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Dipwell installation guide A dipwell (PVC pipe) is used to measure the water table depth in peat soils and is also used for measuring subsidence when the dipwell is installed into the mineral soil. Materials / Equipment required

Perforated PVC pipes

Non-perforated PVC pipes

Additional equipment: Measuring tape, gloves, hacksaw, compass, GPS, permanent markers, notebook & pen

Soil auger

Connector

Glue

Cap Collar

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How to install a dipwell and measure peat thickness

1.

- Identify a suitable location for the dipwell. In forest install the dipwell in the hollow (not in the hummock!) - Place planks around the area of interest, to avoid too much disturbance, the dipwell location is not only used for measuring groundwater depth but also subsidence (i.e. lowering of the peat surface). - If needed, clear the area of vegetation before starting the augering. Only clear the vegetation which is

hampering the augering.

2.

- All activities within the area of interest are to be conducted on the planks to reduce pressure on the

peat soil - Place the auger on the peat surface and turn in a clockwise direction. The auger must be perpendicular

to the peat surface of around the augering point. - The peat soil collected gradually while augering will be used for filling the gaps later. Augering should

be carried out gently to minimize damage/widening of gap.

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3.

Augering can be carried out by one person but to decouple (to extend or reduce the length), it is best to be handled by two people– one to hold to lower part of the auger (to prevent it from falling into the hole) while the other removes the connector.

4.

- Augering is carried out until the augur reaches the mineral base of the peat soil. - Measurement of mineral soil trapped in the auger is measured for calculating the peat thickness later.

5.

- Before removing the auger, measure the length of the auger protruding from the peat surface which is to be used in calculating peat thickness.

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6.

- PVC pipes are then measured and cut into size to be inserted into the hole. The top few meters of the pipe is perforated with small holes to allow water to enter the pipe. - The open end of the bottom pipe is to be covered before inserting it into the hole, preventing peat soil material from the side of the auger hole to enter the pipe, until it reaches the mineral base.

7.

Gently, back-fill the hole with the soil collected during augering.

8.

- After the installation is complete, a collar is placed on the peat soil which is used as a reference base for all future measurements, and a cap is put on the pipe to prevent rainwater from entering the pipe

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which might affect the results if readings were taken on/after a rainy day. - Write the name of the dipwell on the cap with a permanent marker, and the position of the dipwell measured by GPS for the purposes of making data bases.

How to measure groundwater levels

1.

Take note of the starting point on the stick. Stick should be straight and also dry before it is inserted into the dipwell.

2.

The stick is inserted into the dipwell until it reaches the water.

3.

Measure the length from the starting point to the point where water is recorded.

4.

Measure the length of the protruding pipe.

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Illustration for measuring peat thickness and water table level

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Calculation formula 1. Calculation formula for peat thickness: Overall length of auger (From handle until it reaches mineral soil) = W Peat thickness = Y Part of auger not in soil = X Mineral soil = Z Y = W – Z – X Example: Length of auger with extensions = 7.35 m Length of auger protruding from soil surface= 0.60 m Measurement of mineral soil = 0.10 m Peat thickness = 7.35 m – 0.60 m – 0.10 m = 6.65 m 2. Calculation formula for groundwater table level: Groundwater table level = Z Length of measuring stick until water table level = Y Height of pipe protruding from the soil = x Z = Y – X Example: Measurement of water table level = 1.27 m Length of pipe protruding from soil = 0.40 m Water table level = 0.87 m