p11  Part I
Introduction

New Orleans, April 29, 1895.

Gentlemen:

The Advisory Board on Drainage of the City of New Orleans, appointed by Ordinance No. 8327, C. S., dated November 24th, 1893, have the honor to forward, with its approval, a plan for the drainage of the City of New Orleans. The commencement of the work, as soon as practicable, is recommended.

We desire to recognize the efficient services of Mr. L. W. Brown, City Engineer, and also, of the members of the engineering corps assisting him in the work, both in the field and office.

We further recommend the continuation of the rain-fall record and of the run‑off observations.

Respectfully submitted,

R. M. Walmsley, Chairman,
J. C. Denis,
Albert Baldwin,
B. M. Harrod,
Henry B. Richardson,
Rudolph Hering,

Advisory Board.

Part I
Introduction

Gentlemen:— The undersigned Engineering Committee, appointed by you on December 14th, 1893, have the honor to present the following final report concerning their investigations into the subject of the drainage of the City of New Orleans, as well as their approval of a certain plan therefor, as authorized by Ordinance No. 8327, C. S., adopted November 24th, 1893.

The first steps leading up to this report were taken by the City Council of the City of New Orleans, by the passage of Ordinance No. 7170, C. S., adopted February 6, 1893, an ordinance providing for the making of a topographical survey; and formulating a complete and comprehensive system of drainage for the City of New Orleans, and authorizing the making of the necessary investigations, of which the following is a copy:

When the work was inaugurated, Messrs. Rudolph Hering, B. M. Harrod and H. B. Richardson, were appointed an "Advisory Board of Engineers," under the provisions of Ordinance No. 7350, C. S., adopted March 30th, 1893, which ordinance reads as follows:

Subsequently, the present organization of the Advisory Board was created by Ordinance No. 8327, C. S., which Ordinance reads as follows:

In order to inform themselves of the nature and merits of the various plans that, had been proposed from time to time, relative to the drainage of the city, inquiry was made into the history of the subject; an account of which will be found in Appendix II.

To further learn the views of civil engineers, and others who had plans to present, or were otherwise interested in the subject of draining the city, several public meetings were held, and the information obtained from those gentlemen who appeared before the Board was afterwards carefully considered.

The first of the public meetings of the Advisory Board, after due advertisement, was held in the Council Chamber December 14th, 1893, and was addressed by Mr. S. D. Peters, Mr. Geo. H. Grandjean and Hon. Chas. Louque.

At the adjourned meeting on December 15th, Mr. S. D. Peters appeared, and thoroughly explained his plans.

On February 19th, 1894, the late Mr. J. L. Gubernator appeared before the committee and explained his plan relative to the drainage of the city.

A final public meeting was held, after due advertisement, in the Council Chamber, on February 15th, 1895, and was addressed by Mr. A. F. Wrotnowski, C. E., Mr. G. H. Grandjean, C. E., Mr. A. C. Bell, C. E., Mr. S. D. Peters, and Hon. Charles Louque.

In order to enable your committee to form a safe judgment upon the merits of proposed plans, an inquiry had first to be made regarding all existing information relating to the subject. It was found that some of the essential factors for this judgment were not available. Your committee, at a meeting on May 2d, 1893 (then, acting as a  p14 Board of Advisory Engineers), issued to the City Engineer, Mr. L. W. Brown, the necessary instructions relative to the investigations which were to be made, for the purpose of collecting the data that were absolutely required to properly solve the problem before them. In conformity with these directions, the City Engineer secured the necessary instruments, etc., so that actual work on the topographical survey was begun about the first of July, 1893, after which it proceeded uninterruptedly until about the first of September, 1893, when, by injunction issued by the Civil District Court, the work was stopped. After the removal of the injunction, work was resumed about the middle of December, 1893, and continued until the present time.

With the light thus furnished, your committee thoroughly and carefully examined into the plans submitted at the public meetings, and those which were otherwise available. They found that, while the authors had shown much industry in formulating their plans, they were not based on reliable topographical and hydrographical data, and while they contained some useful suggestions, no one of them would be recommended as a whole by your committee. None of the plans provided with sufficient definiteness for a suitable and permanent improvement of the existing conditions of drainage in the commercial and resident portion of the city, which was deemed by your committee to be a most important part of a drainage plan. It, therefore, devolved upon the City Engineer, Mr. L. W. Brown, to make, with the funds available for the purpose, all necessary computations and plans, and to base them upon the results obtained by the preliminary work that had been done by him, as well as upon all the other information furnished by previous plans and suggestions which were at his disposal. Step by step this work was carefully examined and approved by your committee, which had made itself thoroughly familiar with the territory, its needs, and the propositions for its improvement, and now approves the work as a whole.

In the following, this plan is described in its general features, and a suggestion submitted for the manner of prosecuting the work, and a statement of its approximate cost. In order to justify a recommendation of the plan, it is desirable to precede the description by a statement of the general requirements thereof, to satisfy all the important demands and to solve the drainage problem, not only for the present but also for the future, and by a statement of the essential factors that are necessary for such a solution.

Part II
Statement of General Requirements

An investigation into the principal features and outlines of a drainage system for the City of New Orleans will be made with a view of realizing the inevitable growth and development of the city, and the increasing demands which, at the present time, sanitation, comfort and economy make upon every large modern community.

In the past it was deemed sufficient to adopt makeshifts, one after another, to accomplish some immediate ends and to benefit small disconnected sections. The result has naturally been: a somewhat incoherent and crude system of drains and canals, insufficient in size, depth and slope; a disposal of the water which, regarding its main channels and outfalls, is becoming more and more objectionable; and methods of pumping which are both inefficient and uneconomical.

It has now become clear not only that the city will steadily advance in size and importance, but that means will become available, in proportion to its growth, to better the streets, the railway service, the lighting and water supply, the pavements, the sewerage and also the drainage. Any material improvements of the city that are now instituted, should no longer be temporary expedients, but based upon well digested plans designed to provide for all future contingencies, so far as these can be safely estimated.

The recent establishment of a sewerage system, which is to remove from the buildings to a proper outfall, all foul waste matters that can be carried away in suspension by flowing water, has in some degree affected the drainage question by removing from consideration an element that would have caused a material modification of the problem.

The drainage question of this city to‑day, therefore applies principally to the removal of the rain water falling upon the inhabited and built-up part of the city, which does not penetrate the ground, but runs off into the gutters, and then floods the streets and finally the low territory, causing more or less damage to property and interfering with travel and the transaction of business. It applies likewise to the removal of the ground water which at present saturates the soil, causing unsanitary conditions, besides preventing the usefulness of the territory, for one or another purpose as may be required in a large city.

Many blocks in the city which are not now built up because they are practically swamps, although within convenient distance of the business center, within likewise be benefited by efficient drainage.

A drainage project should therefore be extended to all territory which is now, or will be, built up in a reasonable time, and it should see the removal of rain and ground water from the same, so that the whole area can be made and kept thoroughly dry. This area has been limited for the present purpose as follows, viz.: On the left bank of the Mississippi River, of the territory embraced by the Upper Protection Levee, Lake Pontchartrain, People's Avenue Canal, Florida Avenue and the lower limits of the city; and on the right bank of the Mississippi  p16 River, the line between the parishes of Orleans and Jefferson, the lower side of the naval reservation and rear protection levee, all as shown on Plate IV.

The lowness of the land requires all of the rain and ground water to be lifted by pumps, before it can be actually disposed of. As the area is one of great magnitude, the required pumping capacity will be considerable, and it becomes necessary to adopt such methods of collecting and conveying the water, as will enable the most economical pumps and arrangements to be used. It also becomes a matter of moment to ascertain the most economical lines, sizes, depths and slopes of the canals to facilitate such removal in the most efficient way.

A further important requirement of a drainage plan is the final proper disposition of the water. Since, in the near future, most of the sewage will be separated from the drainage water, it is to be assumed that the latter will soon be much improved in quality, although still containing street washings and leachings from the soil. The storm water from heavy showers is less objectionable in quality. The high dilution of the organic matter will render it inoffensive and harmless, notwithstanding the water may be more turbid from a larger amount of suspended earthy matter that is contained in it.

The question of disposal must be answered in the light of these two conditions of the water. Its ordinary flow should not be delivered where even its slight pollution would be undesirable or detrimental to the value of adjoining lands. It would if possible be discharged at points where no considerable development is expected.

The first flow from a storm generally carries with it the washings from the streets and houses, and is also to a certain degree polluted. It is therefore advisable to treat it like the ordinary flow. The water from heavy rain-falls, however, so largely dilutes the waters just mentioned, that it can be considered quite unobjectionable, at least from a sanitary point of view, and discharged at the nearest available points into any natural water course or lake. As it may sometimes gather up and carry along considerable quantities of silt, due to its greater velocity, care must be taken that no detriment to the canals results therefrom.

The final requirement is the maintenance of the two existing navigation canals to best subserve the demands of commerce. It has been suggested, and with some good reason, that the river end of these canals as far as Broad street might be abandoned for navigation and made available for drainage, but on the lake side of Broad street they should be preserved and kept free from surface water, on account of resulting deposits.

Any plan satisfying all of the above-mentioned demands many necessarily be comprehensive; it must cover a large and now mostly uninhabited territory, and a long time will be required to execute the same. As some of the demands are now urgent, and should be satisfied as soon as practicable, the plan should therefore allow of the possibility of at once carrying out some portions independently of others, so that it will solve the present difficulties efficiently and economically, and at the same time be in harmony with the whole work and facilitate eventual extension and completion.

Part III
Essential Factors for Solving the Problem

The requirements of a drainage system as above noted, necessitate a thorough examination into all subjects, which materially affect the nature of the design. Without a fair knowledge of the essential factors which governor the same, it is impracticable to foresee just what effects would be obtained by a certain design, and therefore, to know whether or not it will answer the purpose.

First of all, it was necessary to have a topographical survey of the territory, indicating the existing and projected streets in their true position, and the character of the surface as to permeability, requiring a record of the extent of area paved and covered with buildings, or of partially built‑up, and of rural and swamp area; and further, a hypsometric survey of the entire area, indicating the height of every part of the surface by horizontal contour lines drawn at every foot of elevation above Cairo datum.

The information available when the committee entered upon its duties, was to a large extent meagre, crude, and unreliable. It was deemed unsafe to base upon it the design of so important a project as the one under consideration. Therefore as a necessary preliminary step, a complete survey was recommended. The results are now available in the shape of numerous maps, indicating the surface characteristics, and of numerous profiles, indicating the sections of streets, canals, etc. Independently of the use to which these surveys are put in considering the drainage problem, they will be use also for the solution of other municipal problems, and are therefore of permanent value to the city. For a detailed description of the topographical and hypsometric work, and for a list of the plans, etc., see Appendix III.

It need here only be stated in general terms that the territory to be drained is highest along the banks of the Mississippi River, where the elevation of the ground is on the average about 33 C. D., the ground sloping from the river towards the la for a distance of about 6,000 to 9,000 feet from the river bank, where the average elevation of the ground is 20 C. D. The surface of ground from the foot of the slope to Lake Pontchartrain is practically flat, with the exception of a slight rise called Metairie and Gentilly Ridges, running substantially parallel with the shore of the lake and about 2¼ miles distant therefrom. The average elevation between these ridges and the lake is 22 C. D. A large portion of the basin between the foot of the slope and Metairie and Gentilly Ridges is below mean gulf level. The elevations of the territory which it is proposed to drain are more fully shown on Plate II. Under existing conditions the major portion of the territory between the ridges and the lake, as also a large portion of the basin between the river and the ridges, is swampy and practically waste land, affording very unsanitary conditions, and providing in its present condition no inducement for general improvement.

The improved portion of the City of New Orleans is situated on the most elevated part of the territory.

 p18  The New Orleans Navigation Canal, and the Carondelet Navigation Canal and Bayou St. John, extend from the lake to Rampart street, at about 4,000 feet from the Mississippi River. These canals are used for navigation purposes, admitting of commerce reaching the city from Lake Pontchartrain, and are leveed on either side to prevent the water from Lake Pontchartrain inundating the low portions of the city.

The present system of drainage does not extend to the lake side of the Metairie and Gentilly Ridges, and there are large areas between the river and these ridges which are not now drained. The present works consist of deep gutters on both sides of every street leading from the river to the foot of the slope, where they are intercepted by open canals leading to the draining machines. These are four in number, and arranged to deliver from an average elevation of 15 C. D., and discharge into Lake Pontchartrain. The system is, from every point of view, wholly inadequate, and the present conditions are further objectionable for the reason that all the foul and other waste waters from the improved portion of the city naturally flow down the slope from the river bank, through the numerous street gutters to the low ground in the rear, and thence to the draining machines, through artificial canals which have not the slope necessary to convey these waters with sufficient velocity, to prevent fouling of the canals, and the formation of obnoxious gases. As the foul waters accumulate in the canals, the several draining machines discharge the same into Lake Pontchartrain, where objectionable conditions are created by the pollution of the water of the lake. For a more delayed description of the present drainage system see Appendix II, and for the area drained, as also the location of the machines, see Plate III.

Another essential factor required, is a knowledge of the quantity of rain water that falls upon the territory to be drained during the heavy storms occurring several times every year. Heretofore, the available records stated only the total amount of water that had fallen within twenty-four hours, or occasionally in shorter times, and only at one point within the city limits.

In order to have an intelligent opinion regarding the true nature and character of the storms, it was necessary for the present purpose to have a continuous record thereof, by which the rate of precipitation at every instant, and the duration of the heaviest downpours is recorded. It was further necessary to know approximately the extent of the area over which a storm of great intensity usually prevails. Six self-registering rain-gauges were therefore placed at different points, as indicated on Plate III. On April 1st, 1894, these gauges were in working order and have since then furnished very satisfactory results. A few of the records of the principal storms, and the deductions therefrom, as well as a description of the method of recording the rain-fall are given in Appendix IV. In the same appendix is also found a table giving a list of rain-falls which exceeded a rate of two inches per hour in the States of Louisiana and Mississippi since the year 1872. Further, a table is inserted giving the heaviest daily rain-falls recorded in New Orleans by the United States Department of Agriculture, Weather Bureau.

 p19  The record of the storm of August 13th, 1894, illustrates the advantage of having a number of gauging stations. The precipitation was more intense during this storm than in any other which occurred during the time these investigations were being made. The total precipitation at the Park station was 2.08 inches, at the Dublin station 2.88 inches, at the Hall station 2.96 inches, at the Jackson station 3.55 inches, at the London station 3.60 inches, and at the West station 2.76 inches. The storm struck the city from the east and traveled westerly. The Jackson and London stations are the most easterly and the Park and Dublin stations the most westerly, showing that the storm decreased in intensity as it traveled.

