| Gravity Sewer Construction |
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| What to Expect During Construction |
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This is a summary of the construction process. The contractor will give as much notice as possible before beginning work on your street. |
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| Stage 1 - Survey Staking and Pre-construction Video - This stage includes physical staking of the proposed utility system using wooden stakes or other markers. After staking, the site will be video taped to record pre-construction conditions. Residents are urged to not disturb the survey stakes/markers. |
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| Stage 2 - Right-of-way trimming and clearing - This stage could take a few days per street and may involve cutting and removing driveway sections, drainage structures and other obstructions located in public rights-of-way or dedicated utility easements. |
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Stage 3 - Gravity Sewer Mains - Residents should expect inconveniences during construction of the gravity sewer collection lines.
- Work crews will cross driveways, walkways and may excavate entire streets.
- Streets will remain open, but partial lane closures may be necessary.
- Residents will notice the contractor digging trenches varying in depths from 4 to 18 feet deep while assembling and installing lengths of pipe.
- The length of pipe installed in one work day varies from 100 to 500 feet depending on ground conditions.
- A resident's driveway may be inaccessible for a short time.
- By the end of each day, the contractor will temporarily restore driveways and replace mailboxes and backfill trenches and/or otherwise erect approved safety barricades and fencing.
- Because of high water table conditions, groundwater "dewatering" is often necessary.
- This involves setting temporary well points and pumping groundwater with portable pumps and hoses to approved points of discharge, usually into existing stormwater drainage systems.
- Sometimes the dewatering equipment operates during the evening and it is important that only authorized personnel operate and adjust this equipment.
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| Stage 4 - Lateral Service Lines - The contractor will install lateral gravity service pipes extending from the gravity sewer main in the right-of-way to the private property line. Once the system is certified for use, residents will be notified that they may hire private contractors to install gravity service lines from their homes to the service laterals located at the right-of-way line. |
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Stage 5 - Directional drilling - Gravity sewer mains flow to a lift station, which in turn, pressurizes and pumps the wastewater via a force main pipe to the water reclamation facility.
- In selected areas, rather than using an open trench for force main pipes, work crews will use directional drilling machines to install portions of the pipe without significantly disturbing the area.
- This technique is used in narrow rights-of-ways or major thoroughfares to minimize traffic disruption and also to protect various structures or natural features, such as heritage trees.
- Drilling operation may last a day or more and piles of dirt and drilling medium at each end of the installed pipe could remain for a longer period.
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| Stage 6 - Restoration - The contractor will rely on the construction plans and the pre-construction videotape when restoring construction areas to original conditions. Restoration activities that will begin once the pipe installation is complete may take several weeks, or even months. Residents with concerns about the quality of restoration work should call the construction help line for their area. The county will resurface roads in the project area after all restoration is complete. |
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Stage 7 - Notice of service availability - The county will notify residents when it is time to abandon septic systems and connect to the sewer system. You will receive a complete package of information on how to connect. |
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How to Prepare |
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Plan now to remove unpermitted obstructions (sprinkler systems, shrubbery, etc.) from the public right-of-way or dedicated utility easement. The county cannot guarantee they will be replaced.
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During construction, keep children and pets away from work areas and equipment.
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Call the construction help line in your area with questions or problems. Representatives are standing by to resolve your concerns. | |
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| What is a Gravity Sewer System? |
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Conventional gravity sewers convey raw, untreated sewage through pipelines to a treatment facility or lift station.
The sewer lines are straight and installed on a specific horizontal and vertical alignment, with interspaced manholes placed at set intervals, at pipe intersections and at changes in pipeline direction.
The pipes are installed with uniform gradients sufficient to create a self-cleansing velocity of two feet per second.
Concrete manholes allow access for inspection, cleaning, and repair.
Construction of these systems on flat terrain typically requires deep excavations (6 to 12 feet below grade) and proper preparation and bedding materials are required in the pipeline trenches.
Sarasota County standards restrict the depth of burial to 18 feet, at which point a lift station is built to pump wastewater to another location, such as another pump station or a wastewater treatment plant through a force main.
The sewers and manholes are most typically installed along the centerline of roadways and have service collection laterals extending perpendicular to the roadway alignment.
If required, a lift/pump station collects the sewage transported by the collection piping.
The station consists of a wet well with either submersible or non-submersible pumps.
Typically, two alternating, non-clog wastewater pumps remove waste from the collection tank and discharge it through a force main.
Level probes in the wetwell control the operation of the pumps.
Non-submersible components of the lift station are located above the 100-year flood elevation. | |
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