Fabrication Improvements for LFOM, Inlet Manifolds, Plate Settlers, Floc Baffles

Each of these units requires creating large diameter holes in PVC pipe or in plastic sheets. The team in Honduras currently uses a hole saw to create these holes. The hole saw creates a rough hole and when the drilling operation is over the "hole" is inside the hole saw and must be removed. The entire process is time consuming. We need a better way to create these holes. The goal is to come up with improved methods of drill holes that can be tested perhaps even at the Marcala plant that is being constructed right now.
Plate settler spacing may be reduced to 1 cm or even 0.5 cm in the near future. In any case we would like to be able to build plate settler modules with reduced spacing to test their effectiveness in a full scale plant (perhaps at Cuatro Comunidades). We need a method to fabricate plate settler modules with very small spacings between plates. It may be possible to use the same fabrication technique as we are using currently or there may be an easier method.
The Inlet Manifold "centipede" design to reduce horizontal velocities in the bottom of the sed tank needs an improved construction technique. Creating a large contact surface area between the 2 inch PVC pipe and the manifold pipe is necessary for a strong bond. In Agalteca we created a large contact area by heating the 2 inch pipes over a wood fire and then while the plastic is soft molding it to the manifold pipe. This suggests that a viable construction technique would be to cut a large hold in the 2 inch pipe using a hole saw, heat the 2 inch pipe to soften it, mold the 2 inch pipe to the inlet manifold, and then glue the 2 inch pipe to the manifold. Experiment with this fabrication technique and develop improvements.

Trash racks for the entrance tank

The new entrance tank that is being designed by the design team will have a place for trash racks. We need a design for these trash racks that can be easily fabricated. The trash racks should ensure that all debris larger than the openings in the linear flow orifice meter are removed. The head loss through the clean trash rack should also be negligible.

Plant flow rate regulation

We need a method for the operator to regulate the flow through the plant that does not close the valve on the transmission line. This is especially important during high turbidity events. The goal is to keep water flowing through the transmission line even if the plant needs to be shut down so that grit doesn't accumulate in the transmission line and so that it is possible to monitor the turbidity coming from the source. That way the operator will know when it is appropriate to put the plant back on line.
The plant flow rate could be controlled by having an adjustable elevation exit weir (to the drain channel). This should be relatively intuitive for the operator because they already know that the water level in the entrance tank is related to the flow through the plant.
How can we create a weir that can have its height easily adjusted over the entire range of the LFOM (20 cm)?

One possibility is to use a reducing flexible coupling. This coupling would connect a smaller pipe that serves as the drain to a larger diameter pipe that serves as the weir. The coupling would slide over the smaller diameter pipe to be adjustable. This might work, but there are probably better approaches.