CCA Draft Final Report 72-Hour Well 6 Water Test Conducted July 13-16, 2020 September 3, 2020 1
Histor orical B Backgrou ound: CCA Has Been Pursuing An Increase In Water Capacity For 5+ Years: • In 2016 CCA BOD approved an Engineers Proposal for Well 5 based on a reference to a 2016 CCA Water System Analysis of Alternative September 2016. “Conclusion: It is recommended that the system select Alternative #2: using an existing 6” test well and drill an additional 8” well in hopes of a capacity of 189 gpm – 278 gpm. The total estimated cost for this alternative is $549,300 - $579,300.” • Wells 5 (DOH Source 06 – 6” dia.) and 6 (DOH Source 07 – 8” dia.) were installed south of Clear Lake in 2015 and 2017. Many municipalities operate their water systems with similar redundancies and distributed source areas so that the likelihood of complete water service disruption due to a catastrophic event is minimized. 1
Why y the he 72 72-Hou Hour T Test ? ? • Previous Tests: Well 5 - tested in 2015 with an 8-hr constant rate pumping test at 252 gpm. Well 6 - tested in 2017 with a 24-hr constant rate test at 500 gpm. • Results of the 24-hour test were open to interpretation due to a rise in water level • DOH requested additional investigation requiring the 72-hr constant rate pumping test to address, answer & resolve two fundamental Questions: 1. Is the groundwater under the influence of surface water 2. Is the aquifer an unconfined or leaky confined aquifer? 2
Test Requ quirements: • Scheduling and conducting this test required an increase in infrastructure beyond the existing pumping and electrical capabilities at the Well 5/6 location. • It required a new pump be purchased and installed. The right pump would be a 3-phase power pump. Life-cycle operating costs and reliability favored 3 phase over single phase power. NWWS confirmed through PSE that 3 phase power was within 600’ radius making the build out cost reasonable if the pump plant was to become permanent. • NWWS and PGG created and obtained approval of a formal pump test plan by the DOH. • It was specifically written to obtain the answers DOH required to determine site acceptability. 3
Test Requ quirements Cont’d: • Accomplishing the test required support from the following: Northwest Water Systems (NWWS) - Pump Plan –Engineer of Record for System Design – Technical continuity of knowledge base Tacoma Pump and Drill (TPD) - technical equipment and personnel Puget Sound Energy (PSE) - investigation of power Emerald City Fence Company – Temp Security Fence Pacific Ground Water Group (PGG) – Hydrogeologic expertise Consultant - technical coordination and review CCA Staff – Set up/ 72-hour on-site monitoring 4
Test Pre Preparation: • All approved processes & plans were utilized to create a comprehensive Pre-start Checklist. Contractually required prior to start of the test. • CCA Board approved all contracts; the test was set for a start date of July 13, 2020. Data collection started July 6, 2020. • PGG installed calibrated instruments to monitor water levels in both wells and Blue Lake. • CCA GM and Maint. Mgr. prepared an alternate staffing schedule to ensure the site was monitored 24hr/day from start to completion. Additionally, employees were trained by the Hydrogeologist to monitor water levels, 5 take, measure, and record readings during their shifts.
Test Prepa paration C Cont’d: • TPD installed a new pump into the 8” well and attached all equipment required for operation and testing including 300' discharge line. • All materials brought into the site were inspected to ensure they were the materials ordered/paid by CCA. • CCA Site preparations began the weekend prior to the Monday, July 13, 2020 anticipated start date: The GM brought a personal trailer to the site to house employees. A fence was installed around the work site for nuisance security. A portable generator was brought to the site to power the pump system (and temporary auxiliary components), it failed its test run and was deemed unreliable. Weekend effort was expended to remove and replace the generator before Monday schedule start. Unit arrived late Saturday and passed its test. 6
Test Implem emen entation on & Com ompletion on: • Prestart Meeting conducted morning of scheduled Pump Test Monday, July 13,2020. With Well 6 pumping at an average rate of 436 gpm; varied from 430 and 448 gpm during the test. • Manual water level and flow measurements were recorded: First several hours of testing conducted by PGG. Remainder of pumping period conducted by CCA maintenance personnel. • Water was conveyed roughly 330’ from the wellhead to Blue Lake and was discharged onto an asphalt pad overlain with thick plastic sheeting to direct flow into Blue Lake and minimize its erosive potential. • The test concluded as planned on Thursday, July 16, 2020. • All equipment was removed from the site. Water level measurements from transducers downloaded by PGG and analyzed; water samples sent/ tested/ reported by certified labs From start to completion, the equipment performed without concern. No break in service, and TPD was Well 5 – 72 Hour 7 Test.
72 72-Hour T r Test Principal Q Questions Question 1: Is the groundwater under the influence of surface water No. Based on test results a risk factor of zero was calculated for Well 6 source water, which indicates that the well has a very low risk of being contaminated by surface water. Question2: Is the aquifer an unconfined or leaky confined aquifer? For DOH’s purposes the point is moot - the 72-hour test (required for an unconfined aquifer) demonstrated this well can sustainably produce water for a year straight of pumping. 7
72 72-Hour T Test Outcome Summa mmary • Pacific Groundwater Group issued a CCA Well 6 72-hour Aquifer Test Results and Analysis August 25 th , 2020 which answered the two questions asked by DOH: • PGG Recommendation: Lower well 6 pump intake at least 36’ (so it is 150’ below ground surface or deeper) When pump is installed, place well intake at least 130’ below ground surface. Under current conditions both wells should have adequate available drawdown to support the proposed water withdrawals. • Based on this sustainability analysis, if pump intakes are installed at appropriate depths Wells 5 and 6 should be able to pump continuously at 100 and 425 gpm for one year. 9
CCA A Path Forward to Capacity ty Build Out Well 5 & 6 NWWS draft response to DOH next week. • Report on 72-hour test results - 64% greater than goal (greater than full predicted build out) • Answers to design questions – currently at 90+% design for new 8" well/ treatment • Approaching Go/ No Go well approval on DOH Source 07 (8"and 6" wells) • No changes being discussed – assumption CCA is staying the course Wells 1 & 2 Well 2 repairs completed in 2020 – higher reliability • Floating suggestion to increase well 1 pump size to meet capacity • Unknown if the Aquifer has the capacity • Need to determine if existing well construction is limiting • Tests required to confirm if higher production rate possible • All eggs in one basket significant community risk increase • Believe NWWS has the right technical team to support CCA plans – CCA need to renegotiate the existing NWWS contract 9 Questions?...
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