The records of July 4th, 1894, further illustrate the varying intensity of a storm. On this date there fell at the Park station 2.84 inches, at the Hall station 1.02 inches, at the Jackson station 1.19 inches, at the Dublin station 1.08 inches, at the West station 0.20 inches, and at the London station 0.46 inches. All the records of these instruments have been carefully plotted and the volume of water falling upon different areas calculated and tabulated in Appendix IV.

Although the rain-fall observations have so far given excellent results, and perhaps sufficient to form safe general deductions therefrom, it is yet urgently recommended that they be continued for several years. The results cannot fail to more than warrant their cost when designing the details of the drainage plan in the future.

A third essential factor required to form a judgment upon the efficiency of any design, is the amount of water and the greatest rate at which it flows off the surface and enters the drains and canals during heavy rain-falls; in other words, the actual greatest "run‑off." No system of canals and drains for this city can be proportioned to do satisfactory work, to prevent overflow, or to thoroughly drain the subsoil, without a much greater knowledge of the subject than has heretofore been applied to the purpose. This information was formerly sought to be obtained by an estimate of the water lifted by the draining machines; but the record does not furnish the element of time; it does not state whether or not the "run‑off" was uniform or whether it was great at one time and small at another, the capacity of the draining machines being insufficient to remove the water as fast as it comes and prevent the flooding of extensive areas.

Another way of estimating the "run‑off" was to use old formulae, mainly in the shape of a given fraction of the hourly or daily rain-fall. The assumptions were furthermore taken from European practice, where the rain-fall differs materially in intensity and magnitude from that of the lower Mississippi Valley.

The want of reliable information on this subject compelled your own Committee to obtain it as accurately as was practicable in the short time at its disposal. Actual gaugings were made of the water discharged daily at the several draining machines. With a satisfactory record of a given rain-fall, as mentioned above, it then became practicable to throw some light on the proportion of water that runs off, the remainder being evaporated or held back on the surface or in the ground. It also became practicable to estimate from these gaugings the  p20 ordinary flow during dry weather; a necessary knowledge to proportion the cross sections of the drains and canals, as well as the pumps to do the most efficient work at ordinary times.

There is no opportunity in the city to gauge the immediate "run‑off" from large areas, because the rain water is now held back, to a large extent, in gutters and street depressions. This fact prevents it from flowing off as rapidly as will be the case after the city has been supplied with modern pavements and other improvements which are indispensable to a modern large city.

There was at least one opportunity, however, to get approximately correct information on this subject for certain conditions, and it was an important guide for your committee in their final conclusions. This was in the area drained by the Melpomene Canal. Careful gaugings of the flow in this canal have been obtained during almost every heavy rain-fall which occurred within the past year. These gaugings, together with a knowledge of the extent and intensity of the rain-fall, and of the character of the surface, its impermeability and slope, have given a valuable factor in estimating the run‑off, notwithstanding that much of the water is still held back in gutters and upon the streets before it enters the canal. Aided by information obtained elsewhere it was practicable for your committee to estimate with a reasonable degree of accuracy, the effect of this retention on the basis of the physical character of the surface in New Orleans.

It is evident that the amount of "run‑off" holds a fixed relation to various factors. It will be greater as the rain-fall intensity increases. It will be greater as the imperviousness of the surface increases, or as the territory becomes paved, and covered with buildings; in other words, we might say that it increases in a certain ratio with the density of population. The "run‑off" increases, finally, with the slope of the territory. The steeper the slope, the quicker the water will reach a given point. The water from a distant area on a steep slope is therefore likely to meet the "run‑off" from a nearer one on a flatter slope and causes the respective quantities to combine.

To get information covering the effect of these factors, all the available experience in different parts of the country was consulted and compiled. The actual gaugings made in the Melpomene Canal were given their true value, and from the total results, interpreted to the best of our ability at the present time, several diagrams were prepared. Plate VIII shows the greatest probable rate of "run‑off" in cubic feet per second from areas extending up to •1200 acres and with slopes of the territory ranging up to three feet per thousand, about the steepest existing slope in New Orleans. A set of these curves is given for four different characters of surface; the set marked A represents the "run‑off" from densely built up parts; the set marked B applies to  p21 the area having small yards, or a medium density of population; the set marked C applies to the sparsely built up parts, or those having large yards; and the set marked D applies to the rural areas. These curves, therefore, indicate the maximum rate of rain-fall which it is proposed to provide for, and which is assumed to reach the drains and canals from the respective areas.

They do not warrant the assumption, however, that the discharge will never exceed the quantities given for it; in fact, it is certain that they will be exceeded, but at such rare and indefinite intervals that their consideration is not justified. It should also be remarked that the curves are based upon the assumption, that the present practice of storing the water upon the street surface will be discontinued, and that the water enters the drains promptly, as is the case in most other cities.

In proportioning the size of the canals, it is necessary to provide for future conditions, and an estimate was therefore made as to the probable future growth of the city. Little or no change is expected in the densely populated areas, nor upon others which can only be sparsely settled for some years. On the average it was not found to be judicious to assume an increase in the quantity of water running off, of more than fifteen to twenty per cent. in excess of that which would run off at present were the street storage abolished.

It is required, further, to know the quantity of ground water which will drain from the territory at ordinary times. It consists of the natural seepage from the ground, or in other words, of the water percolating into the drains and canals, and also of those waste waters from buildings, not removed by sewers. Until these sewers are extended over all of the inhabited territory, sewage will still mingle with that ordinary drainage flow, but it will decrease in proportion to their extension.

The seepage itself, when coming from the built‑up territory, will, however, always remain slightly polluted. It will not be as offensive as it is now, but it is nevertheless wise to provide against its becoming objectionable. For this purpose it should be removed in properly lined canals, and not in earth ditches, where any suspended matter may be deposited and where stagnation may take place. By flowing over a smooth, hard surface, and also at a velocity of several feet per second, these objectionable results will be prevented. None are found to exist where similar canals with masonry channels carry away the ordinary drainage flow from a city. This subject will be further alluded to in describing the proposed sections of the canals.

In order to ascertain the quantity of water to be provided for at ordinary times, we should recognize first, that it will be reduced to below the present quantity by two causes. One, is the removal of sewage from the drains and its disposal into the Mississippi River, the other, is the gradual decrease of rain-fall penetration into the ground by a greater building up and paving of the city. On the other hand, the quantity will in the future tend to be increased, by the fact that the drains and canals will be deeper than at present, thus furnishing better conditions for infiltration from the river and from the lake. In  p22 view of these opposing tendencies it has been concluded that a provision for the ordinary flow in the future should be based upon the present quantities, as deduced from the records obtained at the several draining machines, and as given in Appendix V. They have been adjusted to the proposed new drainage sections of the city, and represent the amounts probably to be lifted at the proposed pumping stations. The resulting effect of the proposed manner of removing the ordinary flow of water, will be to materially lower the water level over all parts of the territory under consideration, including the swamp areas, and to keep the entire territory permanently dry and available for improvement.

In the opinion of your committee, the principal reason why so many projects for the solution of the drainage problem have been proposed, and again abandoned, is the fact, that insufficient information was at hand to definitely, and positively, determine its hydraulic features, and that there could be no assurance regarding the exact effects, or the results, that would ensue upon the carrying out of any of the numerous propositions.

Part IV
Project Recommended

A. Outfalls

The first and most important part of the problem to be determined is the final disposition of the drainage water, or in other words, the outfalls. Having fixed these points, the lines of the canals collecting and delivering the water, can then be suitably arranged.

There are, in the main, three localities where it can be disposed of, namely: the Mississippi River, Lake Pontchartrain and Lake Borgne. It will not require more than the mere statement, that the river should not be the receptacle of the drainage water. The ground slopes naturally from the river levees back to the swamps and the lakes. The surface water therefore flows away from the river. To reverse its flow would require deep and large canals through the city to the river. As the latter is usually higher than the surface of the largest part of territory to be drained, all the water would have to be pumped, and during freshets the lift would be considerable.

Economical drainage outfalls are to be sought either in Lake Pontchartrain or in Lake Borgne; at present the former is used for this purpose.

It was above stated that the ordinary drainage flow and the water from slight rain storms, although considerably improved after most of the sewage has been separated therefrom, will still be somewhat polluted, and its outfall should therefore be selected so that no objectionable consequences can arise. It was also stated, that the water from heavy rainfalls will so dilute any objectionable matter that its disposal can be accomplished without reference to any but economical requirements.

The advantages of and objections to Lake Pontchartrain receiving the drainage are as follows:

It is nearer to the center of the city than Lake Borgne and the canals discharging the water will therefore be shorter and less expensive. It is at present used for an outfall, and several canals already lead to it from the city, making a continuance of this method of disposal less expensive than a different method. On the other hand, numerous pleasure resorts are located along the shore. It is therefore desirable to protect the lake water even from slight pollution. The lake is land-locked, which prevents a rapid tidal flow in and out, or any material circulation of its water. Under these circumstances, as is the case at present, a pollution becomes a serious matter. A discharge into the lake of the ordinary flow and of that from light storms should therefore be avoided. The water from heavy storms on the other hand can be discharged into it without detriment.

 p24  The advantages of and objections to Lake Borgne as a receptacle for the drainage are as follows:

The borders are mostly uninhabited and a slight pollution of the water has no disadvantages. It is open to the Gulf, and the tides rise and fall more rapidly. The greater fluctuations cause a more complete dispersion and a more rapid removal of the drainage water. The mean level is several inches lower than Lake Pontchartrain. The distance from the city to the lake is somewhat greater, but Bayou Bienvenu, which by dredging can readily be made of sufficient size to convey the drainage water, runs from the lake nearly to the levees of the city and can be utilized, without detriment, to receive the drainage flow. It is, also, the natural outfall for the drainage of a large part of the city.

In our opinion, the proper place therefore to discharge the daily drainage from the City of New Orleans, and the more or less polluted water from light storms, is Lake Borgne. Although farther from the city, it possesses, as indicated, a number of material advantages over Lake Pontchartrain as a drainage receptacle, which make it decidedly preferable.

The amount of rain water which must be discharged after heavy storms is, however, so great, that it becomes impracticable to carry all of it to Lake Borgne. But as the water is then less objectionable in quality, it can be delivered with impunity at the shores of Lake Pontchartrain. Therefore, only the water from light rains and the daily flow should be taken in a canal to Lake Borgne, and relief canals at suitable points along the route should take the excessive quantities to nearer outfalls situated along the shores of Lake Pontchartrain. A discharge into the latter will then take place only occasionally, and after the first wash of heavy storms has been directed towards Lake Borgne. The character of the drainage water delivered into Bayou Bienvenu and the Lake, will by no means be sewage, nor resemble the water now observed in the drainage canals of the city, as the proposed sewerage system has a capacity sufficient to prevent the foul water of the built‑up parts of the city from reaching the drains, and for delivering all of it into the Mississippi River. B. General Features

The various plans and suggestions for carrying the drainage to the outfall, which have been before the committee, were carefully compared as to efficiency and cost of construction, pumping, and general maintenance, with the result that the following general features of a plan are recommended as accomplishing the most efficient and comparatively least expensive drainage of the city, both ultimately and for the present.

In the statement of the general requirements for a drainage system, the territorial limits were designated for which it should provide improved drainage, that is adapted to present as well as future conditions, when the population has materially increased, buildings are more densely crowded and the paving of streets is more extended and impervious. The territory embraced within these limits has been divided into drainage sections as follows:

The First Section includes the area between the river and the lake, and between the upper limit of the city and a line extending along the New Canal and thence by Howard avenue, Camp street, Poeyfarre street, Magazine street and midway between Gaiennie and Calliope, between Fulton and S. Peters, and between Thalia and Melpomene streets, to the river. This section contains 8,887 acres.

The Second Section includes the territory between the First Section and the Bayou St. John, Carondelet Navigation Canal and Toulouse street. Its area is 5,384 acres, of which 1,293 are between Broad street and the river, and 4,091 between Broad street and the lake.

The Third Section lies between the lower limit of the Second Section and the line of People's avenue, Gentilly Ridge, London avenue, Broad street, St. Bernard avenue, Claiborne avenue and Elysian Fields. It includes 1,118 acres between Broad and Hope streets, Florida avenue and the river, and 3,564 acres between Broad and Hope streets, Florida avenue and the lake.

The Fourth Section comprises the territory between the lower limit of the Third Section and Gentilly Ridge, People's avenue, Florida avenue and Independence street. Its entire area, 2,153 åcres, is between Gentilly Ridge and the river.

The Fifth Section embraces the territory between the lower line of the Fourth Section and the lower line of the city, and contains 2,878 acres.

The territory on the right bank, designated as Algiers Section, comprises the territory between the upper parish line, lower limit of U. S. Reservation, Mississippi river and rear protection levee, containing 948 acres, and is treated as a separate section.

The boundaries and areas of these sections are shown on Plate IV.

 p26  The reasons hereinbefore presented have led to the conclusion that it is desirable to deliver the greatest practicable volume of drainage water from the entire city through a canal connecting with the headwaters of Bayou Bienvenu and thence into Lake Borgne. Therefore, a main canal leading through the area to be drained, and to which the branch canals and drains of the several sections described are tributary, is made a fundamental feature of the plan.

The location of this "main canal" is shown on Plate IV. It extends from the intersection of Nashville avenue and Claiborne street in a direct line to the present head of Broad street at Napoleon avenue, and along Broad to Hope street at the intersection of Bruxelles street, and thence along Hope street and into and down Florida avenue. The connecting canal from Florida avenue to Bayou Bienvenu will be dredged, and certain reaches near the head of the Bayou enlarged by dredging, and cleared by the removal of sunken logs.

