For many years, snow removed from the campus roads and parking lots has been located to the field next to the river. The plowed snow has a relatively high salt content due to the application of road salt (NaCl) during the winter to keep the campus roads safe. NaCl quickly dissociates in water, resulting in sodium (Na⁺) and chloride (Cl^-) ions. The US EPA recommends that the chloride content in remain below 230 mg/L to maintain healthy freshwater aquatic ecosystems.

Assume the following:

• Chloride is a non-reactive pollutant
• The Raquette River has a chloride concentration of 50 parts per million by mass

(note: 50 ppm chloride by mass = 50 grams chloride per 10⁶ grams water; the density of water is 1 g/cm³, 10³ cm³ = 1 L)

• The Raquette River has an average flowrate of 1500 ft³/s
• The runoff from the field has a chloride concentration of 5000 ppm by mass
• The flowrate of the runoff from field during an average storm is 20 ft³/s
• At the point of discharge from the field, the width of the river is 1000 ft, the depth is 5 ft, and there is near instantaneous mixing within 200 feet downstream of the field.

1. Draw a mass balance diagram for this system.
2. Calculate the chloride concentration of the river just downstream of the field one hour after an average rainstorm begins.
3. Is your estimate for the chloride concentration in the river just downstream of the field above the EPA limit of 230 mg/L chloride? Show your calculations for the comparison.
4. Name one fundamental assumption you needed to make to apply the mass balance approach to this problem. Is this a reasonable assumption? Briefly explain why or why not.

ENMA 480: ETHICS AND PHILOSOPHY FOR ENGINEERING APPLICATIONS

Chairman   Rogers   of   the   Challenger   Accident   Investigation   asked   Bob   Lund:   “Why   did   you  
change   your   decision   [that   the   seals   would   not   hold   up]   when   you   changed   hats?”   What   might  
motivate   you,   as   a   midlevel   manager,   to   go   along   with   top   management   when   told   to   “take   off  
your   engineering hat   and   put   on   your   management hat”?  

Applying   the   engineering-as-experimentation   model,   what   might   responsible   experimenters  
have   done   in   response   to   the   question?

A certain city has a population equivalent to 123456 treatment plant which will serve the community until 2040

. a) Estimate the future population of this city in 2020 and 2040 using constant percent method if the rate constant is 0.0327 /year.

b) Determine the water and wastewater treatment plant design capacities for the period of 2020 to 2040. Use maximum (fmax) and minimum (fmin) factors of 2 and 0.5, respectively (Qmax = fmax Qavg and Qmin = fmin Qavg). Assume an average of 200 L/capita-day is the water consumption rate for the city in 2010 and 80% of the consumed water is collected as wastewater. What is the maximum hourly flow?

c) Determine the daily fire protection water requirement in 2020 and 2040?

d) Estimate the size of a tank for the water treatment plant that can store the raw water for 7 day. Take the depth as 3 m. What would be removal percentages of viruses (diameter = 50 nm) and bacteria (diameter = 1 μm) by this tank? Assume the specific gravity of each micro-organism is 1.05 and the water temperature is 20°

e) Estimate the size of equalization tank for the wastewater treatment plant that can hold the raw sewage for 4 hours. Take the depth as 3 m. What would be the size of the smallest particle size with specific gravity 2.0 that can be 100% removed by this tank? Assume that the water temperature is 20°C

Explain what the process is for installing and removing a sheet pile retaining wall system. What are some of the benefits and limitations of this system?

Denitrification is commonly accomplished as a separate process after carbonaceous BOD removal. An alternative is to recycle mixed liquor to an anaerobic stage at the head end of the aeration tank. What potential advantage does the alternative offer? Explain.

introduction about Types of Parking and parking regulations

(a) What is the chemical form of most nitrogen as it arrives at a wastewater treatment plant? (b) What are the main chemical forms of nitrogen relevant to wastewater and its treatment? Show these in a simple nitrogen cycle.

you are a client asked an architect to design a villa for yourself. You as a client didn’t ask for fees. The architect finished design and tried to collect the fees, and you were reasonable thinking that the fees will be around $3000. Since, this was paid for similar villa design of your friend. The architect argued that the fees should be $5000, discuss the possible action by judge if architect sued you and explain why?     

The velocity field of a permanent, incompressible and isothermal flow is given by

u = a (x^2 - y^2)   (1)
v = −2axy   (2)
w = 0    (3)

Gravitational acceleration acts on the z axis only.

a) Write the Navier-Stokes equations for this flow, canceling the appropriate terms
and replacing the non-zero derivatives with their detailed expression. Be sure to indicate
clearly your assumptions. (4 points)

b) From the result obtained in (a), demonstrate that the pressure field is continuous and therefore
physically possible (2 points)

c) Get the expression for the flow pressure field (4 points)

Design a community drainage system for 20O people

2. In the Rational Method the peak runoff resulting from a rainfall event depends on which of the following factors

1. The frequency and duration of the rainfall event.
2. The size of the area on which the rainfall lands.
3. The characteristics of the surface over which the rainwater flows.
4. The time that has elapsed since the last rainfall event.

1. I, II, III and IV.
2. I, II and III only.
3. I and III only.
4. II and III only.

3. Which of the following are assumptions of the Rational Method?

1. Peak flow occurs when the entire watershed is contributing to the flow.
2. Rainfall intensity is the same over the entire drainage area.
3. Rainfall intensity is uniform over a time duration equal to the time of concentration.
4. Frequency of the computed peak flow is the same as that of the rainfall intensity.

1. I, II, III and IV.
2. I, II, and III only.
3. I and III only.
4. II and IV only.