38th Congress, | 
Is/ Session. J 
SENATE. 
( Mis. Doc. 
) No. 83. 
IN THE SENATE OF THE UNITED STATES. 
April 15, 1864.-Resolved, That one thousand extra copies of the Report of the Wash- 
ington Aqneduct be printed; five hundred for the use of the Interior Department and five 
hundred for the use of the Senate. 
Mr. Morrill, from the Committee on the District of Columbia, presented the 
following supplemental report of the Engineer of the Washington Aqueduct, 
which was ordered to be printed. 
SUPPLEMENTAL REPORT OF THE CHIEF ENGINEER OF THE WASHINGTON 
AQUEDUCT. 
Department of the Interior, 
Office of the Washington Aqueduct, February 22, 1864. 
Sir: The Senate having, on February 2, 1864, passed the following 
resolution, to wit: "Resolved, That the Committee on t e District of 
Columbia be instructed to inquire into the subject of the Washington 
aqueduct, and the necessity f >r fu ther appropriations therefor; and into the 
subject of sewerage in the city of Washington, with power to send for persons 
and papers." 
And the committee having expressed a desire to make a thorough investiga- 
tion of the manner in which all pa-t appropriations have been expended; and 
also of the details and explanations of the estimates, subrnitti d in the last 
annnal reports from your department, of the amount required for future ex- 
penditures, in order that they may form an intelligent opinion as to the neces- 
sity for any further appropriations by Congress, I have, under your instructions, 
prepared the following 
SUPPLEMENTAL REPORT, 
in addition to, or in further explanation of the last annual report from this 
office, dated October 1, 1863, in relation to such matters as may come within 
the scope of the investigations under the aforesaid resolution. 
It is assumed that the general objects of the investigation are to ascertain, 
first, whether the past appropriations have been expended in accordance with 
the directions of Congre'ss, as expressed in the laws passed in relation to the 
Washington aqueduct; second, whether these expenditures have been made 
in a manner best calculated to secure, with reasonable economy, the objects for • 
which the work was undertaken by the government; and, third, whether any, 
and, if so, what amount of further appropriation is now required for the proper 
protection, prosecution, and completion of the work. 
1. Laws of congress relating to the Washington aqueduct. 
The first enactment by Congress in relation to this work will be found on 
page 92, volume 10, Statutes at Lirge, in the general appropriation bill passed 
April 31, 1852, which reads as follows : 2 
WASHINGTON AQUEDUCT. 
" To enable the President to cause the necessary surveys, projects, and esti- 
mates to be made for determining the best means of affording the cities of 
Washington and Georgetown an unfailing and abundant supply of good and 
wholesome water, report thereof to be made to Congress at its next session, the 
sum of five thousand dollars, or so much thereof as may be found necessary." 
The second enactment will be found on page 206, volume 10, Statutes at 
Large, in the general appropriation bill, passed March 3, 1853, which reads as 
follows: 
" To be expended under the direction of the President of the United States, 
for the purpose of bringing water into the city of Washington upon such plans 
and from such places as he may approve, one hundred thousand dollars: Provided, 
That if the plan adopted by the President of the United States should require 
water to be drawn from any source within the limits of Maryland, the assent of 
the legislature of that State shall first be obtained." 
The third enactment will be found on page 664, vol. 10, Statutes at Large, in 
the general appropriation bill, passed March 3, 1855, which reads as follows: 
" For continuing the work on the Washington aqueduct, two hundred and 
fifty thousand dollars." 
The fourth enactment, will be found on page 86, vol. 11, Statutes at Large, in 
the appropriation bill for certain civil expenses, passed August 18, 1856, which 
reads as follows: 
" For paying existing liabilities for the Washington aqueduct, and preserving 
the work already done from injury, such sums of money as shall be necessary, 
not exceeding two hundred and fifty thousand dollars." 
The fifth enactment will be found on page 225, vol. 11, Statutes at Large, in 
the appropriation bill for certain civil expenses, passed March 3, 1857, which 
i;eads as follows: 
"For continuing Washington aqueduct, one million dollars." 
The sixth enactment will be found on page 323, vol. 11, Statutes at Large, in 
the appropriation bill for certain civil expenses, passed June 12, 1858, which 
reads as follows: 
"For the completion of the Washington aqueduct, eight hundred thousand 
dollars; and in addition thereto, so much of the appropriation of two hundred 
and fifty thousand dollars 'for paying existing liabilities for the Washington 
aqueduct, and preserving the work already done from injury,' contained in 'An 
act making appropriations for certain civil expenses of the government for the 
year ending thirtieth June, eighteen hundred and fifty-seven,' approved 
eighteenth August, eighteen hundred and fifty-six, as may not be required for 
said purposes." 
The seventh enactment will be found on page 435, vol. 11, Statutes at Large, 
passed March 3, 1859, entitled " An act to provide for the care and preservation 
of the works constructed by the United States for bringing the Potomac water 
into the cities of Washington and Georgetown, for the supply of said water for 
all governmental purposes, and for the uses and benefits of the inhabitants of 
said cities." No appropriation is made in this act, and it is too lengthy for in- 
sertion here. Some of its provisions have been amended and repealed; but 
many of them are important, and remain in force. It creates the office of 
"Engineer of the Potomac water works," and specifies the manner in which 
the inhabitants of Washington and Georgetown may be supplied " with Potomac 
water from the aqueduct mains or pipes now laid, or to be laid, in the streets 
and avenues by the United States," and provides: "That the cities of Wash- 
ington and Georgetown, respectively, shall have power to establish a complete 
system of sewerage in aid of the execution of this act." 
The eighth enactment will be found on page 106, vol. 12, Statutes at Large, 
in the appropriation bill for sundry civil expenses, passed June 25, 1860, which 
reads as follows: WASHINGTON AQUEDUCT. 
3 
"For the completion of the Washington aqueduct, five hundred thousand 
dollars, to be expended according to the plans and estimates of Captain Meigs, 
and under his superintendence: Provided, That the office of engineer of the 
Potomac water works is hereby abolished, and the duties shall hereafter be 
discharged by the chief engineer of the Washington aqueduct." 
The ninth enactment will be found on page 620, vol. 12, Statutes at Large, 
entitled "Joint resolution transferring the supervision of the Potomac water 
works to the Department of the Interior," passed June 21, 1862, and which 
reads as follows: 
" Resolved, 8fc., That the supervision of the Potomac water works be, and the 
same is hereby, transferred from the War Department to the Department of the 
Interior; and all unexpended money which has been heretofore appropriated, 
and all money which may be hereafter appropriated, for the completion of said, 
water works, shall be expended under the direction and supervision of the 
Secretary of the Interior." 
The tenth and last enactment will be found on pages 804 and 805, vol. 12, 
Statutes at Large, entitled " An act amendatory of an act entitled ' An act to 
provide for the care and preservation of the works constructed by the United 
States for bringing the Potomac water into the cities of Washington and George- 
town, for the supply of said water for all governmental and other purposes, and 
for the uses and benefits of the inhabitants of the said cities,' passed March 3, 
1863." 
No appropriation is made in this act, and it is too lengthy for insertion here. 
It provides for some details and omissions that were wanting in the act to which 
this is an amendment, with reference to levying and collecting taxes and water 
rents by the corporation, for the purpose of laying down water-pipes and erect- 
ing fire-plugs throughout the city of Washington ; and provides that the 
thus created " shall constitute a fund exclusively for the maintenance, manage- 
ment, and repair of the system of wat£r distribution." 
It may be proper to remark in this place, that some further legislation appears 
to be necessary, or the existing laws more rigidly enforced, with reference to the 
proper control of the distribution of the water throughout the city, in order to 
prevent unnecessary waste. 
The aggregate appropriations made by Congress in the foregoing enactments 
may be recapitulated as follows : 
April 31, 1852 
March 3, 1853 
100,000 
March 3,1855 
250, 000 
August 18, 1856 
.............. . . 
250,000 
March 3, 1857 
. 1, 000, 000 
June 12, 1858 . 
800, 000 
June 25, 1860 
500, 000 
Total 
. 2, 905, 000 
By reference to the foregoing legislation it would appear that, up to June 25, 
1860, Congress had never in terms restricted the expenditure of the appropria- 
tions to any particular plans, specifications or estimates, further than may be 
inferred from the first enactment, which authorizes the President " to cause 
surveys, projects, and estimates to be made for determining the best means of 
affording the cities of Washington and Georgetown an unfailing and abundant 
supply of good and wholesome water and from the second enactment, which 
provides that the amount therein appropriated shall " be expended under the 
direction of the President of the United States, for the purpose of bringing water 
into the city of Washington upon such plans and from such places as he may 
approve'' fyc. 4 
WASHINGTON AQUEDUCT. 
Tlie eighth enactment, passed June 25, I860, is more specific, and provides 
that the amount of five hundred thousand dollars therein appropriated shall "be 
expended according to the plans and estimates of Captain Meigs, and under 
his superintendence," ifc. It appears by reference to the report of Captain 
Meigs, (supposed to be dated October 1, 1861-see page 84, message and doc- 
uments, 1861-'62, part 2,) that the bill was approved and signed by the President, 
though in returning it to Congress he accompanied it with a message, with some 
remarks upon the conditions attached to this appropriation. 
On referring to this message, (see " Congressional Globe, part 4, appendix, 
1st session 36th Congress, 1859-'6O,") and perusing it carefully, I deem it so 
important, as constituting a component part of the past history of this work, 
that I have appended a full copy to this report.* 
It may be proper to state, in this connection, that the civil appropriation bill 
which contained the objectionable item referred to in the President's message 
was passed by Congress at the close of the session ; and, consequently, if the 
President had vetoed it on account of these objections, the entire bill would 
have failed to become a law. 
A perusal of the report of Captain Meigs, above referred to, and also of the 
inscriptions upon the aqueduct structures, and property connected therewith,! 
appear to indicate that Captain Meigs felt justified in the belief that he would 
remain in charge of the work until it was fully completed, in accordance with 
his plans and specifications. 
The annexed letter to the Secretary of the Interior, dated August 27, 1863,£ 
would also seem to indicate that, in the opinion of General Meigs, the plans, as 
designed by him, ten years since, for the work, are the best that can be devised, 
and that any departure from them will "require special legislation to legalize it." 
The following clause in the joint resolution passed June 21, 1862, to wit, 
and all unexpended money which has been heretofore appropriated, and all 
money which may be hereafter appropriated for the completion of said water 
works, shall be expended under the direction and supervision of the Secretary of 
the Interior," seems to repeal or annul the restrictions previously placed upon 
the expenditure, both with reference to " the plans and estimates of Captain 
Meigs," as well as to "his superintendence," and leaves the Secretary of the 
Interior responsible alone to Congress for the manner in which the work is con- 
ducted, and the money expended. 
2. PrOPRIETY'OF past and proposed expenditures. 
In the exercise of the authority, and acting under the responsibility, imposed 
upon him by Congress, the Secretary has directed and approved some changes, 
both in the theory of working the aqueduct and in some of the plans which 
were being executed when the work came under his supervision; some of which 
involve increased expenditures of money, and all of which, it is believed, will, 
when fully understood, meet with the approval of Congress. 
These changes are explained in the following extracts from the last annual 
reports of the Secretary of the Interior and the chief engineer of the Washing- 
ton aqueduct: 
Extract from the last annual report of the Secretary of the Interior, in relation 
to the Washington aqueduct. 
"The work on the Washington aqueduct has progressed, in pursuance of the 
act of Congress transferring the same to this department, with but slight excep- 
tions, and the water of the Potomac river has been this day introduced into the 
reservoirs. The walls and. banks of the distributing reservoir were designed, by 
a See Appendix A, page 22. 
t See Appendix B, p. 24. 
| See Appendix C, p 26. WASHINGTON AQUEDUCT. 
5 
the engineer who projected the aqueduct, to be protected by broken stone, and 
a contract was made and the work commenced on that plan; but it appeared 
to me to be so unsubstantial and insufficient for the purpose that I caused an 
inquiry to be made as to the manner of protecting similar embankments in other 
localities, and found that, with but few if any exceptions, the walls were lined 
with solid stone masonry, laid in the best of cement. Influenced by the exam- 
ple and experience of others and by the advice of eminent engineers, I directed 
a thin dressing of broken stone to be placed upon the interior walls for a founda- 
tion, and the whole to be faced with solid stone-work of about the same thick- 
ness as the contemplated riprap or broken stone wall. According to the original 
plan of the aqueduct, the water from the Potomac is conducted into a receiving 
reservoir formed by a dam across a stream called Powder Mill or Little Falls 
branch, about nine miles below the head of the conduit, whence it is conveyed 
about two miles further down to a distributing reservoir, divided into two equal 
sections, or basins, by an embankment designed chiefly for filtering purposes. 
It is thus always intermingled with the water from Powder Alill branch. The 
latter stream drains a considerable extent of country, and is subject to frequent 
and heavy freshets, which render its water unfit for immediate use. At times 
this stream is clear, wfliile the water of the Potomac is rendered impure, by reason 
of heavy rains, nearer its source. It is, therefore, important that the aqueduct 
should be so constructed as to afford an adequate supply of water from whichever 
of these sources may, for the time{ be most free from impurities, and to exclude 
that which may be unfit for use. For this purpose, the engineer in charge pro- 
poses to connect the conduit above the receiving reservoir with that below it, so 
that the water from the Potomac may be brought directly into the distributing 
reservoir without being adulterated by that of Powder Mill branch. lie also 
proposes to construct a gate-house in the dividing wall of the distributing reser- 
voir, so as to admit of the use of the water from either section, as may become 
desirable. By means of these improvements, the requisite supply of water may 
be drawn from whichever of four distinct sources may be the purest and best, 
viz : the Potomac river, Powder Af ill branch, or either section of the distributing 
reservoir; but without some such arrangement, ' an unfailing and abundant sup- 
ply of good and wholesome water' cannot at all times be obtained. Under these 
circumstances, I have deemed it necessary to order these changes in the origi- 
nal plan, and have made the estimates of appropriations for the completion of 
the work to conform thereto. For information in detail in reference to this sub- 
ject I invite attention to the full and able report of the chief engineer. 
" Certain parties having, from time to time, made claim to heavy damages for 
the diversion of the water from the Potomac river, my immediate predecessor, 
with a view to settle and end this claim, entered into an agreement of arbitration 
with the claimants. Pursuant to this agreement, the arbitrators met from time 
to time, and finally submitted their award, by which they adjudged in favor of 
the claimants upon each and all of the plans and modes submitted to them, 
being three in number, for the construction of the dam across the Potomac, and 
also $12,000 for their own fees as arbitrators, and $761 84 for the expenses of 
arbitration. The sums being so large, I did not feel justified in applying the 
existing appropriation for the completion of the aqueduct to the payment thereof, 
preferring to submit the whole matter to Congress for its determination. It 
appears from the report of the experienced engineer in charge of the work, as 
must be obvious to every observer, that an ample supply of water for the use of 
the cities of Washington and Georgetown, for many years to come, can be ob- 
tained from the Potomac by the erection of a tight dam, extending from the 
Maryland shore to Conn's island, to a height which will give a head of six feet 
of water in the aqueduct, and yield a daily supply of about 65,000,000 gallons, 
which is thirty-three and one-third per cent, more than was used in the city of 
New York in the year 1861, when its population was over 800,000. In view 
of this fact, I have instructed the engineer to construct a dam of cut stone, with G 
WASHINGTON AQUEDUCT. 
a base sufficient to bear a superstructure of the required height for the full 
capacity of the aqueduct, whenever it may be called into requisition. 
" It is difficult to conceive how a dam of this character c in work any injury to 
the proprietors of the water right claimed at the Great Falls. At the utmost, it 
could only raise the water to a level at the head of the island, while at ordinary 
stages and at low water (the only time when any value can properly be placed 
upon the right) it would not increase or diminish the flow of water in the main 
channel on the west side of the island; and it surely cannot be pretended that 
the parties claiming the water right can lawfully divert the ordinary flow of the 
water on the east side of the island. A dam of the east channel that would 
raise the water to a height sufficient to fill the aqueduct would be a great ad- 
vantage to the claimants, for the reason that it would enable them to avail them- 
selves of the power by the erection of but one dam, while one that wotdd only 
back the water to the head of the island must be a matter of total indifference 
to them; because, in the very nature of things, it can work them no detriment 
whatever. 
" If this view shall be taken of the case by Congress, I recommend that a 
reasonable sum be appropriated to pay the expenses of the arbitration, and that 
the estimate of the cost of the dam across the main channel be diminished to 
the estimated cost of the dam over the east channel, thus leaving the greater 
expense of the dam to be provided for as the exigencies of the cities of Wash- 
ington and Georgetown, by the increase of their population, may require." 
Extract from, the last annual report of the chief engineer of the Wash- 
ington aqueduct. 
" The original estimate of the cost of this work, as submitted to 
Congress by the President, February 21, 1853, was 
" The above estimate being for a seven-feet conduit, and the plan 
having been afterwards changed to a nine-feet conduit, the 
engineer in charge, in his annual report for the year ending 
September 30, 1856, adds for additional cost of nine-feet 
conduit 
$1,921,244 00 
350, 000 
00 
2, 271, 244 
00 
" Or, in round numbers". - , 
2, 300, 000 
00 
" It appears, from the foregoing financial statement, that there 
had been expended, under the supervision of the War De- 
partment, up to June 18, 1862, the date of transfer 
"The engineer's 'report of operations on the aqueduct during 
the year ending September 30, 1862,' gives the amount ex- 
pended from June 17 to September 30, 1862 
$2, 675, 832 
53 
9,215 
80 
" Also the estimated cost of completing the aqueduct 
220, 008 
00 
" Making a total cost of 
2, 905, 056 
33 
" Or an increase over the original estimate, of 
605, 056 
33 
COST OF COMPLETION 
" The present estimate of the cost of completing the aqueduct will be found to 
embrace several items which have not appeared in former estimates, as well as 
a considerable increase in the cost of some of the original items, all of which 
produce a material increase in the aggregate cost of the work, and should be 
fully explained here. 
"The original estimate of the cost of the dam at Great Falls, and the work WASHINGTON AQUEDUCT. 
7 
connecting it with the Maryland shore, was $50,043., The plan upon which 
this estimate was based may be understood by the following extracts from the 
specifications: 
" ' The dam will be an embankment of rubble stone, with a top width of twenty 
feet; a slope on the upper side of one to one, and on the lower side of five to 
one. It will be made of large stones, the spaces filled with smaller ones, so as 
to form a compact mass; eight and a half feet from the upper slope, and laid 
parallel to it, there will be three feet in thickness of spalls and gravelling. Care 
will be taken to place on the outer surface of the bank stone sufficiently large 
to resist the action of high freshets.' 
