C /3 U52 
 
61sT Congress, [ HOUSE OF REPRESENTATIVES. \ Document 
 
 3d Session. \ [ No. 1329. 
 
 PRESERVATION AND REPAIR OF CABIN JOHN BRIDGE. 
 
 F 189 
 
 .C13 
 
 U52 LETTER 
 
 Copy 1 
 
 FROM 
 
 THE ACTING SECKETARY OF THE TREASURY, 
 
 TRAXSMITTIN(; 
 
 A COPY OF A COMMUNICATION FROM THE BOARD OF COMMIS- 
 SIONERS OF TKE DISTRICT OF COLUMBIA SUBMITTING AN 
 ESTIMATE OF APPROPRIATION FOR AQUEDUCT AT CABIN JOHN 
 BRIDGE. 
 
 January 30, 1911. — Referred to the Coininittee on Apprnpriatiorif: and ordered to Ije 
 
 printed, with ilhistratioiis. 
 
 Treasury Depart.^iext, 
 
 JanMan/ 28, 1911. 
 Sir: I lia\e the honor to trunsmit herewith, for the eonsideration of 
 Congress, copy of a conininnication of the president of the Board of 
 Commissioners of the District of Columbia, of this date, submitting 
 an urgent estimsite of appropriation recommended by the Chief of 
 Engineers, United States Army, and transmitted through the Secre- 
 tary of War, re([iured for the \\^islungton Aqueduct for the preserva- 
 tion and repair of Cabin John Bridge, ^35.000. of which the sum of 
 $lH),00(» is to be inmiediatidy avaihible. 
 
 It appears that extensive leakage has developed at Cabin John 
 Bridge, which carries the Washington A(iueduct across a deep ravine, 
 and that the condition is serious, which explains the necessity of sub- 
 mitting this estimate at this time. 
 
 Respectfully, C. D. Hilles, 
 
 ^•1 ct 111 (J Sevi'ttary. 
 The Speakku of the House of Rkpresentatives. 
 
 Office Commissioners of tup: 
 
 District of Columbia. 
 W<(shuigto)u Jan vary .AV, 101] . 
 Sir: The Commissioners of tlie Disti'ict of Columbia iiave the honoi' 
 to transmit herewith a sup))lemental estimate of ai)propriation needed 
 for the Washino-ton Atuieduct for th(^ liscal vcar to (md June oO. \\)V1. 
 
^ I'KKSKKVATK.N AND KKI'AIK ..K CAHIN ..,.11N HKII)(;k. 
 
 <..• am;';:i';u;?:;"to';;;j;"n^ •'"''i^ '^'•■*^^? -i-ii"^'i.e installation 
 
 ;;;::::;s;:;;^fna^r^---^ 
 
 1..Hos(mI with this cstinrnt. i. th.> h-tter of th. connnissionrrs datod 
 - tl msta„t. tnu.sni.ttmo- it to tho PresichM.t of (ho rnit.MrStato 
 (.1 Ins a fon as per your letter of i.istruHion of th. -^Nt ul i u> u d 
 hcaiino- tho Presidout's approval. " ninino. .md 
 
 s app 
 \ (TV rospectfiillv. 
 
 HOAKI) OK roMMISSH.NKUS. DisTlM. I OK (<„,i:Mr..A, 
 
 l>.\ ( I No II. K'i;i)oi,i>ii. 
 
 lion. Fk'anki.tn Mr\'KA(iii, 
 
 Sr,r,i((rij of //tr 'I'l'iiisni'tl. 
 
 ■mw .>(J, in.. Ihi th,- ( <niimissn>,„'rs uj llir DIslrirt nf Cnhniihiu. ■ 
 
 IIISTHKT OK (OLTMlilA. 
 
 W ;isliiii^r(,,ii AijiK'diict: 
 
 Fur tJ.e preseryatio.. and repair of Cabin .lohn Bri.I-.., in,-lu,iin.. th,> 
 '-•: :',;?';'" « ^^ '"f ' ""'".- ^" i'>-'"vent l<.aka.e in the r H' • 
 
 \ 1.1. nj,t(.n A.,ne.n.t passu,,, tluon^h the l.H<li,e, of uhirh S2( ( i 
 ^hall he nnmediately availahle (snl.nutte.i. VoL 20, p. ]()4, see 'i) s;^.",, (,„o 
 XoTK.-8ee accouipanyinu lettrr ,.f (ransniittal ainl its inciosurcs. 
 
