THE MUNICIPAL ENGINEERS 
 OF THE CITY OF NEW YORK, 
 
 PROGRESS OF THE CITY TUNNEL OF THE 
 CATSKILL AQUEDUCT 
 
 By Walter E. Spear, M. M. E. N. Y. 
 
 WITH DISCUSSION BY 
 
 SIDNEY W. HOAG, Jr., SAMUEL C. THOMPSON, WILLIAM F. LAASE, 
 LAZARUS WHITE, BERTRAND H. WAIT AND 
 HERBERT M. HALE. 
 
 Reprint from Proceedings, 1012 
 
% 
 
 i:x Hibria 
 
 SEYMOUR DURST 
 
 -■= >: 
 
 When you leave, please leave this book 
 
 Because it has been said 
 "Ever thing comes t' him who waits 
 
 Except a loaned book." 
 
 Avery Architectural and Fine Arts Library 
 Gift of Seymour B. Durst Old York Library 
 
THE MUNICIPAL ENGINEERS 
 OF THE CITY OF NEW YORK 
 
 PROGRESS OF THE CITY TUNNEL OF THE 
 CATSKILL AQUEDUCT 
 
 By Walter E. Spear, M. M. E. N. Y. 
 
 WITH DISCUSSION BY 
 
 SIDNEY W. HOAG, Jr M SAMUEL C. THOMPSON, WILLIAM F. LAASE, 
 LAZARUS WHITE, BERTRAND H. WAIT AND 
 HERBERT M. HALE. 
 
 Reprint from Proceedings, 1012 
 
THE MUNICIPAL ENGINEERS 
 OF THE CITY OF NEW YORK. 
 
 Paper No. 72. 
 
 Presented April 24tii, 1912. 
 
 BGRESS OF THE CITY TUNNEL OF THE 
 CATSKILL AQUEDUCT. 
 
 By Walter E. Spear, M. M. K. N. Y * 
 
 With DISCUSSION by 
 Sidney W. Eoag, Jr., Samuel 0. Thompson, William F. Laasb, 
 Lazari a White, Bertrand H. Wait and 
 Herbert M. Bale. 
 
 After months of surveys and studies by the Board of Water 
 Supply, and after successfully undergoing a careful examination 
 by the Board of Estimate and Apportionment, the City Tunnel, 
 the last important link in the Catskill Aqueduct, was finally 
 authorized and place* 1 under contract last year, and the work i9 
 now well under way. The City Tunnel was not included in the 
 original plan for the delivery of the Catskill supply prepared in 
 1905 by the Board of Water Supply; this plan was of necessity 
 submitted before the problem of the type and location of the Catskill 
 Aqueduct within the City could be properly studied, and provided 
 south of Hill View Reservoir only a single pipe line for the supply 
 of Brooklyn, Queens and Richmond Boroughs, the portions of the 
 City then most in need. Upon investigation it soon became appar- 
 ent that the tentative plan must be materially modified within the 
 City limits in order to economically provide for the delivery of 
 the entire Catskill supply to all portions of the City. Before re- 
 questing a modification of the original plan, the water supply needs 
 of the City and the existing distribution system were carefully 
 studied. The good part of a year was spent in making surveys and 
 
 * Department Engineer. Board of Water Supply. 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 63 
 
 borings in the City to determine the feasibility of the tunnel por- 
 tion of the project, and during the interval between the application 
 for the modification and the final approval of the plan, the boring 
 work was continued to definitely fix the exact alignment and grade 
 of the tunnel. The entire City Aqueduct project, of which the City 
 Tunnel represents the major part, including the proposed trunk 
 mains to be laid in the streets from the terminal shafts of the 
 tunnel in Brooklyn to the Boroughs of Queens and Richmond, was 
 passed upon favorably by the Board of Estimate and Apportionment 
 of two administrations, once on December '10, 1909, and again on 
 July 1, 1910, and w T as finally approved by the State Water Supply 
 Commission on October 20, 1910. 
 
 The City Aqueduct plan thus approved provided for a pressure 
 tunnel, entirely in the solid bed rock underlying the City, on a 
 line nearly 18 miles in length which passes through the center of 
 the Bronx and Manhattan Boroughs and across the East River to 
 the downtown business section of Brooklyn Borough. Much knowl- 
 edge of the geology of this locality was gained in the preliminary 
 work on the City Tunnel, which, with other information, was pre- 
 sented to this Society in February of last year in an interesting 
 paper on the geology of New York City by Dr. Charles P. Berkey, 
 the Consulting Geologist on the City Tunnel project, and Mr. John 
 R. Healy, Assistant Engineer, Board of Water Supply. 
 
 Location of City Aqueduct. 
 
 It will be noted that the line of the City Tunnel, as indicated 
 on Plate 29 begins at the southerly end of Hill View Reservoir, 
 now under construction between Jerome and Mt. Vernon Avenues 
 in the City of Yonkers, and follows in a general way the highest 
 ground through the Boroughs of Bronx and Manhattan. In the 
 Bronx the tunnel is being driven within the ridge of hard gneiss of 
 the Yonkers and Fordham series, lying between the valley of the 
 Bronx River and that of Tibbet's Brook, following a location from 
 Jerome Park Reservoir to the Harlem River close to that of the 
 Old Croton Aqueduct, and crosses under Harlem River in the In- 
 wood limestone, just south of High Bridge. After passing under 
 the Harlem River the tunnel enters the Manhattan schist formation 
 and is laid out under the easterly escarpment of the high ground 
 
6 1 PROGRESS OF CITY TUNNEL OF CATSKIEL AQUEDUCT. 
 
 on the upper west side of Manhattan, beneath High Bridge, St. 
 Nicholas and Morningside Parks and the connecting streets, to Cen- 
 tral Park at 106th Street and Eighth Avenue; thence under Central 
 Park, Sixtli Avenue. Broadway, Fourth Avenue and the Bowery 
 to Delancey Street, still in the Manhattan schist. In Delancey 
 Street near the Bowery the tunnel leaves the schist and passes be- 
 neath the streets of the lower East Side, to the East River near the 
 foot of Clinton Street in a somewhat complicated formation of 
 Inwood limestone and Eordham gneiss. Before reaching the East 
 River the tunnel enters a grano-diorite intrusion in the Fordham 
 series and in this formation crosses under the Fast River to Bridge 
 Street, Brooklyn; thence beneath Bridge Street and Flatbush 
 Avenue to a terminus at Third Avenue and Schermerhorn Street. 
 From the main line in Flatbush Avenue, a branch tunnel is to be 
 driven through Lafayette Street to another terminal shaft in Fort 
 Greene Park. 
 
 The somewhat irregular course of the tunnel in some portions 
 of the City, notably on the lower East Side, is the result of the 
 policy of locating the line beneath public streets and parks and 
 avoiding as far as possible the expense of acquiring easements under 
 private property. Of the 93 870 ft. of the City Tunnel, only 722 
 ft., or three-fourths of 1% of the entire line, is under private prop- 
 erty where easements have had to be purchased, and out of the 24 
 shafts, only 4 had to be located on private lands. A straight line 
 for the tunnel in many localities would have offered some economy 
 in construction, but the experience in acquiring the easements for 
 the pressure tunnel of the new Croton Aqueduct indicated that this 
 economy would have been offset many times by the cost of acquiring 
 rights under private lands. Furthermore, a tunnel in the rock under 
 private property would always be exposed to injury from drill holes 
 for elevator wells and other purposes made by persons ignorant of 
 the location of the tunnel. 
 
 Depth of Tunnel. 
 
 As may be seen in Plate 29, throughout the Borough of the Bronx 
 and in Manhattan from Morningside Park to the Bowery, where 
 sound rock is found at or near the surface, the grade of the tunnel 
 has been fixed at a depth of 200 to 300 ft., which is from 50 to 200 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 
 
 05 
 
66 PB0GBB8S OF I ITV TUNNEL OF CATS KILL AQUEDUCT. 
 
 ft. below sea level; and the southerly portion of the tunnel in Brook- 
 lyn has a depth of but little more than :>00 ft. below the surface. 
 
 At intermediate sections the tunnel has, however, been placed 
 at a much greater depth to secure everywhere a minimum cover of 
 150 ft. of sound rock over the tunnel, this depth being considered 
 necessary to insure finding a sound, tight rock in which to build the 
 tunnel. The first depression made in the grade of the tunnel to 
 reach sound rock is in the section from the Harlem River to Morn- 
 ingside Park. The erosion and decay of the limestone in the Har- 
 lem River made it necessary there to go to a depth of 330 ft. below 
 sea level, and an equal depth was found to be required in the neigh- 
 borhood of 125th Street, where the roek floor is over 200 ft. below 
 the surface in a valley in the bed rock, which is believed to repre- 
 sent faulting of the schist at this point and subsequent disintegra- 
 tion and erosion. Another and deeper depression of the tunnel line 
 was provided at the southerly end of Manhattan Island to carry the 
 tunnel at a safe depth in the solid rock through the lower East Side, 
 where in Hester and Clinton Streets the borings showed that the 
 rock is more or less decayed to a depth of 400 to 500 ft. Under 
 the East River the bed rock is found at a depth of only 80 to 90 ft. 
 below the surface, but slopes off rapidly in Brooklyn to the south and 
 east. The depth of the rock in Brooklyn fixed the distance in these 
 directions to which the tunnel could be built; the depth of wet 
 ground at the end of the main tunnel at Flatbush Avenue and 
 Schermerhorn Street, which was 106 ft., represents about the lim- 
 iting distance through which it is possible to sink a pneumatic 
 
 caisson. ■ • 
 
 General Description of Tunnel. 
 