" ' For thirty feet above the upper edge of the dam all materials will be re- 
moved for a depth of four feet below the level of the water in the pool, to form 
a boat channel that can be used in replacing any of the stones carried away by 
high freshets.' 
"This dam was located on a diagonal line, about three thousand feet in length, 
extending across the Maryland channel, the head of Falls island, the lower 
portion of Conn's island, and the main or Virginia channel, to a point on the 
Virginia shore about one-half of a mile above the feeder at the head of the 
aqueduct. 
" That portion across the head of Falls island, about six hundred feet in length, 
has been completed. 
" My own views as to the propriety of carrying out the above plan were sub- 
mitted to the department at considerable length in a communication dated Octo- 
ber 16, 1862. They have undergone no change,but have rather been confirmed 
by subsequent observation and experience. 
" The location seems to be a very unnatural one, and was evidently adopted 
from other than engineering considerations. I do not consider the structure a 
suitable one for a work of this kind, neither as regards stability nor impervious- 
ness. 
" In the communication above referred to it is recommended that the location 
of the dam be changed 'to the form of an arc, extending from the mouth of the 
aqueduct to a point on the Virginia shore below the mouth of the old canal, 
which happens to be almost directly opposite.' And it is also recommended 
that the plan be changed to 'a dam of the most substantial masonry.' 
"The Great Falls Manufacturing Company claim to be the owners of the right 
to use the whole or a large portion of the water flowing in the Potomac river in 
the vicinity of the Great Falls, by virtue of riparian rights acquired by them in 
the purchase of the adjacent shores and islands. This claim has always been 
resisted by the government. In the summer of 1858 a jury was summoned to 
assess the damages that would be sustained by this company by reason of the 
diversion of so much water as would be required to supply the aqueduct. Their 
verdict amounted to $150,000. An appeal was taken by the United States, by 
which the verdict was set aside. 
"On the 20th of November, 1862, an agreement was entered into between the 
Secretary of the Interior and the Great Falls Manufacturing Company, by which 
the whole question of damages was submitted to the arbitration and decision of 
five commissioners mutually agreed upon by the parties. 
" These commissioners made a personal examination of the locality in question ; 
and, after receiving a large amount of oral and written testimony on both sides 
of the case, made four alternative awards upon as many different plans and loca- 
tions for the proposed dam, which were submitted to them on the part of the 
government. As no action has since been taken by the Secretary of the Interior 
in relation to this matter, and as this item has not appeared in former estimates, 
the question of damages for land or diversion of water by reason of the con- 
struction of the dam will not be considered or provided for in the present 
estimate. 8 
WASHINGTON AQUEDUCT. 
''"As a question of engineering, however, I do not hesitate to recommend the 
adoption of the location and plan which contemplates the ultimate construction 
of a cut-stone dam of solid masonry entirely across the river, of sufficient height 
to secure a full and permanent supply of water for the aqueduct. Inasmuch, 
however, as many years may elapse before a supply equal to the full capacity 
of the aqueduct, or 85,000,000 gallons daily, will be required, the present esti- 
mate only provides for the construction of that portion of the dam extending 
from the Maryland shore to Conn's island, to a height which will give a head 
of six feet of water in the aqueduct, or a daily supply of about 65,000,000 
gallons. This dam will be so located and constructed as to admit of an addi- 
tional height of two feet, and an extension to the Virginia shore, whenever Con- 
gress shall think proper to make the necessary appropriation. 
" The theory upon which the works have been planned, and thus far con- 
structed, is as follows : The water drawn from the Potomac at Great Falls is to 
be conducted in the first instance through a circular conduit nine feet in diame- 
ter, a distance of about nine miles, and discharged into the receiving reservoir, 
(which contains about fifty acres of water surface,) and there allowed to inter- 
mingle with the water collected in the reservoir from the surface drainage of the 
surrounding country. It is then to be drawn through another nine-feet conduit, 
a distance of about two miles, to*the head of the distributing reservoir, near 
Drovers' Rest, which contains a water surface of about forty-two abres, and 
then either discharged into the distributing reservoir and drawn from thence for 
general distribution by means of large cast-iron mains, or carried past the dis- 
tributing reservoir through a seven-feet conduit which connects directly with 
the same cast-iron mains at the lower end of the reservoir. 
" It will be observed, that by this theory of working the aqueduct there can 
never be but one direct source of supply, to wit, the receiving reservoir; and 
but two qualities or degrees of purity to the water supplied, to wit, that which 
is drawn directly from the receiving reservoir, and that which is allowed a short 
time for rest or settlement in the distributing reservoir. The distributing reser- 
voir is divided into two sections, very nearly equal in size, by an embankment, 
the top of which was to be left two feet below the ordinary surface of the water 
in the reservoir, so that the water in the lower section would be drawn from the 
surface of the upper section. A culvert, with a stop-gate, was to be built through 
the bottom of the dividing bank for the purpose of draining the water from the 
upper section into the lower one, and from thence through a waste-pipe in the 
effluent gate-house, whenever it should be necessary for purposes of cleaning 
or repair. 
" The experience of the last four years has shown that the water collected in 
the receiving reservoir from the drainage of the surrounding country (and which 
has thus far been the only source of supply) is, during a great portion of each 
year, so muddy and full of sediment that it is often considered unfit for ordinary 
uses. It has also been observed that very often, when the water in the reser- 
voir is in this impure state, the water in the Potomac is comparatively clear and 
pure; and vice versa. These differences are occasioned by showers or heavy 
rains falling in the localities adjacent to the respective streams or sources of sup- 
ply, and are, of course, unavoidable. 
"It has, therefore, been deemed both advisable and important that every avail- 
able means should be adopted in the arrangement and working of the aqueduct, 
by which the water would be rendered as clear and pure as possible. With this 
object in view, it is recommended that the conduit above the receiving reservoir 
be connected with the conduit below the reservoir, so that the Potomac water 
may be brought directly into the distributing reservoir without adulteration wi-th 
the waters collected from other sources in the receiving reservoir. It is also 
recommended that the dividing bank in the distributing reservoir be built to the 
full height of the outside banks, so as to separate the water in the different sec- 
tions; and that, instead of the proposed culvert, a gate-house be so constructed WASHINGTON AQUEDUCT. 
9 
in this division bank that, in connexion with the effluent gate-house, the water 
may be drawn at pleasure from either section; and also so arranged that the 
lower section may be supplied with water from the surface of the upper section. 
" By means of this improvement in the distributing reservoir, and the connect- 
ion of the conduit through the receiving reservoir, we shall always be able to 
select a supply of water from whichever of four separate and distinct sources 
may, for the time being, be the purest and best. To illustrate, suppose 
that, at any time, both sections of the distributing reservoir are full of good 
clear water, and that a sudden shower or heavy rain should cause the water 
either in the Potomac or receiving reservoir, or both, to be too muddy for imme- 
diate use. The water from above would then be shut off temporarily from the 
distributing reservoir, and the supply would be drawn from the upper section 
until it became exhausted; after which the draught would commence from the 
lower section, while the upper one would be replenished either from the Poto- 
mac or receiving reservoir-from either of which the water may also at any 
time be supplied directly to the distributing mains. 
"It is believed that by the adoption of these simple expedients, we shall at all 
times secure a supply of water of the greatest degree of purity attainable, un- 
less we resort to the expensive process of filtration, which is now being success- 
fully adopted on a large scale in some of the most important water works in 
Europe, and will, undoubtedly, soon be adopted to a great extent in this country. 
"The original plans and ' specifications for the completion of the distributing 
reservoir, near Drovers' Rest,' required that the interior slopes or water faces 
should be faced with broken stone in blocks not exceeding three inches nor less 
than one and a half inch cubes, to be spread evenly on the surfaces to a depth of 
eighteen inches. Believing that this plan would not afford the banks proper 
protection from the action of the water, and finding that my opinions were con- 
curred in by the most experienced engineers in the country, I took the respon- 
sibility, on the 18th of May last, while acting as consulting engineer of the 
aqueduct, of recommending the following amendment to the specification, which 
being approved by yourself, on the 30th of July, is now in force: 
"AMENDED SPECIFICATIONS FOR THE COMPLETION OF DISTRIBUTING RESERVOIR 
NEAR DROVER'S REST. 
"All interior slopes shall have a uniform inclination of two feet base to one 
foot vertical. They will be faced with small broken stone or clean hard gravel 
to an average depth or thickness of six inches. Upon this foundation will be 
laid a rubble slope wall averaging fifteen inches in thickness, and varying from 
twelve to eighteen inches, according to location and circumstances, at the dis- 
cretion of the engineer. The foundation of the slope wall will be one foot be- 
low the bottom of the reservoir. The stone will be laid at right angles to the 
slope, and will be sufficiently large to extend through the wall, and to resist the 
action of the water. The face of the wall to be well wedged and pointed, 
either with pinners and spalls, or with clean hard gravel, as the engineer may 
direct, so as to prevent the water from displacing any portion of the wall or the 
broken stone underneath. 
" The top of the wall will be connected with a pavement rounded over the up- 
per front angle, and extending across the top of the division bank, and five feet 
back on the top of the outside banks. The pavement to be from six to ten 
inches thick, as the engineer may direct, and composed of field or quarried stone, 
of good quality and uniform size, compactly laid on their ends, and well bedded 
to a uniform surface in broken stone or clean hard gravel. 
"The top of the banks, from the outer edge of the paving, will be finished 
with a slope of one in twenty, inclining from the reservoir, so as to shed the 
water into the surface drains prepared for that purpose." 
"Although this change will somewhat increase the present cost of the work, it 
is believed that it will result in a great saving of future expense. 10 
WASHINGTON AQUEDUCT. 
"It has also been thought advisable to construct eight shafts upon the top of 
the conduit for purposes of ventilation, in order to allow of the escape of impure 
air, and the passage of a current of pure air over the surface of the water in 
the conduit. 
"No allowance has been made in former estimates for the cost of fencing the 
reservoirs and conduits, and the government lands connected with the aqueduct. 
This item is included in the present estimate. 
"The following is now submitted as the estimated cost of completing the aque- 
duct in accordance with the foregoing recommendations, from and after October 
1, 1863: 
Potomac, dam of solid masonry from the Maryland shore to 
Conn's island $54, 000 00 
Temporary dam for procuring three feet head of water during 
construction of permanent dam 2, 000 00 
Completion of head of conduit and cut-stone masonry connected 
therewith 5,000 00 
Completion of tunnels 6, 550 00 
Completion of conduit 4,844 00 
Completion of bridges 31,751 00 
Completion of gate-houses 26,560 00 
Completion of earthwork and water facings in distributing reser- 
voir 87,720 00 
Completion of central gate-house in dividing bank of distributing 
reservoir 20,500 00 
Completion of high service reservoir 8, 900 00 
Connection of conduit through the receiving reservoir 99,200 00 
Ventilators to conduit 2, 800 00 
Fencing reservoirs, conduit, and government lands connected 
therewith 25,000 00 
Engineering, superintendence and repairs, for the ensuing two 
years 40, 000 00 
Land and law expenses 20,000 00 
Constructing common roads 3, 500 00 
438,325 00 
Add ten per cent, for contingencies 43,832 50 
Total amount 482,157 50 
Deduct balance on hand 80,773 88 
Appropriation required 401,383 62 
If we add to the above the estimated amount required to com- 
plete the Potomac dam to its full length and height, say- . 145, 050 00 
And the amount of former appropriations 2,900,000 00 
We shall then have 3,446,433 62 
Or, in round numbers 3, 500, 000 00 
Which amount will represent the total cost of this great national work when 
fully completed in the most permanent and substantial manner, and upon a plan 
which will make its full capacity available for all coming time. 
"This amount cannot be considered as extravagant when compared with the 
cost of supplying other cities with water by means of artificial works, as will 
be seen by an examination of the following valuable table of statistics of water 
supply for various cities throughout the United States, compiled by Mr. Samuel 
McElroy, an eminent civil and mechanical engineer of Brooklyn, New York: WASHINGTON AQUEDUCT. 
11 
1 
Richmond 
New York 
Philadelphia 
luouiie 
New Orleans 
< HC. 
h 
1 
•???! 
MH 
Baltimore 
Boston 
Buffalo 
1 
■ 
Locality. 
g!?|ii8i§s§88g§igS§S 
Cost of works. * 
His 
: i 88 
Hii 
: ; : i 
: W1 
Cost of water rights. 
i •: "; 
; :|: 
; i 2; 
1, 500, 000 
6, 000, 000 
4, 000, 000 
;;; £ 
;;;l 
: :: § 
Gallons. 
12, 000, 000 
18, 440, 000 
20, 000,000 
Daily supply controlled. 
wxwjfeSpm 
IIIIW 
§§§§§§§! 
3, 877, 910 
4, 618, 000 
710, 984 
2,142, 000 
785, 000 
2, 000, 000 
Hi 
OS 
Gallons. 
2, 500, 000 
Daily supply used, 1859. 
; ; £"i ; 
;; II;; 
: ; as: : 
ii 
4, 445, 000 
4,841, 520 
4, 855, 500 
881, 600 
■ ®.po."qi 
i *ll| 
Daily supply used, 1861. 
s; 
S: 
79,000 
26,000 
18,000 
§1 
35,000 
51,000 
8,623 
13, 097 
7, 771 
18,000 
SS; 
i 
Annual expenses, 1859. 
146, 140 
159, 835 
j ■ 
mg 
• 
Annual expenses of ex- 
tensions, 1861. 
38,152 
79,154 
r; 
41, 748 
24, 823 
46, 446 
9, 406 
Annual expenses of ad- 
ministration, 1861. 
"i 
g; 
•>•>, uuu 
140, 000 
759, 250 
551,000 
69, 000 
32, 000 
f: 
Hi. 
s 
Annual receipts, 1859. 
765, 954 
533, 980 
s; 
&; 
: St 
: 
Annual receipts, 1861. 
280. 25 
337 
8: 
137 
95.3 
85 
24.38 
: a w 
Miles of distribution. 
8sssg?ss$sgassS|s5Ea 
gaoims£B§ms§2$£ 
• 
Population, 1860. 
* r * 
Power. 
Power. 
Population, 1860. 
* In part. t Assessed. J Supply just introduced. § About. 
Miles of distribution. 
Annual receipts, 1861. 
Statistics of water supply, compiled from various authorities. 
Annual receipts, 1859. 
Annual expenses of ad- 
ministration, 1861. 
Annual expenses of ex- 
tensions, 1861. 
Annual expenses, 1859. 
Daily supply used, 1861. 
Daily supply used, 1859. 
Daily supply controlled. 
Cost of water rights. 
Cost of works. 
Locality. 12 
WASHINGTON AQUEDUCT. 
"From this table it appears that, although the Washington aqueduct will 
furnish a supply of double the amount furnished by any of the water works 
named, its cost will be much below the average of those of even one-half the 
capacity. 
"The original estimate of the cost of the Washington aqueduct.was made in 
1853, or ten years since, and at a favorable time for the accomplishment of such 
a work. There is no reason to doubt that the estimate was ample for the com- 
pletion of the work upon the plans then proposed, provided the appropriations 
had been made by Congress, so as to have allowed of the uninterrupted prose- 
cution of the work to completion. 
"The excess of the estimate of October 1, 1862, over the original one, (to wit, 
$605,056 33,) may be accounted for in a great measure by the unavoidable con- 
sequences growing out of the periodical delays and suspensions of the work for 
the want of funds; such, for instance, as deterioration and waste of materials, 
tools, machinery, and fixtures ; extra allowances to old contractors for damages, 
and extra prices to new ones for the completion of old and unfinished work; 
cost of engineering, superintendence, office expenses, repairs, &c., &c.; all which 
must necessarily amount to a very large per-centage on the final cost of the 
work. 
" When to this is added the extra cost of the additions and improvements 
recommended in this report, and provided for in the present estimate, the dis- 
crepancy of $1,146,433 62 between the present and original estimates cannot 
be regarded either as unexpected or unreasonable in a work of this character 
and magnitude." 
In submitting further explanations, and stating additional reasons for the 
changes already adopted, and those recommended in the foregoing and present 
reports, reference will first be made to the change in the location and character 
of the dam in the Potomac river above the Great Falls, which is designed to 
turn the Potomac water into the aqueduct. the annexed map.) In this 
connexion I desire respectfully to refer to the annexed "Report of S. Seymour 
to the Hon. John P. Usher, Assistant Secretary of the Interior, in relation to 
the proposed dam at the Great Falls of the Potomac," dated October 16, 1862.* 
Reference is also made to the annexed extracts from the testimony of Messrs. 
James Slade, of Boston, Massachusetts, Samuel McElroy, of Brooklyn, New 
York, and Marvin Porter, of Davenport, Iowa, civil engineers of ability and 
experience, upon the same subject, taken in December, 1862, and January and 
February, 1863, before the commissioners appointed to examine and decide the 
question of damages sustained by the Great Falls Manufacturing Company, by 
reason of the diversion of a portion of the water from the Potomac to supply 
the aqueduct; also to that of John G. Stone, a former superintendent upon 
the Chesapeake and Ohio canal, f 
It is respectfully submitted that it is unnecessary to add anything more upon 
this subject in order to justify the change in the plan and location of the dam 
at Great Falls, from an "embankment of rubble stone," as designed and was 
being constructed by Captain Meigs, to a dam of solid masonry, as adopted by 
the Secretary of the Interior. 
The amount expended, up to the 1st instant, on the permanent dam, is 
$3,700. And it is estimated that a further amount of $49,000 will be required 
to complete the dam from the Maryland shore to Conn's island, to a height 
which will give a head of from five to six feet of water in the aqueduct, and a 
daily supply of from fifty to sixty million gallons of water. 
Another change in the original plans is recommended by the Secretary of the 
* See Appendix D, p. 2G. 
t See Appendix E, p. 30. Section of EuLbankment of Rutible Stone 
Section of Masonry Dam NOTEThis reservoir 
receives the dlinn o'J'\ of 
about AO 00Acres of nbe 
surroun dma CouMtrv 
WASHINGTON AQ U EDU CT .1 
MAP OF 
T HE 
KE C EJVIN G RE SERVO 1R. 
TO ACCOMPANY SUPPLEMENTAL REPORT OF 
C HIE FEN G1XE E R . 
Dated Eeb.22ud 1864. 
Bowen &Co litli.Pliilada. WASHINGTON AQUEDUCT. 
