Lab Exercise 8 NAME: 1) Describe what is meant by the term return period? Geog455-49/54 - Urban Site Development Spring 2024 2) What is the runoff coefficient for a 20 acre site where 7 acres are covered by an asphalt parking lot; 11 acres of grass lawns with heavy soils with up to 2% slopes, and 2 acres of grassy lawns with heavy soils and 10% slopes? Use the most conservative values (Higher coefficient values) from Table 9.1 on the last page. 3) Calculate the runoff flow rate for a 1 hour - 10 year design storm event with total rainfall amount of 3.5 inches in 2 hours for the following development types. The site area is 20 acres. Use the most conservative values (Higher coefficient values) from Table 9.1 on the last page. a. Residential: Single Family b. Residential: Multi units Attached c. Industrial: Light Areas 4) Given the following concrete pipe: D = 24”, n = 0.012, and slope = 0.02; what is the flow rate for the following two scenarios (See Figure 21.16): a. Full flow: (y=D) b. Partial full flow: (y = 0.94*D) c. What can you interpret from the results from (a) and (b)? FIGURE 21.16 Nomenclature for pipe flowing partially full. STA 8+ 20 CONST. MH NO. 1 STA 8 + 78.00 LOW POINT 5) From the information provided in Figure 9.12 below answer questions a, b, and c, (See next 2 pages) for a 24-in diameter reinforced concrete storm sewer pipe with wall thickness of 0.30 feet. Figure 9.12 Storm drain clearance. STREET PROFILE S = 0.004 STA 10+23.00 EX WATER MAIN TOP OF PIPE STA 10 + 60.00 CONST. MH NO.2 INV 100.96 a. What is the amount of clearance between the bottom of the storm sewer pipe and the top of the water main crossing at 10+23.00 with top of water main pipe elevation of 98.95 feet? b. What is the amount of cover over the top of the storm sewer pipe at the surface low-point location at 8+78.00 with elevation = 107.30 feet? c. Using the analysis from Q5, what is the maximum flow rate this pipe could carry (Assuming n = 0.012)? Note: calculate this conservatively by assuming the pipe is completely full (D = y)