Agenda - Public Works Committee - 01/19/2021

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Public Works Committee 5, 3, Meeting Date: 01/19/2021 By: Bruce Westby, Engineering/Public Works Title: Consider Water Treatment Plant Site Selection Recommendation Purpose/Background: Purpose: The purpose of this case is to consider providing a Water Treatment Plant (WTP) site selection recommendation to the City Council. Background: The source water for the City of Ramsey's water supply system is groundwater obtained from the Tunnel City-Wonewoc (TCW) aquifer through eight municipal water supply wells. In 2019, concentrations of manganese ranged from 0.02 milligrams per liter (mg/L) to 0.37 mg/L. In 2019 the Minnesota Department of Health (MDH) had a Health Based Value (HBV) for manganese of 0.100 mg/L for bottle feeding infants, and 0.300 mg/L for anyone over 1-year old. Four of Ramsey's eight water supply wells exceeded the MDH HBV for manganese in 2019 so MDH recommended that the City develop plans to reduce manganese concentrations in the water supply system. In addition to the potential health concerns with manganese, Ramsey's drinking water also exceeds the Secondary Standards for iron and manganese. Water with concentrations of iron and manganese above the Secondary Standard causes aesthetic problems including red and black staining of plumbing fixtures, laundry, sidewalks, buildings, etc., as well as taste complaints. The most cost effective process for removing manganese and iron from drinking water is chemical oxidation followed by sand filtration. Incorporating these processes will require construction of a water treatment plant. The City therefore hired an engineering consultant to prepare a Feasibility Report to ensure our groundwater aquifer has enough capacity to support our future needs, to prepare a water system model, to explore preliminary design options and estimated costs for a WTP, and to evaluate 4 optional sites. Based upon an analysis of Ramsey's projected 2040 water demand, the capacity of the proposed water treatment plant is 10 million gallons per day (MGD), with an ultimate expansion capacity of 20 MGD. This generally requires a minimum site area of 3.5 acres. The following four potential water treatment plant sites were identified and evaluated. • Fire Station Site - 3.2 acres undeveloped private property immediately south of Fire Station #1. • Public Works Site - 3.5 acres City -owned undeveloped property immediately north of the new Public Works facility, which is currently under construction. • Water Shop Site - 3.5 acres City -owned property immediately west of Jasper Street where the current Public Works Utilities Shop is located. • Vacant City Property Site - 4.1 acres City -owned undeveloped property immediately east of Ramsey Boulevard and north of the BNSF rail line. The locations of all four potential WTP sites are shown in relation to each other in attached Figure 1. Each site is shown in more detail in attached Figures 4 — 7. The preliminary estimated project cost for constructing the WTP as proposed within the Feasibility Report is $31,890,000. Project costs include the capital cost plus contingency, administration, and engineering costs.