13 
Interior, and provided for in the estimates of the chief engineer, to wit: the 
extension of the conduit from a point above tunnel No. 4, around the lower por- 
tion of the receiving reservoir, to the effluent gate-house, so as to enable the 
water from the Potom ic river to be brought in its pure state into the distribu- 
ting eservoir, without adulteration with the waters collected in the receiving 
reservoir, from the surface drainage of about four thousand acres of the surround- 
ing country. (See the annexed map of the receiving reservoir.) In addition 
to the reasons given for this change, in the foregoing extracts from the reports 
of the Secretary of the Interior and the chief engineer of the aqueduct, I have 
to state that since the introduction of the Potomac water into the receiving reser- 
voir, December 5, 1863, the water supplied to the city from the receiving reser- 
voir has been unusually impure and muddy, although the weather has not been 
unusually rainy; whereas, previous to that time, the water in this reservoir, 
during intervals of dry weather, would be reasonably clear. I can account for this 
circumstance in no other way than from the fact that it has been necessary, 
since the introduction of the Potomac water, to keep the water surface in the 
reservoir from two to seven feet lower than before, in order to allow the Poto- 
mac water to flow into it; thus affording the winds and waves, and also the 
strong current, discharged from the upper conduit, an opportunity to stir up the 
sediment which has been for some years accumulating upon the immense shore- 
line which surrounds it, as well as upon the uneven and, in many places, shal- 
low surface of the bottom. It will be remembered that the elevation of the 
present dam at Great Falls, and the bottom of the waste-way of the reservoir, 
are the same, to wit, 145 feet above datum line of the aqueduct, or the level of 
mean tide in the Potomac, so that, if the water*in the reservoir is kept at or 
above that elevation, no water, except at high stages, can flow into it from the 
Potomac. And, in order to obtain any considerable quantity of water from the 
Potomac with the present height of the dam, the surface of the reservoir must 
be kept, at least, from two to three feet below the bottom of the waste-passage; 
whereas, during several months previous to the introduction of the Potomac 
water, it bad been kept from three to five feet above that level, by means of a 
temporary dam across the passage. These considerations incline me very 
strongly to the opinion that it will be necessary to shut the Potomac water en- 
tirely off from the reservoir, and to raise the water in the reservoir to its pre- 
vious height until the Potomac dam can be completed, and a connection made 
between the conduit above and the conduit below the reservoir. In view of 
this contingency it is quite as important that the proposed connection in the con- 
duit be made, as it was in the first instance that the works should be completed 
from the Potomac, at Great Falls, to the receiving reservoir. \ 
1 he experience thus far, with reference to this reservoir, certainly goes very 
far towards proving the fallacy of Captain Meigs's theory with reference to it, 
as stated in Ex. Doc. No. 82, II. 11., 34th Congress, 1st session, to wit: "The 
water enters this reservoir by a tunnel, at a distance of half a mile from the point 
at which it leaves it; and during its passage through this deep pool, time is af- 
forded for it to deposit most of its impurities." 
As an illustration of the comparative degree of purity of the water in the Po- 
tomac, and the water as it is drawn from the receiving reservoir, I procured sam- 
ples ot each on the 20tli instant, which show a very marked difference in favor 
of the 1otomac water, lhe, weather had been clear and cold during several 
weeks preceding that date, and the surface of the reservoir was frozen at the 
time to a depth of several inches. T he water at the mouth of the upper conduit 
appeared quite clear; but the shade, as it approached the effluent gate-house, 
grew visibly darker and more turbid. 
No expenditure has been made on account of this proposed change ; but an 
item providing tor its cost will be found in the annual report, amountin0, to 
$99,200. ° 14 
WASHINGTON AQUEDUCT. 
Another change has been in part adopted, and is now, to some extent, being 
carried out, with reference to the distributing reservoir near "Drovers' Rest," to 
wit: First, in the substitution of slope wall for riprap facing on the interior 
slopes, and extending the same from the bottom of the reservoir to and over the 
top of the slopes. Second, in the construction of the dividing bank to the full 
height of the exterior banks, and the substitution therein of a central gate-house, 
for the culvert, as heretofore contemplated. Third, in the excavation of the 
whole, or a portion of the bottom of the reservoir, to an additional depth of thir- 
teen feet. (See the annexed plan of the distributing reservoir.) With reference 
to the first change, I beg leave, in addition to the reasons assigned in the fore- 
going extracts from the reports of the Secretary and chief engineer, to refer to 
the annexed communication, addressed on the 18th May, 1863, to the Secretary 
of the Interior, while I was acting as consulting engineer of the aqueduct, and 
containing a correspondence upon the subject with Messrs. James P. Kirkwood 
and Alfred W. Craven, of New York, and James Slade, of Boston, all of whom 
hold positions in the first rank of American engineers in connection with works 
of this kind.* 
It is proper to state that the change in the plan of finish for the water facings 
involves not only the character of the walls, but also the extent of surface to be 
covered by them ; and that the increase of cost is not so much on account of the 
quality, as the additional quantity of work proposed to be done. The original 
plan contemplated that the slopes should be covered with broken stone, or rip- 
rap, eighteen inches thick only, from a point one foot above the surface at the 
flow-line, to a point seven feet below the surface, making a vertical height of 
eight feet-thus leaving the itpper angle and slope of the banks, and also that 
portion of the slope below the foot of the riprap, (which will frequently be left 
bare by the drawing down of the water,) exposed to the action of frost and the 
waves. The aggregate increase in the cost chargeable to this change in the plan 
is estimated at 832,308, of which 823,888 is chargeable to the additional quantity 
required to cover the entire slopes, and $8,420 to the change in the character of 
the work from riprap to slope wall. There has been expended up to the 1st 
instant, on the slope walls built according to the present plan, $11,525; and the 
amount required to complete them is estimated at $49,375. 
The reasons for the change in the elevation of the dividing bank, and the 
substitution therein of a gate-house for the culvert, are fully stated in the fore- 
going extracts from the annual reports of the Secretary and chief engineer. The 
design is to secure additional purity to the water at a very small comparative 
expense. Nothing has been expended on account of this proposed change ex- 
cepting the purchase .of some bricks for the small conduit leading from the cen- 
tral to the effluent gate-house, which can be used for other purposes if the im- 
provement be abandoned. The additional cost of this improvement, including a 
slight change in the effluent gate-house to admit of the water being drawn with 
greater facility from the surface, at different elevations, is estimated at twenty- 
three thousand nine hundred dollars. 
The change proposed in the elevation of the bottom of the distributing res- 
ervoir is not referred to in either the annual report of the Secretary or chief en- 
gineer, and will therefore be fully explained here. 
The level of the bottom of the reservoir, as established by Captain Meigs, 
and as now being graded, is two feet above the bottom of the conduit, which 
discharges into it at the influent gate-house, and fifteen feet above the centre 
of the discharge-pipes or mains which lead from it at the effluent gate-house; 
and it is only eleven feet (or ten feet as shown in the plan of Captain Meigs) 
below the flow-line or surface of high water in the reservoir-making the capacity 
of the reservoir, which contains an area of forty-four acres of water sur- 
° See Appendix F, p. 37. DISTRIBUTING | RESERVOIR 
(a pa ci tv at depth of // feet HOSjf) Ot/()\ (iglhms. 
„ „ a 21 ,, \ L 
Secbmi of Bank as originally designee / MzM 
partial rip rap f acini]. 
Section ot Bunk with Slope l\ult fadrvq 
anil propost it increase of ilepth. 
WASHINGTON AQUEDUCT. 
I'LAX OF 
DISTRIBUTING RESERVOIR 
TO ACCOMPANY SUPPLE MENTAL HEPORTOF' 
CHI F F E NCI N E E R . 
Dated Feb. 22nd 186 4. 
Sechonof Bank with rip rap facing on euhre 
slope ■ WASHINGTON AQUEDUCT. 
15 
face, equal only to one hundred and fifty million eight hundred and fifty thou- 
sand gallons ; whereas, if the bottom was excavated to the lowest depth at 
which water can be drawn through the discharge-pipes, we should have a depth 
of twenty-four feet of water and a capacity of two hundred and ninety-nine 
million nine hundred thousand gallons, or double the amount of its present ca- 
pacity. 
The additional cost of this improvement is estimated at two hundred and 
twenty-three thousand one hundred dollars. I have been unable to find in the 
reports on file in this office any reasons given for the adoption of the present 
level for the bottom of the reservoir, and therefore suppose it to have been done 
merely for purposes of economy. The advantages of the proposed change ap- 
pear to be obv'ous, and may be briefly stated as follows: First. Double storage 
capacity in the reservoir; and second, greater purity as well as coolness in the 
water, on account of its additional depth. I am so thoroughly impressed with 
the importance of adopting every available expedient within the limits of rea- 
sonable economy which will be calculated to improve the purity of the water, 
that, in case Congress should make an adequate appropriation, Iwould recom- 
mend that at least one section of the reservoir should now be excavated to the 
full depth, even if it involved the entire suspension of work upon the remaining 
section until Congress should feel justified in providing for its completion in the 
same manner. In that case, the storage capacity of this completed section 
would be substantially the same as that of the entire reservoir when completed 
upon the present plan, and the quality of the water would be greatly improved. 
The same object, however, would be more thoroughly accomplished by com- 
pleting the upper section (the water facings of which are now far advanced) 
to a depth of eleven feet, and the lower section (upon which the slope wall has 
not been commenced) to the full depth of twenty-four feet. 
The estimated cost and storage capacity of each section, when completed to 
different depths below the flow line, will be found in a subsequent part of this 
report. 
An additional reason for carrying out this improvement at the present time 
is, that in all probability the use of the receiving reservoir for storage and puri- 
fying purposes will have to be abandoned for the reasons hereinbefore stated; 
and, in that event, the full capacity of the distributing reservoir for both pur- 
poses should be brought into immediate requisition. Experience will also pro- 
bably demonstrate the inability of the conduit above the reservoir to sustain 
the pressure of any considerable head above the crown of the arch; in which 
case, the water in the reservoir must be kept at an elevation which will give 
only seven feet depth above the present bottom, and a capacity of only ninety- 
four million five hundred thousand gallons. 
I beg leave, in this connection, to call your attention to the annexed "Paper 
in relation to the receiving and distributing reservoirs, prepared by Mr. J. J. R.- 
Croes, principal assistant engineer," which will be found to contain many details 
and much v aluable information not embraced in this report. * 
With reference to the items of ventilating shafts upon the top of the conduit, 
and the fencing of the reservoirs, conduit, and government lands connected with 
the aqueduct, which have not been included in former estimates, I have nothing 
additional to say. 
The above, I believe, embraces all the material changes in and additions to 
"the plans and estimates of Captain Meigs," together with the information ahd 
explanations relating thereto, to which you will desire to call the attention of the 
committee. 
I desire to add, in this connection, that the plans designed by Captain Meigs 
for the aqueduct, were probably the best that could be devised at the time, from 
* See Appendix G, p. 39. 16 
WASHINGTON AQUEDUCT. 
the lights and experiences then available for reference. The changes since 
adopted, and now recommended, should, in the language of the annual report, be 
regarded " as only the natural results of experience and observation on this and 
other works of a similar character during a period of ten years which has elapsed 
since the commencement of the work; and should, therefore, not be regarded 
as reflecting any discredit upon the plans as originally adopted." 
The history of this work would differ materially from that of any other pub- 
lic improvement in the country, if the experience and observation of each suc- 
ceeding year of its construction and use did not develop the expediency of some 
changes in the original plans and estimates, which, if adopted, would prove ad- 
vantageous to the work. It seems, therefore, but just to assume that Congress 
will indorse these improvements, when convinced of their utility; and that it 
will hold any person in whose charge the work may be placed responsible for 
their incorporation in the plans and estimates, so that this great national work, 
when fully completed, will not be inferior in any respect to those of a similar 
character in this or any other country. 
The other items in the estimate, it is supposed, are sufficiently explained in the 
engineer's annual report. They are for the completion of unfinished mechanical 
structures, in order to render them more useful, and to protect them from injury 
on account of exposure to the elements. 
It may be proper, however, to remark, with reference to the "high-service 
reservoir," in Georgetown, which stands apart from the main line of works, that 
I find in the report of Captain Meigs, dated February 12, 1853, (see32d Congress, 
2d session, Ex. Doc. No. 48, page 23,) the following allusion to it: "A portion 
of Georgetown is at too great a height to be supplied by the natural flow of 
water from any source within reach. I propose for this high service-supplying, 
perhaps, a thousand people-to pump water into a reservoir upon the heights of 
Georgetown. This reservoir will be of earth, the materials of the bank being 
supplied by the excavation in the centre. It will be about three-fourths of an 
acre in extent, and contain, when filled to a depth of 10 feet, about 2,500,000 
gallons. The pump will be worked by a small turbine, placed near the river 
in Georgetown; and driven by a pipe from the main, with a head of 162 feet. 
The difference of level to be overcome being only 48 feet, the expenditure of a 
small quantity from the main will suffice to keep the reservoir full. The wheel 
and pump will be of sufficient power to raise the quantity needed for the daily 
consumption in ten hours, so that the water necessary may be drawn from the 
mains at those hours of the night or day when it can be best spared." The es- 
timated cost (see page 49 of same report,) was $18,928. 
It appears that the plan was subsequently changed, as the present elevation 
is 80 feet above the flow-line of the distributing reservoir, and the capacity is 
only 1,880,000 gallons. A Worthington pump has also been substituted for the 
proposed turbine. The expenditure on account of this work, as nearly as can 
be ascertained, has been $40,000, exclusive of land. The roof is yet to be com- 
pleted, and some leakages, which have prevented its successful use up to the 
present time, have to be tepaired. The estimated cost of all which is $8,920. 
A statement of the "mains laid by the United States" in connection with the 
Washington aqueduct, will be found appended to this report. * 
It is estimated that from eight to ten million gallons of water have been dis- 
tributed daily during the past two years, and that nearly double that quantity, 
or say fifteen million gallons, will be required during the next two years; this is 
more than can be relied upon, with any degree of certainty, in the present con- 
dition of our works at Great Falls. 
The question of damages to the Great Falls Manufacturing Company by reason 
of the construction of the dam, and the diversion of a portion of the water from 
° See Appendix H, page 48. WASHINGTON AQUEDUCT. 
17 
the Potomac river, will, undoubtedly, receive a thorough examination by the 
committee ; and it is to be hoped that their investigations will lead to a final 
settlement of this long-pending and vexatious question. The present status of 
the case is stated in the Secretary's report, and in the annual report of the chief 
engineer. The agreement for submission to arbitrators, the testimony taken in 
the case, the award of the commissioners, together with a map of the premises 
showing the alternative plans and locations of the dam, have all been placed in 
the hands of the committee. 
Although the present estimates do not contemplate the immediate construc- 
tion of the dam entirely across the river, yet it is to be hoped that Congress 
will see the propriety, as well as economy, of providing the right of way for the 
whole distance, so that no further controversy can ever arise in relation to the 
matter. 
A map of the entire line of the aqueduct is attached to this report, which will 
show the relation of all the changes, herein discussed, to the whole work, and 
also the location of the government mains in the cities of Georgetown and 
Washington. 
With reference to the question of " the necessity for further appropriations " 
for the protection and prosecution of the work, I have to say that, in the present 
disturbed condition of the country, and the consequent heavy draught upon its 
resources, it is not to be expected that Congress will make any further appro- 
priations than may be necessary for the proper safety and protection of the work 
already done, and the completion of such portions as will secure to the depart- 
ments of government, and the inhabitants of the cities of Georgetown and 
Washington, (who have now become entirely dependent upon this means of 
supply,) the requisite quantity of the purest and healthiest water attainable by 
the expenditure of a reasonable amount of money. 
The amount of the present appropriation unexpended at the beginning of the 
present month does not exceed $18,000. This will not be sufficient for purposes 
of ordinary repairs during the next fiscal year. The work of completing the 
distributing reservoir is now progressing slowly; but it should be suspended at 
once unless a further appropriation be made immediately. 
The following is a summary of all the items, with their cost, embraced in the 
present estimates for the completion of the work: 
3. Necessity for further appropriations. 
1. For the completion of the Potomac dam to Conn's island, to a 
height giving from five to six feet head of water in the conduit. 
$49, 000 
2. Completion of masonry at the feeder and head of conduit 
1, 485 
3. Completion of gate-house at Great Falls .■ 
3, 480 
4. Trimming, plastering, arching, and lining in tunnels that 
appear defective 
5, 125 
5. Completing the paving, coping, and railing of stone arch bridges, 
to prevent injury from exposure 
27,565 
6. Repairs to roof of effluent gate-house at the receiving reservoir, 
400 
7. Completion of influent and auxiliary gate-houses, and pipe 
vault, at the distributing reservoir 
9,240 
S Completion of high-service reservoir in Georgetown 
8,920 
9. Connecting the conduit above with the conduit below the 
receiving reservoir 
99, 200 
10. Completing tlie distributing reservoir to the full depth of twenty- 
four feet, with slope-wall facings, including the effluent and 
central gate-houses, with connecting conduit complete, giving a 
storage capacity of 299,900,000 gallons 
332,970 
11. Constructing ventilators upon the conduit 
2, 800 
Mis. Doc. 83 2 18 
WASHINGTON AQUEDUCT. 
12. Fencing conduit, reservoirs, and government lands connected 
therewith 20,000 
13. Engineering, superintendence, and repairs for the ensuing two 
years 35, 000 
14. Land and law expenses 10, 000 
605, 185 
15. Add ten per cent, for contingencies 60, 518 
Total amount 665, 703 
Deduct balance on hand 1st February, 1864 18, 000 
Appropriation required to complete 647, 703 
Note.-The increase of appropriation required by the present, over 
the estimate contained in the annual report, is accounted for by 
the additional cost of completing the distributing reservoir to the 
depth of twenty-four instead of eleven feet, which amounts, with 
ten per cent, added, to 245, 410 
By deducting which will leave a balance of 402, 293 
It will be observed that no provision is made in the above estimate for the 
settlement of the land question at Great Falls, nor for the completion of the 
Potomac dam to its full height entirely across the river. 
