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Sampling Platforms
Because the SET measures elevation change of soft, unconsolidated wetland sediments, you need to minimize your impact to the immediate area around the benchmark you install. This is usually accomplished by constructing a sampling platform. A sampling platform can be either temporary or permanent.
Temporary or Portable Platforms
Permanent Platforms
Delta NWR, LA USA
Permanent Platform - Delta NWR, Venice, Louisiana

Temporary or Portable Sampling Platforms:
Portable Platform Temp Platform 1

There are situations where you may not be able to use a permanent sampling platform and a temporary platform may be the right choice. Portable platforms do not stay on site like a permanent platform. They are carried out for the sampling then removed when you are finished.

Reasons for a temporary platform:
a) Some managers or agencies may not allow permanent platforms.
b) Some study areas are remote and logistically difficult to transport the lumber to and build.
c) A permanent platform may be too visible and attract unwanted attention to your site.
d) Cost of the wood and supplies.

These circumstances may result in the use of a portable platform. A portable platform consists of one or two wooden (or aluminum) planks with "milk crates" or "step stools" taped to the bottom to elevate the planks above the marsh surface. The step-stools will have small boards bolted to the bottom to keep the legs from piercing the soil (see photos below). Planks are usually about 10' (2"x10"x10' or 2"x8"x10') in length. We now use Aluminum Bleacher seats (9.5" wide) instead of a wooden plank. This results in a lighter platform which is relatively easy to transport.

For portable platforms to be successful, the site has to have relatively firm sediments. You also need to mark the boundaries of your study area with stakes to delineate where you need to use the plank. We typically stake the area around the SET with fiberglass or pvc stakes.


Design
Platform Platform
Steward B. McKinney Refuge, CT, USA Blackwater NWR, MD, USA
Fire Island NS, NY USA Rachel Carson NWR, ME USA

Permanent Sampling Platforms:

 

Sampling Platform 1
Platform
Permanent Platform - crevass pond
Delta NWR, Louisiana, USA
Permanent Platform - brackish marsh
Edgewater, MD, USA
salt marsh
Rachel Carson NWR, Maine, USA
mangrove, saltmarsh
Jervis Bay, NSW, Australia

 

Design:
Permanent Platforms are usually constructed out of treated lumber consisting of 2 planks (2"x10"x8' or 2"x10"x10') supported by 2 “teeth” which are pounded into the ground. The teeth are constructed out of 2, 2x4's bolted to a 32" crosspiece. The crosspiece is made out of a 2x4 or a 2x6.

Tooth Diagram

The length of the legs on the teeth will vary depending on where you are installing them. In shallow ponds or in unconsolidated sediments, you may need 8' long legs. You may also need to add a second crosspiece to the tooth to stabilize it further. In firm or very firm marshes, you will need legs 4' or less. Be sure to have the 2 vertical legs stick up above the crosspiece a few inches. This will provide a guide to keep the planks from sliding off the tooth.

The 2 planks on a platform are spaced about 8 feet apart (See below diagram). A third plank (10' is ideal) is laid across the other 2 planks to access the area around the SET pipe. The platform is laid out with the SET sampling sites located between the two planks. Feldspar plots, if used, are located around the outside of the platform.

Platform Diagram

NOTE: The deep and Shallow RSET's are smaller and requires less platform area than the original design SET. The above instructions are for the original SET. You can scale down these platforms and still have plenty of room for the rod SET.

Installation:

Planks in Airboat
McFaddin NWR, TX USA- Note planks in airboat
Teeth in Airboat
McFaddin NWR, TX USA - Note Teeth in airboat
Step 1 - Install the Front Two Teeth
Step 1
Insert the front two teeth. They will be about 6-8 feet apart. Use a sledgehammer to knock them into the substrate. Crosspieces should be about 1-2 feet above the surface. Possibly higher if you are in a pond.
Step 1 photo
McFaddin NWR, Texas USA
Step 2 - Lay Planks
Step 2
Lay planks on each tooth. The far end of the plank will be laying on the marsh (or on the pond bottom). Make sure they are perpendicular to the tooth.
Sledgeman
Tijuana Slough NWR,CA USA
Step 3 - Install the Back Teeth
Step 3
Walk out onto the plank with a tooth in your hands ready to install. Be careful, this is a tricky maneuver and you may be likely to slip. Have another person steady the board you are walking on. This same person can pass you the sledgehammer once you're at the end of the plank. While standing on the plank, knock the far tooth into the ground. Do the same for the other side. All four teeth are now in the ground.
Step 3 photo
Step 3 photo
Everglades National Park, FL USA
Step 4 - Finished
Step 4

Walk back to the end of the plank and step off. Pull the board back and lay it on top of the far tooth. You are finished!

Bolts: Be sure to tighten the bolts on the crosspieces after the platform is assembled.

Planks: If you are leaving the planks on the platform, you might consider nailing them down. This will keep them from floating away and getting stolen (hopefully).

Finished Platform
McFaddin NWR, TX USA
Tighten Bolts
Everglades NP, FL USA