- Public Works
- Engineering Division
- Mint Farm Groundwater Project
- Project Information & Reports
Project Information & Reports
May 18, 2017
Silica Removal Alternatives Evaluation (PDF)
A report describing treatment technologies for silica removal and including a discussion of capital, operating and annual maintenance costs.
Silica Removal Alternatives Attachments (PDF)
A technical report containing results of bench testing done to evaluate treatment options for silica removal.
August 1, 2017
Softening Alternative and Baltimore Street Water Quality Evaluation (PDF)
A report summarizing the results of numerous water quality investigations and mitigation strategies.
- Appendix A - Ice Pigging Report (PDF)
- Appendix B - Dissolved Oxygen Addition Cost Estimate (PDF)
- Appendix C - Phosphate Bench Test Plan (PDF)
- Appendix D - Environmental Protection Agency Sample Analysis Brief (PDF)
- Appendix E - Bottled Water Report (PDF)
- Appendix F - Silica White Paper (PDF)
- Appendix G - Aluminum Coagulant Jar Test Plan (PDF)
- Appendix H - Nitrogen Study (PDF)
- Appendix I - Bench Scale Chlorine Demand and Decay Study (PDF)
- Appendix J - Organic Nitrogen Removal (PDF)
- Appendix K - Home Profiling (PDF)
- Appendix L - In Home Dissolved Oxygen Trials (PDF)
March 9, 2016
Organic Nitrogen Removal (PDF)
A technical memorandum explaining the test methods and results of work done to evaluate interim measures to remove organic nitrogen which could help address issues related to chlorine taste and odor.
April 27, 2015
Flavor Rating Assessment (PDF)
Results of taste and odor testing performed by Seattle Public Utility to rate Longview's drinking water for offensive taste and odors.
June 25, 2015
Chlorine Demand and Decay (CDD) Study (PDF)
A comparison of chlorine demand and decay characteristics of each production well to determine which well has the most stable free chlorine residual and least tendency to result in combined chlorine species.
July 29, 2015
Results of water quality profiling done at two residential homes to better understand if the chemistry of the water changes between the distribution system main and the customer's tap.
June 6, 2014
Provides background on silica and summarizes treatment options to remove it. This paper is not intended to provide an exhaustive review on silica but does provide an overview of the key aspects of silica chemistry which are necessary to evaluate the feasibility of treatment options for silica removal.
November 18, 2013
A report submitted to the Washington State Department of Health in compliance with the Groundwater Rule describing the results of a chlorine contact time tracer study and demonstrating CT6 for 4-log treatment at the Mint Farm Regional Water Treatment Plant.
August 23, 2012
Water System Start-Up Plan (PDF)
Start-up of the new Mint Farm Regional Water Treatment Plant will change the direction of flow in certain areas of the distribution system. Flow reversal and the change from a surface water to a groundwater can create problems. This plan describes measures taken to prevent issues including:
- Increased Monitoring
- pH Adjustment
- Reservoir Cleaning
- Use of Citizen Sentinels to Provide Early Detection
- Water Modeling
September 14, 2012
Mint Farm Wellfield Source Approval (PDF) (less appendices)
Mint Farm Wellfield Source Approval (PDF) (with full appendices)
In accordance with Washington Administrative Code 246-290-139, this report was submitted to the Washington State Department of Health for regulatory approval of the Mint Farm wellfield. It summarizes the following for each of the four wells:
- Engineering and Hydrogeological Evaluation
- Initial Planning
- Well Logs and Water Quality Information
March 2, 2011
National Environmental Policy Act Amendment for Pipeline Re-Alignment (PDF)
Due to difficulty in acquiring railroad easements, an amendment was required for an alternative alignment of transmission main. Except for its location, the details of the transmission main as described in the original Environmental Information Document remain the same.
March 14, 2011
State Environmental Policy Act Amendment for Pipeline Re-Alignment (PDF)
In accordance with State Environmental Policy Act (SEPA) rules and Washington Administrative Code 197-11, the change in alignment for the transmission main was also submittal for SEPA review.
March 29, 2011
Mint Farm Water Treatment Plant Corrosion Control Report (PDF)
The Environmental Protection Agency published the Lead and Copper Rule (LCR) in 1991 to reduce lead and copper levels in water by reducing the corrosivity of the water in the distribution system and reducing the corrosion of plumbing materials containing lead and copper. This report presents the City’s strategy to control corrosion in compliance with the LCR.
January 4, 2010
Human Health Risk Assessment (PDF)
A water quality assessment of the available water supply sources - Cowlitz River, Columbia River and Mint Farm aquifer. This report compares the three sources and evaluates whether the groundwater source is a safe supply of drinking water.
