Think you are ready to purchase that mud system? If you are unsure of your needs, no problem. John Cope with Tri-Flo International takes on the subject of what contractors need to ask themselves before plunking down their money on a new mud system so they can get what best suits their needs.

1. Why do I need a mud system?

Why do I need a recycler, mud cleaner, mud tank, solids control equipment or reclamation system — you know that thing that takes up space, is always covered in mud, and pulls one more man away from doing something else? It saves the contractors’ bottom line. All the other equipment on the jobsite is there to make money and a recycler is there to save money.

2. What size drill do you have?

This is not the time to purchase something marginal, so consider the capabilities of the drill as far as diameters, length of shots and product types that are going to be pulled back. The larger the drill, the more complex system is needed; around 400 gpm is where a reclaimer makes the biggest jump as no longer can the same technology used in lower volume systems remain the same. Multi-staged tanks, larger primary scalping shakers if not two, de-sanders (hydro cyclones of 10 in. or larger) are needed. The cuttings from the cones underflow will be directed onto a vibratory shaker to further de-watering.  The final stage in most systems is a bank of ten to sixteen 4- to 5-in. de-silting hydro cyclones; again the underflow from the cones will flow onto another shaker. This means a large footprint and lots of equipment, which at one time was limited to those companies that made their own equipment. Now with manufacturers building turnkey big drills, more contractors are getting their feet wet. At this level, there is also a need for more personnel to run a reclamation system; it is no longer a one-person show. For the drills 120,000 lbs and smaller, the size of the shakers and number of hydro cyclones will vary from the different manufacturers, but their target range is to cover at least two of the various HDD drills that are being built. Also, keep in mind that most salespeople are also the ones on the front line and the last thing that they want to do is sell a unit that is too small for the customer’s needs. If there is more than one drill in a fleet, use the larger one to size the mud cleaner. It will work on the smaller one just as well.

3. What is my gpm output?

Along with the drill size, the next question to ask yourself is what the gpm output of the pump is either onboard or independent. These come in to play mainly when the back reamer is put on and you are pulling or pushing for all that it’s got. There is a fine line between out running the pump, washing out the bore path or overloading the reclaimer. When using the gpm output, try to use the 1 to 1.5 ratio since both the pumps and reclaimers through-puts are based on clear water specs. When viscosities, solids loading and polymers enter the picture, this ratio will allow some room for the system to keep up.  The gpm and penetration rate are in direct control of solids loading, which should be kept around 10 to 20 percent by weight of solids (like that will happen). A reclamation system needs fluid to work correctly; it is better to have 90 gpm with 18 percent solids than 18 gpm and 60 percent solids. All systems need flowable slurry in order for the cleaning process to work effectively. If the mud in the return pit is above 35 percent solids, it will cause unfavorable conditions for a reclamation system to separate solids effectively.

4. What are your soil conditions?

Some contractors move around where ever the work is located and there are others that remain in certain regions. For those that are on the move, the 1 to 1.5 ratio may grow to 1 to 2 pump gpm/recycler through-put, because of a wider variety of soil conditions that will be encountered. This is also true of the regional companies that drill in sands and clays. If rock is predominately in the region or the movers go for mostly rock jobs, the 1 to 1.5 or 1 to 1.25 ratio would be a good starting point. All manufacturers of solid control equipment will balance the pump sizes to reflect the through-put volume. In regions where fine sands or sugar sand is the predominate soil, de-sanders may be used to take loading off the de-silters.

Regions where clay, sand stone or shale is the majority of soil conditions that are encountered, recyclers with a through-put of 350 gpm and under, the prevalent equipment doing most the work are the de-silters. For the larger drills that can afford the additional cost of a centrifuge, it will help lower the clay build up. It will not take all 100 percent of the flow, but keep the mud weight down to a usable level and lower the percentage of destructive low gravity solids.

5. Rent or Buy?

With the upfront cost for a reclamation system starting at more than a decked out F-350, the first-time user should ask the manufacturer about a lease-to-own or rental. Some of the same lenders that have financed a drill will take care of the mud system also. Renting is especially viable for small drills that only occasionally drill rock and are not pulling back large diameter holes. More often than not, the companies that purchase a solids control system just for the rock jobs seem to start using it like a charge card; they don’t leave home without it.

Sharon M. Bueno is managing editor for Trenchless Technology.

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