of first importance in the movement is the matter of providing good drainage both for storm water and for sewage. For many reasons, this "small" hut important work very frequently falls to the lot of the young engineer, naturally not of great actual experience in this field. For him, in a way, this thesis is prepared - not as an infallible guide, but as a mere recitation of the experience of a fellow engineer in a similar situation.

So far as possible, with reference to engineering and legal matters, the endeavor has been made to secure an arrangement chronological in order. As is always the case after a task is completed, the author now sees where improvements in design and construction might have been made. Such constitutes experience.

The legal counsel in behalf of the city were Herrick and Herriok of Farmer City, Illinois, whose advice has been very helpful and who successfully defended the improvement through the Circuit and the Supreme Courts.

The author sincerely trusts that this thesis will be of some value in guiding the young engineer along the road leading to experience.

Philadelphia, Pa,, January — 1913.

Table Of Contents

CHAPTER PAGE

I— NECESSITY AND ADVANTAGES OP SEWERS 1

II— -PRELIMINARY CONSIDER AT IOII OF PROBLEM 4

Chapter I NECESSITY AND ADVANTAGES OF SEWERS Convenience and Health

During the evolution of a country district into a built-up village or city, certain physical changes take place which, though possibly not affecting the rainfall, nevertheless increase the run-off. The porous soil of the tilled field becomes the more impervious sod of the lawn. The water falling on the roofs of the buildings immediately joins that on the exposed ground surface. Sidewalks and improved roadways absorb little. Later, street pavements add to the increased amount of water which must be cared for quickly by underground drainage. In fact, drains and sewers should be laid before a street is paved.

The advance in civilization, together with the increased wealth of the nation, has brought about the desire for and the possibility of greater conveniences and comforts for both the public and the home. In the more closely built-up village, attention must be given to the purity of the drinking water. Since neighbors are not so far apart, one cannot live so much to and for himself. Unsanitary barnyards, privies and cesspools must be eliminated. To proteot the drinking water, to lessen the danger of such epidemics as typhoid fever, sewers are necessary for removing the contaminating agencies. One life, needlessly and selfishly lost, is worth many times the sewer tax levied on any single property holder. Commercial Advantages

Recent and more prolonged industrial changes, along with the growth and development of villages and towns into cities, are bringing about a commercial revolution. The nation in general has just awakened to the fact that agriculture is no longer its one principal industry. The manufacturing interests are already enormous, and manufacturing in this country is scarcely in its infancy. For various reasons, heretofore these factories have centered in the great cities. The present-day trend is away from the large centers to villages and smaller cities. The causes are not difficult to discern. Labor troubles, especially sympathetic strikes, have much to do with the change. The growth of individual business, the lack of room for expansion (except at enormous expense )} and the general unsanitary conditions in congested cities are other factors. Interstate and state commerce commissions are effecting equitable adjustments of freight rates so that it is now frequently economical and advisable to move the manufacturing plant to the crude product rather than to haul the product to the plant. Municipal taxation and the chances of political graft and extortion are less in small places. The better air, the better homes, the better sanitary conditions, the better moral surroundings—all are conducive to a better class of workman: the result is reflected in the quality of the workmanship and consequently upon the profits side of the factory ledger. The Application

Many small cities (and among the number, Farmer City, Illinois) have been quick at seeing and making provision to

reap the full benefit of their advantages in this industrial change. Rapid means of transportation now enable city business and working men to live in suburban towns. With the coming of factories and new inhabitants, there is an increase not only in local business but also in the value of real estate, both of the village or the city and the surrounding country. Increased values mean greater local wealth. Live towns, with an eye on the future, are bettering their sanitary conditions.

Chapter II PRELIMINARY CONSIDERATION OF PROBLEM Topographic and Eoonomio Situation

The first requisite towards the successful solution of any problem is a careful study of the problem itself. In designing a system of sewers the first step should be towards becoming generally familiar with the topography of the city and of so much surrounding country as might enter into the problem. Such information is of particular advantage in deciding upon the possible routes of the outlet sewer or sewers, the location of the disposal plant, and consequently in the general layout of the entire system. This knowledge oan be had only through personal inspection.

