19a — Underground Pipe System for Plant Irrigation

Chapter 19, Section 2 of the House Manual explains the use of water for plant irrigation.

This Chapter 19a explains which components make up the plant irrigation system, where they are located, how these components are connected, and how they can be used, e.g., by turning them on and off.

The information in this chapter is only intended
● for gardeners, and
● for those long-stay tenants who want to actively contribute to the care of the private or community garden, mainly for plant irrigation particularly during the long dry season from November to April/May, and also
● for tenants who want to use a planter bed to grow their own vegetables and herbs.

The following map shows the main components of the plant irrigation system.

The main components of the plant irrigation system:
ditches and ponds, one deep well with a submersible pump (SM), two water pumps (P1, P2), underground PVC pipe system (Main Lines E in blue, C in orange, W in red, and S in green)

The main components are as follows:

• The public ditch or canal along the western and southern border of Baan Sammi. The water flow direction in this ditch is from northwest to southeast. The ditch does not carry water all year round. The flow of water into this ditch is regulated by an authority and depends on the water availability in the reservoir and the water requirements of the rice fields connected to the ditch. Especially in the dry season, the ditch may not contain water for a long time.
• The small pond ("Pond South"), located in the southeastern corner of the Baan Sammi property. This is the only pond being connected to the public ditch in the south, thus enabling unregulated water inflow from that ditch.
• A small pond ("Pond East"), that is farther extended by a ditch to the two northern ponds, and by a side ditch to the large natural swimming pond, Dragon's Paddling Pool.
• The deep well (bore), over 100 m deep with a submersible pump ("SM"), located next to the driveway and between Pond South and Pond West, and with a pipe outflow to each of these two ponds.
• Two constant pressure water pumps ("P1" and "P2") for plant irrigation: Pump 1 with inflow pipe from Pond South; Pump 2 with inflow pipe from both, Pond South and Pond East.
• The underground PVC pipe system for irrigation, consisting of 4 main lines: Line East ("E", blue on the map), Central ("C", orange), West ("W", red), and South ("S", green). The Main Lines East, Central, and West are connected to both pumps, and the Main Line South is connected to Pump 1 only.

Not shown on the map are the numerous main sublines with their outflow taps of the four main lines of the underground pipe system. How these irrigation outflow taps can be recognized (and not be confused with village water outflow taps providing drinkable water) is explained in the aforementioned Chapter 19, Section 2.

Explanation of the functions of the main components for irrigation:

• Water runs in the public ditch for most of the year. During the dry season, the flow of water may be temporarily stopped for a few weeks or even longer than a month, and the ditch may dry out.
• Generally, the water from Pond South is used for irrigation, provided the water level is sufficient. The water level is insufficient if it decreases lower than the pipe end for water inflow to Pump 2, which can happen if the public ditch runs out of water. In this case, Pond South needs to be filled with groundwater from the deep well by the submersible pump.
• Occasionally, the water from Pond East can be used for irrigation, provided the water level is sufficient. The water level is insufficient if it decreases lower than the pipe end for water inflow to Pump 2, which may happen naturally over a couple of weeks, mainly during the dry season. In this case, Pond East needs to be filled with groundwater from the deep well by the submersible pump.
• The water from the deep well (bore) is pumped up by the submersible pump for the only purpose to raise the water level of the ponds.
• Irrigation can start when, firstly, Pump 2 (or/and Pump 1) will be switched on and, secondly, the main taps (next to the pumps) regulating the water flow for the three/four main lines are opened (not the other way round!). Irrigation can stop when, firstly, the main taps are closed, and, secondly, the switch for Pump 2 (or/and Pump 1) is switched off (not the other way round!).
• On the main outflow pipe of Pump 2, each particular main line (E, C, and W) can be regulated independently by turning on or off the relevant tap. On the main outflow pipe of Pump 1, each particular main line (E, C, W, and S) can be regulated independently by turning on or off the relevant tap. As three main lines, E, C, and W are connected with both pumps, the taps for E, C, and W can be turned on at one pump but must be turned off at the other pump.
• On Pump 1, there is an additional (second) outflow pipe with a tap, but it is not connected to an underground line. This tap can be turned on for extra water flow, so the pump can work uninterrupted.
• On Pump 1, there is a half-inch PVC underground pipe with a tap that connects to the outflow pipe of the pump. This half-inch pipe bears the words "village" next to its tap, and it is connected to the village's tap water supply system. This tap must remain permanently turned off. Only in the very rare case where all the pumps are out of work for days and some plants in the garden need drip irrigation to help them survive a long drought, this tap can be turned on to water the plants with village water for a limited time.

