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OLTON <br />Reil1 50,11.'Euuor'i°. . <br />MEMORANDUM <br />Date: February 19, 2018 <br />To: Mr. Patrick Brama, Economic Development Manager <br />Mr. Time Gladhill, Community Development Director <br />Mr. Bruce Wetsby, City Engineer <br />From: Kevin P. Kielb, P.E. <br />Subject: Ramsey Parkway Center Median Analysis <br />City of Ramsey <br />Introduction <br />The City of Ramsey is reviewing the potential for revising the proposed design of the Ramsey Parkway <br />center median between Center Street and Zeolite Street. The median is currently proposed as a raised, <br />vegetated median with trees, shrubs and grasses. The total length of median area, not including the paved <br />intersections, is approximately 1,565 feet. The area analyzed is depicted on Figure 1. <br />The City is exploring the potential of creating a depressed median design, with stormwater directed to the <br />median from the travel lanes of Ramsey Parkway. <br />Based on recent conversations with City staff, infiltration is not allowed within The COR area. Depressed <br />medians will need to be designed as filtration systems, rather than infiltration systems. This adds <br />significantly to project costs when compared to a typical depressed, vegetated median. <br />Recommendations <br />The median areas through the COR are located in the moderate vulnerability Drinking Water Supply <br />Management Area. Groundwater protection will be required if the medians are depressed. <br />A table was prepared depicting estimated project costs associated with the various alternatives reviewed. <br />Either woven geotextile liner, clay liner, or EPDM rubber liner could be used for lining the median area. <br />The City should consider the benefits and costs for the various options when deciding which option to <br />select. <br />Design Considerations <br />Construction stormwater best management practices (BMPs) in the median areas include directing <br />stormwater runoff volume from the street into the median through curb cuts or pipe and depressing the <br />median area to create stormwater capture volume. Additional infrastructure is necessary to keep soils dry <br />(i.e. perforated tile) and/or overflow structures to capture and discharge flood level flows. <br />The majority of the COR is in the Moderate Vulnerability drinking water supply management area, with <br />certain sections within the Emergency Response Area. Based on conversations with the City, these areas <br />C:\Users\kevinki\Desktop\Ramsey Median\The COR - Center Median Memo 02162018.docx <br />