 The plan for a pressure tunnel in the rock under the City for 
 the delivery of the Catskill supply was adopted because this type of 
 construction was found to be much cheaper than steel or cast-iron 
 mains of equivalent capacity; because the tunnel promised little 
 or no disturbance in the highways and no interference with other 
 uses of the streets; and because the tunnel offered greater certainty 
 of an uninterrupted supply of water at ample pressures in the center 
 of the City's population. 
 
 Of the 24 shafts in the City, spaced on an average about 4 000 
 ft. apart, 22 shafts will be completed as waterways through which 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 67 
 
 Plate 39.— Fig. 1. 
 
 Pi ate 30.- Fig. 2 
 
68 PB0GBE8S OF CITY TLNM.L oi 0AT8KILX AQUEDUCT. 
 
 the entire Catskill supply of 500 million gallons per day may be 
 delivered, by means of suitable connections, to the City's distribution 
 mains; one, Shaft 11 in Morningsido Park, will be a drainage -hail 
 without a waterway; and another, Shaft 1 in Van Cortlandt Park, 
 is a construction shaft and will he plugged and refilled on the com- 
 pletion of the tunnel. Of the 22 waterway shafts, the two terminal 
 shafts in Brooklyn, Shafts 23 and 24, will serve largely to supply 
 the trunk mains 66 in. and 48 in. in size, which are being laid by 
 the Board of Water Supply from these shafts to the Boroughs of 
 Brooklyn, Queens and Richmond and two shafts, Shaft 3, at Jerome 
 Park Reservoir, and Shaft 10 at 135th Street, will have connection 
 of ample size by which to deliver large volumes of water to the 
 Croton system at Jerome Park Reservoir and the 135th Street gate- 
 house respectively. The other waterway -hafts will have connections 
 not exceeding 30-in. in diameter with the nearby distribution mains 
 for the supply of the districts in which they are situated. 
 
 The finished interior diameter of the tunnel will be 15 ft. from 
 Hillview Reservoir to Shaft 10 at 135th Street, a distance of 7.7 
 miles; 14 ft. in diameter from this point to Shaft 17 at Sixth 
 Avenue and 41st Street, a further distance of 5.0 miles; at Shaft 
 17 the diameter will be further decreased to 13 ft. and at Shaft 18 
 at Broadway and 24th Street, 0.9 mile beyond Shaft 17, to 12 ft. 
 This size will be carried to a point 1 500 ft. south of Shaft 20, or 
 about Orchard and Hester Streets, a distance of 2.0 miles. The 
 remainder of the tunnel to Brooklyn, aggregating 2.5 miles, will be 
 11.0 ft. in diameter. 
 
 The general design of the tunnel differs but little except in size 
 from the pressure tunnel constructed on other portions of the 
 Catskill Aqueduct, one of which, the Rondout Siphon, was described 
 to you in May, 1911, by Mr. Lazarus White, who now has charge 
 of the southerly division of the City Tunnel. Typical sections of the 
 15-ft. diameter tunnel, showing the lines to which the rock is to 
 be excavated and the thickness of the concrete lining, are shown 
 on Plate 30, Fig. 1. Generally the type "A" section is being adopted 
 for all sizes of tunnel and the thickness of the lining in shallower 
 portions of the tunnel will not probably be less than 10 in. to the "A" 
 line, and in the deeper sections perhaps 12 to 14. One of the features 
 of the City Tunnel is the Venturi meter which is to be placed in 
 
70 
 
 PROGRESS OF CITY Tl'N'NKL OF CATSKILL AQL'EDl CT. 
 
 the tunnel just above Shaft 2, the first waterway shaft, to measure 
 the entire delivery to the City. The general design of the meter is 
 shown, Plate 30, Fig. 2. 
 
 The City Tunnel differs from ether pressure tunnels of the Cats- 
 kill Aqueduct in the waterway shafts by whieh connections are 
 provided with the distribution mains. Furthermore, with the ex- 
 ception of two section valve Bhafts, L3 and 18, to be hereinafter de- 
 described, all shafts of the City Tunnel are circular instead of 
 rectangular as are most of the shafts in other tunnels of the Cats- 
 kill system where the general American practice was followed. A 
 circular waterway shaft, typical of Shafts 2, 4, 5, G, 7, 9, 12, 14, 
 15, 16, 19 and 22, is shown in Plate 31. The lower portion of 
 the shaft is designed to be lined with concrete, with a finished 
 diameter of 14 ft. from the tunnel to an elevation roughly 100 ft. 
 below the top of sound rock. From this point to the surface or 
 more properly to the bottom of the valve chamber just below the 
 surface at the top of the shaft, a 48-in. concrete-lined steel riser 
 pipe is to be concreted into the shaft. This riser pipe will bo 
 capped by a bronze tee, from which will be taken each way a 
 30-in. connection, to which will be attached two 30-in. valves in 
 tandem, one a service valve, the other a bronze valve attached to 
 the bronze tee which is to be used when the first is being replaced 
 or repaired. At the bottom of this riser pipe there will also be a 
 special valve controlled from the valve chamber or from the surface 
 above the chamber, which is designed to be used only in emergencies 
 to cut off the flow through the riser when the other valves above are 
 out of order. 
 
 The other waterway shafts have two risers, Shafts 3, 8, 10, 13, 
 17, 18 and 20, of the same size as that described, 48 in. in diameter, 
 and the terminal shafts, 23 and 24, 2 risers 72 in. inside diameter. 
 The size of Shafts 23 and 24 are proportionally larger below the 
 risers, being 16 ft. in diameter. The design of one of the terminal 
 shafts, 24, is shown in Plate 32. Each of these terminal shafts has 
 sufficient capacity to deliver the full flow in the 11-ft. tunnel should, 
 by any chance, any accident occur to the other. 
 
 At the so-called section valve shafts, 13 and 18, valves or gates 
 are to be built in the tunnel to permit of cutting off the sections 
 of the tunnel north or south of these shafts. These shafts are 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 71 
 
 Plate 32. 
 
72 I'lax ;i;i;ss of city tunnel of catskill aqueduct. 
 
 roughly rectangular in shape and in addition to a central well 
 giving access to the section valve at tunnel grade, there are to be 
 two risers 48 in. in diameter which are connected to the tunnel either 
 side of the section valve, as shown on Plate 33. 
 
 One of the drainage shafts. Shaft 11, has no riser, as already 
 noted, and i- almosl identical with simijar shafts of the other pres- 
 sure tunnels of the Catskill Aqueduct. This shaft is l<»c;iic<l mi 
 a lateral drift from the main tunnel, about 75 ft. in length, and 
 will be equipped to drain the northerly portion of the tunnel 
 from T Till View Reservoir to Central Park. The other drainage 
 shaft, 21, will he likewise constructed to drain the southerly por- 
 tion of the tunnel, but this shaft has, in addition to the drainage 
 feature, a 48-in. riser through which water may be delivered to the 
 distribution system as at other waterway shafts. 
 
 Capacity of City Tunnel. 
 
 The City Tunnel is designed to carry with a reasonable loss 
 of head the full capacity of the Catskill Aqueduct, 500 mil. 
 gal. per day from Hill View Reservoir, and to distribute this 
 amount as required to the various shafts along the line. With a 
 pressure gradient 295 ft. above sea level at Hill View Reservoir, the 
 tunnel will deliver this amount of water plus an allowance of 
 15% for the period of maximum demand at a pressure in Man- 
 hattan which will never be less than that corresponding to an ele- 
 vation of 260 ft. above sea level and will deliver a supply of 
 250 mil. gal. per day to Brooklyn, at a pressure equivalent to a 
 head of 250 ft. above sea level. 
 
 Contracts for Tunnel. 
 
 The City Tunnel was divided into 4 contracts, as indicated on 
 Plate 29. 
 
 Contract 63 : City line to Burnside and Aqueduct Avenues, 
 University Heights in the Borough of the Bronx, com- 
 prising 21 270 ft. of 15-ft. diameter tunnel and 5 shallow 
 shafts (218 to 246 ft.). 
 
 Contract 65 : University Heights in the Bronx to Central Park 
 at 100th Street, Manhattan Borough, comprising 28 300 
 ft. of tunnel 15 and 14 ft. in diameter and 7 shafts, of 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 73 
 
 Movable roof dads 
 
 Plate 33. 
 
