Engineering operations in redeeming overflowed lands

Introduction

I DESCRIPTION OF THE DISTRICT 1

II HISTORY OF THE ENTERPRISE 2

III SUCCESSIVE LEGAL STEPS REQUIRED 3

IV TOPOGRAPHIC CONDITIONS 5

V SURVEYS

1. Preliminary Surveys 6

2. Topographic Surveys 6

3. Location Surveys 8

VI DESIGN OF LEVEE 9

VII DESIGN OF DITCHES 12

VIII DESIGN OF PUIiP PLANT . ' 15

IX SPECIFICATIONS 18

X ESTIMATE OF COST 18

XI CONSTRUCTION OF DITCHES AND LEVEES 19

XII MAINTENANCE AND OPERATION OF PUMPING PLANT 21

XIII TOTAL COST

1. Construction 23

2. Operation 24

XIV ECONOMIC RESULTS 25

Appendix

SPECIFICATIONS FOR LEVEE 27

SPECIFICATIONS FOR DITCH 42

SPECIFICATIONS FOR PUMP PLANT 53

ILLUSTRATIONS

MAP OF DISTRICT

PHOTOGRAPHS

Levee

Dredging Ditch

Boilers

Placing Dumps

Digging Suotion Bay-

Suction Bay-

Discharge Bay-

Pump Plant

Interior of Pump Plant

Ditching Machine

I

INTRODUCTION.

AH along the Mississippi and some of its principal tributaries are many large areas of land which are frequently covered with water during the spring floods. The United States Government has built levees in some localities to keep the rivers in their channels, and in many cases the land owners have grouped tnemselves togetner to form drainage districts and build other levees and drainage works for the reclamation of their lands. The engineering problems concerning the construction of these levees and the drainage of these lands by ditches and pumping will be described in this thesis.

To illustrate these problems the Louisa-Des Moines Drainage District No. 4, in the State of Iowa, has been chosen.

I. DESCRIPTION OF THE DISTRICT.

The Louisa-Des Moines Drainage District No. 4 is located on the Mississippi River about eighteen miles above Burlington, Iowa, directly across the river from Keithsburg, Illinois. It is bounded on the north by the Iowa River, on the east by the Mississippi River, and on the west by the Iowa River and the bluffs west of the Mississippi River. The southern boundary is an arbitrary line established at the time of drawing up the petition. The district contains about 16,000 acres, and is about seven and a half miles in length and three and a half miles in width.

During the years 1892-96 the United States Government completed a levee for river improvement which extends from the

— — bluffs along the south side of the Iowa River to its mouth , thence down the Mississippi River to the mouth of Flint Creek, thence to the bluffs along the Mississippi River, enclosing an area of 44,000 acres. The Louisa-Des Moines District is located in the northern portion of the area enclosed by this levee.

South of this district and adjoining it is the Des Moines County Drainage District No.l, which includes the remainder of the area enclosed by the levee.

The Village of Oakville is located in the west central part of the Louisa-Des Moines Drainage District; but with some surrounding land is not subject to assessment, because previously organized as a separate drainage district.

II. UISTURY OF THE ENTERPRISE.

The petition for the organization of the district, signed by twenty-five free-holders of the state, was filed on June 20, 1907. Mr. J. A. Schreiner was appointed engineer for

the district on October 16, 1907; and his report was adopted

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in the early part of May of the same year. In September, 1908, Mr. Jacob A. Harman of Peoria, Illinois, was appointed engineer of construction. During the summer of the following year a complete topographic survey was made for the purpose of assessment. The first call for bids, that of tne ditch work, was issued on November 27, 1908; and soon afterwards bids were asked for the work on the pumping station. The first pump was put into operation on May 11, 1909, and the second on June first, 1909, altho even at the later date the building was completed only as far as the foundations. The pumping plant was completed during the month of August, 1911.

III. SUCCESSIVE LEGAL STEPS REQUIRED.

Altho not directly connected with the engineering operations, the engineer must have a thorough knowledge of the drains'1 1 L

age laws of the state in which he is working. These laws differ widely in the various states. The following is a synopsis of the drainage laws of the state of Iowa, under which the Louisa- Des Moines Drainage District was organized.

1. Filling petition for organization with bond to cover costs if not organized.

2. Supervisors appoint engineer to make preliminary

report.

3. Engineer's report filed, with plans and recommendations.

4. Supervisors examine the report of the engineer including plans and recommendations. If the engineer recommends the organization of the district, the supervisors either approve or modify his report or appoint some other engineer to make a further report.

5. teen the plans have been approved by the supervisors, the land owners are notified.

