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Wastewater Treatment Facilities
Wastewater Treatment Facility
City of Huron Plans for Future
by Expanding Wastewater Treatment Facility
Project Owner:
City of Huron, SD
Unique Project Challenges:
- A desire to simplify a complicated piping network that also needed to remain in operation during construction.
- PVC resin shortage due to a catastrophic Texas storm resulted in force majeure declaration on large diameter PVC pipe.
- Navigating Covid mandates/unknowns during design followed by Covid-related supply/demand issues during construction.
- Cold weather SBR startup due to construction delays.
- A manufacturing error of a critical SBR component required creative thinking by the project team, leading to an acceptable solution.
- Corrosive soils at the site presented unique challenges with operating temperatures of the air piping and traditional pipe coatings.
Key Features:
- Upgrades to existing pretreatment facility including mechanical screen, grit removal and conveyor replacement
- Replacement and relocation of aging 18" diameter forcemain
- New anaerobic lagoon lift station
- Simplified process operations
- New continuous flow sequencing batch reactor (SBR) treatment facility
- Standby generation
- SCADA system improvements
- Peak month capacity of 5.19 MGD
- Peak day capacity of 8.0 MGD
The City of Huron, South Dakota, a community of just over 14,000 people in Beadle County, is actively preparing for its future growth. The City's existing wastewater treatment facility, which dated back to the 1930's, was nearing the end of its useful life and was undersized for the City's future needs. In addition, increasing population, more stringent regulatory effluent requirements, and the City's desire to provide treatment capacity for future economic development opportunities, prompted the need for improvements to the City's wastewater treatment facility.
The City completed a Facility Plan in 2019 to analyze future wastewater flows and loadings, summarize existing major equipment replacement needs, and to evaluate wastewater treatment alternatives. As part of the Facility Plan, the City elected to move forward with a sequencing batch reactor (SBR) treatment process. With extensive recent SBR experience, DGR Engineering was selected to work alongside the City to evaluate the various SBR manufacturers based on site visits, manufacturer presentations, and past experiences. The City determined a flow-through style SBR system to be the preferred choice, based on the jointly-developed selection criteria and the ability to meet anticipated permit limits.
In addition to constructing a new four-cell SBR, the project consisted of rehabilitation to the existing preliminary treatment building (including replacement of the existing mechanical bar screen and vortex grit removal system), HVAC improvements, gate and plate replacement, and the addition of an anaerobic cell lift station. A full-plant supervisory control and data acquisition (SCADA) system was incorporated in the project for remote monitoring.
The new facility, rated for 8.0 million gallons per day (peak day), nearly doubles the capacity of its predecessor. The expanded capacity will provide for for future population and industrial growth as well as economic development.
Construction began in 2021 and was substantially complete in 2023. The $12.8 million construction costs were financed through the Clean Water State Revolving Fund (CWSRF)
Project Approach
- Jointly worked with the client to evaluate various treatment alternatives to select an option that meet the client's treatment goals at an affordable cost.
- Evaluated several locations for the SBR location and the impact on future downstream processes for more stringent regulations.
- Analyzed existing infrastructure and process control to determine simplified alternatives.
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Control Systems & Automation
Our team of experts can cater custom SCADA solutions for any size project.
Land Acquisition Services
DGR Engineering offers a “one-stop shop” for planning, designing, permitting, right-of-way and easement acquisition services, and construction administration needs.
Water Treatment Plant Improvement
The improvements delivered a cost‑effective, long‑term solution that enhanced reliability, met regulatory requirements, and advanced system capacity goals.
Northwest Iowa
Wastewater Treatment Facility
Schleswig Wastewater Treatment Facility Moves Out of Town
Schleswig had two major decisions to make:
what type of treatment technology to construct,
and where it should be constructed.
