What is the Mission Trunk?
The Mission Trunk is a critical sewer line that collects wastewater from smaller collection pipes in SASD’s northeast service area, which includes Citrus Heights, Carmichael, Fair Oaks, and Orangevale. The trunk was constructed in 1962-1963 and consists of 6.5 miles of reinforced concrete pipe ranging in size from 36 to 75 inches in diameter.
Where is the Mission Trunk?
Generally following the Mission Avenue corridor (see map), the Mission Trunk begins upstream near American River College and ends downstream near the American River, where it connects to other sewer pipes that lead to the Sacramento Regional Wastewater Treatment Plant located near Elk Grove.
Why is the Mission Trunk Sewer Rehabilitation Project necessary?
SASD conducts proactive system maintenance and inspections to ensure our sewer lines are in top shape. We also conduct rigorous condition assessments to identify and address system needs. Recent inspections of the Mission Trunk have indicated there is moderate to severe corrosion in several sections of the sewer line. Therefore, the trunk is undergoing rehabilitation, which is a repair and renewal process to return this stretch of sewer pipe to optimal operating performance.
What does the Mission Trunk Sewer Rehabilitation Project involve?
The Mission Trunk Sewer Rehabilitation Project includes the following activities:
- Rehabilitating nearly 3 miles of deteriorated pipe using a trenchless pipe lining method called cured-in-place-pipe (CIPP)
- Installing temporary bypass pipes and pumps to keep Mission Trunk wastewater flowing during the work
- Relocating manholes from backyard easements to street locations
- Rehabilitating or replacing SASD and Regional San structures and facilities
- Constructing new manholes
When will the work occur?
Beginning in April 2020, work will be performed in various phases on three major segments of the Mission Trunk (see map). Most of the work will take place Monday through Friday from 7:00 a.m. to 6:00 p.m. Work is scheduled to continue in phases until February 2021. Night or weekend work may be necessary at times to complete critical tasks or minimize impacts. Bypass piping and pumps will remain in place during the work on each section of the trunk.
How will this construction project impact me?
As always, SASD and its contractors will do everything possible to minimize construction impacts. During the work, drivers may experience occasional lane closures or traffic slowdowns in work zones. Construction of some structures may require temporary road closures, and since bypass pumps and piping will remain in place during the work on each section, some lane shifting and turn restrictions may also be required. Typical construction noise, dust, and odor are other possible impacts. However, sewer service will not be interrupted.
What types of construction activities can I expect during the project?
You may see bypass pumps and pipes, trucks and equipment, and large CIPP preparation tents erected within the work area. Special truck-mounted equipment will be used during the CIPP insertion and curing process. There will be minimal digging around some of the manholes and shallow burial of some of the bypass pipes along the side or center of the road.
What is Cured-In-Place-Pipe?
Cured-in-place-pipe (CIPP) is one of the most widely used and cost-effective rehabilitation methods to repair existing sewer pipes. It is a jointless, seamless, corrosion-resistant pipe lining that is inserted within an existing pipe—basically a “pipe within a pipe.”
How is CIPP installed?
CIPP is installed through existing manholes. After bypassing all sewer flow, the upstream section of the manhole is temporarily removed, and the CIPP liner is inserted into the sewer pipe from the manhole using water pressure. The CIPP liner is then cured to a hardened state using hot water. To learn more about this method, watch a CIPP demonstration video.
What are the advantages of the CIPP rehabilitation process?
In comparison to traditional open-cut construction, this trenchless rehabilitation of sewer pipe is less disruptive, can be completed on a shorter schedule, and generally costs much less. Using CIPP means less impact to traffic and fewer inconveniences to surrounding neighborhoods.
What are the impacts of CIPP?
During the Mission Trunk Sewer Project, SASD and its contractors will make every effort to minimize construction impacts, including the following:
- Preparation tent: To prepare the CIPP lining materials, the project team sets up a tent that measures approximately 150 feet long and 25 feet wide (see photo) over the manhole. Crews then insert the liner into the sewer pipe through the manhole.
- Continuous operation: Once the CIPP lining process begins, crews must work 24/7 until the CIPP liner is completely inserted and has cured. The duration of the lining process varies based on the length and diameter of the CIPP liner. The shorter the section of sewer being lined, the less time it will take. At most locations, two sections are completed and generally each section will take one week to complete.
- Noise: During CIPP work, homes and businesses near the work area can expect noise impacts from various types of equipment, such as generators, boilers, and heavy equipment. This equipment is necessary to remove the top of the manhole and then insert and cure the CIPP liner.
- Odor: When the top of the manhole is temporarily removed, homes and businesses near the work area may notice odor from the open manhole until the CIPP liner is inserted into the sewer pipe. Additionally, odors similar to plastic or glue may be present during the insertion of the resin into the liner and when hot water is used to cure (harden) the CIPP liner. This odor is from the material within the CIPP liner. While this odor may be noticeable, please be assured that the Sacramento Metropolitan Air Quality Management District has determined that the air emissions associated with this project meet all local, state, and federal requirements for the protection of public health.
- Traffic and property access: In some instances, the location of the preparation tent may require lane closures and temporarily block driveway access to homes and businesses. In these situations, SASD and its contractors will coordinate closely with affected property owners both before and during the work.
Are the odors from CIPP harmful?
No. While the odor can be unpleasant for some, the Sacramento Metropolitan Air Quality Management District has determined that the air emissions associated with this project meet all local, state, and federal requirements for the protection of public health.
How long will the odor be present?
Odor can be expected while the CIPP work is going on in your area, which is usually for a couple weeks at each insertion location. Once the liner is in place and fully cured, the odor will dissipate. This could take up to two or three days after the crews have finished and moved on to the next section of pipe.
What should I do if the odors bother me?
We recommend closing your doors and windows if the smell is unpleasant. Because the CIPP lining process is a 24/7 operation, odor may be noticeable even after normal working hours. We appreciate your patience during this temporary inconvenience. If you have questions or concerns, please call the Mission Trunk Sewer Project hotline at 916-876-SASD (7273).
More CIPP Resources
What is bypass pumping?
Bypass pumping is a temporary system to convey wastewater around a section of sewer that is being worked on. This allows the repair or replacement of a section of sewer without affecting the flow of wastewater while work is underway. Bypass pumping is critical when existing sewer lines are rehabilitated because the flow of wastewater typically cannot be diverted or stopped. During the Mission Trunk project, we are committed to maintaining uninterrupted sewer service to our customers; therefore, bypass pumping will be in place during rehabilitation for several months. Because the bypass pumping system must operate around the clock, the construction contractor will monitor it at all times.
Where will the bypass pipes be located?
Bypass pipes will run along road shoulders or down the center of the street (protected by K-rail barriers). At most intersections, the bypass pipes will be buried in shallow trenches to allow unrestricted vehicle movement and turns. View the project maps for bypass locations:
How can I find out more about construction activities?
Construction information and updates will be posted here, so please check back periodically. In addition, if you have a question or concern, please call our project hotline at 916-876-SASD (7273). If you have an urgent issue that needs immediate attention, please call 916-875-6730. The community along affected areas of the Mission Corridor will also be kept informed through direct mailings, NextDoor social media announcements, and updates in Supervisor Peters’ community meetings and monthly emails.