Australian Civil Engineers

About myself: I am a Civil Engineering Graduate from the University of Melbourne. I created this blog to share my thoughts and knowledge of the various engineering applications I find interesting

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Drainage Information to submit to council for approval:

Drainage Information to submit to council for approval:

  Requirements:

I)              Information required on the plan

i)              Overall catchment area

ii)             Location of internal drainage, pipe size material and grade

iii)           Pit details, showing dimension, surface

iv)           Location of storm water outlet

v)             Details of all internal connections that are connected up to the OSD system before leaving site

II) Design parameters from a city council in Melbourne

            Residential Development:

-       Design storm period of 5 ARI

-       Rainfall intensity based upon Australian Runoff 1987

-       Coefficient runoff: pervious area 0.2, impervious area 0.8

Commercial Development

-       Design storm period of 10 ARI

-       Rainfall intensity same as for residential development

-       Coefficient runoff: pervious area 0.1, impervious area 0.9

II)            Prior to construction, the developer is to:

-       Obtain approvals from relevant authorities

-       Undertake all surveys

-       Dial before you dig, and ensure all service information is present

-       Present professional drafts

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Drainage Design Criterion; theory and practice Part 1

Drainage Design Criterion; theory and practice Part 1

  Definitions:

  #1: Site Discharge Index (SDI)

Definition: SDI is defined as the ratio of the impermeable area that drains directly to a drainage system, to the total area of site. The aim of SMART water management is to reduce the area which discharges runoff from impervious surfaces.

  [Impervious/ impermeable surface such as drive ways and paving prevent rainwater from infiltrating the underlying soil, this creates a more concentrated runoff and may lead to flash flooding in constructed zones such as the CBD]

  #2 Onsite Stormwater Detention

Onsite Stormwater Detention is a way of collecting the rain that falls on a site, storing it temporarily and then releasing it slowly so that it doesn’t worsen downstream flooding.

General Principles in storm water management design:

Consider local constraints prior to design. E.g. Soil type, catchment lie of the land, geotechnical conditions

Manage flows such that there is no nuisance flow to nearby properties.

Conveyance of 100 year ARI (Average Recurrence Interval) runoff

  Design Requirement (For Developers) Table

Roof water and site drainage design

Sized in accordance to AS3500: Plumbing and drainage

Back flow prevention

AS3500 Part 3: Storm Water systems

Noise Emission from pumps

Less than 5dB above ambient (surrounding) background noise level

Lay of storm water pipe beneath buildings

Not permitted unless other alternatives are not achievable. Strict restrictions apply to the choice of piping

Velocity of discharge at curbing

Less than 1.5 meters/sec

Pipe cover

Greater than 450mm in places with vehicle passage, 300mm in pits and court yards

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When global warming finally gets going, it could last for 200,000 years

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New evidence shows that, while we may not see severe climate change in our lifetimes, global warming could snowball into catastrophe in the distant future—and once the climate has shifted, it might not go back to normal for a very, very long time. This is from two new studies on climate change this week. The first,…

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Line Drawing Tips - AutoCAD

1. Basic line closing:  

in the command prompt, type L then enter, this will bring up the line function. Start Drawing by clicking on two arbitrary locations on the work sheet, have a feel for it. 

One the two lines are drawn as shown above, you can choose to close the loop or undo the drawing. To close the loop simply press C then enter, this will connect the last point you have drawn to the first point. This is very handy when your designs are required to be very precisely done. 

2. Turning on time sensitive right click for more efficient drawing: 

Right click the lines you have drawn, click the options button at the bottom. This will open up a window consisted of various tabs and modifications. Select the User Preference tab then under the windows standard behavior section, select right click customization to turn on Time sensitive right clicks. This allows the user to have more control when terminating line drawings. 

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Recap: AutoCAD Drawing Basics

Navigation tips: 

1. When lost in space, use the zoom extent function. This function is found on the  far right tool bar in the 2014 edition of autocad. 

or simply type Zoom, e, in the command Function

A complete list of zoom options can be found under the view tab, play around with them to see what they do individually.  

2. Sketch Movement: also known as the pan movement function, there are three different methods to initiate the pan movement. Personally I find the middle mouse button click and hold method the easiest. Pan movement can also be selected by clicking the right mouse button and selecting it from a list of utilities. 

3. Zoom shortcut: Type Z, Space bar

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Cut Slope Applications - Consolidation and stability through finite element method

* Credits To Jose´ Leita˜o Borges on his publication in Geotech Geol Eng Journal (2008), this article is a mere interpretation of his work. 

1. Saturated Clay Behavior Under Cut Slope Conditions

During the event of a cut slope, the initial stress variation is of a decrease in the total mean stress and an increase in deviator stress. From the total stress relationship (Total Stress = Pwp + effective stress) we can expect pore water pressure to become negative.

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Geosynthetic Clay Liner Cost and Application

Figure 1: Geosynthetic Clay liner application in Australia 

The concept behind the geosynthetic clay liner is fairly simple, it uses two sheets of geo-textiles to sandwich an absorbent clay like material known as bentonite. (Bentonite is useful in the geotechnical engineering world because of its rheological property, i.e. its ability to form a viscous fluid with shear and flow characteristics). Bentonite is often selected as the fill in GCL because of its low hydraulic conductivity, that is, water moves through this medium very slowly. 

Hydraulic Conductivity Estimation and Properties:

Where K = Hydraulic conductivity

C =  Hazen's empirical coefficient, which takes a value between 0.4 and 10.0

D = diameter size of the 10 percentile grain 

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Permeability of Geosynthetic Clay Liner Vs Compacted Clay liners

GCL: 10−10 to 10−12 m/s

CCL: 10−9 to 10−10 m/s

Thickness:

GCL: ~ 6 mm 

CCL: ~600 - 900 mm, compaction with Padfoot, CAT815

General Applications, Municipal Landfills: 

GCL offers some very attractive properties which can be adopted for landfill designs. It is quick and easy to install, able to self repair if the membrane is damaged by swell and cost effective in regions where clay is not readily available. 

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Tips #2 : Creating FPS styled AutoCad pointers

Have you ever been frustrated with the inconspicuous AutoCAD pointer that transforms into a selection box when all you wanted to do was to locate the damn thing? Here is a tip on how you can change the point style so that points are more visible: 

Step 1: Click the Utilities drop box located on the top right corner of AutoCAD interface 

Step 2: Click on Point style, this should bring up the above window, select the X or + pointer for a FPS gaming feel, here is how mine look: 

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Tips: 2D AutoCAD design and interface

Figure 1: Creating Arcs 

There are a number of ways one can create arcs using autocad, in the scenario about I created an arc representing a door in my design plan. The most applicable method I find is the Centre, Start, End sequence found in the create arc drop box. This enables the designer to define a center point and a radius, then simply rotate the mouse until the end result is achieved.