Project Owner:
City of Schleswig, IA
Key Experience:
- Selecting a suitable site for a new treatment plant involved coordination with:
- Local landowners willing to sell land for a reasonable cost
- County engineers to provide improved site access on minimum maintenance roads
- Electrical utilities to provide new electrical service to the site - Schleswig received funding through the WWDWTFAP in the first year it was signed into legislation; a total of $775,000 in grant was awarded to six projects in Iowa in the first year
Key Features:
- New WWTF designed to treat:
- Average wet weather (AWW) flow
of 0.234 million gallons per day (MGD)
- BOD load of 276 lbs/day
- Total Kjeldahl Nitrogen (TKN) load
of 58 lbs/day - Total construction cost of $3.5 million. The project was financed through:
- SRF loan program including
Planning & Design Loan
- $300,000 CDBG grant
- $100,000 Wastewater and Drinking Water Treatment Financial Assistance Program (WWDWTFAP) grant
The City of Schleswig, Iowa is a small, German-heritage town located just north of Denison on U.S. Highway 59. To treat its wastewater the City operated a 3-cell aerated lagoon facility located in the south part of town that was originally built in 1960, with upgrades made in 1975 and 1999. Since its construction, the community has continued to expand around the treatment facility, including a golf course directly to the west and a residential housing development immediately south. Each spring as the ice would melt, the lagoons would turn over and create an odor issue throughout town, while the floating aerators provided a constant humming sound as background noise to any activities taking place near the facility.
In 2017 the City was issued a new NPDES discharge permit which contained more stringent ammonia limits as well as new E. coli limits. Similar to many small communities in Iowa, Schleswig’s aging lagoon treatment facility could not meet these new limits. It was clear that innovation was needed; hence, the City retained DGR Engineering (DGR) and began planning a wastewater treatment facility (WWTF) improvements project.
In modifying their WWTF, the City had two major decisions to make: what type of treatment technology to construct, and where it should be constructed. With input and advice from DGR, the City decided that the best option would be to build a LemTec ™ treatment system, and to move it out of town.
The City was able to purchase 7.35 acres located 2.5 miles east of town to build its new treatment facility. The LemTec™ system was chosen based on its relatively small footprint, ease of operation, and low capital and operation and maintenance costs. Ultimately, the LemTec™ system allowed Schleswig to meet the more stringent permit limits utilizing a robust, easy-to-operate, affordable technology.
The project included a new inlet screening building with a vertical mechanical screw screen and compaction system intended to remove, wash, and compact solids in the wastewater stream larger than 0.25 inches. The screening system is followed by a duplex submersible pump lift station, both located at the existing treatment site. The lift station pumps the screened influent through 2.5 miles of 8” forcemain to the new treatment site.
Many WWTFs that struggle to meet ammonia limits have more issues in the cold winter months than in the summer. This is because at a wastewater temperature of 60°F, the nitrification rate at which bacteria treat ammonia begins to decline, and at a wastewater temperature of 50°F the treatment efficiency is reduced by half.
The LemTec™ system helps combat this phenomenon in two ways: first, the insulated lagoon covers help retain heat in the system; second, the fixed media in the polishing reactors provides greater surface area to allow a larger population of nitrifying bacteria to grow and treat ammonia.
The LemTec™ system at the new treatment site consists of two aerated treatment lagoons which are covered with insulated, floating covers to retain heat and increase treatment efficiency.
The aerated lagoons are followed by small polishing reactors which contain fixed media to provide additional ammonia treatment. Effluent from the polishing reactors is disinfected through a UV disinfection system for treatment of E. coli prior to discharge to the receiving stream.
The system began initial start-up in mid-December 2021, and after a slow start-up process due to a cold winter and spring, is currently treating the wastewater to non-detectable ammonia concentrations (< 0.5 mg/L).
The City is currently working on filling in one of the old treatment lagoons, and the floating aerators and baffles were removed from the other treatment lagoon as a part of this project. A walking trail winds past the old treatment lagoon, and now instead of nuisance odors and loud humming from the floating aerators, residents can enjoy a serene view of a pleasant, quiet water feature while their wastewater is being effectively treated outside of town.
Featured Projects
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Control Systems & Automation
Our team of experts can cater custom SCADA solutions for any size project.
Land Acquisition Services
DGR Engineering offers a “one-stop shop” for planning, designing, permitting, right-of-way and easement acquisition services, and construction administration needs.