The contours and profile of Plate II show that the main canal is located in the lowest depression between the river and the Metairie and gentilly Ridges, and therefore, in the drainage of the city, it makes the greatest use of gravity that the topography allows.

The duty which this canal is to perform is the removal, not only of the daily flow during periods when there is little or no rainfall, but all run‑offs from storms in the several sections, which do not exceed, in any part of its length, its ultimate discharging capacity. It also serves as a basin for the collection of storm-water (to the extent of its cubic contents), during the time necessary to get the pumps started.

It is provisionally designed with a main (or high-water) channel, and a sub (or low-water) channel. The width of the high-water channel is about 70 feet, and the maximum depth at or about 5 Cairo datum, or 15 feet below the mean natural surface (20 C. D.) on the line of its location. These dimensions have been limited by considerations of convenience and safety in construction and with a view to a discharge of 3,000 cubic feet per second.

It is proposed to line the entire bed and sides with smooth and permanent material in order to insure cleanliness, and a good velocity and discharge. When crossing the navigation canals, special study will be required as to the best detailed method of so doing. But in no case will there be any practical difficulties. The water will probably be best carried across and under the same by large iron pipes, in such a manner as to avoid a depression or siphonic action, and any trouble in maintenance.

As this main canal, in its entire length and dimensions, will only be required when, to the run‑off from the city in its present condition, is added that which is estimated for the improvements and extensions of the next 50 years, and as it is not included among the earlier parts of the construction which are recommended further on in this report, for the purposes of affording immediate relief, it is wise to leave the final determination of its exact dimensions to the experience which will be acquired as the work progresses.

 p27  Branch canals start from the main canal, and then diverge with constantly decreasing capacity, separating into main drains, branch drains, and surface gutters, which extend to the limits of each section, however remote, on either side of the main canal. The system is shown on Plate IV, and has, in addition to that furnished by the main canal, a large storage capacity.

The details of the plan include the re‑grading and lining of the street gutters. These will be of shorter length, of smaller size and discharge than at present, and constructed in such a manner as ultimate location and other conditions will determine. When their necessary capacity would become too large, branch drains are substituted, which have smooth and permanent sides and bottoms, and are generally to be covered. Their dimensions should be such as to admit of location under the sidewalks. Their direction and location is controlled by the contours of the ground, so as to give the greatest efficiency in collecting the drainage.

The volume of water accumulating in these branch drains is intercepted by main drains, whose general direction is at right angles to the former. This volume requires dimensions, which, in some cases, admit of a location under the sidewalk, but in others require it to be under the road‑way. In both cases, they are covered and provided with man‑holes for inspection, cleaning and repair. These main drains in turn discharge into branch canals, which lead directly into the main canal. Their construction is similar to that of the main and branch drains, but they have greater dimensions. These details of location, excepting for the surface gutters are plainly shown on Plate IV. A list of the branch canals in each section and a tabulation of their discharges is given below, while the same information concerning all the other lines of drainage is given in more detail in Table XI.

The drainage of the First Section is collected into eight Branch Canals, which are tributary to that part of the Main Canal located immediately above the New Orleans Navigation Canal and Pumping Station No. 1. Of these Branch Canals, six on the reply-side are located respectively on Claiborne, Nashville and Napoleon avenues and on Toledano, Melpomene and Venus streets; and two, on the lake-side, on Claiborne avenue and Venus street. The last mentioned is in its functions at different times either Branch or Relief canal, as explained below.

The drainage of the Second Section is collected into two Branch Canals, tributary to the main canal between the two Navigation Canals, which is served by Pumping Station No. 2, located immediately above the Carondelet Navigation Canal. Of these two branches, one is on St. Louis street on the river-side of Broad street, while the other, occupying the location of the present Toulouse Canal, drains the area on the lake-side of Broad street, and has the same alternate functions as the Venus street Canal above mentioned.

 p28  The Branch Canal on St. Louis street for the drainage of this section between Broad street and the river, is well located and entirely practicable. Should the city have the opportunity to acquire, for drainage purposes, the use of that part of the Carondelet Navigation Canal, situated between its head at Basin street and the lake side of Broad street, at a reasonable cost and without prejudice to the navigation and commercial interests of the community, it could be used to advantage for these purposes, and in lieu of the St. Louis Canal. The construction would be cheaper on the line of the Navigation Canal than on St. Louis street, as a covering to restore the present St. Louis pavement would not be required. A crossing of the Navigation Canal by tunnel or siphon would also be obviated, although this feature does not present any special difficulty or great cost. On the other hand the re-establishment of commercial and navigation facilities by the construction of a basin and wharves at or above Hagan avenue and the building of streets leading thereto will be a necessary part of this alternative, and it is quite probable that the cost of these, together with that of acquiring the partial use of the Navigation Canal, and the opposition with which this, as a new proposition, might be met, would nullify any advantages the suggestion possesses.

The drainage of the Third Section is brought through four Branch Canals to the Main Canal. Those on the river-side are, respectively located on Orleans and St. Bernard avenue. Those on the lake-side enter the Main Canal from Orleans street and London avenue, and the latter also serves both as a Branch and Relief canal, as do those in the First and Second Sections already mentioned.

In the Fourth Section there are five Branch Canals tributary to the Main Canal. Three, from the river-side, enter at St. Anthony, Washington and La­fayette streets, while two, from the lake-side enter at Marigny avenue and Washington street.

In the Fifth Section there are four Branch Canals. They are located on Louisa and France streets and Jourdan avenue, while one comes from the lower limits of the section.

In Algiers, there will be a pumping station on Lawrence street discharging the drainage of this section into an outfall canal, leading into Bayou Barataria.

The principal Canals leading thereto are on Lapeyrouse street, Vallette street and Canal avenue.

The proposed plan thus provides for the thorough drainage of every part of the city, within the boundaries described, which other plans do not.

It is less expensive than any of the others before us, if they were all made equally efficient and built in the same substantial manner as proposed further on. It is also less expensive in maintenance than any of the others including pumping and keeping the channels clean, if they are to accomplish the same results in drying the wet grounds and in removing the storm-water; and if the channels are equally well built.

Also, it is superior in its sanitary effects on account of the removal of the ordinary polluted drainage to Lake Borgne and the improvement of the condition of the shores of Lake Pontchartrain; also on account of the better velocities throughout the system by which any foulness of undesirable deposits are much reduced. C. Run‑off provided for

The run‑off to be collected into the minor canals and discharged through them into the main canal, is computed from the run‑off curves represented on Plate VIII described above in which due consideration is taken of heavy rain-falls recurring with sufficient frequency, to make their entire and immediate removal necessary, of the surface slope, of the character of the drainage areas, and of the present and prospective density of population.

These curves are based upon the results of the surveys, gaugings and observations made by the City Engineer's Department under the advice of the Advisory Board during the past two years and upon a comparison of these results with those of similar observations in other cities presenting like conditions.

 p30  The amounts in the fourth and fifth columns of the foregoing table, represent the run‑off which may occur from any of the areas of the territory according to their differences in extent, slope and density of population. The discharge given for each branch canal may, at times, reach the main canal; but in any one section, the greatest run‑off from its several sub-divisions will not reach the main canal at the same time. The tributaries are of different lengths. They come from tracts with different surface slopes, extent, shape and character. One section is a narrow strip, from the river to the lake. At one end is the most densely built and completely paved part of the city, with a steep, short and direct run‑off to the main canal, while at the other is the low flat area, thence to the lake, with long leads and light grades.

Another section is roughly semi-circular, with the Branch Canals converging from several directions with approximate regularity, from comparatively uniform slopes, and areas more homogeneous in the character of their settlement than is the case in other sections.

Every section, particularly the second section, comprises extremely varied conditions of urban and suburban drainage.

These different conditions determine the relativeness of discharge from the branches into the Main Canal, and the effect thereof must be considered in estimating the volume to be dealt with at any one time, or at any one pumping station.

While every tributary to the Main Canal, or to any canal immediately above a pumping station may at sometime during a storm run completely full, it is very improbable that all of them will ever run full at the same time.

In each of the sections again, the run‑offs from the several Branch Canals reach the Main Canals at the pumping stations may, therefore, be greater in some instances than the differences of the time of their delivery into the Main Canal.

Finally, for the reasons just applied to the run‑offs within the different sections of the city, and for the entire drainage area of the city at the same time, and with equal intensity and duration, it is still more improbable that the run‑offs of the different sections will all combine so as to pass through any one of the sections of the Main Canal at the same time.

Therefore, it is certain that a reduction can be made from the sum of the volumes given in the preceding table. The conditions are so various, and admit of so many combinations, that this reduction is largely and properly a subject for the judgment and experience of the constructing engineer.

The plan now being described, contemplates the completion of every part and detail, Main and Branch Canals, Drains and Branch Drains, Pumps and Out-fall Canals, with a view of meeting the requirements of the city with the development and extensions that may  p31 occur within not less than fifty years. Even were it financially practicable, it is evidently unnecessary and unwise to do a large part of the desired work for a long time to come.

As the canals and drains are intended to deliver the surface run‑off to the pumping stations, the completed pumping power will not be required until the entire completion of the drains and gutters. Under these conditions, during the time of construction and use of those parts of the plan which it may be decided to put in at present, and from time to time, there will be ample opportunity for the observation and experience required for a revision of the ultimate figures, as herein given, if this should be necessary. This course insures efficiency and economy.

The amounts given in the fourth, fifth and sixth columns of the foregoing Table are, therefore, excessive, for the purpose of estimating the required pumping power. The reductions proposed are stated in detail in a description given below of the different pumping stations.

But with any reduction, which, for these reasons, can be made from the volumes in the table, the remaining amounts are in excess of the discharge which can be obtained by the natural slope of a canal built under the existing topographical conditions. D. Velocities and Cross Sections

The dimensions of a canal or drain are calculated not only from the quantity of water to be removed, but also from the velocity with which the water can flow, for, the smaller this is, the larger must be the cross-section. Velocities are determined by the slope and character of the perimeter of the channel. They are limited in this case by the available slopes and the nature of the channels.

When these are lined with masonry, the velocity can be as great as obtainable by any slope available in New Orleans, perhaps 8 feet per second. When the channels are not lined, they are subject to erosion and the velocity should not be greater than that which prevents a destruction of the bed. In earth channels, though protected somewhat by the growth of vegetation, and considering that the greatest flow and therefore velocity is not continuous, but occurs only after rainstorms, the computations have been based on a maximum velocity of 3½ feet per second. When the slope would cause a greater velocity the channel is assumed to be lined. But in unpopulated districts, where this would be unnecessarily expensive at first, it is desirable to reduce the slope temporarily by increasing the sectional area.

The least velocities of flow in the drains and canals should be greater than those usually assumed for sewers, because heavy materials, such as sand, etc., are carried along in them. The least velocity masonry lined conduits for the removal of storm-water has been assumed at three feet per second, and for the removal of the ordinary flow, to prevent deposits and gradual filling up, at six feet per second.

Pumping this ordinary flow and that of small storms in the Main Canal, will, of course, increase the velocity by increasing the slope, and therefore the discharge.

With the above assumption the slopes of the canals and drains have been obtained, and in view of the large quantities of storm-water to be dealt with, the slopes were made as great as possible.

In the larger canals it is advisable to have special sub-channels of sufficient capacity to convey the ordinary flow. This channel can then be made to deliver its charge with the best velocity and concentration of the volume, instead of spreading out over the wide section necessary for storm-water removal, thus facilitating deposit and causing an unsightly appearance.

For storm-water removal, the sections adapted for the numerous canals and drains are governed by the feasibility of making the excavation, by the necessary highest elevation of the water, and by the required capacity to discharge given amounts of water. As a rule they should be shallow and wide.

The plan proposed, and for which estimates are furnished, includes the lining of the sides and bottoms of most of the canals and drains and the covering of the smaller ones, between Broad Street and the  p33 river and in the built‑up part of the city, in a durable manner and with a smooth interior surface. Eventually, nearly all of the drains and canals will require a similarly permanent lining, but for a long time this necessity will not exist. But whenever they are permanently improved, their section should be made large enough for all time.

Wherever practicable and necessary, the drains and branch canals should be covered, so as to gain the use of the surface of the street, guard against the danger of persons and animals falling into them, and to protect them from an excessive amount of street rubbish being thrown into them.

It has been stated that covered drains and canals would become offensive. But this is not to be expected after the sewerage system has been completed and the greatest portion of foul matter removed from the drainage. In Paris the street water and house sewage, excepting most of the excrementitious matter, are carried off in covered channels with wide and untrapped openings at the gutters to receive the drainage, and without being offensive.

The special manner of covering, as well as the many difficult problems of detail that must be considered in the execution of the proposed drainage plan, in order to achieve success and at the same time be economical, should be left to the constructing engineers. E. Pumping Stations

The surface of the ground along the line of the Main Canal is rally level, ranging from 19.5 to 21.5 C. D. The length of the canal is seven miles, the width is provisionally assumed at about 70 feet, and the depth is limited by the stability of the subsoil, and varies from 14.5 to 16.5 feet below the natural surface. Where it discharges into Lake Borgne, the mean tidal level is 21.26 C. D., but this may be increased three feet or more in great storms.

The Main Canal is to serve two distinct purposes. In the first place, it is intended to remove the ordinary drainage flow to the possessed outfall, in a proper manner. Owing to the great distance, the absence of fall, the fact that such ordinary flow should be given a suitable velocity, and in order to prevent sanitary objections in the future, it is absolutely necessary to lift this ordinary flow at a sufficient number of points so as to give it artificially the slope which cannot be had naturally by the topography. The plan, therefore, includes a series of main pumping stations, five in number along the Main Canal.

Secondly, the Main Canal is to carry away the water from rain-falls to such an extent, that the first wash from the surface of the streets, will as far as practicable be discharged into Bayou Bienvenu and Lake Borgne, rather than in Lake Pontchartrain. It has been considered that a rain-fall giving a run‑off of 3,000 cubic feet per second, at the lower end of the main canal, might be sufficient for the above purpose, and the canal has been provisionally designed for this quantity. For small rain-falls it will seldom be necessary to operate all the pumps, as any flow greater than the ordinary, will require a lighter slope for a given velocity, and the water can flow by gravity past several of the pumping stations without objection. In fact, there will be times after moderate rain-falls, when the water slope in the Main Canal can be made sufficient by the operation of merely the terminal pump at Jourdan Avenue, to finally deliver the run‑off beyond the drainage limits. Therefore, provision must be made at each of the pumping stations on the Main Canal, for allowing, at certain times, an unimpeded flow, and at other times, for holding the artificial head which the pumps will make.