 I AM- \l;v 2(>, l!»l i. 
 
 ('(NO H. Rii)()i,i>n, 
 
 •lollX A. .JOHNSTON, 
 
 \y . y . jiosox, 
 
 Coiiniiis.'iioii,,:'^ of th,' Di.^/rirt of (),lin,il,hi 
 
 I'mtki) Statics Encinioki; Oikki:. 
 
 !>i^o Skvf.ntekxtii Stimoet N\\'.. 
 
 ]\(i.s/n',,<jf,>ii, /}. C. JiUnHin/ Jl, V.ni 
 Mk. I have (he honor tosul.init the followino- item for\raMsmissioM 
 Mirough the re.i(ular channels to the proper comniittce of Conoress for 
 insertion as an amendment t(, the District appropriatio., hiirfor the 
 hs<.al y''=i'- l!»l^, which IS und(M-stood to have been ivported from the 
 committee to the House oi Representatives on -lanuarv IS l:»ll ,),• for 
 |)assao-(> as a sju'cial bill or joint resolution: 
 
 2. Cabin John P>rid,oe is one of the noted cnoi„.>erino- structure^ 
 bcin.^. until ]!»()2. the lon-est cut-stone masonrv aicJi" s,)an in the 
 world It was .•ompleted in ksc:}. since which date it has served to 
 carry t.(>, water supply of the city comino- from the (livut Falls of 
 the 1 otomac, across th(« deep ravin(^, at Cabin John Run. about M 
 tniK's Irom the District line. The a(|uedm-t at this point is one of the 
 weakest points in the system, as an interruption bv the breakino- of 
 the conduit at this brido-e would be verv ditiicult to repair in the short 
 time p(M-nntted l)y the limit(Ml stora.ov supply of wat(M-. The prcserva- 
 
PRKSERVATTOX AND KKI'AIK (>K (WHIN .lOHN HRllKiK. 8 
 
 tion, therefore, of Cabin -lolm Bridg-e is esscntiul to the permanence 
 of the water supply of the District, an interruption at this point 
 beino- likely to cause a shortage or a failure of the supi)ly in the city. 
 
 3. U'hen the watcn- was first admitted to the conduit" from Great 
 Falls, in 186^, a number of leaks were found in the Cabin .John Biidoe 
 when thei-e was at)Out T feet of water in the conduit, which is 9 feet 
 in diameter. The water was drawn otf. the lower half of the conduit 
 was plastered, and after the water was again admitted to the conduit 
 no leakage was observed, the ilow Wuv l)eino- Ixdow (he upper limits of 
 the plastered section. 
 
 4. As the consum])tion of \\at<M- in the city has increased, i-etpiiring 
 the extension and raising of the (him at Great Falls, the conduit has 
 been running fuller until the comj)letion of the dam at Great Falls to 
 its present elevation caused the hydraulic gradient at ("abin -lohn 
 Bridge to be altout 2 feet ab()\ c the ciown of the conduit when the 
 Dalecarlia reservoii- was full. The u])per portion of the conduit 
 through the bi'idge not having been phisteied. it was notiul in JIM).") 
 that th(^ water had worn away th(^ mortar betweim the bricks to a 
 depth in some places of an inch or more. 
 
 5. As the amount of water passing through tiuM-onihiit increasinl. 
 causing a greater depth in the conduit over tlu» l)ridge, the leakage in 
 the bridge began again, and in liM),> the interior was carefully cleaned 
 and ail visible cracks were Hlled with cement moi'tar. The anmial 
 report of the otiicer in charge, for the tiscal year iDOtJ, rei)orts that 
 about 90 per cent of the leakage was stopped by this pjastiu-ing. 
 
 t). Fxperiments were started at this time to det<M'mine the l)est 
 means to remedy the defects. Believing that nuich of the leakage 
 through the bridge occurred through the mortar joints of the brick in 
 the unplastered upper portion of the conduit, the plastering of this 
 part of the conduit in the bi'idge was commenced in the tiscal vear 
 1908. At the end of the tiscal year 1909, i:i4 feet of the :)T0 feet of 
 the conduit through the bridge was completely plastcMvd with Portland 
 cement mortar. As this did not noticeably atl'ect the leakage, etforts 
 were made to push the work of plastering to completion. This work 
 was completetl late in the tiscal year 191<». and ap])eared to stop the 
 leakage at the middle of the bridge, but did not materially affect the 
 leakage between the middle of the bridge and the abutments. 
 