Water Treatment Plant Improvement
The improvements delivered a cost‑effective, long‑term solution that enhanced reliability, met regulatory requirements, and advanced system capacity goals.
Northwest Iowa
Wastewater Treatment Facility
NEW Wastewater Plant
replaces aging infrastructure
Project Owner:
City of Sheldon, IA
Key Experience:
- Maintaining the use of the existing facility during construction of the new one
- Cooperation with existing business and residences that would be affected by the location of the new facility
Key Features:
- New continuous flow sequencing
batch reactor (SBR) wastewater
treatment facility - Pretreatment including mechanical bar screen and non-mechanical grit removal
- UV disinfection
- 5.3 million gallons of waste treated daily
- 1,000 kW backup generator
- Automated systems
- New outfall and discharge location
Sheldon, Iowa is a community of 5,200 people located in the northwest corner of the state. The City’s existing wastewater treatment facility was nearing the end of its useful life and was undersized for the City’s current population. Additionally, a new National Pollution Discharge Elimination System (NPDES) permit required advancements in treatment which the old facility could not provide.
DGR Engineering (DGR) worked jointly with the City to evaluate multiple treatment alternatives which included updating the existing water treatment plant. Ultimately, the selection of sequencing batch reactor (SBR) was made, based on cost, operational flexibility and convenience. The option of modernizing the existing plant was rejected because the cost would have been nearly double that of a new facility.
The new plant, rated for 5.3 million gallons per day (MGD) peak day, doubles the capacity of its predecessor. It is adequate for future population growth as well as economical development with industrial growth potential.
Start up of the new plant took place in mid-July and old infrastructure is currently being demolished. The $9.5 million construction costs were funded with revenue bonding and tax incremental financing (TIF) and utilized City owned property adjacent to the existing facility. Cooperation with existing businesses and residences affected by the location of the new facility was essential to project success. The facility is expandable for future treatment requirements, and will serve the City’s needs for many years into the future.
Featured Projects
- All
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Control Systems & Automation
Our team of experts can cater custom SCADA solutions for any size project.
Land Acquisition Services
DGR Engineering offers a “one-stop shop” for planning, designing, permitting, right-of-way and easement acquisition services, and construction administration needs.
Water Treatment Plant Improvement
The improvements delivered a cost‑effective, long‑term solution that enhanced reliability, met regulatory requirements, and advanced system capacity goals.
Northwest Iowa
Wastewater Treatment Facility
Orange City Prepares for the Future
Addition of mechanical treatment facility meets capacity and compliance
Project Owner:
City of Orange City, IA
Key Features:
- New flow-through sequencing batch reactor (SBR) wastewater treatment facility
- Preliminary treatment includes spiral screening and grit removal
- UV disinfection
The City of Orange City, IA, population approximately 6,000, received an Administrative Consent Order from the Iowa Department of Natural Resources for effluent ammonia violations of their National Pollution Discharge Elimination (NPDES) permit in 2015. The City was required to make improvements to their wastewater treatment plant to bring them into compliance with effluent limits. In turn, the City evaluated treatment options to not only meet existing permit limits, but also to comply with anticipated future limits including provisions for the Iowa Nutrient Reduction Strategy.
DGR Engineering (DGR) worked with the City to evaluate alternatives, which included constructing a sequencing batch reactor (SBR), mixed bed biofilm reactor (MBBR), retention and land application, activated sludge, or submerged attached growth reactor (SAGR).
The evaluation considered capital costs, long-term operation and maintenance costs, operational flexibility and expandability. After consideration and numerous site visits, the City ultimately determined a flow-through style SBR system to be the preferred choice based on the selection criteria and the ability to meet anticipated permit limits.
Preliminary treatment includes a spiral screen and vortex grit removal system. An ultraviolet (UV) disinfection system was also included to meet effluent disinfection requirements. A full-plant supervisory control and data acquisition (SCADA) system was incorporated in the project for remote monitoring.
The existing facility consisted of a six cell aerated lagoon system which included an industrial pretreatment cell with surface aerators, three aerated cells with diffused air, along with two quiescent cells.
