Problem

Land use in a new development is given in the following first table. A new school being built will have 1500 students. The average flowrate is 75 L/student, and the peaking factor (ratio of peak flowrate to average flowrate) is 4.0. Average flowrate allowances and the peaking factors for the other developments are shown in the second table. Determine the peak wastewater flowrate from one of the areas (to be selected by instructor).

 

Step-by-step solution

1. Step 1 of 11

   Area 1:

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2. Step 2 of 11

   Consider the type of development as school:

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3. Step 3 of 11

   The average flow rate for a single student is 70 L/student.

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4. Step 4 of 11

   Hence, the average flow rate for 1,500 students is as follows:

   

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5. Step 5 of 11

   The peaking factor is 4.0.

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6. Step 6 of 11

   Find the average flow rate for the given area using the relation.

   

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7. Step 7 of 11

   Substitute 4 ha for area and  for average flow rate per area.

   

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8. Step 8 of 11

   Find the peak flow rate using the peaking factor.

   

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9. Step 9 of 11

   Substitute 4.0 for peaking factor and  for average flow rate.

   

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10. Step 10 of 11

    Tabulate the remaining calculation as in Table (1).

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11. Step 11 of 11

    Type of development	Average flow rate per area, m3/ha.d	Area, ha	Average flow rate, m3/d	Peaking factor	Peak flow rate, m3/d
    Residential	40	125	0.32	3	0.96
    Commercial	20	11	1.82	2	3.64
    School	112.5	4	28.125	4	112.5
    Industrial	30	6	5	2.5	12.5
    Peak wastewater flow rate from the area 1 is	129.6

    Refer to Table (1).

    Thus, the peak wastewater flow rate from the area 1 is .

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