The following additional summary is given of the cost (exclusive of ten per 
cent, for contingencies) of completing certain portions of the distributing reser- 
voir in the manner specified : 
16. For completing the whole reservoir to a depth of eleven feet, 
including the central gate-house, the conduit connecting it 
with the effluent gate-house, and the raising of the dividing 
bank to its full height, giving a storage capacity of 150,850,000 
gallons $109, 870 
17. For completing the upper division to a depth of eleven feet, in- 
cluding a coffer-dam around the site of the central gate-house, 
so as to admit of its future construction, and the raising of the 
dividing bank to its full height, giving a storage capacity of 
86,120,800 gallons 41,800 
18. For completing the upper division to a depth of twenty-four feet, 
including the central gate-house, connecting conduit, and 
dividing bank, as in item 16, giving a storage capacity of 
172,530,000 gallons 163,854 
19. For completing the lower division to a depth of twenty-four feet, 
including a coffer-dam, and the raising of the dividing bank, 
as in item 17, giving a storage capacity of 127,370,000. 171, 700 
20. For completing the upper division to a depth of eleven feet, and 
the lower division to a depth of twenty-four feet, including 
the central gate-house, connecting conduit, and dividing bank, 
as in item 16, giving a storage capacity of 213,500,000 
gallons 230, 436 
If Congress shall concur in the opinion that any further appropriations should 
be expended with a view only of improving the quality of the water, so far as 
it can be done, by drawing a full supply directly from the Potomac, without 
adulteration with the water collected from other sources in the receiving reser- 
voir, this result can only be accomplished by the completion of the Potomac WASHINGTON AQUEDUCT. 
19 
dam to Conn's island and the construction of the connecting conduit around the 
lower end of the receiving reservoir. 
If, in addition to this, it shall be thought advisable to bring into use, for stor- 
age and purifying purposes, the cheapest and most available portion of the dis- 
tributing reservoir, this object will be attained by the completion of the upper 
or western division of the reservoir to its present depth of eleven feet. In doing 
this, however, provision should be made for the completion of the influent and 
auxiliary gate-liouses and pipe-vault connected with the distributing reservoir. 
If, in addition to the foregoing, it shall be thought proper to repair and com- 
plete the high-service reservoir at Georgetown, which is very much needed, and 
also to provide an adequate amount for engineering, repairs, and contingencies, 
the items, as numbered above, making up the appropriation, will be aggregated 
as follows : 
1. For Potomac dam $49,000 
9. For new conduit around the receiving reservoir 99, 200 
17. For completing upper section of the distributing reservoir to a 
depth of eleven feet 41, 800 
7. For completing influent and auxiliary gate-houses and pipe- 
vault at the distributing reservoir 9, 240 
8. For completing high-service reservoir at Georgetown 8, 920 
13. For engineering, superintendence, and repairs, say 20, 000 
228, 160 
15. Add ten per cent, for contingencies 22, 816 
Total amount 250, 976 
Deduct balance on hand 1st Feb., 1*864. . 18, 000 
Appropriation required 232,976 
4. Sewerage in the city of Washington 
The subject of "sewerage in the city of Washington," also embraced in the 
Senate resolution, wdl be found referred to in the following extracts from the 
annual reports of the Secretary of the Interior and of the chief engineer of the 
Washington aqueduct : 
Extract from the report of the Secretary of the Interior. 
" The report of the engineer will not fail to arrest the attention of Congress 
in another important particular. 
" The immense volume of water which the aqueduct will soon furnish will 
afford an ample supply for fountains at all appropriate places, and for cleansing 
the streets and sewers of the city-keeping them at all times in a healthful and 
agreeable condition. But in order to the accomplishment of this most desirable 
object, the present system of expenditure for the repairing of streets and the 
construction of sewers must be abandoned, or modified to such an extent as to 
place it under one control. I can perceive no good reason why the government 
should take upon itself the exclusive management and repair of one or more of 
the streets and avenues of the city, while all are equally necessary to the con- 
venience and comfort of the citizens of the United States visiting or residing in 
the city of Washington. The great width of its numerous streets and avenues 
quite discourages any attempt to completely pave them ; nor is it desirable that 
it should be generally done, when we consider the increased amount of heat 
that would be radiated from their exposed surfaces, and the clouds of dust that 
would be constantly sweeping over them. 
" It is believed that this may be avoided to a great extent by allowing, in 20 
WASHINGTON AQUEDUCT. 
some instances, the adjoining proprietors to extend the sidewalks into the streets, 
so as to reduce the latter to a proper width for pavement or concrete, and to afford 
space for grass plots in front of their dwellings, and in other streets by making 
a park of proper width through the middle for the cultivation of trees and 
plants and the erection of fountains. By the adoption of such a course the 
streets and avenues of the city would be reduced to such width as to admit of 
their being thoroughly paved at a reasonable cost, and the beauty and comfort 
of the city immensely increased. But neither this nor any other great improve- 
ment can be expected under the present law. They should be so modified as 
to require a uniform and perfect system of sewerage throughout the city, and to 
superintend this, and to improve and repair the streets, commissioners should 
be provided, one to be appointed by the government, and one or more by the 
corporate authorities of the city-the money appropriated by Congress to be 
expended in such proportion to the sum provided by the city as should be pre- 
scribed by law, and the obligation imposed upon the city to raise by taxation, 
annually, such sum as might be deemed by the commissioners necessary for the 
objects to be accomplished." 
Extract from the report of the chief engineer. 
" The introduction, by artificial means, of a large supply of water into towns 
and cities for the use and comfort of the inhabitants must, as a matter of course, 
create a necessity for a revolution in the system of drainage and sewerage pre- 
viously in use; and on that account, as well as on account of the intimate rela- 
tions which naturally exist between the two improvements, they are generally 
placed under the same general direction and superintendence. This has not 
been the case in the present instance. The drainage facilities for the cities of 
Georgetown and Washington are. at present, only intended to accommodate the 
discharge of water falling on the* surface which is naturally tributary to this 
drainage, together with the sewage of the cities; and they are found in many 
instances to be much too limited for even these purposes. 
" The introduction, by means of the aqueduct, of from twenty to fifty million 
additional gallons of water daily into these cities, and the necessary discharge 
of a large portion of it into the drains and sewers now in use, will at ouce create 
a necessity for an entire remodelling of the present system of drainage upon a 
much larger and more extensive scale. This may not be so important in George- 
town, on account of the greater irregularity of the surface and declivity of the 
streets, as in the city of Washington, where the ground is more level, and the 
drainage more sluggish. 
" At the present time a very large portion of the drainage and sewerage of 
Washington is discharged into a shallow, open sewer, of about one hundred 
and fifty feet in width, (sometimes called a canal,) which stretches its filthy 
surface through the heart of the city, and within a stone's throw of the Capitol 
of the United States, the President's House, the Treasury Department, and all 
the principal hotels on Pennsylvania avenue, breeding disease and pestilence 
along its borders. The accumulated filth and excrement of the city is con- 
stantly. held in a state of semi-solution in this hotbed of putrefaction, by means 
of the ebb and flow of the tides, over a surface of more than a million square 
feet. And whatever portion of it ultimately finds its way into the Potomac 
river is spread out in thinner proportions over several hundred acres of flats 
immediately in front of the city, the surface of which is exposed to the action 
of the sun at intervals during the day, and the miasma from which contaminates 
every breath of air which passes, from that direction, through or over the city. 
" All this may be remedied by the adoption of the most simple and natural 
expedients. A portion of the canal, say twenty or twenty-five feet in width, 
should be walled in and arched over, and a flood-gate inserted at its junction 
DRAINAGE AND SEWERAGE." WASHINGTON AQUEDUCT. 
21 
with the river; this portion should be used exclusively for purposes of sewerage 
and drainage, while the remaining longitudinal section should, by the adoption 
of a proper system of flood and stop gates and locks, be kept constantly filled, 
t > the level of high tide, with pure Potomac water. The water thus held in the 
canal, together with the water from Tiber creek and the surplus water from 
the aqueduct, should, when necessary, be allowed to flush through the main 
sewer at low tide, and thus keep it entirely free from sediment and deposit. By 
this arrangement open canal would not only be ornamental, but exceedingly 
useful for commercial purposes. 
" By the construction of a breakwater in the Potomac from the fo >t of Mason's 
island a few thousand feet down the stream, and so located as to divert the 
main current from the Virginia to the Maryland shore, and the removal of a 
portion of the north end of the solid causeway in the present Long bridge, at 
the foot of 14th street, so as to admit of a channel fifteen hundred or two 
thousand feet in width, the main channel of the Potomac would be brought 
immediately in front of the city of Washington, with a depth of water from 
twenty to thirty feet, into which the drainage from the main sewers of the city 
would be discharged and completely removed by the action of the current. 
"The commercial advantages resulting to the city from both, these improve- 
ments would be almost incalculable, while a fruitful cause of sickness and dis- 
comfort would be removed. The cost of the improvements would 
be comparatively moderate, and should be borne proportionately by the gov- 
ernment, the corporation of Washington, and the owners of the property which 
would be benefited by the improvements." 
Should Congress deem .it proper to refer the matter of sewerage and drainage 
to the Department of the Interior for examination, in connection with the 
Washington aqueduct, I should take pleasure in making a thorough examina- 
tion of the subject, and in presenting such plans and estimates for the same as, 
I should hope, would meet with the approval of the Secretary and of Congress. 
A joint resolution, looking to that object, has already been introduced into the 
Senate at its present session, and referred to the Committee on the District of 
Columbia. 
A bill has also been introduced in the House of Representatives, and referred 
to the same committee of the House, " To provide for the improvement of the 
Potomac river, opposite the city of Washington," which is a matter intimately 
connected with the sewerage of the city. As neither of these measures con- 
template any appropriations of money by Congress, it is to be hoped that they 
will receive early and favorable action. 
5. Want of a collection and proper arrangement of all laws and 
REPORTS RELATING TO THE WASHINGTON AQUEDUCT. 
I desire to say, in conclusion, that during my connection with the Washington 
aqueduct, and particularly while preparing this report, I have felt the want of 
a connected, synoptical arrangement of all the laws, reports, and other pub- 
lished and important matter connected with this work, from its first inception 
to the present time; and I have no doubt that the committee, as well as 
Congress, have felt, and will continue to feel, the same want. 
I would, therefore, respectfully, but earnestly, recommend that some provi- 
sion be made for the publication of all such matter in a convenient form for 
reference at an early day. 
All which is respectfully submitted. 
S. SEYMOUR, 
Chief Engineer of the Washington Aqueduct. 
To the Honorable 
John P. Usher, 
Secretary of the Interior. 22 
WASHINGTON AQUEDUCT. 
APPENDIX 
TO THE 
SUPPLEMENTAL REPORT OF THE CHIEF ENGINEER OF THE 
WASHINGTON AQUEDUCT, DATED FEBRUARY 22, 1864. 
PRESIDENT'S MESSAGE IN REFERENCE TO THE CONDITIONS ATTACHED 
TO THE APPROPRIATION PASSED JUNE 25, 1860. 
To the House of Representatives : 
I have approved and signed the bill entitled " An act making appropriation 
for sundry civil expenses of the government for the year ending the 30th June, 
1861." 
In notifying the House of my approval of this bill, I deem it proper, under 
the peculiar circumstances of the case, to make a few explanatory observations, 
so that my course may not hereafter be misunderstood. « 
Amid a great variety of important appropriations, this bill contains an appro- 
priation " for the completion of the Washington aqueduct, 8500,000, to be ex- 
pended according to the plans and estimates of Captain Meigs, and under his 
superintendence; provided, that the office of engineer of the Potomac water 
works is hereby abolished, and its duties shall hereafter be discharged by the 
chief engineer of the Washington aqueduct." To this appropriation, for a 
wise and beneficial object, I have not the least objection It is true I had 
reason to believe, when the last appropriation was made of $800,000, on the 
12th June, 1858, "for the completion of the Wash ington aqueduct," this would 
have been sufficient for the purpose. It is now discovered, however, that it will 
require $500,000 more "for the completion of the Washington aqued/uct," and 
this ought to be granted. 
The Captain Meigs to whom the bill refers is Montgomery C. Meigs, a cap- 
tain in the corps of engineers of the army of the United States, who lias super- 
intended this work from its commencement, under the authority of the late 
and present Secretary of War. 
Had this appropriation been made in the usual form, no difficulty could have 
arisen upon it. This bill, however, annexes a declaration to the appropriation 
that the money is to be 'expended under the superintendence of Captain Meigs. 
The first aspect in which this clause presented itself to my mind was, that it 
interfered with the right of the President to be " commander-in-chief of the 
army and navy of the United States." 
If this had really been the case, there would have been an end to the ques- 
tion. Upon further examination, I deemed it impossible that Congress could 
have intended to interfere with the clear right of the President to command the 
army, and to order its officers to any duty he might deem most expedient for 
the public interest. If they could withdraw an officer from the command of the 
President, and select him for the performance of an executive duty, they might, 
upon the same principle, annex to an appropriation to carry on a war a condi- 
tion requiring it not to be used for the defence of the country unless a particu- WASHINGTON AQUEDUCT. 
23 
lar person of its own selection should command the army. It was impossible 
that Congress could have had such an intention, and therefore, according to my 
construction of the clause in question, it merely designated Captain Meigs as its 
preference for the work, without intending to deprive the President of the power 
to order him to any Other army duty for the performance of which he might 
consider him better adapted. Still, whilst this clause may not be, and I be- 
lieve is not, a violation of the Constitution, yet how destructive it would be to 
all proper subordination, and how demoralizing its effect upon the morale, of the 
army, if it should become a precedent for future legislation. Officers might 
then be found, instead of performing their appropriate duties, besieging the 
halls of Congress for the purpose of obtaining special favors and choice places 
by legislative enactment. Under these circumstances, I have deemed it but 
fair to inform Congress that, whilst I do not consider the bill unconstitutional, 
this is only because, in my opinion, Congress did not intend, by the language 
which they have employed, to interfere with my absolute authority to order 
Captain Meigs to any other service I might deem expedient. My perfect right 
still remains, notwithstanding the clause, to send him away from Washington 
to any part of the Union to superintend the erection of a fortification, or on 
any other appropriate duty. 
It has been alleged, I think .without sufficient cause, that this clause is un- 
constitutional, because it has created a new office, and has appointed Captain 
Meigs to perform the duties. 
If it had done this it would have been a clear question, because Congress 
have no right to appoint to any office, this being specially conferred upon the 
President and Senate. It is evident that Congress intended nothing more by 
this clause than to express a decided opinion that Captain Meigs should be con- 
tinued in the employment to which he had been previously assigned by com- 
petent authority. 
It is not improbable that another question of grave importance may arise out 
of this clause. Is the appropriation conditional, and will it fall provided I do 
not deem it proper that it shall be expended under the superintendence of Cap- 
tain Meigs ? This is a question which shall receive serious consideration, 
because upon its decision may depend whether the completion of the water 
works shall be arrested for another season. It is not probable that Congress 
could have intended that this great and important work should depend upon the 
various casualties and vicissitudes incident to the natural or official life of a 
single officer of the army. This would be to make the work subordinate to the 
man, and not the man to the work, and to reverse our great axiomatic rule of 
" principles not men." I desire to express no opinion upon the subject; should 
the question ever arise it shall have my serious consideration. 
JAMES BUCHANAN. 
Washington, June 26, 1860. 24 
WASHINGTON AQUEDUCT. 
B. 
MEMORANDUM OF INSCRIPTIONS ON STRUCTURES CONNECTED WITH THE 
WASHINGTON AQUEDUCT. 
1. In the gate-house at Great Falls: 
" Washington Aqueduct, 
Projected by Captain Montgomery C. Meigs, 
U. S. Corps of Engineers, Chief Engineer. 
Begun November 8, 1853, by Franklin Pierce, 
President of the United States. 
This stone is erected in the unfinished gate-house 
at the Great Falls of the Potomac, 
June 10, A. D. 1858, James Buchanan 
being President of the United States. 
Captain M. C. Meigs, Chief Engineer of the Washington Aqueduct. 
The assistant engineers have been 
W. H. Bryan, C. Crozet, C. G. Talcott, A. L. Rives, 
W. R. Hutton, E. T. D. Myers. 
Cost of the work as estimated, 1853, $2,300,000. • 
Actual cost when finished, $ 
Dei gratia. 
Esto perpetua." 
2. On waste-weir No. 1: 
" Waste-weir No. 1. 
Washington Aqueduct, 
Captain M. C. Meigs, Chief Engineer." 
3. On bridge No. 1: 
" Washington Aqueduct, 
Captain M. C. Meigs, Chief Engineer. 
Anno Domini 1857. 
Bridge No. 1." 
4. On bridge No. 2 : 
" Washington Aqueduct, 
Captain M. C. Meigs, Chief Engineer. 
Anno Domini 1857. 
Bridge No. 2." 
5. On culvert No. 12: 
"Washington Aqueduct, 
A. D. 1856. 
Captain Montgomery C. Meigs, Chief Engineer. 
No. 12. 
May, 1856." 
6 On bridge No. 3: 
"Washington Aqueduct, 
Chief Engineer, 
Captain Montgomery C. Meigs, 
U. 8. Corps of Engineers. 
Division Engineer, 
Charles G. Talcott, C. E. 
Bridge No. 3. 
• June 9, 
A. D. 1858." WASHINGTON AQUEDUCT. 
25 
7. On Cabin John bridge (on the east abutment:) 
"Union Arch. 
Chief Engineer, Captain Montgomery 
C. Meigs, U. S. Corps of Engineers. 
Esto perpetua." 
(On the west abutment:) 
" Washington Aqueduct, 
Begun A. D. 1853. President of the U. S., 
Franklin Pierce. Secretary of War, 
. Building A. D. 1861. 
President of the U. 8., Abraham Lincoln. 
Secretary of War, Simon Cameron." 
(On one of the arch stones:) 
"M. C. Meigs, 
Chief Engineer. 
Washington Aqueduct. 
A. D. 1858. 
Fecit." 
8. On sluice tower at receiving reservoir: 
. "Washington Aqueduct, 
Built by order of the Congress of the United States, for bringing water into 
Washington. 
Begun A, D. 1853, on the 8th day of November. 
Water delivered in Washington 
from this reservoir A. D. 1859, 
on the 3d day of January. 
From the Potomac river A. D. , on the day of . 
151 feet above 0 of the Washington Aqueduct, or 150 feet above ordinary high 
water at Washington. A. D. 1858. 
Captain M. C. Meigs, Chief Engineer." 
9. At the distributing reservoir the rise of each of the thirty-nine iron steps 
leading down into the pipe-vault is composed of the letters 
" M. C. Meigs." 
10. On bridge No. 6, across Bock creek, (two inscriptions, one on each side :) 
" Washington Aqueduct. 
A. D. 1859. 
Chief Engineer, Captain M. C. Meigs, 
U. S. Corps of Engineers. 
Division Engineer, E. T. D. Myers, C. E. 
Iron Founders, A. & W. Denmead & Sons." 
