Analysis 2: Exploration Phase- Proposed Pond Excavation Project 2012

The layouts above and below are the result of this analysis. The information shown here is the amount of material  that must be excavated in order to proceed and create a proposed pond. This study was done using both AUTOCAD Map 3D 2012 and ESRI's ArcGIS 2010.

Existing & Proposed Terrain Depth Along Cross Section:

Here's how it is done:

My focus is a small town called Springfield. The top of bank has an elevation of 189.5. The top of bank elevation was set and the study boundary was created using COGO - both procedures were performed in  AutoCAD Map 3D 10.

Provided Data: 

1	Elevation Points
2	Existing Top of Bank with 189.5 Elevation
3	Text File with Study Site Boundary Bearings, Azimuths and Distances
4	Cross Section
5	Elevation at Bottom of Bank with 186.1 Elevation

Below is a layout representation of the provided data. I should note the contour lines were created using the Surface Contours tool of ESRI's 3D Analyst extension. The bottom of bank (Proposed Pond) elevation was set to 186.1 in AutoCAD Map 3D before being imported into ArcMap 10.

 

Proposed Layout: 

Below is a representation of the terrain conditions around and within the proposed pond. The tin (Triangulated Irregular Network) uses a series of triangles created from elevation data. As seen below we then have a representation of the terrain surface for display. 

 

We see the variation in elevation within the proposed pond. From the most Southern position of the proposed pond, the elevation starts at 190- drops to 187, and shoots back up to 191. This variation in terrain elevation is seen in the above Existing & Proposed Terrain Depth graph.

Volume Data: 

In this portion of the study I had the opportunity to use either the Surface Difference Tool or the Cut Fill tool - both from the 3D Analyst extension. The image to the left of the layout below is believed to show the best representation of the site volume, the image to the right, I believe has been incorrectly represented in ESRI. I asked a colleague to run this tool using another set of data and the dark blue triangles showed on both of our images. This speckle could suggest that there is need to fill the site, but the entire study suggests the need to excavate.Therefore, the surface difference tool best represented the amount of material that will be excavated: 20,347.74 meters cubed.

Elevation Volume Curve of Proposed Pond:

The above graph is a representation of volume change. As the elevation in meters increases the volume of the proposed pond increases. Therefore, although the surface difference tool displays the amount of material to excavate (20,347.74 m cubed), the above graph displays the relationship between elevation and volume around the proposed pond.

As originally mentioned, it was visible on the proposed layout that the elevation from the Southern most point of the proposed pond started at 190, dipped to 187 and rose again to 191. The graph indicates that when the elevation increases so will the volume, and as the elevation decreases the volume will follow also. 

 

In relation to cost, we can then assess the cost factor of this project. It could be dependent on area, elevation, or material that will be excavated. With more information, more thorough planning can take place at the exploration stage. 

 

Let's recall:

Data was provided- elevation, proposed pond at 186.1, existing elevation 189.5, surface contours.

A tin created a representative surface using the elevation points.

The volume between the top of bank and bottom of bank was calculated providing us the amount of material to excavate.

A graph of the cross section displays the relationship between elevation and distance along the cross section F-F'.

The study indicates that (20,347.74 m cubed) will be excavated in order to proceed and create the proposed pond.