74 PROGRESS OF CITY TUNNEL 01 CATSKILL AQl'KDLXT. 
 
 which 2 are shallow (262 and 278 ft.) and 5 are moderately 
 deep (352 to 478 ft.). 
 
 Contract 66 : Central Park at West 100th Street to Union Square, 
 Broadway and 14th Street, Manhattan Borough, com- 
 prising 23 140 ft. of tunnel, 14, 13 and 12 ft. in diameter 
 and 6 shallow shafts (205 to 253 ft.). 
 
 Contract 67: Union Square, Manhattan Borough, to the terminal 
 shafts in Brooklyn Borough, at Flathush and Third Ave- 
 nues, and at Ft. Greene Park, comprising 21 160 ft. of 
 tunnel 12 and 11 ft. in diameter and 6 shafts of which 2 
 are shallow (318 and 320 ft.) and 4 arc deep (710 to 752 
 ft.). 
 
 Bids were opened on these contracts on May 16, 1911, and awards 
 made to the lowest bidders, as follows: 
 
 Contract. 
 
 Contractor to whom 
 awarded. 
 
 Amount of bid 
 based on engi- 
 neers" estimate < >f 
 quantities. 
 
 Date Of 
 award. 
 
 Date of notice 
 to begin work. 
 
 63 
 
 66.... 
 
 66 
 
 67 
 
 Mason & Hanger Co 
 
 Pittsburg Contracting 
 
 Company 
 
 Grant. Smith & Co.. and 
 
 Locher 
 
 Holbrook. Cabot & Rollins 
 
 Corp.. T. B. Bryson and 
 
 $3 709 372 
 5 590 225 
 
 4 512 605 
 
 5 272 435 
 
 June 1. 1911. 
 June 7, 1911. 
 June 7, 1911. 
 
 June 1. 1911. 
 
 June 9, 1911. 
 June 15, 1911. 
 June 15, 1911 
 
 June 8. 1911. 
 
 You will note that the cost of the tunnel, including the shafts 
 based on the amount of these contracts, gives the following unit cost 
 per linear foot of tunnel : 
 
 Contract 63. .$174. 
 
 65. . 197. 
 
 66. . 195. 
 
 67. . 249. 
 
 These prices are generally higher than those on similar pressure 
 tunnels on the Catskill Aqueduct, which run from $105 to $180 
 per foot and represent not only the additional cost of the compli- 
 cated waterways, the smaller tunnels in the southerly sections, and 
 in the case of Contract 67, the expensive pneumatic caisson work, 
 but also the increased cost and delay in doing work in the City, 
 which will be pointed out later. 
 
PLATE 34. 
 THE MUNICIPAL ENGINEERS 
 OF THE CITY OF NEW YORK. 
 SPEAR ON PROGRESS OF CITY 
 TUNNEL OF CATSKILL AQUEDUCT. 
 
 Fig. 2. 
 
FROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 75 
 
 The contractors began to assemble plant early in June, as soon 
 as they received notice to begin work, and with the exception of 
 Shaft 16 on Contract 66 and Shafts 21 and 23 on Contract 67, where 
 possession of the necessary land was delayed by condemnation pro- 
 ceedings, work at all shafts was well under way by the last of July. 
 The site of Shaft 20 at Delancey and Eldridge Streets was pur- 
 chased at private sale and but little delay occurred. The com- 
 missioners of condemnation who were appointed to appraise the City 
 Aqueduct real estate filed their oaths of office on August 7, 1911, 
 and after a necessary interval for surveys and inspection, the con- 
 tractors had possession of all shaft sites early in September. 
 
 Sinking Shafts ix Earth. 
 The sinking of the shafts in earth in the three northerly con- 
 tracts, 63, 65 and 66, offered no unusual difficulties, since the rock 
 was generally found at or near the surface or could be reached by 
 ordinary open cut methods. Before beginning shaft-sinking, the 
 contractors in most instances excavated and sheeted the large cham- 
 bers at the top of the shafts which are from 20 to 30 ft. wide, 30 
 to 50 ft. long, and have a depth of 15 to 40 ft. below the surface. 
 Stiff-legged derricks were set up for the excavation of these cham- 
 bers, and were also used in sinking of the upper portion of the 
 shafts. Plate 34, Fig. 1, shows the sheeting and timber in the cham- 
 ber at Shaft 17 which is typical of most of the chamber excavations. 
 The steel sheeting and timber bents which were put in at Shaft 5 
 below the chamber excavation to reach the rock is seen in Plate 
 34, Fig. 2. Special care was exercised at this shaft to prevent any 
 loss of ground, because the old Croton Aqueduct is on an earth em- 
 bankment only 20 ft. away. No settlement occurred about the ex- 
 cavation and after the concrete lining was placed the steel sheeting 
 was removed and grout forced into the ground outside of the con- 
 crete walls. Steel sheeting was also employed in the earth portion 
 of Shaft 18, where the rock was 30 to 40 ft. below the surface. 
 
 Pneumatic Caissons. 
 
 At the shafts of Contract 67 the rock floor is covered by some 
 depths of generally pervious earth, of which 30 to 100 ft. are below 
 the water table, and the shafts are situated in localities where seri- 
 ous damage might have resulted from attempting to reach the rock 
 
7G PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 
 
 by means of sheeted excavation or open caissons. Pneumatic caissons 
 were accordingly sunk to rock and sealed in before the rock shafts 
 were started. Five of these caissons were constructed entirely of 
 reinforced concrete with V-shaped cutting edges made up of plates 
 and structural steel; three of these caissons, those at Shafts 19, 
 20 and 22, had an outside diameter of 19 ft. 4 in., and walls 2 ft. in 
 thickness; and two of them, those at Shafts 23 and 24, had outside 
 diameters of 24 ft. and walls 3 ft. in thickness. Plate 35, Fig. 1, 
 shows the top of one of these larger caissons at Shaft 24 with hori- 
 zontal and vertical reinforcements in place ready for concreting. 
 These vertical reinforcing rods have sleeve nuts projecting through 
 slots in the inner sloping face of the cutting edge, to which other 
 rods of the same diameter will subsequently be connected and con- 
 creted into the rock shaft below 7 to prevent the overturning of the 
 caisson and the rupture of the lining. Plate 35, Fig. 2, presents a 
 view at the bottom of the same caisson where rods to be bent out 
 to hold the deck have been exposed. 
 
 The steel cutting edges of these caissons were first erected upon 
 the bottom of the chamber excavation and the caissons were alter- 
 nately concreted and sunk of their own weight until the water table 
 was reached. With the exception of the caisson at Shaft 23 all 
 of the concreting of the wall of the caissons was done before build- 
 ing the concrete deck and putting on the air, for the reason that 
 there would have been serious delay and some danger in interrupt- 
 ing the sinking to concrete after having once started. Plate 36, 
 Fig. 1, shows the caisson at Shaft 23 when completed ready for com- 
 pressed air. This is the deepest of the six caissons, 118 ft., of which 
 when this photograph was taken, 40 ft. were in the ground. 
 
 With the exception of Shaft 19, the shallowest caisson, the con- 
 tractor installed two shafts in each caisson with a Mattsen lock of 
 50 or 110 cu. ft. capacity on each. The general design of these 
 caissons, the location of the deck, the shafting and the locks are 
 seen in Plate 37 which shows a section of the caisson at Shaft 20. 
 One of the two locks of the smaller size at this shaft was used for 
 materials and the other for the men. Except for the deeper shafts 
 no bucket was used in the man lock, the men using the ladderway 
 in passing in or out. In the deepest, however, that at Shaft 23, two 
 locks of the larger size were used at the beginning for the removal 
 
PLATE 35. 
 THE MUNICIPAL ENGINEERS 
 OF THE CITY OF NEW YORK. 
 SPEAR ON PROGRESS OF CITY 
 TUNNEL OF CATSKILL AQUEDUCT. 
 
 Fig 2. 
 
PLATE 36. 
 THE MUNICIPAL ENGINEERS 
 OF THE CITY OF NEW YORK. 
 SPEAR ON PROGRESS OF CITY 
 TUNNEL OF CATSKILL AQUEDUCT. 
 
 Fig. 2. 
 
fkookfs.s of i itv ti nnkl of catskill AQUEDUCT. 
 
 of the excavation, but as the pressure increased one was reserved 
 entirely for the men and they were taken in and out in a bucket. 
 The general dimensions ami weights of each caisson, the maximum 
 air pressures used and the frictional resistances estimated at the 
 times of movement of the caisson when bottom free ami clear are 
 shown in the following table: 
 
 Caisson shaft. 
 
 < >ut<ide diam- 
 eter, tV»>t . 
 
