Dredging World News Blog

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Chad Schipman — Thu, 01 May 2025 22:58:32 GMT

Journey to Improve Water Quality in Powers Lake

lmfleming2@aol.com (Laura Fleming) — Wed, 19 Aug 2020 21:09:00 GMT

Abstract

Outbreaks of blue-green algae in Powers Lake, a 1,616-acre natural lake, created an emergent call to action in the 1990’s from the community of Powers Lake, North Dakota, USA. Ongoing community action and funding both federal and local continue to improve water quality in Powers Lake. The Powers Lake Watershed Committee received three 319 federal grants and matched federal funding with local funding. A 2001 water analysis measured Powers Lake as “hyper-eutrophic” and the watershed assessment specified the lake received an annual phosphorus load of 11,564 pounds. Significant reductions in nutrient loads entering the lake and cycling within the lake were necessary. Improving water quality at Powers Lake requires preventing nutrient pollution from entering the lake and removing sediment with an overabundance of nutrients from the lake. Farmers and ranchers within the watershed are preventing pollution from entering the lake with conservation practices. PLWC is removing sediment with an overabundance of nutrients from the lake via hydraulic dredging. Water quality continues to improve during the last 20 years.

Two Goals to Improve Water Quality

Improving water quality in a natural 1,616-acre freshwater lake is an enormous undertaking. The complexities of preventing and eliminating pollution are immense. Reaching two main goals was necessary to improve water quality at Powers Lake. Goal one was preventing pollution from entering the lake from the watershed which drains approximately 44,458 acres of primarily agricultural lands. Goal two was reducing nutrient cycling within the lake by removing sediments via dredging.

Powers Lake is located on the edge of the City of Powers Lake, North Dakota where the south end of town meets the lake. Historically, Powers Lake was of high recreational value and a natural resource to the community and known as one of North Dakota’s finest lakes for recreation and fishing and gathering.

Problems of Blue-Green Algae

In the 1980’s and 1990’s water quality deteriorated and the lake was frequently afflicted with blue-green algae blooms and fish kills. Blue-green algae, also called cyanobacteria consumes oxygen in the water. Anoxic conditions kill fish, create health hazards, and contaminate water. As a result of the blue-green blooms, the recreational value of Powers Lake plummeted, and fewer and fewer people gathered or recreated there.

Powers Lake Watershed Committee Formed

In 1998, the local community recognized the importance of Powers Lake and formed the Powers Lake Watershed Committee (PLWC) who initiated the complex project to improve water quality in Powers Lake. The committee was comprised of volunteers, educators, and representatives the City of Powers Lake and Mountrail and Burke counties including Soil Conservation District (SCD) and National Resources Conservation Service (NRCS) offices.

Watershed Assessment, Funding and Conservation Practices

Over the years, the community harnessed the talents and contributions of many individuals and organizations. They initiated a 2001 watershed assessment with Agricultural NonPoint Source (AGNPS) modeling. In 2003, they received the first of three 319 Federal grants, hired a Watershed Coordinator and began working with farmers and ranchers to implement conservation practices.

After the conservation practices significantly reduced nutrient load entering the lake, PLWC turned their attention to reducing the nutrient recycling within the lake. They pursued more funding and expertise to address the overload of nutrients within the lake.

The Powers Lake Watershed Committee received Federal 319 grants of the Clean Water Act in 2003, 2011 and 2016. The grants require a 60/40 matching from local funding. Remarkably, Powers Lake area residents, agricultural producers, and state and local folks met the challenge and matched federal funding with local funding, (cash and in-kind services) much of it through volunteer labor. The project also received a grant in 2017 from the North Dakota Outdoor Heritage Fund to assist with the cost of dredging operations.

Findings

In 1999, with assistance from the North Dakota Department of Health (NDDH) Division of Water Quality, PLWC initiated a watershed assessment and AGNPS model, which was completed in 2001. The assessment included monitoring water quality, compiling an inventory of current land use practices, and generating pollution estimates using the Agricultural NonPoint Source (AGNPS) model. AGNPS is a computer model used to predict nonpoint source pollutant loading within watersheds. The watershed assessment and AGNPS model recommended watershed restoration actions, pollutant reduction goals and outlined specific activities for accomplishing the goals and provided a method for evaluating progress.

The AGNPS modeling indicated that Powers Lake received an annual phosphorus load of 11,564 pounds with 6,339 pounds from external sources and 5,225 pounds from internal sources (nutrient cycling).The assessment report determined that for Powers Lake to meet State Water Quality Standards, it needed to achieve a 75% reduction of the nutrient load entering the lake, and a 50% reduction in the internal (nutrient cycling) nutrient load within the lake. Water sample findings through 2001 revealed the primary impairments to recreation and aquatic life in the lake were caused by excessive nutrient loadings, specifically, high levels of nutrients (especially phosphorous) and low dissolved oxygen levels.

Phosphorus is an essential element for plant life and a common ingredient of agricultural fertilizers, manure, and organic wastes. Excessive phosphorus levels accelerate eutrophication which occurred when the lake was overloaded with nutrients causing blue-green algae growth and depletion of dissolved oxygen. Powers Lake water analysis showed “hyper-eutrophic” which means poor water quality and extremely high growth of noxious surface scums of blue-green algae. As a result, the North Dakota Department of Health (NDDH) added Powers Lake to its 2002 Clean Water Act (CWA) section 303(d) list as fully supporting, but threatened, for the lake’s recreation and aquatic life designated uses.