The new system will utilize two of the existing lagoon cells’ flow equalization and sludge storage prior to land application. During peak flow events, the facility can split flow to utilize the dedicated lagoon for equalization and then send back influent wastewater through the plant when flows subside.
The facility was designed to treat a total flow of 2.45 million gallons per day (MGD) to accommodate projected 20-year domestic and industrial growth.
The new facility was designed for an increased population of 6,500. The improvements made the facility easily expandable for future needs and was designed with impending nutrient limits in mind.
Due to the complexity of the new facility, the required operator certification increased from a Grade II to a Grade IV certification. DGR Engineering worked closely with the City and IDNR to determine a pathway for expedited training and certification of existing staff.
Total project cost was $9.9 Million. The City used local bonds for the project costs.
Featured Projects
- All
- Aviation
- Civil
- Electrical Power
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Control Systems & Automation
Our team of experts can cater custom SCADA solutions for any size project.
Land Acquisition Services
DGR Engineering offers a “one-stop shop” for planning, designing, permitting, right-of-way and easement acquisition services, and construction administration needs.
Water Treatment Plant Improvement
The improvements delivered a cost‑effective, long‑term solution that enhanced reliability, met regulatory requirements, and advanced system capacity goals.
Northwest Iowa
Wastewater Treatment Facility (SBR)
Wastewater facility design
Involves Planning for growth
and pending regulations
Growing Dell Rapids community builds
system that will foster future growth
Project Owner:
City of Dell Rapids, SD
Key Features:
- New Sequencing Batch Reactor (SBR) wastewater treatment facility
- Pretreatment includes spiral screen and grit removal
- Ultraviolet disinfection
The City of Dell Rapids, SD, population 3,705, was under a construction order as part of their new Surface Water Discharge Permit. Effluent ammonia levels over their permit limits had caused several violations and the South Dakota Department of Environment and Natural Resources (DENR) required upgrades to their system to address these issues.
The City completed a study to evaluate several treatment processes which included Submerged Attached Growth Reactor (SAGR), conventional activated sludge, extended aeration, trickling filters, membrane bioreactor, moving bed biofilm reactor (MBBR) and Sequencing Batch Reactor (SBR). The evaluation considered capital cost, long-term operation and maintenance, along with future discharge limits. With consultation from DGR Engineering (DGR), the City ultimately selected the SBR treatment process which enabled them to adapt easily to future permit limits. Cost, ease of operation and the ability to be easily expanded to meet future growth were factors in the decision.
The previous treatment process utilized an aeration lagoon, followed by a series of facultative lagoons. With a total project cost of $4.7 million, the new SBR system utilizes the existing aeration lagoon for equalization and another lagoon cell for sludge storage, which reduces the cost of the project for the City and provides more operational flexibility. The equalization basins also reduce the peak design requirements of the new treatment equipment because the peak flows can be diverted during a large rain event until the flows subside to or below the design capacity of the SBR system.
The SBR treatment process provided a cost-effective solution to meet future ammonia limits as well as being set up for anticipated total phosphorus and total nitrogen limits. The DENR was consulted during the design process to help establish anticipated future limits. Once these limits are implemented, the treatment cycle can be modified to meet total nitrogen limits, while a chemical feed system can also be added to meet future phosphorus limits.
DGR designed the system to be easily expandable if the City grows beyond the original design capacity. The new facility has a 750,000 gallon-per-day capacity and was constructed with a 20-year design life, using an estimated population of 5,900.
Featured Projects
- All
- Aviation
- Civil
- Electrical Power
- Survey
- Water & Wastewater
Control Systems & Automation
Our team of experts can cater custom SCADA solutions for any size project.
Land Acquisition Services
DGR Engineering offers a “one-stop shop” for planning, designing, permitting, right-of-way and easement acquisition services, and construction administration needs.
Water Treatment Plant Improvement
The improvements delivered a cost‑effective, long‑term solution that enhanced reliability, met regulatory requirements, and advanced system capacity goals.
Northwest Iowa