11. On waste-weir No. 3, between the two reservoirs : 
"Washington Aqueduct, 
Waste-weir No. 3. 
Dec., 1858. 
Captain M. C. Meigs, Chief Engineer. 
W. R. Hutton, C. E., Division Engineer." 
12. In addition to the above: 
"Washington Aqueduct, M. C. Meigs," 
is stamped upon nearly every piece of iron or brass connected with the derricks 
and machinery used for the construction of the work, and the hoisting gear of 
all stop-cocks and water-gates. 26 
WASHINGTON AQUEDUCT 
LETTER FROM GENERAL M. C. MEIGS TO THE SECRETARY OF THE 
INTERIOR, DATED AUGUST 27, 1863. 
C. 
t Quartermaster General's Office, 
Washington, August 21, 1863. 
Dear Sir: I enclose copy of a letter received to-day from Lewis Baker, a 
person unknown to me. 
I have no further connection with the water works than a natural desire that 
they shall be well and economically completed. The office contains complete 
plans of every detail of my designs, which Congress, by a law, directed to be 
followed in completing the work. None of the work can need to be taken up. 
That portion from the receiving reservoir to the city, which has been in use for 
several years, without costing a dollar for repairs beyond filling up washes of 
the new embankments, is exposed to a greater head or pressure of water than 
any other portion of the conduit or work. It is built precisely like the rest of 
the work not yet brought into use. One portion of the conduit about culvert 18 
was put hastily into a fresh embankment in wet weather to avoid interruption 
by a lawsuit. The embankment settled and this portion of the work cracked. 
These cracks were being repaired when I left the work. No other part of the 
work can need any but ordinary repairs. 
On the Croton and other aqueducts annual repairs of cracks caused by settle- 
ment are necessary. On the part of the Washington aqueduct in use no such 
repairs, after the first month's use, have been needed or made within my knowl- 
edge. 
Before introducing water from the Great Falls, the whole interior of the con- 
duit ought to be carefully inspected, and all shrinkage or settlement cracks 
should be carefully pointed with cement. If this is done well, no repairs will 
be needed to the conduit for years. If the plans prescribed by law are followed 
(see act of 1860, chap. 211, page 106, vol. XII) with reasonable skill and 
ordinary fidelity, the work will be durable, substantial, and satisfactory. Any 
change will involve additional expenditure, and require special legislation to 
legalize it. 
Having made all the designs and plans of this work ah initio, having devoted 
many years' of labor to its construction, I desire to see it completed as designed, 
and am willing to remain responsible for its success, if so completed. 
From any change I anticipate ill results-if not to the work, at least to the 
treasury. 
I am, very respectfully, your obedient servant, 
M. C. MEIGS, 
Quartermaster General, late Chief 
Engineer Washington Aqueduct. 
The Secretary of the Interior. 
D. 
REPORT OF S. SEYMOUR TO THE HONORABLE J. P. USHER, ASSISTANT 
SECRETARY OF THE INTERIOR, IN RELATION TO THE PROPOSED DAM 
AT THE GREAT FALLS OF THE POTOMAC. 
Washington, October 16, 1862. 
Sir : In obedience to your request, I accompanied Mr. Hutton, the chief 
engineer, over the Washington aqueduct, on the 9th instant, to the High Falls 
of the Potomac, and spent several hours in examining with him the topography WASHINGTON AQUEDUCT. 
27 
of the country and the flow of water, both at the falls and at the head, and 
down both sides of Conn's island. 
Mr. Hutton explained to me very frankly and fully the plans that have been 
adopted with reference to obtaining an adequate supply of water for the Wash- 
ington aqueduct from the Potomac at that point. As my views differ in many 
respects from those of Mr. Hutton, as well as from the plans heretofore adopted 
and approved by him, I will proceed to explain them to you, and to make such 
suggestions for your consideration as, in my opinion, the importance of the sub- 
ject demands. 
The conduit of the Washington aqueduct is considerably larger than any 
other now in use for a similar purpose in this country. It is a circle of nine 
feet diameter in the clear, and has an inclination of nine and one-half inches per 
mile. The transverse sectional area is 63 square feet. Assuming that the 
available area for water-way is only fifty s quart feet, and that the average 
velocity of the current will be only two miles per hour, it will then discharge 
nearly one hundred, million gallons every twenty-four hours. 
Although this quantity of water may be much greater than will be required 
for many years, yet it is unquestionably expedient that a full supply at the 
fountain head should be secured for all time. 
It is proposed to divert a sufficient quantity of water from the Potomac at the 
Great Falls for the supply of the aqueduct* by means of a dam across the 
branches or channels of the river running each side of Conn's island. The spe- 
cification for1 this dam reads as follows : " The dam will be an embankment of 
rubble stone, with a top width of (20) twenty feet, a slope on the upper side of 
one to one, and on the 'lower side of five to one. It will be made with large 
stones, the spaces filled with smaller ones, so as to form a compact mass (8|) 
eight and one-half feet from the upper slope, and laid parallel with it, there will 
be three feet in thickness of spalls and gravelling. Care will be taken to place 
on the outer surface of the bank stone sufficiently large to resist the action of 
high freshets," &c. 
The Great Falls of the Potomac affords one of the finest natural water-powers 
for manufacturing purposes in the country, and perhaps in the world. The gov- 
ernment, therefore, in appropriating any considerable portion of this water to its 
own use should do so in a way to inflict as little injury as possible to the rights 
of the owners of the remaining water, or, in other words, the dams, and other 
structures that may be required for the purposes of the aqueduct should be so 
planned and constructed as to be permanent and imperishable in their character, 
to permit of no unnecessary waste of the water, and to allow, as far as practi- 
cable, the convenient and unobstructed use of the remaining water by the legiti- 
mate owners for manufacturing or other purposes. From the examination and 
reflection that I have been able to give the subject, I am fully convinced that 
the above objects will not be fully accomplished by the present plans. 
A large island, containing about (200) two hundred acres, (known as Conn's 
island,) divides the waters of the Potomac a little above the Great Falls.-By far 
the largest portion of the water flows upon the Virginia side of this island, and 
it is upon this side that water for manufacturing purposes can be taken from 
the river to the best advantage. 
The aqueduct enters the river from the Maryland shore at a point nearly op- 
posite the foot of Conn's island, and therefore draws the water in the first in- 
stance from that portion of the river which flows upon the Maryland side of the 
island. 
Unfortunately, however, in my opinion, there are two facts existing which 
will prevent the water that naturally flows upon this side of the island from fully 
supplying aqueduct, except in cases when the river is above low-water 
mark-these are, first, that during stages of extreme low water there is appa- 
rently not a sufficient quantity running in the Maryland channel (exclusive of 28 
WASHINGTON AQUEDUCT. 
the waste water from the Chesapeake and Ohio canal) to fill the aqueduct; 
and, second, that the level of the water at the head of the island during low 
stages- is, as I am informed by Mr. Hutton, only five feet above the bottom of 
the mouth of the conduit, which fact shows that, whatever might be the quantity 
of water running in the Maryland channel, there is not sufficient head, (after 
allowing one-half of a foot as a necessary inclination for the requisite velocity of 
current,) to fill the aqueduct above its centre line. 
It will therefore be seen that, should the dam across the Maryland channel, 
immediately below the mouth of the aqueduct, be constructed sufficiently high 
to raise the water to the crown of the conduit, it would only cause the water to 
set back and flow down the Virginia channel. To obviate this the present plan 
contemplates the construction of an additional dam across the Virginia channel 
of the same height. 
If there was sufficient elevation at the upper end of the island to fill the 
aqueduct, the deficiency of water, if any, in the Maryland channel might be 
remedied by deepening the head of the channel, and thus diverting a portion of 
the water from the Virginia side of the island; but as it is, this is evidently im- 
practicable. If the grade line of the aqueduct had been depressed four or five 
feet there would have been no necessity for constructing a dam across the Vir- 
ginia channel. Why this was not done is not apparent to me. 
I consider both the location and plan of the present dam as highly objec- 
tionable. The line of the dam is quite oblique to the channel, and forms an 
acute angle of, say, about (50°) fifty degrees, with the Maryland shore, looking 
up the river, and on that account wijl have a tendency to throw the flood wood 
over towards the entrance of the aqueduct, and upon that portion of the dam 
nearest to it. The dam is also required to be much longer, on account of this 
obliquity, than it would be if located directly across the river, 
The effect of raising the water four or five feet at the upper end of the island, 
by means of perfectly tight and permanent dams intersecting it upon each side, 
would, in my opinion, be to endanger the safety of the island itself during high 
floods. 
The only apparent motive for the present location is to reach a piece of land 
owned by the government on the Virginia side of the river, with a view per- 
haps of evading the question of damages to the owners of the water-power be- 
low that point. Were this question of damages entirely settled and out of the 
way, I should, so far as I can judge without having made a critical examination 
of the Virginia shore, consider the most natural location of the dam to be in the 
form of an arc, extending from the mouth of the aqueduct to a point on the 
Virginia shore below the mouth of the old canal, which happens to be almost 
directly opposite. 
The plan of the dam is, in my opinion, open to at least two very serious ob- 
jections, to wit: Want of stability, and a want of that degree of compactness 
which is necessary to prevent the wastage of a large amount of water by filtra- 
tion. Both of these objections should, in my opinion, weigh very seriously with 
the government, as well in regard to the question of ultimate economy in the 
use of the water- as in the question of present damages for the diversion of a 
much larger amount from the Virginia channel than they actually use, and the 
risks taken by the owners of manufactories below on account of the danger of 
the carrying away of the dam during high floods. 
I observed at the head of Conn's island a large amount of floatsome, piled 
several feet in height, and composed of large trees and timbers, some of which 
appeared to be portions of the Harper's Ferry railroad bridge, in parts of sec- 
tions firmly bolted together. Much of this was evidently deposited during the 
unusually high flood of last spring, and a much larger quantity undoubtedly 
passed down the river alongside of the island. The water during that flood was, 
as I am informed, only about two feet above the top of the riprap dam, which WASHINGTON AQUEDUCT. 
29 
is now completed some six hundred feet in length across a portion of the Maryland 
channel. This portion of the dam shows very little damage from the flood, on 
account of the abundance of water-way both in the Virginia channel and those 
portions of the Maryland channel (several hundred feet in width) at each end 
of the dam. If these channels had been obstructed by a similar dam, extending 
entirely across the river, I am quite confident that scarcely a vestige of them 
would have remained after the waters had subsided. * 
If this first objection to the plan should prove to be well founded, then the 
question may, of course, be considered as disposed of without discussing the 
second objection. But admitting, for the sake of the argument, that the dams 
will stand permanently, 1 submit in the greatest confidence that they will, in 
low stages of water, pass a much larger quantity through them than they will 
divert to the aqueduct. I know of several instances where, at the present time, 
living streams are running, and have been running for years, through rock em- 
bankments of from fifty to one hundred feet base, and when culverts were dis- 
pensed with by my own direction as an unnecessary expense. 
My experience and observation, therefore, force me to the irresistible conclu- 
sions, with reference to the dam as now proposed to be constructed-first, that 
it will not during low stages of water produce sufficient head to fill the conduit; 
and, second, that in stages of high water, when no dam is needed, it will be car- 
ried away by the floods. I would therefore advise the construction of a dam of 
the most substantial solid masonry. 
If it should be determined that the water naturally flowing upon the Mary- 
land side of Conn's island will be sufficient, at all stages, to afford a full sup- 
ply for the aqueduct, and that, in obtaining this supply, it is inexpedient to 
interfere in any manner with the natural flow of the water in the Virginia chan- 
nel, this result may at any time be accomplished by extending a wing dam from 
the head of the island up the river to a point giving sufficient head, and locating 
it in, such a manner as to produce the same natural division of the water as is 
now secured by the island. This expense, however, or any other, for the pur- 
pose of obtaining a greater head than four feet, may very well be deferred so 
long as it is found that one-half the capacity of the upper end of the conduit, in 
addition to the present reservoir below, affords the required supply. Should the 
plan of the dam be changed from loose, or riprap, to solid masonry, and the lo- 
cation extending across the river below the island be adopted, then it will only 
be necessary to extend the dam to a point opposite the lower end of Conn's 
island, and there connect it temporarily with the island in order to secure all 
the water flowing down the Maryland channel, and to raise it sufficiently high 
to furnish a supply for present purposes, equal to one-half the capacity of the 
conduit. 
The above suggestions and recommendations are submitted to the department 
with much hesitation, for the reason that they differ so materially from the views 
of the present chief engineer, and from the plans heretofore recommended by 
Captain Meigs and adopted by the government. 
The following extract from the specifications shows, however, that Captain 
Meigs did not regard the proposed dam as an entirely permanent structure: 
. " For thirty feet above the upper edge of the dam all materials will be re- 
moved for a depth of four feet below the level of water in the pool to form a 
boat channel that can be used in replacing uny of the stones carried away by 
high freshets." 
The following extract from a paper prepared by the same engineer in April, 
1858, also shows that he had not, in his own opinion, selected the best site for 
the dam with reference either to its cost, or the damages to the proprietors of 
the water-power: 
"The plan of this dam, shown upon the drawings in the office, may possibly 
be modified, as negotiations are now in progress with the owners of the water- 30 
WASHINGTON AQUEDUCT. 
power on the Virginia shore which may result in the acquisition of a better 
site for the dam than the only one heretofore available, and in the revision of 
the location so as to reduce the cost of the dam, and at the same time to construct 
one which will render the water-power more available to the proprietors." 
There is, perhaps, no subject connected with the profession of civil engineer- 
ing, the investigation of which has occupied more time and attention, and in- 
volved the expenditure vf larger amounts of money, than the one involving the 
stability and imperviousness of structures required to resist the action and pres- 
sure of water. Amounts almost fabulous have frequently been expended by en- 
gineers of acknowledged reputation, and upon plans apparently unexceptionable, 
without accomplishing the desired result. 
The vast destruction of property by the unprecedented floods of the past few 
years in different parts of the country, and the failure of structures that had with- 
stood the action of the water for a quarter of a century, and were supposed to be 
impregnable, should admonish engineers to use the greatest caution in the recom- 
mendation of plans and specifications for structures that are to be at all exposed 
to the action or pressure of water. 
If, in the face of these facts and experiences, it shall now be found that a pro- 
miscuous mass of loose angular rocks, interspersed with a thin section of spalls 
and gravel, will successftdly withstand the floods of the Potomac, and at the 
same time be impervious to water, the fact may well be regarded as an engineer- 
ing paradox. 
In a matter involving so large an expenditure of money, and results so import- 
ant both to the government and the cities of Georgetown and Washington, I 
would respectfully recommend the department, before proceeding further under 
the present plans, to avail itself of the best experiences, and the advice of the 
best engineering talent in the country. The time and expense required to do 
this will be trifling in comparison to the importance of the questions and results 
involved. 
I will also take the liberty of calling the attention of the department to tfhat 
I regard as a serious defect in the plan of completing the large distributing res- 
ervoir near Drovers' Rest. The present plan contemplates the interior slopes 
" to be faced with broken stone." It has been found that this facing will not 
answer the purpose, and consequently it has been necessary, in the reservoirs of 
the Croton aqueduct, to substitute a solid slope wall, either pointed or laid 
throughout with hydraulic cement. 
I have the honor to be, very respectfully, your obedient servant, 
S. SEYMOUR, 
Consulting Engineer, 411 Pennsylvania Avenue. 
To the Honorable 
J. P. Usher, 
Assistant Secretary of the Interior. 
E. 
EXTRACTS FROM TESTIMONY TAKEN BEFORE COMMISSIONERS IN RELATION TO 
THE DAM AT GREAT FALLS. 
Testimony of James Slade, Esq. 
Question. What is your general experience and practice as a scientific en- 
gineer, so far as your experience and knowledge have been applied to depart- 
ments of engineering, and in what special departments of civil engineering have 
you been Employed ? 
Answer. I hav.e been the city engineer of Boston somewhere about seven WASHINGTON AQUEDUCT. 
31 
years, having charge of the water works principally about six years of that time. 
I made the original surveys for the water works of the city of Baltimore, and 
the plan that was adopted, and during the construction of the water works the 
city government passed an ordinance authorizing the commissioner to employ 
me as consulting engineer, and I was such for nearly three years. I was en- 
gaged upon the construction of the Boston water works from the foundation of 
the reservoir, having that in charge as resident engineer, and superintended the 
laying of two great mains. I was engaged there some two years. I was also 
engineer of, and made plans for the construction of the Hartford water works. 
I took exception with the commissioners in regard to plans of engines, and we 
parted on that. I also made surveys and plans with reference to the extension 
of the water works in Cohoes, and was consulting engineer. I also made esti- 
mates and calculations for the water-power company in Cohoes, as to their water- 
power, giving Mr. Young a detailed estimate of what they had there. I was 
consulted by the contractors of the Brooklyn water works on several points; 
also, in reference to the water works of St. John's, New Brunswick, I do not 
know how many times, and although I did not visit there myself I sent on my 
assistants. Three of the commissioners came on to Boston to see me, and I 
proposed an improvement there which they adopted, and which operated as they 
desired. I learned them how to get a supply of very excellent water. I have 
acted as consulting engineer on various matters for many years past. I was 
resident engineer upon a dam built near Island Ann, Boston, of which Colonel 
Boardman was chief engineer. I was engaged on the construction of the Albany 
water works, from very near the commencement down to the introduction of 
water, or until a few days of that event, when I resigned my position. 
Mr. Stanton.-Question. What would be the character of the riprap or rubble 
dam as to tightness ? 
Answer. Such as is now constructed, some 600 feet in length, I should con- 
sider so imperfect that I should not like to trust it as a dam in case of a freshet. 
Question. There is no sluice-way mentioned in the plan, I believe. Have 
you formed any estimate of what the construction of such a sluice-way would 
cost ? 
Answer. I have not. A riprap dam could not be made to hold the water. The 
circular dam, in my opinion, would be by far the best adapted to the wants of 
both parties. It would be much less liable than the others to break away. The 
tendency of the water on the circular dam would be to consolidate it, and'it 
would certainly give more overfall than a straight one. The water would not 
rise so high upon it, and it would be less liable to break $way in case of freshet. 
It would require an increase of length in the bulkhead; that is, I mean some- 
thing more than they now have. The construction of that circular dam would 
not be of so much injury to the company as either of the others. I cannot form 
any idea of what it would cost to put the dam there. 
Mr. Bradley. It makes no provision for bulkhead upon the main land. They 
would have to put up a bulkhead for their own protection, which would only be 
required in case of a flood. 