Preventing Pollution from Entering the Lake

In 2002, the local citizens become increasingly aware of the deteriorated water quality and the loss of recreational value and a natural resource. In 2002, the community applied for a Section 319 NonPoint Source Pollution grant from the State to improve the water quality of Powers Lake. North Dakota, EPA’s Section 319 Non-Point Source (NPS) Pollution Management Program provides cost-sharing for watershed restoration projects in North Dakota including Powers Lake. The projects treat entire watersheds through the promotion of sustainable agricultural and sound land management practices.

In 2002, the Powers Lake Watershed Project (PLWC) was created with assistance from the Burke and Mountrail County NRCS, Burke and Mountrail County Soil Conservation District, US Fish and Wildlife Service, North Dakota Natural Resource Trust, and the North Dakota Game and Fish Department. Partnering with the different agencies brought more people working toward the common goal of improving water quality in the lake. They helped implement more conservation practices. Powers Lake Watershed Project developed a list of tasks designed to reduce the amount of phosphorous loading entering the lake.

They recommended implementing Best Management Practices (BMP) for Non-Point Agricultural pollution prevention.

In May 2003, the U.S. Environmental Protection Agency awarded the first grant on a 60/40 matching basis. The federal funds were matched by local funds (cash and in-kind services) from agricultural producers, PLWC, and state and local stakeholders. The Mountrail County Soil Conservation District (SCD) provided administrative services for the grant. In January 2004, a Watershed Coordinator was hired.

The Mountrail County Soil Conservation District SCD served as the administrative and fiscal agent for the project. Powers Lake Watershed Project hired staff to develop BMP contracts for agricultural producers and deliver technical assistance. Project staff worked closely with partners at the federal, state, and local level to support the project. North Dakota Department of Health (NDDH) provided oversight for project management, developed the quality assurance project plan, conducted water quality monitoring training, and helped to develop education activities.

Agriculture Producers Implement Best Management Practices

Agriculture production is the economic foundation of the Powers Lake area communities and agricultural pollution was a significant source of pollution entering Powers Lake. Much to their credit, agricultural producers changed practices and adopted Best Management Practices BMP’s for soil and water conservation to reduce the nutrient loads entering the lake. Agricultural producers, farmers and ranchers made changes that significantly reduced the amount of sediment entering Powers Lake.

Since the project began, there is a great change in the landscape. Beginning in 2003, many farmers switched to no-till or minimum till and fewer acres were fallowed across the watershed. Farmers reduced the quantity of fertilizers applied by balancing crop nutritional needs with necessary application rates.

Fortunately for the project, many ranchers in the watershed agreed to be part of the solution to reduce unwanted runoff. They made changes and adjusted their operations. They installed wells, pipelines, tanks, fencing, grass seedings, and grazing rotations. One rancher installed a waste management system to divert clean water around a feedlot and hold manure water within the feedlot until it settles out before being spread across fields as fertilizer.

Powers Lake Watershed Project also worked closely with the North Dakota Game & Fish Department, the North Dakota Natural Resources Trust, and the U.S. Fish and Wildlife Service, who provided technical and financial assistance to create or restore 9 wetlands, seed in grass, and protect the shorelines and riparian areas. In addition, local Soil Conservation District (SCD) staff worked cooperatively with local Natural Resources Conservation Service (NRCS) personnel to identify and tap all available funding assistance programs.

The data indicates the watershed conservation activities are effective at preventing nutrients from entering the lake through erosion and runoff. The Powers Lake community continues to make improvements to the watershed to reduce nutrients flowing into the lake. The changes resulted in far fewer nutrients flowing down the watershed into Powers Lake.

Watershed Conservation Activities BMP	Measurement
Res-Till 329A	19,575 acres
Nutrient Management	12,103 acres
Past/Hay planting	1,246 acres
Cover Crops	530 acres
Pipelines	32,320 linear feet
Fence	66,349 linear feet
Wells	7
Tanks	23
Grazing Systems	5,577 acres
Waste Mngt Sys	1
Tree plantings	37,040 linear feet
Well Decommissioning	1
Urban stormwater	1
Grass Easement	1,487 acres
Wetlands created	9

Water Sample Findings

The Trophic State Index (TSI) classification system is used to evaluate water quality levels based on the quantity of biological productivity occurring in the water. Carlson’s Trophic State Index (TSI) measures transparency or turbidity (using Secchi disk depth recordings), chlorophyll-a concentrations (algal biomass), and total phosphorus levels.

The water quality measurements between 2001 and 2009 indicate that TSI scores are improving. The average TSI score for chlorophyll a in 2009 was 53.24, which met the improvement criteria of a total maximum daily load (TMDL) target of 55.02, However, the phosphorus TSI scores, remained high and held steady at 85, which is rated as “hyper-eutrophic” range. The likely cause was phosphorus within the lake continually cycling from the lake’s bottom sediments.

Seeking Solutions to Remove Nutrient Loading Within Lake

In 2008, PLWC sought solutions on how to reduce the internal nutrient cycling which was feeding blue-green algae blooms. The internal nutrients are attached to the sediment and primarily composed of phosphorus. Houston Engineering Inc. was hired and completed the Powers Lake Nutrient Management Alternatives report in October 2009. They recommended removing lake sediments to reduce the internal nutrient cycling via dredging as the best remediation method.

