Specifications - LYSIMETERs.docx

Minimum Requirements and Specifications Suction lysimeters and accessories for their operation

Background:

We are conducting field studies to optimize and assess managed aquifer recharge approaches. These studies involve the use suction lysimeters in the field to a depth of 75 m to sample soil water so that it can be analyzed for contaminants.

The suction lysimeters should be:

· Durable and reliable for long-term field operation under variably-saturated water flow conditions (from near field capacity to saturation)

· Installed to a depth up to 75 m in the vadose zone

· Maintain capillary contact with field soils while still having high permeability for fast response times

· Collect samples of soil water and return water to surface for analysis Specifications and requirements:

• The lysimeter should able to be installed at a depth of 0 to 75 m

• The lysimeter should be made of welded 316 stainless steel to prevent the adhesion of organics and inorganics

• The lysimeter should withstand a high corroding soil environment for the long term for continuous collection of various quality water that contains salt, minerals, nutrients, inorganics, and organic particles.

• The lysimeter should have high-quality porous stainless steel to allow pore fluid flow into the lysimeter at dry to wet soil conditions.

• The lysimeter should be a welded construction with no glue or plastic that can degrade over time.

• The lysimeter should able to withstand at least 0.6 bars of bubbling pressure.

• The lysimeter should only have a 2” outside diameter in order to fit in an 8” diameter monitoring well.

• The lysimeter should have a length of 3.5-4” to have enough surface area to collect the water and install at close depth intervals to minimize interference.

• The lysimeter should have a threaded collar on top to fit a plastic pipe to install in the 8” monitoring well.

• The tubing outlet should be ¼” to accommodate more than 4+ lysimeters and 20+ outlet tubes to the soil surface within the 8” diameter monitoring well which will be instrumented with multiple other sensors.

• The lysimeter should have a specific outlet for vacuum/pressure and fluid return.

• The lysimeter should have a third outlet to check the leak after fabrication and add water directly to the lower porous section of the lysimeter if the porous section has dried out while deployed in the field.

• The lysimeter should be a dual chamber to be able to use at great depth.

• The lysimeter should have two chamber designs with a one-way stainless steel check valve between the two chambers that prevent the backflow of the fluid from the upper chamber into the lower chamber and the soil around the lysimeter. This valve is critical to use large air pressures, i.e., higher than nine psi, to bring the sample to the surface without blowing the air out of the pores in the lower chamber with the porous steel walls.

• The lysimeter should be able to collect water samples from both native soil materials and silica flour filling to be able to install them in the deep and shallow portion of the monitoring network.

• The water samples should be collected using a handpump, foot pump, or electric pump, depending on the sampling time and location.

• The lysimeter should able to collect a sufficient volume of water, i.e., at least 500 ml of water at one time, which is critical to conducting water quality analysis.

• The lysimeter should able to collect water from both saturated and unsaturated soil material.