Thunderbird Drive and Vicinity Pipeline Replacement Project

Thunderbird Drive and Vicinity Pipeline Replacement Project

The Project will replace approximately 2 miles of existing water main infrastructure on eight suburban streets in Concord, CA. The purpose of the Project is to upgrade the neighborhood's aging water system, which has a history of leaks, with a new, more reliable system. In addition to the water main, this Project will also upgrade lateral service lines, valves, and all other equipment necessary to provide potable water service to these customers. The Project is entirely within the existing CCWD treated water service boundary, and since the parcels currently receive CCWD water, the Project will not result in an expansion of service. This water pipeline replacement is expected to take up to 10 months, starting in September 2025, and is expected to be completed by July 2026. This Project consists of the installation of new 6-inch and 8-inch polyvinyl chloride (PVC) and ductile iron (DI) pipes. The new pipe sizes will match existing on Thunderbird Drive, Thunderbird Court, Skylark Drive, Cardinal Drive, Falcon Drive and Michele Drive and increase minimally on Cardinal Court to support fire flow demands. These pipes will be transported in 20-foot sections to the area. Since the area is developed with single-family homes, the pipes will be stored in small piles throughout the work area to reduce disruption of both pedestrian and vehicular circulation. The Project will be under construction for a few days in front of each residence and therefore, these 20-foot sections of pipes will typically be stationed in one place for a maximum of one week at a time. 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 for this 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 County standards. It is expected that up to one hundred twenty (120) round-trip truck trips (240 one-way) will be needed to transport the pipes and other material over the life of the 10-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 10-hour work period, from 7 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 of Concord requirements for the work. There will be no full street closures or detours because of this project; a minimum of one lane of traffic will be maintained at all times. Flag persons will be on-site as necessary. During the pipeline installation process, it will be necessary to flush the new lines, and up to 160,000 gallons of treated water may be discharged cumulatively during the life of the 10-month Project. This water will be dechlorinated pursuant to CCWD's Best Management Practices (BMPs), and then will be discharged into the County'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. 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 would take place in roadways within the public right-of-way. As a result, impacts on natural and/or cultural resources are not anticipated. A public school, Sun Terrace Elementary School, is located within the project area. CCWD will coordinate with the school to minimize impacts on school drop-off and pick-up activities.

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