Sun Terrace Pump Station Improvements and Hillsborough Drive Pipeline Abandonment Project

Sun Terrace Pump Station Improvements and Hillsborough Drive Pipeline Abandonment Project

The purpose of the Project is to replace aging equipment and pipeline at the Sun Terrace Pump Station and abandon aging pipeline within the City of Concord right-of-way. Within the pump station site, the Project will replace aging equipment, valves, and approximately 110-ft of 6-inch cast-iron pipeline, as well as complete interior relining and exterior recoating of the two (2) 5,000-gallon hydropneumatic tanks. Within the City of Concord right-of-way, the Project will abandon approximately 300-ft of 6-inch and 8-inch asbestos cement (AC) pipeline and install approximately 160-ft of new 6-inch and 12-inch pipeline. The Project will also replace existing residential services, moving their supply connection from the asbestos cement pipeline to the newer parallel polyvinyl chloride (PVC) pipeline. The Project is entirely within the existing CCWD treated water service boundary, and since the parcels now receive CCWD water, the Project will not result in an expansion of service. The Project construction is expected to take up to 3 months, starting in March 2026, and is expected to be completed by May 2026. The pump station's 6-inch cast-iron pipeline will be replaced with ductile iron (DI) pipeline of the same size. The public right-of-way pipeline installation consists of installing new 6-inch and 12-inch PVC and DI pipes. The new 6-inch pipe will match the existing pipe size on Greenbrier Street, and the short length of new 12-inch pipe on Hillsborough Drive connects existing pipeline to facilitate abandonment of the existing AC pipeline. These pipes will be transported in 20-foot sections to the area. The north side of the pump station is vacant and has been identified as a potential staging area for the contractor to store materials, minimizing disruption to both pedestrians and vehicles in the public right-of-way. The existing pipelines and old service lines that will be replaced by this Project will be abandoned in place per CCWD Standards. Therefore, no disruption will occur from pipe removal. A backhoe will be used to dig a trench approximately two feet wide by four feet deep on these streets within the pipeline replacement construction area forthls Project. The trench will be covered each night using metal trench plates; wood, metal and/or hydraulic shoring and bracing will be used as necessary to shore up the sides of the trench in all locations. This trench covering and shoring materials will be stored onsite in an area that minimizes disruption to the surrounding residents. Once the pipeline is Installed, the trench will be compacted and backfilled with imported aggregate base and/or excavated soils, and the site will be restored. It is possible during construction that existing service lines in the area could be disrupted, however this will be temporary and not exceed longer than eight hours at any given time during the construction. CCWD will provide advance notice to homeowners in the vicinity before the start of construction activities. Homeowners will also be given notice 24-hours in advance of any service disruption. Finally, the asphaltic concrete (AC) pavement surface will be repaired and reconstructed to match existing conditions and conform to City standards. It is expected that up to twenty (20) round-trip truck trips (40 one-way) will be needed to transport the pipes and other material over the life of the 3-month project. No more than twenty round-trip truck trips (40 one-way) will occur on any given day and will be typically spread out over a 9-hour work period, from 8 am to 5 pm. The Project will require obtaining an encroachment permit from the City of Concord. The permit will be completed before construction starts and will contain all City requirements for the work. There will be no full street closures or detours because of this project; a minimum of one lane of traffic wilt be maintained at all times. Flag persons will be on-site as necessary. During the pipeline installation process1 it will be necessary to flush the new lines, and up to 2,000 gallons of treated water may be discharged cumulatively during the life of the 3-month Project. During the tank coating testing process, up to 20,000 gallons of treated water may be utilized and discharged. Both the pipeline flushing and tank coating testing water will be dechlorinated pursuant to CCWD's Best Management Practices (BMPs), and then will be discharged into the City's storm drain system. This discharge will be covered under the Order WQ 2014-0194~DWQ GENERAL ORDER NO. CAG140001 Statewide National Pollutant Discharge Elimination system (NPDES) permit for drinking water system discharges to water of the united States. Pipeline and equipment installation within the pump station site will necessitate removal of one Eucalyptus tree. The tree is located in the front yard of the pump station site and is not within the public right~of-way. Per City of Concord tree removal permit requirements, Eucalyptus trees are identified as non-protected trees and do not require a permit for removal. The following equipment will be used during construction: saw cutting machine, backhoe, backhoe trailer, excavator, dump truck, boom truck, and crew vehicles. As stated above, all construction materials and equipment will utilize lay down areas located within the public right-of-way but will be stationed in one place for a maximum of one week at a time. The Project site is within a suburban residential housing area and thus the Project will not adversely affect natural resources such as open space areas, wetlands, and riparian corridors or areas of known cultural and historic resources. Much of the Project area is already disturbed, and the Project will take place in roadways within the public right-of-way and within the pump station site. As a result, impacts on natural and/or cultural resources are not anticipated.

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