Dredging World News Blog

SRS Crisafulli Explores Dredging and Hydropower

Posted by Elizabeth Kaiser on Wed, Jan 25, 2012 @ 08:01 AM

By Elizabeth Kaiser, SRS Crisafulli Marketing Manager

Energy production and consumption worldwide is influenced by many factors.  Resource availability, economic activity, population growth and environmental regulations, for instance, all affect the types of energy production that may be available to consumers.   One of the cheapest methods of energy production is hydroelectric power.

Last spring’s press release by the U.S. Department of the Interior, Departments of Energy and Interior Announce $26.6 Million in Funding to Develop Advanced Hydropower Technologies, announced  “funding for research and development projects to advance hydropower technology, including pumped storage hydropower.”  Hydropower is a sustainable and clean power generating process.  “These funding opportunities will help unlock innovative approaches to hydropower development that emphasize sustainable, clean power generation while reducing environmental impacts.” 

What is the hydropower process?  In short, falling water is passed through a hydroelectric generator to produce electricity. Another hydropower process involves what is called “pumped-storage”. As explained by the Tennessee Valley Authority, “A pumped-storage plant uses two reservoirs, one located at a much higher elevation than the other.  During periods of low demand for electricity, such as nights and weekends, energy is stored by reversing the turbines and pumping water from the lower to the upper reservoir.”

Watch this YouTube video "Hydroelectic Power - How it Works"

 

How is dredging part of this scenario?  The most serious technical problem for hydroelectric dams is accumulation of silt which reduces the water storage capacity of the dam.   Reduced storage capacity limits both electricity generation and the availability of fresh water for downstream uses.  Periodic maintenance dredging removes silt deposits from the dam reservoir and restores water storage capacity, thereby allowing the hydroelectric dam to function more effectively. Periodic dredging can reduce potential negative impacts on fresh water availability without interrupting energy production.

 

Want to learn more about hydroelectric dam dredging?  Contact us.

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Topics: Dredges, crisafulli, dredge, dredging, srs crisafulli, dredging abrasive materials, lagoon dredges, dredging system, dredging and pumps, lagoon, rotomite 6000c, Hydraulic dredging

Dredging and Shoreline Remediation

Posted by Elizabeth Kaiser on Wed, Dec 07, 2011 @ 08:12 AM

By Elizabeth Kaiser, SRS Crisafulli Marketing Manager

Many situations can complicate a shoreline’s integrity.  These can range from flooding, hurricanes and man-made disasters and can even include aquatic harvesting and human recreation.  Making efforts to protect a shoreline from these intrusions helps protect economic and recreational interests.  Shoreline remediation is an investment in the overall economic and natural habitat of a community.

As defined by the Erosion Control Technology Council (ECTC), Sediment Control is A practice that captures soil particles on site that have been detached and moved by wind or water.   While different methods and practices are used when it comes to shoreline remediation and sediment control we will examine a specific method, dredging and shoreline remediation.

Let’s look at the Southwest Mordecai Ecosystem Restoration Project or “SWMER”.  According to the SWMER Project Scope found at mordecaimatters.org, “The SWMER Project focuses primarily on several rapidly eroding areas on the southern rim of Mordecai Island.Southwest Mordecai Ecosystem Restoration Project

SWMER complements Mordecai Land Trust’s wave barrier project with the Army Corps of Engineers which involves the planned installation of a barrier off the western coast of Mordecai north of the SWMER area.

The SWMER project required careful planning on the part of Mr. Jim Dugan, President of Pond Recovery Services of Hainesport New Jersey and contractor for the SWMER project.

