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WTP
Rural Water System #1 (RWS #1), Iowa’s first rural water system, was constructed in the mid‑1970s and now includes three treatment plants drawing from three water sources. Plant 1 uses the Hospers Well Field, a shallow alluvial aquifer near Sheldon, Iowa, while Plants 2 and 3 rely on shared groundwater sources near Sioux Center, Iowa, and Hudson, South Dakota. Due to the nature of the Hospers Well Field, Plant 1 was expected to eventually be classified as influenced groundwater (IGW), requiring more stringent treatment.
Need for Improvements
The IGW classification triggered a regulatory requirement for redundant filtration at Plant 1. Because Plant 1 supplies less than 20 percent of system demand, RWS #1 evaluated alternatives and selected a system‑wide solution rather than adding treatment at that location. Increasing capacity and redundancy at Plant 2 provided a more effective and flexible approach, strengthening overall system reliability and supporting future growth. DGR Engineering partnered with RWS #1 and the Iowa Department of Natural Resources to develop a compliant and strategic plan.
Solution and Outcome
At Plant 2, aging steel gravity filters—originally built in 1975 and expanded in 1992—were replaced to increase capacity from 1,850 gpm to 3,000 gpm and meet redundancy requirements. Horizontal pressure filters were selected to maximize the existing footprint and improve operational efficiency, including simplified ammonia removal. A phased construction approach maintained treatment capacity throughout the upgrade. The improvements delivered a cost‑effective, long‑term solution that enhanced reliability, met regulatory requirements, and advanced system capacity goals.
SLRW has been a trusted provider of safe drinking water for over 40 years, serving more than 2,000 customers across agricultural, residential, commercial, and industrial sectors, including bulk water sales to four communities. Historically, water treatment involved only chlorination due to the high quality of well water.
Increased system demand and the addition of new wells led to elevated iron and manganese levels, exceeding acceptable standards. This necessitated the construction of a new water treatment plant (WTP) to ensure continued compliance and service reliability.
The plant was designed with expansion in mind, including space for additional filters to meet future demand, especially given proximity to the growing Sioux Falls Metro Area. Construction occurred on the site of existing facilities. Strategic reuse of infrastructure minimized disruption and reduced costs.
Electrical system redundancy was built into the design, including separate motor control centers (MCCs) and redundant cabling, minimizing the likelihood of prolonged disruption to plant operations.
DGR Engineering worked closely with SLRW staff and leadership to determine optimal plant capacity and select treatment technologies aligned with operational preferences. The project emphasized long-term sustainability, operational flexibility, and strategic foresight.
The new WTP equips SLRW to meet current and future water quality standards, supports regional growth, and ensures reliable service for decades to come.
The rural residents around North Sioux City and Elk Point South Dakota can find as much water as they want, just by sinking a well anywhere in the Missouri River Alluvial Valley. The problem is that the “good water” in this area, which is lower in iron and manganese, is laced with radium. Rural communities like Wynstone and Sandy Meade were faced with the challenge of Radium removal to protect their customers.
Clay Rural Water System partnered with these developments and the surrounding rural customers to bring Radium Free water to over 500 homes. These residents dealt with contaminated drinking water for decades, and now have confidence in the water they are drinking. DGR Engineering worked with Clay Rural Water System to construct a reverse osmosis water treatment plant to take water with raw water combined radium 226 + 228 of 12.4 pCi/L down to below detection limits of <1.0 pCi/L. These customers have been receiving this safe drinking water now for over a decade.
The plant treats the deep well water directly with reverse osmosis without pre-treatment, even though the raw water has high iron and manganese levels. This innovative treatment approach saved significant construction and operational costs for the water system.
Construction of a bolted steel glass lined tank, foundations, and miscellaneous appurtenant work. Nominal size is 300,000 gallons, 36′ diameter, 38′ high.
The ground storage reservoir is a critical component of the water treatment process, allowing flow equalization between the filtration process and the softening system.
The City of Estherville operates an iron and manganese removal and zeolite softening facility. The plant had adequate softening capacity for growth, but had exceeded the rapid sand filtration capacity of the facility. The expansion was rated at 1,200 gpm and included the following work:
Construction of a water treatment plant expansion of 1200 gpm capacity, including concrete gravity filter cells, masonry building, yard and process piping, line shaft turbine high service and backwash pumps, horizontal split case transfer pumps, HVAC, electrical and control, site work and miscellaneous appurtenant work.