Variable terrain rain gage stand

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caption = Precip Stand

caption = 2000 era precip stand

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GWS type stand

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Introduction

Precipitation stands for the rain gages and alter shields have evolved over time. The subject of this wiki is the first picture on the right. A new stand for variable terrain. The second two pictures to the right of the text show the main design used in the 90s and early 2000s. A rain gage is hose clamped to a rebar or several inside the perimeter of the altar shield. The alter shield is secured to two 2x4s crossed and notched. Although a good design for early in the life of the station, over time the shield tends to settle and moves out of the optimal shielding position. In addition, the rebars the precip bucket is connected to tend to move out of level, degrading the measurements.
In 2005 GWS cooked up an alternate stand that uses duckbill anchors and rebars, which was maybe a decent design on paper (picture 4). In the field though, it was a real annoyance to keep level.
At some point Rob Gieck designed the Gieck stand (picture 5). The Gieck stand is a combo of 4 2x6 pieces constructed in an equilateral triangle shape. I haven't worked with the Gieck stand but in 2010 cooked up an alternative suitable for any type of terrain (figure 5 on the right). Although only built so far without alter shields, they would be easy to add on.

Materials

• 1 pcs 10' x 3/4" schedule 40 pipe EMT is not an acceptable substitute. It has too small of a diameter for the nurail fittings
• 2 pcs 3/4" x 3/4" NU-RAIL Crossover Fitting don't expect to find many of these locally, order them from Campbell Scientific or for a better price, go to nurail.com or hollaender.com (linked at bottom of the page)
• 3 pcs 36" or 48" Screed Stake Find these at Home Depot or Alaska Sand and Gravel among other places locally
• 4 pcs #28 Hose Clamp (1-5/16" to 2-1/4" Diameter adjustment range)
• 2 pcs #20 Hose Clamp (1-3/16" to 1-3/4" Diameter adjustment range)

Tools

• Sawzall
• Round File
• Flat File
• 5/16" Nut Driver
• ___ inch allen wrench (Nu-rail fittings use english allen wrenches though I'm not certain the size)
• bubble level
• hand maul or sledge hammer

Procedure

1. In lab, cut 10' pipe to length. You have some flexibility here. For the stands we put in at CPCRW for Bob Bolton & Jessie Cable's Epscor project we cut the adjustment arms to 5' and the vertical pipe for the precip bucket to 30". Bob Bolton thought the 5' was over kill so it could be that a 45" / 45" / 30" setup would work better. For this procedure we'll assume the pipe is indeed cut to 45" / 45" / 30"
2. After cutting the pipe, file off the metal burs with the two files. Use the round file for inside the pipe and the flat file for outside of the pipe.
3. Head to the field.
4. At the site, slide a Nu-Rail fitting over each 45" adjustment arm and then tighten it.
5. Next, slide the precip bucket support leg through the open pipe hole of the Nu-rail fittings and tighten ... but not super tight the allen-head machine screws.
6. Twist the two support arms around the precip support leg until they are roughly perpendicular to each other.
7. Set the apparatus aside and pound a screed stake for the precip support leg into the ground. This screed stake can be pounded until just a few inches are above ground.
8. Next, set the precip support leg adjacent to this first screed stake.
9. Pound the other two screed stakes into the ground. Place them about 6" or so in from the far end of each adjustment arm. Pound the screed stakes until there is 12 to 18 inches of screed stake still above the ground surface... you might choose something different depending on the time of year... as long as you don't pound it to far there shouldn't be a problem.
10. Take two of the #28 hose clamps (the bigger ones) and secure the bottom of the precip support leg to the first screed stake pounded into the ground. The 5/16" nut driver should be the right size for tightening the hose clamps.
11. Mount the precip gage to the precip support leg using the #20 (smaller) hose clamps
12. Remove the anodized aluminum orifice & funnel piece from the rain gage.
13. Set the bubble level on the exposed rim.
14. Raise and lower each adjustment arm until the bubble level shows the precip bucket level in both axes.
15. Use the remaining #28 hose clamps to secure the adjustment arms to their screed stakes.
16. Put the anodized orifice back on the rain gage

Other options

• Although these instructions don't include the addition of an alter shield, one could easily be added... check out the bottom picture. Made these in 2013 for the NGEE project in Barrow. One design I'd do differently from in the picture is to have the precip bucket be on a separate vertical pipe from the anchor pipe. It was difficult to get close to the center of the shield using this method. Maybe the easiest would be to find a supplier for these:
  

106 Dbl. Side Outlet Cross
... and pair that with four of the crossover fittings mentioned above in the materials section. It looks like (from pictures) the alter shields use 3/4" pipe so buy more 3/4" crossover fittings.

• Use this stand for other stuff like radiation / snow depth. Add one more 3/4" cross over fitting and a 5" horizontal pipe. Increase the length of the vertical pipe.