| TABLE 7 | |||
|---|---|---|---|
| Rates of Water Consumption | |||
| From Journals of American and New England Water Works Associations | |||
| City | Population in Thousands | Per Cent Metered | Consumption, Gal. per Capita per Day |
| Tacoma, Wash. | 100 | 11.6 | 460 |
| Buffalo, N. Y. | 450 | 4.9 | 310 |
| Cheyenne, Wyo. | 13 | 270 | |
| Erie, Pa. | 72 | 3.0 | 198 |
| Philadelphia, Pa. | 1611 | 4.6 | 180 |
| St. Catherines, Ont. | 17 | 3.2 | 160 |
| Port Arthur, Ont. | 18 | 14.7 | 145 |
| Ogdensburg, N. Y. | 18 | 0.2 | 140 |
| Los Angeles, Cal. | 516 | 77.9 | 140 |
| Wilmington, Del. | 92 | 43.7 | 125 |
| Lancaster Pa. | 60 | 34.6 | 120 |
| Richmond, Va. | 120 | 75.2 | 115 |
| St. Louis, Mo. | 730 | 6.7 | 110 |
| Springfield, Mass. | 100 | 94.4 | 110 |
| Keokuk, Ia. | 14 | 64.5 | 105 |
| Jefferson City, Mo. | 13.5 | 34.4 | 100 |
| Muncie, Ind. | 30 | 23.8 | 95 |
| Burlington, Ia. | 24 | 4.5 | 90 |
| Council Bluffs, Ia. | 32 | 75.5 | 80 |
| San Diego, Cal. | 85 | 100 | 80 |
| Monroe, Wis. | 3 | 100 | 80 |
| Yazoo City, Miss. | 7 | 84.1 | 75 |
| Oak Park, Illinois. | 26 | 100 | 70 |
| Portsmouth, Va. | 75 | 8.1 | 65 |
| New Orleans, La. | 360 | 99.7 | 60 |
| Rockford, Ill. | 53 | 93.0 | 55 |
| Fort Dodge, Ia. | 20 | 96.0 | 50 |
| Manchester, Vt. | 1.5 | 69.0 | 45 |
| Woonsocket, R. I. | 47.5 | 95.6 | 35 |
Attempts have been made to express the rate of sewage flow in different units other than in gallons per capita per day. A unit in terms of gallons per square foot of floor area tributary has been suggested for commercial and industrial districts. It has not been generally adopted. The rates of flow in New York City as reported in this unit by W. S. McGrane are given in Table 11.
The most successful way to predict the flow from commercial or industrial districts is to study the character of the district’s activities and to base the prediction on the quantity of water demanded by the commerce and industry of the district affected.
25. Fluctuations in Rate of Sewage Flow.—The rate of flow of sewage from any district varies with the season of the year, the day of the week, and the hour of the day. The maximum and minimum rates of sewage flow are the controlling factors in the design of sewers. The sewers must be of sufficient capacity to carry the maximum load which may be put upon them, and they must be on such a grade that deposits will not occur during periods of minimum flow. The maximum and minimum rates of flow are usually expressed as percentages of the average rate of flow.
| TABLE 8 | |||
|---|---|---|---|
| Sewage Flow from Different Classes of Districts | |||
| Arranged from data by Kenneth Allen in Municipal Engineer’s Journal, Feb., 1918. | |||
| District | Gallons per Capita per Day | Gallons per Acre per Day | |
| Buffalo, N. Y. From Report of International Joint Commission on the Pollution of Boundary Waters: | |||
| Industrial: Metal and automobile plants. Maximum. | 13,000 | ||
| Industrial: Meat packing, chemical and soap. | 16,000 | ||
| Commercial: Hotels, stores and office buildings. | 60,000 | ||
| Domestic: Average. | 80 | ||
| Domestic: Apartment houses. | 147 | ||
| Domestic: First-class dwellings. | 129 | ||
| Domestic: Middle-class dwellings. | 81 | ||
| Domestic: Lowest-class dwellings. | 35.5 | ||
| Cincinnati, Ohio. 1913 Report on Sewerage Plan: | |||
| Industrial, in addition to residential and ground water. | 9,000 | ||
| Commercial, in addition to residential and ground water. | 40,000 | ||
| Domestic. | 135 | ||
| Detroit, Mich.: | |||
| Domestic. | 228 | ||
| Industrial, in addition to residential and ground water. | 12,000 | ||
| Commercial, in addition to residential and ground water. | 50,000 | ||
| Milwaukee, Wis. 1915 Report of Sewerage Commission: | |||
