Case Histories

Dredging Silt and Debris From Missouri River

Problem to solve. In Montana two neighboring Conservation Districts in the Big Sky State forged an innovative partnership. The Missouri and Yellowstone rivers deposit silt and debris throughout the year, and, even when there is normal water flow, irrigators need to clear away debris to use their pumps. The situation is worse in years of drought or low water level. Sometimes irrigators have to trench from their pump sites to the river to access needed water. Traditionally, this has been done with draglines and backhoes (and even dynamite), and the task has become more expensive and problematic each year. Excavated debris and silt was piled on riverbanks. The mounds created could even change the river patterns to create more silt problems.\

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Equipment: Rotomite SD-110

Delegal Creek Marina, Savannah

Application. Remove silt, sand, and sediment from 74 boat slips in a private marina. Special problems: Avoid disturbing the docks, and avoid obstacles. Dredging takes place in a saltwater tidal environment. Additional purpose: Meet EPA cleanup requirements.  Operator’s station with custom ergonomic realignment of controls; Dredge sludge pump volute/case constructed of chrome carbide overlay plate; Cathodic protection (Zinc Anodes) and a rust preventative coating beneath the dredge’s epoxy paint; All fittings of stainless steel and/or aluminum to resist corrosion; Unit coated with Amerlock 400 (base coat) and Amercoat (top coat); Cutterhead shroud and drive couplers are stainless steel; auger tube, motors and tines in steel coated with Amerlock 400 and Amercoat; Sound reducing panels with a target of 87 dB or less from 200 feet distance; Set up for traverse winch were guides at the end of the platform; A belly pan below the platform/ engine compartment to prevent saltwater contact with the diesel engine.

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Equipment: Rotomite SD-110

Municipal Water Treatment in New York

The City of Troy, New York purchased a SRS Crisafulli FLUMP in 1991, and a second Crisafulli dredge, the Rotomite-SD110, in 2014. The FLUMP is a 40 HP, 4” model with wheels attached to the pontoons for easy transport around the facility. The Troy water treatment facility has two lagoons. The FLUMP is in the lagoon closest to the storage tank (See photo). The second lagoon is further down the hill, is irregularly shaped and its water level fluctuates greatly. SRS Crisafulli built a 4” J-Series artisan pump to achieve 800 GPM at 120’ TDH, which is a higher head capability than Troy’s FLUMP, and is able to maneuver around the upper pond without a cable traverse system. The application was to remove sludge from the upper lagoon and pump it to a tank for dewatering using a press. As the capacity of the plant increased, the FLUMP and press could not keep up with the sludge accumulation. The FLUMP maintains the tank’s water capacity and the Rotomite fills geotubes, which enable dried solids to be removed for disposal. The Rotomite’s variable speed pump maintains a consistent flow of slurry into the geotubes. With the two dredges, the City can keep its two lagoons cleaned and sustain the required drinking water capacity

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Equipment: Rotomite SD-110

SD-110 ships Overseas

After a year of close collaboration with the prospective customer, SRS Crisafulli built and shipped a Rotomite SD-110 shallow draft dredge to an Asian customer in 2013. Three international firms played key roles to close the deal including SRS Crisafulli’s authorized International Factory Representative. The prospective customer needed to remove sediment at its Treatment Plant. Sediment-bearing water from a regional dam and river traveled more than 30 kilometers to the Plant. The river also carried silt to the treatment Plant where sludge was collected at the bottom of sedimentation basins. To achieve acceptable, sustained settled water quality, to preserve basin capacity, and to comply with environmental regulations, the Plant needed to clean its sedimentation basins twice a year. SRS Crisafulli provided detailed product specifications and capabilities for the Rotomite SD-110 dredge, and defined what made the Rotomite SD-110 a superior dredge for the application. After SRS Crisafulli satisfactorily answering all the requests, the customer purchased the Rotomite SD-110. The Rotomite SD-110 equipment package provided a high-performing dredge pump able to move 1500 gpm at 80 ft. TDH in water. The cutterhead was 90-inches wide with a 15-inch pump opening for high sludge production. A unique hydraulic thruster enabled the dredge to be driven like a boat. Pursuant to SRS Crisafulli’s superior worldwide service, a SRS Crisafulli Factory-trained engineer traveled to Asia to support the installation and to commission the Rotomite SD-110 dredge.

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Equipment: Rotomite SD-110

SD-110 Used In Domestic Copper Mine

Application. A domestic copper mine with a tailings dam that overflowed onto adjacent forest service land had constructed a new dam to hold additional tailings. The customer needed an immediate solution to the overflow problem to avoid fines. Because the encroachment area was odd shaped with an uneven bottom and some very shallow points, we recommended Crisafulli’s aluminum hull, self-propelled, shallow draft dredge, the Rotomite SD-110.

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Equipment: Rotomite SD-110

SD-110 Used In Lion Oil Refinery

Jeff McGriff, Project Engineer, reported that the dredge would be used to “clean two 70-year old industrial storm water clay-lined lagoons that have not been cleaned for 20-30 years. One lagoon is 10 acres; the other is 2 acres.” “The depth of the lagoons (from surface to bottom, excluding sediment) is 8-9 feet. The number of feet of water between the surface and the top of the sediment is 2 feet. The material to be dredged is sandy, silty, and “sludgey” – like a thin pudding. “They plan to dredge 4-hours a day, year round, for 10 years. They have “hot spots” they intend to dredge first, and after they ‘get a feel for it’ they will develop a regular process. Mr. McGriff reports that there are big chunks of concrete in one corner and some stumps in another corner. Lion Oil’s hope is that by dredging the lagoons, they will be able to remove the concrete and stumps – thereby creating more capacity in the lagoons. Slurry will be discharged to a holding pond where the dredged material will be treated and pumped out. “Lion oil’s goal is to develop environmentally friendly and healthy practices, become compliant with EPA regulations, and increase the capacity of their lagoons” according to McGriff. Mr. McGriff said “the purchase of a dredge is a much more sound financial solution compared to alternatives such as draining the lagoons and dealing with the environmental effects as well as the expenses of hiring others to cleanup and cart the dredged material away.”

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Equipment: Rotomite SD-110