The 2008 report from Houston Engineering Inc. also measured the depth of the lake and found the average depth to be 5.6 feet. They recommended removing 3.6 feet of sediment to increase the average depth to 9.2 feet. Dredging improves water quality in two ways. First, it removes the detrimental sources of internal nutrients and adds depth to the lake which reduces wind energy turbulence and lessens the stirring of bottom sediments. Hydraulic dredging removes bottom sediment and pumps a mixture of sediment and water, called slurry, from the bottom of the lake through a pipeline to another location.

Funding to Remove Nutrient Load in Powers Lake

The data also indicated that internal lake nutrient cycling is now the primary cause of algae production. In 2011, PLWC received a second grant of CWA section 319 funds and again matched the federal grant with local funding. This funding supported dredging to reduce internal nutrient cycling and increasing lake depths by remove bottom sediments via dredging.

City of Powers Lake Purchases SRS Crisafulli Dredge to Remove Nutrient Load

In spring 2014, PLWC considered buying a large dredge capable of quickly removing sediment, but the high purchase price and labor costs (millions of dollars) deemed it impractical. In 2015, PLWC chose a Crisafulli Rotomite 6000 dredge, priced at $300,000 as the most practical solution.

In 2014 while attending the North Dakota Rural Water Association 2014 Conference, Kenny MacDonald, Powers Lake Watershed Coordinator, met Troy Fercho, Sales Manager from SRS Crisafulli, Inc., a hydraulic dredge manufacturer located in Glendive, Montana. Troy invited Kenny and PLWC to Glendive for a spring demonstration of dredging.

In spring of 2015, members of PLWC traveled to Montana to see a demonstration and test dredges at a local lake. By July 2015, the City of Powers Lake purchased a Crisafulli Rotomite 6000. Kenny MacDonald, Powers Lake Watershed Project Coordinator has been operating the dredge for 5 seasons and discharging the sediment to a holding area near the lake. Locals reuse the sediment, which is rich soil containing nutrients, for land application, gardens and landscaping.

As of 2019, 50,900 cubic yards of sediment and 80,273 pounds of phosphorus and 32,020 pounds of nitrogen have been dredged out of the lake. The goal is to continuously remove sediment.

Measuring Water Quality Improvements

Determining the restoration progress of a eutrophic lake is not easy. Many factors affect lake ecosystems and processes. There are a variety of conditions and components driving the chemical processes of a waterbody. Climate effects like temperature, precipitation, and wind can change which processes become primary drivers. The amount of ice and duration of ice cover and timing of run-off influence nutrient levels in the lake.

The winter and summer cycles and nutrient peaks can obscure the fact that Powers Lake water quality continues to improve. During some springs and before ice-off, nutrient spikes are detected while during other springs and before ice-off, nutrient spikes are not detected. It is important to realize that those weather-related spikes are lower than the overall averages of nutrients in the years’ 2001 through 2009. As Kenny MacDonald said, “In nature, nothing ever happens in a straight line”.

Blue-green algae (cyanobacteria) is flourishing less often in Powers Lake now, because the Total Nitrogen to Total Phosphorus ratio (TN:TP) was increasing and moving closer to the threshold of a nutrient balanced lake with a ratio ranging from 10:1≤TN:TP≤ 30:1 [i]

Another indicator of water quality improvement was decreased total phosphorus levels and increased ratio of dissolved phosphorus to total phosphorus. Total phosphorus is the sum of particulate phosphorus and dissolved phosphorus which includes both organic and inorganic forms. Particulate (organic) phosphorus enters Powers Lake via attachment to soil particles through erosion, waste and decay of plants and aquatic life. Particulate phosphorus is converted to dissolved phosphorus (inorganic) phosphorus through natural chemical processes.

Conservation and Dredging Improve Water Quality

Total phosphorus levels are decreasing. Significant declines in total phosphorus levels indicate the combination of conservation activities and dredging are effective actions toward continued water quality improvement. Prior to the initial project in 2001, dissolved phosphorus comprised 45.9% of total phosphorus. During the conservation implementation phase in 2006 and 2007, dissolved phosphorus comprised 50.3% of total phosphorus. During the dredging phase of the project from 2015 to 2019, dissolved phosphorus comprised 72.6% of total phosphorus. The significant change in composition of dissolved phosphorus to total phosphorus from 50.3% during the conservation implementation phase to 72.6% during the dredging phase indicates removing in-lake nutrient sources via dredging is highly effective.

Dredging Improves Water Quality

Before the dredging began, it was anticipated that dredging would cause a temporary release of nutrients into the water. It was expected that the overall water quality where the dredge was active would be worse than the standard lake water sampling.

On the contrary, Powers Lake’s data confirms that dredging does not cause a release of nutrients into the water column. In fact, the nutrient concentrations, while mirroring the lake samples in terms of peaks and valleys, were consistently lower. The data confirms that dredging is more efficient at nutrient removal than anticipated.

Community Teamwork

For 22 years, the community harnessed the talents and contributions of many individuals and organizations worked together toward the common goal of improving water quality. This project has been assisted by farmers, ranchers, the City of Powers Lake, Mountrail Soil Conservation District(SCD), Burke SCD, NRCS in Mountrail and Burke Counties, US Fish and Wildlife Service, Burke County Extension Service, North Dakota Natural Resource Trust, Upper Dakota RC&D, North Dakota Game and Fish, Ducks Unlimited, and the many volunteers.

