Correct Hole Placement and Need for Threaded Parts to the System

Q.  I was reading the instructions for automated watering and it says to mark a line and then mark another 30 degrees from that one.  Is it 30 degrees between each line or 45 degrees between each line?  (there are 3 rows of holes in each pipe, right?)

Next, is there any particular reason that the end cap needs to be threaded?  Do you need to take it off for some reason?

How deep are the trenches?  I am guessing that those pipes that go down vertically into the trenches are 1 foot long.  Can they be left in the trenches over winter, without freezing? And, does there need to be a threaded end cap  to allow the water remaining in the pipes down in the trenches, for them to drain–so they won’t freeze over the winter?

PS  I have already purchased all the parts for the system, and I do not have ANYthing with threads on it. 

A.  I apologize that we have two different angles listed for the holes in the PVC pipes.  The 30 degree angle is necessary for narrow beds, such as a 12″ Box.  However, the 45 degree angle is generally more satisfactory, although it shouldn’t make a lot of difference in soil-beds, since the entire planting area is flooded anyway.  In Grow-Boxes, the narrower angle could mean the water isn’t getting very close to the plant roots when the plant is small, and could cause some stress from lack of water, if you don’t make sure of your coverage.

Go back to the store and trade for male threaded ends, female end caps, and threaded ball valves.   Do not make the mistake of building your watering system without having both ends screw off, and the riser from the main line also screwing in (this one is ESPECIALLY important).  And you need to be sure your valve also screws in on both ends.
 
The end cap needs to come off, so that accumulations of stuff in the pipe can be flushed out.  Otherwise, you will begin to have the pipe fill with sediment, or last winter’s critters-seeking-shelter, and watering will suffer greatly.  Also, if it doesn’t screw, the valve up on top can’t be moved out of the way of the tiller or shovel when someone is re-working the bed.
 
If the riser from the main line is glued and someone breaks it, you could easily be faced with an expensive and time-consuming repair job.
 
The valve that controls your water gets a lot of use and abuse, and sometimes there isa break – either in the valved itself or the pipes on either side.  Being able to unscrew it is essential to avoid costly and time consuming repairs.
 
In designing and building your watering system you need to have a stop and waste valve at the low end of the system, so excess water can drain off.  So long as this is done, and your pipes empty themselves before a hard frost, you will have no problem leaving your individual bed risers in the ground over the winter.
 
The trenches for your main line should be more than 8″, since that is the depth of the tillers you will use, and you surely don’t want to be cutting into your main water line.