 »- = 
 
 I 1'- 
 
 h| 
 
 5si . 
 
 m 
 
 z ~ ~ -~ 
 
 g S S J 
 
 -~ ci 
 
 u-i . 
 : •- / 
 
 ~~ ~ 
 § = ~ 
 
 'I -7. -' 
 > / ^ 
 
 " a ■ 
 B 
 
 ti 
 
 a- — 
 
 )s - 
 ~ = 
 
 l> - 
 
 Hi . 
 
 E - ' 
 - .- "r | 
 
 * * 
 
 Estimated fric- 
 tion and penetra- 
 tion resistance. 
 Lbs. per sq. ft., 
 making allow- 
 ance for air 
 pressure. 
 
 19 
 
 19.8 
 
 2.0 
 
 46.1 
 
 466 
 
 700 
 
 R 
 
 300 to 400 
 
 80 
 
 19.8 
 
 2.0 
 
 1C2.0 
 
 1 < >.-,« » 
 
 2 luO 
 
 39 
 
 630 
 
 22 
 
 19.3 
 
 2.0 
 
 96.0 
 
 978 
 
 2 470 
 
 28 
 
 630 to 736 
 
 23 .... 
 
 24.0 
 
 3.0 
 
 117.6 
 
 2 323 
 
 4 612 
 
 45 
 
 sTn tO 1 450 
 
 24 
 
 24.0 
 
 3.0 
 
 95.4 
 
 1 780 
 
 4 046 
 
 29.5 
 
 945 to 1 685 
 
 You will note that the frictional resistance on these circular caissons rauged from 
 300 lb. to 1 6K5 lb. per sq. ft. Tnis wide range is probably to be explained by tne differ- 
 ence in the sizes of caissons and in the material encountered, by slight irregularit m 
 some of the casings, the depth of penetration of the cutting edge below the excavation 
 in the working chamber and the straightness with which the caisson was sunk. 
 
 Good progress was made in sinking the caissons in earth. The 
 average advance of the 5 circular caissons was 8| ft. per 24 hours; 
 the record progress was made at Shaft 20, where the caisson was 
 dropped 10.9 ft. in 24 hours. 
 
 The method of sealing these concrete caissons into the rock is 
 by far the most interesting feature of the work and the most difficult. 
 The work had to be done under the highest pressure and on the 
 average only 8 cu. yds. of rock could be excavated daily: including 
 the time from the beginning of the excavation of the rock to taking 
 off the pressure the sealing took about three weeks. The method 
 of sealing is shown in detail on Plate 38. When the rock had been 
 excavated to the required depth, which was fixed at 5 ft. below 
 the lowest point of the rock at the cutting edge, the bottom was 
 leveled up, a bench of concrete was placed a foot thick around the 
 shaft with wood blocks set under the cutting edge to receive the 
 shock of the dropping caisson, and a collar of 1 : 2 mortar carried 
 up to 3 ft. above this. In this collar and passing through the bench 
 at least six 2-in. grout pipes were set as shown, communicating with 
 the three horizontal grooves formed in the ring for the purpose 
 of insuring a free circulation of the grout around the caisson. The 
 caisson was lowered to the bench after the cement had set. a ring 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 
 
 79 
 
 -Position of shoe when mortar is 
 
 ^8 -2" grout pipes around perimeter 
 at 5 'aboue shoe 
 
 f % \ i "clearance . 
 
 m 
 
 ^8-2 'grout pipes around perimeter 
 at 3' above shoe 
 
 2' grooves in mortar collar tormed 
 by nailing i round strips fo form. 
 Vertical grooves, every 6 ft. around 
 perimeter, connect the horizontal groooes 
 the whole forming a q routing drainage 
 system. Just prior to grouting, air is blow 
 in to clean surfaces. 
 
 -Oakum 
 
 Steel plate z 'thick 
 
 total of 6-2' pipes around perimeter, 
 two at each groove. 
 
 '6 x 6 wooden blocks capped with 3 "steel K kVV ' 
 plate, placed at 4' intervals to receive shock of dropping 
 caisson. Five inches of oakum placed under the entire 
 perimeter prior to dropping, to insure water tightness. After 
 caisson is dropped, grouting is immediately started. 
 
 d'-O" collar may be reduced to ZH) "collar 
 depending on rock conditions and ground 
 Drowned water level 
 
 Traced cJ.&d. 
 Cached 
 
 C.ty of New York 
 BOARD OF WATER SUPPLY 
 
 CATSKILL AQUEDUCT 
 
 CITY TUNNEL 
 CONTRACT 67 SECTION S 
 COMPRESSED AIR WORK 
 SEALING CAISSON IN 
 EARTH TO ROCK 
 SCALE r=r 
 
 NOVEMBER 3, I9U 
 
 File c-~' fcT s.4rMC'°> acccmtso. 
 
 Plate 38. 
 
(SO i'i:o<;Ki;ss of city ji nm i. of catskiu. aqi fdlct. 
 
 of oakum being placed to make a temporary seal and the space 
 between the outer wall of the cutting edge and the ring was grouted 
 with neat cement. Other grout pipes through the walls of the 
 caisson wore thou filled and after the expiration of something like 
 12 hours the pressure was taken oft'. On the average 3 days were 
 required to place the concrete bench and collar, and to lower and 
 grout the caisson. In the case of one caisson, that at Shaft 20, the 
 leakage through the seal when the pressure was removed was only 10 
 gallons per 24 hours, and the maximum leakage at Shaft 213, the 
 deepest earth shaft, was only 7 gallons per minute, which was sub- 
 sequently grouted off. The mass of those loaded caissons was such 
 that it was exceedingly difficult to keep them plumb, and more diffi- 
 cult to right them when once out of perpendicular. The maximum 
 deviation from the perpendicular on the length of the caissons was 
 about 8 in. in case of caisson at Shaft 24, which was !).*) ft. deep, 
 while the caisson at Shaft 20, 102 ft. long, went down practically 
 plumb, as shown below: 
 
 Shaft. 
 
 Outside Diameter 
 of caisson, 
 feet. 
 
 Total depth 
 of caisson, 
 feet. 
 
 Amount, in Inches, by which Caisson 
 was out of Plumb when Sealed. 
 
 In total length. 
 
 Per foot of 
 length. 
 
 19.... 
 20. . . . 
 22. . . . 
 
 24.... 
 
 19.3 
 19 3 
 19.3 
 24.0 
 24.0 
 
 46.1 
 102.0 
 
 96.0 
 117.6 
 
 95.4 
 
 1.00 
 1 .00 
 7.37 
 6.72 
 7.90 
 
 0.022 
 0.010 
 0.074 
 0.055 
 0.075 
 
 Shaft 21 differs materially from the other five shafts of Contract 
 07, because of the support which it was necessary to provide for 
 the superstructure over the drainage chamber at the top of the shaft; 
 instead of a single caisson to rock for the shaft and a number of 
 smaller caissons to carry the superstructure the contractor chose 
 the alternative permitted under the contract of sinking and excavat- 
 ing to rock four rectangular concrete filled wooden caissons 37 ft. 
 to 43 ft. in length, and 5 ft. thick, on which the superstructure will 
 be built. 
 
 These caissons, with half -moon closures, are shown in plan on 
 Plate 39. The rock here was only 30 to 40 ft. below the surface 
 and these caissons, which were made 37 ft. high, were sunk without 
 incident. The frictional resistance was about 1 200 lb. per sq. ft. 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 81 
 
82 
 
 PROGRESS OF CITY TUNNEL OF CAT8KILL AQUEDUCT. 
 
 The grano-diorite, when uncover* d, was found to he hard hut seamy ; 
 eonsiderahle water entered through the bottom of the excavation 
 and came in at the corners of the caissons where not tightly sealed 
 on the rock. Some leakage also entered the upper portion of the 
 shaft, as it was excavated, and it was necessary to put in a tem- 
 porary lining in the shaft, place a blanket of concrete over the 
 entire bottom of the excavation within the wall caissons, and grout 
 off the leakage. 
 Shafts in Rock. 
 
 The sinking of the shafts in rock has been carried on during 
 the entire 24 hours of each working day, with 3 shifts of men. The 
 force employed at a well-organized shaft is shown below. This is 
 a circular shaft, in Manhattan schist, 18 ft. in diameter. 
 
 General: 
 
 Superintendent 2 
 
 Timekeeper 1 
 
 Storekeeper 2 
 
 Watchman 2 
 
 Magazine tender 2 
 
 Foreman 1 
 
 Rigger 4 
 
 Carpenter 4 
 
 Laborer 4 
 
 Bottom of Shaft: 
 
 Shift boss 3 
 
 Drill runners 9 
 
 Muckers 19 
 
 Top of Shaft: 
 
 Foreman 2 
 
 Compressor engineer 3 
 
 Blacksmith 3 
 
 Blacksmith's helper 3 
 
 Electrician 3 
 
 Top man 4 
 
 Signalman 3 
 
 Hoist runner 3 
 
 Pipeman 6 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 83 
 
 Much Bins : 
 
 Team and driver 
 Laborer 
 
 4 
 
 1 
 
 Total 
 
 Practically all of the drilling was done by this organization 
 during the 12 midnight to 8 a. M. shift; 8 cut holes and one center 
 hole were shot about 7:30 a. m.; after mucking out, 14 relief holes 
 were fired, about noon, and, after mucking, the 20 rim holes were 
 fired, about 4:30 p. M. Six Ingersoll Eotating Hammer drills were 
 used; the cut holes were drilled 8 ft. in depth, the relief holes 7.5, 
 and the rim holes 7.0 ft. 310 ft. of holes were drilled per round. 
 An average advance of 6.0 ft. was made each round, and 1.9 lb. of 
 60% dynamite per cu. yd. were used. 
 
