Monday, 29 June 2009

One-Person Water Level

As an antidote to the recent rounds of gripes and groans, here is a water level I built on the weekend, with instructions on reproducing it. This is an upgrade from one I built a long time ago out of a juice bottle, a lump of wood and some clear tubing. It's from a design my mother passed on to me, though I'm not sure that her mother passed it on to her...

To begin, you need some materials:
  • A water drum with a tap, or similar vessel. It needs a tap because this is the advanced version. If you want to build a simple one, any old water container will do, though it needs to be big enough to hold enough water to fill the piping you use and then some.
  • A length of clear plastic hose. I went for 12mm diameter hose, 2m of it. This matches up to standard 13mm irrigation fittings, making the whole project possible. If you go with a different size hose you'll need different fittings.
  • A length of wood for your staff. I made mine out of a 2.3m length of 70mm x 20mm pine, trimmed back to 2.2m as my length of tubing was only 2m. No point carrying around extra wood :-) I routed the edges to make it easier to hold, and to look at, then gave it a few soaking coats of linseed oil to help preserve it.
  • A length of old measuring tape. You can skip this bit, especially if you are only using the level to create, well, levels, rather than to measure contours etc. I took mine from an old 30m reel tape that had lost it's end, the cloth tape is easy to work with. You could use a bit of old metal tape measure if you desire, but be careful cutting it!
  • Some pipe clamps, 3 or 4 saddle clamps, a couple of short lengths of 13mm irrigation pipe, a 13mm elbow joiner, and two 13mm to garden hose couplers.
  • Suitable length of garden hose with couplers. I got a 15m garden hose with fittings for $8 from the local super-hardware. I could have as easily used the one in the garden, but the DW might have gotten a bit upset if it wasn't returned promptly, so I thought it best to spend the extra to get a dedicated one. The beauty of this design is that you can couple as many hoses together as you want to make the main line, all for a lot less expense than buying clear hose for the full unit. Just be careful your drum is big enough to fill the hose and then some, and that there are no leaks along the way.