Mr. Childs. Do you mean to say it would not be safe to erect large mechani- 
cal works with that kind of dam-rubble or riprap ? 
Answer. It would not be safe to have a rubble dam there. I should not be 
disposed to trust anything below it. The low dam mentioned in the plan would 
be much more likely to stand than the high one. 
Mr. Walker.-Question. With the knowledge you have of this matter, do you 
think that the manufacturing capitalists of New England would deem it secure 
to invest a large amount of capital in works with a rubble dam like this proposed 
by the government ? , 
Answer. I think they would not certainly. 32 
WASHINGTON AQUEDUCT. 
Mr. Stanton.-Question. Would it not be necessary for the dam to be entirely 
tight in order to secure it at all ? 
Answer. I judge it would. A solid stone wall might be made of the rubble- 
stones, provided they were cemented and made tight in that way. A large mass of 
ice coming down the Potomac would carry away the smaller stones and tend to 
destroy the rubble dam. The specifications, however, which you now show me, 
describe a different dam from the one I am testifying upon, and different from 
that now erected. 
Question. What proportion of the weight of such stone as is described there is 
sustained by the water: one half, or do you know the specific gravity of that 
kind of stone? 
Answer. I do not know exactly, but suppose it must be something near the 
same as granite. Granite weighs something like 170 pounds to the cubic foot, 
and the water weighs 62 £ pounds. 
Question. Would you advise the building of a riprap dam, such as is de- 
scribed, across the Virginia shore to ibis point? 
Answer. I would not. I cannot conceive any object to be attained by build- 
ing a dam of masonry on one side and riprap on the other. 
Question. Could the stones of the riprap settle, all being separate, horizon- 
tally, or could they settle perpendicularly? 
Answer. They could settle some, possibly. A dam twenty-five feet high, or 
thereabouts, might settle two or three inches. There would be liability to loose- 
ness in the substructure in the riprap, and spaces. There would fie flows all 
through the rock structure of the dam all the time. You cannot pile rough stones 
up in any possible manner without having spaces between them. 
Testimony of Samuel McElroy, Esq. 
Question. Please state what experience and study you have had as a civil 
engineer, more especially with reference to water-courses and the construction of 
dams, or to the taking of water, either for a mill-power, canals, or aqueducts ; and 
also more especially to steam-power as well as water-power. 
Answer. I have been employed as an assistant engineer of the Erie canal 
enlargement; also as an officer of the engineer corps of the navy, and as such 
engaged on the plans, erection, and operation of steam machinery ; was principal 
assistant engineer of the New York navy yard, for several years in charge of the 
prominent structures there; was associate engineer in surveys for the Niagara 
ship-canal, and on surveys and plans for the Rochester water-works; have been 
connected with the Albany, Hamilton, and other water-works ; was chief engineer 
of the Brooklyn water-works at the time the plans and specifications were pre- 
pared and the work put under contract; have also been engaged iii the measure- 
ment of rivers for the determination of tidal currents, and in the preparation of 
papers for prominent magazines of the country on hydraulic engineering, 
which I have made a special study; have also been in charge of railroads as 
chief engineer. 
Question. Have you had personal observation and more or less examination 
of the site of the Great Falls on both sides of the river, including the existing 
canal of the Potomac company, and the works of the Washington aqueduct, as 
connected with the river at that place ? 
Answer. Yes, sir. 
Question. Sufficiently to enable you to speak of special localities designated 
on the map, to be made the subject of inquiry in the examination of witnesses ? 
Answer. So far as general examination will permit. 
Question. I now ask your attention to the dpm projected next above, which 
is marked A on the map. What would be the effect of the dam constructed on 
that oblique line, proceeding in a straight line of solid masonry from the Mary- WASHINGTON AQUEDUCT. 
33 
land bank to Conn's island, and from Conn's island, in riprap, to the Virginia 
bank ? What would be the effect of that dam upon the water-rights and water- 
power of the company, first as to the diversion of yvater ? 
Answer. The same effects in general as described for the lower dam, with 
this exception: If we assume that the crest of the dam is flowing, the waste 
would be in proportion to the length, which would be in the proportion of about 
1,200 on the Virginia to 1,510 on the Maryland side, in length ; but I do not think 
that the riprap dam on the Virginia side would be tight. It would involve, I think, 
two contingencies to the company ; one is, the construction of the wing-dam to 
Conn's island, in order to catch the water which is wasted through the riprap 
dam; and the other, the construction of a hydraulic canal from the mouth of the 
present canal to the dam. In order to secure the water from the line A, I think 
they would need both of those structures. 
Question. What proportion of leakage or wastage would the portion of it 
which is riprap involve ? 
Answer. If a channel above the dam were not to be blasted out across Conn's 
island, as described in these specifications, so that the crest of dam on Conn's 
island is about the same level as Conn's island itself, I doubt very much whether 
any water would be thrown on the Maryland side, except the spill of the dam 
on that side. I think the dam would operate as our railroad riprap culverts do, 
and waste the flow of the river-certainly a large portion of it. 
Question. What is the operation of ordinary railroad riprap culverts ? 
Answer. They are put in for the purpose of passing streams under railroad 
embankments, particularly for torrent streams. 
Question. Are they, or not, a substitute for culverts of masonry ? 
Answer. Yes, sir. 
Question. I understand that in your experience ripraps have been used for 
passing mountain streams under railroads, &c., as substitutes for culverts; that 
is, on the same principle as French drains, as they are called. 
Answer. Very much so. 
Question. Are they not subject to being stopped up by silt flowing into them? 
Answer. No, sir ; they always clear themselves. The floods keep them clean. 
Question. In that event are not the stones loosely thrown together ? 
Answer. They are packed as closely as they can be made with an ordinary 
dump. They are dumped in-all sizes. 
Question. Have you looked at the specifications of this riprap dam? 
Answer. Yes, sir. 
Question. Is that such a dam as is made under railroad embankments for 
mountain streams ? 
Answer. As far as its tightness is concerned, I think it would come under the 
same general law. It is more carefully made, however, and has the addition of a 
short layer of smaller stones; but the relative tightness would be a mere ques- 
tion of spaces. 
Question. In these ripraps of which you spoke are the spaces filled in with 
smaller stones so as to form a protection of three feet of thickness of gravelling 
upon them? 
Answer. If the relative sections are compared, I think the relative tightness is in 
favor of the culvert. As I understand it, this dam is but twenty feet across the 
head. The culverts to which I have made reference are in all cases a great deal 
longer. The structure should be made very tight, so as not to settle. It would 
not do to fill up on a shaky foundation. 
Question. So that work of this description would afford only a medium ob- 
struction to the passage of the water? 
Answer. Yes, sir. 
Question. In ordinary times would the water flow through almost as fast as the 
supply ? 
Mis. Doc. 83- 3 34 
WASHINGTON AQUEDUCT. 
Answer. That is a matter that would depend upon the velocity of approach 
more than anything else. 
Question. My object is to see what the effect of this riprap dam "A" would be 
in preventing the flow of water to the company's grounds as they now stand, and 
if it is so opened as to operate more efficiently in passing water than the ripraps 
under the railroads. I want to know to what extent it would impair the value 
of this water privilege by shutting off the water. Have you any memorandum 
of the velocity of the stream there ? 
Answer. No, sir. The cases to which I refer are mainly in torrent streams, 
which are small streams in warm weather, and in the spring are torrents. And the 
relative level at the dam you speak of would, of course, depend upon the quan- 
tity of water coming down the river and the velocity of approach. The water 
would pile up on the upper stream side. 
Question. You spoke of the accumulation of rocks in riprap as a substitute for 
culverts under embankments of railroads; have you special knowledge of such 
« ubstitutes ? 
Answer. Yes, sir; there is one case in the New York and Erie railroad, near 
Hornersville, in which there is an embankment of about fifty feet in height, in 
which the base line of the culvert, that is, riprap work, is about 200 feet in 
length, which passes a creek. 
Question. Does that riprap work constitute the foundation in the bed of the 
creek, or river, upon which the entire embankment rests? 
Answer. Yes, sir; there is another case of much larger character than this on the 
Cascade creek, in a gorge crossing, where the base is several hundred feet- 
nearly seven hundred feet in length. 
Judge Curtis. Question. In this case the riprap work is carried up much 
above the level of the water, I suppose? 
Answer. Yes, sir; the stream banks up. 
Question. In that case the water would be run over the dam. Of course, in 
the case of these culverts, it would run under ? 
Answer. That would depend upon the quantity of delivery and force of ve- 
locity of approach. 
Question. How much interstitial space must you allow for the delivery of the 
water? 
Answer. In those cases tunnels were built to aid the free discharge in case the 
water did not go through, but were not used. The riprap is carried up to meet 
extraordinary currents, but in the ordinary current the water flows through 
without any trouble. 
Question. Did I understand you that the flood cleanses them from silt ? 
Answer. Yes, sir; it has that effect. 
Question. Have you had any experience of the percolation or leakage through 
rubble-stone dams? 
Answer. The percolation of water through riprap dams? I have built a 
number of culverts to allow the escape of water. 
Question. Describe the nature of one of these substitutes. 
Answer. We would take the common stone and throw it in indiscriminately, 
making it pretty broad and pretty high, covering that with brush and leaves 
and then earth, and building the railroad bank right over it. 
Question. What was the magnitude of the structures? 
Answer. All heights, from five feet to, on the New York and Erie railroad, 
enormous heights and consequent breadth of base. One of them is over fifty feet, 
and another of them, at the cascade, of the height of 186 feet, where they built the 
whole bottom with loose rock, which allows all the water to flow through. There 
is more than one saw-mill above the railroad, and the stream is large. To guard 
against accidents that might arise, they built a tunnel through the permanent * 
hill outside, but the water has never yet come up to the tunnel. WASHINGTON AQUEDUCT. 
35 
Testimony of Marvin Porter, Esq. 
Marvin Porter, being duly sworn, doth depose and say, in answer to inter- 
rogatories proposed by the counsel for the claimants, as follows: 
1st interrogatory. What is your name, residence, and occupation ? 
Answer. My name is Marvin Porter; my residence, Davenport, Iowa; my 
occupation, civil engineer. 
2d interrogatory. How long have you been civil engineer, and what experi- 
ence have you had in that capacity? 
Answer. 1 have been engaged in civil engineering about twenty-four years, 
during which time I have had charge of one division on the Genesee Valley 
canal; the eidargement of the Erie canal, between Lockport and Rochester; 
in locating a portion of the Erie railroad ; location and construction of the Can- 
andaigua and Elmira railroad, and the Canandaigua and Niagara Falls railroad; 
and the Niagara Falls and Lake Ontario railroad; and two divisions of the 
Burlington and Bellows Falls railroad. 
3d interrogatory. Have you made the subject of hydraulic engineering your 
study? 
Answer. I have, so far as obtaining water for canals, and determining the 
flow of water in canals. 
16th interrogatory. Suppose the dams proposed by the government were to 
be built of riprap, what would be the effect on the waste of water ? 
Answer. It is very doubtful whether, in a low stage of the water, it would 
flow over the dam. It would probably all waste through the dam before it could 
be brought to the crest of the dam. I have frequently, in constructing rail- 
roads where the embankment was from 50 to 60 feet in height, across a stream 
of 15 feet wide, and water in ordinary stage 6 inches in depth, formed an em- 
bankment of rock for the first 30 or 40 feet in height. With a base 196 feet it 
would pass all the water through it without injury to the embankment, even in 
high stages of the water. I have also passed water through an embankment 
where the base would be 50 feet, where the water in high stage would be from 
51 to 6 feet above the bed of the stream embankment made in the same way as 
the dam of the government appears to be, of riprap. This method is frequently 
resorted to by engineers to save the expense of constructing culverts. 
The present riprap dam already constructed at Great Falls by the govern- 
ment is no better than those which we make for embankments I have described. 
The character of the work is the same ; that is, the stone are thrown in hap- 
hazard and filled up as best it can be done afterwards. 
Met pursuant to adjournment. 
February 2, 1863. 
Marvin Porter recalled. 
1st question. Have you made an examination of dam No. 1 on the Chesa- 
peake and Ohio canal? And if so, state what is its condition. 
Answer. I have examined dam No. 1 of the Chesapeake and Ohio Canal Com- 
pany, and find it more or less injured where the current strikes it directly; and 
that portion of the dam from the mouth of the feeder to the angle in the dam,, 
and also about one-half of that portion between the angle and the island in the 
river has been partially carried away from the lower side of the dam, the stone 
being thrown up in an irregular manner by the action of the water evidently, 
and many of them deposited in the bed of the river below. The water does not; 
rise to the top of the dam in this part of it, but passes through, showing the lines 
of the inner angle of the dam. The same may be said of some portion of the 
dam on the westerly side between the island and the Virginia shore. 
1 st cross-interrogatory. When did you make the examination 1 
Answer. On Saturday, the 31st day of January. 36 
WASHINGTON AQUEDUCT. 
The following testimony of Mr. John G. Stone, a former superintendent upon 
the " Chesapeake and Ohio canal," was taken in the same case, to show the insta- 
bility of the feeder dams constructed of "riprap" on the Potomac river. 
Witnesses for the United States. 
John G. Stone, being duly sworn, doth depose and say, in answer to interrog- 
atories proposed by Joseph H. Bradley, esq., counsel for the United States, as 
follows: 
1st interrogatory. What is your name, residence, and occupation ? 
Answer. My name is John G. Stone; my residence, Georgetown, D. C.; my 
occupation, a wood merchant. 
2d interrogatory. Were you at any time, and for how long a period, and in 
what capacity, employed on the Chesapeake and Ohio canal ? 
Answer. 1 was employed on said canal in the spring of 1832, as a volunteer 
rodman under Mr. Purcell and Mr. Cruger, civil engineers of that company, 
during the location of the canal, and afterwards as assistant engineer in the con- 
struction of the work; and, after the completion of the work, as division super- 
intendent, under Mr. Fisk; and afterwards, as general superintendent; so that, 
with an intermission of one or two years, I was employed there for about twenty- 
five years. 
Cross-examination Try J. B. Stewart, Esq., counsel for the claimants. 
1st cross-interrogatory. What is the special office of the dams on the canal ? 
Answer. They form feeders to supply the canal with water. 
2d cross-interrogatory. State specifically how each dam was built. 
Answer. The first and second dams were built with riprap stones. The 
third dam is the Harper's Ferry dam, built by the government; it is partly now 
a masonry dam. Dam No. 4 was built of timber filled in with stone, and re- 
placed by a masonry dam. Dam No. 5 is the same, a crib dam filled in with 
stone, and is now being replaced by a masonry dam. Dam No. 6 is a crib dam 
filled in with stone. Dam at Cumberland, called No. 8, is a masonry dam. 
3d cross-4nterrogatory. Why were dams Nos. 1 and 2 built differently from 
the others? 
Answer. I don't know any reason why, except that the riprap dams answered 
the purpose to raise the water a few feet, and the other dams were stronger and 
answered the purpose better to resist the water at a greater height. 
4th cross-interrogatory. Were all these dams built across the river? 
Answer. I am not certain about the Seneca dam; all the others are. 
Sth cross-interrogatory. To operate as canal feeders, how are dams 1 and 2 
arranged as to the line of the current? 
Answer. Dam No. 1 inclines up the river a little to an island, and then goes 
from the island straight across the river. Dam No. 2 inclines up the river. 
6th cross-interrogatory. How were dams Nos. 1 and 2 repaired, and how 
often ? 
Answer. Dam No. 1 has never been repaired since it was rebuilt with large 
stone. Before that it was repaired whenever the water would get extremely low 
in the river each year. Dam No. 2 would be repaired in the same way when- 
ever the water would get extremely low. 
7th cross-interrogatory. Were not dams 4 and 5 rebuilt of masonry to 
make them hold water and stand freshets? 
Answer. They were. The timbers were rotten-the dams required repairing, 
and the canal board concluded to rebuild them of masonry instead of having to 
repair them constantly. WASHINGTON AQUEDUCT. 
37 
8th.cross-interrogatory. How long after you repaired dam No. 1, as you 
have stated, did you continue as general superintendent? 
Answer. I am not certain, but think it was about three or four years. 
9th cross-interrogatory. Do you know whether that dam has been repaired 
since you were superintendent? 
Answer. I do not; I don't think it has. I have passed there repeatedly. 
F. 
COMMUNICATION FROM S. SEYMOUR, ESQ., TO THE SECRETARY OF THE 
INTERIOR, IN REFERENCE TO THE SPECIFICATIONS FOR THE COM- 
PLETION OF THE DISTRIBUTING RESERVOIR. 
Washington Aqueduct Office, 
May 18, 1863.* 
Sir : The specifications for the completion of the distributing reservoir, near 
Drovers' Rest, require the interior slopes to be faced with broken stone, as 
shown by the drawings. " Riprap will be composed of sound, hard, and dura- 
ble stone, in blocks not exceeding three inch nor less than one and a half inch 
cubes, to be spread evenly on the surfaces, which will first be trimmed to the 
proper slopes." 
I have always entertained the opinion that this finish would not be sufficient 
to protect the banks from the action of the water during high winds, and have 
incidentally stated my convictions in two communications to the department- 
one dated October 16, 1862, and the other dated April 24, 1863. 
Not feeling entirely willing, however, to take the responsibility of recom- 
mending a change in the specifications, in opposition to the views of the chief 
engineer, without first consulting other engineers of skill and experience in such 
matters, I addressed, under date of 11th instant, a communication, of which 
the following is a copy, to James P. Kirkwood, esq., the chief engineer of the 
Brooklyn water works, Alfred W. Craven, esq., chief engineer and commissioner 
of the Croton aqueduct, and James Slade, esq., city engineer of Boston, and 
engineer of the Boston water works. 
Washington Aqueduct Office, 
Washington, May 11, 1863. 
Dear Sir: The present specification for the receiving reservoir of the Wash- 
ington aqueduct requires that the interior slopes " shall be faced with broken 
stone in blocks not exceeding three inch nor less than one and a half inch cubes, 
to be spread evenly on the surfaces." 
The water surface of the reservoir will be about fifty acres, and will be very 
much exposed to high winds. 
Will you be good enough to inform me whether, in your opinion, this finish 
will afford an adequate and suitable protection to the banks, and oblige 
Yours, very respectfully, 
S. SEYMOUR, 
Consulting Engineer Washington Aqueduct, 
411 Pennsylvania Avenue. 
James P. Kirkwood, Esq , 
Civil Engineer, fyc., New York. 
Alfred W. Craven, Esq., 
Chief Engineer Croton Aqueduct. 
James Slade, Esq., 
City Engineer, fyc., Boston. 38 
WASHINGTON AQUEDUCT. 