March 8, 2010
Environmental Site Assessment (PDF)
Detailed investigation of work done to identify the potential for on or off site conditions to impact the Mint Farm well field. Includes an in-depth review of historical activities, file review with regulatory agencies, site recon, and extensive analysis of soil / groundwater samples taken from the Mint Farm.
Preliminary Design Report
A comprehensive report describing the history of the water supply project, why it's necessary and what's been done to investigate it.
- Executive Summary (PDF)
- Part 1 - Basis of Design (PDF)
- Part 2A - Hydrogeology Report (PDF)
- Part 2B - Water Quality Report (PDF)
- Part 2C - Wellhead Protection Report (PDF)
- Part 3 - Environmental Permitting (PDF)
- Appendices A to G (PDF)
- Appendices H to R (PDF)
- Appendices S to W (PDF)
- Appendices X to Y (PDF)
June 7, 2010
Mint Farm Water Treatment Plant Geotechnical Report (PDF)
A report summarizing sub-surface investigation, exploratory borings and lab results for the Mint Farm Regional Water Treatment Plant and associated transmission main to connect the plant to the City’s distribution system.
July 19, 2010
A pilot study to confirm performance of greensand filtration using water drawn from deep monitoring well DW-9, located nearer to future production wells. Dw-9 is lower in iron, manganese and arsenic than the Prudential Blvd test well.
August 13, 2010
National Environmental Policy Act Environmental Impact Document (EID) (PDF)
A detailed description of the Mint Farm Regional Water Treatment Plant project, the no action alternative and other alternatives considered but rejected. It evaluates:
- Air and Water Quality
- Archaeological Resources
- Coastal Zones
- Endangered Species
- How to Mitigate Impacts
- Human and Environmental Effects Including Wetlands
August 13, 2010
National Environmental Policy Act Finding of No Significant Impact (FONSI) (PDF)
The Environmental Protection Agency conducted a review of the Mint Farm Regional Water Treatment Plant project and issued a determination that the project will not result in significant adverse effect, 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.
April 28, 2009
Water Quality Sampling and Analysis Protocol (PDF)
A plan describing where and how water and soil samples will be collected to evaluate the Mint Farm source. Includes an analyte list for testing based on regulation, emerging contaminants which may be regulated in the future and unregulated contaminants common to historical and industrial activity near the Mint Farm.
May 2, 2009
Mint Farm Groundwater Pilot Study Protocol (PDF)
The plan developed for water treatment trials describing the pilot study equipment, how it will be operated, treated water quality goals, and outlining the sampling and analysis plan for the raw and treated waters.
September 2, 2009
Mint Farm Groundwater Granular Media Study Report (PDF)
The results of a pilot study to treat raw water pumped from the Prudential Boulevard test well and to determine whether iron, manganese and arsenic could be removed using three types of conventional granular media.
January 9th, 2008
Columbia River Water Quality Report (PDF)
Laboratory results of the analysis of untreated water samples collected from the Columbia River. Includes inorganic compounds, volatile compounds, synthetic organics compounds, herbicides and some unregulated contaminants.
May 5, 2008
GSI Environmental Review (PDF)
A third party environmental review of the area near the proposed Mint Farm wellfield looking for existing potential contaminant sources due to industrial and commercial operations, and evaluating the risk of potential contamination.
May 7, 2008
A report identifying deficiencies, needed improvements, cost estimates, and construction schedule for possible rehab of the Fishers Lane water treatment plant.
- Constructability Study (Part 1 of 2) (PDF)
- Constructability Study (Part 2 of 2) (PDF)
- Constructability Study (Table 5) (PDF) - Rehab Cost Escalation Planning Table
- Constructability Study (Phases) (PDF) - Schedule of Proposed Improvements
Prudential Boulevard Test Well Report (PDF)
A summary of the Prudential Boulevard test well (formerly Weber Avenue test well) which was the first exploratory well drilled in the Mint Farm. The report describes the following of the location:
- Water Quality
September 4, 2007
Value Engineering Study
A review of water quality alternatives focusing on options to rehabilitate Fishers Lane or relocate the source and treatment to the Mint Farm Industrial Park.
- Value Engineering Study (Part 1 of 3) (PDF)
- Value Engineering Study (Part 2 of 3) (PDF)
- Value Engineering Study (Part 3 of 3) (PDF)
December 14th, 2007
A second opinion of the groundwater evaluation provided in the January 2007 Prudential Boulevard Test Well Report. The peer review focuses on whether the aquifer is productive enough to meet projected water demand, whether the supply can be sustained, and includes a discussion of issues related to siting wells in an industrial park.