Title
SUPPLEMENTAL AGREEMENT WITH CH2M FOR WATER SUPPLY REVIEW PHASE II FEASIBILITY STUDY
COUNCIL INITIATIVE ADDRESSED:
Provide sustainable water quality & environmental infrastructure
CITY ATTORNEY REVIEW: N/A
SUMMARY STATEMENT:
On August 27, 2015, the City Council considered the recommendation of the Water Supply Review Customer Advisory Committee (CAC) to develop a new water source on the Cowlitz River utilizing Ranney collector wells, and directed staff to prepare a contract amendment to further evaluate the feasibility of developing a new water source. CH2M has developed a feasibility study scope of work to assess potential siting, capacity, water quality and treatment requirements of a future Ranney well water supply.
The scope of work includes several components with each ensuing activity based on the results of the prior activity to incrementally develop site specific information while controlling costs. Major components of work include:
· Exploratory Test Drilling (three potential sites)
· Detailed Aquifer Testing (one preferred site)
· Engineering Analysis
· Community Outreach
· Project Management
· Option for detailed aquifer analysis at a second site
Site investigation will focus on the following three locations: North Lexington (Riverside Park); South Lexington (near Rocky Point); and the Fishers Lane WTP. The potential fourth site south of the Hall of Justice was dropped from consideration due to its proximity to and potential to negatively influence Kelso’s Ranney well on the opposite bank. At each site, a small diameter test well will be drilled, followed by short duration stepped rate pumping tests and analysis of water samples to characterize the basic hydrogeology and assess general water quality.
Based on the findings of the initial site investigation, one preferred site will be identified and further evaluated to determine specific aquifer properties and more detailed water quality. A larger diameter test well will be install...
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