6. The land owners are given a hearing before the supervisors.

7. If claims for damages are filed, the supervisors appoint three appraisors of damages.

8. The appraisors' report is filed with the County Auditor, and notice is given for a hearing before the supervisors.

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9. The supervisors consider the damages, the cost of improvement, and the benefits; and declare either for or against the organization of the district.

10. After the organization of the district, the supervisors appoint an engineer, who makes a complete topographic survey of the district. The purpose of this survey is to determine the amount of benefit derived, and also for use in the design of the ditches and levees.

11. Bids are received and the contracts awarded.

12. The commissioners are appointed by the supervisors to make the assessment of benefits and spread the tax for the amount of money required for construction, incidental expenses and damages.

13. The commissioners make their report to the supervisors. The County Auditor gives notice of date when objections against the assessment roll may be made.

14. The supervisors hear the objections to the assessment roll and either confirm or change it.

15. Any objection to the assessment may be appealed to the Circuit Court.

16. The supervisors may divide the assessment into installments payable over a period of nine years, and sell bonds bearing not to exceed six percent interest, in anticipation of the collection of the taxes.

17. After the awarding of the contracts, and pending the collection of the money from the taxes or sale of bonds, the County Auditor may issue interest bearing warrants on the District to be paid out of the future funds, for construction and other expenses. The construction work is usually begun before the bonds are sold or the taxes collected, but may be deferred until the funds are in the treasury.

18. The collection of the drainage tax is carried out thru the regular tax levying and collecting offices of the county, and the funds are held by the County Treasurer until paid out on warrants issued by the County Auditor, on order of the Eoard of Supervisors, which orders are based on estimates of the engineer.

IV. TOPOGRAPHIC CONDITIONS.

Before the Government levee was built the greater part of the District was covered with water when the spring floods came down the Mississippi and Iowa Rivers; but when the rivers went down the land was partially drained by a net work of sloughs. During the construction of the levee automatic flapvalves were placed in it at the mouth of each of the sloughs.

]0hen the river was at low-water stage, the water from the District was only partially drained through the valves; but during high water these sloughs formed large reservoirs in which the water collected and remained until the river went down to a low stage. In the spring the sloughs were so full that there was no surface drainage; and hence the land was wet, soggy, and unfit for tillage.

To drain these reserviors it was necessary to collect the water at one or more central points, and pump it over the levee. By deepening some of the sloughs and constructing connecting ditches, it was possible to bring the drainage water of the entire District to the intersection of Iowa Slough with the Government levee, which is at the extreme south end. The pumpyfi'

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* ing plant was placed at this point.

V. SURVEYS.

After the organization of the district it is the duty of the engineer to obtain data on which to base estimates, and to design the drainage system. These data are obtained by surveys made either by the engineer after organization or at some previous date. The surveys for this work can be placed in three groups, namely., preliminary surveys, topographic surveys, and location surveys. These will be discussed under separate heads.

PRELIMINARY SURVEYS. The preliminary survey is to determine the advisability of the proposed drainage district, to develop preliminary plans, and for use in estimating the cost. The thoroughness of the survey is usually determined by the amount of money that the interested parties are willing to appropriate. The ideal survey would be a complete topographic survey made by the stadia method; but unless this method is required by law, as in the state of Missouri, it is very seldom used on account of its high cost.

The method used in a great many cases, and the one used in the District under consideration, is that of running levels over the routes which appear to be most feasible for the proposed ditches, and taking soundings in the lakes and sloughs. This method permits a fairly accurate estimate of the cost of the undertaking and a determination of the feasibility of the project.

TOPOGRAPHIC SURVEYS. The laws of Iowa require, for assessment purposes, that levels be taken on each forty-acre tract and soundings be taken in all lakes and sloughs in the district. The most common way of obtaining these data is to run levels on the section and quarter-section lines, and to take the depths of sloughs enroute.

In the Louisa-Des Moines Drainage District, however, a complete topographic survey was made under the direction of Mr. Jacob A. Harman, who had been appointed engineer of construction. This survey was carried on by the regular stadia methods, a base line being run from north to south thru the district, and circuits being run from it. In the open country the circuits started from the base line, followed a section line nearly to the boundary of the District, thence about parallel to the base line to the next quarter section line, and thence back to the base line. The instrument stations were placed about six hundred feet apart, one rodman being sent out about twelve hundred feet on each side of a station, and shots being taken at intervals of about three hundred feet. All buildings, fences, cultivated areas, sloughs, lakes, ditches, and depressions were taken with great detail.

