The canal strip north of Bird Avenue is also the source of some drainage into the canal. To collect this an interceptor in the east towpath has been planned to run from Bird Avenue to Hertel Avenue. TABLE 128.-Bird Avenue district sewage quantities-Maximum rates of flow, 1950, Buffalo, N. Y. Sewer. TABLE 130.-Bird Avenue district-Estimates of interceptor construction costs, Buffalo, N. Y. 14. Bird Avenue siphon.. It is, however, feasible to effect some economy in the present mode of collection by intercepting the sanitary flow of the Ontario Street subtrunk at a high level and carrying the same over Tonawanda Street 1,500 feet to the Hertel Avenue sewer. The effect of this diversion will be to bring the Ontario Street drainage in at a higher level than could otherwise be secured. The Ontario Street sewer below Tonawanda Street will in such case be used as a storm-water drain and in addition will receive sanitary wastes from that portion of the district below the point of diversion; this latter increment will be intercepted at Cornelius Creek. The existing sewer in Hertel Avenue from Tonawanda Street to Niagara Street is a 57-inch sewer and is really a sanitary extension of the combined sewer which as recently extended stops at Tonawanda Street and Cornelius Creek. In its present form the sewer is large enough (capacity 70 cubic feet per second) to carry the present-day flow of 38 cubic feet per second, but in 1935 will have to be supplemented by the construction of 2,100 feet of 42-inch sewer to successfully deliver the expected 1950 sanitary flow of 95 cubic feet per second. This enlargement of capacity is not the direct result of diverting the Ontario Street flow, though were that not done the duplication could be deferred somewhat. However, even with this disadvantage the scheme described is the more economic, and has been embodied in the plans for this district, though should first cost be the determinent the construction can be deferred to a more opportune time. TABLE 131.-Hertel Avenue district sewage quantities—Maximum rates of flow, 1950, Buffalo, N. Y. The unit cost in Table 134 of $3.72 per lineal foot per foot of diameter is comparable with a similar unit price of $2.39 derived from nine city contracts executed in the period 1908-1911 and covering the construction of 25,600 lineal feet of sewer varying in diameter from 8 inches to 51 inches, and aggregating in cost $142,700. With pipe sewers practically elimi nated, this price reduces to $2.10 per lineal foot per foot of diameter. This statement is introduced as a basis for a rough determination of the reasonableness of the sewer costs included in this report. It will be observed that the different items included in the estimates fall into two classes (a) Those consisting principally of large sewers carrying or diverting considerable quantities of sewage. (b) Smaller sewers designed to pick up residual drainage which, though tangible in the aggregate, is individually small and for its collection requires considerable outlay per unit of flow. This subdivision leads to a possible economy in the first cost of interception by deferring the construction of minor collectors until the completion of the major 1 The result of distributing the total shown in Table 103. In this case the Swan Street district includes the Hamburg pumping station area, which for future collecto design was included with South Buffalo. Taken from Tables 121, 125, 128, and 131 and preserving the differences there recorded from the gross areas in Table 104. These differences arise from planimetering errors and from the omission of certain areas in the detailed subdivisions. A 1930 interpolation of average flow units as derived from Table 120. "Outside city" areas accepted in full as determined for the future with average flow 67 per eant of the maximum rate. |