This is an updated version of this research note describing similar methods that Sara Wylie and myself developed. This research note will be specific to an upcoming project in Southeast Chicago in March. For more information on the project and/or issues in Southeast Chicago, check out the Chicago Wiki page.
What I want to do
Southeast Environmental Task Force (SETF) and other community members in the area are interested in not only mapping the multiple open-air petroleum coke, or 'petcoke' waste piles in the area, but also using this information to estimate the weight and volume of the waste piles. In March I will be collaborating with SETF to produce balloon maps of petcoke piles in the area. We then should be able to estimate the volume of the piles with some additional tools and measurements taken on-site.
The method we'll be using is very similar to measuring the height of a tree with a clinometer. Once the height of the pile is measured, this can be paired with balloon mapping to determine the pile's area, which can be used to estimate its volume.
Using A Spirit Level/Clinometer to Measure Pile Height:
Spirit level or (in)clinometer apps can be downloaded for free on most smartphones - for example, for Android here and for iOS here. If you do not have a smartphone, there is an easy, cheap workaround. You will need a level that reads angles and preferably a ruler to use as a straight edge. Here is an example for about $13 and a pack of rulers if wanted. I like the idea of attaching a ruler as a straight edge along the top of the clinometer to more accurately measure the angle to the top of the pile. Also the groove down the center can be used to look down its length. You may have a ruler at home that you can use as well. By taping the ruler to the bottom of the clinometer and looking down the ruler lengthwise at the top of the pile down the edge of the ruler to take the angle reading. If you are using a bendable ruler (such as many metal rulers) tape it to the back of the clinometer instead, and look down the long edge rather than the long face of the ruler to take the reading.
Calibrate your level
If you’re using a level app on your phone, check the calibration of the level. On a shelf that you’ve checked to be perfectly level with a real spirit level, place your smartphone on its side , then ‘zero’ it (calibrating will usually be an option in the menu, depending on the app).
Data Required for Pile Height
You will need to know three things:
The angle of elevation to the top of the pile from horizontal, measured by your level. You should pick a spot to take the measurement from an area where you can clearly see the top of the pile. While you or your partner stand and measure this angle (looking down the edge of your level directly at the top of the pile) the other should read the angle given by the level for the most accurate reading.
The distance from where you stand to the middle of the pile. Again, make sure from where you stand you can see the top of the pile. You may not be able to measure this distance on- site, but don’t worry, this can be done using Google Maps after you have created a balloon map of the area. In this case, it is important to measure your distance from a clearly visible object (a fence, house, tree etc) so you will be able to identify where you were standing later on, or by standing next to an object like this. If you have an Android phone, you can download an app called Share My Position. There are comparable apps for iPhone as well. This app gives you an exact readout of your latitude and longitude to be used later.
The height of your eye above the ground. Use a tape measure to record not your height, but the distance from the ground to your eye (where the level is).
IMPORTANT NOTE: These measurements work assuming there is not an elevation change between you and the pile. If possible, stand in an area without an elevation change. If you are unsure if there is an elevation change, when using Google Earth later to measure your distance from the pile, use the program to check for an elevation change as well. If you can see the bottom of the pile clearly, there is a way to work around possible elevation changes: the height of your eye measurement can be replaced with another measurement: measure not only the angle from your eye to the top of the pile, but also the angle from your eye to the base of the pile (again, this will only work if the bottom of the pile is also visible).
You’ll use some simple trigonometry to calculate the height of the pile. All you is the measurements taken above, a calculator will do the rest. The equation you will use is:
Pile Height = Tan (angle of elevation x distance to pile) + height of eye
If you do not have a calculator that has a Tan button, use something such as Google’s online calculator.
If you are replacing the height of your eye with the angle to the base of the pile, use the equation below:
Pile Height = [Tan (angle of elevation x distance to pile)] + [Tan (angle to base of pile x distance to pile)]
METHOD FOR DETERMINING AREA AND VOLUME
Once the balloon map has been constructed, the map can be overlayed on Google Earth, where distances can be measured, and the height of the pile can be calculated. Pictures of the pile should be taken to better estimate the shape. Measurements such as the width of the base, area, etc can then be taken using measurements on the balloon map. Depending on the shape of the pile, different measurements may need to be taken. I'll be using this stockpile calculator to estimate the volume of the petcoke piles. The angle of repose (or the the steepest angle at which a sloped surface is formed from loose material) may also need to be known - if the material is the same all the way through, you may be able to find it online, for example the angle of repose for petcoke is 35°.
After we have the volume of the pile, weight can easily be calculated based on the weight per cubic foot of the material. For mixed debris, FEMA has an brochure that details volume/weight estimations. FEMA estimates:
Construction and Demolition Debris: 1 ton = 2 cubic yards Mixed Debris: 1 ton = 4 cubic yards Vegetative Debris: Hardwoods: 1 ton = 4 cubic yards Softwoods: 1 ton = 6 cubic yards
Questions and next steps
The group is also interested in performing a spectral analysis of the petcoke - it is known that petcoke is 90% carbon, but the other 10% is not known. Since the piles are stored in the open air and have been blown around the neighborhood, respiratory health concerns have been raised by the community. The group is investigating methods for analyzing samples.
Why I'm interested
This method will hopefully be able to show how much petcoke is being stored in the area, and used to demonstrate the need for covering, moving, or reducing the size of the piles. With the addition of spectral analysis, the volume of harmful substances in the area such as heavy metals could be demonstrated. Also if multiple maps are constructed, the changing volume of the piles could be tracked by the communiity.