In Re Farmer City

Parmer City is located in the corn-belt of central eastern Illinois (DeWitt County) at the intersection of the Illinois Central and Big Pour (P. & E. ) railroads. On the former it is mid-way between Chicago and St. Louis; on the latter, it is similarly placed with respect to Peoria and Indianapolis. Its population, estimated at 1200 in 1910, is composed principally of retired farmers. It has two small factories, one producing Portland cement products only and the other manufacturing both cement and clay products. The city is unique in owning and successfully operating its water and electric lighting plant.

Previous to the construction of sewers, not only was it free

from debt, but it also had sufficient money in the treasury for paying the city's share of the cost of the improvement.

I

The soil of the surrounding country is fertile and productive. The farmers are prosperous. Since it is twenty-five miles from cities offering greater trade opportunities, Farmer City enjoys an unusually good local "business. Though it is a city which take3 pride in itself, nevertheless in the last twenty years, its population has increased but three hundred. The city council considered this due to the very limited opportunity for the laboring man.

With the intention of bettering the sanitary conditions of the city, of attracting factories, and of increasing population and trade, a movement was begun for improving the city. Before beginning to lay street pavements, it was rightfully decided to plan a complete system of sewers for the entire city and to put in the principal outlet and the laterals for the business and the nearby residential sections. On account of its favorable location, together with municipal light, water, sewers (now partially constructed) and pavements (proposed,), Parmer City considers herself prepared to attract prospecting manufacturing capital, especially since the United States Geological Survey and boring tests have shown that the immediate vicinity is underlaid with a fine quality of bituminous coal.

The oorporate limits of Parmer City embrace practically all of one full section of land. Seemingly, the city is located on two ridges. In reality, these ridges are merely a continuation of the adjoining level prairies indented by two pronounced stream valleys. Through the center of the city, and in an easterly direction, flows a small stream known as 'The Slough.' This ditch drains 1800 acres of prairie land. Except at flood times, it carries a very small amount of water, and in midsummer, it is often stagnant and offensively odorous. During spring floods, at John Street, it often flows 600 euMc feet per second* By a circuitous route, two and one-half miles in length, it empties into a living stream, Salt Creek, which, at its lowest stage, flows SO cubic feet per second. The latter rarely carries less than five times this amount of water. In Salt Greek, the waters from The Slough again pass through the city limits, this time flowing ?/esterly and, at the nearest place, within 1,200 feet of their first passageway. At the highest point, the ridge separating the two streams is 16 feet above the bed of The Slough and 38 feet above the bottom of Salt Greek.

Formerly a small, open, intermittent branch flowed diagonally through the town from the corner of Indiana and Washington streets to The Slough at the latter' s intersection with Plum Street. This marshy draw originally carried the flood-waters of twenty acres of city property and sixty acres of farm land. In the course of events, ordinary drain tile had supplanted the open ditch. To improve their property, the residents, especially from Green to High Streets, have filled in their yards above the surrounding natural ground level. likewise, to better the roadway, the streets in question have received similar treatment. The result was, that sudden floods, especially when the ground was frozen, piled up the water until it was often three feet deep at the corner of Water and Washington streets. The pond frequently extended not only over the adjoining lots but even three blocks beyond the city limits. The cellars and basements in adjoining dwelling houses were flooded. Unsanitary conditions, as ordinarily resulting from such floods, were augmented "by the fact that many persons had surreptitiously connected the waste pipes of their toilets and sinks to the identical string of tile which was supposed to drain these cellars and basements. The situation was made even worse and the drains rendered almost useless through a foolish attempt to dry the streets by letting the street water, with its trash and dirt, flow directly into these tile. Ordinary outdoor privy vaults were common. Investigation even disclosed the fact that old wells were in use as cesspools, And some families were making domestic use of water from the same kind of dug-wells in that same immediate vicinity!

Searching investigation will disclose the fact that similar conditions exist in most sewerless villages and cities.

In villages and small cities the volume of house sewage per city block is so small, the existing system of street drainage so poor, and the value of the taxable property so low that separate systems of sewers for house sewage and street drainage are economically impossible. In this respect Farmer City was no exception. Subsequent trenching disclosed that the streets and private property were fairly undermined with drains in which were found speoimens representing every phase in the evolution of the ordinary farm drain tile of the butt-joint variety. Guess grading, tree roots, improper usage, both by individuals and city, had rendered nearly all of these drains useless. The money invested and wasted in these unsystematically laid and maintained drains would easily have paid for the system of sewers installed.