Jim Dugan has owned and operated dredges for many years and has used them in conjunction with Geotubes for the purposes of shoreline remediation.  He has contracted his restoration services throughout New Jersey and surrounding waterways including the Chesapeake Bay.  President of the Mordecai Land Trust, Jeffrey Hager, wrote of Jim Dugan, regarding the SWMER project, “He (Jim Dugan) proved to be an extremely competent and conscientious field manager,…”

Jim Dugan describes the SWMER project as a material handling challenge.  “We had to move 900 tons of sand to an island in the bay.”  As described in the Mordecai Matters Newsletter, Winter 2010 issue, SWMER involves the installation of close to 600’ of huge sand-filled fabric tubes called Geotubes, slightly off the south-western edge of Mordecai Island.  “The erosion has been severe here and the hope is to stabilize this fragile part of the Island and encourage the deposition of grasses and other organic materials between the island’s edge and the two long sections of Geotube.

Jim explained that they couldn’t use the sand from the bay so they transported 900 tons of clean sand from a nearby quarry by truck.  But how do you get the sand to the island?  “You have to pump it.”  Jim said there were 2 major challenges involved.

  1. Don’t plug the pipeline with too much sand
  2. Water/tide problem

Jim needed to use the water in the bay to mix with the clean sand in order to pump the sand underneath a navigation channel, across the island, and through floating line to the Geotube feed ports.  Jim needed a flexible solution. Since he was pumping downhill under a 15 foot channel, he couldn't risk shutting down with sand in the line. He used one of his Crisafulli dredges to act as a mobile sand pump to adapt to the wind and tide level fluctuations in the bay. The dredge would be flexible enough that his operator could adjust the articulating cutterhead height, angle and distance to the feed, thus keeping the sand-water mix at an constant rate. This also allowed frequent start-stop operation to flush the line and switch Geotube feed ports, thus filling the Geotubes evenly.

sand spreader

Jim used a hopper with a belt to deliver the sand to a sand spreader.  The sand spreader distributed the sand evenly to match the 8 foot wide dredge cutterhead.  The cutterhead mixed the sand and water allowing for an optimal pump mixture.

dredge sand pump

Using the dredge as a sand pump Jim was able to pump the sandy mixture up to ½ a mile directly into each of the geotube ports spaced 20’ apart.   “(This project) needed a lot of flexibility which the dredge allowed for” Stated Jim.

Read Jim Dugan’s SWMER blog of his progress in the Mordecai Matters Winter 2010 newsletter

Watch video of the shoreline with the installed geotubes at Mordecai Island Geotubes in Action on YouTube.

If you would like to email Jim Dugan, send your email inquiry to jimdugan@comcast.net.

Watch SRS Crisafulli videos.

Topics: Dredges, crisafulli, dredge, dredging, marina dredging, srs crisafulli, dredging abrasive materials, lagoon dredges, dredging system, dredging and pumps

Proactive Dredging: A Little Now or a Lot Later

Posted by Elizabeth Kaiser on Wed, Oct 19, 2011 @ 08:10 AM

By Isaiah Helm, Applications Engineer, SRS Crisafulli

 

If public works departments had a list of fun things to do, dredging sediment out of holding ponds would not be on it.  It’s like cleaning the shower in your bathroom.  Whether you make it a frequent quick job or an occasional laborious task, time and effort must be set aside to maintain a fixture that is as critical as it is uninteresting.  This is the scenario that played out for Georgia’s Cobb County-Marietta Water Authority (CCMWA) during the summer and fall of 2010, as reported in Public Works Magazine

CCMWA had two water treatment plants and a 25 million gallon reservoir in need of upgrade to meet the EPA’s Stage 2 Disinfectant and Disinfection Byproduct Rule of 2006.  During the upgrade, one plant would be running, one shut down.  The reservoir had to be at full capacity to do this.  Unfortunately, it hadn’t been dredged since 1978 and was half full of sludge.  

 proactive dredging resized 600The reservoir was restored to its original 14-foot depth
within six months.  (Photo Credit:  Public Works Magazine)

Timing of all the different upgrade stages coupled with the EPA deadline meant the reservoir had to be cleaned out in six months.  (The dredging had originally been scheduled to take place 2013-2014.) 

