Agenda Packets - 2016/09/12 - Laserfiche WebLink

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Item No: 7H Meeting Date: September 12, 2016 Type of Business: Council Business Administrator Review: ____ City of Mounds View Staff Report To: Honorable Mayor and City Council From: Don Peterson, Public Works Supervisor Item Title/Subject: Resolution 8628 Authorizing Blue Earth Labs and Hawkins Water Treatment Group to Perform Repairs on Water Treatment Plant #2 Filter Media Cleaning Background/Discussion: The Public Works Department has many responsibilities including efficiently operating the water distribution system. The system includes (6) wells, an elevated water tower, a ground reservoir, a booster station and (3) water treatment plants. The water treatment systems have been in operation for over 25 years with no major upgrades or repairs to the system. Routine maintenance has been performed on the well motors and pumps while the operating systems and controls have had only minor repairs. Public Works Staff noticed a decrease in water production from Well #5 / Water Treatment Plant #2. Staff started to investigate the cause for the loss of production, believing it was a valve issue, possibly a control issue, or the well motor and pump. Many of the components were checked and found to be in working order. Staff contacted Advanced Engineering and Environmental Services, Inc. (AE2S), since they would be performing the water production control assessment, to request their assistance with the issue of the lost water production. AE2S meet with Staff and after discussing the problems recommended that Blue Earth Labs in partnership with Hawkins Water Treatment Group be contacted to evaluate the condition of the filter media. Since the plant was placed in operation in 1969, the filter media is original, no additional media has been added and no maintenance to the media has taken place since. A core sample of the media has taken and tested by Blue Earth Labs. The following is an overview of the findings from Blue Earth Labs: The Sand media sample is covered with mixed deposits consisting of different minerals with the primary metal contaminant being calcium. A layer of top sludge from filter 3 was also provided as representative of the sludge from filter 4. Microscopy, the mineral content in the reaction supernatants, and dry weight loss show that there is significant fouling on the tested media. For this particular sample, a standard 4x treatment resulted in removal of an estimated 62% of the deposits and minerals. Based on the laboratory testing, treating the media will remove approximately 1790 lbs of deposits from Filter 4.