| Low Pressure Sewer Construction |
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| What to Expect |
| 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 - Directional drilling: In selected cases, rather than using an open trench for pipes, work crews will use small drilling machines to install portions of the pipe network without significantly disturbing the area. This technique is used to protect heritage trees and deal with other restrictions like narrow rights-of-way and decorative driveways. Each drilling operation is usually finished within a few hours. Small piles of dirt and drilling medium at each end of the installed pipe could remain for a longer period. |
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Stage 4 - Mainline piping: Residents should expect inconveniences during construction of the 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 of various depths as other crews follow, assembling and installing lengths of pipe.
- The length of pipe installed in one work day varies from 300 to 1,500 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 5 - 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 6 - 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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| Stage 7 - Low Pressure Pump Station Installation: The county will install one grinder pump station near the home. The homeowner is responsible for the underground piping from the station to the connection at the street and the gravity service line from the home to the grinder pump station. The grinder pump stations are fiberglass tanks that are 2 to 2.5 feet in diameter, range in height from 5 to 8 feet, and are buried with the top flush with the ground surface. Each station will typically contain one pump and requires electrical power. |
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| How to Prepare |
- 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.
- During construction, keep children and pets away from work areas and equipment.
- Call the construction help line in your area with questions or problems. Representatives are standing by to resolve your concerns.
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 A property owner's guide to Low Pressure systems
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| Private plumbers working on an intstallation. | |
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| What is a Low Pressure / Ginder Sewer System? |
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Low pressure/grinder pump systems utilize a small grinder pump station at each wastewater source and small-diameter, low pressure sewer for transmission either to a lift station or directly to a wastewater treatment plant.
Raw wastewater from the residence or business is collected in a small grinder pump station.
Stations serving single residential units typically utilize fiberglass sumps 24 to 30 inches in diameter.
The grinder pump unit may be located in an easement, on private property or in the roadway right-of-way and requires a power source.
Commercial units are available in packaged, easily serviceable, low maintenance pump vaults which may be placed below grade and out of sight.
The grinder pumps typically range from 1 to 5 horsepower, depending on the type of pump selected and the number of units served by the pump station.
All solids in the waste stream are ground to a slurry and pumped through small diameter pressure sewers.
Since these systems do not rely on gravity, the sewers can be constructed with minimum cover (30 to 36 inches) and follow land topography.
Two common types of grinder pumps are in widespread use, submersible centrifugal grinder pumps and submersible progressive-cavity grinder pumps. | |
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