An existing 36-inch diameter concrete gravity sewer installed on a slope of 0.25% currently conveys a peak flow rate of 12 cfs. A builder proposes to connect a new residential development to this existing sewer. Projected peak flow from this new development is 4 cfs.
a) Depth of flow in sewer before new development is connected
b) Depth of flow in sewer after new development is connected
c) Flow velocity in sewer after new development is connected
d) Flow type (critical, subcritical or supercritical) after new development is connected
e) Diameter of a sewer to convey combined peak flow of 16 cfs if maximum allowable D/d is 0.85 (i.e. assume you are designing new sewer on the same 0.25% slope)
Please show all work. Thank you so much in advance!
In: Civil Engineering
Sketch a 5 kg thin flat uniform homogeneous square plate of side 600 mm, with a circular opening of radius 100 mm. Determine the area and the mass moments of inertia about the center of mass.
In: Civil Engineering
A concrete mix is required for reinforced concrete wave breaker at seashore where frequent mild freezing and thawing is dominant. A specified compressive strength of 25 MPa is required at the age of 28 days, and the size of the section and reinforcement dictate using a maximum aggregate size of 19 mm. The company had no history of testing concrete used. The coarse aggregate meets the ASTM grading requirements. It has absorption of 2%, a BSG (D) of 2.70 and a unit weight of 1550 kg/m3. The fine aggregates have absorption of 1%, a BSG (D) of 2.7 and a fineness modulus of 2.7. Both coarse and fine aggregates are used while dry. For each bag of cement (50 kg); calculate the number of containers of coarse and fine aggregate equivalent to required mass quantities. The volume of each container is 20 liters; and the loose density of the coarse and fine aggregates are 1250 and 1200 kg/m3, respectively.
In: Civil Engineering
In: Civil Engineering
Discuss remediation verification storage.
In: Civil Engineering
A small city is situated on the countryside. Upstream form the city is a dam that provides the city's water supply. If the dam was overtopped by water, then the dam would fail and all of the water would flood through the city. There is also a danger that the dam might collapse when it is full of water and cause it to fail, also flooding the city.
A) Draw a fault tree for the head event “Dam fails and floods the town” using the following basic events The possibility of dam collapse is (P=0.01)
There is a weakness in the dam that would allow collapse to cause the dam to fail (P=0.1).
Storm occurs that overtops the dam provided that it is mostly full (P=0.002)
Storm occurs that will overtop the dam no matter how full the dam is (P=0.0004)
Dam is mostly full (P=0.4).
B) Determine the probability that the dam will fail and flood the town. For the hours of daylight (assume 12 hours on average) there is someone working at the dam who could send a warning to the city if the dam failed.
There is an 80% probability that this person would be able to get the message to the city in time to evacuate. If the dam failed during the night no one would see it, but there is a 60% chance that the weather conditions would be such that the noise of the dam breaking could be heard by someone in the city and give them enough warning to evacuate everybody.
However, every Saturday night the city has a large party, and nobody would be able to hear if the dam failed anyway.
C) Draw an event tree that can be used to determine the conditional probability that the city will receive warning in time to evacuate.
D) Determine this conditional probability of receiving the warning on time.
E) What is the overall probability that the town will be flooded without an evacuation occurring? Hint: consider your answer for (b).
In: Civil Engineering
Why is precise stability analysis of slopes difficult to predict?
What is the difference between the Stability Number method and the Method of Slices?
In: Civil Engineering
A strip footing 2.5 m wide is loaded on the ground surface with a pressure equal to 175 kPa. Calculate the stress distribution at depths of 2.5, 7.5 and 12.5 m under the center of the footing. If the footing rested on a normally consolidated cohesive layer whose Cc was 0.612 and whose e0 was 1.35 , estimate the settlement of the footing. Assume S = 100%,γ’ = 7.5 kN/m3 , and the total clay layer thickness beneath the footing = 15 m.