The standard operation mode of irrigation is by using Pump 2 with water from Pond South. The starting and finishing irrigation of this mode is explained below. Any other mode, e.g., using Pump 1 instead, is similar but not further explained here.

How to start irrigation using the Main Lines E, C, W, and Pump 2 with water from Pond South?

1. Go to Pond South: Check out if the water level in Pond South is sufficiently high.
2. Go to Pump 1(!): Check out the main taps of the Main Lines E, C, W, and S at Pump 1: all taps must be closed.
3. Go to Pump 2. The water inflow tap for Pump 2 should be opened for Pond South and closed for Pond West (standard operation mode).
4. Switch on Pump 2.
5. Turn on the main taps of the Main Lines E, C, or/and W.
6. Now, water flows in the pipes of the main lines and sublines to the outflow taps.
7. Go and open any of the outflow taps of the main lines/sublines, and you can start with the irrigation of plants.

How to stop or finish irrigation using Main Lines E, C, W, and Pump 2 with water from Pond South?

1. To stop irrigation just for a while at a particular outflow tap, you merely need to turn off that opened outflow tap.
2. To finish irrigation for the day, you first need to turn off all outflow taps and secondly the main taps for all three Main Lines E, C, and W at Pump 2.
3. Pump 2 should have stopped working.
4. Thereafter, switch off Pump 2 (NEVER the other way round: switching off the pump and then turning off taps).

How to let flow water from the deep well into Pond South?

• Be aware that one of the two outflow taps of the deep well pipe must ALWAYS be turned on, meaning water can potentially flow through that tap. NEVER TURN OFF BOTH OUTFLOW TAPS! If this happens and the submersible pump will be switched on, extreme damage can be the result. One damage can be the overheating of the submersible pump followed by the burning and melting of its internal wiring. Thus, the PVC pipes together with the submersible pump have to be removed by pulling up step by step, and the pump replaced by a new one. Costs will be around 50,000 Baht. Even more severe damage can occur when the PVC pipe, which leads down to the submersible pump, bursts from water pressure. Then it might be impossible to remove the pipes from the borehole, and a new bore next to the existing one must be drilled. Costs may reach 400,000 Baht.

1. Check if the outflow tap of the deep well pipe towards Pond South is turned on.
2. If it is turned off, turn it on and then turn off the outflow tap of the pipe towards Pond East.
3. Thereafter, switch on the submersible pump, and, after a few seconds' delay, water from the deep well will flow into Pond South.
4. When this pond has reached the higher water level wanted, switch off the submersible pump, but DON'T TURN OFF THE OUTFLOW TAP.

Deep well

Deep well:
Tap (turned on) of outflow pipe to Pond East (left).
Tap (turned off) of outflow pipe to Pond South (right)

Pump hut with Pump 1 (P1)

Pump hut with Pump 1 (P1), from left to right:
Pump 1, showing outflow pipe with main tap on the left and inflow pipe on the right;
outflow pipe, connecting to 5 underground main lines E, C, W, and S, each with a tap, and with an additional tap that connects to village tap water;
a second outlet of the pump, with a tap but not connected to an underground line;
the switch for Pump 1

Pump hut with Pump 2 (P2)

Pump hut with Pump 2 (P2), from left to right:
inflow pipe from Pond S and Pond E, each with a tap (left tap is turned on, right off);
outflow pipe, connecting to underground main line E;
outflow pipes, connecting to underground main lines W and C;
switches are in the right gray box that can be opened: the left switch for the submersible pump, the right switch for the Pump 2