Water Well Journal
Issue link: http://read.dmtmag.com/i/715953
waterwelljournal.com 20 September 2016 WWJ While many contractors in the groundwater industry aren't looking for new drilling methods or new slurries, some are looking for new disposal solutions. There are a lot of different options for disposing of drilling spoils, including: ● Hauling liquid waste ● Centrifuge dewatering ● Land/farming applications ● Solidification. Centrifuge dewatering works well, Dugan says, but it can be a costly option best reserved for the largest jobs. You can also pay a company to remove your liquid waste, which can also be expensive. Guardino has tried many different disposal options, but like many contractors, chooses to haul liquid waste. What makes it an affordable choice for him is the ability to spread it out on land. "We are fortunate we have a few ranches where we can dis- pose of the materials," he says. "We oftentimes have people who want to line their stock ponds with the bentonite mud." Bentonite clay is a natural material CETCO mines in Wyoming. Bentonite is a safe product that's also used in the pharmaceutical and cosmetics industries. Plus, anything designed to be put in a water well is National Sanitation Foundation approved. It's an environmentally friendly product, Dugan says, that might even be beneficial for the land. "I've actually talked with the Florida Department of Trans- portation, which is asking to use it along highway easements," he says. "That's because it helps the soil retain moisture and the grass grow." Dugan wants to see more studies on agricultural uses for water well drilling spoils. "I've heard China is restoring depleted farmland with ben- tonite clay," he says. "So it would be interesting to see more studies done on that so we can take this waste product and have more efficient environmental use out of it." But if land spreading isn't an option, solidification can be an option. For example, Dugan worked with contractors on a job in the Florida Everglades on Native American land where drilling spoils were not permitted to come into contact with the surrounding environment. With 16,000 gallons of liquid spoil, it was not financially feasible to haul off the materials. Likewise, finding a facility to take them as a liquid was a challenge. Landfills will take the materials once it becomes a solid waste that passes a paint filter test. You can find standard 60 mesh size paint filters in any home improvement store. If you put a 100 gram or 100 mL sample in the filter for five minutes and any liquid passes through, the material is considered to have free liquids pres- ent—and it's not solid. But, if no liquid passes through, it's a solid waste that can be disposed of in a landfill. Traditional methods of solidifying liquid drilling spoils include mixing it with cement, fly ash, lime, or sawdust. "A lot of people get creative," Dugan says. "They'll mix in anything that could possibly absorb it." These options, while mostly effective in solidifying the material, add volume. This means there is more waste to re- move afterward, which also makes it costlier to remove from the site. On the other hand, bentonite-based blends containing super-absorbent polymers, such as CETCO's Slurrybond products, add little weight to the waste and can allow the waste to be mixed into the soil on site. The powdered inorganic mineral formula is made from non-biodegradable mineral designed specifically for used spoils. It has the ability to absorb 7½ times its weight in water. Calculating the dosage requirements is simple. Measure the density of the drill spoils using a standard mud balance. Then, determine the approximate solids content using the formula: 7.5 × mud weight – 62.5 = % solids. Next, subtract the calculated solids to determine the esti- mated volume of water. The estimated volume of water is converted to total weight of water and divided by 7.5 to get the correct dosage of the formula. A solidification reagent is added to a drilling fluid pit. SOLIDIFICATION from page 19 Drilling fluid in liquid form is poured near fluid that has been solidified using a solidification reagent.