In other words, the CCMWA had to make up over 30 years of maintenance in 6 months (that would be one nasty shower!).  The result: increased scale, decreased competition, and ultimately an increased cost.  The amount of dewatering equipment doubled.  Four mobile belt presses and four recessed chamber presses were used.  Fifty trucks made four 45-mile round trips per day.  Bidding on the project was limited to the few large contractors who were even capable of completing the project.  There were five bidders and all five of them listed the same two companies as their subcontractors.  Total cost to dredge the reservoir and perform maintenance on the banks and sluice gates totaled just over $4 million.

The World Dredging Mining & Construction Journal [1] contains a version of the article authored by Steve Gibbs.  It goes on to discuss some observations from the project:

One of the lessons learned by CCMWA is the need for regular dredging of the reservoir.  One benefit of regular dredging is economics – greater capacity in the reservoir reduces the amount of pumping necessary to bring water from the Chattahoochee, thus saving electrical costs.  Also, doing a smaller dredging project every five years or so will eliminate the need to do a massive project such as the one just completed.

A deeper, cleaner reservoir will allow suspended solids to settle out better, which will enhance treatment efficiency.  The reservoir will also have ample capacity while the treatment plants are in their construction phase.

“This (the reservoir dredging project) will decrease the potential for water quality problems or process issues at our treatment plants,” said Ginn (CCMWA process engineer). “It’s a very good proactive preventive maintenance step.”

There you have it.  Proactive dredging of sludge-collecting ponds really does make life easier in the end.  It also increases the options:

  • Put out a request for bids on that smaller dredging project every five years

  • Contract with a dredging company to clean out the pond every five years

  • Rent dredging and dewatering equipment directly and eliminate the middleman

  • Purchase an automated or remote dredging and dewatering system and have it permanently installed for complete self-sufficiency

At least it’s something to think about while you’re cleaning your shower tonight.

 

[1] World Dredging Mining & Construction Journal, “Proper Planning for a Perfect Project” (Volume 46, Nos. 11/12, Page 16)

 

Do you have a proactive dredging project in mind?  Fill out our dredge application form.

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Topics: Dredges, crisafulli, dredge, dredging, srs crisafulli, dredging abrasive materials, lagoon dredges, dredging system, dredging and pumps, dredging equipment rentals, rotomite sd110, lagoon, rotomite 6000c, Hydraulic dredging, rotomite 6000

Dredging for Gold in Remote Places

Posted by Elizabeth Kaiser on Wed, Aug 31, 2011 @ 09:08 AM

By Dave Stoltenberg, Dredge Rental Specialist with SRS Crisafulli

 

From Alaska to West Africa, SRS Crisafulli dredging experts are busy installing dredges and training operations personnel at producing gold mines.  Nearly all operating mines have overflow lagoons and impoundments for the collection of particulates, overflow mud, and tailings.  Typically the lagoons are lined, and are operated as part of a water treatment system to ensure all water released from the mine meets environmental regulations.  In many cases the water and particulates are acidic in nature and require specialized equipment adaptations such as stainless steel construction to ensure longevity.

Press play to view SRS Crisafulli FLUMP Dredge video

Gold mine companies find SRS Crisafulli Flumps to be an excellent choice for a variety of projects.  Small, remote controlled, extremely productive, and a high value, Flumps perform well across a wide range of applications and environments.  Project applications at gold mines are primarily for the purpose of either dredging waste sediments for dewatering and disposal or for the purpose of recovering gold from tailings or overflow sediments.  When used to dredge for disposal the sludge is sent to centrifuges or geobags, dewatered, and then disposed of.  When used to dredge for gold recovery the tailings are sent to a processing mill so the sediments can be re-processed.  In some cases tailings are recently produced, and in other cases the tailings are historical in nature yet still contain recoverable amounts of gold.

