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<br /> <br />Page 1 of 2 <br /> <br />Joint Development Authority <br /> TCAAP Redevelopment Project <br /> <br />DATE: March 29, 2018 <br /> <br />TO: Joint Development Authority Board of Commissioners <br /> <br />FROM: Administrator Olson <br />Beth Engum P.E., Project Manager, Ramsey County <br /> <br />SUBJECT: TGRS Optimization Study Update <br /> <br /> <br />The United States Army submitted a draft final report of the TCAAP Groundwater Remediation System <br />(TGRS) Optimization Study (formally titled TCAAP Operable Unit Remedy Review) to regulators at the <br />Environmental Protection Agency (EPA) and Minnesota Pollution Control Agency (MPCA). Draft final <br />reports are available through Amy Hadiaris at MPCA. <br /> <br />County project staff reviewed the document and offer the following summary of report findings as they <br />relate to the Rice Creek Commons (RCC) redevelopment site: <br /> <br />• The primary objective of the study was to understand what changes can be made to source <br />control operations and the TGRS that would subsequently improve conditions in the drinking <br />water sources via a combination of both short-term and long-term improvement steps. <br />• Operation of the TGRS will continue; however, optimization is recommended to adapt <br />groundwater extraction operations to enhance contaminant (TCE and 1,4-dioxane) removal and <br />potentially shift the system strategy to focus on mass recovery as opposed to the current TGRS <br />prescriptive flow rate. <br />• As a short-term measure, the study identified installing additional extraction wells at Sites D, G, <br />and I to enhance source removal. Site I, near former Building 102, is the only site of the three <br />that is located within the RCC redevelopment. In this location, two extraction wells (SC1 and <br />B13) may be abandoned and replaced with one well located both for optimal contaminant <br />removal and accommodation of redevelopment features. Given that this is the only study <br />recommendation with direct impact to RCC, it is important the redevelopment team remain part <br />of the conversation should the Army decide to implement source control changes at Site I. See <br />attached map. <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />AGENDA ITEM 6A <br /> <br />MEMORANDUM