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Installing Deep Benchmarks:

The below page will give you detailed instructions for installing the deep benchmarks for use with the RSET.

Please be aware that there are two slightly different setups for the deep benchmark. Differences are noted below.

Rod SET on deep benchmark
Blackwater NWR, Maryland		 Rod SET - Blackwater NWR, MD USA
Blackwater NWR, Cambridge, MD

The general procedure for installing deep benchmarks is as follows:

a) Build a platform
b) Drive the Stainless Steel Rods into the ground
c) Original Installation: Cement the rod in place.
     Modified Installation: Cut the ROD, attach the receiver and cement in place.
d) Take your baseline SET reading.
e) Lay out your Marker Horizons (optional).

Below are details on specific installations
Supplies:

1) Rod SET - the instrument - Costs run about $700 each.

Original Installation:
2) Collars - These are custom built out of stainless steel. Cost about $30-40 each.

Modified Installation:
2) Receivers/Insert Collar - Custom built out of stainless steel. Receivers are expensive and will cost about $80-90 each. The insert collar is about $150-200. You only need one insert collar.

3) CEMENT - Expansion or Hydraulic cement works great but the standard mortar mix also works fine. It's probably more economical to use regular cement or mortar mix since you will need to fill the 6" PVC pipe.

4) RODS - We use 9/16" Stainless Steel Rods which come in 4 feet long sections (ends are threaded). Cost per Rod is about $15-25 PER SECTION.

SS Rods
SS Rods
Threaded coupling
Threaded coupling

Depending on the environment, these rods will be driven into the substrate to a depth ranging from 6-75 ft (2-25m).You can also order driving tips which are short pieces of SS rod with a point on the end.

Driving Tip
Driving Tip

5) Cement tools and bucket, paper towels, duct tape.

6) Brass Concrete marker - These are 2" diameter brass markers which we stamp with an ID number. They are inserted into the cement before it hardens and serve as a site marker. They can also serve as a survey benchmark.

Concrete Marker
Brass Concrete Marker
 Concrete Marker

7) Pounder - For driving the rods into the ground. We had a custom pounder made just for driving these rods into the marsh. It's much safer to use a pounder than to use a sledgehammer.

Rod Pounder
Rod Pounder

8) Driving head - Attaches to the topmost SS Rod. It takes the blows from the Pounder or Sledge. It's mainly used to protect the SS rods from getting deformed. You can usually use an old cut piece of SS rod for this. It needs to have threads on one end so it can couple with the rods. A 2' long piece works very well.

SS Driving Head
Driving Head

9) Post hole digger and/or sharp shooter shovel.

10) 4" or 6" diameter PVC pipe - about 24" long (Use 6" PVC pipe if you are using the receiver).

11) New Method Only: Bolt Cutter or Hacksaw - We use a hydraulic bolt cutter (Expensive ~$800) to cut the SS rods. This is the only way to easily cut these rods. They are EXTREMELY difficult to cut by any other means. A hacksaw will work but will take a long time.

Hydraulic Bolt Cutters
Hydraulic Bolt Cutter

12) Marker horizons. We use feldspar or sand. Need a respirator mask for feldspar. Put this out when you take your first SET readings (Baseline), not before!

13) ½" pvc pipe - for marking the boundaries of the feldspar plots.

A) Build the platform:

Click here for a details on platform construction

B) Installing the SET benchmark rod:

1) Using a post-hole digger and/or shovel, dig a hole about 4" or 6" in diameter (the diameter of your PVC pipe). Try to make it about 1-2 feet deep. Remove the soil in the hole from the immediate area in a bucket. It's OK if the PVC pipe is longer than the hole is deep. You can drive the pipe with a sledge into the underlying substrate. It helps to anchor the benchmark.

2) Screw together about 2 or 3 sections of rod together. Install the tip on the leading edge (if you have one). Make sure connections are tight.

3) Make sure it's vertical and push the rod into the hole and into the ground by hand.

4) Attach the driving head (Photo) and the slide the pounder over the top of the rod.

5) Pound the rods into the ground. Add sections and continue until refusal or you hit bedrock. While pounding be sure to keep screwing the rods together. You can use a pair of vice grips to grab the rod and tighten the connections as you drive the rod in.

NOTE: Be sure to keep an accurate count of rods. It's easy to get confused and lose track of how many you've sunk.

C) Cement the benchmark ROD in place:
Follow the appropriate directions for your installation

Original Method:using collars only

6) Make sure you have about 1 - 2 feet of rod sticking above the surface because this is what the collar will attach to.

7) Drive the 4" or 6" PVC pipe into the hole. Use a small sledge to knock it down. Try to get it into the sediments beyond the bottom of the hole so it will be stable. Have the top of the PVC pipe stick up about 2-4" above the surface.

8) Fill the hole with cement.

9) Make sure the rod is clean and attach the collar. Leave about 6" of rod protruding above the collar. Tighten the collar in place with a hex-wrench. We have also used Loc-Tite Threadlocker #262 on the threads of the set screws to help lock everything in place.

Rod and Collar

10) You are finished.

New Method:using the "receiver"
NOTE: this is the method we now use in all new installations.

6) Using the hydraulic bolt cutter (or hacksaw), cut the rod off at the marsh surface.

Bolt Cutter
Hydraulic Bolt Cutter		 Bolt Cutter

If you are using the bolt cutter, have someone hold the top piece as you cut it. Otherwise, it will be launched into the air and could be a hazard.

7) Drive the 6" PVC pipe into the hole. Use a small sledge to knock it down. Try to get it into the below sediments beyond the bottom of the hole so it will be stable. Have the top of the PVC pipe stick up about 2-4" above the surface.

PVC Pipe
Gateway NRA, Sandy Hook, NJ USA

8) Slide the SS receiver over the rod and into the hole. Tighten the bolts on the receiver. This will attach it to the deep rod.

NOTE: you can attach the Receiver prior to driving the PVC pipe into the substrate.

Receiver and PVC pipe
 Receiver attached to SS rod

9) Fill the PVC pipe with cement (mortar mix). Regular cement works fine but you can also use the quick drying expansion (or hydraulic) cement to do this. Work quickly if it's the fast drying stuff.

10) If you are using a brass concrete marker, place it into the cement before it sets

Concrete Marker
Concrete marker
 Rod SET

 

10) You are finished

D) Step 4 - Take your baseline SET reading.

Click here for details on how to take the first readings.


E) Step 5 - Lay out your Marker Horizon (optional)

Click here for instructions on how to establish the marker horizons.

U.S. Department of the Interior, U.S. Geological Survey,
Patuxent Wildlife Research Center | URL: http://www.pwrc.usgs.gov/
Last Updated: 14 February 2003
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