Reclaiming Powers Lake

Powers Lake for Water quality is improving and people are coming to Powers Lake for camping, fishing, picnicking, hiking, bird watching, swimming, boating and gathering. Powers Lake serves as a recreational area for the city of Powers Lake and Mountrail and Burke Counties.

Since 2016, Powers Lake Watershed Committee runs a fishing derby for kids. It is a fun activity where families gather and people to enjoy fishing for northern pike. An average of 100 kids participate each year, which is impressive for a community with a population of four hundred. The fishing has improved! Ask the ten-year-old boy who caught the 13-pound northern pike at the 2019 fishing derby.

Reclaiming the high recreational value and natural resource at Powers Lake is happening. Better water quality means a higher recreational value at Powers Lake. The lake is regaining its reputation as one of North Dakota’s finest lakes for recreation and fishing and gathering. The lake serves as a classroom for Powers Lake Public School, a bird and fish habitat, and an aesthetic draw to the community. As a result of the talents, contributions and collaborations of many individuals water quality has progressively improved and the community is recapturing recreational value at Powers Lake, while the community and state of North Dakota reap the benefits. A lake is a reflection on the community that lives within its watershed.

Personal interview and notes of Kenny MacDonald, Powers Lake Watershed Coordinator, Powers Lake, North Dakota

[i] Lake and Reservoir Management, Practical Applications : Proceedings of the Fourth Annual Conference and International Symposium, October 16-19, 1984, McAfee, New Jersey – North American Lake Management Society. Conference, https://play.google.com/books/reader?id=7VhGAQAAMAAJ&hl=en&pg=GBS.PA4

https://www.powerslakend.com/?SEC=632B21E8-3D73-4E70-9D25-6E4992A9FF97

https://www.epa.gov/sites/production/files/2015-10/documents/nd_powerslake.pdf

https://www.lakeaccess.org/lakedata/datainfotsi.html

https://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/null/?cid=stelprdb1042468

https://www.epa.gov/cyanohabs/learn-about-cyanobacteria-and-cyanotoxins

https://www.lakeaccess.org/lakedata/datainfotsi.html

https://www.nrcs.usda.gov/wps/portal/nrcs/detailfull/null/?cid=stelprdb1042468

https://www.epa.gov/cyanohabs/learn-about-cyanobacteria-and-cyanotoxins

https://www.sciencedirect.com/topics/earth-and-planetary-sciences/green-alga

https://www.epa.gov/nps/319-grant-program-states-and-territories

https://www.gdrc.org/oceans/river-mgmt.html

https://www.nationalgeographic.org/encyclopedia/lake/

https://en.wikipedia.org/wiki/Trophic_state_index

http://www.lake.wateratlas.usf.edu/shared/learnmore.asp?toolsection=lm_tsi

2016: A Perfect Time to Buy a Dredge

Troy Fercho — Wed, 03 Feb 2016 17:20:35 GMT

If the initial capital investment has caused you to postpone purchase of a dredge, significant tax incentives exist in 2016, which enable you to buy dredges at sharply reduced costs with little or no initial capital expense – i.e., fantastic tax programs like the Section 179 deduction, as well as low interest rate financing.

NEWS ALERT: SECTION 179 IS $500,000 FOR 2016

Jan 1, 2016 - The "Protecting Americans from Tax Hikes Act of 2015" (PATH Act) was passed by both the House and Senate and signed into law on 12/18/2015. This bill expanded the Section 179 deduction limit to $500,000. Read the summary from the Ways and Means committee here.

Section 179 Deduction: Until further notice, Section 179 is permanent at the $500,000 level. Businesses exceeding a total of $2 million of purchases in qualifying equipment have the Section 179 deduction phase-out dollar-for-dollar and completely eliminated above $2.5 million. Additionally, the Section 179 cap will be indexed to inflation in $10,000 increments in future years.

50% Bonus Depreciation will be extended through 2019. Businesses of all sizes will be able to depreciate 50 percent of the cost of equipment acquired and put in service during 2015, 2016 and 2017. Then bonus depreciation will phase down to 40 percent in 2018 and 30 percent in 2019.

IMPORTANT: Section 179 for Current 2016 Tax Year (This Year)

Section 179 can provide you with significant tax relief for this 2016 tax year, but equipment and software must be financed and in place by midnight December 31, 2016. Use this 2016 Section 179 Calculator to see how much the Section 179 tax deduction can save your company.

Source

More about the Section 179 deduction. Many businesses have heard of Section 179 but you may not understand what benefits it can provide business, large and small. Congress introduced the Section 179 deduction to motivate American companies, i.e. your business, to buy equipment and invest in themselves. The program greatly helps small businesses but can also be great for larger companies. The Section 179 deduction enables a company to purchase a piece of qualifying equipment and deduct the entire purchase price from its gross taxable income.

That’s right…THE ENTIRE PRICE of equipment purchases. There are limits to the deduction, including a cap of $500,000 and total equipment purchases of $2,000,000, and you must put the equipment into service by December 31 of the tax year you plan to gain the benefits of Section 179. The equipment must also be used 50% of the time for Business.

In addition to the Section 179 standard deductions mentioned above, there is Bonus Depreciation of 50%; meaning once you have reached the $2,000,000 cap you can depreciate an additional 50% of the balance for the 2016 tax year.

