Page 358 - Facility Piping Systems Handbook for Industrial, Commercial, and Healthcare Facilities

SITE UTILITY SYSTEMS

6.80 CHAPTER SIX

TABLE 6.25 Quantities of Sewage Flow (Continued )

Wastewater flow, gallons per
day per unit
Source Unit Range Typical
Institutional and recreational sources

Cabin, resort Person 34.3–50.2 42.3
Cafeteria Customer 1.1–2.6 1.6
Employee 7.9–13.2 10.6
Campground (developed) Person 21.1–39.6 31.7
Cocktail lounge Seat 13.2–26.4 19.8
Coffee shop Customer 4.0–7.9 5.3
Employee 7.9–13.2 10.6
Country club Member present 66.0–132.0 106.0
Employee 10.6–15.9 13.2
Dining hall Meals served 4.0–13.2 7.9
Dormitory, bunkhouse Person 19.8–46.2 39.6
Hotel, resort Person 39.6–63.4 52.8
Public park with toilets Visitor 5–11 9
Store resort Customer 1.3–5.3 2.6
Employee 7.9–13.2 10.6
Swimming pool Customer 5.3–13.2 10.6
Employee 7.9–13.2 10.6
Theater Seat 2.6–4.0 2.6
Visitor center Visitor 4.0–7.9 5.3

sewer or in a large network serving multiple facilities on a single site. Existing sewers are
frequently found to be quite leaky.
The allowance for infiltration is based on the sewer system when it is reaching the
end of its useful life, not when it is new. The types of joints and the pipe material used
have an effect on the figure selected. Common figures used for private sewer systems are
500 gal/day/mi for smaller sewers and 1000 gal/ day/mi for larger sewer lines. The figure
selected for infiltration does not relate to the infiltration allowance used to test for sewer
acceptance.
For a single facility with a short run to a public sewer, no allowance should be made. If
the run is more than about 1500 ft (450 m), some allowance should be made. For lengths
of run shorter than 1500 ft (450 m), some consideration should be made depending on the
local authorities, stability of ground conditions, and the pipe-jointing methods selected.
Slope of the Piping. The pipe slope is generally determined either by the topography
where the sewer will be installed or the elevation of the outfall where the sewer line will
discharge. Often, it is a combination of both. Keeping a fairly uniform depth of bury will
establish the general slope, with adjustment made to keep the slope uniform in different
sections of the run. If grade is flat, the slope should be based on the optimum velocity, if
possible. If the outfall elevation is the controlling factor, there is little choice in the slope.
If an adequate slope to provide the necessary velocity can’t be maintained, it will be neces-
sary to use a lift station and pump the effluent. The slope of the line shall be steep enough
to provide a minimum scouring velocity of 2 fps.

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