The Environmental Protection Agency (EPA) conducted an environmental review of the proposed water treatment facility at the Mint Farm and have issued a preliminary determination that the project will not results in significant adverse effect (direct, indirect or cumulative) to the human and natural environment and meets all requirement of applicable federal, state and local laws, regulations, statues and Executive Orders and is consistent with the Cowlitz County Comprehensive Plan and Growth Management Act.
As a recipient of federal funding, the Mint Farm Water Treatment Plant project is subject to federal NEPA compliance with EPA acting as the lead review agency. The Environmental Impact Document (EID) contains a detailed description of the proposed project (preferred alternative), the no action alternative and other alternative considered but rejected. It evaluates the effect the project may have on the human and natural environment including wetlands, coastal zones, archaeological and cultural resources, floodplains, endangered species, air and water quality and proposes mitigation measures to minimize the potential impact.
A brief summary of a follow-up 4-week pilot study performed in May, 2010 to confirm the performance of greensand granular media filtration using water drawn from deep monitoring well DW-9. The raw water quality at DW-9, located at the site of the future production wells, is lower in iron, manganese and arsenic compared to the original Prudential Blvd test well.
A report summarizing the field work and results of the geotechnical study, including sub-surface investigation, exploratory borings and laboratory testing, for the proposed Mint Farm Regional Water Treatment Plant and associated transmission main to connect the plant to the City’s existing distribution system.
Draft Preliminary Design Report - March 2010
The PDR is a comprehensive report which provides a history of the water supply project, why it is necessary, what has been done to investigate it, and a description of the new facilities and method of treatment proposed to develop a groundwater source at the Mint Farm. Part 1 (Basis of Design) provides background about the existing water treatment plant and why groundwater is being considered as an alternative source of supply. It describes pilot study efforts done to confirm the groundwater could be effectively treated, the preferred method of treatment, and provides a preliminary layout of the proposed water treatment plant, processes and wellfield. Part 2 (Hydrogeology, Water Quality and Wellhead Protection) provides a detailed characterization of the deep aquifer, associated water quality, and how it can be protected. Subsurface investigations and complex modeling is used to interpret how the aquifer behaves, simulate the pattern of groundwater flow and evaluate the impact of long-term pumping. Part 2 also describes what is required of a Wellhead Protection Program to protect the source from potential contamination at the surface. Part 3 (Environmental Permitting) describes the initial findings and on-going work associated with the National Environmental Protection Act (NEPA) permitting process and archaeological investigation required as part of the project.
Detailed report describing the environmental investigation of the Mint Farm Industrial park and related findings. The focus of the investigation was to identify the potential for off-site or on-site environmental conditions to impact development of the deep aquifer and proposed well field. The study included an in-depth review of historical activities, file review with regulatory agencies, site reconnaissance and extensive field and lab work to collect and analyze numerous soil samples and groundwater samples throughout the site.
01-04-10 Human Health Risk Assessment
A focused assessment of the water quality and potential risk to human health, if any, posed by the three raw water sources available to this area. Untreated samples collected from the Cowlitz River, Columbia River and Mint Farm deep aquifer were analyzed for more than 300 analytes including contaminants currently regulated by state and federal drinking water standards, contaminants expected to be regulated in the future, emerging contaminants (pharmaceuticals and personal care products), and chemicals specific to local industry. This report compares the three sources and evaluates whether the proposed groundwater is a safe source of drinking water supply.
11-21-2009 - Project Map
A concept map showing the basic site layout for the new water treatment plant and proposed well field.
11-21-2009 - Vicinity Map
A concept map showing the basic site layout for the new water treatment plant and proposed well field.
10-31-2009 Monitoring Well Location Map
A map showing the locations of the deep and shallow monitoring wells in and around the perimeter of the Mint Farm Industrial Park.
09-04-2009 Deep Monitoring Wells Construction Well Logs
A detailed record of the geologic formation of deep monitoring wells DW-1 through DW-9 based on visual inspection of the cuttings produced during drilling and physical measurement made by instruments lowered into the hole (E-Log).
09-02-2009 Mint Farm Groundwater Granular Media Study Report
The results of a 5-week pilot study using generic equipment to treat raw water pumped from the Prudential Blvd test well and determine whether iron, manganese and arsenic could be successfully removed using three types of conventional granular media.
05-02-2009 Mint Farm Groundwater Pilot Study Protocol
The plan developed for the pilot study which describes the pilot study equipment and how it will be operated, establishes goals for the treated water quality, identifies the oxidants which will be used, and outlines the sampling and analysis plan for the raw water and treated water.
04-28-2009 Water Quality Sampling and Analysis Protocol
A plan describing where and how three different types of samples will be collected – soil samples from the Mint Farm Industrial Park, groundwater samples from the Mint Farm aquifer (deep and shallow), and other potential surface water sources (Cowlitz and Columbia Rivers). Also describes what each type of sample will be tested for based on current regulation, emerging contaminants which may be regulated in the future and unregulated contaminants common to historical and industrial activity in and around the Mint Farm.
04-03-2009 Shallow Monitoring Well Construction Report
A summary of the drilling activity for the construction of the first set of shallow monitoring wells. Provides the location, drillers well report, construction details and geologic log for wells SW-1 through SW-7.
05-05-2008 - GSI Environmental Review
A third party environmental review of the area near the proposed well field in the Mint Farm looking for existing potential contaminant sources due to industrial and commercial operations, and existing wells with poor surface seals. The report evaluates the potential risk of contamination to the deep aquifer from those potential sources.
01-09-2008 Columbia River Water Quality Report
Laboratory report with results of the analysis of untreated water samples collected from the Columbia River. Reports raw data from analysis of inorganic compounds (IOC’s), volatile compounds (VOC’s), synthetic organics compounds (SOC’s), herbicides and some unregulated contaminants.
12-14-2007 - GSI Peer Review
Provides a second opinion of the groundwater evaluation provided by Robinson, Noble & Saltbush in their 01-2007 Prudential Blvd Test Well Report which included preliminary conclusions about the Mint Farm aquifer based on the original test well. The GSI peer review focuses on whether the aquifer is productive enough to meet the City’s projected water demand and whether that supply can be sustained. Also provides discussion of the basic groundwater quality and issues related to siting the well field in an industrial area.
01-2007 PRUDENTIAL BLVD TEST WELL & WATER QUALITY DATA
A summary of the construction of the Prudential Blvd test well (formerly Weber Ave test well) which was the first exploratory well drilled in the Mint Farm. Describes the drilling, construction, testing, geology, hydrogeology and water quality at this location.