Equipment Purchase Price	$635,000
First year write off (max for 2015)	$500,000
50% Bonus First Year Depreciation	$67,500
Normal First Year Depreciation (20%)	$13,500
First Year Tax Deduction ($500,000 + $67,500 + $13,500)	$581,000
Cash Savings ($581,000 x 35% tax bracket)	$203,350
Equipment Cost After Tax	$431,650
Source

The foregoing example it makes it easy to see how it’s a perfect time to buy that piece of equipment you have been waiting for. Who wouldn’t want a 32% discount?

Other Section 179 benefits: It not only works on purchases but also if you decide to finance or even lease your equipment. For a list of qualifying equipment please refer to the IRS page.

A few more things to consider. Your equipment purchase must be used at least 50% for business. There is also a business profit limitation, which means you may not use a Section 179 deduction to deduct more than your net taxable business income for the year. But If you purchase equipment for more than your taxable income you are permitted to deduct the amount up to your taxable income, and you may also deduct the balance and in subsequent tax years. Also, if you show a net loss for the year, you may not take a Section 179 deduction for that year.

If you have any questions about the Section 179 deduction, please review your purchase plans for 2016 with your tax adviser. SRS Crisafulli has inventory of our full line of dredges to meet your needs. Below, see what a purchase of our Rotomite SD-110 dredge might look like – i.e., again a 35% discount using Section 179. WOW!

Equipment Purchase Price	$324,000
First year write off (max for 2015)	$324,000
First Year Tax Deduction	$324,000
Cash Savings ($324,000 x 35% tax bracket)	$113,400
Equipment Cost After Tax	$210,600
Source

Contact one of our sales professionals to discuss your dredge equipment needs. We would love to create an equipment package customized for you and enable you to take full advantage of the great Section 179 tax benefit in 2016.
ACT NOW!

Plug and Play Dredging: how to Move Sediment to the Drying Bed

isaiahh@crisafulli.com (Isaiah Helm) — Mon, 08 Jun 2015 15:10:05 GMT

Got a minute? Watch a one minute video of the plug and play SD-110 Rotomite dredge in the Philippines.

"Plug and Play" is a catchphrase of USB computer gadgets, representing equipment that can be connected to a system and used immediately. No system configurations; no drivers; no troubleshooting compatibility. In the modern world of plug and play, rapid system deployment is more than a feature - it's an expectation.

The dredging world is subject to these same expectations. For example, in the Philippines, a city water plant had settling ponds filled to the brim with sediment. The low capacity severely restricted their ability to process water. The solution was a “plug and play” dredge: the Rotomite SD110 from SRS Crisafulli, Glendive, MT.

A self propelled diesel dredge excels in rapid deployment. No need to configure for foreign electric standards. No need to install a cable traverse system or run three phase power lines. No need to rotate or side shift a floating dredge that’s encased in mud on both sides and can only excavate material in a straight line in front of it.

Image 1: Water plant settling pond full of sediment, Maynilad Water Services, Manilla.

The Rotomite SD110 can float in 17 inches of water and turn as it dredges. A spinning propeller in shallow water stirs up a lot of mud. Muddy water is a cancer to water cooled outboards but has little effect on the SD110’s sealed hydraulic thruster. Paddle wheels seem like a natural choice in shallow situations, but their bulk outweighs their effectiveness. Turning a long dredge body with paddles is cumbersome, and in deep, soft mud any added traction will be lost in added drag. The SD110 gets 500lb of thrust from a 12 inch prop assembly, which can quickly apply full power in forward or reverse in a 180 degree arc. The result is excellent maneuverability, even when pushing against mud and dragging along a floating pipeline.

All these features were critical at this Philippine site. The sludge was destined for drying beds south of the pond, so the logical approach was to start dredging on the south side. Production is best with a shorter pipeline. However, the only spot with even a token water depth was by the pond’s north end intake. The dredge would be inserted with mud on all sides and any movement would have to be in a canal of its own making.

Image 2: Rotomite SD110 floats in the pool it has excavated, first day Dredging

Floating discharge line was connected to the SD110 before the crane picked it up, and dredging began the moment it set down. Due to the water shortage, the discharge was dumped back into a different section of the pond. That allowed solids to settle out and water to run back and fill up the hole being excavated. Within a few hours enough material was removed to let the dredge turn in any direction and dock up against the shore. One day later, the SD110 had channeled its way to the south shore and had begun filling the drying beds.

Mine Restores Basin Capacity with Hydraulic Dredge

isaiahh@crisafulli.com (Isaiah Helm) — Tue, 18 Nov 2014 19:35:00 GMT

SRS Crisafulli introduces the Rotomite model 6000-CD Dredge

SRS Crisafulli designed and built the self-propelled, steerable, diesel powered all-purpose dredge for both abrasive and soft slurries with a cast alloy pump, and 8” discharge, in the fall of 2013. The dredge was tested at Fisher Sand and Gravel’s pond on Circle Highway northwest of the Company’s Glendive, Montana manufacturing plant, just before winter set in.

Photos: R6CD dredge testing at Fisher Sand and Gravel, Glendive MT, 2013

2014 Job Site

During the winter, the SRS Crisafulli Dredge Sales and Rental Department worked with a copper mine in the American Southwest on a Dredge Rental contract. The mine needed to restore their basin capacity without stopping mine processes, which is the perfect application for hydraulic dredging.