The following are copies of replies received from Mr. Kirkwood and Mr. Cra- 
ven. Mr Slade's reply has not yet been received : 
30 Union Square, New York, 
May 14, 1863. 
Dear Sir : I have only to-night received your note of the 11th. 
The broken stone which you mention as specified for the water faces of your 
receiving reservoir is frequently applied on a bed for stone paving. I have 
never known loose stone of any size used by itself on the water slopes of any reser- 
voir, and I presume that I have seen the best in this country, and some of the 
best in Great Britain. Such a reservoir as you describe wants to be very care- 
fully paved to protect its banks from the effects of high winds. 
Very respectfully, 
JAMES P. KIRKWOOD. 
S. Seymour, Esq. 
Croton Aqueduct Department, 
Office of the Chief Engineer, 
May 15, 1863. 
Sir : Owing to my absence from the city your note did not reach me until 
this morning. 
In reply to your question, I beg to say that, with slopes of ordinary inclina- 
tion and banks of ordinary materials, I should think a common facing of broken 
stone inadequate as a protection; but without more specific data than are con- 
tained in your letter, I do not feel justified in giving an opinion on the question 
proposed. 
I am, very respectfully, your obedient servant, 
A. W. CRAVEN. 
S. Seymour, Esq., 
Chttf Engineer, fyc., Washington. 
Inasmuch as the opinions expressed by these gentlemen correspond with my 
own, as well as with those of every practical engineer with whom I have con- 
versed, I therefore respectfully recommend that the specifications be changed to 
something like the following : 
The interior slopes or water faces of the reservoir will be faced with broken 
stone six inches thick, upon which will be laid a rubble wall of one foot in 
thickness, to be composed of stone extending through the wall, laid at right 
angles with the slope, and sufficiently large to resist the action of the water. 
The face of the wall to be well wedged and pointed with pinners or spalls so 
as to prevent the water from displacing any portion of the wall or the broken stone 
underneath. The top of the wall will be connected with a pavement rounded over 
the upper front angle and extending three feet back on the top of the bank, the 
pavement to be six inches thick, and composed either of small field or quarried 
stone of uniform size compactly laid on their ends and well bedded to an uni- 
form surface in broken stone or clean, hard gravel. The top of the bank from 
the outer edge of the pavement will be finished with a slope of one in ten in- 
clining from the reservoir, so as to shed the surface water away from the reser- 
voir into drains prepared for that purpose. 
I suggest the above as merely a modification of the present specification, with 
a view of greatly increasing the permanency and value of the work, without 
adding materially, if anything, to its present cost. Were the work to be started 
anew, I would recommend, as a proper finish for the water faces, a thickness of 
at least eight inches of broken stone, and a slope wall eighteen inches thick, 
aid in mortar. WASHINGTON AQUEDUCT. 
The interior slopes of the reservoir should have a uniform inclination of two 
to one, if the plan of facing above is adopted. 
I have the honor to be, very respectfully, 
S. SEYMOUR, Consulting Engineer. 
Hon. J. P. Usher, 
Secretary of the Interior. 
Washington, May 21, 1863. 
p. S.-Since writing the foregoing I have received a letter from Mr. Slade, 
of which the following is a copy : 
Boston, May 19, 1863. 
Dear Sir: Yours of the 11th has been received. The facing for the 
reservoir, made of stones as you describe, will be totally inadequate, unless, 
indeed, they are laid up in full beds of cement, which, as I understand, is not 
intended, the waves will wash it down in a short time. I should not allow any 
stone in it of less than six inches depth, and the larger the better. 
Yours, truly, 
JAMES SLADE. 
S. Seymour, Esq., 
Consulting Engineer, Washington. 
G. 
PAPER IN RELATION TO THE RECEIVING AND DISTRIBUTING RESER- 
VOIRS, PREPARED BY MR. J. J. R. CROES, PRINCIPAL ASSISTANT EN 
GINEER, W. A. 
Department of the Interior, 
Office of the Washington Aqueduct, 
Washington, D. C., February 20, 1864. 
Sir : In accordance with your instructions, I have the honor to submit for 
your consideration the following notes on the receiving and distributing reser- 
voirs : 
RECEIVING RESERVOIR. 
The object proposed in the construction of the receiving reservoir at Powder 
Mill branch was twofold: first, to give storage capacity in case of accidents 
occurring to the aqueduct; secondly, to furnish a large area in which the water 
might have opportunity to remain comparatively quiet and deposit its impurities. 
The first object is, to some extent, accomplished, the capacity being, above 
the bottom of the aqueduct, one hundred and sixty-three million gallons. The 
experience of the past four years has shown that the hopes entertained of the 
purification of the water were not well grounded, and for the following reasons: 
Four or five streams are constantly discharging into the basin, each draining 
a hilly country, and consequently swollen and muddied by every rain. The 
hill-sides sloping up from all sides of the reservoir discharge their surface water 
into it. Every shower, therefore, brings in a supply of turbid water, which 
continues running for some days from the streams. The water, for the most 
part, is shallow ; the area, compared with the length of shore-line, small, and 
the banks unprotected from the wash of the waves. In a broad sheet of deep 
water, these reasons would not count for so much; but here is an area of fifty- 
three acres, with a shore-line of fifteen thousand feet, and a width varying from 
two hundred to five hundred feet. The wind, sweeping down through the 
gorges of the hills, dashes the waves against the shores unprotected from their 
action and stirs up the mud. 40 
WASHINGTON AQUEDUCT. 
The theory that the water from the aqueduct, entering the reservoir some 
three thousand six hundred feet from the outlet, would diffuse itself over this 
area, and deposit its sediment in the passage, is good, but, unfortunately in this 
case, the object is entirely defeated by the mountain streams and the immense 
unprotected shore-line. This might have been foreseen, and means taken to 
bring the water directly to the city from the Potomac without passing through 
this basin when muddied by the streams, and also to protect the shores with 
stone. 
But, independently of this consideration, a due regard to the liability to ac- 
cidents would demand that some provision for a separate supply should be made. 
Should the dam, for instance, give way, there would be no means of procuring 
water in the city, the conduit discharging the water from the river directly into 
this reservoir. Such an accident, though not very probable, is by no means 
impossible. There are now, and have been for some time, two streams passing 
through the dam, but as yet doing no damage. 
At present the conduit passes through a rock tunnel, six hundred and twenty- 
six feet in length, to reach the upper end of the reservoir. Midway in this 
tunnel a large chamber is excavated, and a waste-weir built, to lead off the 
water from which a drift, three hundred and fifty feet long, is tunnelled through 
the rock, and walled and arched with masonry. 
From where the conduit line would diverge to form the connection with the 
conduit below the reservoir, the line, as constructed, has cost $37,000. To 
have built it directly to form such connection would have cost, at the prices 
then paying, $61,000-a difference of $24,000. Now, the same work, with the 
necessary additional gate-house, is estimated to cost $99,200, or, altogether, 
$75,200 more than it should have done at first. The necessity for it is actually 
no greater now than it was then. Only it is more obvious, after the experience 
of a few years. 
The distributing reservoir at "Drovers' Rest" is, in form, nearly a rectangle 
2,250 feet long, and about 850 feet wide at the flow line, having forty-four acres 
of water surface, a depth of water ot eleven feet, and capacity of 150,850,000 
United States gallons. It is divided into two parts by an embankment running 
across it-the upper or western division having an area of twenty-five acres, and 
the lower or eastern nineteen acres. 
The inner slopes, as originally designed, were to be partially covered with 
a riprap of small, broken stone. 
Three changes are proposed in the plans for this structure. 
The first, now carrying into execution, relates to the slope facings. 
The second relates to the division embankment and the drainage arrange- 
ments. 
Both of these changes are discussed in the annual report of the chief engineer, 
and recommended by the Secretary of the Interior in his report. 
The third change relates to the increase of the capacity of the reservoir. 
With regard to the first proposed change, the original specifications for the 
water facings of this reservoir require that the slopes be covered to a thickness 
of eighteen inches, with small stones (three-inch cubes) beginning one foot above 
the present water level, and ending seven feet below the same. 
By this plan that portion of the bank above the riprap is left unprotected 
from the action of the waves, and the lower portion of the slopes is also left 
without protection. 
The question to be considered is, whether by this means sufficient security is 
afforded to the embankments. 
The requisites of a slope facing are: first, that it should protect the banks 
from washing; second, that it should have sufficient weight to prevent the 
DISTRIBUTING RESERVOIR. WASHINGTON AQUEDUCT. 
41 
saturated earth-bank from sliding inwards in case the water in the reservoir is 
drawn down suddenly ; third, that the materials of which it is composed should 
be sufficiently weighty, and so disposed as to prevent their being displaced by 
the action of the waves. 
A reference to the experience of some other reservoirs will show the necessity 
of extending the facings to the top and bottom of the bank, and making them 
of heavier stones than were called for by the original plan. 
On the reservoirs of the Brooklyn and New York water works, the waves, in 
an ordinary high wind, wash up from ten to fifteen feet on the slopes, frequently 
dashing over the top of the bank. On the 23d of April, 1859, the waves in one 
division of the Ridgewood reservoir, in Brooklyn, twelve acres in area, washed 
to the top of the embankment, a vertical height of nine feet, cutting out the 
earth and gravel between and behind the stones with which the bank was faced, 
and causing many of them to settle backwards from six to eight inches. This 
wall was composed of stones not less than twelve inches in thickness, laid upon 
the earth embankment, with the joints well squared and fitted together, but 
without the backing of broken stone used in the wall now laying at the 
"Drovers' Rest" reservoir. The damage caused by the waves was so great 
that it was necessary to relay a large portion of the wall, and fill all the joints 
with cement and concrete. 
I specify the day above mentioned, as it was the one on which the waves ran 
highest during that season, but like injury was done to the wall every day for 
several weeks, until the water was drawn off and the wall repaired, as stated. 
The original design terminated the wall just above flow-line; after this, how- 
ever, it was carried to the top of the bank and coped. It was about this time 
that the wall on the New Croton reservoir was beginning to be laid. The effect 
produced by the failure of the Ridgewood wall was such, that the plans were 
changed on the Croton reservoir, involving great additional expense. 
These facts show the necessity of extending the slope facing to the top of 
the bank for protection; and as the water will frequently be lowered in the 
reservoir, it is no less essential that it should be carried further down the slopes 
than was originally contemplated. 
The wind, sweeping over the large area, would dash the waves against the 
wall with sufficient force to dislodge such small stones and roll them to the 
bottom; while in winter, the ice, especially when the water was falling, would 
very effectually destroy a riprap wall of " stones broken into cubes of not more 
than three nor less than one and a half inches." 
In September, 1859, the water being drawn rapidly from the Detroit reservoir, 
the saturated earth of the embankments slid forward, carrying with it the water 
facings. 
In December, 18G3, one of the mains of the Jersey City water works having 
burst, the reservoir at Belleville was suddenly emptied, and a like result ensued. 
These reservoirs were lined with brick walls, laid in cement, and supposed 
to be water-tight. They were sufficiently so to prevent the water in the bank 
from running out through them ; but no facing of ordinary cheapness has yet 
been discovered which will prevent water from penetrating the bank to some 
depth. Had these been heavy stone walls, instead of light brick ones, the 
accidents would probably not have occurred. 
While a dry wall, allowing the water to run out more freely, is preferable in 
such a case, any wall at all which is not carried down to the foot of the slopes 
and there well bedded but adds to the danger. 
It is very evident that a riprap facing to the slopes, covered in its turn with 
stones sufficiently large to resist the action of the waves, and so laid as not to be 
affected by the anchor ice, is preferable to a facing of small stones entirely. The 
large stones prevent the small ones from being washed from their places, while 42 
WASHINGTON AQUEDUCT. 
the small ones prevent the earth from being washed from the banks through the 
joints of the large ones, as happened on the Ridgewood reservoir. 
It has been urged, in opposition to this change of plan, that the cost will be 
greater, and that, moreover, it will not be carrying out the original designs of 
the Washington aqueduct, and therefore should not be made on any account- 
that is to say, a plan devised eleven years ago must be adhered to, because it 
was made then, notwithstanding experience has clearly demonstrated, within 
those eleven years, that the plan is faulty in many respects. That economy 
which looks to a diminution of first cost, regardless of future expense in repairs, 
is a very false economy. 
Experience and reason showing that the slopes should be covered from top 
to bottom, I propose further to show that the additional cost of putting on the 
present wall instead of riprap is slight in itself, and very small in proportion to 
the advantages to be gained. 
The price for which A. A. McGaffey agreed in 1858, when labor was cheap, 
to furnish and lay the riprap was $1 50 per cubic yard. It was then expected 
that a considerable portion of the material could be obtained from the excavation 
in the reservoir. Under his contract no work was ever done on the wall. 
In September, 1862, S. L. Rodgers & Co. agreed to furnish and lay the stone 
for $1 70 per cubic yard. These contractors soon found that it was impossible 
for them to do the work at this price, and made repeated applications for an in- 
crease of compensation. 
I am convinced that they could not have laid this work for anything near 
their contract price, and they would have thrown up the contract for this reason, 
had it not been annulled in August, 1863, for their inefficiency and delays in 
the prosecution of the work. Nothing was done by them on the slope wall, 
except the furnishing of a small proportion of the stone. 
The items to be examined in estimating the cost of the riprap work are the 
price of stone in the quarry, cost of quarrying, cost of breaking, cost of carting, 
and cost of spreading stone on the slopes. 
There being no stone in the immediate vicinity of the reservoir suitable for 
this work, it is necessary to procure materials from quarries on the canal bank, 
the nearest of which is about one mile distant from the reservoir, and one 
hundred feet below its level. The least price charged by the owners for stone 
from these quarries is believed to be twelve cents per yard. The stone is of a 
nature difficult to quarry, and the quarries contain much that is unfit for the 
work, and which has to be removed. The cost of quarrying is at the minimum 
one dollar per yard. 
Then the stones must be broken by hand into three inches cubes, costing 
seventy cents per yard. 
A horse, cart, and driver, costing $2, will make ten /rips per day, averag- 
ing half a yard per trip, making the cost of hauling forty cents per yard. The 
stone being dumped on the edge of the bank, two men can adjust twenty yards 
per day, making the cost of spreading fifteen cents per cubic yard. 
We have, therefore, the following as the cost of the riprap facing : 
Price of stone in the quarry, per cubic yard 
Cost of quarrying 
SO 12 
1 00 
Cost of breaking 
70 
Cost of carting 
40 
Cost of spreading 
15 
Total 
2 37 
Add 20 per cent, for superintendence, profits, &c 
47 
Total cost 
2 84 WASHINGTON AQUEDUCT. 
43 
For slope wall, with riprap backing, the cost of the preparation of the stone 
is somewhat less, but that of quarrying and laying the same is increased. The 
cost is as follows : 
Price of stone in the quarry $0 12 
Cost of quarrying 1 25 
Cost of carting 40 
Cost of preparing and laying stone 1 04 
2 81 
Add 20 per cent for superintendence, profits, &c 56 
Total cost 3 37 
The contract price is actually $3 per yard, which, from the above calcula- 
tion, seems by no means to be exorbitant. 
The quantity of slope facing was estimated on October 1, 1862, by the 
then chief engineer at ten thousand yards (under the original plan,) of which 
the cost, estimated at the above prices, would be- 
8,800 cubic yards riprap, at $2 84 per yard $24 992 
1,200 cubic yards slope wall around gate-houses, at $3 per yard. - 3 600 
Total 28 592 
As stated above, it would be necessary to cover the whole slope with stone. 
Supposing the work done in this style, and the contractors allowed the price 
calculated above, which is considered barely a paying one at present prices for 
labor, the cost would be- 
17,000 cubic yards riprap, at $2 84 per yard 48 280 
1,400 cubic yards slope wall, at $3 per yard 4 200 
Total 52 480 
The cost of the slope wall, as building under the present contract, 
will be, 20,300 cubic yards, at $3 per yard 60 900 
An increase of $8 420 
By no means a large amount when we consider the great superiority of the 
plan involving the greater cost. The quantity of wall is greater than that 
estimated for the riprap, it being made heavier on the more exposed portions of 
the embankment. 
With respect to the above estimate of cost of riprap, it must be borne in mind 
that prices both of labor and materials have advanced fully fifty per cent, since 
July, 1862, when S. L. Rogers & Co. made their bid. 
The second change in plan requires some explanation also. 
The theory of the reservoir, as planned by Captain Meigs, is this : The water 
will be introduced at one end, fill the west basin, and there having time and 
space to settle, will How in a thin sheet of pure water over the division embank- 
ment, left forthat purpose, a little below the ordinary flow-line, and be drawn to 
the city from the other end of the eastern division. Communication between 
the two basins is had by a culvert through the division bank about twenty-five 
feet below flow-line. This culvert to be closed ordinarily by a stop-cock. 
If ever the water in the receiving reservoir falls to the level of 144 feet above 
the datum line, this overfall will cease to work. If ever it is found advisable 
to reduce the pressure on the conduit, as the overfall requires a head on the 
conduit of at least two and a half feet, the same will be the effect. In such 44 
WASHINGTON AQUEDUCT. 
case, instead of passing pure water to the eastern division, we must open the 
culvert and pass the lowest and, therefore, most impure water. Practically, this 
will be the case nine-tenths of the time. The daily supply to the city will in a 
few years reach thirty millions of gallons. In this case the upper basin will 
hold only three days' supply, and the water from the aqueduct coming in at the 
bottom of the reservoir, will tend to keep the lower stratum of water in continual 
agitation, and prevent the deposit of sediment called for by the plan. When 
passed through the culvert, it will probably reach the second basin in a worse 
state than it entered the first. 
With the present arrangements at the effluent gate-house, it is impossible to 
draw surface water to the city, and at the same time to waste any of the impure 
water at the bottom of the reservoir. The supply of surface water to the pipes 
is regulated by stop-plank ; the drain pipes being on a level with and close to 
the service pipes, the stop-plank must all be removed to enable bottom water to 
be drawn off, and this will also allow it to enter the service pipes. 
The advantage of having an arrangement for separate drainage and supply is 
obvious. The experience of other cities affords many examples of it, of which 
one may be here cited. 
In Albany, during the summers of 1854 and. 1855, the water was very impure 
and offensive. The construction of the gate-house at the reservoir was such that 
all the supply to the city was drawn from the bottom. Investigation showed 
that at the reservoir " the water taken from the surface emitted no odor, and 
tasted sweet, but on going to the waste-weir, through which the water taken from 
the bottom of the reservoir was flowing, a most nauseous odor revealed itself." 
