Question

15 CONCEPTUAL QUESTIONS 1. A S12M stormwater capture project is proposed in a local park to relief an overloaded storm drain through a diversion structure and capture up to 7.5 million-gallons of water in storage chambers. The project lowers flood risk, increases regional water supply through groundwate recharge, decreases pollutant discharge into the ocean, and naturally filters water as it percolates through the soil. Between sandy clayey, clayey sand, and poorly graded sand, which is likely to provide the best infiltration rate? Why? (3 pts.) 2. True/False:Coefficients of uniformity and curvature are necessary to classify fine-grained soils. (2 pts.) 3. Name 2 methods used for soil density testing in the field. (2 pts.) 4. Considering Darcy's Law, the higher the hydraulic gradicnt, the faster the discharge velocity Is this relationship true? (2 pts.) 5. For water permeating through soils in parallel, is it the soils with higher or lower conductivity that govern? (2 pts.) 6. Continuing from #5, what if the layers are in series? (2 pts.) 7. Recall our diving and collecting sand example, is effective stress affected by the depth of water surface? (2 pts.)

Answer 1

I have solved all 7 questions. Ask any further query in comment section.

1) Sand is a good material for infiltration puropse. Between 3 choices we have, clayey sand will provide best infiltration rate because major part consists of sand ,and it is not poor graded also.

Sandy clayey will have poor infiltration properties because of clay dominant characteristics. Poorly graded sand will have poor infiltration rate because of only lack of grading of sand.

2. No.

Fine grained materials are mainly classified based on atterberg properties like liquid limit, plastic limit etc.

3. Core Cutter method and Sand Replacement method.

4.True.

As per Darcy law, discharge velocity is directly proportional to hydraulic gradient. V=ki where v is velocity, K is constant and I is hydraulic gradient.

5. In parallel, soil with higher conductivity governs the conductivity as the water will flow through least resistance path.

6. In series, lower conductivity governs the conductivity . It's like slowest velocity vehicle determines speed in one lane road.

7. Yes.

Depth of water surface affects pore water pressure which in turn affects the effective pressure.