Dredge Application:

Problem: The customer has a plastic-lined tailings dam that collects outflow from various processing facilities. The mixture is generally acidic, with lye added to balance ph levels. A floating pump transfers water and material from this small catch basin into a very large permanent tailings impoundment. The limited ability of the floating pump to pull in slurry led to a build-up of solids, which reduced the pond’s holding capacity.

The customer wanted to restore this capacity to original levels without stopping any mine processes or damaging the liner.

Solution: The new SRS Crisafulli Rotomite model 6000CD was selected for its ability to handle abrasive tailings materials. The Rotomite 6000CD also proved to be well suited for pumping through 500 ft. of 8 in floating discharge pipe, 1500 ft. of 10 inch fused pipe, and over an 80 ft. berm at 1300-1500 gpm. No booster pump was required, reducing cost and complexity of the system. The cutterhead was outfitted with a liner protection cage, preventing its horizontal auger from damaging the liner as it pushed slurry into the pump. This cage restricted the auger from digging into settled solids, so SRS Crisafulli’s unique cutterhead articulation became indispensible as the primary method of breaking up material.

The hydraulic thruster on the back of the Rotomite 6000CD was also a critical component. Both the perimeter and floor of the basin are irregularly shaped, and it is surrounded by a fence, making cable positioning difficult and cumbersome. The thruster’s 180 degree range of motion and hydraulically variable depth allowed quick and easy positioning of the dredge during operation and docking.

The project began with an estimated 76,000 cubic yards of material to be removed. A satisfactory quantity of tailings was removed to restore the impoundment’s capacity.

Thanks to the SRS Crisafulli dredge rental program, the copper mine’s project was completed in less than six months.

The inaugural season of the R6CD was a great success.

Please call the offices to schedule a rental for 2015, or inquire about an equipment purchase.

The world's largest stormwater alum treatment facility - in Florida

ericl@crisafulli.com (Eric Lillberg) — Fri, 09 Aug 2013 18:26:00 GMT

Stormwater in the Florida canal system is slow moving. The green, murky water in the lakes fed by the Apopka-Beauclair canal is caused by an overabundance of algae-feeding compounds, mainly phosphorus, resulting in chronic algal blooms. The Nutrient Reduction Facility (NuRF) project designed a system to inject aluminum sulfate (alum) into the nutrient-laden water in direct proportion to the stormwater volume.

Environmental Research and Design, Inc. (ERD) was founded in 1986 by Dr. Harvey H. Harper, P.E. as a water quality research and engineering firm. Work efforts at ERD are devoted primarily to the areas of surface water and groundwater management, stormwater treatment, lake restoration and sediment/water interaction. This specialization has allowed ERD to develop complete field, laboratory, computer and engineering related resources in these areas.

ERD has designed, permitted, and administered construction on more than 50 alum stormwater treatment systems, reflecting more than 90% of the existing systems world-wide. During 2008, construction was completed on the Lake County Nutrient Reduction Facility (NuRF) which has a treatment capacity of 300 cfs and is the largest system in existence. The system includes two floc storage ponds, a dedicated dredging system, floc dewatering system including centrifuge, and a floc storage area.

SRS Crisafulli participated with ERD and Dr. Harvey on the Lake County Nutrient Reduction Facility build. In fact, SRS Crisafulli shipped two FLUMP remote-controlled dredge systems and an electric rail traverse system to this job in the summer of 2008.

SRS Crisafulli's Senior Application Engineer, Eric Lillberg at the Ribbon Cutting Ceremony, Lake County Water Authority, Florida

Dr. Harvey's research, which is very measured, indicates that "alum treatment of stormwater consistently provides removal efficiencies of 85-95% for total phosphorus, >95% for total suspended solids (TSS), 35-70% for total nitrogen, 60-90% for metals, and 90-99% for total fecal coliform bacteria."

The Nutrient Reduction Facility (also known as "NuRF") is a $7.272 million cooperative water quality improvement effort by the Lake County Water Authority, the St. Johns River Water Management District and the Florida Department of Environmental Protection. The project uses off-line alum injection to remove pollutants flowing out of Lake Apopka into the rest of the Harris Chain of Lakes. Lake Apopka was historically one of the most polluted lakes in Florida, but restoration efforts are underway and there have been some signs of improvement. Still, discharge from the lake is the single largest source of controllable pollution in Lake County, Florida.

Gibbs & Register, Inc., a general contractor licensed in Florida was the general contractor on the project. SRS Crisafulli worked with Equipment Plus, it's Florida Representative, on this pilot project. Equipment Plus has been providing leading edge solutions to Florida's Water and Wastewater Industries since 1987, and collaborating with SRS Crisafulli from the beginning.

Larry Hickey at Equipment Plus reminds us that nutrient reduction is a key focus driven by the EPA and now adopted in State standards. Florida has recently implemented a set of numeric nutrient standards for lakes, springs, and streams. Those are available at the Florida FDEP website.

We can think of a few other regions which might consider this approach to manage the excess nutrient load in their lakes and streams.