 On Plate 40 is shown the arrangement of drill holes in the shafts 
 of Contract 66. This arrangement is practically the same as that 
 followed in the shafts of the other contracts. You will note that 
 30 to 40 holes were drilled in one round in the circular shafts and 
 43 to 46 in rectangular shafts; 4 to 6 ft. were pulled at each 
 advance. The amount of dynamite used at the shafts in the built-up 
 portions of the city averaged from 1.5 to 2 lb. per cu. yd. excavated. 
 At some shafts, located at a safe distance from buildings, where the 
 rock was harder, 3 to 3£ lb. of dynamite were used. Both 40%" and 
 60% dynamite were used. 
 
 Records of 25 to 30 ft. per week have been frequently made in 
 the shafts of the City Tunnel, but the best record thus far made 
 was at Shaft 10, where an advance of 37 ft. per week was made. 
 The progress per month has not approached the record made at the 
 other tunnels of the Catskill Aqueduct, principally because of the 
 short depths of the shafts thus far completed, which did not permit 
 of effecting the necessary organization, and because of the frequent 
 interruptions and the consequent disorganization of the drilling 
 and mucking force resulting from the interruptions necessary to 
 concrete the shaft at intervals of 100 ft. The best month's work 
 thus far recorded was 108 ft., which was done at Shafts 8 and 10 
 of the Pittsburg Contracting Company's contract, though a some- 
 what better performance was made at Shaft 20, one of the shafts 
 
84 PROGRESS OF CITY TUNNEL OF CAT8KILI AQUEDUCT. 
 
 <it Holbrook, Caboi & Rollins Corp oration contract, where, in addi- 
 tion to LOO ft of shaft sinking, <;;, ft of the shaft was concreted 
 in a month. A record of 96 ft. in three weeks was made at Shaft 
 14 by the Dravo Contracting Company, who were sinking this shaft 
 for Grant, Smith & Company and Locher. 
 
 The progress that has been made in shaft sinking to date is 
 summarized in the following table: 
 
 Progress in Excavating Rock Shafts. 
 
 Contract No. 
 
 Shaft No. 
 
 Average speed, 
 in feet per 
 
 month, includ- 
 ing time of 
 concreting. 
 
 Maximum 
 weekly progress, 
 in feet. 
 
 Maximum 
 monthly pro- 
 gress, la feet. 
 
 03 
 
 1 
 
 87.8 
 
 M 
 
 59 
 
 
 2 
 
 
 22 
 
 62 
 
 
 8 
 
 52.0 
 
 33 
 
 75 
 
 
 4 
 
 47.0 
 
 32 
 
 80 
 
 
 5 
 
 51.3 
 
 ■ 9 
 
 62 
 
 65 
 
 6 
 
 40.8 
 
 2» 
 
 70 
 
 
 7 
 
 47.0 
 
 25 
 
 ?5 
 
 
 8 
 
 97.8 
 
 32 
 
 108 
 
 
 9 
 
 45.0 
 
 22 
 
 73 
 
 
 10 
 
 70.8 
 
 37 
 
 108 
 
 
 11 
 
 57.2 
 
 26 
 
 80 
 
 
 IS 
 
 48.0 
 
 21 
 
 52 
 
 66 
 
 18 
 
 40.0 
 
 26 
 
 55 
 
 
 14 
 
 86.0 
 
 33 
 
 100 
 
 
 15 
 
 68.0 
 
 32 
 
 95 
 
 
 16 
 
 76.0 
 
 28 
 
 87 
 
 
 17 
 
 57.8 
 
 24 
 
 65 
 
 
 18 
 
 51.0 
 
 15 
 
 53 
 
 67 
 
 19 
 
 78.0 
 
 30 
 
 75 • 
 
 
 30 
 
 100.0 
 
 35 
 
 100 
 
 
 21 
 
 58.8 
 
 25 
 
 78 
 
 
 22 
 
 73.0 
 
 27 
 
 78 
 
 
 28 
 
 82.0* 
 
 21 
 
 
 
 24 
 
 56.9 
 
 24 
 
 ei 
 
 * Two weeks only. 
 
 The rock shafts have been, on the whole, dry, and the rock, gen- 
 erally, sound. The rock, however, has ordinarily a dip in excess of 
 45°, and shows evidence in places of much folding and slipping. 
 At Shaft 4, at the lower end of Jerome Park Reservoir, bad ground 
 was encountered not far above the tunnel grade. Fifty holes were 
 drilled at the bottom of the excavation, and over 900 bags of neat 
 cement were used in grouting, before the water was cut off. When 
 the shaft was finally sunk through the wet ground it was found that 
 the rock was badly broken, and there was one seam in which the 
 rock had so much disintegrated that there was little left but sand. 
 
SG 
 
 PROGRESS OF CITY TUNNEL 01 CAT8KILL LQUEDUOT. 
 
 This, and the other thin seams which were filled with the same ma- 
 terial, did not take the grout readily, and this fact accounts for the 
 largo number of boles that were necessary. Alter the slaii't was 
 excavated some 10 ft. below the bad ground, a thick reinforced con- 
 crete lining was placed and the ground behind filled with grout. 
 Somewhat similar ground was found nt Shaft 24, in Fort (Jreene 
 Park, Brooklyn, and the grouting appears to have been equally 
 successful. 
 
 As stated above, the placing of the concrete lining has interfered 
 somewhat with rapid progress on the City Tunnel shafts; in most 
 shafts, however, the rock was Buch that some support would have 
 been necessary at frequent intervals, so that time lost in concreting 
 was more apparent than real. 
 
 The concrete lining of the lower portions of the shafts below 
 the river valves represented the finished lining of the final water- 
 way. Only the irregular section valve shafts, 13 and 18, were tim- 
 bered. The experience on this work has demonstrated the ad- 
 vantages of the concrete lining; it gives no trouble after once in 
 place, and effectually cuts off the inflow of water to the shaft. The 
 method of making a closure in the concrete lining is shown in 
 Plato 41. 
 
 Progress on Tunnel. 
 
 The first shot was taken from the tunnel heading at Shaft 14 
 on December 6, 1911, and the tunnels were started at other shafts 
 shortly after that date. At present, 16 of the 24 shafts have been 
 completed to tunnel grade, and at some of the shafts the tunnels 
 are well under way. Ordinarily, from two to six weeks has been 
 required after the completion of the shaft to change over equipment 
 and install cages in readiness for tunnel driving. The progress 
 on the tunnels, even where the headings are at some distance from 
 the shaft, has not yet equalled the record made on other parts of 
 the Catskill work. A number of circumstances have contributed 
 to this comparatively small progress, such as are necessarily inci- 
 dent to the execution of shaft and tunnel excavation through the 
 heart of our great city. 
 
 The storage of the amount of dynamite required for a tunnel 
 of the size of the City Tunnel, constructed in the midst of con- 
 gested business and residential districts, has presented a serious 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 87 
 
S8 
 
 PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 
 
 problem for those having the responsibility in such matters. Only 
 150 to 200 pounds of powder were allowed to be stored during the 
 shaft-sinking period, and only 400 pounds are now permitted tem- 
 porarily in the surface magazines. The Municipal Explosives Com- 
 mission has approved underground magazines excavated in the rock 
 at the end of a drift 75 ft. in length, the entrance to which from the 
 tunnel will not be less than 100 ft. from the foot of the shaft. This 
 magazine is to have a heavy door, hung in a concrete bulkhead, at 
 the entrance to the magazine drift, which is designed to close when 
 an explosion occurs in the magazine and prevent the escape of the 
 gases of combustion in the magazine and minimize the rush of air 
 up the shaft. The design of this magazine has been worked out by 
 the engineers of the City Aqueduct Department and is based on 
 French and German practice. A number of these magazines are 
 under construction, and one of them, that at Shaft 18, is practically 
 finished. 
 
 Disposal of Excavation. 
 
