The project, called the Urban Prospector, is basically a modified metal detector outfitted with a combustible gas sensor that can be built for under 100 dollars. By scanning the surface of your neighborhood, you will be able to determine pockets of oil and other toxins.

Until recently, oil prospecting has been a field left to the professionals because it requires sophisticated tools for detection. But in much the same way gold prospecting empowered people to find small nuggets of profit, urban prospectors now have the potential to find small nuggets of oil near oil spills, abandoned gas stations, and industrial sites. Given the current high cost of oil, these urban spills or potential gold mines are waiting to be tapped.*-

Go to UrbanProspecting.net for more info.
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Step 1: Compile Materials

For this project you will need:

-TIF 8800 combustible gas detector http://www.tequipment.net/TIFTIF8800.asp
-Used metal detector (this can be ordered from ebay.com)
-Soldering iron and solder
-2 colors of 24 gauge wire
-electronics screwdriver kit
-hot glue gun
-wire cutters
-vice and pliers
-Dremel rotary tool

Using a used metal detector found at on ebay, one can remove the metal sensor and replace it with a combustible gas sensor. So, to get started on your own Urban Prospecting Detector you will first need to compile the materials and equipment specified in the list above.

Step 2: Disassemble TIF 8800

Start by opening up the TIF 8800 combustible gas detector to reveal the inside circuit board (to open it you will have to pull off the sensitivity pot on the face of the device). Once opened, pop off the red plastic tabs that would release the circuit board.

Step 3: Snip the Sensor and Battery Compartment Wires

After you have opened it, continue by snipping the wires to the battery compartment (red and white), and sensor (blue, black, and white).

Step 4: Remove the Sensor

Remove the sensor at the tip of the metal arm. You may need to use the pliers and vice grip to remove this. Once loosened, you will be able to pull the sensor out of the metal arm with the wires. Once the sensor is removed you can break the metal arm off of the device. Then use a saw and cut out the battery compartment for later use.

Step 5: Remove Pot and Switch

To remove the switch, use your wire cutters to snip the attachments on top side. Then, heat the solder on each connection and pull out the switch. You may need to remove some solder with a solder braid. The pot can be removed also by heating the solder on the connections and pulling them out. Remove the battery casing and power input in the same manner.

Step 6: Extending Components

Use about 5 inches of 24 gauge wire to extend the pot, switch, battery casing, and power input away from the circuit board. Use about 3 feet of wire to extend the sensor away from the circuit board. Now put the circuit board and components to the side as we move onto the metal detector casing.

Step 7: Adding LEDs

What good is your newly built metal detector without a little bling? In this step you should add some (type of LEDs) to (the section that the LEDs should be soldered to). You can hot glue them to the assigned hole and then wire them to the ground and power on your components. In this example I used green LEDs, but you can choose any color you like.

Step 8: Disassemble Metal Detector

Using your dremel rotary tool, drill out the holes for the pots, switches and LEDs on the front cover of the metal detector.

Step 9: Remove and Disassemble Metal Detector Sensor

The casing of the metal detector sensor will also hold the combustible gas sensor that you removed previously. But first we have to remove the coils from inside the sensor and to drill an appropriate sized hole through the middle of the sensor casing.

Step 10: Insert the Sensor and Circuit Board

Now that you have affixed all of the components properly, it is simply a matter of inserting the circuit board into the casing and each component into its designated hole. Place the the circuit board on wooden rails to prevent it from grounding out on the metal casing. Then hot glue the speaker and the battery compartment in the casing as well.

Step 11: Take It for a Test Ride!

You have now completed your very own Urban Prospecting Detector and are well on your way to discovering the riches that lay beneath us. The final step is to go out and find your local neighborhood's black gold mine.