Assignment 1: Field Observation Essay I want 3 page of essay, and every thing are in the file, I have submit one of the file you can you it as example . Sc

Assignment 1: Field Observation Essay I want 3 page of essay, and every thing are in the file, I have submit one of the file you can you it as example . Scanned with CamScanner
Constitution Square, 1st street between N and M street, NE, Washington DC; A
perfect example of Bio-retention
Washington DC is not really a beach town, it more known for its four-season year, and cold rainy
winters. The nation’s Capital is fed by many water sources such as the Potomac, Anacostia and, Rock
Creek River; in consequence, DC has a clear idea of what would happen if a major storm or flood would
occur. Unfortunately, the city has long been vulnerable to bad weather conditions and mostly have been
using sandbags for years. After Hurricane Katrina (2005), the Officials and Mayor decided to use new
methods to prevent such horrible incidents. Since then, more than $100 million have been used to
insure the safety of the citizens. According to DC water, a new project “Clean Rivers Project” reduces
combined sewer overflows (CSO’s) into the District’s waterways – the Anacostia and Potomac Rivers and
Rock Creek. The Project is a massive infrastructure and support program designed to capture and clean
wastewater during rainfalls before it ever reaches our rivers. So far, is has reduced 96% of system-wide
CSO volume (98% in Anacostia), 1 million pounds of nitrogen to Chesapeake Bay and over 18 miles of
tunnels. Another important program that has been established was GI (green infrastructure) program,
consisting on the development of green roofs, gardens, draining pavements and sidewalks. In my
research, I decided to focus on a great example of Bio-retention (sidewalk).
On 1st street NE and M Street, I was able to find a streetscape, which is very common, is DC. The
sidewalk on M street fits the profile for the typical concrete walks and abundant tree pits interrupted by
building entries with amazingly structured-water drainage pavement systems. The bio-retention
planters provide improvements to neighborhood water quality, through plants that soak up rain and
cleanse it before releasing it into the watershed. On this satellite image of the block, we can see that the
bio-retention creates a regular rhythm to the sidewalk with the plants, grasses, shrubs, and trees. The
project I chose has an area of 23644.8 ft^2 (557.39 ft (169.89m) by 42.42 ft (12.32 m)) almost fully
equipped to drain as much storm runoffs
Sidewalk drains, or trench drains, are an excellent storm-water management solution for pedestrian
areas and green infrastructure applications. In this case, I will show how a combination of a sidewalk and
bio-retention can be a main solution for storm-water management.
Bio-retention is the practices that capture and store storm-water runoff and pass it through a filter bed
of engineered soil media composed of sand, soil, and organic matter. Filtered runoff may be collected
and returned to the conveyance system, or allowed to infiltrate into the soil. Bio-retention systems are
typically not designed to provide storm-water detention of larger storms (e.g., 2-year, 15-year), but they
may be in some circumstances. Bio-retention practices shall generally be combined with a separate
facility to provide those controls. Such a process can be described in the following sketch:
Bio-retention can be applied in most soils or topography, since runoff simply percolates through an
engineered soil bed and is infiltrated or returned to the storm-water system via an underdrain.
In this case, we can notice that the street is designed with tree Pits, curb cuts, trench drains, cobbles and
horsetail plants. Many different types of green infrastructures have been used in this case to reduce the
harmful impacts of storm-water runoff.
Trench drains are made with plastic, galvanized steel and cast iron grates, polymer and HDPE trenches
and provide an elongated surface for water to drain from a specific area, such as a driveway, beneath an
un-guttered roof edge, sidewalk or similar area where water tends to collect. Detail of the curb cuts
(solid ramp graded down from top of sidewalk to adjoining street) in the bio-retention planter are made
with concrete and finished at a right angle 4-6” above the street surface. Such a design was made for
water runoff that flows from sidewalk into planter (1’ lower)
According to NOA Atlas 14, a 10year storm about 30 minutes long precipitations for about 1.65” drains
into approximately 10, 9 ft by 2 ft channels directing runoff to main pipe (diameter = 175cm or 68.89”
and about 450ft long) under First St NE.
Knowing that:
Q= C*I*A
(C= 0.80 Table A.1 Runoff Coefficient Factors for Typical District of Columbia Land Uses)
(I=2.3) (A=180 ft^2)
Q= (0.80)*(8.3)*(180) = 1195.2 ft^3/s
Pipe:
V = (1.49/n * R^2/3 * sqaurt(S))
R = A/P = d/4 = 9/4 = 17.23
S = 0.05
A= 3.14(9)^2 / 4 = 63.6 ft^2
Q= (1.49/0.012 * (9/5)^2/3 *sqrt(0.05))(63.6) = 1355.97 ft^3/s
Since Q (Pipe) > Q we can say that the system used in this Bio-retention is efficient. It would allow
enough rain-storm runoff to be evacuated without any risk of flood or degradation of of surrounding
buildings.
https://doee.dc.gov/sites/default/files/dc/sites/ddoe/publication/attachments/Appendix-A.pdf

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