| Industrial, maximum. | 81 | 16,600 | |
| Industrial, average. | 31 | 8,300 | |
| Commercial, maximum. | 60,500 | ||
| Commercial, average. | 37,400 | ||
| Wholesale commercial, maximum. | 20,000 | ||
| Wholesale commercial, average. | 9,650 | ||
| TABLE 9 | ||||||||
|---|---|---|---|---|---|---|---|---|
| Observed Water Consumption in Different Classes of Districts in New York City | ||||||||
| From data by Kenneth Allen in Municipal Engineers Journal, for 1918 | ||||||||
| Hotels | Daily Cons. Gals. per 1000 Sq. Ft. Floor Area | Tenements | Daily Cons. Gals. per 1000 Sq. Ft. Floor Area | Office and Loft Buildings | Daily Cons. Gals. per 1000 Sq. Ft. Floor Area | |||
| Building | Max.[[19]] | Avg. | Location | Max.[[19]] | Avg. | Building | Max.[[19]] | Avg. |
| Hotel Biltmore. | 470 | 368 | 78th–79th St. and B’way. | 256 | 192 | McGraw Bldg. | 309 | 206 |
| Hotel McAlpin. | 753 | 694 | 410 E. 65th St. | 350 | 295 | N. Y. Telephone Bldg. | 194 | |
| Hotel Plaza. | 630 | 578 | 30th St. and Madison Ave | 306 | 188 | Met. Life Bldg. | 256 | |
| Hotel Waldorf Astoria. | 618 | 482 | 27 Lewis St. | 307 | 250 | 42d St. Bldg | 271 | |
| Hotel Astor. | 732 | 492 | 258 Delancey St. | 267 | 226 | Municipal Bldg. | 118 | |
| Hotel Vanderbilt. | 604 | 545 | Equitable Bldg. | 366 | 268 | |||
| Average | 634 | 526 | Average | 297 | 230 | Average | 338 | 219 |
| TABLE 10 | |||
|---|---|---|---|
| Sewage Flow from Different Classes of Districts Based on 1915 Report of Milwaukee Sewerage Commission | |||
| Ratio of maximum to average rate for department store district. | 1.755 | ||
| Ratio of maximum to average rate for hotel district. | 1.65 | ||
| Ratio of maximum to average rate for office building district. | 1.51 | ||
| Ratio of maximum to average rate for wholesale commercial district. | 2.1 | ||
| Average and maximum gallons per thousand square feet of floor area: | Avg. | Max. | |
| For department store district. | 232 | 407 | |
| For office building district. | 541 | 891 | |
| For wholesale commercial district. | 164 | 344 | |
| For all districts except wholesale commercial. | 381 | 618 | |
| Average and maximum gallons per day: | |||
| For all districts except wholesale commercial. | 17,700 | 29,800 | |
| For wholesale commercial district. | 9,650 | 20,000 | |
| TABLE 11 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Rates of Consumption Predicted for Different Districts in New York City | ||||||||||
| District | Net Bldg. Area in Sq. Ft. per Acre for Ultimate Consumption | Avg. Number of Floors | Observed Cons. in g.p.d. per 1000 Sq. Ft. Max. | Observed Cons. in g.p.d. per 1000 Sq. Ft. Avg. | Predicted Mean Cons. | Predicted Mean in Million Gals. per Acre per Day | Predicted Dry Weather Flow, c.f.s. per Acre | Predicted Max. Dry Weather Flow, c.f.s. per Acre | Measured Avg. Dry Weather Flow, c.f.s. per Acre | Measured Max. Dry Weather Flow, c.f.s. per Acre |
| Hotel and midtown. | 24,800 | 15 | 634 | 526 | 500 | .20 | .29 | .34 | 1.04 | .146 |
| Midtown and financial. | 24,800 | 15 | 338 | 219 | 300 | .12 | .18 | .23 | .078 | .110 |
| East and West of midtown. | 24,800 | 10 | 297 | 230 | 300 | .074 | .12 | .15 | .057 | .097 |
| Apartment, 59th to 155th Sts. | 20,400 | 7 | 230 | 300 | .043 | .06 | .09 | |||
| Manhattan north of 155th St. | 20,400 | 5 | 230 | 300 | .031 | .05 | .08 | |||
| Midtown district consists of department stores, large railroad terminals, industrial and loft buildings, and sky-scraper office building. | ||||||||||
It is difficult to set any definite figure for the percentage which the maximum rate of flow is of the average. Fluctuations above and below the average are greater the smaller the tributary population. This relation can be expressed empirically as
M = 500
P⅕,