 

Gold Mine Dredging in Alaska










 

From Gold Mines in Alaska

 

 

Gold Mine Dredging in West Africa

To Gold Mines in West Africa

One characteristic shared by both Alaskan gold mines and West African gold mines is remoteness.  These operations, encompassing surface mines and underground mines, are a testament to the abilities of companies to build and sustain small cities in some of the most inaccessible locations in the world.  Alaskan locations are noted for their short summer periods and long duration cold winters while West Africa, south of the Sahara desert, is tropical in nature, with high temperatures and humidity.  Regardless of the environment, SRS Crisafulli’s attention to detail, rigorous manufacturing standards, and ability to customize solutions to the most demanding requirements results in long-lasting, dependable dredges.

Whatever your mining application, wherever in the world it might be, give one of our SRS Crisafulli dredging experts a call today to solve your problems.

 

Learn more about SRS Crisfaulli FLUMPs.

Fill out a dredge application form.

Request a free consultation.

SRS Crisafulll Dredges FAQ.

Topics: Dredges, crisafulli, dredge, dredging, dredging abrasive materials, mining

Dredging Q+A: Top 8 Questions Answered

Posted by Elizabeth Kaiser on Wed, Jul 13, 2011 @ 19:07 PM

dredging questions and answers

 

We strive to provide our customers with as much information as they need to make informed decisions about the dredging equipment they choose.

So we compiled some of the questions (and answers!) asked most frequently for your quick review.

Q: What kinds of dredges does SRS Crisafulli make?


A: SRS Crisafulli produces hydraulic dredges with horizontal auger cutterheads in two model groups - i.e., self-propelled, steerable, operator on-board diesel powered Rotomites, and remote-controlled, cabled, electrically powered, unmanned FLUMP dredges. 


Q:  What sizes do SRS Crisafulli dredges come in?

A:  The remote-controlled FLUMP comes in two sizes:  the 3-inch (standard or  severe-duty), and 4 inch severe-duty. The Rotomote SD-110 is equipped with a 4-inch pump and six-inch discharge.

The Rotomite 6000 and Rotomite 6000C models are 6x8 (a six-inch pump with an eight-inch discharge.

Q: What is a FLUMP?


A: FLUMP stands for “Floating Lagoon Pumper”.  An operator runs the FLUMP from a hand-held radio remote control, or from a shore panel connected by wire to the FLUMP.

Q: What is a Rotomite dredge? How is it different from the FLUMP?


A: The Rotomite Dredge series includes manned (“operator onboard,”) self-propelled, steerable dredges which can operate without a support vessel.  Normally, these models are diesel-hydraulic powered, although a few are offered in all-electric customized versions.


Unlike the FLUMP, the Rotomite doesn’t require a cabled traverse system to control dredge movement.  For the customer’s convenience and to increase versatility, Rotomites are designed to operate as either cabled or free-floating (not cabled,) dredges.

Q:  How deep can I dredge with a SRS Crisafulli dredging system?


A: Dredging depths are 10 feet with a standard duty FLUMP and 12 feet with a severe duty FLUMP.  The Rotomite SD-110 will dredge up to 12 feet and the Rotomite 6000 will dredge up to 20 feet.  SRS Crisafulli's newest model, the Rotomite 6000C, reaches a depth of 23 feet.  Greater depths are available as custom models.

Q:  How much material can be dredged with a SRS Crisafulli dredge?



A:  FLUMPs can dredge 25 to 80 cubic yards of settled solids per hour and Rotomites can dredge up to 150 cubic yards of settled solids per hour.

Q: How far can the dredged slurry be pumped without a booster pump?


A: Typically, Crisafulli dredges will pump slurried material up to 1,500 feet, depending on the site conditions and the slurry.

Q: What is a good application for a Crisafulli dredge? Is it right for my needs?


A: SRS Crisafulli dredges are installed in some of the world’s most demanding environments, and dredge a wide variety of materials in both industrial and municipal settings.