The conditions laid down by the mayor and a committee from the council were:-

1. — That a complete system of sewers should be planned for the entire city with a possible outlay of not more than $50,000.

2. -To make possible at once the construction of a part of the same for the relief of that portion of the city imperiled by floods and to provide immediate service to the business section of the city.

5. -To intercept outside the built-up residence district, the objectionable summer flow of The Slough.

4. -To provide for the future construction of laterals on John and Plum streets north of The Slough, so that either of these streets might be paved from the business section to the railroad depots.

5. -To make possible the immediate securing of the desire! results by putting in such a portion of the entire system as might cost not more than $20,000.

6. -To plan a first class system so excellent and so inexpensive as to make it in both ways invulnerable to possible attacks in court.

As a working basis, a cursory study of the city and adjacent country was made especially to aid in determining the location of the outlet sewer. This personal inspection disclosed four possible routes :-

Route l.-A sewer intercepting The Slough at John Street,

thence directly down that street through a deep cut between

Water Street and Clinton Avenue to Salt Creek.

Route 2. -A similar line on Plum Street, one block east of the former route.

Route 3. -A like line on Main Street.

Route 4. -A sewer following the general course of The Slough to Salt Creek.

Route 1 seemed by far the most feasible. However, no statement wrs made to that effect. As a general rule, at anaphase of the work, it is inadvisable to impart information to anyone until a formal report is called for by the power in authority. If unavoidable, a project may be diplomatically and satisfactorily discussed without revealing anything. The reasons are obvious. Snap judgment is frequently proven wrong by subsequent investigation. And often, as in this case, since all four routes involved the entering upon or the taking of private property, financial reasons and local politics made it expedient to give preference to neither. Furthermore, by withholding information and plans, the early alignment of the general public for and against an improvement is prevented and opposition is weakened by being thus delayed in organizing. Reconnoissance Survey

Of every incorporated village or city, there is a map in the proper county official's office — in Illinois, the recorder's office. Especially in small places where the streets are not designated by sign boards, access to such a map is necessary to facillitate the work preliminary to an estimate. Should the city not have its own map, information sufficient for the time may be had from maps in a country atlas, a copy of which can usually "be found in the office of an attorney, a real estate agent, or newspaper. If need be, a sketoh of the map, or so much as may be needed, should be transcribed to the field book. Upon this map should be noted the names of the streets and such prominent marks as railroads, churchs, school houses, waterworks, etc., which will aid in determining the exact location in the field. Later, from a local point of view, it may be found convenient to designate a street intersection, as "Jones' Corner," etc. As a check on the map, it is advisable to pace and note distances. Subsequently all distances must be measured and the street names, etc., verified by a comparison with the map on record at the county seat. However, too much confidence must not be placed in maps of others. (See paragraph 2, page 43)If the city has a bench mark, all levels should be referenced to this datum.

As Farmer City had no bench mark, it was decided to reference all levels to a monument of the U. S. Geological Survey located on the right of way of the Big Four R. R. near its intersection with Plum Street. The elevation of this bench, as learned by a letter addressed to the Department of the interior at Washington, D. C, was 732 .456 feet above mean sea level. To systematize and to simplfy the work and to save time, a circular system of check bench-marks was established around the limits of the city on permanent objects such as hydrants, concrete

right-of-way boundary posts, etc., from which, at any place, level lines could be started and checked. Since the city was

comparatively level or evenly sloping and an estimate was desired in the shortest time possible, elevation readings were, as a rule, taken only at street and alley intersections. Exceptions to this method of procedure were made in the case of long blocks, the few abrupt breaks in contour, and the stream banks and bed of The Slough. Occasionally, readings were also taken on hydrants and other permanent objects to serve, if needed, as reference bench marks. This plan proved very helpful. Ground elevations were read to the nearest tenth of a foot. These elevations were platted on a map of the city (drawn to a scale of 1 inch 200=feet), from which blue prints were made to aid in the design.

Preliminary Estimate

To ascertain whether the improvement could be done within the financial limit and in accordance with conditions laid down by the mayor and committee from the council, a preliminary estimate was required. After a careful study of conditions, John Street was chosen as the route for the main outlet sewer for these reasons :-

l:-Though calling for a two-foot deeper cut at the deepest point, nevertheless, through shortness of route and nature of .profile, there would not be so much deep digging and the yardage of excavation would be less on this line than on any other.