 7. During inspections long cracks in the masonry of the conduit 
 within the bridge were noted on both sides of the center of the bridge, 
 the axis of the bridge lying almost due east and west. These cracks 
 weie kept carefully tilled with cement mortar, and it was not until the 
 conduit through the bridge was completely plastered that those in 
 charge of the a(iueduct felt assured that most of the leakage did not 
 come through the mortar joints of the brick crown of tlie conduit. 
 These long cracks lie in the lower (|uadrant of the conduit on the north 
 side of the l)ridge. and undoul)t<Mlly ha\e been caused by the une(|uai 
 expansion of the two sides of the bridge, the south side l)eing exposed 
 throughout the day in the sununer to the direct rays of the sun. while 
 the north side of the bridge is nearly always in the shade. This un 
 e((ual ex{)ansion h:is broken the brick rings of the conduit along the 
 length of the cracks, and the ui)per (|uadrant of the ring is moving 
 over the lower ([uadrant at the rate of one-eighth of an inch a ye;ir. 
 as determined by recent measurements. If tins action is permitted to 
 s-o on it is tikelv that the rate of this movement will be accelerated 
 
I'RKSKI{VA rio.N AM) IJKI'AIli <»K CAI'.IN -loHN liRllXJi:. 
 
 Ciicli ycjir uiilil llic tiiial t'liilin'c ol' (lie ((jiiduit In (•()lla])se. A> the 
 iiiitsomv in the brido'c contracts duriiij^- cold wcatlKT the cracks in tlio 
 conduit i)])(Mi. t lie extent of I lie opcninii' depending:' to sonic extent upon 
 the dej^Tee ot' cold. 
 
 s. In the sununer. under pcesent conditions, the water leaks through 
 the joint> in the niasoni'v >i(ie walls of the hridoc ;ind passes down 
 ov'ei' the i'ace of the hi'idy'e to the ^^round l)(do\\. In the winter, the 
 watef ri'ee/ino- to some extent in the joints ol" the niasoni-y on the out- 
 side of the l)i-i(|o-e. much of the leakaji'c i)ass(vs down the insiih' of tiie 
 Itridue I hrouoh the hoHow abut ments and thence through the dooi'- 
 ways in the side walls of the ahutments. (See photoo-raph appended.) 
 The condition of the extei'ior of the l>i'ido-e i< shown in the photo 
 i4"i'aphs appended hei'clo. taken on I )ecend)er 2i\ iH|i>. which indicate 
 to some extent the leaka^^e from the l»iidu(« diirine- the cold weatluM' 
 of the ndddle of i)ccend>er. It lia> Ikmmi t'stimated that the leakaLi'e <d' 
 water through the masonry of the l)iido-e at the latter date was not 
 less than I'.OOd.tMiO t^-allons of \\atei' per day. The maximum ca))acity 
 of the conduit is IKi.dOd.dOd gallons per day and the axerau'e annual 
 corismnption is alK)ut <>i!,<iO(i,(i(i(> o-allons ])er day. 
 
 ;». It isl)(die\cd thai the condit ioti is so sei'ious that the application 
 of the neces>ar\ reme(ly should he no louLj'er |)Ostponed. At the time 
 of the suiimissidii of th(^ estimates in the annual re|)ort fi'oni this 
 ollice il was i-eali/.t'd that ixM'manent repairs would soon he necessary, 
 hut estimate^- were not (hen sul)mitted because the manner of repair 
 ine the liridiif in the most economical and jn'riuanent mannei' liad not 
 then heen delcmuned. It is now proposed to place within the hridoc 
 a metal lininj^- eil her of a steel or iron tube S fei't ('■> inches in diameter, 
 sunounded l>y conei'ete. or l»y the })lacinL;of cast-iron sectional lining'. 
 N feet in diameter, similai' to that used in the W'ashinn'ton .\(|ueduct 
 tunnel under Ivock ('reek. I'jiher method would l)e satisfactory and 
 would ri'iiderthe l)ri(l^-e water tiu'ht. thus pre\ cut ini;- t h(> disinteui'a 
 tion of the nia>onry in the face of the hri'ly-e, caused hv the free/in^' 
 of ihe wat(M- in the joints and interst ice->. and would check the deteri- 
 oration of the conduit now in proui'cs^. 'Vho j)lan ado|)ted would de- 
 pend up(m the prictvs received for furnishine' th(> materials necessai'y 
 undei' the two methods, and also upon the conxcnience of instadation 
 with the least interruption to the water su|)ply. 
 