SRS Crisafulli dredges are frequently used in the following applications:


-Residuals from potable water treatment plants
-Biosolids from wastewater treatment plants
-Runoff ponds, basins and lagoons
-Mines (for the management of tailings)
-Power plants (for fly ash ponds and sedimentation ponds
-Refinery and petrochemical wastes
-Processing plants (Food processing; Rendering; Slaughterhouses)
-Metal processing wastes
-Chemical sludges
-Marina and canal maintenance

If you have a question that wasn’t answered in this list go to: Dredge Q+A

Learn more about our dredges here:


Unmanned, remote controlled electric dredges for industrial and municipal lagoon maintenance


Self-propelled diesel dredges can dredge about anywhere without cumbersome cabling


Self-propelled, manned, 6" diesel dredge for abrasive slurrries

Topics: Dredges, dredge, dredging, dredging abrasive materials

Dredging Abrasive Materials? Learn about SRS Crisafulli’s New Dredge

Posted by Elizabeth Kaiser on Fri, Apr 29, 2011 @ 06:04 AM

dredging abrasive materials rotomite 6000cThe Rotomite-6000-C, SRS Crisafulli’s newest self-propelled dredge, broadens the Rotomite-6000’s capabilities to include removal of highly abrasive materials. The Rotomite-6000-C also increases the customer’s return on investment (ROI) by cutting sludge management costs, increasing user productivity, and enhancing the unit’s maneuverability for the removal of toxic and non-toxic solids.

The new design offers capabilities that will benefit industrial companies, including; chemical companies, food processing plants, domestic and international construction and contracting companies, oil, mining and refining companies, petrochemical plants and refiners, and coal fired utility companies. Municipalities, County, Regional and Federal agencies, as well as lake associations, and landfill operators, will be able to use the Rotomite-6000-C in many applications. In addition, the Rotomite-6000-C helps companies comply with domestic and foreign mandates by ensuring manufacturing by-products are contained safely in order to prevent contamination of drinking water.

This versatile, self-propelled design is a horizontal auger, hydraulic dredge that can work in odd-shaped areas where a cable dredge unit cannot go. It can remove, pump and discharge dredged solids in water/solids slurries through a floating discharge pipe to disposal sites up to 5,000 feet away, or more when a booster pump is used.

The Rotomite-6000-C is 40 feet long by 9.5 feet wide, and is easily transported by truck.  Its 255-horse power motor and new propulsion system provide increased production and propulsion thrust. It will dredge most soft or abrasive materials, including alum and lime sludges, bentonite, biosolids, bottom ash, clay, coal fines, fly ash, gypsum, mine tailings and slimes, mill scale, mud, pigmentation sediments, industrial and municipal wastes, pulp and paper residuals, peat, oil API sludge, sediments silt and sand.


Capabilities include:

  • Dredging depth of 23 feet standard (up to 30 feet optional)
  • Up to 235 cubic yards of sludge solids produced hourly
  • A discharge volume of up to 3,400 gallons per minute @ 180’ TDH (water)
  • A dredging speed of up to 25 feet per minute
  • A dredging cut up to 8.5 feet wide
  • A cutterhead torque of 11,500 inch/lbs.
  • A draft of 30 inches

The self-propulsion feature provides increased maneuverability, more forward and reverse speeds and a 72-horse power hydraulic motor that powers a propeller system capable of 2,500 pounds of force. SRS Crisafulli’s exclusive Cobra cutterhead, which provides 11,000 inch-pounds of digging torque and up to 235 cubic yards of sludge solids per hour, increases productivity. The hydraulic ladder results in enhanced downward force by providing 30,000 pounds of down pressure to dig into the settled solids materials more aggressively thereby increasing cutting capacity. An improved cab design provides operator safety and convenience features, including air conditioning and heating.


rotomite 6000c cta button resized 600

Topics: dredge, dredging, srs crisafulli, dredging abrasive materials, rotomite 6000c