2:-The outlet sewer would enter upon only one piece of private property, which was of small value; consequently, the city would be amenable to a small amount of damages, since there would be only one owner of such private property, the political "outs" could arouse less opposition to the improvement. Looking

to future, this small private property was remote from the streets, highways and residences or residence sites, and would therefore be very suitable for a sewage treatment plant such as state laws will undoubtedly soon require.

3: -The main sewer, so located would, at its upper end, intercept the objectionable summer flow of The Slough at the fartherest up-stream point possible and also would afford service to the new (then proposed) township high school. Likewise, it would care for the business section of the city. Moreover, at Water Street, a short principal lateral could be laid ?/hich would amply protect the endangered residence section from possibility of future floods.

4: -Business would not be. interfered with by construction work on John Street as would be the case on Main Street.

5: -Prom conversations with layers of drain tile, well diggers and observant inhabitants, it was learned that less sand would be encountered in the deep trenching on John Street than elsewhere and that in general the digging was better.

6:-Moreover, the route selected was shortest, cheapest and best and could consequently be more easily defended in Court.

A secondary principal outlet sewer was designed to give service at some time to that eastern part of the city beyond the top of the southern ridge. This sewer will pick up the laterals at r,rater and Center Streets and, skirting the foot of the ridge, will conduct the sewage to the outlet of the John Street main or to the future disposal plant.

In the preliminary design for the estimate, the same general method was followed as used for the final design and as described in CHAPTER IV-THE DESIGN. With the principal outlet route located, the laterals were laid out, the run-off ascertained, and the cuts, the gradients and the sizes of pipe determined. Prom a slight knowledge of trenching, a study of detailed costs in nearby cities and of bids in technical papers on work of a similar nature, the estimate was deduced. The scheme shown in part below was used to arrive at total of the various sizes of pipe and depth of trenching, upon which the cost estimate was primarily based. Since Farmer City is a country town, the members of the Council were more or less familar with farm drainage; therefore this general method of arriving at an estimate was such as they could comprehend and discuss more or less intelligently.

TABULATION OF SEWER ROUTES A1JD FEET OF PIPE REQUIRED

Feet of Sizes of Pipe and Average Depth of

Trench

On From To 8" 10" 12" 15" Etc. Etc.

Rich's'n Grove State 200 @ 5'

State Center 330 © 51

Center Lincoln 700 @ 6'

Lincoln Rich's'n Allen 350 @ 6'

Allen Grove Center 550 © 7'

Center Lincoln 670 @ 11"

Lincoln Main 650 © 9'

Etc. Etc. Etc.

Totals of pipe @ size

The average cut of all sewers except the main on John Street was eight feet. Below is shown in detail the approximation by means of which was deduced the estimated cost per lineal foot of the completed sewer. In the table, vitrified clay pipe are indicated by "V.C." and concrete pipe by "Con".

ITEMIZED APPROXIMATION OP COST PER LINEAL FOOT Size and kind Excava- Pipe in Back Teaming, Total of pipe

tion

place

Pill ing

Sheathing, Etc.

Cost

$ 0.18

$0.16

$ 0.03

$ 0.03

$0.40

0.18

0.20

0.03

0.04

0.45

0.19

0.27

0.04

0.05

0.55

0.21

0.34

0.04

0.06

0.65

0.23

0.45

0.05

0.07

0.80

0.25

0.62

0.05

0.08

1.00

0.27

0.77

0.06

0.10

1.20

0.31

0.99

0.07

0.13

1.50

See

rable 3 below.

5.00

On account of the great variations in depth, in estimating the cost, the 33-inch outlet sewer was considered in sections.

ITEMIZED ESTIMATE OF 33- INCH CONCRETE SEWER

Length of Depth of Cut Excava- Pipe in Back Teaming, Total Section tion Place Pilling Sheathing, Cost

Etc.

200'

5 .0'

$0.20

#1.25

$0.10

$0.45

$2.00

900'

11.0'

0.80

1.25

0.20

0.70

2.95

300'

16.5'

1.20

1.25

0.30

1.10

3.85

600'

21.0'

2.05

1.25

0.50

1.60

5.40

400'

24. 01

3.00

1.25

0.75

2.25

7.25

Average

Cost per

Poot for

The complete

estimate of the cost of the entire system

is given under

Tahle 4.

