Problem 1. Consider a drainage system that consists of horizontal drains located at an elevation ho above the base of an unconfined aquifer of thickness b = 10 m (see Figure 1). The recharge rate is r= 100 mm/yr, and the hydraulic conductivity of the aquifer is K = 1 m/d. The design condition of the drainage system is to avoid ponding at the ground surface. You can ignore the vadose zone for this problem. 1. Obtain the relation between the half-distance between drains, L, and the elevation of the drains, ho. Plot this function over the range of feasible lengths. 2. The cost of each individual drain can be split as the cost of the material (fixed) and the cost of installation (which is assumed to be proportional to the depth b-ho). If the fixed cost is $500 and the installation cost is $100 per meter of aquifer length per meter of depth, can you build a drainage system for less than $1 per meter of aquifer length? If so, what depth ho and spacing 2L would you choose? K= 1 m/day 2L r = 100 mm/yr Figure 1: Schematic of the drainage system. b

Problem 1. Consider a drainage system that consists of horizontal drains located at an elevation ho above the base of an unconfined aquifer of thickness b = 10 m (see Figure 1). The recharge rate is r= 100 mm/yr, and the hydraulic conductivity of the aquifer is K = 1 m/d. The design condition of the drainage system is to avoid ponding at the ground surface. You can ignore the vadose zone for this problem. 1. Obtain the relation between the half-distance between drains, L, and the elevation of the drains, ho. Plot this function over the range of feasible lengths. 2. The cost of each individual drain can be split as the cost of the material (fixed) and the cost of installation (which is assumed to be proportional to the depth b-ho). If the fixed cost is $500 and the installation cost is $100 per meter of aquifer length per meter of depth, can you build a drainage system for less than $1 per meter of aquifer length? If so, what depth ho and spacing 2L would you choose? K= 1 m/day 2L r = 100 mm/yr Figure 1: Schematic of the drainage system. b

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

See similar textbooks

Similar questions

A circular culvert 164 ft long extends between two reservoirs as shown. The difference in water surface elevation (?h) between the two reservoirs is 6.6 ft, and both the culvert entrance and exit are fully submerged. The culvert has a diameter of 8.0 ft. Assume that the entrance loss coefficient is 0.5 and the exit loss coefficient is 1.0. Determine the discharge rate in the culvert using: (1) Darcy- Weisbach equation (f = 0.02) (2) Hazen-Williams formula (Ch = 100) L = 164 ft
Water table in a canal command receives a recharge at the rate 2.5 mm/day. Sub-surface ditch drains at a spacing of 2 km are provided for the sub-surface drainage. Estimate the maximum rise of the water table at steady state. Given: hydraulic conductivity of the soil = 10 m/day, depth of the impervious layer below initial water table position = 20 m. Assume the ditches to be fully penetrating.
An unconfined aquifer is 10 m thick and is being pumped so that one observation well placed at a distance 76 m shows a drawdown of 0.5 m. On the opposite side of the extraction well is another observation well 100 m from the extraction well, shows a drawdown of 0.3 m. Assume the coefficient of permeability of 50 m/day. a.) What is the discharge f the extraction well? b.) Suppose the well at 100 m from the extraction well is now pumped. Show with a sketch what this will do to the drawdown. c.) Suppose the aquifer sits on an aquaclude that has a slope of 1/100. Show with a sketch what this will do to the drawdown.
Q1: The design flow for a water treatment plant (WTP) is 1 MGD (3.8x10 m³ /d). The rapid mixing tank will have a mechanical mixer and the average alum dosage will be 30 mg/L. The theoretical mean hydraulic detention time of the tank will be 1 minute. Determine the following: a) the quantity of alum needed on a daily basis in kg/d, b) the dimensions of the tank in meters for a tank with equal length, width, and depth, c) the power input required for a G of 900 sec' for a water temperature of 10 °C. Express the answer in kW, given that u = 1.307 × 10³Kg/m.s.
A confined aquifer with two piezometers measuring pressure head at two different locations 1500 ft apart. The aquifer has hydraulic conductivity of 2.4 x 10-4 ft/sec. Assume the width of aquifer into the page is 6 miles and the flow is one dimensional from left to right. Compute the total flow in ft³/sec. el. 282 ft 10.5 ft -1500 ft el. 276 ft Aquiclude Confined aquifer Aquiclude
The initial rate of infiltration of a watershed is estimated as 53 mm/hr, the final capacity is 5 mm/hr, andthe hydraulic conductivity, k as 0.4hr-1. Use Horton’s equation to find: • The infiltration capacity at t = 3 hr and 6 hr• The total volume of water infiltrated over the 6-hr period.
Question One Determine the flow rate in a confined aquifer with a hydraulic conductivity of 20m/d, and thickness of 6.6m. The initial piezometric surface is 14.53 above the lower confining bed, causing the piezometric surface to be 13.85m at a radius of 40m and a 14.31m at a radius of 85m. The solution should include a labeled diagram.
Problem 3.5 A well of diameter 0.3 m is constructed to the full depth of an unconfined aquifer of thickness of 150 m. The water table is 10 m below the ground surface. A pumping test of 12 m'/hour has resulted a drawdown of 10 m. Assuming ro = 400 m; calculate the coefficient of permeability of the aquifer. If the flow rate increases to 18 m'/hour, and in the absence of any other data, what will be the best estimate for the drawdown in the well?
2. The following description is correct ( ).A. the denser the grid in the flow network, the smaller the hydraulic gradientB. two points on the same equipotential line, the pore water pressure is always the sameC. the same flow network, any two adjacent equipotential line between the potential energy difference is equalD. The direction of the infiltration flow rate is the direction normal to the flow line 3. In the triaxial shear test, the test that keeps the pore pressure of the soil sample at zero throughout the process from the application of the circumferential pressure until the soil sample is damaged is ( ).A. Unconsolidated undrained test B. Consolidated drained testC. Solidification without drainage test D. Solidification fast shear test
A sand layer of the cross-sectional area shown in the figure has been determined to exist for a 800-m length of the levec. The hydraulic conductivity of the sand layer is 1.65 m/day. Determine the quantity of water which flows into the ditch in m/min. Elv. 175 m Levec Elv. 130 m 2 m Ditch 180 m Impervious O Sand
12 Determine the quantity of seepage under the dam cross section shown in m3/s/m if the soil has hydraulic conductivity, k=0.0001 meter cube per second. Note the numbers in the figure from left to right are:2.0m, 1.8m, 2.4m and 8.0 m, respectively. 2.00m 8.00 m 1.80 m Datum 12.40m 777 Enter your answer
There are two identical groundwater pump facilities that is operating 6 kilometers apart. The hydraulic conductivity is 40m/day. Each pump well structure has a tube diameter of 75cm. The original water table has an elevation of 110 m. However, it is maintained that the maximum drawdown (at the tube) is 18m. The water table will not change at the midpoint between the two pump wells. Determine the drawdown at a point 2 km from the pump.