In the wooded country the progress was much slower, and it was necessary to resort to different methods. here instead of running the circuits in nearly straight lines as was done in the open country, the course of the larger sloughs was followed. This method saved the cutting of a great deal of brush and gave the location of the sloughs accurately. Lines were cleared in several directions from each station, and enough shots were taken to cover the ground thoroughly.

Somewhere within a space of five or six hundred feet

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frora the bank of the river is a ridge, usually high enough above the surrounding country to make the location of the levee on it advantageous from the standpoint of construction. For this reason topography is taken with great detail for some distance back along the shore of the river.

In this type of work where speed and economy go hand in hand, it was found that the party which best served the purposes consisted of five men, a topographer, who was chief of party, an instrument man, and three rodmen. The topographer carried a sketch board about two and a half feet long and one and a half feet wide, hung about his neck, on which he made freehand sketches on sheets of paper eight and one half by eleven inches. This method was found to be much more satisfactory than the old method of making sketches in the note books, on account of the fact that the sketches could be made in more detail, and in platting up the notes no time was lost in deciphering the sketches. In wooded country where the work required the cutting of a great deal of brush, one or two extra rodmen were sometimes used, the rodmen cutting their own lines.

LOCATION SURVEY. The location survey is made after the plans have been adopted by the supervisors or the commissioners, as the case may be. For the levee location the line is run, and the center and slope stakes are set every hundred feet. Levels are taken at every station so that the exact yardage may be computed. In level country, in locating the ditches center-line stakes are the only ones set. Levels are taken as in the levee location. In rough country slope stakes also are set. In open country it was found that a three-man party was the most economical. The party consisted of a chief, who ran the instrument, and two rodmen; but in the swamps or where the country was heavily wooded, it was best to have enough axemen to keep a line cleared so that the instrument men could proceed without delay.

During the course of construction, surveys are made each month to determine the amount of work done by the contractors on the levees and ditches. These surveys are made by taking cross-sections at every station. From these cross-section notes estimates are made of the month’s progress. The contractors are paid from these estimates, a certain percent being retained each month to be paid when the undertaking has been completed.

VI. DESIGN OF LEVEE.

The principal factor to be considered in the design of a levee are economy of construction and maintenance, permanence of structure, and suitability to form a part of future construction. The last consideration is important, since the increase in the height of the river bed caused by the gradual deposit of sediment makes necessary a future increase in the height of the levee; and therefore great saving will result when future construction can be made without radical change in the original levee .

The design should follow some general plan, and should be based on the principles underlying the flow of rivers. A thorough study of the stream is necessary, the places where the erosion occurs, how it is occasioned, the nature of the banks, their height, and the material composing them. Angles should be avoided as much as possible; but where a change of direction curve as is consistent with good design. The line oi' the levee should as i'ar as practicable follow the bank of the river; but consideration should be given to a high and firm foundation, and the line should be selected with this continually in view.

The cross section of a levee will vary with the conditions to be met in that particular locality, that is, the character of the foundation, the nature of the material of which the levee is to be constructed, and the exposure to wind and waves. The more usual dimensions are 8 to 10 feet on top, altho some are as narrow as 3 feet, and a "combined" slope of five or six to one.

If it is necessary to make the levee extremely high, what is known as a banquette is constructed on the rear face. A banquette is nothing more nor less than a bench or terrace which increases the width of the lower portion of the levee, and the stability of the whole. The object of the banquette is to keep the levee from sloughing off when saturated by water, which it does by keeping the surface of saturation well within the embankment. The bench is usually about twenty feet wide and has a rear slope of something less than that on the river side.

Theoretically, for a cross-section of a levee of equal strength in all parts, side slopes of one to one are all that are required, but in practice this must be modified according to the angle of repose of the material. Steeper slopes than one to three cause the material on the landward side to slip, and on the river side the material is too easily washed away.

The standard sections used on these levees are expected to withstand the water to within three feet of the crown of the levee without excessive saturation or change of form. When subjected to water above the three-foot line, they are not considered safe provided there is practically no wave action. The tendency at tne present time is to increase the margin of safety by keeping the water line about five feet below the top of the levee .

One of the most important factors of a levee is its height. The determination of this needs special consideration, since failure is a foregone conclusion if water is allowed to overtop the crest. It is therefore necessary that all levees be built to a height above that of the highest flood level.

The height depends in a measure upon the position of the levee with reierence to the stream, and upon the direction of the current. For example, an embankment so placed that it lies at an angle to the direction of the current will need to be much higher than one parallel to it, for with tne former the water tends to bank up against the levee, while with the latter such is not the case.