To read more about our business partners on this innovative nutrient removal process, here are the links:

Environmental Research and Design, Inc. (ERD)

Gibbs & Register, Inc.,

Equipment Plus

Lagoon Maintenance Dredging every Decade

lmfleming2@aol.com (Laura Fleming) — Thu, 21 Mar 2013 17:58:00 GMT

SRS Crisafulli has discovered the Rural Water Association. This winter, Troy Fercho, Frank Robinson, Tristan Hoff and I attended shows in North Dakota, Montana, Minnesota, and Idaho. At these Rural Water Association Trade Shows, we promoted SRS Crisafulli's dredge equipment and rental services to assist communities in managing the long term, low cost resource of their wastewater lagoon systems.

When lagoon operators use proven, successful, operating and maintenance procedures, Wastewater Lagoon Plants can get in compliance, and can stay in compliance. Many lagoons have been in service for 30, 40, or 50 years. Lagoons should be desludged every 8 to 10 years for optimum performance.

One of our dredge systems, the remote controlled Flump Dredge System, pictured here, is an electric, unmanned system that is available for sale or can be rented directly by a facility or by a contractor. All of our dredge systems are made in the USA – in Montana to be exact. We provide installation and operator training for dredge sales anywhere in the world, and for rentals anywhere in the USA and Canada.

What have we learned at the Rural Water Shows? One of the high notes of the Great Falls conference was meeting Steve Harris, an independent consultant from Arizona, who has provided lagoon optimization and troubleshooting services for over a decade. Steve gave several presentations on lagoon troubleshooting at the Montana Rural Water Association convention in Great Falls.

How to Upset a Wastewater Treatment Plant

Steve Harris put a little bug in my ear about the impact of methamphetamine laboratories on wastewater treatment lagoons. Quick investigation produced a similar article in the December, 2012 issue of Treatment Plant Operator, by wastewater treatment plant Laboratory Detective, Ron Tygar, entitled, "Knowing What’s Coming." Ron writes: “Industries are not the only sources of discharges that can upset treatment plants. Residential abusers can have big impacts, too.” In his article, Ron, gave two specific examples of residential sewage abusers - deep fat turkey fryers, and methamphetamine labs.

In the first case, residents sometimes face the dilemma of what to do with 7 to 8 gallons of used cooking oil once the Thanksgiving holiday has passed. Some ingenious homeowners have discovered that the 3-inch PVC clean-out cap sticking up in the yard is conveniently connected to the local sewer system.

In the second case, the high levels of waste ammonia discharged into the sewer system along with other hazardous substances create a high-strength, or even toxic waste to the fragile micro-organisms.

Troubleshooting your Lagoon

Steve is the author of Wastewater Lagoon Troubleshooting - An Operators Guide to Solving Problems and Optimizing Wastewater Lagoon Systems. Steve's textbook charts eight general problems in lagoon management:

(1) low dissolved oxygen, (2) toxicity, (3) odors, (4) low temperature, (5) high coliform, (6) high BOD (biological oxygen demand), (7) TSS Control (total suspended solids), and my favorite, (8) “Short Circuiting” which refers to hydraulic inefficiencies that allow wastewater to exit a lagoon over a time shorter than necessary to completely stabilize it.

In terms of the potential value to lagoon operators of a dredging resource, removing sludge scores a 7 out of 8. Steve offers at least five strategies for each of the eight major issues on the way to optimum lagoon performance and compliance.

There are many fine points in managing wastewater systems. Our interest as a supplier of "sludge removal systems" is to support the longevity and efficiency of lagoons as operating systems.

As Steve Harris writes in the preface to his textbook, “The knowledge concerning diagnosing and solving operational problems in wastewater stabilization ponds has been greatly expanded over the last twenty years. Many papers have been published in scientific journals and several excellent books have been written on the subject of wastewater lagoon systems. Years of consulting with lagoon operators across the US, Canada, Mexico and Central and South America has shown me that little of this valuable information ever reaches lagoon operators.”

Another resource that addresses that same knowledge gap is the Maine Lagoon Systems website, which has a mission is to promote clean water resources through the enhanced communication of wastewater lagoon system operators in the state of Maine and beyond. This website provides an online presence in which operators of lagoon systems can network with each other on various issues of wastewater treatment relative to today's demand of a clean water environment.

A technical note from the Maine Lagoon Systems offers the following:

It has been reported that as many as 60 percent of the BOD5 (The amount of dissolved oxygen consumed in five days by bacteria that perform biological degradation of organic matter) violations nationally may have been caused by nitrification in the BOD5 test rather than by improper design or operation (Hall and Foxen 1983). Consequently, millions of dollars may have been spent needlessly on new treatment facilities.

To decide if you too want to meet Steve Harris, a 2009 lecture is available on YouTube.

H&S Environmental is committed to helping you get better performance from the wastewater lagoons you're already using. Their goal is to provide wastewater lagoon operators with practical, easy to use and cost effective tools to solve their toughest wastewater lagoon challenges. H&S Environmental is committed to the belief that wastewater lagoons are capable of producing high quality effluents...effluents that will consistently meet tougher new permit limits. Some of the chief problems with wastewater lagoons are operational, but many lagoon problems are the result of design deficiencies that can be fixed.

To learn more about Lagoon Dredging or to inquire about dredge rentals or purchasing options...