The stop-plank arrangement for regulating the supply is, at the best, an awkward 
and inconvenient one. 
Besides, the present plan gives no separate drainage to the western division 
of the reservoir. If from any cause the water there should become very impure, 
while that in the eastern was still serviceable, or if there should be a leak making 
it necessary to draw off the water, the eastern division would also be necessarily 
emptied, causing a great loss of water and of time. The original plan of Captain 
Meigs contemplated a separate drainage into the canal from this basin. It is 
unfortunate that this idea was abandoned. 
In considering the improvements which might be made on this reservoir, the 
plan suggested by the shape of the reservoir and the natural conformation of the 
surrounding ground would be, to have the influent gate-house at the north, and 
the effluent at the south end of the division bank, with separate inlets to each 
division, and an independent drain from each leading directly to the canal, while 
the service pipes would also run directly down the hill to the river road, and 
along that to the city. But as the gate-houses are already partly built, this can- 
not now be done, so the best adaptation must be made of the existing structures. 
The fact that the central drainage trench projected in the original plan has been 
partially excavated makes it cheaper to avail ourselves of it. We wish to secure 
a separate discharge from the western division at any level, an overfall commu- 
nication between the two basins, an independent discharge at any level from the 
eastern basin, aud separate drainage from each basin. 
To accomplish these objects it is proposed to carry up the division bank to 
the height of the other banks, and build in its centre a gate-house having an inlet 
to the western division, an overfall for the surface water to pass to the eastern 
division, and four gate openings-one leading to the eastern division at a lower 
level, and the other three for drawing service or drainage water from various 
heights into a central well or bay, whence a culvert will lead to the effluent pipe- 
vault, where by an arrangement of stop-cocks the water can be turned either to 
the city, or into the drain channel. 
A wall with gate openings at various heights should also be constructed in 
the effluent gate-house, which can easily be done. All of which is estimated to 
cost less than $30,000, with an incalculable gain to the city in the purity of the WASHINGTON AQUEDUCT. 
45 
water, ajjd the advantageous arrangements for drawing. The working of this 
arrangement is so very lucidly explained in the annual report of the chief en- 
gineer, (page 6,) that it is needless to dwell longer on it. 
The third proposed change appears fully as important as the others. It con- 
sists in deepening the reservoir, so as to give greater storage capacity. It is 
proposed to excavate the bottom to a depth of twenty-four feet below flow-line, 
or thirteen feet below the present bottom. The lower slopes to be paved with a 
rough wall, where the slope wall is already built, a berm ten feet wide to be left 
at the base. This will give an additional capacity of 149.050,000 gallons, making 
the whole capacity 299,900,000 gallons. This will require about 460,000 cubic 
yards of excavation, and 15,000 cubic yards of slope wall, and is estimated to 
cost $223,100 in addition to the cost on the present plan. 
While the capacity is thus greatly increased, an object greatly to be de- 
sired, and one much sought after now by all the large cities, (New York 
has just completed a reservoir holding 944,000,000 gallons,) I do not 
consider this as the chief benefit to be derived from the change. I have 
already mentioned the probability that the flow-line will in practice be ne- 
cessarily lowered from 146 feet above datum. I must again speak of it in 
this connection, as I consider the subject a very important one. At the influent 
gate-house, the bottom of the conduit is two feet below the ordinary bottom of 
the reservoir; the crown of the arch is therefore four feet below the assumed 
flow-line. Experience goes to show that a masonry conduit like this one can- 
not be safely trusted to bear such pressure. On the Croton aqueduct, which is 
as well constructed as any in the country, and has stood for twenty years, it has 
been considered dangerous for several years to put a head of water on th6 crown 
of the arch. Whenever it is done, leaks break out in fresh places. 
The danger arises, not from the upward pressure, tending to lift the arch, but 
from the lateral pressure, which tends to split the conduit longitudinally, open- 
ing cracks at the top and bottom. No difficulty is to be apprehended where the 
masonry is below the natural surface of the ground, but only in embankments, 
where the weight of the superincumbent earth may not be sufficient to hold the 
masonry together in certain contingencies. 
The Croton aqueduct is of the section 
shown in Fig. 1. Of this the assistant 
engineer says : " The stone masonry 
outside of the brick-work was intended 
to be strong enough to resist the pressure 
of the water without the weight of the 
outside bank; but it doesnot prove to be 
so. The consequence is, that when a 
rain and thaw loosen the earth of the 
bank, and a sharp frost shrinks the bank, 
taking the weight from the masonry, it 
causes cracks, if the water stands more 
than three inches above the spring-line 
of the arch." 
The section of the Boston aqueduct is shown in Fig. 2. 
Of late years it has been run under a head. The engineer, 
in his report for 1863, says : " The difficulty resulting from 
cracks in the brick aqueduct is a serious one, and from 
the additional duty imposed on the aqueduct by using it as 
a pipe, under a head, is liable to increase with the increase 
in the consumption of water, unless measures are taken to 
strengthen those portions of the aqueduct resting upon 
embankments by concrete foundations and backing of the 
same material as high as the top of the invert." 
Fig. 1. 
Ew- 2. 46 
WASHINGTON AQUEDUCT 
The section of the Washington aqueduct 
is shown in Fig. 3. The masonry not being 
sufficient to withstand the thrust of the water 
without support from the bank, any shrinkage 
relieving the pressure of the earth will cause 
the ring io open at top and bottom when full 
of water. This has already occurred in 
some instances. 
For size and form this conduit is as yet an experiment. While able, accord- 
ing to calculation, to bear much more pressure, some slight defect in materials 
or workmanship, not to be guarded against even by the careful supervision and 
inspection exercised over the construction of this work, may destroy the value 
of some portion of the conduit. The fact that cracks have already occurred, 
goes to prove the soundness of this opinion, and to show that we will not always 
be able to carry the proposed height of water in the reservoir. 
Suppose, then, that the water must be drawn down to the level of the crown 
of the arch. This will reduce the depth of water in a large portion of the 
reservoir to seven feet. This depth is not sufficient to insure purity of water, 
especially in this latitude, where the heat of the summer sun is so intense. 
Shallow reservoirs are condemned by engineers in this country and abroad. 
An eminent English engineer says : " If shallow reservoirs are exposed to the 
heat of the sun in summer, they give rise to vegetable and animal life." An- 
other says : " I do not know exactly what depth is required in a reservoir to 
prevent vegetation. I have known considerable vegetation in ten feet water." 
The engineer of the Philadelphia water works, in his report for January, 1859, 
says : " By raising the banks of the Kensington reservoir seven feet, sufficient 
additional depth would be obtained to add materially to the purity of the water. 
Much of the difficulty here has been on account of the want of depth of water 
in the reservoir." The depth of this reservoir was fourteen feet. 
The same engineer, in his report for 1860, speaking of the subsiding reservoir 
for the 24th ward works, says: " The depth of water is of the greatest im- 
portance in purifying by subsidence;" and recommends the construction of ad- 
ditional subsiding reservoirs. In his report for 1862 he says of the Fairmount 
reservoirs, that " when full, they only contain fourteen feet of water, a depth 
insufficient in our climate," and recommends an increase of depth. The water 
in the Corinthian avenue reservoir, twenty-seven feet deep, he says is better than 
that in any of the others. " On account of its greater depth and capacity, th 
water has time to deposit many of its i mpurities, and to decompose others, as 
well as escapes that degree of overheating in the sun's rays which encourages 
the growth of confervas and animalcules, and the putrescent decomposition of 
organic matter." 
The chief engineer of the Jersey City water works, in his report for 1856, 
says: " The advantage of keeping a large supply of water in the distributing 
reservoir is seen in the improved quality of the water by being allowed to 
stand for a considerable length of time before it is used. There is a marked 
difference between the appearance of the water when it is used in the city almost 
as soon as it is pumped, and as it appears after being allowed to settle for 
Fig. 3. WASHINGTON AQUEDUCT. 
47 
several days in the reservoir before distribution." Similar remarks are found 
scattered through the reports of water-works engineers all over the country, to 
quote which would require more space than can here be given. I have merely 
made these few extracts at random to show the great importance attached to 
the subject by others. 
With the supposed reduction of depth in this reservoir, the opportunities for 
deposition of sediment are certainly diminished, the water being kept in more 
rapid motion, as the quantity in transitu bears a larger proportion to the whole 
mass. At this level the reservoir will contain ninety-four and one-half million 
gallons, a small quantity for storage. 
I have said before that increased storage capacity is sought in all the large 
cities. The report of the water-works engineers all over the country abound 
with complaints of deficiency in this respect, and recommend the construction 
of larger reservoirs. Large sums of money are annually expended for that pur- 
pose, much of which might have been saved by the adoption of proper measures 
in the first place. The reservoir at "Drovers' Rest" is now in better condition 
for making such improvements than it ever will be again. The gate-houses re- 
quire but little alteration, the pipes, as before stated, being below the proposed 
new grade of the bottom ; and the surplus material dan be more advantageously 
disposed of now than at any future time. 
It is difficult to understand why it should have been originally designed to be 
so shallow, except from motives of economy. For the reasons given above, it 
appears that it would be very mistaken economy to build it so. 
In the estimates of the cost of the completion of the Washing- 
ton aqueduct, submitted to the Secretary of the Interior by the 
late chief engineer, in 1862, the item for the distrib.uting reser- 
voir is $30,499 
In the estimate submitted by the present chief engineer, in 1863, 
the corresponding item is 87,720 
Increase of estimated cost .... 57,221 
To which add amount paid for said work from October 1, 1862, to 
October 1, 1863 28,534 
Total increase of estimated cost 85,755 
So very remarkable a discrepancy requires an explanation. 
A portion of the difference arises from the change of plan for slope facings. 
In 1862, the estimate provided for 8,800 cubic yards rip rap at $1 70 14,960 
" " " 1,200 cubic yards slope wall, at $3 3,600 
Total 18,560 
The estimate of 1863 was for 20,300 cubic yards wall, at $3. 60,900 
Increase 42,340 
This leaves still for the earthwork, &c., a difference of $43,415. 
When the work on the reservoir was resumed in 1862, cross-sections were 
taken of the embankments, and the quantity requisite to finish them was taken 
as the basis of the estimate of work to be done. The bottom, whence the 
material was to come, was not cross-sectioned, and, consequently, neither en- 
gineers nor contractors knew how much was to be taken out. 48 
WASHINGTON AQUEDUCT. 
The estimate of 1862 called for cubic yards excavation 26,200 
When the present chief engineer took charge in July, 1863, the 
bottom was carefully cross-sectioned, and it was found that the 
amount of excavation required to comply with the specification, 
wasc. y. 66,200 
Add excavation done, Oct. 1, 1862, to Oct. 1, 1863 . .c. y. 64,509 
Total which was to have been done October 1, 1862c. y. 130,709 
Under estimated October 1, 1862 c. y. 104,509 
This shows that the above increase of 843,415 in the estimate of the cost of 
the reservoir earthwork is not due to any change of plan, or alteration in the 
actual quantity of work to be done. 
All of which is respectfully submitted. 
J. J. R. CROES, 
Principal Assistant Engineer IF. A. 
Silas Seymour, Esq., 
Chief Engineer and General Superintendent, W. A. 
II. 
In the effluent' screen well at the distributing reservoir are laid four 48- 
inch mouth-pieces for the supply of the city. Of these, one is now furnished 
with a 12-inch discharge, for draining the reservoir; another is capped in the 
pipe-vault; a third is reduced to 30 inches in the vault; and the fourth to 12 
inches. 
At the end of the seven-feet conduit around the reservoir is the auxiliary 
gate-house, in which is a 48-inch mouth-piece. The pipe on leaving the gate- 
house is reduced to 30 inches, and leads to the pipe-vault, a distance of about 
one hundred and fifty feet, where it is connected by vertical pipes with the 30- 
inch and 12-inch pipes above mentioned. 
In the vault are four stop-cocks, viz: 
One 48-inch ; closing connection between reservoir and 30-inch main. 
One 30-inch; closing connection bet ween auxiliary gate-house and 30-inch main. 
One 12-int h; closing connection between auxiliary gate-house and 12-inch main. 
One 12-inch; closing connection between reservoir and 12-inch main. 
Leaving the vault, the 12-inch and 30-inch mains run parallel about three 
thousand three hundred feet across the country to Foundry branch, where is a 
chamber containing a blow-off pipe from each main of its own size, and a 12-inch 
connecting pipe betweeen the two mains. There are here two 30-inch and 
three 12-iuch stop-cocks, so arranged that the portion of either main between 
the reservoir and this point can be emptied, while the portion below is supplied 
from the other main. Three hundred feet east of tliis chamber is the lowest 
point outside of the city on the pipe line. The pipe is here only fifteen feet 
above the datum line, making a fall of one hundred and fifteen feet from the 
vault at the reservoir. From here the mains follow the road along the canal 
f >r about one thousand feet to College pond, which is crossed by an arch of one 
hundred and twenty feet span, composed of two 30-inch pipes. From here the 30- 
inch ami 12-inch mains are continued along the river road and Bridge street, in 
Georgetown, about five thousand two hundred feet, to Rock creek, where both 
are enlarged to 48 inches diameter, and form an arch of two hundred feet span 
WASHINGTON AQUEDUCT.-MAINS LAID BY THE UNITED STATES. WASHINGTON AQUEDUCT. 
49 
across the creek. In the west abutment of this bridge is a duplex water en- 
gine, which forces water through Green, West, and High streets, to the high- 
service reservoir, on the corner of High and Road streets. The force main is 
12 inches diameter for fifteen hundred and fifty feet, and is then reduced to 10 
inches for three thousand five hundred and thirty-eight feet. The water surface 
in the reservoir, when full, will be two hundred and twenty-five feet above the 
datum line. 
At the east end of the Rock Creek bridge the pipes are again reduced respect- 
ively to 30 inches and 12 inches. The 30-inch main follows Pennsylvania av- 
enue to the circle, then deflects to the left and passes through "K" street, Massa- 
chusetts avenue, and New Jersey avenue to "B" street north, where it runs east- 
wardly for one hundred and two feet, terminating in a dead end; a distance in 
all of about fifteen thousand feet. The 12-inch main, starting from Rock creek, 
follows the line of Pennsylvania avenue and Eighth street east to the navy 
yard wharf. It passes around the Capitol square by " A " street north and First 
street east. Total length about twenty-four thousand four hundred and ten feet 
From the corner of "B" street north and New Jersey avenue, a 20-inch main 
runs through the reservation, (connecting at Pennsylvania avenue with the 12-inch 
main, Maine avenue and "B" street south,) to a point opposite the south door 
of the Smithsonian Institute. Length five thousand one hundred and thirty-seven 
feet. 
The branches from the 20-inch main are- 
1st. A 12-inch pipe down Four-and-a-half street, seven thousand eight hun- 
dred and seven feet long. At the penitentiary gate this is reduced to an 8-in ch 
pipe, which runs two thousand and forty-seven feet to the United States arsenal. 
2d. A 12-inch pipe, nine hundred and thirty-eight feet long, to the fountain in 
the Smithsonian grounds. 
3d. A 6-inch pipe, three hundred and forty feet long, to the south door of the 
Smithsonian building. 
From the 30-inch main branches a 12-inch pipe at Twenty-fourth street, which 
runs down that street two thousand five hundred and sixty-seven feet to the 
Observatory gate, is there reduced to a 4-inch pipe, which runs six hundred and 
eighty-nine feet through the Observatory grounds, and, again reduced to two 
inches, runs one hundred and forty-two feet further. 
The branches from the 12-inch main are- 
1st. A 4-inch pipe at Seventeenth street, leading to the fountain in the Presi- 
dent's grounds, nine hundred and eighty-six feet. This, reduced to two inches, 
then runs one hundred and one feet further. 
2d. At Eighth street west, a 12-inch pipe runs up Eighth street, down F 
and up Seventh streets, for two thousand four hundred and seven feet, supplying 
the Post Office and Patent Office. This, reduced to ten inches, runs up Seventh 
street nine hundred and eighty-seven feet. 
3d. A 12-inch pipe up Four-and-a-half street to Judiciary square, one thou- 
sand one hundred feet. 
4th. At foot of Capitol hill, a 12-inch pipe to the fountain in the square, 
two hundred and forty-nine feet. 
5th. In A street north and New Jersey avenue, a 12-inch pipe, three hundred 
and fifty nine feet long, connects with the 30-inch main in B street. 
Besidt s the stop-cocks on branch pipes at all intersections, there are on the 
30-inch main stop-cocks at each end of the Rock Creek bridge, andon K street, 
near Th .'teenth, opposite the square. 
On 12-inch main, there are cocks at Twenty-first street, Eighth street, New 
Jersey avenue, corner of A and First streets, and navy yard wharf. 
On the Patent Office branch, there is a stop-cock on the corner of F and. 
Eighth streets. 
Mis. Doc. 83 4 50 
WASHINGTON AQUEDUCT. 
Summary of lengths of mains laid by government, with branch lines. 
- 
2". 
4". 
6". 
8". 
10". 
12". 
20". 
30". 
48". 
Pipe vault to College pond 
4,597 
4,597 
Across College pond, double 
5,131. 9 
> 375.4 
To Bridge 6 
5,131.9 
Across Bridge 6, double ..... 
1, 634 
281.6 
551.2 
To the Circle 
1,634 
...... 
To navy yard, by Pennsylvania avenue 
22, 774 
To B st., by K st. and N. Jersey avenue 
5,137 
13, 627 
From B street north to B street south.. 
2,047 
7, 807 
Down 41 street to U. S. arsenal 
1 
To Smithsonian fountain 
340 
938 
To door of Smithsonian Institute 
38 
Connection 20" and 12", Pennsylv'a av 
24th street, from Pennsylvania avenue 
to Observatory gate 
142 
2, 567 
In Observatory grounds 
689 
17th street and President's grounds 
101 
986 
987 
2, 407 
To Post Office and Patent Office 
From B to A streets north 
359 
4| street, from Pennsylvania avenue to 
Judiciary square 
1,100 
Branch to Capitol fountain 
249 
In Georgetown: 
1st. From pump. Bridge 6, to Green st.. 
3,538 
1, 550 * 
2d. To 7th and High streets 
342 
3d. To centre of reservoir. 
Total feet 
243 
1,675 
340 
2,047 
4, 525 
51, 493. 9 
5,137 
25, 646. 9 
551.2 
Total miles 
0.046 
0.317 
0. 064 
0.387 
0.857 
9. 752 
0.973 
4.857 
0.104 
Total pipe laid by United States 
' 17. 357 miles.