Putting it together...
  1. Starting with the drum. Take a short length of the 13mm tube and connect one of the hose couplers to it and clamp in place. Then push the other end over the outlet on the tap of your drum and clamp it as well (make sure you put the clamp on the hose before pushing into place!) The drum is now ready to go. In the picture below there is a cover over the end of the hose coupling, so it might not look exactly as you'd expect.
  2. Taking your plastic tubing, thread a clamp on, then insert the elbow, securing it with the clamp. Push a short piece of 13mm irrigation pipe (6cm or so, just long enough to cover the ends of the two fittings with a slight gap between) onto the elbow, clamp in place, thread your next clamp on then insert your other hose coupler and clamp in place. This is now the bottom of the tube. The open end is the top.
  3. After preparing your wood for the staff, if you're going to use a tape, thumbtack this (if cloth tape, screw if metal) towards the outside edge of the face of the staff, leaving some space at the top and bottom.
  4. Screw, with a large flat headed screw, the top of the clear tubing at the top of the staff, as close to the centreline of the face as possible (doesn't need to be exact of course, unless you're particular) You should make sure there is 10mm - 20mm of tube above the screw so that it wont tear out too easily. When screwing it on you don't want to completely seal the top of the tube, you need to allow air in and out to allow the water to level. A firm but not overly tight connection is best. Also try to make sure the elbow and coupler at the bottom is facing outward from the staff face before you screw the pipe in place.
  5. Straighten your tubing out down the length of the staff, space your saddle clamps out and drill some pilot holes, then screw the clamps down over the tubing. You want to make sure your last clamp is right down on the elbow installed previously so that it helps to stretch the tubing out nice and straight.
  6. You're finished the construction stage!
Using the level... Preparation
  1. Turn the tap on your drum off, then fill it with water.
  2. Place your drum in a slightly elevated position near where you want to take your levels or work out your contours. You'll need a fairly rugged stand due to the weight of the water in the drum, so a toolbox, garden chair or something similar. Keep in mind that the height of the drum helps dictate the height of the water in your staff.
  3. Plug one end of your garden hose onto the drum. Plug the other end onto your staff.
  4. Making sure you've got a grip on the staff (nothing worse than the staff falling over and draining when you're miles away from a source of water) open the tap on the drum, and loosen the lid to let some air in.
  5. Walk around with the staff, not only for the exercise, but to help get the bubbles out of the water in the piping. Your staff is now ready to put to work.
Using the level... In Action - Levelling
  1. Pick the spot you want to level everything else to. This is ground zero.
  2. Place your staff on that spot. With a pencil mark the height the water comes up to on the staff.
  3. Place the staff in another spot. If the water rises above your previous mark then you're lower down. If it sinks below the previous mark then you're higher up. You can tell by how much if you've attached a tape to the staff by reading off the difference in centimetres (or inches if you put your tape on that way around!) between the first and second marks. When the water is at the same mark then you're at exactly the same level. Great for setting up concreting, paving etc.
Using the level... In Action - Contours
  1. For measuring contours we need to do a bit more preparation, namely measuring out a grid on the ground. Something like 5m intervals is good if you want a reasonable picture of your plot of ground. 1m grid if it's a small spot and you need incredible detail. 10, 20, 50 if you're less enthused about the idea of contour maps than I. You need to do your best to make sure your grid is as square as possible.
  2. You can also measure at intervals along structures such as fences and buildings, and between points. The key, with either grids or features, is to be able to place the measured point on a map back in the "lab".
  3. Once you've marked out the spots you want to measure you then run around with the staff. Pick the highest point as zero (or the lowest, or any old point, as long as you record which one it was) and mark it on your staff, then record each spot as a value below or above that (so -5cm, or +8cm) for each of your points.
  4. Hopefully you included enough lengths of hose to get you around the whole job without moving your water drum, but there are certain occasions when you'll need to move it. Points beyond your reach are one, the other is cases where your slopes are bigger than the height of your staff. If you go below or above that the water drains out and all is lost :-)
  5. If you need to move the drum, mark one point from your current measurements as your new "zero" for the second set of measurements. Once your drum is moved, re-measure that zero spot, make a new mark on the staff and measure all changes relative to that mark. Imagine you are working down a hill, your bottom-most mark is at -0.9m from your original zero. You move the drum so that this mark is now 0.0m (the new zero.) The next measurement you take is 10cm below this (-0.1m) Therefore, relative to your initial measurements it's -1.0m.
  6. Once you've completed all your measurements you need to return to the "lab" and set to work analysing your data. Draw your map, mark in your points, and then mark in all the differences in heights. At this stage you need to make amendments for any changes in the location of the drum as described in (5), so that you end up with a series of measurements all relative to your original starting point.
  7. Once you have all your relative height differences, you need to pick a starting height and point. If you're lucky you'll know the height of somewhere upon your property, relative to sea level (via topo maps etc) if not, pick any arbitrary value, much higher than the difference between your lowest and highest measurements. If your difference is less than 20m then you can safely select 20m and work from there for example.
  8. Add or subtract each value from that 20m successively across your grid of points, pencilling them into your map.
  9. Once this is done you can either roughly guess your crossing points, or you can calculate them using trigonometry. Lets say we have two points 5m apart, one point is 24.4m, the next is 25.2m. We know that somewhere on that line the 25m contour passes over. 25.2m - 24.4m is 0.8m. We can divide the 5m into 8 parts, and mark in that the 25m contour passes 2 parts short of the 25.2m point, or about 1.25 back (or alternately, 6 parts ahead of the 24.4m point, 3.75m ahead)
  10. We can also use a fancy formula that gives us the same result: distance = (rise to meet contour x original run) / original rise. So distance = (0.6m x 5m) / 0.8m = 3.75m so our 25m contour is 3.75m from the 24.4m point.
  11. That's all there is to it. Calculate where all your proper contour points are then play join the dots!

1 comment:

DamntheMatrix said...

Hi... what a great resource!

I also JUST noticed you have a link to my blog, damnthematrix....... what a small world it is, and how great it also is we can share such great info. As you may know, I am about to start building our next house in Tasmania, and digging the foundations start in a month, when the level will really come in handy...

Keep up the good work, and thanks....