COMPLETE PRELIMINARY

tri a

J3S

Item in Place

Detail

Unit Cost Total Cost

8" V. G. Pipe

146001

$ 0.40 $ 5840.00

10" " "

9740'

0.45 4383.00

12" " "

5770'

0.55 3173.50

15" " "

7030'

0.65 4569.50

18" " "

2860'

0.80 2288.00

p ^ n tt rf

3370'

1.00 3370.00

870'

1.20 1044.00

310'

1.50 465.00

2400'

4.30 10320.00

Manholes

170'

30.00 5100.00

Catch Basins

170'

20.00 3400.00

Inlets

170'

15.00 2550.00

Total

.$46,503.00

Court Costs

and Lawful Expenses @10#_4, 650.30

Grand Total

$51,153.30

Based

on the

approximate prices in Tahle 4, above, and

the unit lengths in Table

6 , page 40,|l8700.00 was the estimated

cost for that portion of

the sewer to serve the business and

flooded districts and the

adjacent residence section. Since the

trenching for the clay

pipe sewers in this portion of the work

exceeded the 8-

foot average, the estimate given the council, after

a full explanation of the

matter, was $20000.00 actual cost with possibly §1000.00 additional for court costs and legal expenses. The Committee from the council decided to undertake this much of the improvement.

Chapter III LOCATION SURVEY Establishing City Datum

As previously stated, Farmer City had no "base of city levels; therefore, the first legal and engineering step toward the construction of the sewer was the establishing, by ordinance, of a city bench-mark. (See Ordinance No. 91, page 114 of Appendix.) A rust-proof pipe of brass was chosen as the bench, which was set in the walls of the City Building and referenced to a fixed point on a permanent stone window sill. The elevation of this bench-mark was computed from that of the Government monument described on page 10. To comply with legal forms and custom, the elevation of this city bench-mark was designated as zero. Nevertheless, throughout the work, since this plane was higher than some parts of the city, sea level elevations were used, so as to avoid positive and negative elevations.

To remove possible legal vulnerability, ORDINANCE No. 92, page 115 was passed, which created the office of public engineer and defined his duties. The engineer on sewer design was appoint ed to this office.

System of Lines and Levels

Since the lay-out of this part of the system which was to be immediately constructed had been fixed in the work attendant to the preliminary estimate, the matter now resolved itself into describing and measuring the sewer lines and obtaining the elevations at intervals of 100 feet, street intersections, etc., for the purpose of profiles. The same circular system of bench-marks was used which is described on page 10. Other bench-marks were located in many places on permanent objects, so that anywhere along any sewer line a correct elevation could be determined by one set-iip of the instrument. All distances were measured, but hubs were driven only at points of change in direction or at the intersection of sewer lines. Regular stations were temporarily marked by chaining pins to the top of which red flannel markers were tied. The levelman followed closely behind the tapemen. That portion of the line of the outlet sewer on private property (described by distances and angular deflections) was tied to the point of intersection of the south line of Clinton Avenue with the East Quarter Section Line of Section 28 and was referenced to the angular intersection of the sewer line with this quartersect i6n line. The southern boundary of this section, and consequently of the city limits, was not clearly defined. On determining this line, it was found that the outlet end of the sewer extended ten feet beyond the city limits. To simplify the situation from a legal point of view, the mouth of the sewer was shifted eastward and the line thereby shortened, so as to bring the entire improvement within the city limits. Field Notes

Below is given a sample page from the field notes. From force of habit, and without extra effort, the rod readings were taken to the second place, but, in general .computations were made to the nearest tenth,

STREET LI1IE WEST FROM

JOHXI W.W.S. - Inst. 5-30-08 C.S.K. - Rod.

Stn. . +

H.I.

Elev.

Remarks

B.M.

726.09

Top of Hydrant , water and John

•

723.42

= Sta. 16 + 54 John St. Line

+24.8

W. Property Line, John St.

4.95

721.28

p

6.28

719.95

Inst .

726. 23

•

6.80

719.43

In flood times water said to stand 3' deep

Troublesome Cellar of

E. Williams, Floor at 716.5

+ 57.0 -

E. Property Line Washington Street

+82.5

6.47

719.76

C.L. Water & Wash. * Sta. #0

Wash. Line

4+07.4

W. Prop. L. Wash. St.