Steve Harris, H & S Environmental

Maine Lagoon Systems

Rural Water Association

Treatment Plant Operator

The Experts’ Views of Horizontal Hydraulic Auger Dredging

SRS Crisafulli — Thu, 14 Feb 2013 21:48:00 GMT

Four Major Benefits of Horizontal Hydraulic Auger Dredges

I attended the Texas A & M University dredging short course in January 2013. Despite the mountain of excellent information I gleaned from the course, I was disappointed that my dredging field wasn’t featured. Horizontal hydraulic auger dredging has been around for nearly 50 years, but remains the unknown stepchild of the dredging world. That may be changing as environmental dredging becomes more prominent. Horizontal hydraulic auger dredges are ideal for environmental projects for several reasons.

First, horizontal hydraulic auger dredges are small. I know everybody wants bigger, but small has advantages. One advantage is cost. Small horizontal hydraulic auger dredges are priced for as little as $200,000 for a new unit. Even the largest horizontal hydraulic auger dredges don’t break the $1,000,000 mark. Another advantage is transportability. Most horizontal hydraulic auger dredges can be carried on standard step-deck trailers. These units come fully assembled and are ready to begin dredging as soon as you put them in the water. A final advantage of small size is dredge productivity. Current dewatering and decontamination methods handle about 1000 gallons per minute with larger units handling about 2500 gallons per minute, numbers that match closely the productivity of horizontal hydraulic auger dredge pumps.

A second benefit is ease of use. Alternative cutter-suction dredges are complicated. To use a cutter-suction dredge the operator must worry about step angle, advance, moving into the cut, cutting the bank, Net Positive Suction Head Required (NPSHR) and vacuum, winch placement, cut angle and a host of other problems. Horizontal hydraulic auger dredges move forward; that’s it. Just point the dredge where you want to cut, lower the cutterhead, and move forward. This simple system can be taught to any employee/operator in less than half a day. The pump is mounted on a “ladder” eliminating worry about NPSHR. Dredge cuts are in broad lanes, which are easy to track even without a complicated sonar assembly.

A third benefit, and perhaps the most important, is turbidity. Cutter-suction dredges kick a cloud of dredged material into the water and then the operator hopes he can suck all that undesirable material into the mouth of the dredge pump. Unfortunately, cutter-suction dredges are never able to suck all that material up, and leave as much as much as 20% of all disturbed solids. In environmental cleanup projects that’s 20% of polluted material left in suspension, enough to get most job sites shut down. By contrast, horizontal hydraulic auger dredges push the dredged material into a shroud that directs the material into the pump’s suction mouth. The shrouding of material enables horizontal hydraulic auger dredges to suck up as much as 99% of dredged material, a highly desirable result.

The final reason to consider a horizontal hydraulic auger dredge for your project is closely related to the second reason. The cable traverse system of horizontal hydraulic auger dredges makes them easy to control remotely. Unmanned horizontal hydraulic auger dredges provide safety in jobs where you don’t want your people in the water. If the material is bad enough that it requires an environmental cleanup, you probably don’t want your people in the water. I know that when I’m operating a dredge I prefer to be sitting in a lawn chair sipping a cool drink, rather than on a dredge surrounded by 5 million gallons of toxic material.

This isn’t a comprehensive list of the reasons you might use a horizontal hydraulic auger dredge for environmental cleanup, but it covers many of the high points. No dredge is perfect. There are benefits and uses for every dredge type, but horizontal hydraulic auger dredges are ideally designed to handle most environmental dredging projects.

Dredging the Hudson River

elizabethk@crisafulli.com (Elizabeth Kaiser) — Wed, 30 May 2012 22:34:00 GMT

By Laura Fleming, SRS Crisafulli President and CFO

SRS Crisafulli follows the activities of our larger corporate cousins tackling tough environmental remediation dredging projects. One of the toughest is the Hudson River EPA PCB GE cleanup.

Video Source: Hudson Dredging Video; The Hudson River Dredging Project

Dredging has resumed in the Upper Hudson River for the 2012 season - Phase II Year 2. Massachusetts based Cashman Dredging & Marine Contracting Co., LLC is performing the dredging. The crews are working 24/6 on this seasonal, multi-year project.

Photo Source: Cashmandredging.com; "Hudson River PCB Remediation Phase II 2012"

350,000 cubic yards, or 400,000 tons, of sediment will be dredged from the Hudson River this year. The sediment will be unloaded, processed, dewatered, and disposed of.

Cheers to Cashman Dredging & Marine Contracting as they move forward on this difficult river cleanup.

The Hudson River Dredging Project - read more

GE has published a series of technical papers for the Hudson River Dredging Project. As this is a PCB project, evaluation of resuspension is critical. A more abstract issue is a future looking model of species weighted fish fillet average PCB concentration for 2020 and 2046.

You may also read about the Hudson River PCBs Superfund Site on the EPA website. This project was debated and then planned for many years. It is good news to see the execution phase vigorously continued.

Suggested Tips: Dredge Maintenance Schedule

elizabethk@crisafulli.com (Elizabeth Kaiser) — Wed, 16 May 2012 14:09:00 GMT

Whether you have just installed your new dredge or you have been dredging for a while, you should follow a lubrication and maintenance schedule in order to ensure a long and useful life for your dredge. SRS Crisafulli includes a suggested maintenance schedule in our dredge Operations and Maintenance (O&M) manuals.

The following suggested maintenance schedule is included in all SRS Crisafulli dredge Operations and Maintenance (O&M) manuals.

LUBRICATION & MAINTENANCE SCHEDULE (ROTOMITE):

DAILY: