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Water Distribution

New Water Treatment Plant

October 24, 2022

New Water Treatment Plant

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Vision Becomes Reality

Iowa Lakes Regional Water's Osgood Water Treatment Plant

Project Owner:
Iowa Lakes Regional Water

Key Experience:

  • RD Water and Waste Disposal Loan and Grant Program Funding
  • Piloted technology to prove concept

Key Features:

  • Direct treatment reverse osmosis water treatment plant
  • 750,000 gpd capacity, expandable to 2.25 MGD
  • Utilizes shallow alluvial wells located approximately 2.5 miles away from the plant
  • Membraned system provides a modular style construction that allows for easy expansion

Iowa Lakes Regional Water (ILRW) provides water service to small communities and nearly 5,000 rural residents in northwest Iowa. The ILRW system encompasses over 200 square miles of service area in all or parts of Dickinson, Emmet, Clay, Palo Alto, Buena Vista, Sac and Cherokee Counties in Iowa and Jackson County in Minnesota. Water demands within the ILRW system are diverse, from high residential and tourism demands in the Lake Okoboji and Big Spirit Lake areas in the northern part of the system, to rural residential and large agricultural demands in the remainder of the system.

The Lakes area of the ILRW system has experienced significant growth as it has become a popular tourism location for residents of the upper Midwest. As ILRW developed the Lakes Area, they initially purchased water from a municipal system that treated surface water from Lake Okoboji. This source was an economical option to get the new distribution system started, but recent changes in surface water treatment has led to rising treatment costs and challenges with increasing disinfection byproduct concentrations. ILRW had the goal to provide this area and other rural customers with a higher quality and more economical water source than what they received from their bulk sources. A new treatment plant, the "Osgood" water treatment plant, fulfilled that goal.

The development of the Osgood water source has been a goal of ILRW for decades. As ILRW developed the eastern side of its system, ILRW and DGR Engineering (DGR) worked together to design and install transmission capacity capable of incorporating the Osgood water source, knowing that the new WTP would be needed in the future. The three goals of the project were as follows: to gain independence from purchased water sources, to provide high quality water to existing customers, and to accommodate system growth.

The plant is located along the Des Moines River between Graettinger and Emmetsburg, Iowa. The well field is in a shallow alluvial aquifer approximately 40 feet deep located 2.5 miles east of the water treatment plant and on the eastern side of the Des Moines River. The water treatment plant is located on the western side of the river at a much higher elevation and out of the flood plain of the river. Osgood has a capacity of 750,000 gallons per day and is easily expandable to 2.25 MGD.

The project was developed using the United States Department of Agriculture Rural Development’s (RD) Water and Waste Disposal Loan and Grant Program, which has been the primary funding source for many ILRW projects. ILRW was able to obtain a loan and grant package from RD that enabled the project to be affordable to existing ILRW customers without having to raise rates.

All of ILRW's existing sources provided softened water, so it was prudent that any process considered incorporate softening. Hardness removal can be achieved through precipitation within conventional processes (lime softening), ion exchange, or non-conventional processes such as electrodialysis and membranes.

During the preliminary engineering report phase, ILRW and DGR evaluated three alternatives to achieve the treated water quality goals:
• Lime softening
• Nanofiltration/reverse osmosis (RO) with pretreatment
• Nanofiltration/reverse osmosis direct treatment

Many alternatives were considered but a direct treatment reverse osmosis water treatment plant was selected due to the lowest initial capital investment and ease of operation. The membraned system also provides a modular style construction that allows for easy expansion as system demands increase.

Reverse osmosis treatment without pretreatment for iron and manganese removal may not always be successful, so the technology was piloted to prove the concept would work. The pilot demonstrated that the water source was a great fit for direct treatment by reverse osmosis. In addition to iron, manganese, and hardness removal, softening membranes have an added benefit of removing other contaminants, such as nitrate, which is always a concern with shallow alluvial aquifers in agricultural settings. Nitrate levels are currently below the EPA's MCL, but test drilling showed elevated levels near the well field.

Not all membrane equipment suppliers are advocates of direct treatment, and so to ensure a successful project, ILRW decided to procure the membrane equipment prior to final design. The equipment procurement process allowed ILRW to make a selection of the equipment manufacturer based on qualifications, construction cost and operating costs, and allowed the equipment manufacturer to join the design team for final design.

The project was bid at the beginning of the pandemic (April 23, 2020) with very competitive bids. Six bids were received on the project with all bids being within 5.5-percent of the low bidder. The project was awarded to John T. Jones Construction Company on June 26, 2020, and substantial completion on the project was granted on January 25, 2022.

While direct treatment with softening membranes is not uncommon in and of itself, this project was unique in that it utilized shallow alluvial wells located approximately 2.5 miles away from the treatment plant. Due to the long raw water pipeline, ILRW and DGR determined that best practices would be to include a means to pig (clean the inner walls of pipes) the raw water pipeline in the final layout.

Based on the pilot water quality results and operating pressures, a hybrid skid was designed which utilized two different styles of membranes in each stage to target different contaminants. The RO skid was also designed for two half-sized trains on one frame to minimize the footprint and reduce overall capital costs. The half-sized trains allowed the plant to operate for a longer duration during low demand and minimize the amount of water wasted during the raw water pipeline flush period between startups/shutdowns. Thirdly, two treatment trains on one skid allowed for redundancy of the treatment equipment.

Treated water quality from the new Osgood WTP is summarized in the following table:

As indicated in the table above, the Osgood WTP produces high quality water for the customers of ILRW, a quality unmatched by most water systems. The water quality produced by Osgood is equivalent to the water quality produced by ILRW’s other water treatment plant, providing customers with consistent water quality regardless of water source. The consistent water quality has significantly reduced taste and odor complaints because the use of other bulk water sources has been significantly reduced. Osgood has reduced ILRW’s dependency on outside water sources, reduced operational costs, and set ILRW up to provide water for future demand growth.

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Pump Station & Storage Reservoirs

July 19, 2021

Pump Station & Storage Reservoirs

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Water Source Resiliency
For Southwest Minnesota

Lincoln-Pipestone Rural Water System

Project Owner:
Lincoln-Pipestone Rural Water System

Key Experience:

  • Designed pump station for versatility with three initial discharge headers, one future discharge header, and two fill directions for the reservoirs
  • Reconfigured distribution system including controls of existing facilities to accommodate replacement water source

Key Features:

  • 21-mile, 14-inch diameter PVC pipeline
  • Two 400,000-gallon glass-fused-to-steel ground storage reservoirs
  • 1,620 gpm pump station
  • New connection to serve the City of Edgerton

Lincoln-Pipestone Rural Water System (LPRW) serves approximately 4,500 customers, including 32 towns as bulk customers, in ten southwest Minnesota counties. Traditionally, LPRW treated water from their Holland water source using a reverse osmosis (RO) treatment process to remove nitrate in parallel with pressure filters for iron and manganese removal. When the Minnesota Pollution Control Agency notified LPRW that their RO discharge permit would be discontinued, LPRW needed to secure a replacement treatment process or replacement water source.

To fill this need, LPRW and DGR Engineering (DGR) undertook the Edgerton Pump Station, Reservoirs, and Pipeline project. The improvements allowed LPRW to replace the source capacity lost at the Holland water source with their water allocation from Lewis & Clark Regional Water System. LPRW is one of the founding members of Lewis & Clark, and LPRW’s ability to adapt to an alternative water source is a credit to the organization’s foresight and resiliency.

DGR tackled the unique challenge of fundamentally changing operations for the south half of LPRW’s system. LPRW’s original Edgerton Pump Station received water from the Holland WTP and pumped it east to serve customers and to fill the Chandler Elevated Tank. A new Edgerton Pump Station was designed to handle all of the same demands as the original Edgerton Pump Station and to pump water back toward the Holland WTP to serve territory previously upstream of the original Edgerton Pump Station.

Lewis & Clark has a metering facility for Rock County Rural Water District at the City of Magnolia, MN and agreed to sell water to LPRW from that facility. DGR designed 21 miles of 14-inch diameter PVC pipeline to deliver water from Lewis & Clark’s meter station to the new Edgerton Pump Station. The pipeline design includes provisions for a future booster station, which will be needed if LPRW purchases more water from Lewis & Clark in the future.

During preliminary planning, the City of Edgerton requested a bulk water service connection from LPRW. The pipeline was intentionally routed to pass near the city’s well building for a service connection to the city. A related project for a meter/pump station for the city service is currently under construction.

The pipeline delivers water to two 400,000-gallon, glass-fused-to-steel ground storage reservoirs at the Edgerton Pump Station site. The reservoirs provide flow equalization and improve pump station operability and reliability. Two reservoirs allow for redundancy in case one reservoir is out of service for maintenance or repairs.
The new Edgerton pump station consists of seven vertical multistage pumps which serve three separate discharge headers, and the station includes provisions for increasing the capacity in the future. Special consideration was given to the pipe and valve configuration so pumps can be used for multiple headers for redundancy. The station also is able to fill the reservoirs from the Holland WTP in case of source interruption from Lewis & Clark.

DGR worked closely with LPRW to incorporate preferences for station layout, pump size selection, and station capability options. DGR designed the control system and worked with multiple SCADA providers to coordinate control integration for the new facility and for communications with other water systems.

Total construction cost of the pump station, reservoirs, and pipeline project was $5.1 million, which was financed using a combination of USDA Rural Development loan and Minnesota Public Facilities Authority Point Source Implementation Grant (PSIG) funding. DGR worked with LPRW to secure funding and administer state prevailing wage requirements dictated by the PSIG funding. The new Edgerton Pump Station will allow LPRW to meet current and future water demands and provide their customers with reliable, high quality water.

Click here to read this story in the newsletter.

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Site Development

April 27, 2021

Site Development

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site layout and grading key
to project's success

Sunnybrook Village, Sioux City, IA

Project Owner:
AP Sioux City, Dallas, TX

Key Experience:

  • Building Layout Coordination
  • Site Access
  • Site Utilities
  • Significant Site Grading

Key Features:

  • 42-acre retail development
  • Two primary retail buildings
  • Four outlots
  • Free-standing buildings

The area’s growing population had generated demand for additional shopping options in Sioux City, Iowa. DGR Engineering (DGR) worked with the developer and initial tenants to develop a 42-acre retail subdivision on the south end of Sunnybrook Drive.

Prior to 2000, the area consisted of farm ground and an open ditch. The Sunnybrook Plaza project included installation of a 3,000 ft. box culvert through the site and grading to fill in the ditch. Also included in the project were utilities, a lift station, site grading and paving of Sunnybrook Drive to support the two main anchors, Target and Lowe’s, along with six other lots for future tenants.

Later, DGR projects included additional grading and paving of Sergeant Road, the extension of Sunnybrook Drive to Christy Road, and preliminary grading for the future site of Sunnybrook Village.

DGR worked with the developer to put together a preliminary layout for the site. However, when Fleet Farm expressed interest in putting a 200,000+ square foot building on the site, a significant revision was needed to fit the larger building footprint and required parking on the site.

The use of AutoCAD Civil3D® allowed DGR to redesign the site plans by moving the building pad back toward the hill and steepening the slope behind the building. Coordination between multiple entities to create a mutually satisfying layout of buildings, parking area, utilities and street access was a main element of the planning process.

The current construction will provide 274,000 square feet of retail space for Fleet Farm and Hobby Lobby, a free-standing Fleet Farm car wash/gas station/convenience store and room for an additional 44,900 square feet of retail space. 1,208 parking stalls will be provided in the initial phase of construction. Future development on the site will include four outlots for future stores or restaurants, as well as space for one additional free-standing building.

A challenge this job presented was the existing flood plain designation along Sunnybrook Drive. Documenting DGR’s previous design work on grading and storm drainage work enabled DGR to work with FEMA to obtain a Letter of Map Revision (LOMR). This removed the flood plain designation, allowing work to move forward on the project.

Site utilities include installation of water main and sanitary sewer to serve each building, as well as storm sewer to collect site runoff. The runoff will be delivered to an existing 72” storm sewer along the front of the site. It will then be carried into the existing storm water detention area on the south side of Christy Road.

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Force Main Replacement

April 15, 2021

The City of Brandon’s existing sanitary sewer force main had separated under Split Rock Creek along the north side of Aspen Boulevard. The City put a temporary force main in place to maintain service to the residents east of Split Rock Creek, which ran across the Aspen Boulevard bridge over the creek.

To avoid the line freezing, and prevent the potential issue of the exposed temporary force main being damaged by traffic, the City needed a repair project designed and constructed in a short time frame. DGR Engineering (DGR) was contracted to design a new force main that would be installed under Split Rock Creek, and at the same time, a new 16” water main was designed to replace the existing water line to facilitate future development needs.

The City had also been experiencing severe erosion in the ditch east of Split Rock Creek and wanted to address that issue along with the project. DGR engineers worked with several suppliers to find an appropriate erosion control solution that would withstand the runoff flows and grades in the ditch up to 15%. Flexamat was chosen as the best product to meet the needs of the City.

Water Main Replacement

October 5, 2018

This project consisted of water main replacement on St. Paul Avenue from Benson Road to 39th Street North in Sioux Falls, South Dakota.  Work included water main replacement, sanitary manhole repair, replacement of surfacing over trenches, and boulevard restoration.  The water main replacement successfully utilized both open trenching and directional drilling methods.  Sanitary manhole repair included reconstructing manhole benches and inverts along with installing manhole external frame seals.