 !". iJeducine- tlie diameter of the MU^ feet of conduit throueh the 
 liriilet' to s feet I'l inches. oi- to ^ i'(H^t. would tend to increase* the los> 
 of head at maxinnun rate of How <>.7 inch, or l.i' inches, respect i\'tdy. 
 The ^toppniLi' of the leakae'e would tend to I'cduce tin* loss of luMd 
 about ! inches. Thei'id'ore. the linal etl'cct of I'cpairs to the bridec 
 would be to reduce (he loss of head by about .'i.:! inches for a diameter 
 of S feet il in:he>.. or about l'.s inches \\<v a iliamet(M' oi' s feet, at the 
 maxinmm rate <d' flow in the conduit. The total loss of head between 
 (ireat !''alU ;ind Halecarlia Keservoir. at maximum rate of llow. i^ 
 about 7 feet ',» inche>. 
 
 !1. The ne(C->sity for ihi> work is consitlered -^o urecnt that the 
 estimate o\' -Sl.^.doit. as noted at)o\e. is sul»nntted at this time with a 
 \'iew to lia\ine- a portion of the estimat»'d amount made iimueiliatelv 
 a\ail'ible. -o that th(> work may be lieeam at once. 
 \'ei-\ re>peci fully . 
 
 \\ . ('. Lanoi 11 1. 
 
 The ( 'iiii'.i' (»K 1\N(.1M'.K Us. r. S. Akmv. 
 
 ir-/.v/////,//o,,, /). c. 
 
PRESEKVATION AND HKPAIK OF ('AHIN -iniiN URIIX,!;. 
 
 [I'irst )iiilor>eniciU.j 
 
 
 
 A\'ai; I)kpai!t:\iknt. 
 
 Ol'^KlCK OF THK ClllFF OF Kn(;IXKKKs. 
 
 ^y<ls/,|,,</fon. 'J I 111 mini i'^. lUll, 
 
 1. Respectfully siihiiiittod to \\w Secretarv of War. 
 
 '1. The office in cliaro-e of the Washinotoii Aquoduct rcijort^ that 
 extensive leakag^e has developed at Cabin John Hi-ido-e which carries 
 the aqueduct across the deep ravine at Cahin John Knn. Md.. and 
 states his belief that the condition r- serious. '\\w Chiof of Knuineers 
 concurs in this opinion and reo-ards (he riMnedv proposed as of'lii-oent 
 necessity in order to check th(> present h>aka,o-e, nnd aveit the dan»-er 
 of the destruction of the conduit, and \\w c()nse(|uent complete stoppao-e 
 of the water supply of the city of Washington. It is therefore reconi 
 mended that this report and the acconipanvin^- i)hot()o-raphs be trans- 
 niitted to the Commissioners of the District of Columbia, recommend- 
 ing the insertion of an item in the peiuliiio- District of Columbia 
 appropriation bill substantially as follows: 
 
 For the preservation and repair of ('al)in .lolin Hridue, inclndiiiif the in^tal!atioll of 
 a metal lining to prevent leakage intlie portion of the Washington A(|ne(hiet pas-in<>- 
 through the bridge, thirty-live thousand dollars, of wliich Iwentv t!iou<and (h.Hars 
 shall l)e iraniediatelv available 
 
 W. 11. Ih.xp.v. 
 
 ('/I'cf "f hlKJ'lK 'Vs. f^iiifxl S/tlfrS J/V/'//. 
 
 fSi'ciiiKt iii(liirsciin'ii"i.] 
 
 WaI; DEl'AIiTMKXT, 
 
 J<n>iiiini ?.;. 7.97/. 
 Kesi)ectftdly transmitted to the Commissioners of the Distrit-t of 
 C|olumbia, requesting action recommended l)y the Chief of Knoineers. 
 United States Army, in the preceding indorsement. 
 
 J. M. Dickinson . 
 
 S, ii-rtory if ll'/r. 
 
 O 
 
o ^ 
 

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LIBRARY OF CONGRESS 
 
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