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CONSIDERATION OF APPROVAL, REJECTION, AMENDMENT, AND/OR POSTPONEMENT OF CONTRACT K-2021-129: A CONTRACT BY AND BETWEEN THE NORMAN UTILITIES AUTHORITY AND CAROLLO ENGINEERS, INC., IN THE AMOUNT OF $95,090 TO PROVIDE PROFESSIONAL ENGINEERING SERVICES FOR THE GROUNDWATER BLENDING AND TREATMENT SITE EVALUATION.
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BACKGROUND: The City of Norman / Norman Utilities Authority (NUA) currently owns and operates a well field with thirty-two (32) active groundwater wells and is currently constructing nine additional groundwater wells. The water produced from the groundwater wellfield is in compliance with all primary drinking water standards as established by the Oklahoma Department of Environmental Quality and the U.S. Environmental Protection Agency (EPA). Historically, groundwater systems which are in compliance with the standards set forth in the Safe Drinking Water Act and Oklahoma Administrative Code 252:631 Public Water Supply Operation are not required to provide treatment or residual disinfectant; however, the NUA also treats and distributes surface water from Lake Thunderbird. Since the water from both the surface water source and the groundwater wells is blended in the distribution system piping, ODEQ has indicated that, in the future, the water distribution system will need to be modified such that a minimum disinfectant residual of 1.0 mg/L of chloramines (NHCL2) should be found throughout all parts of the system. Additionally, the maximum contaminant levels (MCLs) for different constituents such as arsenic and total chromium may be lowered in the future by the EPA, and a new MCL for hexavalent chromium may be established, thus requiring additional treatment of the groundwater wells. Therefore, a centralized location to blend the groundwater wells and provide the necessary well water treatment before the groundwater is blended with the treated surface water, to meet current and future regulations is necessary. The work under this contract will be to verify that possible land sites will accommodate the immediate need for the groundwater blending and disinfection but will also be able to accommodate future treatment processes as required, as regulations become more stringent.
DISCUSSION: Carollo Engineers, Inc. was determined to be the best engineer to develop preliminary layouts for the future build-out of the future groundwater treatment facility, including immediate needs and future treatment processes. Their firm has extensive experience designing treatment facilities including specialized treatment facilities that would be necessary to treat for arsenic and chromium. Additionally, Carollo successfully completed recent projects at the Vernon Campbell Water Treatment Plant, and completed the City of Norman pilot project for groundwater treatment done in 2017.
Available funds in the amount of $1,470,000 are available in Well Field Blending WTP, Design (account 31993398-46201; Project WA0214). This is sufficient to fund the proposed contract of $95,090.
RECOMMENDATION: Staff recommends the NUA approve Contract K-2021-129 in the amount of $95,090 with Carollo Engineers, Inc. for engineering services for the Groundwater Blending and Treatment Site Evaluation.