When the capacity of the lower end of the main canal becomes insufficient to carry off the water from a storm, then it is necessary that the pumps deliver the excess into the branch relief canals, to flow to the auxiliary pumping stations, hereinafter described, and thence into Lake Pontchartrain. This surplus water will as a rule, be wholly unobjectionable in its character, and if it is discharged into Lake Pontchartrain will give no offense whatever.

Provision must therefore be made at the pumping stations for these several duties.

The pumps must handle, at certain intervals of distance, the daily flow during periods when there is little or no contribution from rain-fall, so as to give fall and velocity for its discharge into Lake Borgne.  p35 The volume of this dry-weather flow from the several senates, is estimated to be as follows:

These amounts are progressively cumulative, and for their removal the daily operation of the pumps, on the line of the Main Canal, will be necessary. The lift at each pumping station will be from three to four feet, except at Pumping Station No. 5, where it is delivered into the main out‑fall canal. As before described, a sub-channel of the Main Canal, as shown in Plate IX is designed to carry this flow within its banks.

During ordinary storms, the lift for high water pumping will be about the same as that for pumping the low water flow, but the volume will of course be much greater. Further details concerning these lifts and volumes, are given below.

If the diversion of the excess of volume from the Main Canal to Lake Pontchartrain were accomplished solely by the pumping stations along the line of the Main Canal, the distance to the lake with the slope necessary to properly discharge the required volume, would demand a very great lift; and the branch relief canals being in such a case on a high level, would not admit of the easy drainage of the areas situated between the ridge and the lake. These difficulties might be removed by the establishment of additional pumping stations, either on or near the lake shore, which would divide the lift, bring the canal to a low level and admit of the drainage of the adjacent lands. But there are objections to this location of the pumps, as follows:

1st. The daily or dry-weather drainage, seeking this canal, would have to be removed from the lower end into lake Pontchartrain, and require the daily operation of these outlying pumps, as well as of those along the Main Canal, and causing the continuous pollution of the lake which it is desired to prevent in the future.

2d. The bottom of the relief canal, at its lower end, would be at a depth where the stability of the sub-soil is doubtful.

Auxiliary pumping stations centrally located between the ridge and lake could not be subject to such objections and would give more prompt and efficient drainage, and are therefore, recommended.

The plan provides for such locations at Bordeaux street, and Taylor and Monroe avenues, as shown in Plate IV. The lift is moderate and the intermediate reach between the two pumping stations, is lowered to a level which will serve for the rapid and complete drainage of the low tracts between the ridge and the lake.

In dry times, the drainage water of these lands will seek the low level reach of the branch canals, and flow by gravity through a by‑pass, provided at three of the main pumping stations, into the sub-channel of  p36 the Main Canal, for a final disposal into Lake Borgne. During a higher flow in the Main Canal, these low level reaches of the branch canals serve for purposes of temporary storage, until a further rise of the water renders it necessary to start the auxiliary pumps at the other end of the reach. At no time should the water surface be allowed to rise sufficiently to flood the lands along the banks of the low level canal, or arrest its drainage.

Your committee is not prepared, at the present time, to give exact information regarding the capacity which should be given to all of the pumps to be erected at the different stations; because it depends to a large extent on the improvements that are intended to be made in the drainage system within the next few years. However, a general outline of the location and work required of each one, as forming part of the recommended plan, and approximately the volume and lift are given as follows:

The volumes assumed are smaller than those given in the table on page 29, for the reasons hereinbefore stated. Pumping stations numbers 1, 2, 3, 4 and 5, along the line of the Main Canal, are designated "Main Stations;" and numbers 6, 7 and 8, at the ends of the Branch Relief Canals, are designated "Auxiliary Stations."

Main Station No. 1 is located on the line of the Main Canal at Venus street, and disposes of the drainage of the First Section. The aggregate run‑off through the several branch canals of this section, as shown in table on page 29, during the greatest storms provided for, is 5,404 cubic feet per second. As the Branch Canals, tributary to this section of the Main Canal, converge from different directions, mainly from large areas of easy grades, and small density of population; and as they are of considerable length, and together with the Main Canal, afford a large storage capacity, for reasons assigned on page 30, a reduction of one-third may be made from the above amount. The run‑off to be pumped at this station, at any one time, is therefore assumed at 3603 cubic feet per second. But a further deduction of 865 cubic feet per second can be made, because this quantity enters the Branch Relief Canal between Pumping Stations numbers 1 and 6 from the lands of the section in the rear of Metairie Ridge, and will be pumped at the Auxiliary Station No. 6.

The Main Station No. 1, therefore, deals with 2738 cubic feet per second, as follows: 1750 cubic feet are to be lifted from an elevation of 16 to 19 feet above C. D., and delivered into the Main Canal of the Second Section, and 988 cubic feet are to be lifted from an elevation of 16 to 20 feet above C. D., and delivered into the branch relief canal leading to the Auxiliary Station No. 6, at the intersection of Bordeaux and Upperline Canal. At the latter 865 cubic feet will be added, as mentioned above, giving a total volume of 1853 cubic feet per second to be lifted at this Station, in times of extreme rain-falls, from an elevation of 15 to 27 feet above C. D. This latter lift is not only the necessary head to effect a discharge at mean lake level, which is 21.26 feet above C. D., but also during exceptionally great storms, which may raise this level 3 or 4 feet.

 p37  Following the same method of estimating, the present volumes to be provided for by pumps at the other Main Stations are as follows:

Main Station No. 2 on the Main Canal at the intersection of St. Louis street, according to the table on page 29, may receive a run‑of 2589 cubic feet per second from its two tributaries. The amount from the river-side, being 1458 cubic feet, is not materially reduced, but assumed at 1400 cubic feet, while that from the ridge is reduced from 1131 to 700 cubic feet, giving an aggregate of 2100 cubic feet per second. The run‑off from the Second Section to be provided for at Station No. 2 in great storms is therefore 1400 cubic feet per second. To this is added the volume pumped at Main Station No. 1 from the First Section, namely 1750 cubic feet.

Main Station No. 2 therefore deals with 3150 cubic feet per second, as follows: 2250 cubic feet are delivered into the Third Section of the Main Canal, with a lift from elevation 17 to 20 feet above C. D.; 900 cubic feet are delivered into the branch relief canal with a lift from elevation 17 to 19 feet above C. D., and conveyed to the Auxiliary Station No. 7, at the intersection of Taylor Avenue and Orleans Street. Here are added the 700 cubic feet assumed as being tributary to the Branch Relief Canal, giving a total volume of 1600 cubic feet to be lifted from an elevation of 14.08 to 27 feet above C. D., and flow to the lake by gravity.

Main Station No. 3, on the main canal at Help street, according to the table on page 29, receives an aggregate run-off of 1727 cubic feet per second, of which 1150 cubic feet are from the river-side. The latter is assumed at only 1000 cubic feet, to which is added 2250 cubic feet, delivered from the Second Section, making an aggregate to be lifted at Pumping Station No. 3, of 3250 cubic feet per second. Of this quantity 2000 cubic feet are delivered into the Fourth Section, with a lift from elevation 17.4 to 20 feet above C. D., and the balance, 1250 cubic feet, into the Branch Relief Canal, with the same lift. At the Auxiliary Station No. 8, located at the intersection of London and Monroe avenues, this amount together with 300 cubic feet representing the run‑off from the rear lands, or together 1550 cubic feet per second, is lifted from elevation 16.40 to 27 feet above C. D.

Main Station No. 4, at La­fayette avenue and the Main Canal, according to the foregoing table, receives a total run‑off of 1256 cubic feet per second, which could now be reasonably reduced to 1000 cubic feet. This amount is increased by 2000 cubic feet from the Section above, making 3000 cubic feet per second to be disposed of as follows: 2500 cubic feet per second are discharged into the Fifth and last section with a lift from elevation 16.5 to 20 feet above C. D., and 500 cubic feet per second into the Peoples'º Avenue Canal with a lift from elevation 16.5 to 27 feet above C. D., sufficient for the water to flow into the lake by gravity.

Main Station No. 5 at Jourdan avenue receives 2500 cubic feet per second from the Fourth Section, and about 500 cubic feet per second as the reduced run‑off of the Fifth Section. These quantities are delivered with a lift from elevation 16.68 to 28 feet above C. D., into the canal leading to Bayou Bienvenu and thence into Lake Borgne.

 p38  The drainage of Algiers on the right bank of the Mississippi river, as shown on Plate IV, is accomplished by a similar system of Gutters, Branch and Main Drains, and Branch Canals leading into a Main or Intercepting Canal located on Canal avenue. From a main pumping station, located near the intersection of Lawrence street and Canal avenue, the total run‑off of the section, amounting to 671 cubic feet per second, may be reduced to 400 cubic feet per second, and will be lifted from an elevation of 18 to 25 feet above C. D., and delivered into the outfall.

For the purpose of obtaining the fullest advantage of the proposed system it must be kept pumped down, throughout all its branches and mains, to the lowest possible level. Constant vigilance and care must also be exercised to keep both the larger and smaller canals free from deposits of every kind. They will not all be entirely self-cleansing, and neither this nor any other system will be worth building, unless ample provision is made for its care and operation.

In the foregoing is approximately stated: the daily flow, which requires to be lifted, at the various Pumping Stations, in order to keep the territory dry; the run‑off or storm-water flow which will probably have to be lifted and discharged into Bayou Bienvenu, and, during excessive storms, also into Lake Pontchartrain; finally, the capacity of the pumps at the several stations.

This stated capacity will not be at present required, but, as the population increases, and the surface, upon which the rain falls, becomes more impervious, proportionately more water will run‑off into the canals and require pumping. The rate at which this quantity will increase, must be left to future observations, which, from time to time, will determine how soon and to what extent the pumping power of each station should be increased.

As already mentioned, there is a large storage capacity in the canals, which will be utilized until the storm pumps can be put into operation. The problem which will require attention in the future, is not only to find the capacity of the pumps required, to throw out the greatest quantity of water that will enter the main canal in each respective section, after it has filled up and the limit of its storage capacity is reached; but also to pump out the stored quantity itself in that space of time within which it is desired to have the canals resume their ordinary condition of flow. These questions can be readily determined after some portions of the drainage system have been put in operation. It is impracticable to answer them with sufficient accuracy at present, nor is it necessary. In the future, pumps should be added as they are needed, and sufficient land should now be acquired at each station, and the structures be designed to admit of extension.

The present draining machines, though simple in their action and requiring but ordinary intelligence to operate, are nevertheless by no means economical for the purpose of lifting the water. Since they were built, the progress in the design of pumps has been considerable; and advantage should be taken thereof in establishing the Pumping Stations for the proposed work.

Part V
Prosecution of Work; its Proper Order and Extent

Without prejudice to its final completion the plan allows great latitude in the order with which the construction of its several parts may be undertaken in any section. It also permits the execution of effective work to any extent however small or great for which means may be, or may become, available. Almost any one of the numerous canals, branches, drains, pumps, etc., proposed in the plan, may be built with the certainty that its immediate effect will be to relieve, to some extent, certain parts of the city from their present unsatisfactory condition as regards drainage, and that the work done will be of permanent and increasing value, as the extension of the plan proceeds.

But the largest benefits will, in general, closely follow the locality where the works are most nearly complete. Thus, if only the Main Canal, with its Pumping Stations and Relief Branches were put in operation, the drainage of their immediate vicinity would be at once accomplished; though little or no benefit would result to the remoter regions until they were penetrated by the Branch Canals and Drains, designed to carry off their drainage, and these conduits were, in turn, connected with an improved system of street grades and gutters.

On the other hand it is evident that while the grades and gutters of the streets in any portion of the city may be so improved as to greatly facilitate drainage, such improvement can only effect a local benefit, the Main Drains, Canals and Pumps being necessary for the final disposal of the run‑off. Both parts of the plan, the pumps and main canals, as well as the minor channels and improved street grades and gutters, are essential for the efficient drainage of any of the sections. Nevertheless, the several sections may be separately treated, in case considerations of finance or policy, or other reasons, are found to make such a course desirable. But no part of the improvement should be undertaken which in its effect, increases the quantity of water collected at any point, without providing for the necessary pumps and canals to properly dispose of it.

As it is proposed to discharge the excessive volumes of storm-water, brought to the Main Canal from the upper sections of the city, into Lake Pontchartrain by means of Relief Branches and Auxiliary Pumps, it is of course entirely practicable to allow ftp, all the run‑off, both from excessive storms and from daily flow, to be discharged from any of these sections into Lake Pontchartrain. The drainage thus carried to the Lake would not be more polluted than that now delivered there, and whenever the Main Canal was completed for service, any nuisance would be at once abated, and the operation of the system could, thereafter, proceed in accordance with the completed plan, and the drainage be delivered into Lake Borgne.

 p40  While the ultimate construction of the Main Canal to its outfall through Bayou Bienvenu, into Lake Borgne, is an essential feature of the plan, its completion as a continuous channel of discharge may, if time or means are wanting, be postponed, and only such parts of its length as are necessary to convey the run‑off from the several sections to the nearest pumping stations, or to serve for storage purposes need be built until it is found convenient or necessary to do so. But whatever parts of it are undertaken should be made of the ultimate cross-section required, and all parts, at least between the New Canal and St. Bernard avenue, should be lined when they are constructed.

In general, all canals, branches and drains between the river and the Main Canal, should be lined with Masonry, and many of them covered with the street pavements; but those between the Main Canal and the Lake may be left without lining for years to come.

The enlargement of existing canals between the Main Canal and the Lake, as well as the cutting of new ones, or their subsequent enlargement, can mostly be done with dredging machinery, and the total cost should not be increased by undertaking the work in instalments, that is, by opening canals of moderate sizes at first, and afterwards enlarging them.

Canals and drains between the Main Canal and the river should, in general, be lined as they are built, though the covering of the larger ones may be omitted without impairing their efficiency as drains. In some cases, where they occupy narrow streets, the absence of covering would result in considerable public inconvenience and, in a few instances, might leave such streets useless as avenues of travel, which, presumably, could not long be tolerated. It would, therefore, appear proper to prosecute the work on most of the canals and other conduits between Broad street and the river, under specifications requiring them to be lined and covered; and the estimates hereinafter presented contemplate such lining, except in certain specified cases, and the covering of all drains between Claiborne street and the river, with certain others mentioned.

It will of course be necessary for public convenience to build bridges at numerous points across all uncovered canals and branches, but as this work should not in any way increase or diminish the capacity of the channels for drainage, it is considered as forming no essential part of the plan, and its cost is not included in the estimates.

Care should be taken that whatever bridges are built shall not obstruct the free flow of the Canals, and as far as possible all bridges crossing the larger Canals and Branches, especially on the Lake side of the Main Canal, should be so constructed as to facilitate the passage of dredge boats.

Since the run‑off which the drains and branches are separately designed to carry cannot be expected to reach the pumping stations to which they are tributary simultaneously with full volumes, it follows, as already stated, that the maximum capacity of the plant at any station may be less than that which would be required to pump the  p41 sum of the several rates of run‑off which may be delivered into the Main Canal. The pumping plant as first installed, therefore, need not be of full aggregate capacity, and for the further reason that, until larger areas of the city are paved and improved the ultimate capacity cannot be called for, even though the entire system of canals and drains were complete, and, also, that it cannot be presumed that the entire plan will be put under construction at once, or that its execution, even when undertaken, will be completed so rapidly as to make the full-powered plant an early necessity.

It would appear to be good policy to install pumping plants at most of the stations, only as fast as it may be found necessary to keep pace with the construction of the canals, drains, etc., as they are undertaken. The stations should be so designed that pumps comparatively small in capacity, or in number, merely effectively installed at first, and subsequently increased in capacity or number as occasion arises, and to any required extent.

For reasons stated on page 36, the estimates hereinafter ZZZ preed include provision for a Pumping Plant of a capacity to discharge approximately two-thirds of the aggregate of maximum run‑offs for which the drains and canals are designed; but the instalment of the plant to any such extent cannot be recommended until experience proves its necessity.

That part of the Second Section lying between Broad street and the river, on account of the concentration there of improved properties, paved streets and business houses, and of its central position with reference to the most densely inhabited area of the city, is now more urgently in need of improved drainage than other localities, and it is evident that the benefits to be derived from the execution of the plan, would be of greater immediate public value there than in any other section of the city. It hence suggests itself that this section may properly receive the first attention in the prosecution of this work, and a special estimate of cost has accordingly been prepared for it, so that, in case the City Council should desire to undertake this work, before arranging for the execution of other parts of the plan, it may proceed intelligently.

The relative order of importance, for the execution of the several parts proposed in the Second Section, is as follows:

1st. The construction of the Pumping Stations, Nos. 2 and 7, with the improvement of the Relief Branch Canal connecting these Stations.

2d. The construction of the St. Louis Branch Canal with lining and covering, or the acquirement and adaptation of the Carondelet Navigation Canal for drainage purposes set out Broad street.

3d. The Main and Branch Drains between Broad street and the river, to be lined and covered.

 p42  4th. The improvement of street grades and gutters. Such improvements, however, should not be delayed on account of the non-completion of other parts of the work, though it can accomplish little of itself in the way of drainage, except to relieve one locality by flooding another.

5th. The improvement of the Orleans Relief Outfall Canal.

6th. The construction of Main and Branch Drains between Broad street and the lake.

7th. The construction of the Main Canal and its connection with the sections above and below.

The work in other sections may be prosecuted in any order, or at any time, as it may be found most convenient. Whatever is done towards carrying out the plan in any section, cannot be injurious to the interests of other sections, whether or not they are directly benefited.

The First Section has the largest area, and, at present, its tendency towards increase in population and improvement, is probably more apparent than that of the other sections. But whether or not this tendency will continue as notably in the future as in the past cannot be predicted. A part of the drainage under existing arrangements, is discharged into the New Orleans Navigation Canal, a condition of affairs which will probably require change, and some work under the new plan may soon be demanded for that purpose.

The work in the Algiers Section, on account of its comparatively small size and cost might be done with less means than would suffice for much effective work in other sections, and hence might be undertaken at an early date.

In the Third, Fourth and Fifth Sections, the situation and conditions are so similar, as to offer, at this time, no suggestion of priority in date, or of limit in the extent to which work should be undertaken.

Part VI
Estimates of Cost

Your Committee has considered it expedient to prepare two estimates. The first is for the whole area to be drained, and for the ultimate and entire completion of the system, with provisions for any extension or improvement that may be required during the next fifty years. The cost of each section is estimated separately. In the First Section, the canals and drains on the River-side of Claiborne Street are lined, while the Claiborne Canal and all canals and drains in the rear of it are unlined. In the Second and Third Sections the Main Canal on Broad Street and all canals and drains on the River-side thereof are lined, and all on the Lake-side are unlined. In the Fourth Section all canals and drains on the River-side of Claiborne Street are lined, while the Claiborne Canal and all canals and drains on the Lake-side thereof are unlined. In the Fifth Section all canals and drains are unlined. In Algiers the Eliza and Vallette street drains are lined. The other canals and drains in this section are unlined.

The second estimate is for carrying out the recommendations made on Page 41, namely for the early improvement of parts of the Second Section to an extent which may be within the present financial ability of the city. Approximate Estimate of Cost of Drainage System

Approximate Estimate of Cost for the Improvement of the Second Section as recommended:

Respectfully submitted, zzz The surveys, leveling, rain-fall and discharge gaugings, computations, mapping, etc., were executed by the Topographical Survey Department, under the direction of L. W. Brown, City Engineer. Engineering Staff: AR Littlejohn, 1st Asst. Engineer, WC Kirkland, Asst. Engineer, AL Black, Asst. Engineer, WT Crotts, Asst. Engineer, EL Lambert, Asst. Engineer, JF Dupuy, Asst. Engineer, AF Theard, Draughtsman, B. Shall, Computer. Appendices Appendix I Definitions and Descriptions of Names and Terms applied to different parts of the work

"Drainage Districts" refers to the sub-divisions of the city with reference to the existing drainage system, as shown on Plate III. The city is now divided into three districts, known as the First, Second, and Third Drainage Districts.

"Drainage Sections" refers to the proposed sub-divisions of the city into drainage areas, and conforms to the proposed drainage plan, as shown on Plate IV. There will be six of these sections, to be known as the First, Second, Third, Fourth, Fifth and Algiers Sections. The area comprised in each section being that which will be drained by each of the five Main Pumping Stations, located on the Main Canal, as also one in Algiers.

The Draining Machines of the present system are five in number. They are designated by the names London, Orleans, Bienville, Melpomene and Dublin, and are located as shown on Plate III.

The Pumping Stations of the proposed system are nine in number, and are known as No. 1, located on Broad street, at the New Orleans Navigation Canal; No. 2, located at the intersection of Broad and St. Louis streets; No. 3, located at the intersection of Broad street and St. Bernard Avenue; No. 4, located at the intersection of Florida Avenue and La­fayette Avenue; No. 5, located at the intersection of Jourdan Avenue and Florida Avenue; No. 6, an auxiliary station, located at the intersection of Metairie Ridge and Upper Protection Levee; No. 7, an auxiliary station, located at the intersection of Taylor avenue and Orleans street; No. 8, an auxiliary station, located at the intersection of London and Monroe Avenues, and No. 9, located at the intersection of Canal avenue and Lawrence Street, in the Algiers Section.

"Cairo Datum," abbreviated "C. D.", refers to a plane 21.26 feet below Mean Gulf Level, and is the datum to which all elevations are referred.

"Main Canal" refers to the proposed Canal on Broad street, Hope street, and Florida Avenue from the Intersection of Nashville Avenue and Claiborne street to Pumping Station No. 5.

"Branch Canals" refers to all Canals discharging direct into the Main Canal.

"Main Drains" refers to conduits discharging into the Branch Canals.

"Branch Drains" refers to conduits discharging into Main Drains.

"Relief Branch Canals" refers to those Canals which lead from the Pumping Stations, located on the Main Canal, to the Auxiliary Stations, and which are used for a double purpose, namely, as Branch Canals during dry weather, and light storms, discharging into the Main Canal, and as Relief Canals during heavy storms, delivering the water to the Auxiliary Pumping Stations.

"Main Outfall Canal" refers to the Canal delivering the water from the Pumping Station on Florida Avenue at the intersection of Jourdan Avenue to the Bayou Bienvenu.

"Relief Outfall Canals" refers to the Canals delivering water from the three Auxiliary Pumping Stations, as also from Station No. 4 to Lake Pontchartrain.

"Street Gutters" refers to the small conduits, which may be covered or uncovered, collecting the water from the street and discharging into the Branch Drains.

"Run‑Off" refers to the rate of delivery of precipitation into the Canals and Drains.

"The Run‑Off Curves" on Plate VIII show in cubic feet per second, the volume of the run‑off which the proposed system is designed to effectively handle, from surfaces having different areas, slopes and density of population.

The word "Zone," where used in connection with this report, refers to the comparative impermeability of the surface of the ground.

"Zone A," refers to the densely improved sections, such as the territory embraced between the River, Rampart, Toulouse and Delord streets.

"Zone B," refers to a territory of medium density as to improvements, such as is embraced between Washington, Felicity, the River and St. Charles streets.

"Zone C," refers to sparsely built territory where the houses are surrounded by large yards with little or no pavement, such as the territory between Washington Avenue, Audubon Park, the River and St. Charles street.

"Zone D," refers to rural or agricultural areas such as Audubon Park, or farming lands.

The word "Normal," as used in this report, for drainage discharge, refers to the conditions existing when little or no rain-fall occurs. Appendix II Statement of Measures which have been taken, from time to time, relative to the Improvement of the Drainage of the City of New Orleans, and a Description of its Existing Condition

At different times during the past forty years, efforts have been made towards the proper drainage of the city; but, with the exception of the work done between the years 1871 and 1873, nothing of any permanent value, or of a nature embra­cing the completion of any comprehensive or general system, has been executed. For this fact, in connection with a brief review of our present condition, the conclusion is most apparent that the improvement in the drainage of the city has not been co‑extensive with its commercial growth.

The earliest report on the subject of drainage, is that of the City Surveyor, Mr. Louis H. Pilié, to the Common Council, in 1857, which treats wholly of the improvement of the drainage of that portion of the church lying to the rear of Claiborne street. This report recommended the construction of a number of open canals for drainage, and of levees to protect the city from inundation by the lake. The report is not accompanied by any plan, and does not clearly state what disposal of the drainage he proposed, or what locations were chosen at that time for the machinery, necessary for lifting the water. It is, however, quite apparent that it was Mr. Piliqq's idea to deliver the drainage into Lake Pontchartrain. Previous to the date of Mr. Piliqq's report, the Legislature of the State of Louisiana had taken steps towards the drainage of the rear portion of the city, as will appear from the following quotation from his report:

No record is at hand to show that any practical results were obtained from the survey referred to.

The benefits that would accrue from the thorough drainage of the whole area occupied by the city, were appreciated forty years ago fully as much as now, as will appear by the following quotation from the same report:

The Legislature in 1858, 1859, 1861 and 1871, enacted laws relative to the drainage of the City of New Orleans.

 p48  Act No. 165 of the Legislature of 1858, relates to the dividing of the city into four drainage districts, and providing a commission for each district; and, also a mode of assessment for the operation of the same.

Act No. 179 of 1859 of the Legislature, amends Act No. 165 of 1858, by authorizing the issue of thirty year bonds, limiting the issue to $350,000 for any one of the four districts.

Act No. 57 of 1861 provides for the collection of assessments for drainage purposes.

Act No. 30 of 1871, authorizes a contract to be entered into by the City of New Orleans, with the Mississippi and Mexican Gulf Ship Canal Company, for the construction of levees to protect the city from overflow, and of canals and pumping machinery for the drainage of the city, the location of the levees and canals to be as may be determined by the administrators of the affairs of the city. This Act authorizes that the rate of charge for the work performed shall be fifty cents per cubic yard for all canals excavated, and fifty cents per cubic yard for all levees built.

In 1868, the City Surveyor, Mr. L. Surgi, submitted to the Common Council a possible relative to the drainage of the city. This report recommended the improvement of the existing condition of drainage by the construction of additional open canals, and improving the machinery. It does not contain any data as to the volume of water to be handled, or the point of outfall. In fact, the report merely recommends the enlargement and improvement of the existing canal system and drainage machines. In his report, Mr. Surgi refers to Lake Borgne and Bayou Bienvenu, as follows:

With a view of perpetuating historical matter, the following is quoted from Mr. Surgi's report:

In 1869, the Common Council, by Ordinance No. 1148, N. S., elected a Board of Engineers to mature and recommend some general plan for the present and future drainage of the City of New Orleans. This Board was composed of Messrs. Braxton Bragg, A. G. Blanchard, Richard J. Evans, John Roy, H. C. Brown, G. W. R. Bayley, L. Surgi, and J. A. D'Hémécourt. This Commission recommended, for immediate relief, the improvement of the drainage system as recommended in Mr. Surgi's report in the year previous, and above referred to; but added that the ultimate plan of drainage, should be by means of under­ground sewers, collecting the water and delivering into the river. This report was evidently compiled without any accurate knowledge either of the topography, or of the volumes of water to be handled. While it would not be impossible to collect the storm-waters in sewers and deliver the same to the river, it would be impracticable.

The work done by the Mississippi and Mexican Gulf Ship Canal Company in 1871, 1872 and 1873, under provision of Act No. 30, of 1871, was carried out  p49 under the direction of the City Surveyor, Mr. W. H. Bell, and was in accordance with what is known as the "Bell Plan." There is no complete description of the system as proposed by Mr. Bell to be found, but from such records as are available, it is evident the system proposed by him was for the delivery of the drainage of the main portion of the city directly into Lake Pontchartrain. Part of the system contemplated the construction of a substantial breakwater and levee along Lake Pontchartrain from the Upper Protection Levee to People's Avenue Canal, and locating along this revetment, the necessary pumping machinery to lift the water into the lake. It is also conclusively shown that Mr. Bell contemplated the repumping of the water, from the area of the city between the river and the ridge, in order to provide the necessary slope for its delivery through canals of practicable size, to the necessary slope for its delivery through canals of practicable size, to the machines placed at the lake for final disposal. Mr. Bell recommended Lake Borgne as the ultimate out‑fall of all the foul drainage of the city, as also on the delivery of the water to the machines located on the shore of Lake Pontchartrain, are fully set forth in the following letter:

In 1881, a communication was addressed to the Honorable Mayor and Administrators of the City of New Orleans by Mr. Joseph Jouet. The plan contemplated the construction of a large central canal, which would act as a main tail-race for all the drainage, to run from the Upper Protection Levee and connect with Bayou Bienvenu, through which all the drainage water of the City of New Orleans would be delivered to Lake Borgne.

In 1889, a plan for the drainage of the City of New Orleans was presented to the City Council by Mr. J. L. Gubernator, which, with some modifications, was submitted by him to the present Advisory Board. The general features of this plan are the delivery of the water into Lake Pontchartrain, the improvement of existing canals, the construction of a large number of additional open canals and the pla­cing of a large number of drain u machines.

The plan presented to the Advisory Board by Mr. S. D. Peters, is for the delivery of all the drainage of the city through a main central canal to Lake Borgne. The drainage received from the different areas of the city is to be pumped into this main canal, and the main canal relieved by a pump at its lower end. The general features of the plan presented by Mr. Peters are similar to those contained in Mr. Jouet's plan of 1881.

In 1890, the Orleans Levee Board offered a premium of $2500.00 for the best plan of drainage for the City of New Orleans. The only data which they could furnish those who desired to enter this competition, was a general plan of the city. No exact knowledge could be given as to topography, areas, hydrography, or other data essential for the formulation of an efficient plan. Although there were several plans submitted in response to the advertisement, none could be accepted, for the reason that there was no reliable knowledge of the factors which were essential in determining the value of any of the plans submitted.

The necessity of making investigations relative to the topography and hydrography of the city, for the purpose of formulating a plan of drainage, has long been appreciated and, in 1888, an endeavor was made in the Legislature to pass an act enabling this preliminary work to be executed. The City Engineer, B. M. Harrod, made strenuous efforts to secure the necessary funds from the City Council, but without success. An attempt to obtain the funds by private subscription  p51 from public spirited citizens, also failed, and no measures looking towards the execution of this very essential preliminary work, were adopted until September, 1892, when an ordinance was introduced in the Council appropriating $17,500.00 for the purpose. This step met with considerable opposition, principally due to the supposition that the investigation had been made by previous administrations, and that the data could be found. A rigid search was made for records of this nature, but without result. The necessity for obtaining this information was demonstrated to the Council, and the ordinance authorizing the work, and providing the funds therefor, was adopted by it in February, 1893. The work was inaugurated thereafter, with as little delay as possible.

As shown in the above statement of the various attempts that have been made relative to the improvement of the drainage of the City of New Orleans, no work of any magnitude has been done since 1872 and 1873, under what was known as the "Bell Plan."

As stated in the body of the report, the Canals and Draining Machinery have not sufficient capacity to deliver the water to the out-falls with such rapidity, as to avoid the inundating of large and valuable areas; in fact, the investigations which have been made show, that when working at their maximum capacity they are capable only of properly disposing of the run‑off from 1⁄100 of an inch rain-fall in 5 minutes, or 12⁄100 in one hour, which, in comparison to storms such as visited the City of New Orleans on August 13, 1894, is entirely inadequate. The water from this storm remained on a large territory of the city for a period of 72 hours before the existing machinery, working at its full capacity, removed same.

The existing system of drainage is composed, as stated in the body of the Report, of open canals receiving the water delivered from the higher portions of the city by the small street gutters, and conveyed by these open canals to the draining machines, which deliver the same into Lake Pontchartrain. These draining machines are four in number, and are located in the bottom of the basin between the river and the Metairie and Gentilly Ridges, excepting the London draining machine, which is located on Gentilly Ridge.

The Dublin draining machine is located at the intersection of 14th and Dublin streets, and has a maximum capacity to deliver 480 cubic feet of water per second, with a lift of five feet. This machine is composed of two wheels, one being 34 feet in diameter and 6 feet face and the other being 34 feet 4 inches diameter, with a face of 5 feet 9 inches.

The Melpomene draining machine is located at the intersection of Claiborne and Melpomene streets, and has maximum capacity to deliver 150 cubic feet of water per second, with a lift of 5 feet. This machine has only one wheel, which is 35 feet diameter, 4 feet 6 inch face.

The Bienville draining machine is located at the intersection of Hagan Avenue and Toulouse street, and has a maximum capacity to deliver 240 cubic feet of water per second, with a lift of 5 feet. This machine consists of two draining wheels, one being 28 feet 6 inches in diameter, 4 feet 4 inches face, and the other 34 feet in diameter and 7 feet face.

The London draining machine is located at the intersection of London Avenue and Gentilly Ridge, and has a maximum capacity to deliver 300 cubic feet of water per second, with a lift of 5 feet. This machine consists of two draining wheels, each of which is 35 feet in diameter and 4 feet 10 inches face.

 p52  There is located at the intersect into no Bayou St. John and Orleans streets a centrifugal pump, delivering into the lake through the same tail-race as the Bienville machine. This pump has a maximum capacity of 44 cubic feet of waterer second, with a lift of 5 feet.

The area of the city now drained is divided into three districts by the two Navigation Canals.

These districts are known as first, second and third, and embrace an aggregate of 13,557 acres. The location of these districts, as also of the draining machines, is shown on Plate III.

The area of the city now drained extends only from the River to the Metairie and Gentilly Ridges, and a portion of this territory is wholly undrained ZZZ raind and other portions, of considerable area, are but partially drained.

The first drainage district embraces that portion of the city between the River, Metairie Ridge, the two Navigation Canals, Julia and Toulouse streets and has an area of 2,170 acres which is tributary to the Bienville draining machine.

The second district embraces that portion of the city between the River, Metairie Ridge, Upper Protection Levee, New Orleans Navigation Canal and Julia street, and has an area of 7,709 acres which is tributary to the Dublin and Melpomene draining machines.

The third district embraces that portion of the city between the River, Gentilly Ridge, Carondelet Canal, Bayou St. John, Toulouse and Elysian Fields streets, also between Elysian Fields and Poland streets from the River to Claiborne street, aggregating an area of 3,740 acres, which is tributary to the London draining machine and the Orleans pump.

The section of the city known as algiers, situated on the right bank of the river, has no drainage system.

As above noted, the total area of the city on the left bank of the river now drained has an aggregate area of 13,357 acres, which, as shown, is very imperfectly drained, and is about one-half of the area which the plan proposes to thoroughly drain, the aggregate area of which is 24,932 acres including Algiers.

The draining Machinery, with the exception of the Orleans pump, has been in service for upwards of forty (40) years, and is consequently primitive and not economical in its operation.

Considering the matter from every point, our present situation as to drainage in conjunction with the topographical and hydrographical conditions, renders the formulating of a thoroughly efficient and comprehensive system of drainage for the city an unique and intricate problem, and, perhaps, is unparalleled in this country or Europe, and the solving of the problem renders absolutely necessary a most careful and rigid investigation into all of the conditions bearing on the subject. Appendix III Topographical Survey

The topographical survey was started in July, 1893. The preliminary work had been well advanced, when, on September the 8th, it was stopped by an injunction issued by the Civil District Court, and not resumed until about the middle of December, 1893, since which time it has proceeded uninterruptedly, all the field-work being completed about the first of January, 1895.

A complete survey of the city has been made, and embraces the area bounded by the Mississippi River, Lake Pontchartrain, the Upper Protection Levee, People's Avenue Canal from Lake Pontchartrain to Florida Avenue, Florida Avenue from People's Avenue to the lower limits of the city, and the latter from Florida Avenue to the Mississippi River, and also the principal portion of Algiers. This survey was made by the establishment of carefully measured base lines around and within the area. The lines which have been traversed aggregate more than one hundred and fifty miles in length, and are as follows:

around the entire area on the left bank, as above described.

on Washington street, from the River to Carrollton avenue.

on Carrollton avenue, from the River to Metairie Ridge, near the Lower City Park, and extending to and crossing Bayou St. John at Marigny avenue, thence down and along Marigny avenue to elysian Fields street, and thence to the intersection of Florida Avenue and People's Avenue Canal.

A line on Tenth and Claiborne streets, commencing at the Upper Protection Levee and extending throughout the whole length of Claiborne street to Poland street.

A line on Elysian Fields street, from the River to the Lake.

A line on Broad street, from Julia street to Marigny avenue.

A line on esplanade avenue, from the River to Bayou St. John.

A line on London avenue, from Marigny avenue to the Lake.

A line on St. Peter street, from the River to Carrollton avenue, thence along the Orleans tail-race to the Lake.

A line on Julia street, from the River to Rampart street, and thence along the New Orleans Navigation Canal to the Lake.

A line on Seventeenth street, from Carrollton avenue to Metairie Ridge and thence along Metairie Ridge from the Upper Protection Levee to esplanade avenue.

A line on St. Charles avenue, from Carrollton avenue to Julia street.

A line on St. Claude street, from Elysian Fields street to the lower limits of the city.

A line on Felicity Road, from the River to Claiborne street, and thence along the Melpomene Canal to the intersection of Washington Shell Road.

A line on Lowerline street, from the River to Claiborne street.

A line on Walnut street, from the River to Ouachita street.

A line on Claiborne street, from the River to St. Charles avenue.

A line on Webster street, from the River to st. Charles avenue.

 p54  on Henry Clay avenue, from st. Charles avenue to Claiborne street.

A line on Peters avenue, from the River to Hector street.

A line on Joseph street, from the River to St. Charles avenue.

A line on Octavia street, from St. Charles avenue to Arcadia street.

A line on Valmont street, from the River to Breslau street.

A line on Milan street, from st. Charles avenue to Claiborne street.

A line on General Taylor street, from the River to St. Charles avenue.

A line on Amelia street, from the River to Claiborne street.

A line on Delachaise street, from the River to Claiborne street.

A line on Toledano street, from the River to Claiborne street.

A line on Harmony street, from the River to Magnolia street.

A line on First street, from the River to st. Charles avenue.

A line on Philip street, from the River to Claiborne street.

A line on St. Andrew street, from the River to Claiborne street.

A line on La­fayette avenue, from the River to Josephine street.

A line on La­fayette street, from the River to Claiborne street.

A line on Adams street, from the River to St. Claude street.

A line on Delery street, from the River to St. Claude street.

A line on Camp street, from Felicity Road to Delord street.

A line on St. Thomas street, from Robin street to Delord street.

A line on Robin street, from the River to St. Thomas street.

A line on Delord street, from St. Thomas street to Claiborne street.

A line on Locust street, from La­fayette street to Common street.

A line on Liberty street, from Julia street to Tulane avenue.

A line on Galvez street, from Julia street to St. Peter street.

A line along London Avenue Tail-race, from the Upper Protection Levee to the London Avenue Draining machine.

A line on St. Bernard avenue, from Claiborne street the Treasure street.

A line on Taylor avenue from Orleans street to Bayou St. John.

A line on Harrison avenue, from Orleans street to Bayou St. John.

A line was run along Gentilly Road, as also on the right bank (Algiers side) of the river from the nine mile point oppose Carrollton to Webster avenue below the Southern Pacific Railroad Depot. Also the necessary lines in Algiers to make a complete survey of same. The notes of all these surveys have been calculated by means of Latitude and Departure and plotted. All the note books of this work are indexed and filed.

Where necessary, off‑set lines from these traverse lines were made to enable a thoroughly correct map of the city to be plotted.

The entire city has been leveled over, bench marks were established at convenient points, and a record of the location and elevation of the same registered in a book of bench-marks. The whole work refers to Cairo Datum.

The leveling consisted in the main, of running each leading street and obtaining the elevation of the curb, gutter, center of street and property line at intersections, and in center of block, as also the elevation of the tops of all culverts, bridges and steam and street railroad tracks at intersections.

Lines on all of the existing drainage canals and tail-races were run, and the elevations obtained of the surface of the ground adjacent to the bank, the surface of the water and the bottom of the canals.

 p55  Profiles of all leading streets have been plotted and the originals carefully indexed and filed.  District.

 District. The following is a list of the profiles made: District.

 District. Adams (now Alabo) Street, from the River street to Claiborne Street, 3d District. Adams Street, from the River to Tenth Street, 7th District. Adele Street, from River street to St. Thomas Street, 4th District. Aline Street, from Tchoupitoulas street to St. Charles avenue, 6th District. Amelia Street, from Front street to Clara Street, 6th District. Anthonia Street, from St. Claude street to Marigny avenue, 3d District. Antonine Street, from Tchoupitoulas street to St. Charles avenue, 6th District. Andry Street, from the River to St. Claude Street, 3d District. Arts Street, from Urquhart street to Claiborne Street, 3d District. Aubrey Street, from Tonti street to Gentilly Road, 3d District. Audubon Street, from Water street to Claiborne Street, 6th District. Austerlitz Street, from the River to Perrier Street, 6th District. Arabella Street, from the River to St. Charles avenue, 6th District. Anthonia Street, from Marigny avenue to Gentilly Road, 3d District. Alexander Street, from the River to St. Charles avenue, 6th District. Atlantic Avenue, from Patterson street to Lapeyrouse Street, 5th District. Banks Street, from Prieur street to Murat Street, 1st District. Barracks Street, from the River to Broad Street, 2d District. Bartholomew Street, from the River to Claiborne Street, 3d District. Baudin Street, from Broad street to Murat Street, 1st District. Bellecastle Street, from the River to Perrier Street, 6th District. Bellechaise Street, from Tchoupitoulas street to St. Thomas Street, 1st District. Berlin Street, from the River to Claiborne Street, 6th District. Bienville Street, from the River to Metairie Ridge Street, 2d District. Bordeaux Street, from the River to St. David Street, 6th District. Broadway Street, from the River to Tenth Street, 6th District. Bourbon Street, from Canal street to Marigny avenue, from 2d and 3d Districts. Broad Street, from Julia street to Toulouse Street, 1st and 2d Districts. Broad Street, from Esplanade avenue to Lapeyrouse Street, 3d District. Burdette Street, from the River to Tenth Street, 7th District. Burgundy Street, from Canal street to Poland Street, from 2d and 3d Districts. Bourbon Street, from Marigny avenue to Gentilly Road, 3d District. Bolivar Street, from La­fayette street to Tulane avenue, 1st District. Bruxelles Street, from St. Bernard avenue to Gentilly Road, 3d District. Basin Street, from Julia street to Toulouse Street, 1st District. Benjamin Street, from Audubon Park street to Eleonore Street, 6th District. Bartholomew (now Bermuda) Street, from Levee street to Eliza Street, 5th Districts.º Bringier Street, from Madison street to Chestnut Street, 5th District. Bouny Street, from Levee street to Market Street, 5th District. Cadiz Street, from the River to Claiborne Street, 6th District. Caffin's Avenue, from the River to Claiborne Street, from 3rd District. Calhoun Street, from Tchoupitoulas street to St. Charles avenue, 6th District. Calliope Street, from the River to Claiborne Street, 1st District. Canal Street, from the River to Metairie Road, 1st and Second Districts. Celeste Street, from South Peters street to Felicity Street, 1st District. Chartres Street, from Canal street to Esplanade avenue, 2d District. Chippewa Street, from Felicity Road street to Louisiana avenue, 4th and 6th Districts. Clio Street, from Camp street to Claiborne avenue, 1st District. Clouet Street, from the River to Claiborne avenue, 3d District. Commercial Place Street, from Camp street to St. Charles Street, 1st District. Common Street, from the River to Protection Levee Street, 1st District. Columbus Street, from Rampart street to Broad Street, from 3d. District. Conery Street, from Prytania street to Carondelet Street, 4th District. Congress Street, from the River to Claiborne avenue, 3d District. Constantinople Street, from Front street to St. Denis Street, 6th District. Conti Street, from the River to Bernadotte Street, 2d District. Customhouse Street, from the River to Helena Street, 2d District. Cypress Street, from Liberty street to Galvez Street, 1st District. Carrollton Avenue, from the River to Canal Street, 7th District. Claiborne Street, from Julia street to Elysian Fields Street, 1st Street, from 2d Street, from and 3d Districts. District. Camp Street, from Canal street to Napoleon avenue, 1st Street, 4th and 6th Districts. Castiglione Street, from Broad street to Gentilly road, 3d District. Clinton Street, from Customhouse street to Bienville Street, 2d District. Chestnut from Felicity Road street to Audubon Park Street, 4th and 6th Districts. Constance from Felicity Road street to Audubon Park Street, 4th and 6th Districts. Canal (now Whitney) Avenue, from Patterson street to Lapeyrouse Street, 5th District. Chestnut (now Belleville) Street, from Patterson street to Lapeyrouse Street, 5th District. Columbus Street, from Madison street to Verret Street, 5th District. D'Abadie Street, from Galvez street to Gentilly road, 3d District. Dauphine Street, from Canal street to Delery Street, from 2d and 3d Districts. Delachaise Street, from the River to Claiborne avenue, 6th District. Delery Street, from the River to Claiborne avenue, 3d District. Delord Street, from Front street to Lee Circle Street, 1st District. Desire Street, from the River to Claiborne avenue, 3d District. Deslonde Street, from Royal street to St. Claude Street, 3d District. Dorgenois Street, from Julia street to Toulouse Street, 1st and 2d Districts. Dufossat Street, from the River to Long Street, 6th District. Dumaine Street, from Delord street to Canal Street, 1st District. Dryades Street, from Delord street to Canal Street, 1st District. Edmund (now Calhoun) Street, from St. Charles Avenue to Leonce Street, 6th District. Egania Street, from the River to Canal Street, 3d District. Eighth Street, from the River to Dryades Street, 4th District. Eleonore Street, from the River to St. Charles Avenue, 6th District. Elmire Street, from the River to Claiborne avenue, 3d District. Elysian Fields Street, from the River to Marigny Avenue, 3d District. Enghein Street, from the River to Claiborne avenue, 3d District. Erato Street, from the River to Claiborne avenue, 1st District. Esplanade Avenue, from the River to Bayou St. John Street, from 2d and 3d Districts. Euterpe Street, from Coliseum street to Liberty Street, 1st District. Elmira Street, from Patterson street to Lapeyrouse Street, 5th District. Feliciana Street, from St. Claude street to Claiborne avenue, 3d District. First Street, from the River to Claiborne avenue, 4th District. Flood Street, from the River to Claiborne avenue, 3d District. Forstall Street, from the River to Claiborne avenue, 3d District. Foucher Street, from Tchoupitoulas street to Green Street, 6th District. Fourth Street, from the River to Claiborne avenue, 4th District. France Street, from the River to Claiborne avenue, 3d District. Frenchmen Street, from Esplanade Avenue to Marigny Avenue, 3d District. Florida Street, from Gentilly Road street to esplanade Avenue, 3d District. Fourth Street (now Oaks) Street, from Jackson street to Lowerline Street, 7th District. Fortin Street, from Gentilly Road street to Mystery Street, 3d District. Franklin Avenue, from Market street to Lapeyrouse Street, 5th District. Gaiennie Street, from Pillie street to Camp Street, 1st District. Galvez Street, from Julia street to Toulouse Street, 1st and 2d Districts. Gasquet Street, from Basin street to Bernadotte Street, 1st District. General Taylor Street, from the River to Claiborne avenue, 6th District. Girod Street, from Levee street to North Liberty Street, 1st District. Gordon Street, from Chartres street to Villere Street, 3d District. Gravier Street, from the River to Pierce Street, 1st District. Galvez Street, from Esplanade Avenue to Lapeyrouse Street, 3d District. Hagan Avenue, from Julia street to Canal Street, 1st District. Hancock Street, from the street to Claiborne avenue, 3d District. Harmony Street, from the street to Claiborne avenue, 4th District. Havana Street, from Miro street to Gentilly Road, 3d District. Henderson Street, from Water street to Tchoupitoulas Street, 1st District. Henry Clay Avenue, from the River to Claiborne avenue, 6th District. Hillary Street, from the River to Sixth Street, 7th District. Hospital Street, from the River to Broad Street, 2d District. Howard Avenue, from Lee Circle street to Rampart Street, 1st District. Howell Street, from the River to Claiborne avenue, 3d District. Hunter Street, from Peter street to Tchoupitoulas Street, 1st District. Hurst Street, from Audubon Park street to Joseph Street, 6th District. Independence Street, from Peters street to Claiborne avenue, 3d District. Jackson Avenue, from the River to Claiborne avenue, 4th District. Jackson Street (now General Ogden) Street, from the River to Tenth Street, 7th District. Jeanne (now Alva) Street, Peters street to Claiborne avenue, 3d District. Jena Street, from the River to Claiborne avenue, 6th District. Joseph Street, from the River to Claiborne avenue, 6th District. Josephine Street, from the River to Claiborne avenue, 4th District. Jourdan Avenue, from the River to Marais Street, 3d District. Julia Street, from the River to Galvez Street, 1st District. Kerlerec Street, from Dauphine street to Dorgenois Street, 3d District. Kentucky Street, from the River to Villere Street, 3d District. La­fayette avenue, from St. Bernard Avenue to Broad Street, 3d District. Laharpe Street, from London Avenue to Gentilly Road, 3d District. Lapeyrouse Street, from Claiborne avenue to Gentilly Road, 3d District. Leonidas Street, from the River to Tenth Street, 7th District. Leontine Street, from the River to St. Charles Street, 6th District. Lesseps Street, from the River to Claiborne avenue, 3d District. Lizardi Street, from the River to St. Claude Street, 3d District. London Avenue, from St. Bernard Avenue to Broad Street, 3d District. Louisa Street, from the River to Claiborne avenue, 3d District. Louisiana Avenue, from the River to Claiborne avenue, 6th District. Lowerline Street, from the River to Tenth Street, 7th District. Lyons Street, from the River to Pitt Street, 6th District. London Avenue, from Marigny Avenue to Gentilly Road, 3d District. Laurel Street, from Louisiana Avenue to Audubon Park Street, 6th District. Lawrence Street, from Levee street to Chestnut Street, 5th District. LeBoeuf Street, from Patterson street to Eveline Street, 5th District. Madison (now Dante) Street, the River to Tenth Street, 7th District. Mandeville Street, from the River to Galvez Street, 3d District. Market Street, from Water street to Felicity Road, 1st District. Marigny Street, from Levee street to Prieur Street, 3d District. Mazant Street, from the River to Claiborne avenue, 3d District. Melpomene Street, from St. Thomas street to Claiborne avenue, 1st District. Milan Street, from Front street to Claiborne avenue, 6th District. Miro Street, from Julia street to Toulouse Street, 1st and 2d Districts. Monroe (now Tupelo) Street, from The street to Claiborne avenue, 3d District. Music Street, from Burgundy street to Celestine Street, 3d District. Montegut Street, from the River to Claiborne avenue, 3d District. Marengo Street, from the River to Claiborne avenue, 6th District. Magazine Street, from Canal street to Audubon Park Street, 1st Street, 4th and 6th Districts. Maurepas Street, from gentilly Road street to Esplanade Avenue, 3d District. Murat Street, from Canal street to Orleans Street, 2d District. Madison (now Brooklyn Avenue) Street, from Bringier street to Copernicus Street, 5th District. Market (now Opelousas Avenue) Street, from Levee street to Vallette Street, 5th District. Magellan Street, from Madison street to Verret Street, 5th District. Monroe (now Teche) Street, from Market street to Lawrence Street, 5th District. Napoleon Avenue, from the River to Claiborne avenue, 6th District. Nashville Avenue, from the River to Claiborne avenue, 6th District. Natchez Street, from Tchoupitoulas street to Camp 1st District. New Orleans Street, from Claiborne avenue to marigny Avenue, 3d District. Ninth Street, from the River to Magazine Street, 1st District. Notre Dame Street, from the River to Magazine Street, 1st District. Nunn Street, from South Peters street to Religious Street, 4th District. Nelson (now Serantine) Street, from Broad street to Gentilly Road, 3d District. New Orleans Street, from Marigny Avenue to Gentilly Road, 3d District. Octavia Street, from six thousand street to St. Charles Street, 6th District. Orange Street, from the River to Felicity Road, 1st District. Orleans Street, from Royal street to Bayou St. John Street, 2d District. Onzaga Street, from Prieur street to Gentilly Road, 3d District. O'Reilly Street, from Broad street to Gentilly Road, 3d District. Olivier Street, from the River to Market Street, 5th District. Palmyra Street, from Claiborne avenue to Bernadotte Street, 1st District. Pauline Street, from the River to Claiborne avenue, 3d District. Peace (now Kerlerec) Street, from Charles street to Bourbon Street, 3d District. Penniston Street, from Front street to Claiborne avenue, 6th District. Perdido Street, from St. Charles street to Hagan Avenue, 1st District. Perilliat Street, from Liberty street to Magnolia Street, 1st District. Peters Street, from Flood street to Barracks Street, 3d District. Peters Avenue, from the River to Bartholomew Street, 6th District. Philip Street, from the River to Claiborne avenue, 4th District. Pine Street, from Levee street to Zimple Street, 6th District. Piety Street, from the River to Claiborne avenue, 3d District. Pleasant Street, from the River to St. Charles Street, 4th District. Poeyfarre Street, from Tchoupitoulas street to Camp Street, 1st District. Poland Street, from the River to Claiborne avenue, 3d District. Polymnia Street, from Coliseum street to Dryades Street, 1st District. Port Street, from the River to Claiborne avenue, 3d District. Poydras Street, from the River to Broad Street, 1st District. Press Street, from the River to Broad Street, 3d District. Prytania Street, from Louisiana Avenue to Calhoun Street, 6th District. Pitt Street, from Louisiana Avenue to Audubon Park Street, 6th District. Paris Avenue, from St. Bernard Avenue to Gentilly Road, 3d District. Perrier Street, from Nashville Avenue to Audubon Park Street, 6th District. Pacific Avenue, from Patterson street to Lapeyrouse Street, 5th District. Race Street, from the River to Coliseum Street, 1st District. Rampart Street, from Calliope street to Poland Street, 1st Street, from 2d and 3d Districts District. Reynes Street, from the River to Villere Street, 3d District. Richard Street, from the River to Felicity Road, 1st District. Robert Street, from the River to Claiborne avenue, 6th District. Rocheblave Street, from Julia street to Toulouse Street, 1st and 2d Districts. Robin Street, from Levee street to Camp Street, 1st District. Royal Street, from Canal street to Poland Street, from 2d and 3d Districts. St. Andrew Street, from the River to Claiborne avenue, 4th District. St. Ann Street, from the River to Broad Street, 2d District. St. Anthony Street, from Burgundy street to marigny Avenue, 3d District. St. Bernard Avenue, from St. Claude street to Broad Street, 3d District. St. Bernard (now Allen) Street, from Claiborne avenue to Marigny Avenue, 3d District. St. Ferdinand Street, from the River to Claiborne avenue, 3d District. St. James Street, from the River to Felicity Road, 1st District. St. Joseph Street, from Delta street to Baronne Street, 1st District. St. Louis Street, from the River to Metairie Ridge Street, 2d District. St. Peter Street, from the River to Bayou St. John Street, 2d District. St. Philip Street, from the River to Bayou St. John Street, 2d District. St. Mary Street, from the River to Carondelet Street, 4th District. St. Thomas Street, from Felicity Road street to Toledano Street, 4th District. Sixth Street, from the River to Claiborne avenue, 4th District. Seventh Street, from the River to Locust Street, 4th District. Second Street, from the River to Claiborne avenue, 4th District. Short Street, from the River to Tenth Street, 7th District. Soniat Street, from the River to Story Street, 6th District. Soraparu Street, from the River to Annunciation Street, 4th District. Spain Street, from the River to Prieur Street, from 3d District. State Street, from the River to St. Charles Street, 6th District. St. Bernard (now Allen) Street, from Marigny Avenue to Gentilly Road, 3d District. St. Anthony Street, from Marigny Avenue to Gentilly Road, 3d District. St. Charles Avenue, from Julia street to Carrollton Avenue, 1st Street, 4th Street, 6th and 7th Districts. St. Bernard Avenue, from Broad street to Gentilly Road, 3d District. State Street, from St. Charles street to Victor Street, 6th District. Seguin Street, from Patterson street to Market Street, 5th District. Terpsichore Street, from the River to Magnolia Street, 1st District. Thalia Street, from the River to Claiborne avenue, 1st District. Theresa Street, from Tchoupitoulas street to St. Thomas Street, 1st District. Third Street, from the River to Claiborne avenue, 4th District. Toledano Street, from the River to Claiborne avenue, 4th and 6th Districts. Tonti Street, from Julia street to Toulouse Street, 1st and 2d Districts. Toulouse Street, from the River to Metairie Ridge Street, 2d District. Triangle Street, from Front street to Peters Street, 1st District. Tricou Street, from the River to Claiborne avenue, 3d District. Tchoupitoulas Street, from Canal street to Audubon Park Street, 1st Street, 4th and 6th Districts. Thayer Street, from Patterson street to Lapeyrouse Street, 5th District. Union Street, from St. Charles street to Dryades Street, 1st District. Union (now Touro) Street, from Peace street to Gentilly Road, 3d District. Upperline Street, from the River to Claiborne avenue, 6th District. Upperline Street, from the River to Tenth Street, 7th District. Ursulines Street, from the River to Rendon Street, 2d District. Urania Street, from Coliseum street to Felicity Road, 1st District. Valence Street, from the River to Claiborne avenue, 6th District. Valmont Street, from the River to Leonie Street, 6th District. Valette the River to Lapeyrouse Street, 5th District. Verret Street, from the River to Lapeyrouse Street, 5th District. Walnut Street, from the River to Claiborne avenue, 6th District. Warsaw Street, from St. Bernard avenue to Valette Street, 3d District. Washington Avenue, from the River to Claiborne avenue, 4th District. Washington (now St. Roche) Avenue, from Chartres street to Celestine Street, 3d District. Webster Street, from Tchoupitoulas to St. Charles avenue, 6th District.