 The contractors on the lower sections of the City 'runnel have 
 encountered no more serious problem than that of disposing of the 
 materials excavated from the shafts and tunnels. At the first four 
 shafts, 1 to 4, inclusive, it was possible to find areas adjacent to or 
 near the shaft sites on which the earth and rock could be spoiled 
 at comparatively little expense; but at the other shafts it has been 
 necessary to haul everything to the waterfront, or other points of 
 disposal at some distance from the shaft. On Contract 65, through 
 an arrangement with the Park Department, a large amount of the 
 excavation is being dumped along the Xorth River near 129th 
 Street, to fill an area on the river front that is being reclaimed for 
 a park. A portion of the excavation on Contract 66 has gone to 
 make a fill at the foot of West 79th Street, but more of it is going 
 to the docks, to be carried to sea, and much of that on Contract 67 
 is being similarly disposed of. 
 
 Plant Layouts. 
 
 The amount of land available to the contractors about the shafts 
 of the City Tunnel was necessarily limited in some localities to 
 hardly 5 000 sq. ft., and it is interesting to see how the contractors 
 have arranged their plants on such small spaces. Plate 42 shows 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 
 
 S9 
 
'JO PEOGBB8S OB CITY TUNNEL OP OATSKILC AQUEDUCT. 
 
 the arrangement of the contractor's plant at Shalt 19 and the 
 Bowery, during the period of sinking this shaft in rock. This is a 
 good example of a small space well utilized. Referring to this plant, 
 you will see that the compressors, blacksmith shop, cement shed, 
 store house, contractor's office, and drives occupy the ground level, 
 while on the deck above are the hoists, repair shops, shelter for 
 men, dynamite magazine, and engineer's and doctor's office, and open 
 storage room for forms and other equipment. The equipment for 
 sinking this shaft and placing the concrete lining is tabulated 
 below : 
 
 Siiait-Sixkinc Plant. 
 
 
 Manufacturer. 
 
 Size. 
 
 Operating mechanism. 
 
 Head frame. . 
 
 Compound 
 compressor 
 
 Compound 
 compressor 
 
 Exeter Machine Works.. - 
 
 \ Lackawanna Bridge ) 
 
 1 Co I 
 
 , 
 
 Ingersoll-Rand Co 
 
 1 
 1 
 
 1 
 
 Single. 5 ft. diam. 
 by 4 ft. 6 in. 
 geared drum 
 
 76 ft. high 15* tons-| 
 
 181 in. and 111 in. | 
 cylinders. 16 in. 
 stroke. 900 cu. ft. \ 
 free air per min- I 
 
 1 ute J 
 
 21 i in. and 12} in. } 
 cylinders, 18 in. | 
 stroke. 1 30(j cu. f 
 ft. free air per j 
 
 Direct connected Q E in- 
 duction motor; 112 h.p.; 
 440 volts. 
 
 Constructed for double 
 balanced cages when 
 tunneling. 
 
 Direct connected G. E. 
 synchronous motor: 164 
 h. p ; 6 600 volts: with 
 6g kw.— 125-volt exciter. 
 
 Direct eonnecte 1 G. K. 
 synchronous motor: 215 
 b. p.; 6 600 volts, with 
 9i kw.- 125-volt exciter. 
 
 
 
 Manufacturer. 
 
 Number aDd 
 
 size. 
 
 Operating mechanism. 
 
 Hard ham- 
 mer drills.. 
 
 Sinking 
 
 f Ingersoll-Rand Co I 
 
 IMcKiernan Terry < n 
 
 \ Drill Co j J 
 
 1 Sullivan Machinery / n 
 
 [ Company \ 
 
 * Cameron Steami 1 
 / Pump Works f 
 
 ^our 96 lb 
 
 rwo521b 
 
 rhree 41 lb 
 
 2 x 5 x 13 in. stroke, 
 100 gallons. 
 
 Machine rotating bit. 
 Hand rotating bit. 
 
 Hand rotating bit. 
 
 Shaft Concreting Plant. 
 
 Concrete 
 
 mixer. . 
 
 j Ransome Concrete ) . 
 * Machine Co )' 
 
 r 3 
 i 
 
 1 Blaw Collapsible! 
 I Steel Centering Co. j 
 
 I 
 
 cu. yd. capacity... . -j 
 
 5 ft. of forms equals 
 28 pieces. Thickness 
 of plate = Ys in. In- 
 terior bracing of 4 
 curved 6 in. channels 
 and 3 x 2 in. angles. 
 
 Direct connected G. E. di- 
 rect current, 25 h.p. 
 motor, 240 volts. 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 91 
 
 In Plate 36, Fig. 2, is seen a photograph of Shaft 19, taken 
 from the west, which shows the hoist, head-frame and muck bins in 
 place for shaft-sinking. But little will have to be done here when 
 the shaft is completed to prepare for tunnel driving, except to in- 
 stall the cages and tipples. 
 
 Power Plants. 
 
 In drawing up contracts for the City Tunnel, it was planned 
 to eliminate, as far as possible, any annoyance to the public from 
 noise, smoke and dust arising from the prosecution of the work, 
 particularly at the shafts in the built-up sections of the city, 
 by requiring that, so far as practicable, electric power be used in- 
 stead of steam. On Contract 63, that of Mason & Hanger Com- 
 pany, comprising Shafts 1 to 5, inclusive, which are located in the 
 undeveloped portions of the city, steam power has been largely 
 used; through arrangements made between the contractor and the 
 Park Commissioner of the Bronx, the contractor agreed to fill for 
 the city a large area of swamp in Van Cortlandt Park, without 
 other consideration than that he be allowed to locate there a cen- 
 tral steam compressor plant and to lay pipes through the park 
 in which to distribute the air to the five shafts of his contract. 
 This compressor plant, which has a capacity of 12 500 cu. ft. of 
 free air per minute, has been in operation for several months, and 
 compressed air is used at the shafts of this contract for drills and, 
 to some extent, for pumping. Steam hoists were used temporarily 
 for sinking the shafts, but the permanent hoists are operated by 
 electricity and some pumping is being done by electrically-driven 
 pumps. By the above plan, all smoke and dirt is confined to the 
 central power plant, which is located in a section of the park where 
 no annoyance can arise. 
 
 On the next contract, 65, that of the Pittsburg Contracting 
 Company, comprising Shafts 7 to 12, inclusive, no steam plants 
 have been used; even the temporary hoists were driven electrically. 
 Ingersoll-Band motor-driven compressors, having a capacity of 
 350 cu. ft. of air per minute, sufficient for the hand-hammer drills 
 used in shaft-sinking, have been placed at five of the shafts; but 
 two of the shafts, 9 and 11, have been sunk entirely by electric 
 drills, and no compressors have been installed. 
 
 On Contract 66, that of Grant, Smith & Company and Locher, 
 
92 
 
 ['Ko<;j;i;ss of city tiwkl of catskill A.QUEDUOT, 
 
 compressed air for the operation of the drills is being supplied to 
 the first three shafts, 13, 14, and 15, from a central compressor 
 plant equipped with three electrically-driven two-stage compressors 
 of the Sullivan Machinery Company, having a total capacity of 
 6 300 cu. ft. of free air per minute. This plant is located in Cen- 
 tral Park, within the contractor's enclosure, at Shaft 14, and the 
 air is piped through the transverse roads and along the sidewalk of 
 Eighth Avenue to the other two shafts. At the three southerly 
 shafts of this contract, 1G, IT, and 18, and in all six shafts of 
 Contract 67, Shafts 19 to 24, inclusive, which is being carried on 
 by Holbrook, Cabot & Rollins Corporation, each shaft has an inde- 
 pendent electrically-driven compressor plant, comprising, on Con- 
 tract G6, a single Ingersoll-Rand two-stage machine of a capacity 
 of 2 100 cu. ft. of free air per minute, and on Contract 67 two 
 Ingersoll-Kand two-stage compressors, one of a capacity of 1 200 
 cu. ft. and the other 900 cu. ft. of free air per minute. 
 
 Alternating current is supplied to the shafts in the Boroughs of 
 Manhattan and the Bronx by the New York Edison Company and 
 its subsidiaries, and to those in Brooklyn by the Edison Electric 
 Illuminating Company of Brooklyn, at a voltage of about 6 600. 
 This current is stepped down to 2 200 for the hoists and compressors 
 on Contract 65, and to 220 volts for power, lights and blasting on 
 Contracts 63 and 65. The alternating current at 6 600 volts is 
 delivered directly to the compressors on Contracts 66 and 67, and 
 from this reduced to a voltage of 440 and 220 for power, and to about 
 110 for lighting and blasting. Direct current at about 220 volts is 
 used for the hoists, at 110 volts for lights and small motors on Con- 
 tracts 66 and 67. 
 
 Cages and Hoists. 
 
 The shafts thus far completed have been equipped with single- 
 drum Flory and Lidgerwood hoists, which are capable of operating 
 at a speed of 400 ft. per minute two balanced cages, each with a 
 5 x 8-ft. platform. On two contracts, 65 and 67, platform cages, 
 weighing about 3 000 lb., are to be installed ; on the other two, 63 
 and 66, self-dumping cages, weighing about 4 500 lb., are being 
 put in. The safety devices on all cages are tested as soon as in- 
 stalled, and at frequent intervals thereafter, and the hoists are 
 being equipped with devices to prevent overwinding of cables. 
 
PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 93 
 
 Drills. 
 
 On Contracts 63 and 66, and to a large extent on Contract 67, 
 large 3:1- and 3§-in. piston drills, mounted on tripods, have been 
 used for sinking the shafts. On Contract 65, however, the Pitts- 
 burg Contracting Company has successfully used, on 5 of their 
 7 shafts, several kinds of hand-hammer or Jap drills, including 
 the Sullivan drill, which weighs about 60 lb., and the larger 
 Ingersoll Rotating drill, which has a weight of about 90 lb. The 
 use of these large hand drills marks a distinct advance in shaft- 
 sinking methods. Among their advantages, it should be noted that 
 the hand drill requires for its operation but one drill-runner, with- 
 out a helper; the drill is easily handled in the shaft; no time is lost 
 in setting it up or moving it, and it may be operated while mucking 
 is going on. The drill cuts fully as fast as the large tripod drill, 
 with much less air, and little trouble, other than with the drill 
 steel, is experienced in drilling 7-ft. to 8-ft. holes in moderately 
 hard rock. Of course, the hand drill makes a smaller hole than the 
 larger piston drill. The rotating Jap drills are also being used 
 successfully on Contract 67, but in the hard granitic rock of the 
 Brooklyn shafts their use has been confined to trimming holes, the 
 cut and reliever holes being drilled with 3|-in. piston drills, 
 mounted on tripods. 
 
 Three types of electric drills have also been used on Contract 65, 
 the Fort Wayne, the Pneumelectric, and the Dulles-Baldwin. The 
 second type of drill is used in sinking Shaft 11, and the last in 
 sinking Shaft 9. Alternating current at 220 volts is delivered to 
 these drills through a cable and manifold suspended from the top 
 of the shaft. The electric drills effect a large saving in power, and 
 no doubt, when perfected, this type of drill will have a large field 
 of usefulness. 
 
 Acknowledgments. 
 
 I wish to make acknowledgments to Messrs. Lazarus White and 
 Bertrand H. Wait, Division Engineers, in immediate charge of the 
 City Tunnel, and to Mr. J. S. Langthorn, in charge of the Execu- 
 tive Division of the City Aqueduct Department, and to Mr. M. J. 
 Ungrich, Assistant Engineer, and others, for their assistance in 
 compiling the information contained in this paper. 
 
94 DISCUSSION : PROGRESS OF CITY TUNNEL OF 0AT8K1LL LQUBDUOT. 
 
 DISCUSSION. 
 
 A Member. — On the first slide shown of the pipe lines running 
 from Brooklyn to Staten Island, there seemed to he an extension 
 on the Jersey coast, one coming out at about Port Afonmouth, or 
 somewhere there. 
 
 Walter K. Speak. M. M. E. N. Y. — We are not invading \.\\ 
 Jersey. The conduit leaving Shaft 23 goes through Third Avenue, 
 Park Place, Fifth and Sixth Avenues, to Bay Ridge, and crosses 
 the Narrow- a I Seventy-ninth Street, to the foot of Arrietta Street 
 on Staten Island, and from that point passes in the most direct route 
 up to Silver Lake, where the proposed Reservoir is to be constructed. 
 That is the end of that conduit. The other conduit, leaving the 
 tunnel at Shaft 24 at Fort Greene Park, is to be laid through 
 Willoughby Avenue to Queens Borough, and ends at Thompson 
 Avenue. Those are the only conduits we propose to build. 
 
 Sidney W. Hoag, Jr., M. M. E. N. Y. — Mr. Spear, what do you 
 mean by the terms waterway -hafts and section valve shafts 1 What 
 is the distinction between such shafts and others % 
 
 Mr. Spear. — The waterway shafts of the City Tunnel are those 
 through which water will be drawn from the tunnel for the supply 
 of the City. 
 
 Only one of the shafts of the City Tunnel — Shaft No. 1 — is a 
 construction shaft similar to most of those in the other pressure 
 tunnels of the Catskill Aqueduct which are filled in and plugged 
 when the tunnel is finished. One other shaft — Xo. 11 — is a drain- 
 age shaft, without a waterway, so that twenty-two out of the twenty- 
 four shafts are waterway shafts and have one or more riser pipes 
 in them connecting with the distribution mains. 
 
 A section valve will be placed across the tunnel at Shafts 13 
 and 18, which will serve to cut off the portion of the tunnel on 
 either side, for inspection or repairs. These shafts are, therefore, 
 termed section valve shafts. 
 
 Mr. Hoag. — What is the grade of the flow line across the X ar- 
 rows from Brooklyn to Staten Island? 
 
 Mr. Spear. — With a flow of 250 million gallons per day in the 
 City Tunnel and a delivery of 10 million gallons per day to Staten 
 Island, the gradient in the 36-in. pipe across the Narrows will be 
 about Elevation 260 above sea level. With the full flow of 500 
 million gallons per day through the City Tunnel, the gradient in 
 the Narrows will be about Elevation 230. 
 
 Mr. Hoag. — You propose to lay the 36-in. pipe across the Nar- 
 rows in a dredged trench? 
 
 Mr. Spear. — Yes, in a dredged channel; and the pipe will prob- 
 ably be laid from a cradle supported on one or more scows, much the 
 
DISCUSSION : PROGRESS OF CITY TUNNEL OF CATSKILL AQUEDUCT. 95 
 
 same as a pipe of the same size was laid across the Harlem River 
 some time ago. 
 
 The conduit from Shaft 23 is to be a 66-in. steel pipe, and a 
 portion of it is now being la.id on Sixth Avenue. From Fifth 
 Avenue and Thirty-sixth Street to Silver Lake, with the exception 
 of that section in the Narrows, 48-in. cast-iron pipe will be laid. 
 The first section of the conduit from Shaft 24 to Queens Borough 
 is also to be a 06-in. steel pipe as far as Willoughby Avenue and 
 Broadway, and a 48-in. cast-iron pipe the remainder of its length. 
 Three out of the four contracts in Brooklyn and Queens Boroughs 
 are now under way. 
 
 Samuel C. Thompson, M. M. E. X. Y. — Is it intended, Mr. 
 Spear, that the entire pressure from the tunnel will enter into the 
 distribution i 
 
 Mr. Spear. — In the low-pressure districts there will be regulating 
 valves in these chambers at the top of the shafts, by which any 
 desired pressure may be maintained on the distribution side. In 
 the high-pressure districts of Manhattan, Brooklyn and Richmond 
 it will not, of course, be necessary to make such reductions in 
 pressure. 
 
 Mr. Hoag. — Then, Mr. Spear, the idea is, by this system to 
 deliver water direct from the Catskills into the houses, without 
 the intervention of receiving or distributing reservoir-? 
 
 Mr. Spear. — That is true, except for Hill View Reservoir in 
 Yonkers, just beyond the City line, and the terminal reservoir in 
 Staten Island. 
 
 Mr. Hoag. — Will the Hill View Reservoir be a part of this sys- 
 tem? Will the head there control the pressure? 
 
 Mr. Spear. — Yes, the head there will control the pressure in the 
 City Tunnel. 
 
 William F. Laase, M. M. E. N. Y. — Mr. Chairman, I would like 
 to ask Mr. Spear what would happen if the valve at the foot of the 
 riser should get out of order? What provision has been made for 
 repairing it, or how long a time it would take if serious accident 
 happened to it? 
 
 Mr. Spear. — Xone of these valves have yet been purchased or 
 delivered, but I understand that they are of the simplest design 
 and the likelihood of their getting out of order is exceedingly small. 
 Should it be impossible at any time to open or close one of these 
 valves when desired, there would be nothing else to do but to close 
 off the nearest section valve and pump the water out of the tunnel. 
 We believe that this will seldom be necessary, because these riser 
 valves are to be used only in an emergency, and will therefore not 
 be operated frequently. There are two valves on each connection 
 
9G DISCUSSION : PROGRESS of city tunnel of CATSKILL A.QUBDUOT. 
 
 a1 the top of the shaft, one of which is to be a service valve and 
 the second which is kept in reserve and on whieh very little WQ&T, 
 of course, can take place. 
 
 Mk. EOAO. — Is there anything, M r. Spear, in connection with 
 this Oity Tunnel system t hat prohibits its becoming a part of the 
 present distribution system in Manhattan! 
 
 Mr. Spkar. — The gradients in a large part of the present dis- 
 tribution system of Manhattan are too low to permit of the City 
 Tunnel becoming part of this system, in so far as a flow may 
 under present conditions take place in either direction between 
 the tunnel and the distribution system. If it were desired to do 
 so, however, the tunnel could in part be operated at a lower gradient 
 than now proposed by closing off one of the section valves and 
 using a portion, say between Shafts 13 and 18 or that portion 
 between 18 and the Brooklyn shafts, as a part of the distribution 
 system. 
 
