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River Hydraulics and Sediment Transport - Geoenvironmental Engineering Assignment

I. Current Issue of Geoenvironmental Engineering

Search current article or news in 2018-2019 (googling) related to geoenvironmental issue or problem in the world, and summarize it with your opinion. Also, diagnose and suggest your engineering solution for that based your knowledge learned from the class. The answer should be written within 200 words. Use simple sketches if you need. Be clear, precise, brief, and neat.

II. Contaminant Transport

1. Explain Peclet number regarding diffusion and advection.

2. Explain VOC transport process through composite liner including CCL and geomembrane with a simple schematic.

3. What is partition coefficient?

4. Compare the diffusive transport through geomembrane with low and high partition coefficients. Explain the difference in comparison to CCL.

5. What is the difference between adsorption and absorption?

6. How is tortuosity related to transport phenomenon? Explain the mechanism with diffusion.

7. What is the purpose of attenuation layer in a composite liner?

8. Which is better to use organoclay and lean clay to reduce organic contaminant? Why?

9. Compare the breakthrough curve (C/C0 vs. Time) of advection-diffusion-reaction

1) Constant retardation factor (R), no decay (λ), vary diffusion (D) and seepage velocity (V_s).

2) Pure advection.

3) Constant effective diffusion coefficient (D*) and seepage velocity, no decay, vary retardation factor.

10. How is retardation factor related to sorption?

III. Design of Composite Barrier

Your client has requested that you design a liner for mining tailings. Based on the preliminary investigation, cadmium is serious concern at the site. The analyses indicated that cadmium will not exceed 5 mg/L. Groundwater quality criteria for the site require that the fluxes (J) from based of the liner will not exceed 0.5 kg/ha/yr for cadmium. We are going to compare a single CCL and composite liner including CCL and HDPE GM. For composite liner, you can reduce the thickness of CCL. The clay available for CCL has Gs of 2.7 and a dry unit weight of 15.8 kN/m³. The clay can achieve a saturated hydraulic conductivity of 1 × 10^-7 cm/s. Also, the regulation requires that the depth of leachate on the liner not exceed 300 mm.

The effective diffusion coefficients for cadmium is 2 × 10^-6 cm²/s for clay. The soil partition coefficient for cadmium is 0.35 L/kg. You can assume 10 holes/ha and 10 mm diameter hole with poor contact of GM under imperfect condition. For CQA, the design year is 100 years.

For the design, provide flux vs. time curve and the calculation in EXCEL sheet. Suggest your opinion and recommendation.

IV. Waste Settlement

1. Explain compression process of waste briefly.

2. In a bioreactor landfill, the height of waste disposal is 50 m. The dry unit weight of waste is 8 kN/m³. The water content is 0.35. The organic content is 60%. For immediate compression, 1 m thickness of waste additionally spread out on the existing waste. Estimate total settlement of waste by using C'α method. Phase time and compression ratio for phase can be obtained from attached graph. Demonstrate your calculation.

Attachment:- Assignment File.rar