Santa Ana River Interceptor (SARI Line) Relocation Project

Project Location:

Yorba Linda and east Anaheim

Project Description:

The $50 million SARI Line Project relocated four miles of existing sanitary sewer out of the Santa Ana River floodplain in the City of Yorba Linda between Weir Canyon Road and the Orange/Riverside county boundary. Constructed in two phases (SARI Mainline and Yorba Linda Spur), over 20,600 feet of new 54-in diameter gravity sewer with a capacity of 43 million gallons per day was installed. Approximately 4,700 ft was installed by a 77-in to 101.5-in diameter microtunneling machine in five segments, including two inverted siphon river crossings and two curved drives, one of which is the longest compound curved, or “S” shaped, microtunnel in North America. Other work included installation of sewer and casing behind an existing tieback wall; construction of an odor control facility and a state of the art metering station; a bikeway detour; and a 5,000-foot major sewer lateral (also known as Yorba Linda Spur) that collects effluent from the City of Yorba Linda.

Project Justification:

The project is the largest, most expensive flood control project undertaken by the Orange County Flood Control District (OCFCD) and challenging in various aspects, as follows: 

1.  Flood Control: The project is an element of the $2.3 billion Santa Ana River Mainstem Project. Constructed in the mid-1970s, the Santa Ana Regional Interceptor in Yorba Linda, Calif., was originally constructed with approximately 20 feet of soil cover under the bed of the Santa Ana River. Over the years, the low-flow of the Santa Ana River meandered toward the existing SARI line and the river bed degraded significantly, leaving the SARI Line virtually exposed at several locations. These required costly periodic repairs by the facility owner, OCSD, including the placement of temporary rock riprap and grade stabilizers to protect the SARI Line. 

Continuing erosion and bed degradation put four miles of the old SARI Line in jeopardy of failure during heavy rainstorms. Recent upgrades to Prado Dam and other river improvements by the U.S. Army Corps of Engineers significantly increased the potential rate at which floodwaters can be discharged into the Santa Ana River. For these reasons, the relocation of the SARI Line outside the floodplain was required.

Sediment transport modeling was conducted to quantity the historical and future changes in the Santa Ana River morphology between Prado Dam and Weir Canyon Road. Recommendations from the study on burial depths and lateral scour were incorporated into the design. Moreover, in order to significantly reduce construction costs, most of the profile of the pipeline had to be raised above groundwater. To accomplish this, two inverted siphons up to 1,310 feet in length were constructed under the active river which raised the elevation of the pipeline to avoid significant dewatering and shoring.

2.  Sewage Disposal: The SARI line serves the sewage disposal needs of the cities of Yorba Linda, east Anaheim, Orange, and portions of Garden Grove, Santa Ana and Fountain Valley. It also serves parts of Riverside and San Bernardino counties and manages salt levels in groundwater throughout the region. Relocation of the SARI Line eliminates untold threats to public health, and catastrophic environmental and economic damages due to failure of the facility. In addition, the project prevents the release of over 60 million gallons of mostly raw sewage and brine into the river which could end up at the mouth of the Santa Ana River within a highly sensitive and publicly active coastal environment. Relocation of the pipeline would also eliminate the potential for entry of debris and sediment into the system which would damage OCSD’s pipeline and treatment plants located downstream.

3. Project Coordination: The project was constructed over a three-year period at a cost of $50 million. The project was managed by OCFCD in partnership with the Orange County Sanitation District (OCSD), the Santa Ana Watershed Project Authority (SAWPA), and the U.S. Army Corps of Engineers, Los Angeles District (Corps).

The planning, design, and construction required significant coordination with almost two dozen stakeholders, eight property owners, and two major businesses (Green River Golf Club and Canyon Recreational Vehicle Park) over a ten year-period. The joint EIR/EIS was prepared by the Corps and satisfied both State and Federal requirements.

The construction included work within the Santa Ana River floodplain where sensitive habitat and threatened and endangered species are present. Coordination with the US Fish and Wildlife Services was frequent during the nesting seasons which avoided harmful disturbances to the endangered Least Bell’s Vireos which were observed nesting and foraging during construction.

In order to avoid conflicts with two other contractors who were concurrently working within the area, the SARI Line construction also required extensive coordination with these Corps-sponsored projects in regard to scheduling and project phasing.

4. Microtunneling: Microtunneling was required due to the depth of pipe installation and to avoid construction impacts to the community and the environment along the river. The project included five microtunnel drives through extremely abrasive soil conditions in environmentally sensitive areas using state-of-the-art Herrenknecht microtunnel boring machines (MTBMs). The specified minimum microtunneling equipment requirements with face access and compressed air lock was, in part, due to the potential for encountering groundwater and anticipated abrasiveness of the ground and the possibility of large boulders. However, all five drives were completed without the need for interventions.

Microtunneling records were set:  the longest curve (2,187 ft.) and longest compound, or “S”, curve (1,567 ft.) in North America.

5.  Geologic conditions: Soil conditions on the project include a complex mix of alluvium with abundant cobbles and boulders in a weak sandy matrix. During design, subsurface investigation reports indicated abrasive soils based on Miller testing. Groundwater levels with high hydraulic conductivity were well above the pipeline elevation during flood season along several of the tunnels which was challenging. In fact, aquifer tests showed that the groundwater table can recover as much as 88% of its initial static level within one minute after pumping was stopped. To counteract, temporary shaft structures were excavated up to 70 feet deep and included the use of cement deep-soil mixing, secant piles and soldier pile and lagging walls with permeation grouting designed to limit groundwater inflow.