 Lazarus White, M. M. E. N. Y. — As I understand the paper, it 
 was primarily a progress report. It was not intended to be a full 
 exposition of why the Oity Aqueduct tunnel was built; that was 
 pretty thoroughly gone into for a period of three or four years and 
 the project won out handsomely. 
 
 When we started work on the Catskill Aqueduct, it appeared 
 that the pressure tunnel would be an exceptional feature of the 
 aqueduct. As the pressure tunnels were built they began to grow 
 more in favor and they won out up the State where deep valleys 
 had to be crossed. It finally dawned on the engineers that it would 
 be a mighty good thing in the city to distribute the Catskill supply 
 by pressure tunnels and to avoid the trouble of constructing sur- 
 face pipes. The project was such a large one that it naturally met 
 with opposition. We are now far enough advanced to know that 
 the difficulties which the opposition raised were largely imaginary. 
 There has been no special difficulty in sinking the shafts or driving 
 the tunnels in the City; we have found that the deeper we go the 
 better we find the rock, and the rocks which we found treacherous 
 in Manhattan at 60 ft. are much better at 200 ft. Except in a few 
 instances the tunnels are remarkably dry. As for the quality of 
 the rock in the tunnel we know now that these tunnels will not be 
 difficult to construct, and we believe that we have done the hardest 
 work in getting down to rock through the cover of sands and 
 gravels. 
 
 It would appear to me that, in the future, deep tunnels will be 
 resorted, to for other purposes besides delivering water. Instead 
 of periodically ripping up the streets, it seems that tunnels dis- 
 tributing gas and electricity might be built. Considering the amount 
 
discussion: progress of city tunxel of catskill aqueduct. 97 
 
 of work we are doing, I think anybody will admit the disturbance 
 at the surface is very small. The shafts are inconspicuous, and, 
 except for a few of our neighbors, only a few are being disturbed. 
 
 The average progress of sinking the shafts in the City will 
 probably average higher than on our other tunnels, although the 
 individual records will not be as high. The tunnels will probably 
 be constructed at a rate not as high, relatively, as the shaft sinking, 
 due to the unfavorable conditions of working in the City and the 
 character of the rock structure. 
 
 Mr. Ho ag. — What is the relative cost per linear foot between 
 shaft and tunnel? 
 
 Mr. White. — It is hard to state from the contractors' prices, 
 since the contractors have a tendency to bid a little high on the 
 shafts to pay for the first expenditure on plant and equipment. 
 About two to one is probably the actual relative cost. 
 
 Mr. Hoag. — Is not the fact that there has been so little water 
 in the shafts and tunnels somewhat of a revelation? Was that 
 anticipated by the geologist? 
 
 Mr. White. — I believe the amount of water has been less than 
 could reasonably be expected. Some of the shafts have been almost 
 bone dry. 
 
 Bertrand H. Wait, M. M. E. X. Y. — I have nothing of interest 
 to add to Mr. Spear's paper, unless it might be a few words in 
 regard to some of the details which affected progress on the City 
 shafts up to date. 
 
 Previous to starting work on the Catskill system, the shafts 
 which had been sunk in Xew York State were very limited, both 
 in number and depth. As a general rule, these shafts formed a 
 very small proportion of the work in hand, and the contractors 
 did not organize especially for them. They put an organization 
 on the ground to take care of the major part of the work and let 
 their men sink the shafts as best they could. 
 
 When the Catskill work was started, it was realized that the 
 number of shafts to be sunk and their depth made them something 
 of a problem in themselves. Shaft-sinking organizations were 
 brought in from the Pennsylvania and West Virginia, coal regions 
 by the different contractors. These men were all experienced when 
 they first came on the Catskill work; they sank shafts on the dif- 
 ferent contracts all the way from Ashokan to the City and became 
 more expert as they got accustomed to the different rocks encountered 
 in this part of the country. The result was that the City Tunnel 
 reaped the benefit, as we were able to get the best of the gangs 
 which had been working along the line. It was due to these organi- 
 zations that most of the good progress has been made here. 
 
98 DISCUSSION : PROGRESS OF CITY TUNNEL OF OATSKILL AQUEDUCT. 
 
 Another thing which helped out progress on the City Tunnels 
 was the faet that most of the shafts were circular in section. In 
 these circular shafts it is possible to do all the drilling for a. round 
 on one shift, mucking the other two shifts, and in this way getting 
 one round out of the shaft each 24 hours. This works out well 
 both for speed and cost. All the drillers can be carried on one 
 shift and each day the drillers and muckers have a definite task be- 
 fore them. The rock also stands up much better in circular shafts 
 than in the rectangular ones, and it is possible to sink safely to 
 greater depths before following up with concrete lining. 
 
 A method of sinking followed to a considerable extent on the 
 City Tunnels, which was not tried out in this part of t he country 
 previously, was the use of small hammer or jap drills. Several 
 types of jap drills were tried out, but the best progress was made 
 with the Ingersoll rotating drills. These drills weigh about 90 
 pounds each and can be handled by one man. They require no 
 tripods, and only one helper to every four or five drill runners. 
 In ordinary rock, holes to a depth of 10 ft. can be drilled as 
 fast as with the ordinary slugger drills. On account of having 
 no tripods or heavy drills to get into the hole, the shifts can get in 
 so much quicker than when they have the big drills to handle. 
 When the drilling is finished they can also pick up and get out of 
 the hole in a shorter time. 
 
 Conditions were not as favorable for speed in the City as up 
 the State, where the shafts were outside of city limits and where 
 the blasting did not disturb the residents. There were some delays 
 in getting started, due to the fact that it took some time to get the 
 necessary permits to go ahead with the work. All that the con- 
 tractors up State had to do was to set up a derrick and boiler and 
 start work. The time of shooting in the City has, in general, been 
 kept within the hours of 7 a. m. and lip. m., as it was found that 
 blasting during the late evening or early morning hours disturbed 
 the residents in the vicinity of the shafts. Another thing which 
 caused some delay was the problem of getting muck away from the 
 shafts. In only a few cases was it possible to spoil near the shafts ; 
 it all had to be hauled a considerable distance by teams or motor 
 trucks. 
 
 Taking everything into consideration, the general progress on 
 these shafts to date has been better than could be expected. This 
 has been due primarily to the superior organization of the con- 
 tractors and the good quality of the rock encountered. The most 
 notable advance in methods that has been developed on the City 
 Tunnel has been the use of jap drills in sinking. 
 
discussion: progress of city tunnel of catskill aqueduct. 99 
 
 Herbert M. Hale." — I would like to say that, of course, in start- 
 ing work in the City of the magnitude of the City Tunnel, the 
 problem of our relations to the several departments of the City 
 government was an important one. The contractors have, without 
 exception, found that the City departments are well organized, and 
 contractors have been very well treated by everybody concerned. 
 Of course, the Board of Water Supply could not buy all the private 
 property at the site of the City Tunnel shafts which was necessary 
 to carry on this work, but the other departments came to the rescue 
 and allowed us to bridge streets and encroach a little on the high- 
 ways and parks. With all the restrictions placed by the City on our 
 operations, there was one thing the City department did not do — 
 they did not set any limit as to how high we could go above the 
 ground with our plant. In many cases by building several decks, 
 as at Shaft 19, we have thereby more than doubled the working areas. 
 
 Mr. Spear. — I want to add a little more about this question of 
 permits. The Board of Water Supply have not the broad powers 
 which the old Rapid Transit Commission had — to go anywhere 
 they chose — and we have had to make application to the depart- 
 ments having jurisdiction over City lands for permission to occupy 
 them, and the contractors have had to go to them for many per- 
 mits for carrying on their work. I want to state that we have 
 been very well treated by the other City departments. Further- 
 more, I want to say that if there has been any delay in securing 
 permits it has been due to the contractors who came in here with- 
 out knowledge of the City departments, and who did not at first 
 know just where to go to get the permission they sought. 
 
 Mr. Hoag. — It does seem that, for work of this magnitude and 
 importance, it is being conducted with far less fuss and feathers, 
 as far as the lay observer can see, than has characterized any great 
 public or municipal improvement heretofore. I mean by the "lay 
 observer," those outside of the Board of Water Supply, and I think 
 it is due largely to the co-operation of the various departments in 
 lending their aid and assistance on lines of least resistance. 
 
 William F. Laase, M. M. E. N. Y— I have been led to believe 
 that a daily supply of about 200 000 000 gal. will be available in 
 Brooklyn by the end of 1915, and I would like to ask if the rate 
 of progress on the work confirms that belief? 
 
 Mr. Spear. — Yes. Contract No. 67, the last contract in lower 
 Manhattan and Brooklyn, is the one which will take longest to 
 complete. That is to be completed in December, 1915, and, at the 
 present time, the contractors are ahead of their schedule. 
 
 ^Engineer with Holbrook, Cabot and Rollins Corpoiation, Contract 67 of City Tunnel. 
 
I