Another important matter which must be given consideration in the construction of a levee is the foundation. This is a case, not of selection, but of dealing with the material at hand. In all cases the ground on which the levee is to be constructed must be cleared of all material which will decay. The ground must then be plowed so that the material for the levee will unite with the foundation leaving no cleavage plane. 'then a levee is to be built to a height of more tnan ten feet an exploration trench is usually required. An exploration trench is a ditch about four feet wide and five feet deep, for the purpose of discovering any buried logs, animal dens, or any cause for forming of a passageway through which t.ie water may pass under

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the levee.

The barrow-pit, or pit from which the material for the

levee is taken, should be on the outside of the levee, and or-

dinarily not nearer than twenty feet to it. No material should be taken from the inside. A barrow-pit on the inside of the

levee has the same effect as increasing the height of the levee

equal to the depth of the pit. When, a levee is placed near the bank of a stream, the barrow-pit should not be made continuous; but transverse bars should be left across it, so that the stream will not form a new channel along the base of the levee.

The material of which a levee is constructed is usually that nearest at hand, but some materials are better adapted to such use than others.

VII. DESIGN OF DITCHES.

Obviously, in designing any system of drainage ditches, it is desirable to utilize the present channels as far as practicable, since such a course cuts up the land the least and reduces the cost of construction. This will usually necessitate the deepening of these streams in places, and sometimes thruout their entire length. In the natural channels of most small streams there are usually so many small curves that it is necessary to cut short ditches across bends, thus straightening the channels. By thus straightening and deepening the channels, streams that formerly overflowed their banks during the spring floods are made of adequate size to carry the water. In designing the drainage system for most districts many new ditches are included in the scheme in addition to the natural channels.

When new ditches are constructed they arc located as i'ar as possible on section lines or property lines, so that the farms will not be divided.

Theoretically, the slope and cross-section of a ditch depends entirely upon the area drained, the rainfall, and the runoff; but an engineer who has had wide experience in drainage work has learned that there are several minor factors that must be taken into account, and hence he is frequently required to modify theoretical results in accord with experience. In opening a new country it is necessary for the engineer to study rainfall; but even then, experience on other projects will play a large part in the design of the ditches. In the Mississippi .valley in designing ditches it is considered sufficient to provide a channel for about one half to three fourth inches of rainfall over the entire area drained, while in determining the pumping capacity only one fourth to three eights ol' an inch is used.

After having determined the amount of run-off to be provided for and also the area drained by each ditch, the next point to consider is the slope of the ditch. The slope of the ditch depends to a great extent on the slope of the land, but the former slope must not be so great that excessive erosion will occur, nor so small that the water is not carried off in a reasonable time. A great many formulae have been developed for determining the cross-section of a ditch, but the one in most common use is the Chezy formula, together with Rutter's formula for the determination of the constant "c".

Chezy formula: v=c rs , where

c = a variable coefficient.

r = hydraulic radius = a/p = area divided by wetted perimeter.

s = slope = h/1 = I'all of water surl’ace per unit of length.

Kutter ' s

formula :

c-

/r s

where "n" is the coei'l'icient of roughness. ho little uncertainty attends the determination of the value of "n" , but after careful measurements made under the direction of the United States Reclamation Service, the following approximate values were given for channels described.

0.020

Channels of fine gravel; canals in earth in good condition, lined with well packed gravel, partly covered with sediment and free from vegetation.

0.0225

Channels in earth in fair condition, lined with sediment having occasional patches of algae, or loose gravel without vegetation.

0.025

Canals and rivers of fairly uniform cross-section and slope in average condition.

0.030

Canals and rivers in poor condition with bed and banks partially covered with debris.

Canals and rivers in bad condition, channel strewn with stones, and about one third filled with vegetation.

0.040

Canals half-full of vegetation and having rough banks. The value of "n" used for most ditches is 0.025.

A more simple formula devised by Mr. C. G. Elliott is

sometimes used, and is said to be nearly as accurate as butter's formula. Elliott's formula is:

Q = a v.

v = mean velocity in feet per second, a = area of water way in square feet.

P = wetted perimeter = length of bounding line of cross-section of that part of the channel which is under water, h = fall in feet per mile.

Q = discharge in cubic feet per1 second.

A = number of acres.

R = run-off per acre.

The number of acres which can be drained = A = Q/R.

The side slopes of ditches are usually specified one vertical to one horizontal, tut sometimes these dimensions are varied. The width of the bottom of the ditch depends largely on the type of machine used in excavation. About the narrowest ditch that can be economically dug with a dipper-dredge of the floating type is ten feet, while some types of dry-land dredges will dig a ditch as narrow as can be used. The drag-line machine, another type of dry land excavator much used in ditch work, will dig to a width of about four feet.