6. Narrow Right-of-Way, Sensitive Habitat and Water Quality: Located within a narrow strip of right-of-way between the 91 freeway and the river low flow, several unique construction methods were utilized including the use of sheet pile retaining walls and work behind an existing tieback wall. Maintaining the integrity of the pipeline also safeguards water quality in the river and the sensitive habitat that is home to dozens of fish, birds and wildlife species that live in and along the Santa Ana River. The coastal waters and beaches in Huntington Beach and Newport Beach and the Orange County Water District recharge basins in Anaheim are also protected from the adverse effects of a breach in the pipeline. Ensuring the integrity of the pipeline safeguards Inland Empire businesses against a break in service, and protects the Orange County Sanitation District treatment facilities.

7. Right-of-way Acquisition: Approximately 13.9 acres of Caltrans right-of-way along the westbound Riverside Freeway (SR-91) within Orange County was relinquished to OCFCD in order to relocate the SARI outside of the Santa Ana River floodplain. A Project Study Report/Project Report (PSR/PR) was completed in 2010 which concluded that the relinquishment would be compatible with the future widening of the SR-91, including the proposed extension of an additional 91 Express Lane to Riverside County to accommodate the proposed SR-241/SR-91 direct connector and the proposed widening of the SR-91 between Weir Canyon Road and SR-241 pursuant to the Riverside County-Orange County Major Investment Study.

A tri-party agreement was needed among OCFCD, County (OC Parks), and Canyon RV Park for the purchase of right-of-way to construct the pipeline and metering station within Featherly Regional Park and to compensate its lessee (Canyon RV Park) for business impacts and lost revenue. Construction within the Canyon RV Park was carefully planned and implemented successfully which minimized the duration of construction within the park and, consequently, the impacts to the business and park operations.

OCFCD also coordinated with The Irvine Company to lease a portion of its idle property near the jobsite for a 5-acre construction staging and laydown area for pipes and equipment.

8. Construction Permits and Mitigation: The SARI Line Project required the acquisition of, among others, the major regulatory permits including Section 404, 1600 and 401 permits and encroachment permits from Caltrans. OCFCD has coordinated with the implementing agencies and successfully negotiated for reasonable mitigation measures and requirements that are acceptable to OCFCD. The SARI Line Project also acquired a Section 408 permit from the Corps due to proposed modifications to the Corps-constructed Santa Ana River levee. OCFCD was also able to obtain a right-of-entry permit from the California State Parks to construct a bikeway detour within its property. This bikeway detour was later on used in other projects wherein OCFCD was a local sponsor.

9. Agreement with Various Agencies: OCFCD has entered into a financing agreement with OCSD and SAWPA in which OCSD loaned 60% and SAWPA loaned 10% of the project cost to OCFCD. Reimbursements from the State Flood Subvention funds will be used to repay the loans. OCFCD has also entered into an agreement with the City of Yorba Linda with regards to ownership and maintenance of the Yorba Linda Spur. OCFCD has also entered into an agreement with the Canyon RV Park lessee and the County of Orange (OC Parks) to acquire temporary and permanent easements within the park and to compensate the lessee for impacts to business and operations.

10. Public Trail Issue: The Santa Ana River Trail (SART) is a multi-use trail that runs alongside the Santa Ana River in southern California. The SART is the most heavily used trail in Orange County and traverses the project limits along La Palma Avenue to the north, along Gypsum Canyon Road which crosses the Santa Ana River, and along Riverside Freeway to the south. Trail detours were constructed to prevent closures and several coordination meetings were held with the cycling community to minimize interruptions to bicyclists and other trail users. Reconstruction of trail improvements was one of the components of the SARI Line project.

Special Circumstances:

The SARI Line was managed and funded by Orange County Flood Control District with loans from OCSD and SAWPA, the EIR/EIS was prepared by the US Army Corps of Engineers, and Caltrans provided land to the Orange County Flood Control District along the SR-91 freeway for this project.

The project design was led by Tetra Tech, Inc. with the following major subconsultants:

• HDR, Inc.
• Hatch Mott McDonald
• Leighton Consulting, Inc.

MWH Constructors provided construction management services on the project.

Project Attachments:


Award Citation::

The completion of the $50 million Santa Ana River Interceptor (SARI Line) Relocation Project marked a major milestone of the Santa Ana River Mainstem Project. The relocation allows Prado Dam to operate at its new increased design capacity and ensures continued and uninterrupted sewer services for residents and businesses of Orange County and the Inland Empire.

Suggested Award Summary:

The 2014 ASCE Orange County Project of the Year is awarded to the Orange County Flood Control District for the successful completion of the Santa Ana River Interceptor (SARI Line) Relocation Project. The $50 million project began construction in 2011 and its completion marked a major milestone of the Santa Ana River Mainstem Project which allows Prado Dam to operate at its new increased design capacity. This project successfully relocated the SARI Line out of the Santa Ana River floodplain which was in danger of damage due to river bed erosion and degradation. This ensures continued and uninterrupted sewer services for residents and businesses of Orange County and the Inland Empire. This project involved multiple organizations including the Orange County Flood Control District, the Orange County Sanitation District, the Santa Ana Watershed Project Authority, the County of Orange (OC Parks), Caltrans, California State Parks, the City of Yorba Linda/Yorba Linda Water District, the City of Anaheim, The Irvine Company, and the US Army Corps of Engineers, Los Angeles District.

The SARI Line project was constructed to relocate the SARI Line out of the floodplain along a four-mile section of the Santa Ana River that had experienced scour and bed degradation which, in some locations, virtually exposed the pipeline. The exposed pipeline was at risk of damage and rupture during a major storm event. With the successful relocation of the pipeline, the threat of damage to the pipeline has been significantly reduced and the Prado Dam and the downstream channel will be able to operate at full capacity, including the release of 30,000 cubic feet per second (13.5 million gallons per minute) of flood waters.


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