1 Chapter 9 Water Supply Distribution and Wastewater Collection 9 1 The average annual rainfall in an area is 60 cm The average annual evapotranspiration is 35 cm Thirty percent of the rainfall infiltrates and percolates into the underlying aquifer the remainder is runoff that moves along or near the ground surface The underlying aquifer is connected to a stream Assuming there are no other inputs or outputs of water to the underlying aquifer and the aquifer is at steady state neither gains nor loses water what is the amount of baseflow contributed to the stream from the groundwater Solution P 60 cm ET 35 cm I 0 3 60 cm 18 cm R 60 35 18 7 cm At steady state in the aquifer In Out since S 0 Baseflow Infiltration The baseflow is 18 cm Solutions Manual prepared by Ziad Katirji and Heather E Wright Wendel Environmental Engineering Fundamentals Sustainability Design James R Mihelcic and Julie Beth Zimmerman John Wiley Sons New York 2009 2 9 2 Go to the United Nations Environment Programme s Global Environment Outlook Web page http geodata grid unep ch Look up two countries located in different hemispheres What are their current amount of water withdrawals and freshwater withdrawals Are these countries currently experiencing water scarcity or expected to experience water scarcity Solution Students responses will vary Solutions Manual prepared by Ziad Katirji and Heather E Wright Wendel Environmental Engineering Fundamentals Sustainability Design James R Mihelcic and Julie Beth Zimmerman John Wiley Sons New York 2009 3 9 3 Go to the Web site of the U S Geological Survey USGS www usgs gov and navigate to Water Use in the United States Look up the total water withdrawals associated with the following uses in your state thermoelectric irrigation public supply industrial domestic livestock aquaculture and mining Place the eight uses in a table in order of water withdrawals Determine the percent of the total water withdrawals associated with each of these uses Compare these percentages to the national percentages listed in Table 9 3 Discuss how your state compares with the national average Solution Students responses will vary depending on state For Pennsylvania using year 2000 data Use Category Withdraw in MGD of Total Thermoelectric Public Supply Industrial Mining Domestic Irrigation Live Stock Aquiculture Calculated Total 6980 1460 1190 182 132 13 9 9958 70 1 14 7 12 0 1 8 1 3 0 1 100 Solutions Manual prepared by Ziad Katirji and Heather E Wright Wendel Environmental Engineering Fundamentals Sustainability Design James R Mihelcic and Julie Beth Zimmerman John Wiley Sons New York 2009 4 9 4 Go to the Web site of the U S Geological Survey USGS www usgs gov and navigate to Water Use in the United States Look up the total surface water and groundwater withdrawals associated with your state Determine the percent of surface water and groundwater withdrawals relative to total withdrawals in your state Compare these percentages to the national distribution of surface water and groundwater use Discuss how your state compares with the national average Solution Students responses will vary depending on state For Pennsylvania using year 2000 data Use Category Groundwater Surface Water Calculated Total Withdraw in MGD 666 9290 9956 of Total 6 7 93 3 100 Solutions Manual prepared by Ziad Katirji and Heather E Wright Wendel Environmental Engineering Fundamentals Sustainability Design James R Mihelcic and Julie Beth Zimmerman John Wiley Sons New York 2009 5 9 5 Contact your local water or wastewater authority Ask for the annual water usage rates average maximum day minimum day and so on For a water authority ask how much is unaccounted for water for a wastewater authority ask for how much is wetweather flows Use these numbers to estimate a demand factor and per capita or metered connections water usage rates Discuss how your local values compare with the expected range of values described in this chapter Solution Students responses will vary depending on to water authority Solutions Manual prepared by Ziad Katirji and Heather E Wright Wendel Environmental Engineering Fundamentals Sustainability Design James R Mihelcic and Julie Beth Zimmerman John Wiley Sons New York 2009 6 9 6 Estimate your own actual water use during a typical day List your water use activities and estimate the volume of water used for each activity Compare your water usage rate with that of an average per person rate such as 101 gpdc Explain why your rate may be more or less that the average rate How much of your water use do you think was discharged as wastewater Did you do any water use activity that did not create any wastewater Solution Students responses will vary Solutions Manual prepared by Ziad Katirji and Heather E Wright Wendel Environmental Engineering Fundamentals Sustainability Design James R Mihelcic and Julie Beth Zimmerman John Wiley Sons New York 2009 7 9 7 Estimate the daily water demand and wastewater generation for a small commercial area that has the following buildings Clearly indicate all assumptions and the estimated water usage for each building a a 200 room hotel with 35 employees and one kitchen b three restaurants one being an organic restaurant with regionally produced foods another an all you can eat buffet dinner only and the third a vegan deli open from 5 00 am to 3 00 pm c a newsstand that sells magazines refreshments and snacks with one lavatory used only by the employees and d a three story office building with basement employing 140 people and with two sets of men s and women s lavatories per floor Solution Varies based on assumptions used to estimate water use For example Building Unit Number Water Demand Wastewater Generation gpd unit gpd gpd unit gpd Hotel 300 customers 50 15 000 45 13 500 Organic Restaurant 150 customers 9 1 350 3 450 Buffet Restaurant 200 customers 9 1 800 3 600 Deli 150 customers 9 1 350 3 450 2 employees 20 40 20 40 140 employees 15 2 100 13 1 820 Newsstand Office Building Total 21 640 16 860 Solutions Manual prepared by Ziad Katirji and Heather E Wright Wendel Environmental Engineering Fundamentals Sustainability Design James R Mihelcic and Julie Beth Zimmerman John Wiley Sons New York 2009 8 9 8 Estimate the maximum day demand plus fire flow for a residential area The residential area is 400 acres divided into 0 25 acre lots with yards that are 75 ft wide Assume the average population density is 2 8 people per home and the maximum day demand factor is 2 1 Solution Use