In: Civil Engineering
Explain how the use of a shear key below a retaining wall foundation would provide resistance against sliding. How would you as a designer account and quantify the resistance developed by the use of a shear key? Finally, why is the contribution of the shear key so significant for such a small addition?
In: Civil Engineering
Distance from one end of water surface (m) |
depth of water(d) , (m) |
Immersion of current meter below water surface (m) |
||
depth (m) |
sec |
rev |
||
0 |
0 |
— |
— |
— |
2 |
1 |
0.6 |
10 |
40 |
4 |
2.2 |
0.44 |
36 |
48 |
1.76 |
20 |
50 |
||
6 |
4 |
0.8 |
40 |
57 |
3.2 |
30 |
53 |
||
8 |
8 |
1.6 |
46 |
59 |
6.4 |
33 |
57 |
||
10 |
4.2 |
0.84 |
33 |
51 |
3.36 |
29 |
49 |
||
12 |
2.5 |
0.5 |
34 |
52 |
2 |
29 |
53 |
||
14 |
1.2 |
0.72 |
16 |
48 |
16 |
0 |
— |
— |
— |
Rating equation of current meter: v = 0.2 N + 0.04, where N = rev./sec, v = velocity (m/sec).
In: Civil Engineering
The following are average operating data from a secondary activated sludge:
Wastewater flow = 29160 m3/d
Vol. of aeration tanks = 8400 m3
Influent SS = 120 mg/L Influent BOD5 = 170 mg/L
Effluent SS = 22 mg/L Effluent BOD5 = 20 mg/L
Volatile fraction of mixed liquor and effluent suspended solids is 0.65.
Mixed liquor suspended solids = 2500 mg/L
Waste sludge flow = 200 m3/d SS in Waste sludge = 9800
mg/L
Determine the following:
Aeration period, Food to micro-organisms in kg BOD/kg MLVSS /d, Volumetric BOD Loading ,Sludge age ,Observed yield in gVSS/g BOD5 ,True yield in gVSS/g BOD5 assuming a kd of 0.05 d-1 ,Daily oxygen demand
In: Civil Engineering
Please determine the dimensions and air flowrate required for a 3m deep aerated grit chamber designed to remove 70% of 0.02 cm diameter sand [specific gravity = 2.65] at 20ºC. Assume that only particles of 0.001 cm will be scoured away. The wastewater flow rate is 10000 m3/d. Use a b of 0.04 and f of 0.03 for calculations.
In: Civil Engineering
Consider a vapour
compression refrigeration cycle
that uses R-134a as
refrigerant. The R-134a
enters the compressor
as a saturated
vapour at 200 kPa,
and exits the
condenser as a
saturated liquid at
900 kPa. The rate
of refrigeration of
the cycle is to
be 6.0 tons of
refrigeration (1 ton
of refrigeration =
3.517 kW). The
compressor isentropic
efficiency is 80%.
Determine: a) The temperature
of evaporation and
condensation of the
refrigerant; b) Mass flow
of the refrigerant
R-134a, in kg/min; c)
Coefficient of Performance
(COP) of the
refrigeration cycle. Typical
vapour compression
refrigeration systems use
a throttling valve
(or an orifice
tube, or a
capillary tube) to
reduce the liquid
refrigerant’s pressure. This
is a highly
irreversible process. If
the cycle efficiency
is to be improved
by replacing the
throttle with a
rotary expander with
70% isentropic efficiency,
d) What is
the new COP? The
expander delivers its
work developed to
the compressor.
In: Civil Engineering
In: Civil Engineering
A field test is conducted in a confined aquifer by pumping a constant discharge of 14.9 m3/hr from 20-cm-diameter well. After an approximate steady state is reached, a drawdown of 0.98 m is measured in the pumped well. Also measured are drawdowns of 0.73 m, 0.65 m, 0.60 m, and0.57 m, respectively, at 8.0 m, 30.0 m, 80.0 m, and 132 m from the pumped well. Determine the transmissivity of this aquifer. Also, determine how far away from the well you must be before the drawdown becomes less than 0.45 m.
In: Civil Engineering