case studies Grimes, IA


Grimes, IA

Operations and Maintenance – Water & Wastewater Utility O&M

Owner Name: City of Grimes, Iowa
Service Categories:
O&M: Drinking Water,
O&M: Wastewater & Reclamation,
Consulting,
Infrastructure Rehabilitation
Project Name: Operations and Maintenance – Water & Wastewater Utility O&M
Contract Term: July 2014 - Current

On July 1, 2014, USW Utility Group (USWUG) began a five (5) year contract with the City of Grimes that was awarded through the competitive bidding process. USWUG’s contract requires operations, maintenance and overall management of its water and wastewater treatment facilities. Also included is distribution and collections system maintenance and repair along with monthly meter reading services. The City of Grimes is a suburb of Des Moines and is one of the fastest growing communities in the country that needed to address treatment capacity; quality and storage demands commensurate with its rapid growth.

When USWUG’s contract began on July 1, 2014, the water treatment system consisted of a 1.73 mgd lime softening plant fed by three shallow wells with a specified pump capacity of 600 GPM each. These shallow alluvial wells are high in iron and manganese and produce finished water total hardness of 300 mg/l as CaCO3.  Storage consists of two (2) ground storage tanks of 400,000 and 1,000,000 gallons, respectively.

The Grimes wastewater treatment plant is a Class III extended aeration facility with a design capacity of 2.13 MGD. With the growing community and an aggressive commercial business campaign by the Chamber of Commerce, the WWTP consistently reaches design capacity along with solids overloading.  The collection system has high levels of inflow and infiltration.

Per standard company procedure, USWUG conducted a comprehensive review of the utility system’s operational practices to develop and prioritize operational, financial, and regulatory necessities and goals. Once the review was completed, a Statement of Existing Conditions (SOC) Report was completed, detailing the utility condition, short and long-term recommendations, timelines and projected costs associated with corrective actions. Based on the findings of the review, USWUG created a plan for daily operations and schedule for capital improvements.

In 2014, Well 201, drilled in the deep Jordan aquifer was completed on the water treatment plant site to provide additional capacity of 1,200 gpm. Well 201 was brought online in November 2014 and blended 50/50 with the shallow wells. The blend of these wells created additional water chemistry challenges. Through life-cycle cost analysis, USWUG explored many treatment options that would meet the growing demand and provide a higher finished water quality using the available source water. Through successful pilot studies, USWUG recommended reverse osmosis (RO) as the preferred treatment. In the winter of 2015/2016 the Iowa Department of Natural Resources designated the City of Grimes “Emergency Status” to provide expedited water demand relief by allowing the City to design and construct a 1.6 MGD Harn RO system in an existing facility adjacent to the lime softening treatment plant. Reverse osmosis skid #1 was completed and brought online in June 2016. Skid #2 was completed in June 2017. In 2018 the construction of a new building that will house up to seven additional Reverse Osmosis treatment skids will begin. This building will also provide additional high service pumps, chemical treatment areas along with operation and maintenance staffing facilities. Upgrades to the existing lime softening plant will also take place.

Well 1, drilled in 1966 from the deep Jordan aquifer, was converted into an aquifer storage and recovery (ASR) well. Injection of 60 to 80 million gallons of water is anticipated during the winter of 2017/2018. This water will be used as a supplement during high demand summer conditions. In addition, the City has obtained land to construct a new 2.0 million-gallon (MG) water tower to be completed in 2019. An additional 1.5 MG elevated storage tank is planned for future distribution storage capacity.

In 2015 construction, in addition to numerous upgrades to the water and wastewater treatment plants, a peak flow diversion structure was constructed at the wastewater plant headworks. Two 12.5 MGD screw pumps were installed to feed the equalization basin during high flow conditions. The Gateway lift station was upgraded with new SCADA controls and telemetry systems. To help address inflow and infiltration problems, the force main from one of the large lift stations was replaced along with rehabilitation of the main 48” lines conveying wastewater to the WWTP.  In 2019 construction will begin on phase three of the WWTP.  This phase will double the size and capacity of the existing WWTP to meet the demands of the rapidly growing utility.

Through monthly progress meetings and facility planning, USWUG continues to work with the City of Grimes and the City’s Engineer of Record to meet the needs of a rapidly growing community. USWUG has a staff of eight (8) total team members assigned full-time to the City of Grimes facilities that has effectively met the City’s goals of reduced operational cost, increased operational efficiency, and compliant water and wastewater treatment services.  The City has not experienced any compliance issues, violations of EPA or State requirements, or service delivery problems since the transition over to USWUG as its Utility Partner. The City of Grimes has fully engaged USWUG’s Engineering and Consulting services to assist their Engineering Firm with meeting their multi-year, 3-Phase water and wastewater utility expansion, which has an estimated total cost of $33,350,000.

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