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HomeMy WebLinkAboutAgenda Report - November 1, 2017 C-07CITY OF LODI COUNCIL COMMUNICATION TM AGENDA TITLE: MEETING DATE: PREPARED BY: AGENDA ITEM C -7 Accept Improvements Under Contract for White Slough Water Pollution Control Facility 2016 Improvements Corrosion Repair Project November 1, 2017 Public Works Director RECOMMENDED ACTION: BACKGROUND INFORMATION: Accept improvements under contract for White Slough Water Pollution Control Facility 2016 Improvements Corrosion Repair Project. The original project consisted of repairs to and coating of concrete structures and process channels, surface preparation and coating of existing piping, replacement of corroded access hatches, and demolition of abandoned piping. The contract was awarded to Western Water Constructors, Inc., of Santa Rosa, in the amount of $1,039,650, on June 15, 2016. The contract has been completed in substantial conformance with the plans and specifications approved by City Council. The final contract amount was $1,584,078, a difference of $544,428. The difference in the final contract amount and the original contract amount was due to a combination of six change orders that were required to address either unknown conditions or additional work requested by the City, and a decrease in estimated unit quantities that resulted in a credit of $197,512. Change Order No. 1 consisted of the removal of grit in the primary influent channels. The primary influent channels are the initial step in the treatment process. Grit (larger, heavy particles) is intended to settle in this area but it is difficult to estimate quantities since the grit is submerged while the treatment plant is in operation. Since the concrete surfaces in this area were being repaired, all of the grit needed to be removed. The estimated amount of grit removal was less than the actual amount removed ($42,762). Change Order No. 2 consisted of cleaning the anaerobic Digester No. 3 in preparation for removing and replacing the existing internal coating system; additional concrete repairs at the headworks and primary influent deck areas and miscellaneous electrical work ($100,914). Change Order No. 3 consisted of miscellaneous electrical and instrumentation work requested by the City. This work was performed by change order in response to a notice of violation received from the State Water Resources Control Board. The violation notice required the City to install pond level sensors to minimize pond overtopping exposure ($83,809). Change Order No. 4 consisted of removing and replacing the coating system on the interior surfaces (including the dome roof) of Digester No. 3. This City requested work was performed upon staff discovering corroded elements within Digester No. 3 that indicated the need for proactive repairs in order to avoid the scenario associated with Digesters No. 1 and No. 2 where emergency repairs were needed to address corrosion related roof failures in 2014 ($115,157). APPROVED: to K:\WP\PROJECTS\SEWER\WSWPCF\WSWPCF 2016 corrosion repairs\CAccept.doc batter, City Manager 10/24/2017 Accept Improvements Under Contract for White Slough Water Pollution Control Facility 2016 Improvements Corrosion Repair Project November 1, 2017 Page 2 Change Order No. 5 consisted primarily of various bypass pumping -related changes during the process channel repair work, and the replacement of corroded components and additional valving in order for the bypass pumping to be successfully performed. This change order also included the repair of corroded elements of the Digester No. 3 roof cover; and replacement of the original (1968) 24 -inch diameter steel air main pipe that conveys forced air to the aeration basins after staff noticed air being pushed through the pavement over the pipe location. To minimize the risk of substantially impacting plant operations and water quality, the repairs were postponed until the summer months when an interruption in aeration would be less critical to the treatment process. This decision is the primary cause for the contract extensions ($107,532). Change Order No. 6 consisted of additional extra work associated with the 24 -inch diameter steel air main pipe. During replacement it was found that a portion of the pipeline located beneath the blower room floor had corroded and also needed replaced; and that the pipeline had been encased in concrete requiring additional work to facilitate the old pipe removal. This change order also included replacement of electrical conduits embedded within the concrete encasement; and trench paving ($93,823). The contract was completed on September 25, 2017. Photos of the work are shown in Exhibit A. Following acceptance by the City Council, as required by law, the City Engineer will file a Notice of Completion with the County Recorder's office. The notice serves to notify vendors and subcontractors that the project is complete and begins their 30 -day period to file a stop notice requiring the City to withhold payments from the prime contractor in the event of a payment dispute. FISCAL IMPACT: This project was needed to avoid more costly repairs or complete replacement of facility concrete structures in the future. Approximately $506,000 of the increase in contract price was associated with repairing the interior of Digester No. 3 and replacing the original steel air main pipe; both elements of the facility which were discovered to be either failed, or failure was impending. Utilizing this contract to perform these repairs saved valuable time and reduced the City's risk of regulatory fines associated with water quality/process violations. FUNDING AVAILABLE: This project was funded by Fiscal Year 2016/17 Wastewater Capital Fund (53199000.77020). Charles E. Swimley, . Public Works Director CES/CES/tdb Attachment cc: Western Water Constructors, Inc. Wastewater Plant Superintendent West Yost Associates K:\WP\PROJECTS\SEWER\WSWPCF\WSWPCF 2016 corrosion repairs\CAccept.doc 10/24/2017 EXHIBIT A 'MO! .....'.:.r. ...... . .......'n. .. . eV.... FFilr-141111K .1, •. . .. • .• a. S.. • . • - 411 54 . • • • ... - St 0 • ' • 4m .44 • • • • •• •• '..1, • n; • 1:k. : '• IN.