FROM: Robert Thompson, General Manager
Originator: Mike Dorman, Director of Engineering
SUBJECT:
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SUNFLOWER PUMP REPLACEMENT AT PLANT NO. 1, PROJECT NO. FE19-04
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GENERAL MANAGER'S RECOMMENDATION
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RECOMMENDATION:
Approve a contingency increase of $318,480 (15%) to the construction contract with GSE Construction Company Inc. for Sunflower Pump Replacement at Plant No. 1, Project No. FE19-04, for a total construction contingency of $530,800 (25%).
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BACKGROUND
The Orange County Sanitation District (OC San) Sunflower Pump Station transfers flows into Headworks from the deepest of the trunk sewers feeding Plant No. 1. The pump station uses two 40-million gallon per day screw pumps to lift flow from the Sunflower Trunk into Plant No. 1. The screws for those pumps are approximately 32 feet long, have a 9-foot diameter, and are driven through a large gearbox to reduce the speed of the 150-horsepower motor down to 28 revolutions per minute. These pumps are subject to erosion of the screws, corrosion from the sewer gas, and wear and tear on bearings submerged in wastewater.
RELEVANT STANDARDS
* Protect OC San assets
* Maintain a proactive asset management program
* 24/7/365 treatment plant reliability
PROBLEM
The original contract included the replacement of the Pump 1 screw pump and the replacement of the grout and polyurethane coating in the trough area underneath the pump. During the removal of the screw pump, the contractor discovered extensive damage to the concrete and coating in the area above the trough, which is not part of the project scope. In addition, during construction it was discovered that an existing control and signal duct bank for the screw pumps is not correctly shown on existing as-built drawings and interferes with a future stairway constructed for the existing Metering and Diversion Structure by Project No. P1-105, Headworks Rehabilitation at Plant No. 1, and needs to be rerouted. Replacing these...
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