Develop a preliminary design, including flow rates, pipe sizes, and pipe slopes for a trunk sewer to be laid in the development shown in the accompanying figure from 6th to 1st Streets along Peavy Avenue
Assume the following data apply
(a) Saturation population and flow data
Zoning Type of development Saturation population density, person/ha Wastewater flow,
L/capita. d
Residential Single-family dwellings 30 380
Residential Duplexes 50 310
Residential Low-rise apartment 100 260
Residential High-rise apartment 160 220
Peaking factor for residential area
(b) Wastewater flow and peaking data for commercial and industrial areas and institutional facilities.
Area/facility Flow (basis) Value Peaking factor
Commercial m3/ha.d 32 1.5
Industrial m3/ha.d 60 2.2
School L/student.d 80 3.5
Park L/person.d 30 4.0
(c) The average daily attendance at the school is 1000 students.
(d) Assume parks usage is 500 persons/d
(e) Assume flow from upstream area is equal to 0.005 m3/s.
(f) For infiltration allowance
(i) For residential areas, obtain the peak infiltration values from the following figure.
(ii) For commercial, industrial, and institutional areas, also obtain the peak infiltration values from the same figure. However, use only 50 percent of the actual area to compute the infiltration allowance.
(g) Assume inflow can be neglected.
(h) For the hydraulic design equation use the Manning equation with an n value of 0.013.
(i) The local sewer code specifies 200 mm as the smallest pipe permissible.
(j) Use 0.75 m/s as the minimum velocity during the peak flow conditions.
(k) The minimum depth of cover over the top of the sewer is 2.0 m.