A map on a scale of 600 feet to the inch has been plotted from the actual traverse lines as above enumerated, on which map has also been placed, one foot contour lines. There has also been made a map of each of the proposed drainage sections, showing the location of the conduits and area of different zones tributary to same. Appendix IV Rain-fall gauging

For the purpose of obtaining accurate information regarding the precipitation, six "Frieze" self-registering rain gauges were purchased and placed at selected points throughout the city. These gauges automatically register the precise time and rate of precipitation, the amount being registered so as to read to hundredths of an inch. The total amounts recorded by the gauge were checked by actual measurement with a graduated stick. Plate VI shows the records of the rain storms which occurred on April 24th, July 4th, July 14th and August 13th, 1894. The locations selected for the gauges were such as to furnish the rate and intensity of precipitation in the different parts of the area now subject to drainage. One gauge was placed in Audubon Park near the river, one at the Dublin Avenue Draining Machine, one at the London Avenue Draining Machine, one at the corner of France and Levee streets, one at the City Hall, and one was located at West End, but was afterwards removed and placed at the corner of Magazine and Berlin Streets. These gauges were all installed, tested and in thorough operation by April 1st, 1894.

The necessity of having several gauges for the purpose of obtaining the average precipitation on a large area, is of paramount importance, as storms even of a general character, vary largely in precipitation, even within a small area and in New Orleans a large proportion of the storms are limited in area and do not simultaneously extend over the whole city. The records of precipitation at different points in any territory enable the direction and intensity of the storm to be observed and also indicate the sections which were visited by the greatest intensity during any one storm.

The records of rain-falls by these instruments have been carefully preserved and the volume of precipitation on the different areas calculated and tabulated.

Plate VII represents graphically the fall in inches and the duration of several storms of intense precipitation which have occurred in the City of New Orleans between April 1st and December 31st, 1894, the date of the several storms being marked on the plate.

Table I is a list of the storms which have occurred in the City of New Orleans between April 1st and December 31st, 1894, where the total precipitation did not exceed half an inch. This table also shows the maximum precipitation in five minutes, the maximum rate of precipitation per hour, the total precipitation in inches, the duration of storm, and the date.

Referring to this table it will be noted that the rate of precipitation is in many instances very great in comparison to the volume, as in the storm of April 25th when, with a total precipitation of 0.33 of an inch, the rate was 2.4 inches per hour; and five of these storms having a total precipitation of less than 0.5 of an inch had a rate of 1.8 inches per hour and upwards.

Table II is a list of the storms which have occurred in the City of New Orleans between April 1st and December 31st, 1894, having total precipitations  p62 exceeding 0.5 of an inch and shows the date of maximum intensity in five minutes, maximum rate per hour, maximum precipitation per hour, total precipitation and duration of storms. Of the twenty-four storms referred to in this table, eleven had a rate of precipitation exceeding three inches per hour. The storm of August 13th had a rate of precipitation of 6 inches per hour, and that of April 24th a rate of 5.4 inches per hour. These tables were compiled from gaugings made at the City Hall Station.

The greatest rate of precipitation on July 4th, as registered at the Park Station, was 7.2 inches per hour. It will also be noted that the greatest precipitation in one hour occurred on August 13th, when it was 2.75 inches, but the greatest intensity of this storm was at the rate of 6 inches per hour. On April 24th, with a maximum rate of 5.4 inches, the total precipitation in one hour was 1.9 inches, and on July 14th the maximum rate was 4.8 inches, and the total precipitation in one hour was 1.82 inches.

Table III is a list of storms of great intensity which have occurred in the States of Louisiana and Mississippi between the years 1872 and 1894.

Table IV is a list of storms which have occurred in the City of New Orleans from 1871 to 1894, in which the total precipitation exceeded 2.5 inches in twenty-four hours, as gauged by the New Orleans Station of the U. S. Signal Service and Department of Agriculture, Weather Bureau.

Table V is a list of storms which have occurred in the City of New Orleans from 1871 to 1894 in which the rate of precipitation exceeded one inch per hour, as gauged by the New Orleans Station of the U. S. Signal Service and Department of Agriculture, Weather Bureau. Appendix V Run‑off Gauging

In order to obtain the volumes of water discharged at the different draining machines, flumes were established in the out‑fall canals of the present drainage stations, for the purpose of obtaining uniform sections through which all the water lifted by each machine would pass. The dimensions of these flumes were such as to suit the existing conditions at the different stations:

Across the top of each flume a suitable wharf was placed for the operator, provided with a strong substantial rail, which rail was graduated to facilitate the use of the meter. The gauging was performed with a "Price" current meter, and the operation was as follows:

The elevation of the water in the drainage and out‑fall canals was observed and noted every 30 minutes, the difference in elevation being the height to which the water was lifted. Each time the gauging was made, a cross-section of the bottom of the channel was carefully taken and plotted. The meter was then placed in position six inches below the surface of the water and moved across the canal at a uniform rate. After which, the meter was lowered six inches more or one foot below the surface and moved in the same manner, and so on, the number of times necessary for the meter to be moved across the channel every 6 inches of its depths, and the calculation of velocity and discharge made in the usual manner, from the number of revolutions recorded by the register.

There was, also, located on each shaft, at each of the draining machines, a counter, which was constantly observed and recorded. The coal consumed was carefully weighed and a daily report made. The gauging of the discharge from the machines has been carried on very carefully from April 1st to December 31st, 1894, and all the varying conditions carefully noted, recorded and tabulated; and from the information thus obtained, a curve has been plotted from which can be obtained the discharge of the wheels, knowing the number of revolutions of the wheel and the elevation of the water in the inside and outside canals. These gaugings of the discharge of the machines were extremely arduous, as it was necessary for the work to be carried on continuously during and after rains, in order to obtain positive information of the amount of rainwater discharged, thus rendering it necessary for the men to remain at work day and night, oftentimes incessantly for periods of 36 hours.

The records of the gaugings of precipitation and discharge have been accurately compiled and tabulated, and graphical charts showing the amount of precipitation, in millions of cubic feet, falling on the area drained by each of the machines, have been prepared. These charts also show graphically the amount of water, in millions of cubic feet, discharged by each machine, the lift in feet and the coal consumed in tons.

 p64  Plate V is a chart showing graphically, from April 1st to December 31st, 1894, the volume of precipitation falling on the entire area of the city now subject to drainage, the volume discharged by all the draining machines, the duration of storms in hours, the lift in feet, the coal consumed in tons, and the total rainfalls in inches, as registered at the City Hall Station.

Table VI is a record of the gaugings from April 1st, to December 31st, 1894, of the total volume of precipitation and the total volume of discharge by the different draining machines for the entire area of the city now subject to drainage.

Table VII is a record of the gaugings from April 1st to December 31st, 1894, of the total volume of precipitation and discharge from the area now drained by the Bienville Draining machine, which area is designated as the "First Drainage District" on Plate III.

It will be observed from this table that the proportion of storm water pumped in the aggregate after deducting the daily or normal flow varies greatly with the character of soil, as to its degree of saturation and imperviousness, and with the intensity of rainfall, as shown by the following table:

The largest proportion of the precipitation ultimately discharged by the draining machines was during the months of July and August, when heavy rainfalls occurred nearly every day.

During the month of October, after deducting the normal flow, the zzz djh exceeded the total volume of precipitation due to the fact that this month was very dry and a famine of cistern water prevailed. To alleviate the situation in the district drained by the Bienville Machine an extensive use was made of the water from the water works to supply, through gutters, the sections not having mains and a most liberal use of hydrants where mains existed, so that the normal flow was very largely increased. For the months of November and December it was from similar causes, also increased, so that the results for October, November and December cannot be considered as furnishing proper proportions as only comparatively light rains occurred during these months, a consideration of the results can be properly omitted.

The results from the other six months can be assumed as giving a reasonable proportion, under varying conditions, of the precipitation ultimately discharged by the present system. It will be noted that

 p65  The soil during these four months was moderately saturated.

The soil during these two months was excessively saturated. During the two months of July and August it rained almost daily, but in July the daily rate of precipitation was more uniform than in August.

Table VIII is a record of the gaugings of the volume discharged by the several draining machines from the entire area of the city now subject to drainage, during a period of forty consecutive days, when no precipitation occurred. This Table also gives the volume of the average present normal discharge.

The area drained by the Dublin and Melpomene Stations (which stations act in conjunction in draining the area) has an aggregate of 7,709 acres. The present daily flow from this area, as determined by the foregoing table, equals 3.56 cubic feet per acre per hour.

The area drained by the Bienville draining machine (which is independent) has an aggregate of 2,170 acres. The daily flow, as ascertained from Table VIII would therefore amount to 20.8 cubic feet per acre per hour.

The area drained by the London Avenue Station has an aggregate of 3,478 acres. The daily flow from this area, as determined from Table VIII equals 5.8 cubic feet per acre per hour.

The ultimate daily flow to be discharged by the proposed system, will not be at a rate per acre, in excess of the daily flow now reaching the drainage stations. The sewerage system will be completed at an early date, and will receive a considerable portion of the water which now constitutes the daily flow, and an efficient system of drainage will deliver the run‑off into the outfall canals quickly, not allowing the water to remain on the soil, as it now does. This will very materially reduce the amount of percolation and the seepage forming a large part of the present normal or dry-weather flow.

The conclusion reached concerning the volume of daily flow to be handled is, that from the commercial part of the city, it will not exceed twenty (20) cubic feet per acre per hour, and, from the suburban and vacant portions of the city, five (5) cubic feet per acre per hour. On this basis, the system is arranged for the removal of the daily flow, which aggregates, at the different Pumping Stations, the following quantities:

Pumping Station No. 1 receives the drainage from 8,887 acres, aggregating 44,435 cubic feet to be delivered per hour.

Pumping Station No. 2 drains 5,384 acres (of which 1200 acres are allowed for at the rate of 20 cubic feet per acre per hour, aggregating 24,000 cubic feet, and 4184 acres at 5 cubic feet per acre per hour, aggregating 20,920 cubic feet per hour), making the total flow which will be required to be delivered from the section 44,920 cubic feet per hour.

The area drained at Pumping Station No. 3 contains 4,682 acres, and will furnish a normal flow of 23,410 cubic feet per hour.

Pumping Station No. 4 drains 2,153 acres, which will produce a normal flow of 10,765 cubic feet per hour.

Pumping Station No. 5 drains 2,878 acres, which will produce 14,390 cubic feet of normal flow per hour.

Algiers Station drains 948 acres, which will produce a normal flow of 4,740 cubic feet per hour. Appendix VI Tables Table I.— Storms occurring in New Orleans between April 1st and December 31st, 1894, having a total Precipitation of less than 0.50 inches; showing date, maximum intensity in five minutes, maximum rate per hour and duration of storm, as automatically registered at City Hall Station.

Table II.— Storms occurring in New Orleans between April 1st, and December 31st, 1894, having a total Precipitation exceeding 0.50 inches showing date, maximum intensity in five minutes, maximum rate per hour, duration of storm and maximum precipitation in inches in one hour, as automatically registered at City Hall Station.

Table III.— Showing date, duration, amount in inches and maximum intensity per hour of excessive precipitation in Louisiana and Mississippi, from 1872 to May, 1894, gauged by the United States Department of Agriculture — Weather Bureau.

Table IV.— Showing date and total precipitation of storms which have occurred in New Orleans, from 1871 to April, 1894, where the total precipitation was in excess of 2.5 inches in 24 hours, gauged by the New Orleans Station of the United States Department of Agriculture — Weather Bureau.

Table V.— Showing date and total precipitation of storms, which have occurred in New Orleans from 1871 to April, 1894, when the rate of precipitation exceeded 1 inch per hour, gauged by the New Orleans Station of the United States Department of Agriculture — Weather Bureau.

Table VI.— Record of gaugings from April 1st to December 31st, 1894, of total volume of precipitation and total volume of discharge from the entire area of the city now subject to drainage, the area aggregating 13,357 acres.

Table VII. — Record of gaugings from April 1st to December 31st, 1894, of total volume of precipitation, and total volume of discharge from area drained by the Bienville Draining Machine; the area aggregating 2,170 acres. Table VIII.— Records of gaugings of volume of water discharged by the different draining machines, from September 28th to October 27th, or for forty consecutive days, during which no precipitation occurred.

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Thayer's Notes:

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