VIII. DESIGN OF PUMP PLANT.

One of the most important problems which the drainage engineer must meet, is the design of the pumping plant. The plant should be designed with a view to certainty of operation at any time, to economy of operation, and to cost of maintenance. The first matter to be considered is the choice of the type of prime mover and pump which should be used. The conditions which govern their selection vary considerably in different localities, chiefly on account of the difference in head, the relative accessibility of the plants, the cost of fuel, etc.

In selecting the type of prime mover, consideration should be given to internal combustion engines, electrical motors, and steam engines, all of which have teen used in this class of work. Prime movers of the internal combustion type have some strong arguments in their favor; but before deciding on an installation of this kind, the availability of proper operatives must be given careful consideration. Electric motors are suitable for small plants located near an available supply of current; and the convenience of operation will often offset the increased cost of power. Properly designed steam-driven plants have very good fuel economy, and can readily be run at the various speeds necessary to economical operation under different heads.

Several types of pumps have been used for this class of work, including the propeller-lift pump, the paddle or scoopwheel pump, and the low-head centrifugal pump. The propeller lift pump and the paddle-wheel pump, as constructed in this country, are not durable types of construction. Scoop wheels of a durable type of construction have been used very extensively in England and Holland. These plants operate quite economically at low pumping heads; but are very expensive to install properly, and have not been developed for the extreme ranges of head encountered on the Upper Mississippi.

Taking all these facts into consideration, the type of prime mover and pump which at this time appears to be best adapted to the average conditions are, for large installations, the steam engine and low-head centrifugal pump; and for the smaller installation, internal combustion engines or electric motors.

The Louisa-Des Moines pumping plant differs in only a few details from most other pumping plants on th Upper Misslssippi river; and therefore nothing more need be said concerning its design. The plant is steam driven, and its principal equipment consists of one 300 horse-power Erie-Ci ty-I ron-Works horizontal boiler, equipped with an open-feed water heater, induced draft apparatus, and heater and feed pumps. In addition to the regular boiler gages a recording pressure gage is mounted in the boiler room. There is also a 10 horse-power vertical boiler, which is intended for cleaning the main boiler and starting the auxiliaries. The pump room is equipped with two Erie-City-Iron- Works 250 horse-power horizontal tandem- compound condensing four-valve steam engines, each of which is directly connected to a 50- incn Worthington centrifugal pump. While these pumps are called "50-inch pumps”, they are made from the regular 45-inch pump patterns" with the exception that the discharge opening of the pump volute is expanded to fifty inches. The rated combined capacity of the pumps is £25 cubic feet per second ( 100,000

gallons per minute ) when working against a static head of 12.5 ft. Each of the main engines is fitted with a revolution counter. The pump station is lighted by a small electric plant. The main engine is lubricated by a continuous oiling system. The oil from the bearings is collected and automatically pumped into

a filter located above the engines, from which it is returned by gravity to the engine bearings.

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IX. SPECIFICATIONS.

Since various parts of the work are let to different contractors, the engineer must prepare separate specifications for the open ditches, the levees, the sluice gates, pumps, engines, boilers, pump house, and residence for the stationary engineer. All of the specification issued during the construction of the Louisa-Des Moines Drainage District would be too bulky for inclusion in this thesis, and besides there .would be more or less repitition; and therefore only a sample of the specifications for each type of work have been included. These specifications may be found in the appendix.

X. ESTIMATE OF COST.

The method of estimating the cost of ditches and levee is much the same as that used in railroad earth work; but on account of less precise work being required in construction, the estimates need not be so accurate. Alter the profiles of the ditches have been drawn and the grade lines established, the cuts or fills are measured, recorded and averaged. For convenience in figuring, tables showing the number of cubic yards for a hundred feet of the average cut or fill were compiled and from these the desired volume is read directly. If the cross-section is very irregular, the more accurate method used in railroad work, that of computing yardage from average end areas, is used. Tne price on which these estimates are figured is a matter of experience, and varies according to the number of yards of dirt to be moved, its accessibility, the character of dirt, the price of labor, etc. Ditch work usually varies from eight to ten cents per cubic yard, and levee work from twelve to fifteen cents per

cubic yard.

The estimate of cost of a pumping house is made in the same manner as that of any other building. For data on the cost of machinery the engineer must rely on the manufacturer. In cases where the engineer has had a great deal of experience in pump-plant construction, curves can be drawn from which the cost per horse power for all kinds of plants can be taken directly.

This eliminates the detail work of estimating, and in most cases is accurate as detailed estimates, so, for in detail estimating many items are likely to be overlooked.