Monday, August 3, 2015

A Larger Picture of the Bottom part of the West Lawn

The bottom part of the West Lawn is mainly dominated by the big live oak tree.  That and the turn of the River of Rocks, around the corner of the house and over to the steps coming down from the deck.

In trying to define the River of Rocks, it seems that this area slopes downhill quite a bit.  There are big roots for the live oak that run along the ground, and we have had a significant problem of dirt being eroded and washed down into the pool of blue rocks and the Bamboo Grove.

It appears to me that it can be significantly improved by putting in a terrace wall.  A terrace wall would allow me to add dirt to the base of the live oak tree, while at the same time keeping the ground mostly level.  There should be less run-off erosion with level ground.  And the River of Rocks would be able to decrease slowly from the corner of the house to the back deck, rather than decrease a lot and then come back up some.

We thought about building it from 6x6 limestone blocks, like we used for the raised garden, but Linda suggests using natural rock instead.  So we need to come up with a short rock wall of native rock.  A terrace wall of about 24 inches seems like it would work best.

This would partition the bottom part of the West Lawn into two pieces -- upper part around the base of the live oak, and continuing over to the River of Rocks, and a lower part that would stretch from the fence between the Jungle on one side and the terrace wall on the other back to the center of the back yard.

This tongue of yard should be fairly level, from side to side instead of it's current slope down.  We have already excavated the part closest to the fence, but will still need to dig down for most of it.  If we encounter the rocks that we would expect, as we have found in the rest of the yard and in the part near the fence, we should be able to use those big rocks for the terrace wall.  And we need the terrace wall to define the level of the soil behind it, from the terrace wall  around the live oak tree and back up to the main West Lawn.  And we need that level before we can put in the irrigation lines for this section (Zone 8).

So it seems this is the next part of the yard to dig up.  Then define the terrace wall.  Then fill in the ground behind the terrace wall.  Put in the new Zone 8 irrigation lines and heads. Then continue the River of Rocks around the corner of the house to the deck sidewalk.

The Old Irrigation Zone 8

Zone 8 of the irrigation system is sort of the area of the West Lawn.  We are going to re-purpose it so that it is specifically the West Lawn, west of the River of Rocks.  Zone 9 will take care of the beds between the River of Rocks and the house.

All of this area is supposed to be put over to native, drought-resistant, shade tolerant plants.  I think it is sedges and native grasses.  The landscape plan says it is 11, 12, and 13 which are horse herb/wedelia, meadow sedge/texas sedge, and inland sea oats/chili pequin.  I'm assuming that all these have the same watering needs, so I intend to run one line of heads next to the fence, spraying in to the yard, and another line of heads next to the River of Rocks, spraying the other way, so that we cover the entire area.

So the first problem is to remove the old Zone 8 piping.  It seems to go every which way.  Turning on Zone 8 and marking which heads pop up shows a couple along the fence, one by the corner of the house, and a couple in the middle of the yard.  We want to remove all of these, and (eventually) replace them with new piping and heads.

We start with one of the heads.  Dig down and see where the piping is.

We dig along the pipe across the yard, until we get to the River of Rocks.

At this point, it would appear that it runs to a line that runs next to the main irrigation water supply line, which we don't want to disturb, so we cap this line off.

and go on to repeat this for the other heads.

The next group of heads leads us back to the Zone 8 Valve.

which we dig up carefully.

We can see that it is nestled in the turn of the main irrigation supply line.  The main must be one-inch PVC.  Zone 8 taps off of that and sends water in two directions -- one small pipe (1/4 inch) towards the corner of the house, a larger (1/2 inch) pipe goes back to the main supply line and tees into one line going along the main (this is the one that we have capped off all its heads), and another that continues across the yard (which is the one we followed back to find the value).

So we need to dig up this last head for Zone 8, and then clip the existing lines off and attach the lines that will define the new Zone 8, with sea oats and sedges.

As we were digging up the last sprinkler head and PVC line for Zone 8, we had the problem that the Zone 8 line was positioned next to the main irrigation water supply line.  So naturally, we put our pick axe thru the main supply line.

You cannot patch these lines; you have to replace this part.  But replacing a small piece in the middle of an existing line, with both ends fixed in place, is difficult to impossible.  So I replaced a much larger piece, from where the break was down to the corner and up a piece from there.  This includes the section that provides water to the Zone 8 valve, and we decided to move the Zone 8 valve to the outside of the main supply line, instead of it's previous position inside the main supply line.

We replaced the previous Schedule 20 PVC with Schedule 40 PVC, which has much thicker walls.

The main irrigation water supply line is 1.5 inch PVC.  The lines going into and out of the Zone 8 valve are 1 inch PVC.  We will probably end up with two 3/4 inch lines going from the Zone 8 valve, and then step those down to 1/2 inch for the actual heads.

But for now, we are done with this section of the West Lawn, and so we can cover the irrigation lines over, remembering where the Zone 8 valve is, so we can come back to attach to it later.

Continuing the River of Rocks (Part 2)

Continuing the River of Rocks from the A/C compressor down to the corner of the house is a repeat of the first part.  First level the path, and layout the rocks.

Then, each rock has to be individually fitted with a hole suited for that rock, to make it level and stable.

The hard part is trying to see if things are level or not.

And then we add dirt to fill in the spaces between the rocks, and let it sit, to try and settle before we put mondo grass between the rocks.

While we are waiting for this to settle, we can work on the next section of the River of Rocks -- going around the corner, and on the rest of the West Lawn.